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Sample records for flexible pacemaker function

  1. Synergism of coupled subsarcolemmal Ca2+ clocks and sarcolemmal voltage clocks confers robust and flexible pacemaker function in a novel pacemaker cell model.

    Science.gov (United States)

    Maltsev, Victor A; Lakatta, Edward G

    2009-03-01

    Recent experimental studies have demonstrated that sinoatrial node cells (SANC) generate spontaneous, rhythmic, local subsarcolemmal Ca(2+) releases (Ca(2+) clock), which occur during late diastolic depolarization (DD) and interact with the classic sarcolemmal voltage oscillator (membrane clock) by activating Na(+)-Ca(2+) exchanger current (I(NCX)). This and other interactions between clocks, however, are not captured by existing essentially membrane-delimited cardiac pacemaker cell numerical models. Using wide-scale parametric analysis of classic formulations of membrane clock and Ca(2+) cycling, we have constructed and initially explored a prototype rabbit SANC model featuring both clocks. Our coupled oscillator system exhibits greater robustness and flexibility than membrane clock operating alone. Rhythmic spontaneous Ca(2+) releases of sarcoplasmic reticulum (SR)-based Ca(2+) clock ignite rhythmic action potentials via late DD I(NCX) over much broader ranges of membrane clock parameters [e.g., L-type Ca(2+) current (I(CaL)) and/or hyperpolarization-activated ("funny") current (I(f)) conductances]. The system Ca(2+) clock includes SR and sarcolemmal Ca(2+) fluxes, which optimize cell Ca(2+) balance to increase amplitudes of both SR Ca(2+) release and late DD I(NCX) as SR Ca(2+) pumping rate increases, resulting in a broad pacemaker rate modulation (1.8-4.6 Hz). In contrast, the rate modulation range via membrane clock parameters is substantially smaller when Ca(2+) clock is unchanged or lacking. When Ca(2+) clock is disabled, the system parametric space for fail-safe SANC operation considerably shrinks: without rhythmic late DD I(NCX) ignition signals membrane clock substantially slows, becomes dysrhythmic, or halts. In conclusion, the Ca(2+) clock is a new critical dimension in SANC function. A synergism of the coupled function of Ca(2+) and membrane clocks confers fail-safe SANC operation at greatly varying rates.

  2. 21 CFR 870.3640 - Indirect pacemaker generator function analyzer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indirect pacemaker generator function analyzer... Indirect pacemaker generator function analyzer. (a) Identification. An indirect pacemaker generator function analyzer is an electrically powered device that is used to determine pacemaker function or...

  3. Pacemaker

    Science.gov (United States)

    ... from the NHLBI on Twitter. What Is a Pacemaker? A pacemaker is a small device that's placed in the ... the heart to beat at a normal rate. Pacemakers are used to treat arrhythmias (ah-RITH-me- ...

  4. 21 CFR 870.3630 - Pacemaker generator function analyzer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker generator function analyzer. 870.3630... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3630 Pacemaker generator function analyzer. (a) Identification. A pacemaker generator function analyzer is a device that is...

  5. 21 CFR 870.3720 - Pacemaker electrode function tester.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker electrode function tester. 870.3720... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3720 Pacemaker electrode function tester. (a) Identification. A pacemaker electrode function tester is a device which is...

  6. Influence of D-net (European GSM-Standard) cellular phones on pacemaker function in 50 patients with permanent pacemakers.

    Science.gov (United States)

    Wilke, A; Grimm, W; Funck, R; Maisch, B

    1996-10-01

    The widespread use of cellular phones in the last years has prompted some recent studies to suggest an interference of pacemaker function by cellular phone usage. To determine the risk of pacemaker patients using D-net cellular phones, we tested 50 patients with permanent pacemakers after routine pacemaker check by short phone calls using a cellular phone (Ericsson, D-net, frequency 890-915 MHz, digital information coding, equivalent to the European Groupe Systemes Mobiles standard). A six-channel surface ECG was continuously recorded from each patient to detect any interactions between pacemakers and cellular phones. Phone calls were repeated during the following pacemaker settings: (1) preexisting setting; (2) minimum ventricular rate of 90 beats/min and preexisting sensitivity; and (3) minimum ventricular rate of 90 beats/min and maximum sensitivity without T wave oversensing. Only 2 (4%) of 50 patients repeatedly showed intermittent pacemaker inhibition during calls with the cellular phone. Both pacemakers had unipolar sensing. Therefore, although interactions between cellular phone use and pacemaker function appear to be rare in our study, pacemaker dependent patients in particular should avoid the use of cellular phones.

  7. Self-powered cardiac pacemaker enabled by flexible single crystalline PMN-PT piezoelectric energy harvester.

    Science.gov (United States)

    Hwang, Geon-Tae; Park, Hyewon; Lee, Jeong-Ho; Oh, SeKwon; Park, Kwi-Il; Byun, Myunghwan; Park, Hyelim; Ahn, Gun; Jeong, Chang Kyu; No, Kwangsoo; Kwon, HyukSang; Lee, Sang-Goo; Joung, Boyoung; Lee, Keon Jae

    2014-07-23

    A flexible single-crystalline PMN-PT piezoelectric energy harvester is demonstrated to achieve a self-powered artificial cardiac pacemaker. The energy-harvesting device generates a short-circuit current of 0.223 mA and an open-circuit voltage of 8.2 V, which are enough not only to meet the standard for charging commercial batteries but also for stimulating the heart without an external power source.

  8. Identification and functional characterization of cardiac pacemaker cells in zebrafish.

    Directory of Open Access Journals (Sweden)

    Federico Tessadori

    Full Text Available In the mammalian heart a conduction system of nodes and conducting cells generates and transduces the electrical signals evoking myocardial contractions. Specialized pacemaker cells initiating and controlling cardiac contraction rhythmicity are localized in an anatomically identifiable structure of myocardial origin, the sinus node. We previously showed that in mammalian embryos sinus node cells originate from cardiac progenitors expressing the transcription factors T-box transcription factor 3 (Tbx3 and Islet-1 (Isl1. Although cardiac development and function are strikingly conserved amongst animal classes, in lower vertebrates neither structural nor molecular distinguishable components of a conduction system have been identified, questioning its evolutionary origin. Here we show that zebrafish embryos lacking the LIM/homeodomain-containing transcription factor Isl1 display heart rate defects related to pacemaker dysfunction. Moreover, 3D reconstructions of gene expression patterns in the embryonic and adult zebrafish heart led us to uncover a previously unidentified, Isl1-positive and Tbx2b-positive region in the myocardium at the junction of the sinus venosus and atrium. Through their long interconnecting cellular protrusions the identified Isl1-positive cells form a ring-shaped structure. In vivo labeling of the Isl1-positive cells by transgenic technology allowed their isolation and electrophysiological characterization, revealing their unique pacemaker activity. In conclusion we demonstrate that Isl1-expressing cells, organized as a ring-shaped structure around the venous pole, hold the pacemaker function in the adult zebrafish heart. We have thereby identified an evolutionary conserved, structural and molecular distinguishable component of the cardiac conduction system in a lower vertebrate.

  9. [Optimalization of rate adaptation using Holter functions in DDD/R pacemakers].

    Science.gov (United States)

    Novotný, T; Dvorák, R; Kozák, M; Vlasínová, J

    1998-06-01

    Introduction of the pacing rate adaptation according to the momentary metabolic needs added other programmable parametres which demand physician's attention during the initial postimplantation programmation and also in follow-up of pacemaker patients. The parametres setting is strictly individual with a need of feedback control. In some devices it is enabled by Holter functions as a part of pacemaker software. These methods were used to set the rate adaptive parametres in the group of 23 patients with implanted DDD/R pacemaker. The walking stress test was used. Model follow-up situations are presented in 3 case reports. Using Holter functions enables the physician to put patient's subjective complains in relation with actual heart rate--this is used to optimize the parametres of rate adaptation. The authors consider the Holter functions a necessary part of rate adaptive pacemaker software.

  10. Runtime Verification of Pacemaker Functionality Using Hierarchical Fuzzy Colored Petri-nets.

    Science.gov (United States)

    Majma, Negar; Babamir, Seyed Morteza; Monadjemi, Amirhassan

    2017-02-01

    Today, implanted medical devices are increasingly used for many patients and in case of diverse health problems. However, several runtime problems and errors are reported by the relevant organizations, even resulting in patient death. One of those devices is the pacemaker. The pacemaker is a device helping the patient to regulate the heartbeat by connecting to the cardiac vessels. This device is directed by its software, so any failure in this software causes a serious malfunction. Therefore, this study aims to a better way to monitor the device's software behavior to decrease the failure risk. Accordingly, we supervise the runtime function and status of the software. The software verification means examining limitations and needs of the system users by the system running software. In this paper, a method to verify the pacemaker software, based on the fuzzy function of the device, is presented. So, the function limitations of the device are identified and presented as fuzzy rules and then the device is verified based on the hierarchical Fuzzy Colored Petri-net (FCPN), which is formed considering the software limits. Regarding the experiences of using: 1) Fuzzy Petri-nets (FPN) to verify insulin pumps, 2) Colored Petri-nets (CPN) to verify the pacemaker and 3) To verify the pacemaker by a software agent with Petri-network based knowledge, which we gained during the previous studies, the runtime behavior of the pacemaker software is examined by HFCPN, in this paper. This is considered a developing step compared to the earlier work. HFCPN in this paper, compared to the FPN and CPN used in our previous studies reduces the complexity. By presenting the Petri-net (PN) in a hierarchical form, the verification runtime, decreased as 90.61% compared to the verification runtime in the earlier work. Since we need an inference engine in the runtime verification, we used the HFCPN to enhance the performance of the inference engine.

  11. Functional aspects of protein flexibility

    DEFF Research Database (Denmark)

    Teilum, Kaare; Olsen, Johan G; Kragelund, Birthe B

    2009-01-01

    Proteins are dynamic entities, and they possess an inherent flexibility that allows them to function through molecular interactions within the cell, among cells and even between organisms. Appreciation of the non-static nature of proteins is emerging, but to describe and incorporate...... this into an intuitive perception of protein function is challenging. Flexibility is of overwhelming importance for protein function, and the changes in protein structure during interactions with binding partners can be dramatic. The present review addresses protein flexibility, focusing on protein-ligand interactions....... The thermodynamics involved are reviewed, and examples of structure-function studies involving experimentally determined flexibility descriptions are presented. While much remains to be understood about protein flexibility, it is clear that it is encoded within their amino acid sequence and should be viewed...

  12. Function Machines & Flexible Algebraic Thought.

    Science.gov (United States)

    Davis, Gary E.; McGowen, Mercedes A.

    This paper explores how college students understand ideas of functions, and which representations are productive for them in promoting their ability to work flexibly across representations. The study used pre- and post-test scores, and triangulations via student self evaluations, to generate a hypothesis related to flexible thinking and success in…

  13. Transcription factor ISL1 is essential for pacemaker development and function.

    Science.gov (United States)

    Liang, Xingqun; Zhang, Qingquan; Cattaneo, Paola; Zhuang, Shaowei; Gong, Xiaohui; Spann, Nathanael J; Jiang, Cizhong; Cao, Xinkai; Zhao, Xiaodong; Zhang, Xiaoli; Bu, Lei; Wang, Gang; Chen, H S Vincent; Zhuang, Tao; Yan, Jie; Geng, Peng; Luo, Lina; Banerjee, Indroneal; Chen, Yihan; Glass, Christopher K; Zambon, Alexander C; Chen, Ju; Sun, Yunfu; Evans, Sylvia M

    2015-08-01

    The sinoatrial node (SAN) maintains a rhythmic heartbeat; therefore, a better understanding of factors that drive SAN development and function is crucial to generation of potential therapies, such as biological pacemakers, for sinus arrhythmias. Here, we determined that the LIM homeodomain transcription factor ISL1 plays a key role in survival, proliferation, and function of pacemaker cells throughout development. Analysis of several Isl1 mutant mouse lines, including animals harboring an SAN-specific Isl1 deletion, revealed that ISL1 within SAN is a requirement for early embryonic viability. RNA-sequencing (RNA-seq) analyses of FACS-purified cells from ISL1-deficient SANs revealed that a number of genes critical for SAN function, including those encoding transcription factors and ion channels, were downstream of ISL1. Chromatin immunoprecipitation assays performed with anti-ISL1 antibodies and chromatin extracts from FACS-purified SAN cells demonstrated that ISL1 directly binds genomic regions within several genes required for normal pacemaker function, including subunits of the L-type calcium channel, Ank2, and Tbx3. Other genes implicated in abnormal heart rhythm in humans were also direct ISL1 targets. Together, our results demonstrate that ISL1 regulates approximately one-third of SAN-specific genes, indicate that a combination of ISL1 and other SAN transcription factors could be utilized to generate pacemaker cells, and suggest ISL1 mutations may underlie sick sinus syndrome.

  14. Numerical models based on a minimal set of sarcolemmal electrogenic proteins and an intracellular Ca(2+) clock generate robust, flexible, and energy-efficient cardiac pacemaking.

    Science.gov (United States)

    Maltsev, Victor A; Lakatta, Edward G

    2013-06-01

    Recent evidence supports the idea that robust and, importantly, FLEXIBLE automaticity of cardiac pacemaker cells is conferred by a coupled system of membrane ion currents (an "M-clock") and a sarcoplasmic reticulum (SR)-based Ca(2+) oscillator ("Ca(2+)clock") that generates spontaneous diastolic Ca(2+) releases. This study identified numerical models of a human biological pacemaker that features robust and flexible automaticity generated by a minimal set of electrogenic proteins and a Ca(2+)clock. Following the Occam's razor principle (principle of parsimony), M-clock components of unknown molecular origin were excluded from Maltsev-Lakatta pacemaker cell model and thirteen different model types of only 4 or 5 components were derived and explored by a parametric sensitivity analysis. The extended ranges of SR Ca(2+) pumping (i.e. Ca(2+)clock performance) and conductance of ion currents were sampled, yielding a large variety of parameter combination, i.e. specific model sets. We tested each set's ability to simulate autonomic modulation of human heart rate (minimum rate of 50 to 70bpm; maximum rate of 140 to 210bpm) in response to stimulation of cholinergic and β-adrenergic receptors. We found that only those models that include a Ca(2+)clock (including the minimal 4-parameter model "ICaL+IKr+INCX+Ca(2+)clock") were able to reproduce the full range of autonomic modulation. Inclusion of If or ICaT decreased the flexibility, but increased the robustness of the models (a relatively larger number of sets did not fail during testing). The new models comprised of components with clear molecular identity (i.e. lacking IbNa & Ist) portray a more realistic pacemaking: A smaller Na(+) influx is expected to demand less energy for Na(+) extrusion. The new large database of the reduced coupled-clock numerical models may serve as a useful tool for the design of biological pacemakers. It will also provide a conceptual basis for a general theory of robust, flexible, and energy

  15. Numerical models based on a minimal set of sarcolemmal electrogenic proteins and an intracellular Ca2+ clock generate robust, flexible, and energy-efficient cardiac pacemaking

    Science.gov (United States)

    Maltsev, Victor A.; Lakatta, Edward G.

    2015-01-01

    Recent evidence supports the idea that robust and, importantly, FLEXIBLE automaticity of cardiac pacemaker cells is conferred by a coupled system of membrane ion currents (an “M-clock”) and a sarcoplasmic reticulum (SR)-based Ca2+ oscillator (“Ca2+clock”) that generates spontaneous diastolic Ca2+ releases. This study identified numerical models of a human biological pacemaker that features robust and flexible automaticity generated by a minimal set of electrogenic proteins and a Ca2+clock. Following the Occam’s razor principle (principle of parsimony), M-clock components of unknown molecular origin were excluded from Maltsev-Lakatta pacemaker cell model and thirteen different model types of only 4 or 5 components were derived and explored by a parametric sensitivity analysis. The extended ranges of SR Ca2+ pumping (i.e. Ca2+clock performance) and conductance of ion currents were sampled, yielding a large variety of parameter combination, i.e. specific model sets. We tested each set’s ability to simulate autonomic modulation of human heart rate (minimum rate of 50 to 70 bpm; maximum rate of 140 to 210 bpm) in response to stimulation of cholinergic and β-adrenergic receptors. We found that only those models that include a Ca2+clock (including the minimal 4-parameter model “ICaL+IKr+INCX+Ca2+clock”) were able to reproduce the full range of autonomic modulation. Inclusion of If or ICaT decreased the flexibility, but increased the robustness of the models (a relatively larger number of sets did not fail during testing). The new models comprised of components with clear molecular identity (i.e. lacking IbNa & Ist) portray a more realistic pacemaking: A smaller Na+ influx is expected to demand less energy for Na+ extrusion. The new large database of the reduced coupled-clock numerical models may serve as a useful tool for the design of biological pacemakers. It will also provide a conceptual basis for a general theory of robust, flexible, and energy

  16. Protein stability, flexibility and function

    DEFF Research Database (Denmark)

    Teilum, Kaare; Olsen, Johan G; Kragelund, Birthe B

    2011-01-01

    Proteins rely on flexibility to respond to environmental changes, ligand binding and chemical modifications. Potentially, a perturbation that changes the flexibility of a protein may interfere with its function. Millions of mutations have been performed on thousands of proteins in quests for a de......Proteins rely on flexibility to respond to environmental changes, ligand binding and chemical modifications. Potentially, a perturbation that changes the flexibility of a protein may interfere with its function. Millions of mutations have been performed on thousands of proteins in quests...... for a delineation of the molecular details of their function. Several of these mutations interfered with the binding of a specific ligand with a concomitant effect on the stability of the protein scaffold. It has been ambiguous and not straightforward to recognize if any relationships exist between the stability...... of a protein and the affinity for its ligand. In this review, we present examples of proteins where changes in stability results in changes in affinity and of proteins where stability and affinity are uncorrelated. We discuss the possibility for a relationship between stability and binding. From the data...

  17. A clinical evaluation of an improved Holter monitoring technique for artificial pacemaker function.

    Science.gov (United States)

    Kelen, G J; Bloomfield, D A; Hardage, M; Gomes, J A; Khan, R; Gopalaswamy, C; El Sherif, N

    1980-03-01

    This paper discusses shortcomings of conventional Holter monitoring in paced patients and describes a new technique which permits reliable detection of intermittent pacemaker malfunction and counts pacemaker activity during the recording period. Evaluation of the system of 64 consecutive patients revealed 15 with unsuspected episodic pacemaker dysfunction.

  18. Pacemaker (image)

    Science.gov (United States)

    A pacemaker is a small, battery-operated electronic device which is inserted under the skin to help the heart beat regularly and at an appropriate rate. The pacemaker has leads that travel through a large vein ...

  19. Modern perspectives on numerical modeling of cardiac pacemaker cell.

    Science.gov (United States)

    Maltsev, Victor A; Yaniv, Yael; Maltsev, Anna V; Stern, Michael D; Lakatta, Edward G

    2014-01-01

    Cardiac pacemaking is a complex phenomenon that is still not completely understood. Together with experimental studies, numerical modeling has been traditionally used to acquire mechanistic insights in this research area. This review summarizes the present state of numerical modeling of the cardiac pacemaker, including approaches to resolve present paradoxes and controversies. Specifically we discuss the requirement for realistic modeling to consider symmetrical importance of both intracellular and cell membrane processes (within a recent "coupled-clock" theory). Promising future developments of the complex pacemaker system models include the introduction of local calcium control, mitochondria function, and biochemical regulation of protein phosphorylation and cAMP production. Modern numerical and theoretical methods such as multi-parameter sensitivity analyses within extended populations of models and bifurcation analyses are also important for the definition of the most realistic parameters that describe a robust, yet simultaneously flexible operation of the coupled-clock pacemaker cell system. The systems approach to exploring cardiac pacemaker function will guide development of new therapies such as biological pacemakers for treating insufficient cardiac pacemaker function that becomes especially prevalent with advancing age.

  20. Modern Perspectives on Numerical Modeling of Cardiac Pacemaker Cell

    Science.gov (United States)

    Maltsev, Victor A.; Yaniv, Yael; Maltsev, Anna V.; Stern, Michael D.; Lakatta, Edward G.

    2015-01-01

    Cardiac pacemaking is a complex phenomenon that is still not completely understood. Together with experimental studies, numerical modeling has been traditionally used to acquire mechanistic insights in this research area. This review summarizes the present state of numerical modeling of the cardiac pacemaker, including approaches to resolve present paradoxes and controversies. Specifically we discuss the requirement for realistic modeling to consider symmetrical importance of both intracellular and cell membrane processes (within a recent “coupled-clock” theory). Promising future developments of the complex pacemaker system models include the introduction of local calcium control, mitochondria function, and biochemical regulation of protein phosphorylation and cAMP production. Modern numerical and theoretical methods such as multi-parameter sensitivity analyses within extended populations of models and bifurcation analyses are also important for the definition of the most realistic parameters that describe a robust, yet simultaneously flexible operation of the coupled-clock pacemaker cell system. The systems approach to exploring cardiac pacemaker function will guide development of new therapies, such as biological pacemakers for treating insufficient cardiac pacemaker function that becomes especially prevalent with advancing age. PMID:24748434

  1. In vivo biocompatibility and pacing function study of silver ion-based antimicrobial surface technology applied to cardiac pacemakers

    Science.gov (United States)

    Shawcross, James; Bakhai, Ameet; Ansaripour, Ali; Armstrong, James; Lewis, David; Agg, Philip; De Godoy, Roberta; Blunn, Gordon

    2017-01-01

    Introduction Evidence suggests that the rate of cardiovascular implantable electronic device (CIED) infections is increasing more rapidly than the rates of CIED implantation and is associated with considerable mortality, morbidity and health economic impact. Antimicrobial surface treatments are being developed for CIEDs to reduce the risk of postimplantation infection within the subcutaneous implant pocket. Methods and analysis The feasibility of processing cardiac pacemakers with the Agluna antimicrobial silver ion surface technology and in vivo biocompatibility were evaluated. Antimicrobially processed (n=6) and control pacemakers (n=6) were implanted into subcutaneous pockets and connected to a part of the sacrospinalis muscle using an ovine model for 12 weeks. Pacemaker function was monitored preimplantation and postimplantation. Results Neither local infection nor systemic toxicity were detected in antimicrobial or control devices, and surrounding tissues showed no abnormal pathology or over-reactivity. Semiquantitative scores of membrane formation, cellular orientation and vascularity were applied over five regions of the pacemaker capsule and average scores compared. Results showed no significant difference between antimicrobially processed and control pacemakers. Silver analysis of whole blood at 7 days found that levels were a maximum of 10 parts per billion (ppb) for one sample, more typically ≤2 ppb, compared with <<2 ppb for preimplantation levels, well below reported toxic levels. Conclusions There was no evidence of adverse or abnormal pathology in tissue surrounding antimicrobially processed pacemakers, or deleterious effect on basic pacing capabilities and parameters at 12 weeks. This proof of concept study provides evidence of basic biocompatibility and feasibility of applying this silver ion-based antimicrobial surface to a titanium pacemaker surface. PMID:28674615

  2. UNITY OF THE ORGANIZATIONAL FUNCTIONS FLEXIBILITY

    OpenAIRE

    George MOLDOVEANU; Cosmin DOBRIN

    2012-01-01

    The paper has the goal to analyse the correlation of the flexibility of all organizational functions. Based upon theoretical and practical studies, the decrease of flexibility into an "activity area" of organizations implies a diminution on a large scale of the flexibility of the processing system as a law expression of the decreasing outputs within economy. Therefore, at the level of each organizational function there are several major directions ensuring the flexibility of the "ensemble".

  3. Functional flexibility and team performance

    NARCIS (Netherlands)

    Molleman, E.; Slomp, J.

    1999-01-01

    This study deals with workforce flexibility defined in terms of 'multifunctionality' and 'redundancy'. These concepts refer, respectively, to the number of different tasks a worker has mastered and the number of workers that are qualified to do a specific task. A third factor to be considered is wor

  4. Evaluation of left ventricular longitudinal function and synchrony after dual chamber pacemaker implantation

    Directory of Open Access Journals (Sweden)

    Kristina Baronaitė-Dūdonienė

    2014-01-01

    Conclusions: Global longitudinal strain and LV dyssynchrony assessment enables us to detect early signs of LV dysfunction. Mechanisms of dyssynchrony development will be useful for pacemaker programing choices in order to prevent further dyssynchronisation.

  5. Functional flexibility in wild bonobo vocal behaviour

    Directory of Open Access Journals (Sweden)

    Zanna Clay

    2015-08-01

    Full Text Available A shared principle in the evolution of language and the development of speech is the emergence of functional flexibility, the capacity of vocal signals to express a range of emotional states independently of context and biological function. Functional flexibility has recently been demonstrated in the vocalisations of pre-linguistic human infants, which has been contrasted to the functionally fixed vocal behaviour of non-human primates. Here, we revisited the presumed chasm in functional flexibility between human and non-human primate vocal behaviour, with a study on our closest living primate relatives, the bonobo (Pan paniscus. We found that wild bonobos use a specific call type (the “peep” across a range of contexts that cover the full valence range (positive-neutral-negative in much of their daily activities, including feeding, travel, rest, aggression, alarm, nesting and grooming. Peeps were produced in functionally flexible ways in some contexts, but not others. Crucially, calls did not vary acoustically between neutral and positive contexts, suggesting that recipients take pragmatic information into account to make inferences about call meaning. In comparison, peeps during negative contexts were acoustically distinct. Our data suggest that the capacity for functional flexibility has evolutionary roots that predate the evolution of human speech. We interpret this evidence as an example of an evolutionary early transition away from fixed vocal signalling towards functional flexibility.

  6. Left Ventricular Synchrony and Function in Pediatric Patients with Definitive Pacemakers

    Science.gov (United States)

    Ortega, Michel Cabrera; Morejón, Adel Eladio Gonzales; Ricardo, Giselle Serrano

    2013-01-01

    Background Chronic right ventricular pacing (RVP) induces a dyssynchronous contraction pattern, producing interventricular and intraventricular asynchrony. Many studies have shown the relationship of RVP with impaired left ventricular (LV) form and function. Objective The aim of this study was to evaluate LV synchrony and function in pediatric patients receiving RVP in comparison with those receiving LV pacing (LVP). Methods LV systolic and diastolic function and synchrony were evaluated in 80 pediatric patients with either nonsurgical or postsurgical complete atrioventricular block, with pacing from either the RV endocardium (n = 40) or the LV epicardium (n = 40). Echocardiographic data obtained before pacemaker implantation, immediately after it, and at the end of a mean follow-up of 6.8 years were analyzed. Results LV diastolic function did not change in any patient during follow-up. LV systolic function was preserved in patients with LVP. However, in children with RVP the shortening fraction and ejection fraction decreased from medians of 41% ± 2.6% and 70% ± 6.9% before implantation to 32% ± 4.2% and 64% ± 2.5% (p < 0.0001 and p < 0.0001), respectively, at final follow-up. Interventricular mechanical delay was significantly larger with RVP (66 ± 13 ms) than with LVP (20 ± 8 ms). Similarly, the following parameters were significantly different in the two groups: LV mechanical delay (RVP: 69 ± 6 ms, LVP: 30 ± 11 ms, p < 0.0001); septal to lateral wall motion delay (RVP: 75 ± 19 ms, LVP: 42 ± 10 ms, p < 0.0001); and, septal to posterior wall motion delay (RVP: 127 ± 33 ms, LVP: 58 ± 17 ms, p < 0.0001). Conclusion Compared with RV endocardium, LV epicardium is an optimal site for pacing to preserve cardiac synchrony and function. PMID:24061683

  7. Distribution of pacemaker function through the tunica muscularis of the canine gastric antrum.

    Science.gov (United States)

    Horiguchi, K; Semple, G S; Sanders, K M; Ward, S M

    2001-11-15

    1. Interstitial cells of Cajal (ICC) have been shown to generate pacemaker activity in gastrointestinal (GI) muscles. Experiments were performed to characterize the ICC within the canine gastric antrum and to determine the site(s) of pacemaker activity and whether active propagation pathways exist within the thick-walled tunica muscularis of large mammals. 2. Immunohistochemistry and electron microscopy revealed four populations of ICC within the antral muscularis on the basis of anatomical location. Typical ICC were found in the myenteric region of the small intestine (IC-MY). Intramuscular ICC (IC-IM) were intermingled between muscle fibres of circular and longitudinal muscle layers. ICC were also found within septa (IC-SEP) between muscle bundles and along the submucosal surface of the circular muscle layer (IC-SM). ICC were identified in each location by ultrastructural features. 3. Intracellular electrical recordings demonstrated nifedipine-insensitive slow waves throughout the circular muscle layer. Separation of interior and submucosal circular muscle strips from the dominant (myenteric) pacemaker region dramatically slowed frequency but did not block spontaneous slow waves, suggesting that pacemaker cells populate all regions of the circular muscle. 4. Slow waves could be evoked in interior and submucosal circular muscles at rates above normal antral frequency by electrical pacing or by acetylcholine (0.3 microM). Active slow wave propagation occurred in all regions of the circular muscle, and propagation velocities were similar in each region. 5. In summary, antral muscles of the canine stomach have pacemaker capability throughout the circular muscle. Normally, a dominant pacemaker near the myenteric plexus drives slow waves that actively propagate throughout the circular layer. Pacemaker activity and the active propagation pathway may occur in networks of ICC that are distributed in the region of the myenteric plexus and throughout the circular muscle

  8. Ca2+-Clock-Dependent Pacemaking in the Sinus Node Is Impaired in Mice with a Cardiac Specific Reduction in SERCA2 Abundance

    Science.gov (United States)

    Logantha, Sunil Jit R. J.; Stokke, Mathis K.; Atkinson, Andrew J.; Kharche, Sanjay R.; Parveen, Sajida; Saeed, Yawer; Sjaastad, Ivar; Sejersted, Ole M.; Dobrzynski, Halina

    2016-01-01

    Background: The sarcoplasmic reticulum Ca2+-ATPase (SERCA2) pump is an important component of the Ca2+-clock pacemaker mechanism that provides robustness and flexibility to sinus node pacemaking. We have developed transgenic mice with reduced cardiac SERCA2 abundance (Serca2 KO) as a model for investigating SERCA2's role in sinus node pacemaking. Methods and Results: In Serca2 KO mice, ventricular SERCA2a protein content measured by Western blotting was 75% (P 70% reduction in SERCA2 activity. Conclusions: Serca2 KO mice show a disrupted Ca2+-clock-dependent pacemaker mechanism contributing to impaired sinus node and atrioventricular node function. PMID:27313537

  9. [New pacemaker functions: which ones represent real progress and which are only gadgets?].

    Science.gov (United States)

    Dodinot, B

    2000-07-01

    Modern pacemakers, and particularly dual chamber models, include a broad array of therapeutic and diagnostic features. Some are designed to increase safety, whereas others are either designed to avoid unnecessary pacing, reduce the current drain and increase the pacemaker longevity, or to improve the hemodynamics. Diagnostic features are more elaborate, more or less automatic, and easier to extract from the pacemaker memory. Some of these new algorithms represent a real advantage, while others appear to be more like gadgets than real advances. Several new algorithms should be improved in order to avoid possibly dangerous side effects. Most of these new features are of little value in the absence of postoperative programming by a well trained physician.

  10. Functional Capacity of Patients with Pacemaker Due to Isolated Congenital Atrioventricular Block

    Directory of Open Access Journals (Sweden)

    Roberto Márcio de Oliveira Júnior

    2015-01-01

    Full Text Available Background: Isolated congenital atrioventricular block (CAVB is a rare condition with multiple clinical outcomes. Ventricular remodeling can occur in approximately 10% of the patients after pacemaker (PM implantation. Objectives: To assess the functional capacity of children and young adults with isolated CAVB and chronic pacing of the right ventricle (RV and evaluate its correlation with predictors of ventricular remodeling. Methods: This cross-sectional study used a cohort of patients with isolated CAVB and RV pacing for over a year. The subjects underwent clinical and echocardiographic evaluation. Functional capacity was assessed using the six-minute walk test. Chi-square test, Fisher's exact test, and Pearson correlation coefficient were used, considering a significance level of 5%. Results: A total of 61 individuals were evaluated between March 2010 and December 2013, of which 67.2% were women, aged between 7 and 41 years, who were using PMs for 13.5 ± 6.3 years. The percentage of ventricular pacing was 97.9 ± 4.1%, and the duration of the paced QRS complex was 153.7 ± 19.1 ms. Majority of the subjects (95.1% were asymptomatic and did not use any medication. The mean distance walked was 546.9 ± 76.2 meters and was strongly correlated with the predicted distance (r = 0.907, p = 0.001 but not with risk factors for ventricular remodeling. (Arq Bras Cardiol. 2014; [online].ahead print, PP.0-0 Conclusions: The functional capacity of isolated CAVB patients with chronic RV pacing was satisfactory but did not correlate with risk factors for ventricular remodeling.

  11. Functional Capacity of Patients with Pacemaker Due to Isolated Congenital Atrioventricular Block

    Science.gov (United States)

    de Oliveira Júnior, Roberto Márcio; da Silva, Kátia Regina; Kawauchi, Tatiana Satie; Alves, Lucas Bassolli de Oliveira; Crevelari, Elizabeth Sartori; Martinelli, Martino; Costa, Roberto

    2015-01-01

    Background Isolated congenital atrioventricular block (CAVB) is a rare condition with multiple clinical outcomes. Ventricular remodeling can occur in approximately 10% of the patients after pacemaker (PM) implantation. Objectives To assess the functional capacity of children and young adults with isolated CAVB and chronic pacing of the right ventricle (RV) and evaluate its correlation with predictors of ventricular remodeling. Methods This cross-sectional study used a cohort of patients with isolated CAVB and RV pacing for over a year. The subjects underwent clinical and echocardiographic evaluation. Functional capacity was assessed using the six-minute walk test. Chi-square test, Fisher's exact test, and Pearson correlation coefficient were used, considering a significance level of 5%. Results A total of 61 individuals were evaluated between March 2010 and December 2013, of which 67.2% were women, aged between 7 and 41 years, who were using PMs for 13.5 ± 6.3 years. The percentage of ventricular pacing was 97.9 ± 4.1%, and the duration of the paced QRS complex was 153.7 ± 19.1 ms. Majority of the subjects (95.1%) were asymptomatic and did not use any medication. The mean distance walked was 546.9 ± 76.2 meters and was strongly correlated with the predicted distance (r = 0.907, p = 0.001) but not with risk factors for ventricular remodeling. Conclusions The functional capacity of isolated CAVB patients with chronic RV pacing was satisfactory but did not correlate with risk factors for ventricular remodeling. PMID:25387405

  12. Concealed malfunction of the temporary pacemaker

    Directory of Open Access Journals (Sweden)

    Mohammad Alasti

    2006-04-01

    Full Text Available The 12-lead ECG shows sequential atrial and ventricular pacing (Figure 1A. A tracing, obtained simultaneously during pacemaker interrogation, disclosed pacemaker functioning as VDD mode (Figure 1B. The careful examination of this pacemaker tracing showed that there is a pacing stimulus before each P wave (compatible with DDD mode. This paradox can only be explained by displacement of the temporary pacing lead to right atrium and right atrial stimulation by temporary pacemaker. In this setting, each temporary pacemaker-induced atrial depolarization is tracked by the right atrial lead of the permanent pacemaker as intrinsic P wave. Fluoroscopic study confirmed this explanation (Figure 2. The displaced temporary pacing lead was seen near the lateral right atrial wall. Temporary pacemaker lead had been inserted before replacement of permanent pacemaker.

  13. Trends in Cardiac Pacemaker Batteries

    Directory of Open Access Journals (Sweden)

    Venkateswara Sarma Mallela

    2004-10-01

    Full Text Available Batteries used in Implantable cardiac pacemakers-present unique challenges to their developers and manufacturers in terms of high levels of safety and reliability. In addition, the batteries must have longevity to avoid frequent replacements. Technological advances in leads/electrodes have reduced energy requirements by two orders of magnitude. Micro-electronics advances sharply reduce internal current drain concurrently decreasing size and increasing functionality, reliability, and longevity. It is reported that about 600,000 pacemakers are implanted each year worldwide and the total number of people with various types of implanted pacemaker has already crossed 3 million. A cardiac pacemaker uses half of its battery power for cardiac stimulation and the other half for housekeeping tasks such as monitoring and data logging. The first implanted cardiac pacemaker used nickel-cadmium rechargeable battery, later on zinc-mercury battery was developed and used which lasted for over 2 years. Lithium iodine battery invented and used by Wilson Greatbatch and his team in 1972 made the real impact to implantable cardiac pacemakers. This battery lasts for about 10 years and even today is the power source for many manufacturers of cardiac pacemakers. This paper briefly reviews various developments of battery technologies since the inception of cardiac pacemaker and presents the alternative to lithium iodine battery for the near future.

  14. Effectiveness of pacemaker tele-monitoring on quality of life, functional capacity, event detection and workload: The PONIENTE trial.

    Science.gov (United States)

    Lopez-Villegas, Antonio; Catalan-Matamoros, Daniel; Robles-Musso, Emilio; Peiro, Salvador

    2016-11-01

    The purpose of the present study was to assess the effectiveness of the remote monitoring (RM) of older adults with pacemakers on health-related quality of life, functional capacity, feasibility, reliability and safety. The PONIENTE study is a controlled, non-randomized, non-blinded clinical trial, with data collection carried out during the pre-implant stage and after 12 months. Between October of 2012 and November of 2013, 82 patients were assigned to either a remote monitoring group (n = 30) or a conventional hospital monitoring (HM) group (n = 52). The EuroQol-5D (EQ-5D) and the Duke Activity Status Index were used to measure health-related quality of life and functional capacity, respectively. Baseline characteristics and number of hospital visits were also analyzed. The baseline characteristics of the two study groups were similar for both the EQ-5D (RM 0.74, HM 0.67; P = 0.404) and the Duke Activity Status Index (RM 21.42, HM 19.95; P = 0.272). At the 12-month follow up, the EQ-5D utility score was improved for both groups (RM 0.91, HM 0.81; P = 0.154), unlike the EQ-5D Visual Analog Scale (P = 0.043). The Duke Activity Status Index score was similar to the baseline score. The number of in-hospital visits was 27% lower (3 vs 4; P pacemakers in older adults is an equivalent option to hospital monitoring, in terms of health-related quality of life and functional capacity. Furthermore, it allows for the early detection of clinical and pacemaker-related adverse events, and significantly reduces the number of in-hospital visits. Geriatr Gerontol Int 2016; 16: 1188-1195. © 2015 Japan Geriatrics Society.

  15. One-year cardiac morphological and functional evolution following permanent pacemaker implantation in right ventricular septal position in chagasic patients

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    Otaviano da Silva Júnior

    2012-06-01

    Full Text Available INTRODUCTION: The septal position is an alternative site for cardiac pacing (CP that is potentially less harmful to cardiac function. METHODS: Patients with Chagas disease without heart failure submitted to permanent pacemaker (PP implantation at the Clinics Hospital of the Triângulo Mineiro Federal University (UFTM, were selected from February 2009 to February 2010. The parameters analyzed were ventricular remodeling, the degree of electromechanical dyssynchrony (DEM, exercise time and VO2 max during exercise testing (ET and functional class (NYHA. Echocardiography was performed 24 to 48h following implantation and after one year follow-up. The patients were submitted to ET one month postprocedure and at the end of one year. RESULTS: Thirty patients were included. Patient mean age was 59±13 years-old. Indication for PP implantation was complete atrioventricular (AV block in 22 (73.3% patients and 2nd degree AV block in the other eight (26.7%. All patients were in NYHA I and no changes occurred in the ET parameters. No variations were detected in echocardiographic remodeling measurements. Intraventricular dyssynchrony was observed in 46.6% of cases and interventricular dyssynchrony in 33.3% of patients after one year. CONCLUSIONS: The findings of this work suggest that there is not significant morphological and functional cardiac change following pacemaker implantation in septal position in chagasic patients with normal left ventricular function after one year follow-up. Thus, patients may remain asymptomatic, presenting maintenance of functional capacity and no left ventricular remodeling.

  16. Functional flexibility good for skills development

    NARCIS (Netherlands)

    Houtman, I.L.D.

    2004-01-01

    Functional flexibility, making optimal use of the employee’s capacity to perform different tasks, is positively related to skills development and involvement in decision-making. It may lead to emotional exhaustion, however, if an imbalance exists, such as high job demands combined with a lack of

  17. 21 CFR 870.3680 - Cardiovascular permanent or temporary pacemaker electrode.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiovascular permanent or temporary pacemaker... § 870.3680 Cardiovascular permanent or temporary pacemaker electrode. (a) Temporary pacemaker electrode—(1) Identification. A temporary pacemaker electrode is a device consisting of flexible insulated...

  18. Pacemaker patients’ perspective and experiences in a pacemaker outpatient clinic in relation to test intervals of the pacemaker

    DEFF Research Database (Denmark)

    Lauberg, Astrid; Hansen, Tina; Pedersen, Trine Pernille Dahl

    the pacemaker and psychological reactions. Patients with pacemakers older than 3 months lacked communication with fellowmen. Conclusion The patients express receiving competent and professional treatment when visiting the outpatient clinic, there seems to be a discrepancy between the long test intervals......In and out in 15 minutes! Shorttime nursing in an outpatient clinic Pacemaker patients’ perspective and experiences in a pacemaker outpatient clinic in relation to test intervals of the pacemaker. Background Pacemaker implantation is a highly documented treatment for patients with bradycardia...... an evident decline in quality of life regarding psychological and social aspects 6 month after the implantation in terms of cognitive function, work ability, and sexual activity. Mlynarski et al (2009) have found correlations between pacemaker implantation and anxiety and depression. Aim The aim...

  19. Do media players cause interference with pacemakers?

    Science.gov (United States)

    Thaker, Jay P; Patel, Mehul B; Shah, Ashok J; Liepa, Valdis V; Brunett, Joseph D; Jongnarangsin, Krit; Gardiner, Joseph C; Thakur, Ranjan

    2009-11-01

    Electrical devices generate electromagnetic fields that may interfere with pacemakers. Media players cause telemetry interference with pacemakers, but it is not known whether they cause direct interference with pacemakers. The purpose of this study was to examine the interaction between pacemakers and 3 different media players. In this prospective, randomized study, 54 patients with dual chamber pacemakers who were in sinus rhythm underwent baseline observation, followed by observation under telemetry communication. These patients were then randomly evaluated with 3 media players (iPod 3G, iPod Photo, and iPod Touch Apple, Cupertino, CA) with and without telemetry communication for 1 minute each. Patients were monitored for pacemaker malfunction using a single-channel ECG during exposure to media players. The pacemaker was interrogated after each exposure and an interrogation report was printed for evaluation. Pacemaker interference was categorized as type I, II, or III. Types I and II interference described telemetry interference and type III interference was defined as any direct interference with pacemaker function or programmed parameters. A total of 54 patients (29 men and 25 women; mean age 77.2 +/- 9.3 y) were evaluated. In total, of the 162 tests (for telemetry interference) 36.4% were positive (Type I and II). Type III interference was also evaluated in 162 tests and none showed any evidence of direct interference. Media players cause telemetry interference with pacemakers, but they do not directly interfere with pacemaker function.

  20. AV interval optimization using pressure volume loops in dual chamber pacemaker patients with maintained systolic left ventricular function.

    Science.gov (United States)

    Eberhardt, Frank; Hanke, Thorsten; Fitschen, Joern; Heringlake, Matthias; Bode, Frank; Schunkert, Heribert; Wiegand, Uwe K H

    2012-08-01

    Atrioventricular (AV) interval optimization is often deemed too time-consuming in dual-chamber pacemaker patients with maintained LV function. Thus the majority of patients are left at their default AV interval. To quantify the magnitude of hemodynamic improvement following AV interval optimization in chronically paced dual chamber pacemaker patients. A pressure volume catheter was placed in the left ventricle of 19 patients with chronic dual chamber pacing and an ejection fraction >45 % undergoing elective coronary angiography. AV interval was varied in 10 ms steps from 80 to 300 ms, and pressure volume loops were recorded during breath hold. The average optimal AV interval was 152 ± 39 ms compared to 155 ± 8 ms for the average default AV interval (range 100-240 ms). The average improvement in stroke work following AV interval optimization was 935 ± 760 mmHg/ml (range 0-2,908; p AV interval changes the average stroke work by 207 ± 162 mmHg/ml. AV interval optimization also leads to improved systolic dyssynchrony indices (17.7 ± 7.0 vs. 19.4 ± 7.1 %; p = 0.01). The overall hemodynamic effect of AV interval optimization in patients with maintained LV function is in the same range as for patients undergoing cardiac resynchronization therapy for several parameters. The positive effect of AV interval optimization also applies to patients who have been chronically paced for years.

  1. Mechanisms of Beat-to-Beat Regulation of Cardiac Pacemaker Cell Function by Ca2+ Cycling Dynamics

    Science.gov (United States)

    Yaniv, Yael; Stern, Michael D.; Lakatta, Edward G.; Maltsev, Victor A.

    2013-01-01

    Whether intracellular Ca2+ cycling dynamics regulate cardiac pacemaker cell function on a beat-to-beat basis remains unknown. Here we show that under physiological conditions, application of low concentrations of caffeine (2–4 mM) to isolated single rabbit sinoatrial node cells acutely reduces their spontaneous action potential cycle length (CL) and increases Ca2+ transient amplitude for several cycles. Numerical simulations, using a modified Maltsev-Lakatta coupled-clock model, faithfully reproduced these effects, and also the effects of CL prolongation and dysrhythmic spontaneous beating (produced by cytosolic Ca2+ buffering) and an acute CL reduction (produced by flash-induced Ca2+ release from a caged Ca2+ buffer), which we had reported previously. Three contemporary numerical models (including the original Maltsev-Lakatta model) failed to reproduce the experimental results. In our proposed new model, Ca2+ releases acutely change the CL via activation of the Na+/Ca2+ exchanger current. Time-dependent CL reductions after flash-induced Ca2+ releases (the memory effect) are linked to changes in Ca2+ available for pumping into sarcoplasmic reticulum which, in turn, changes the sarcoplasmic reticulum Ca2+ load, diastolic Ca2+ releases, and Na+/Ca2+ exchanger current. These results support the idea that Ca2+ regulates CL in cardiac pacemaker cells on a beat-to-beat basis, and suggest a more realistic numerical mechanism of this regulation. PMID:24094396

  2. Mechanisms of beat-to-beat regulation of cardiac pacemaker cell function by Ca²⁺ cycling dynamics.

    Science.gov (United States)

    Yaniv, Yael; Stern, Michael D; Lakatta, Edward G; Maltsev, Victor A

    2013-10-01

    Whether intracellular Ca(2+) cycling dynamics regulate cardiac pacemaker cell function on a beat-to-beat basis remains unknown. Here we show that under physiological conditions, application of low concentrations of caffeine (2-4 mM) to isolated single rabbit sinoatrial node cells acutely reduces their spontaneous action potential cycle length (CL) and increases Ca(2+) transient amplitude for several cycles. Numerical simulations, using a modified Maltsev-Lakatta coupled-clock model, faithfully reproduced these effects, and also the effects of CL prolongation and dysrhythmic spontaneous beating (produced by cytosolic Ca(2+) buffering) and an acute CL reduction (produced by flash-induced Ca(2+) release from a caged Ca(2+) buffer), which we had reported previously. Three contemporary numerical models (including the original Maltsev-Lakatta model) failed to reproduce the experimental results. In our proposed new model, Ca(2+) releases acutely change the CL via activation of the Na(+)/Ca(2+) exchanger current. Time-dependent CL reductions after flash-induced Ca(2+) releases (the memory effect) are linked to changes in Ca(2+) available for pumping into sarcoplasmic reticulum which, in turn, changes the sarcoplasmic reticulum Ca(2+) load, diastolic Ca(2+) releases, and Na(+)/Ca(2+) exchanger current. These results support the idea that Ca(2+) regulates CL in cardiac pacemaker cells on a beat-to-beat basis, and suggest a more realistic numerical mechanism of this regulation.

  3. Regulation of basal and reserve cardiac pacemaker function by interactions of cAMP mediated PKA-dependent Ca2+ cycling with surface membrane channels

    Science.gov (United States)

    Vinogradova, Tatiana M.; Lakatta, Edward G.

    2009-01-01

    Decades of intensive research of primary cardiac pacemaker, the sinoatrial node, have established potential roles of specific membrane channels in the generation of the diastolic depolarization, the major mechanism allowing sinoatrial node cells generate spontaneous beating. During the last three decades, multiple studies made either in the isolated sinoatrial node or sinoatrial node cells have demonstrated a pivotal role of Ca2+ and, specifically Ca2+-release from sarcoplasmic reticulum, for spontaneous beating of cardiac pacemaker. Recently, spontaneous, rhythmic local subsarcolemmal Ca2+ releases from ryanodine receptors during late half of the diastolic depolarization have been implicated as a vital factor in the generation of sinoatrial node cells spontaneous firing. Local Ca2+ releases are driven by a unique combination of high basal cAMP production by adenylyl cyclases, high basal cAMP degradation by phosphodiesterases and a high level of cAMP-mediated PKA-dependent phosphorylation. These local Ca2+ releases activate an inward Na+-Ca2+ exchange current which accelerates the terminal diastolic depolarization rate and, thus, controls the spontaneous pacemaker firing. Both the basal primary pacemaker beating rate and its modulation via β-adrenergic receptor stimulation appear to be critically dependent upon intact RyR function and local subsarcolemmal sarcoplasmic reticulum generated Ca2+ releases. This review aspires to integrate the traditional viewpoint that has emphasized the supremacy of the ensemble of surface membrane ion channels in spontaneous firing of the primary cardiac pacemaker, and these novel perspectives of cAMP-mediated PKA-dependent Ca2+ cycling in regulation of the heart pacemaker clock, both in the basal state and during β-adrenergic receptor stimulation. PMID:19573534

  4. Pacemaker patients’ perspective and experiences in a pacemaker outpatient clinic in relation to test intervals of the pacemaker

    DEFF Research Database (Denmark)

    Lauberg, Astrid; Hansen, Tina; Pedersen, Trine Pernille Dahl

    In and out in 15 minutes! Shorttime nursing in an outpatient clinic Pacemaker patients’ perspective and experiences in a pacemaker outpatient clinic in relation to test intervals of the pacemaker. Background Pacemaker implantation is a highly documented treatment for patients with bradycardia....... In Aalborg University Hospital pacemakers are tested when implanted, 3 months later and then two years after the implantation. It is tested by a nurse specialist who also is interested in the patient’s general health status and well being. Patient expectations are unknown. Cheng et al (2002) have found...... an evident decline in quality of life regarding psychological and social aspects 6 month after the implantation in terms of cognitive function, work ability, and sexual activity. Mlynarski et al (2009) have found correlations between pacemaker implantation and anxiety and depression. Aim The aim...

  5. On the Evolution of the Cardiac Pacemaker

    Directory of Open Access Journals (Sweden)

    Silja Burkhard

    2017-04-01

    Full Text Available The rhythmic contraction of the heart is initiated and controlled by an intrinsic pacemaker system. Cardiac contractions commence at very early embryonic stages and coordination remains crucial for survival. The underlying molecular mechanisms of pacemaker cell development and function are still not fully understood. Heart form and function show high evolutionary conservation. Even in simple contractile cardiac tubes in primitive invertebrates, cardiac function is controlled by intrinsic, autonomous pacemaker cells. Understanding the evolutionary origin and development of cardiac pacemaker cells will help us outline the important pathways and factors involved. Key patterning factors, such as the homeodomain transcription factors Nkx2.5 and Shox2, and the LIM-homeodomain transcription factor Islet-1, components of the T-box (Tbx, and bone morphogenic protein (Bmp families are well conserved. Here we compare the dominant pacemaking systems in various organisms with respect to the underlying molecular regulation. Comparative analysis of the pathways involved in patterning the pacemaker domain in an evolutionary context might help us outline a common fundamental pacemaker cell gene programme. Special focus is given to pacemaker development in zebrafish, an extensively used model for vertebrate development. Finally, we conclude with a summary of highly conserved key factors in pacemaker cell development and function.

  6. Epithermal neutron beam interference with cardiac pacemakers

    Energy Technology Data Exchange (ETDEWEB)

    Koivunoro, H., E-mail: hanna.koivunoro@helsinki.fi [Department of Physics, P.O.B. 64, FI-00014 University of Helsinki (Finland)] [Department of Oncology, Helsinki University Central Hospital, P.O.B. 180, FIN-00029 HUS (Finland)] [Boneca Corporation, Finland, Filnland (Finland); Seren, T. [VTT Technical Research Centre of Finland (Finland); Hyvoenen, H. [Boneca Corporation, Finland, Filnland (Finland); Kotiluoto, P. [VTT Technical Research Centre of Finland (Finland); Iivonen, P. [St. Jude Medical (Finland); Auterinen, I. [VTT Technical Research Centre of Finland (Finland); Seppaelae, T.; Kankaanranta, L. [Department of Oncology, Helsinki University Central Hospital, P.O.B. 180, FIN-00029 HUS (Finland); Pakarinen, S. [Department of Cardiology, Helsinki University Central Hospital (Finland); Tenhunen, M. [Department of Oncology, Helsinki University Central Hospital, P.O.B. 180, FIN-00029 HUS (Finland); Savolainen, S. [HUS Helsinki Medical Imaging Center, Helsinki University Central Hospital (Finland)

    2011-12-15

    In this paper, a phantom study was performed to evaluate the effect of an epithermal neutron beam irradiation on the cardiac pacemaker function. Severe malfunction occurred in the pacemakers after substantially lower dose from epithermal neutron irradiation than reported in the fast neutron or photon beams at the same dose rate level. In addition the pacemakers got activated, resulting in nuclides with half-lives from 25 min to 115 d. We suggest that BNCT should be administrated only after removal of the pacemaker from the vicinity of the tumor.

  7. Dislocation of a non-functional transvenous ventricular pacemaker lead in a child 6 years following abandonment.

    Science.gov (United States)

    Nagel, Bert; Koestenberger, Martin; Knez, Igor; Gamillscheg, Andreas

    2010-11-01

    This case report describes for the first time a late dislocation of an abandoned transvenous ventricular pacemaker (PM) lead in a child. Further management of this complication and the importance for follow-up of PM leads are discussed.

  8. A central pacemaker that underlies the production of seasonal and sexually dimorphic social signals: functional aspects revealed by glutamate stimulation.

    Science.gov (United States)

    Quintana, Laura; Sierra, Felipe; Silva, Ana; Macadar, Omar

    2011-02-01

    The cyclic enrichment of behavioral repertoires is a common event in seasonal breeders. Breeding males Brachyhypopomus gauderio produce electric organ discharge (EOD) rate modulations called chirps while females respond with interruptions. The electromotor system is commanded by a pacemaker nucleus (PN) which sets the basal rate and produces the rate modulations. We focused on identifying functional, seasonal and sexual differences in this nucleus in correlation to these differences in behavior. The in vivo response to glutamate injection in the PN was seasonal, sexually dimorphic and site specific. Non-breeding adults and breeding females injected in dorsal and ventral sites generated EOD rate increases and interruptions, respectively. Reproductive males added a conspicuous communication signal to this repertoire. They chirped repetitively when we injected glutamate in a very restricted area of the ventral-rostral nucleus, surprisingly one with a low number of relay cell somata. This study shows that the PN is functionally organized in regions in a caudal-rostral axis, besides the previously documented dorsal-ventral division. Functional regions are revealed by seasonal changes that annually provide this nucleus with the cellular mechanisms that allow the bursting activity underlying chirp production, only in males.

  9. Heart pacemaker - discharge

    Science.gov (United States)

    ... pacemaker can be used for patients with heart failure. It has three leads to help the heart beat in a more coordinated manner. Some pacemakers also can deliver electric shocks to the heart that can stop life-threatening ...

  10. Wiggle-predicting functionally flexible regions from primary sequence.

    Directory of Open Access Journals (Sweden)

    Jenny Gu

    2006-07-01

    Full Text Available The Wiggle series are support vector machine-based predictors that identify regions of functional flexibility using only protein sequence information. Functionally flexible regions are defined as regions that can adopt different conformational states and are assumed to be necessary for bioactivity. Many advances have been made in understanding the relationship between protein sequence and structure. This work contributes to those efforts by making strides to understand the relationship between protein sequence and flexibility. A coarse-grained protein dynamic modeling approach was used to generate the dataset required for support vector machine training. We define our regions of interest based on the participation of residues in correlated large-scale fluctuations. Even with this structure-based approach to computationally define regions of functional flexibility, predictors successfully extract sequence-flexibility relationships that have been experimentally confirmed to be functionally important. Thus, a sequence-based tool to identify flexible regions important for protein function has been created. The ability to identify functional flexibility using a sequence based approach complements structure-based definitions and will be especially useful for the large majority of proteins with unknown structures. The methodology offers promise to identify structural genomics targets amenable to crystallization and the possibility to engineer more flexible or rigid regions within proteins to modify their bioactivity.

  11. Flexible hydrogel-based functional composite materials

    Science.gov (United States)

    Song, Jie; Saiz, Eduardo; Bertozzi, Carolyn R; Tomasia, Antoni P

    2013-10-08

    A composite having a flexible hydrogel polymer formed by mixing an organic phase with an inorganic composition, the organic phase selected from the group consisting of a hydrogel monomer, a crosslinker, a radical initiator, and/or a solvent. A polymerization mixture is formed and polymerized into a desired shape and size.

  12. Drosophila Clock Is Required in Brain Pacemaker Neurons to Prevent Premature Locomotor Aging Independently of Its Circadian Function.

    Directory of Open Access Journals (Sweden)

    Alexandra Vaccaro

    2017-01-01

    Full Text Available Circadian clocks control many self-sustained rhythms in physiology and behavior with approximately 24-hour periodicity. In many organisms, oxidative stress and aging negatively impact the circadian system and sleep. Conversely, loss of the clock decreases resistance to oxidative stress, and may reduce lifespan and speed up brain aging and neurodegeneration. Here we examined the effects of clock disruptions on locomotor aging and longevity in Drosophila. We found that lifespan was similarly reduced in three arrhythmic mutants (ClkAR, cyc0 and tim0 and in wild-type flies under constant light, which stops the clock. In contrast, ClkAR mutants showed significantly faster age-related locomotor deficits (as monitored by startle-induced climbing than cyc0 and tim0, or than control flies under constant light. Reactive oxygen species accumulated more with age in ClkAR mutant brains, but this did not appear to contribute to the accelerated locomotor decline of the mutant. Clk, but not Cyc, inactivation by RNA interference in the pigment-dispersing factor (PDF-expressing central pacemaker neurons led to similar loss of climbing performance as ClkAR. Conversely, restoring Clk function in these cells was sufficient to rescue the ClkAR locomotor phenotype, independently of behavioral rhythmicity. Accelerated locomotor decline of the ClkAR mutant required expression of the PDF receptor and correlated to an apparent loss of dopaminergic neurons in the posterior protocerebral lateral 1 (PPL1 clusters. This neuronal loss was rescued when the ClkAR mutation was placed in an apoptosis-deficient background. Impairing dopamine synthesis in a single pair of PPL1 neurons that innervate the mushroom bodies accelerated locomotor decline in otherwise wild-type flies. Our results therefore reveal a novel circadian-independent requirement for Clk in brain circadian neurons to maintain a subset of dopaminergic cells and avoid premature locomotor aging in Drosophila.

  13. Drosophila Clock Is Required in Brain Pacemaker Neurons to Prevent Premature Locomotor Aging Independently of Its Circadian Function

    Science.gov (United States)

    Issa, Abdul-Raouf; Seugnet, Laurent; Klarsfeld, André

    2017-01-01

    Circadian clocks control many self-sustained rhythms in physiology and behavior with approximately 24-hour periodicity. In many organisms, oxidative stress and aging negatively impact the circadian system and sleep. Conversely, loss of the clock decreases resistance to oxidative stress, and may reduce lifespan and speed up brain aging and neurodegeneration. Here we examined the effects of clock disruptions on locomotor aging and longevity in Drosophila. We found that lifespan was similarly reduced in three arrhythmic mutants (ClkAR, cyc0 and tim0) and in wild-type flies under constant light, which stops the clock. In contrast, ClkAR mutants showed significantly faster age-related locomotor deficits (as monitored by startle-induced climbing) than cyc0 and tim0, or than control flies under constant light. Reactive oxygen species accumulated more with age in ClkAR mutant brains, but this did not appear to contribute to the accelerated locomotor decline of the mutant. Clk, but not Cyc, inactivation by RNA interference in the pigment-dispersing factor (PDF)-expressing central pacemaker neurons led to similar loss of climbing performance as ClkAR. Conversely, restoring Clk function in these cells was sufficient to rescue the ClkAR locomotor phenotype, independently of behavioral rhythmicity. Accelerated locomotor decline of the ClkAR mutant required expression of the PDF receptor and correlated to an apparent loss of dopaminergic neurons in the posterior protocerebral lateral 1 (PPL1) clusters. This neuronal loss was rescued when the ClkAR mutation was placed in an apoptosis-deficient background. Impairing dopamine synthesis in a single pair of PPL1 neurons that innervate the mushroom bodies accelerated locomotor decline in otherwise wild-type flies. Our results therefore reveal a novel circadian-independent requirement for Clk in brain circadian neurons to maintain a subset of dopaminergic cells and avoid premature locomotor aging in Drosophila. PMID:28072817

  14. Generation of cardiac pacemaker cells by programming and differentiation.

    Science.gov (United States)

    Husse, Britta; Franz, Wolfgang-Michael

    2016-07-01

    A number of diseases are caused by faulty function of the cardiac pacemaker and described as "sick sinus syndrome". The medical treatment of sick sinus syndrome with electrical pacemaker implants in the diseased heart includes risks. These problems may be overcome via "biological pacemaker" derived from different adult cardiac cells or pluripotent stem cells. The generation of cardiac pacemaker cells requires the understanding of the pacing automaticity. Two characteristic phenomena the "membrane-clock" and the "Ca(2+)-clock" are responsible for the modulation of the pacemaker activity. Processes in the "membrane-clock" generating the spontaneous pacemaker firing are based on the voltage-sensitive membrane ion channel activity starting with slow diastolic depolarization and discharging in the action potential. The influence of the intracellular Ca(2+) modulating the pacemaker activity is characterized by the "Ca(2+)-clock". The generation of pacemaker cells started with the reprogramming of adult cardiac cells by targeted induction of one pacemaker function like HCN1-4 overexpression and enclosed in an activation of single pacemaker specific transcription factors. Reprogramming of adult cardiac cells with the transcription factor Tbx18 created cardiac cells with characteristic features of cardiac pacemaker cells. Another key transcription factor is Tbx3 specifically expressed in the cardiac conduction system including the sinoatrial node and sufficient for the induction of the cardiac pacemaker gene program. For a successful cell therapeutic practice, the generated cells should have all regulating mechanisms of cardiac pacemaker cells. Otherwise, the generated pacemaker cells serve only as investigating model for the fundamental research or as drug testing model for new antiarrhythmics. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

  15. Pacemakers and implantable cardioverter defibrillators - general and anesthetic considerations

    Directory of Open Access Journals (Sweden)

    Amy G. Rapsang

    2014-06-01

    Full Text Available A pacemaking system consists of an impulse generator and lead or leads to carry the electrical impulse to the patient's heart. Pacemaker and implantable cardioverter defibrillator codes were made to describe the type of pacemaker or implantable cardioverter defibrillator implanted. Indications for pacing and implantable cardioverter defibrillator implantation were given by the American College of Cardiologists. Certain pacemakers have magnet-operated reed switches incorporated; however, magnet application can have serious adverse effects; hence, devices should be considered programmable unless known otherwise. When a device patient undergoes any procedure (with or without anesthesia, special precautions have to be observed including a focused history/physical examination, interrogation of pacemaker before and after the procedure, emergency drugs/temporary pacing and defibrillation, reprogramming of pacemaker and disabling certain pacemaker functions if required, monitoring of electrolyte and metabolic disturbance and avoiding certain drugs and equipments that can interfere with pacemaker function. If unanticipated device interactions are found, consider discontinuation of the procedure until the source of interference can be eliminated or managed and all corrective measures should be taken to ensure proper pacemaker function should be done. Post procedure, the cardiac rate and rhythm should be monitored continuously and emergency drugs and equipments should be kept ready and consultation with a cardiologist or a pacemaker-implantable cardioverter defibrillator service may be necessary.

  16. Nerves projecting from the intrinsic cardiac ganglia of the pulmonary veins modulate sinoatrial node pacemaker function

    Science.gov (United States)

    Zarzoso, Manuel; Rysevaite, Kristina; Milstein, Michelle L.; Calvo, Conrado J.; Kean, Adam C.; Atienza, Felipe; Pauza, Dainius H.; Jalife, José; Noujaim, Sami F.

    2013-01-01

    Aims Pulmonary vein ganglia (PVG) are targets for atrial fibrillation ablation. However, the functional relevance of PVG to the normal heart rhythm remains unclear. Our aim was to investigate whether PVG can modulate sinoatrial node (SAN) function. Methods and results Forty-nine C57BL and seven Connexin40+/EGFP mice were studied. We used tyrosine-hydroxylase (TH) and choline-acetyltransferase immunofluorescence labelling to characterize adrenergic and cholinergic neural elements. PVG projected postganglionic nerves to the SAN, which entered the SAN as an extensive, mesh-like neural network. PVG neurones were adrenergic, cholinergic, and biphenotypic. Histochemical characterization of two human embryonic hearts showed similarities between mouse and human neuroanatomy: direct neural communications between PVG and SAN. In Langendorff perfused mouse hearts, PVG were stimulated using 200–2000 ms trains of pulses (300 μs, 400 µA, 200 Hz). PVG stimulation caused an initial heart rate (HR) slowing (36 ± 9%) followed by acceleration. PVG stimulation in the presence of propranolol caused HR slowing (43 ± 13%) that was sustained over 20 beats. PVG stimulation with atropine progressively increased HR. Time-course effects were enhanced with 1000 and 2000 ms trains (P < 0.05 vs. 200 ms). In optical mapping, PVG stimulation shifted the origin of SAN discharges. In five paroxysmal AF patients undergoing pulmonary vein ablation, application of radiofrequency energy to the PVG area during sinus rhythm produced a decrease in HR similar to that observed in isolated mouse hearts. Conclusion PVG have functional and anatomical biphenotypic characteristics. They can have significant effects on the electrophysiological control of the SAN. PMID:23559611

  17. Flexibility.

    Science.gov (United States)

    Humphrey, L. Dennis

    1981-01-01

    Flexibility is an important aspect of all sports and recreational activities. Flexibility can be developed and maintained by stretching exercises. Exercises designed to develop flexibility in ankle joints, knees, hips, and the lower back are presented. (JN)

  18. What Is a Pacemaker?

    Science.gov (United States)

    ... it work? •A pacemaker uses batteries to send electric signals to your heart to help it pump the right way. • The pacemaker is connected to your heart by one or more wires. Tiny electric charges that you can’t feel move through ...

  19. Beneficial effects of losartan for prevention of paroxysmal atrial fibrillation in patients with sick sinus syndrome: analysis with memory function of pacemaker.

    Science.gov (United States)

    Takii, Eiichi; Inage, Tomohito; Yoshida, Teruhisa; Ohe, Masatsugu; Gondo, Takeki; Haraguchi, Go; Ito, Shogo; Kumanomido, Jun; Imaizumi, Tsutomu; Fukuomoto, Yoshihiro

    2016-03-01

    Renin-angiotensin system (RAS) inhibitors may be useful in preventing the occurrence of paroxysmal atrial fibrillation (PAF). However, evaluation of such effect is difficult because many PAF episodes are asymptomatic and not all episodes are detected by intermittent electrocardiographic monitoring. A pacemaker has been developed with dedicated functions for AF detection and electrocardiogram storage. Accordingly, we examined the effect of losartan, an angiotensin receptor blocker on PAF occurrence using this new modality. We enrolled 70 consecutive patients who had undergone dual-chamber pacemaker implantation for sick sinus syndrome. Finally, 62 patients participated in the study. Thirty patients were randomized to the losartan group (mean 43 ± 12 mg/day) and 32 patients to the control group. They were followed up for 3 months. The frequency, the maximum duration and the total duration of PAF recorded by the stored electrocardiograms for the last 1 month during the observation period and study period were compared between the two groups. The change in the frequency of PAF from the observation period in the losartan and control groups was similar (-35 ± 25 vs. -67 ± 62 times; NS). However, the change in the maximum duration and the total duration of PAF was significantly shorter in the losartan group than in the control group (-493 ± 158 vs. -10 ± 69 min; p sick sinus syndrome without hemodynamic changes. This is the first study to show the effect of a renin-angiotensin system inhibitor on the secondary prevention of PAF using the dedicated functions of a pacemaker for PAF detection and electrocardiogram storage.

  20. Abnormal musical pacemaker in a patient with musical hallucinations.

    Science.gov (United States)

    Biran, I; Steiner, I

    2006-12-01

    Music creation requires a highly orchestrated temporal pattern. The study of a patient with repetitive musical hallucinations enabled us to examine temporal pacemakers in music production. Here, we show that the pattern of faster silent production of a chosen tune compared with its production aloud was reversed when the patient produced the hallucinatory tune. This observation might suggest the utilization of a pacemaker(s), which functions differentially during the disease.

  1. [Analysis of pacemaker ECGs].

    Science.gov (United States)

    Israel, Carsten W; Ekosso-Ejangue, Lucy; Sheta, Mohamed-Karim

    2015-09-01

    The key to a successful analysis of a pacemaker electrocardiogram (ECG) is the application of the systematic approach used for any other ECG without a pacemaker: analysis of (1) basic rhythm and rate, (2) QRS axis, (3) PQ, QRS and QT intervals, (4) morphology of P waves, QRS, ST segments and T(U) waves and (5) the presence of arrhythmias. If only the most obvious abnormality of a pacemaker ECG is considered, wrong conclusions can easily be drawn. If a systematic approach is skipped it may be overlooked that e.g. atrial pacing is ineffective, the left ventricle is paced instead of the right ventricle, pacing competes with intrinsic conduction or that the atrioventricular (AV) conduction time is programmed too long. Apart from this analysis, a pacemaker ECG which is not clear should be checked for the presence of arrhythmias (e.g. atrial fibrillation, atrial flutter, junctional escape rhythm and endless loop tachycardia), pacemaker malfunction (e.g. atrial or ventricular undersensing or oversensing, atrial or ventricular loss of capture) and activity of specific pacing algorithms, such as automatic mode switching, rate adaptation, AV delay modifying algorithms, reaction to premature ventricular contractions (PVC), safety window pacing, hysteresis and noise mode. A systematic analysis of the pacemaker ECG almost always allows a probable diagnosis of arrhythmias and malfunctions to be made, which can be confirmed by pacemaker control and can often be corrected at the touch of the right button to the patient's benefit.

  2. Functional flexibility good for skills development

    NARCIS (Netherlands)

    Goudswaard, A.

    2004-01-01

    Making optimal use of the employee’s capacity to perform different tasks (‘functional flexibility’) is positively related to skills development and involvement in decision-making. It may lead to emotional exhaustion, however, if an imbalance exists, such as high job demands combined with a lack of

  3. A flexible sigmoid function of determinate growth

    NARCIS (Netherlands)

    Yin, X.; Goudriaan, J.; Lantinga, E.A.; Vos, J.; Spiertz, J.H.J.

    2003-01-01

    A new empirical equation for the sigmoid pattern of determinate growth, 'the beta growth function', is presented. It calculates weight (w) in dependence of time, using the following three parameters: t(m), the time at which the maximum growth rate is obtained; t(e), the time at the end of growth; an

  4. Functional flexibility good for skills development

    NARCIS (Netherlands)

    Goudswaard, A.

    2004-01-01

    Making optimal use of the employee’s capacity to perform different tasks (‘functional flexibility’) is positively related to skills development and involvement in decision-making. It may lead to emotional exhaustion, however, if an imbalance exists, such as high job demands combined with a lack of a

  5. Dynamic interactions of an intracellular Ca2+ clock and membrane ion channel clock underlie robust initiation and regulation of cardiac pacemaker function.

    Science.gov (United States)

    Maltsev, Victor A; Lakatta, Edward G

    2008-01-15

    For almost half a century it has been thought that the initiation of each heartbeat is driven by surface membrane voltage-gated ion channels (M clocks) within sinoatrial nodal cells. It has also been assumed that pacemaker cell automaticity is initiated at the maximum diastolic potential (MDP). Recent experimental evidence based on confocal cell imaging and supported by numerical modelling, however, shows that initiation of cardiac impulse is a more complex phenomenon and involves yet another clock that resides under the sarcolemma. This clock is the sarcoplasmic reticulum (SR): it generates spontaneous, but precisely timed, rhythmic, submembrane, local Ca(2+) releases (LCR) that appear not at the MDP but during the late, diastolic depolarization (DD). The Ca(2+) clock and M clock dynamically interact, defining a novel paradigm of robust cardiac pacemaker function and regulation. Rhythmic LCRs during the late DD activate inward Na(+)/Ca(2+) exchanger currents and ignite action potentials, which in turn induceCa(2+) transients and SR depletions, resetting the Ca(2+) clock. Both basal and reserve protein kinaseA-dependent phosphorylation of Ca(2+) cycling proteins control the speed and amplitude of SR Ca(2+) cycling to regulate the beating rate by strongly coupled Ca(2+) and M clocks.

  6. Flexible band versus rigid ring annuloplasty for functional tricuspid regurgitation

    Directory of Open Access Journals (Sweden)

    Kanji Kawachi

    2010-09-01

    Full Text Available We review and compare our experience with tricuspid ring annuloplasty between usage of the Cosgrove-Edwards flexible band and the MC3 rigid ring for repair of functional tricuspid regurgitation to determine the efficacy and mid-term durability of tricuspid annuloplasty. 117 patients with functional tricuspid regurgitation undergoing open heart surgery and tricuspid valve repair from May 2005 to December 2007 were reviewed. The flexible bands were used in thirty five patients before October 2006. Since then, the rigid rings were used in the next consecutive eighty two cases. Echocardiographic evaluation of tricuspid regurgitation was performed preoperatively and postoperatively in follow-up schedule. The degree of tricuspid regurgitation was reduced from 2.80±0.67 to 0.71±1.0 (regurgitation severity grade: 0 to 4 in the patients with flexible bands at discharge. It was from 2.68±0.70 to 0.22±0.60 in the patients with rigid rings. At thirty six months postoperative period, tricuspid regurgitation grades in patients with flexible bands and rigid rings were 0.80±0.95 and 0.36±0.77, respectively. Freedom from recurrent tricuspid regurgitation (grade 2 or 3 in patients with flexible bands and rigid rings were 68.6% and 87.8%, respectively. Recurrent tricuspid regurgitation was significantly lower in the patients with rigid rings. Although both flexible band and rigid ring annuloplasty provide low rate of recurrent tricuspid regurgitation, rigid ring annuloplasty might be more effective than flexible band annuloplasty for decreasing functional tricuspid regurgitation in immediate and mid-term postoperative periods.

  7. Modern pacemaker therapy

    Directory of Open Access Journals (Sweden)

    Mijatov Milan

    2010-01-01

    Full Text Available Introduction. Pacemakers are devices that modern medicine and cardiology cannot be imagined without. The technique of implantation comes to surgical procedure where all principles of asepsis and antisepsis have to be respected. Although some complications do happen, they are rather rare. Results. After the implantation of the device, the patient is not handicapped (unless the heart was additionally damaged. On the contrary, the patient returns to his work and functions normally within his family in most of the cases. The first medical appointment is scheduled a month after the implantation and the following are three and six months after. Types of devices. Today there are „new types of electrostimulation”- implantable cardioverter defibrillators and multisite electrostimulators. The former is implanted in patients at high risk of sudden cardiac death and the latter in patients with heart failure and left bundle branch block. Owing to these devices, the sudden cardiac death can be prevented successfully and the quality of a patient’s life is improved.

  8. How Does a Pacemaker Work?

    Science.gov (United States)

    ... a battery, a computerized generator, and wires with sensors at their tips. (The sensors are called electrodes.) The battery powers the generator, ... or single-chamber, pacemaker in the upper chest. Types of Pacemaker Programming The two main types of ...

  9. A Formal Verification Methodology for DDD Mode Pacemaker Control Programs

    Directory of Open Access Journals (Sweden)

    Sana Shuja

    2015-01-01

    Full Text Available Pacemakers are safety-critical devices whose faulty behaviors can cause harm or even death. Often these faulty behaviors are caused due to bugs in programs used for digital control of pacemakers. We present a formal verification methodology that can be used to check the correctness of object code programs that implement the safety-critical control functions of DDD mode pacemakers. Our methodology is based on the theory of Well-Founded Equivalence Bisimulation (WEB refinement, where both formal specifications and implementation are treated as transition systems. We develop a simple and general formal specification for DDD mode pacemakers. We also develop correctness proof obligations that can be applied to validate object code programs used for pacemaker control. Using our methodology, we were able to verify a control program with millions of transitions against the simple specification with only 10 transitions. Our method also found several bugs during the verification process.

  10. [What the internist needs to know about pacemakers].

    Science.gov (United States)

    Nüssli, Dominique; Schär, Beat

    2013-08-07

    In Switzerland, in 2011, 4463 patients underwent pacemaker implantation. This review article focusses on basic pacemaker functions, some fundamental remarks on pacemaker therapy and especially indications and pacemaker models. The current guidelines for PM indications date from the years 2007 [1] and 2008 [2] and form the basis of this article. Very rare indications (congenital heart disease, bradycardia after heart transplantation) are not discussed. Each year, new pacemaker models are released that provide advanced diagnostic features (e. g. detailed heart rate memory, 1:1 ECG recordings). However, these features do not significantly change everyday practice. An innovation with clinical impact is the "MRI-safe" system that has been introduced about a year ago.

  11. The cardiac pacemaker patient. Might the pacer be directly irradiated?

    Energy Technology Data Exchange (ETDEWEB)

    Tsekos, A.; Momm, F.; Brunner, M.; Guttenberger, R. [Universitaetsklinikum Freiburg (Germany)

    2000-11-01

    According to recommendations listed in a recent review, pacemakers generally should not be irradiated directly. They should be shielded from ionizing radiation or their position changed. Direct irradiation can cause pacemaker failure. There are no clinical signals to indicate a near failure. When controlling pacemaker function, there is often a change in the magnetic frequency before malfunction occurs. If a malfunction results in a partial heart failure only, there would be enough time to implant another pacemaker. As can be seen from a case described here, a policy of 'wait and see' may be adopted even if there are changes in the magnetic frequency. if there is any danger to the patient's life, the feasibility of using an external pacemaker system may be explored, especially in cases where there is a strong need for radiotherapy (severe pain, infiltration of plexus). Risks and benefits should be carefully weighed and discussed with the patient.

  12. Matrix Transfer Function Design for Flexible Structures: An Application

    Science.gov (United States)

    Brennan, T. J.; Compito, A. V.; Doran, A. L.; Gustafson, C. L.; Wong, C. L.

    1985-01-01

    The application of matrix transfer function design techniques to the problem of disturbance rejection on a flexible space structure is demonstrated. The design approach is based on parameterizing a class of stabilizing compensators for the plant and formulating the design specifications as a constrained minimization problem in terms of these parameters. The solution yields a matrix transfer function representation of the compensator. A state space realization of the compensator is constructed to investigate performance and stability on the nominal and perturbed models. The application is made to the ACOSSA (Active Control of Space Structures) optical structure.

  13. Atrioventricular Pacemaker Lead Reversal

    Directory of Open Access Journals (Sweden)

    Mehmet K Aktas, MD

    2007-01-01

    Full Text Available During cardiac surgery temporary epicardial atrial and ventricular leads are placed in case cardiac pacing is required postoperatively. We present the first reported series of patients with reversal of atrioventricular electrodes in the temporary pacemaker without any consequent deleterious hemodynamic effect. We review the electrocardiographic findings and discuss the findings that lead to the discovery of atrioventricular lead reversal.

  14. Flexible, wearable, and functional graphene-textile composites

    Science.gov (United States)

    Liu, Ying; Zhang, Kun-Ning; Zhang, Ying; Tao, Lu-Qi; Li, Yu-Xing; Wang, Dan-Yang; Yang, Yi; Ren, Tian-Ling

    2017-06-01

    In this paper, a flexible, wearable, and functional graphene-textile composite is demonstrated. Laser scribing technology is applied to fabricate a graphene film. The thin layer of polydimethylsiloxane is covered on the surface of the graphene-textile film evenly, which would improve the abrasive resistance of the film, enhance the ability to adapt to environmental changes, and extend the service life, while maintaining the device's excellent flexibility and comfort. The graphene-textile composite can achieve constant temperature heating by controlling the input voltage, detect the human movement, and perceive the human pulse signal. The composite presents great commercial prospects and a large value in the medical, daily wear, and other areas that are closely related to human lives.

  15. Increasing fisheries management options with a flexible cost function

    DEFF Research Database (Denmark)

    Marchal, P.; Horwood, J.

    1998-01-01

    This study proposes a dynamic control of fisheries by fishing effort, calculated so as to optimize a novel cost function, over a long period of management, based upon an example of the exploitation of the Celtic Sea cod. This cost function is a flexible weighed compromise between: (i) minimizing......) is zero, the optimization of the cost function usually results in a non- linear divergent control, which is an artefact related to the choice of the length of the management period. (C) 1998 International Council for the Exploration of the Sea....... of fishing effort towards the agreed long-term target, a decrease in short-term yields, and an increase in long-term yields. When the weight attached to (iii) is non-zero, the optimization of the cost function provides a non-oscillatory, convergent, and near-linear control. When the weight attached to (iii...

  16. Large deflection of flexible tapered functionally graded beam

    Institute of Scientific and Technical Information of China (English)

    A.R.Davoodinik; G.H.Rahimi

    2011-01-01

    In this paper the semi-analytical analyses of the flexible cantilever tapered functionally graded beam under combined inclined end loading and intermediate loading are studied.In order to derive the fully non-linear equations governing the non-linear deformation,a curvilinear coordinate system is introduced.A general non-linear second order differential equation that governs the shape of a deflected beam is derived based on the geometric nonlinearities,infinitesimal local displacements and local rotation concepts with remarkable physical properties of functionally graded materials.The solutions obtained from semi-analytical methods are numerically compared with the existing elliptic integral solution for the case of a flexible uniform cantilever functionally graded beam.The effects of taper ratio,inclined end load angle and material property gradient on large deflection of the beam are evaluated.The Adomian decomposition method will be useful toward the design of tapered functionally graded compliant mechanisms driven by smart actuators.

  17. Flexible Lyapunov Functions and Applications to Fast Mechatronic Systems

    Directory of Open Access Journals (Sweden)

    Mircea Lazar

    2010-03-01

    Full Text Available The property that every control system should posses is stability, which translates into safety in real-life applications. A central tool in systems theory for synthesizing control laws that achieve stability are control Lyapunov functions (CLFs. Classically, a CLF enforces that the resulting closed-loop state trajectory is contained within a cone with a fixed, predefined shape, and which is centered at and converges to a desired converging point. However, such a requirement often proves to be overconservative, which is why most of the real-time controllers do not have a stability guarantee. Recently, a novel idea that improves the design of CLFs in terms of flexibility was proposed. The focus of this new approach is on the design of optimization problems that allow certain parameters that define a cone associated with a standard CLF to be decision variables. In this way non-monotonicity of the CLF is explicitly linked with a decision variable that can be optimized on-line. Conservativeness is significantly reduced compared to classical CLFs, which makes flexible CLFs more suitable for stabilization of constrained discrete-time nonlinear systems and real-time control. The purpose of this overview is to highlight the potential of flexible CLFs for real-time control of fast mechatronic systems, with sampling periods below one millisecond, which are widely employed in aerospace and automotive applications.

  18. What Are the Risks of Pacemaker Surgery?

    Science.gov (United States)

    ... NHLBI on Twitter. What Are the Risks of Pacemaker Surgery? Pacemaker surgery generally is safe. If problems do occur, ... bruising, or infection in the area where the pacemaker was placed Blood vessel or nerve damage A ...

  19. MRI-conditional pacemakers: current perspectives

    Directory of Open Access Journals (Sweden)

    Ferreira AM

    2014-05-01

    Full Text Available António M Ferreira,1,2 Francisco Costa,2 António Tralhão,2 Hugo Marques,3 Nuno Cardim,1 Pedro Adragão1,2 1Cardiology Department, Hospital da Luz, 2Cardiology Department, Hospital Santa Cruz- CHLO, 3Radiology Department, Hospital da Luz, Lisbon, Portugal Abstract: Use of both magnetic resonance imaging (MRI and pacing devices has undergone remarkable growth in recent years, and it is estimated that the majority of patients with pacemakers will need an MRI during their lifetime. These investigations will generally be denied due to the potentially dangerous interactions between cardiac devices and the magnetic fields and radiofrequency energy used in MRI. Despite the increasing reports of uneventful scanning in selected patients with conventional pacemakers under close surveillance, MRI is still contraindicated in those circumstances and cannot be considered a routine procedure. These limitations prompted a series of modifications in generator and lead engineering, designed to minimize interactions that could compromise device function and patient safety. The resulting MRI-conditional pacemakers were first introduced in 2008 and the clinical experience gathered so far supports their safety in the MRI environment if certain conditions are fulfilled. With this technology, new questions and controversies arise regarding patient selection, clinical impact, and cost-effectiveness. In this review, we discuss the potential risks of MRI in patients with electronic cardiac devices and present updated information regarding the features of MRI-conditional pacemakers and the clinical experience with currently available models. Finally, we provide some guidance on how to scan patients who have these devices and discuss future directions in the field. Keywords: pacemakers, magnetic resonance imaging, MRI, MRI-conditional devices, safety

  20. Pacemaker Use Following Heart Transplantation.

    Science.gov (United States)

    Mallidi, Hari R; Bates, Michael

    2017-01-01

    The incidence of permanent pacemaker implantation after orthotopic heart transplantation has been reported to be 2%-24%. Transplanted hearts usually exhibit sinus rhythm in the operating room following reperfusion, and most patients do not exhibit significant arrhythmias during the postoperative period. However, among the patients who do exhibit abnormalities, pacemakers may be implanted for early sinus node dysfunction but are rarely used after 6 months. Permanent pacing is often required for atrioventricular block. A different cohort of transplant patients presents later with bradycardia requiring pacemaker implantation, reported to occur in approximately 1.5% of patients. The objectives of this study were to investigate the indications for pacemaker implantation, compare the need for pacemakers following bicaval vs biatrial anastomosis, and examine the long-term outcomes of heart transplant patients who received pacemakers. For this retrospective, case-cohort, single-institution study, patients were identified from clinical research and administrative transplant databases. Information was supplemented with review of the medical records. Standard statistical techniques were used, with chi-square testing for categorical variables and the 2-tailed t test for continuous variables. Survival was compared with the use of log-rank methods. Between January 1968 and February 2008, 1,450 heart transplants were performed at Stanford University. Eighty-four patients (5.8%) were identified as having had a pacemaker implanted. Of these patients, 65.5% (55) had the device implanted within 30 days of transplantation, and 34.5% (29) had late implantation. The mean survival of patients who had an early pacemaker implant was 6.4 years compared to 7.7 years for those with a late pacemaker implant (Ppacemaker implantation. Starting in 1997, a bicaval technique was used for implantation. The incidence of pacemaker implantation by technique was 2.0% for bicaval and 9.1% for biatrial (P

  1. Pacemaker Use Following Heart Transplantation

    Science.gov (United States)

    Mallidi, Hari R.; Bates, Michael

    2017-01-01

    Background: The incidence of permanent pacemaker implantation after orthotopic heart transplantation has been reported to be 2%-24%. Transplanted hearts usually exhibit sinus rhythm in the operating room following reperfusion, and most patients do not exhibit significant arrhythmias during the postoperative period. However, among the patients who do exhibit abnormalities, pacemakers may be implanted for early sinus node dysfunction but are rarely used after 6 months. Permanent pacing is often required for atrioventricular block. A different cohort of transplant patients presents later with bradycardia requiring pacemaker implantation, reported to occur in approximately 1.5% of patients. The objectives of this study were to investigate the indications for pacemaker implantation, compare the need for pacemakers following bicaval vs biatrial anastomosis, and examine the long-term outcomes of heart transplant patients who received pacemakers. Methods: For this retrospective, case-cohort, single-institution study, patients were identified from clinical research and administrative transplant databases. Information was supplemented with review of the medical records. Standard statistical techniques were used, with chi-square testing for categorical variables and the 2-tailed t test for continuous variables. Survival was compared with the use of log-rank methods. Results: Between January 1968 and February 2008, 1,450 heart transplants were performed at Stanford University. Eighty-four patients (5.8%) were identified as having had a pacemaker implanted. Of these patients, 65.5% (55) had the device implanted within 30 days of transplantation, and 34.5% (29) had late implantation. The mean survival of patients who had an early pacemaker implant was 6.4 years compared to 7.7 years for those with a late pacemaker implant (Ptransplantation had a pretransplant diagnosis of ischemic cardiomyopathy. In our cohort, the need for a permanent pacemaker was also associated with older

  2. Comparative effects of extremely high power microwave pulses and a brief CW irradiation on pacemaker function in isolated frog heart slices.

    Science.gov (United States)

    Pakhomov, A G; Mathur, S P; Doyle, J; Stuck, B E; Kiel, J L; Murphy, M R

    2000-05-01

    The existence of specific bioeffects due to high peak power microwaves and their potential health hazards are among the most debated but least explored problems in microwave biology. The present study attempted to reveal such effects by comparing the bioeffects of short trains of extremely high power microwave pulses (EHPP, 1 micros width, 250-350 kW/g, 9.2 GHz) with those of relatively low power pulses (LPP, 0.5-10 s width, 3-30 W/g, 9.2 GHz). EHPP train duration and average power were made equal to those of an LPP; therefore both exposure modalities produced the same temperature rise. Bioeffects were studied in isolated, spontaneously beating slices of the frog heart. In most cases, a single EHPP train or LPP immediately decreased the inter-beat interval (IBI). The effect was proportional to microwave heating, fully reversible, and easily reproducible. The magnitude and time course of EHPP- and LPP-induced changes always were the same. No delayed or irreversible effects of irradiation were observed. The same effect could be repeated in a single preparation numerous times with no signs of adaptation, sensitization, lasting functional alteration, or damage. A qualitatively different effect, namely, a temporary arrest of preparation beats, could be observed when microwave heating exceeded physiologically tolerable limits. This effect also did not depend on whether the critical temperature rise was produced by LPP or EHPP exposure. Within the studied limits, we found no indications of EHPP-specific bioeffects. EHPP- and LPP-induced changes in the pacemaker rhythm of isolated frog heart preparation were identical and could be entirely attributed to microwave heating.

  3. Tuning the flexibility in MOFs by SBU functionalization.

    Science.gov (United States)

    Bon, Volodymyr; Kavoosi, Negar; Senkovska, Irena; Müller, Philipp; Schaber, Jana; Wallacher, Dirk; Többens, Daniel M; Mueller, Uwe; Kaskel, Stefan

    2016-03-14

    A new approach for the fine tuning of flexibility in MOFs, involving functionalization of the secondary building unit, is presented. The "gate pressure" MOF [Zn3(bpydc)2(HCOO)2] was used as a model material and SBU functionalization was performed by using monocarboxylic acids such as acetic, benzoic or cinnamic acids instead of formic acid in the synthesis. The resulting materials are isomorphous to [Zn3(bpydc)2(HCOO)2] in the "as made" form, but show different structural dynamics during the guest removal. The activated materials have entirely different properties in the nitrogen physisorption experiments clearly showing the tunability of the gate pressure, at which the structural transformation occurs, by using monocarboxylic acids with varying backbone structure in the synthesis. Thus, increasing the number of carbon atoms in the backbone leads to the decreasing gate pressure required to initiate the structural transition. Moreover, in situ adsorption/PXRD data suggest differences in the mechanism of the structural transformations: from "gate opening" in the case of formic acid to "breathing" if benzoic acid is used.

  4. Functional Flexibility in Women's Commitment-Skepticism Bias

    Directory of Open Access Journals (Sweden)

    Christina M. Brown

    2015-04-01

    Full Text Available If a woman overestimates her romantic partner's commitment, the cost to her fitness—reproduction without an investing partner—can be considerable. Error Management Theory predicts that women have an evolved bias to be skeptical of men's commitment in a relationship, which reduces the likelihood of making a costly false positive error. However, because error probabilities are inversely related, this commitment-skepticism bias simultaneously increases the likelihood of missed opportunities, or false negatives. False positives when gauging a partner's commitment are the more costly error for women, but missing an opportunity to secure a genuinely high-quality mate can also be quite costly. We predicted and found that women's mating cognitions are functionally flexible, such that women do not exhibit the commitment-skepticism bias when faced with behavioral evidence that a male partner is willing to commit (Study 1. This suggests that relationship-enhancing behaviors are one contextual cue that may lessen the bias. However, not all relationship-enhancing behaviors are equally diagnostic of a person's true commitment intent. When comparing men and women's commitment thresholds, we found that women require more behavioral evidence than men do to feel certain of their partner's commitment to them (Study 2.

  5. Flexible Lyapunov Functions and Applications to Fast Mechatronic Systems

    CERN Document Server

    Lazar, M

    2010-01-01

    The property that every control system should posses is stability, which translates into safety in real-life applications. A central tool in systems theory for synthesizing control laws that achieve stability are control Lyapunov functions (CLFs). Classically, a CLF enforces that the resulting closed-loop state trajectory is contained within a cone with a fixed, predefined shape, and which is centered at and converges to a desired converging point. However, such a requirement often proves to be overconservative, which is why most of the real-time controllers do not have a stability guarantee. Recently, a novel idea that improves the design of CLFs in terms of flexibility was proposed. The focus of this new approach is on the design of optimization problems that allow certain parameters that define a cone associated with a standard CLF to be decision variables. In this way non-monotonicity of the CLF is explicitly linked with a decision variable that can be optimized on-line. Conservativeness is significantly ...

  6. Flexibility Training and Functional Ability in Older Adults: A Systematic Review

    OpenAIRE

    Liza Stathokostas; Little, Robert M. D.; A. A. Vandervoort; Paterson, Donald H.

    2012-01-01

    Background. As indicated in a recent systematic review relating to Canada’s Physical Activity Guidelines for Older Adults, exercise interventions in older adults can maintain or improve functional abilities. Less is known about the role of flexibility in the maintenance or improvement of functional abilities, and there currently does not exist a synthesis of the literature supporting a consensus on flexibility training prescription. Purpose. To systematically review the effects of flexibility...

  7. Interference of cardiac pacemaker and implantable cardioverter-defibrillator activity during electronic dental device use.

    Science.gov (United States)

    Roedig, Jason J; Shah, Jignesh; Elayi, Claude Samy; Miller, Craig S

    2010-05-01

    The authors conducted a study to determine if electromagnetic interference of cardiac pacemaker and implantable cardioverter-defibrillator (ICD) activity occurs during the operation of electronic dental devices. The authors tested nine electronic dental devices in vitro to assess their ability to interfere with the function of two pacemakers and two ICDs as determined by electrocardiographic telemetry. The pacing activity of both pacemakers and the dual-chamber ICD were inhibited during operation of the battery-operated composite curing light at between 2 and 10 centimeters from the generator or leads. The use of the ultrasonic scaler interfered with the pacing activity of the dual-chamber pacemaker at between 17 and 23 cm from the generator or leads, the single-chamber pacemaker at 15 cm from the generator or leads and both ICDs at 7 cm from the leads. The operation of the ultrasonic cleaning system interfered with the activity of the dual-chamber pacemaker at between 15 and 23 cm from the generator or leads, and of the single-chamber pacemaker at 12 cm. Operation of the electric toothbrush, electrosurgical unit, electric pulp tester, high- and low-speed handpieces, and an amalgamator did not alter pacing function. Select electronic dental devices interfere with pacemakers' and ICDs' sensing and pacing activity in vitro. Use of the ultrasonic scaler, ultrasonic cleaning system and battery-operated composite curing light may produce deleterious effects in patients who have pacemakers or ICDs.

  8. Flexibility training and functional ability in older adults: a systematic review.

    Science.gov (United States)

    Stathokostas, Liza; Little, Robert M D; Vandervoort, A A; Paterson, Donald H

    2012-01-01

    Background. As indicated in a recent systematic review relating to Canada's Physical Activity Guidelines for Older Adults, exercise interventions in older adults can maintain or improve functional abilities. Less is known about the role of flexibility in the maintenance or improvement of functional abilities, and there currently does not exist a synthesis of the literature supporting a consensus on flexibility training prescription. Purpose. To systematically review the effects of flexibility-specific training interventions on measures of functional outcomes in healthy older adults over the age of 65 years. Methods. Five electronic databases were searched for intervention studies involving concepts related to aging, flexibility, functional outcomes, and training interventions. After evaluating the articles for relevance, 22 studies were considered. Results. The results suggested that while flexibility-specific interventions may have effects on range of motion (ROM) outcomes, there is conflicting information regarding both the relationship between flexibility interventions and functional outcomes or daily functioning. Conclusions. Due to the wide range of intervention protocols, body parts studied, and functional measurements, conclusive recommendations regarding flexibility training for older adults or the validity of flexibility training interventions as supplements to other forms of exercise, or as significant positive influences on functional ability, require further investigation.

  9. Effect of Alcohol on Pacemaking and Driving Function of Sinoatrail Node in Heart of Mammals%乙醇对哺乳动物心脏窦房结搏动信号传导功能的影响

    Institute of Scientific and Technical Information of China (English)

    程睿; 张季谦; 李翔; 高飞

    2013-01-01

    利用哺乳动物心脏窦房结组织的二维解剖模型,模拟乙醇对窦房结搏动及信号传导功能的影响.结果发现,一方面摄入过量的乙醇会使得有生理缺陷的心脏体系出现异常搏动现象,这与临床实验现象相吻合.另一方面发现,摄入乙醇对于窦房结搏动功能有三类影响:降低L型钙离子通道的导电性能;减小神经系统分泌乙酰胆碱的能力;若过量摄入乙醇,则降低钠离子通道的导电性能.这三种情况都将直接影响窦房结组织的正常搏动功能.模拟结果有助于进一步理解因摄入乙醇而引发心脏体系异常搏动的内在机理,并为临床诊断和预防提供一定的理论参考.%By using a 2D anatomical model of the intake SA node and surrounding atrial muscle of the rabbit heart,which is proposed by Zhang et al,the effect of the alcohol on pacemaking and driving function of sinoatrail node is investigated by computer simulation.The results show,on one hand,excessive intake of the alcohol can reproduce the phenomenon of abnormal rhythm in heart with physiological defect,which are consistent with the clinical phenomena,such as abnormal pacemaking or even sudden cardiac death,which is induced by reduction of the ethanol irrigation stomach experiment on rabbit.On the other hand,using this model can simulate the influence of SA node which has the ethanol intake,and the influences perform in three aspects:reduce the electric conductivity of L calcium ion channels; reduce the ability to secrete acetylcholine of the nervous system; in excess intake of ethanol,reduce the electric conductivity of sodium channel.These three factors directly affect the pacemaking and driving function of sinoatrail node.These results will help to reveal the internal mechanism of the abnormal pacemaking in complex cardiac system absorbing the ethanol and provide a theoretical guidance for the clinical diagnosis of angiocardiopathy.

  10. Learning and cognitive flexibility: frontostriatal function and monoaminergic modulation.

    Science.gov (United States)

    Kehagia, Angie A; Murray, Graham K; Robbins, Trevor W

    2010-04-01

    Learning in a constant environment, and adapting flexibly to a changing one, through changes in reinforcement contingencies or valence-free cues, depends on overlapping circuitry that interconnects the prefrontal cortex (PFC) with the striatum and is subject to several forms of neurochemical modulation. We present evidence from recent studies in animals employing electrophysiological, pharmacological and lesion techniques, and neuroimaging, neuropsychological and pharmacological investigations of healthy humans and clinical patients. Dopamine (DA) neurotransmission in the medial striatum and PFC is critical for basic reinforcement learning and the integration of negative feedback during reversal learning, whilst orbitofrontal 5-hydroxytryptamine (5-HT) likely mediates this type of low level flexibility, perhaps by reducing interference from salient stimuli. The role of prefrontal noradrenaline (NA) in higher order flexibility indexed through attentional set-shifting has recently received significant empirical support, and similar avenues appear promising in the field of task switching.

  11. The dual pathway to creativity model : Creative ideation as a function of flexibility and persistence

    NARCIS (Netherlands)

    Nijstad, B.A.; De Dreu, C.K.W.; Rietzschel, E.F.; Baas, M.

    2010-01-01

    The dual pathway to creativity model argues that creativity-the generation of original and appropriate ideas-is a function of cognitive flexibility and cognitive persistence, and that dispositional or situational variables may influence creativity either through their effects on flexibility, on pers

  12. Wireless power transfer for a pacemaker application.

    Science.gov (United States)

    Vulfin, Vladimir; Sayfan-Altman, Shai; Ianconescu, Reuven

    2017-05-01

    An artificial pacemaker is a small medical device that uses electrical impulses, delivered by electrodes contracting the heart muscles, to regulate the beating of the heart. The pacemaker is implanted under the skin, and uses for many years regular non-rechargeable batteries. However, the demand for rechargeable batteries in pacemakers increased, and the aim of this work is to design an efficient charging system for pacemakers.

  13. Pacemaker-associated Bacillus cereus endocarditis.

    Science.gov (United States)

    Barraud, Olivier; Hidri, Nadia; Ly, Kim; Pichon, Nicolas; Manea, Petrus; Ploy, Marie-Cécile; Garnier, Fabien

    2012-11-01

    We report the case of a pacemaker-associated Bacillus cereus endocarditis in a nonimmunocompromised patient. Antibiotic treatment was ineffective, and the pacemaker had to be removed. B. cereus was cultured from several blood samples and from the pacemaker electrodes. This case underlines the contribution of the rpoB gene for Bacillus species determination.

  14. 21 CFR 870.3700 - Pacemaker programmers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker programmers. 870.3700 Section 870.3700...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3700 Pacemaker programmers. (a) Identification. A pacemaker programmer is a device used to change noninvasively one or more of...

  15. 21 CFR 870.3670 - Pacemaker charger.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker charger. 870.3670 Section 870.3670 Food... DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3670 Pacemaker charger. (a) Identification. A pacemaker charger is a device used transcutaneously to recharge the batteries of a rechargeable...

  16. Subacute Right Ventricle Perforation by Pacemaker Lead Presenting with Left Hemothorax and Shock

    Directory of Open Access Journals (Sweden)

    Julianne Nichols

    2015-01-01

    Full Text Available Cardiac perforation by pacemaker is a rare but potentially fatal complication. Acute perforations occurring within twenty-four hours of insertion of pacemaker can lead to hemopericardium, cardiac tamponade, and death. Hemothorax occurring as an acute complication of pacemaker insertion is reported but extremely rare. Previously, hemothorax and shock as a subacute complication following pacemaker insertion have not been reported. We report the case of an 85-year-old patient who presented with shock from hemothorax caused by pacemaker perforation, two weeks after insertion. Device interrogation showed normal function. Chest X-ray and echocardiogram missed lead dislocation and the diagnosis was made on computed tomogram (CT of the chest. Following surgical repair, a new ventricular pacemaker was placed transvenously in the right ventricular septum. This case illustrates that CT scan of the chest should be performed in all patients in whom cardiac perforation by pacemaker is suspected but not diagnosed on chest X-ray and echocardiogram. Normal functioning of pacemaker on device interrogation does not exclude perforation.

  17. Pacemaking Kisspeptin Neurons

    Science.gov (United States)

    Kelly, Martin J.; Zhang, Chunguang; Qiu, Jian; Rønnekleiv, Oline K.

    2013-01-01

    Kisspeptin (Kiss1) neurons are vital for reproduction. GnRH neurons express the kisspeptin receptor, GPR 54, and kisspeptins potently stimulate the release of GnRH by depolarising and inducing sustained action potential firing in GnRH neurons. As such Kiss1 neurons may be the pre-synaptic pacemaker neurons in the hypothalamic circuitry that controls reproduction. There are at least two different populations of Kiss1 neurons: one in the rostral periventricular area (RP3V) that is stimulated by oestrogens and the other in the arcuate nucleus that is inhibited by oestrogens. How each of these Kiss1 neuronal populations participate in the regulation of the reproductive cycle is currently under intense investigation. Based on electrophysiological studies in the guinea pig and mouse, Kiss1 neurons in general are capable of generating burst firing behavior. Essentially all Kiss1 neurons, which have been studied thus far in the arcuate nucleus, express the ion channels necessary for burst firing, which include hyperpolarization-activated, cyclic nucleotide gated cation (HCN) channels and the T-type calcium (Cav3.1) channels. Under voltage clamp conditions, these channels produce distinct currents that under current clamp conditions can generate burst firing behavior. The future challenge is to identify other key channels and synaptic inputs involved in the regulation of the firing properties of Kiss1 neurons and the physiological regulation of the expression of these channels and receptors by oestrogens and other hormones. The ultimate goal is to understand how Kiss1 neurons control the different phases of GnRH neurosecretion and hence reproduction. PMID:23884368

  18. Effects of irradiation on the components of implantable pacemakers

    CERN Document Server

    Kawamura, S; Kuga, N; Shiba, T; Hirose, T; Fujimoto, H; Toyoshima, T; Hyodo, K; Matoba, M

    2003-01-01

    The purpose of this study was to examine the effects of irradiation on implantable pacemaker components. The pacemaker was divided into three components: lead wire and electrode, battery, and electrical circuit, and each component was irradiated by X-ray and electron beams, respectively. The pacemaker parameters were measured by both telemetry data of the programmer and directly measured data from the output terminal. The following results were obtained. For the lead wire and electrode, there was no effect on the pacemaker function due to irradiation by X-ray and electron beams. In the case of battery irradiation, there was no change in battery voltage or current up to 236 Gy X-ray dose. In the electrical circuit, the pacemaker reverted to the regular beating rate (fixed-rate mode) immediately after the start of X-ray irradiation, and it continued in this mode during irradiation. In patients with their own heartbeat rhythm, changing to the fixed-rate mode may cause dangerous conditions such as ventricular fib...

  19. A novel non invasive measurement of hemodynamic parameters: Comparison of single-chamber ventricular and dual-chamber pacemaker

    Directory of Open Access Journals (Sweden)

    Ingrid M. Pardede

    2008-03-01

    Full Text Available We carried out a cross sectional study to analyze hemodynamic parameters of single-chamber ventricular pacemaker compared with dual-chamber pacemaker by using thoracic electrical bioimpedance monitoring method (Physio Flow™ - a novel simple non-invasive measurement. A total of 48 consecutive outpatients comprised of 27 single chamber pacemaker and 21 dual chamber were analyzed. We measured cardiac parameters: heart rate, stroke volume index, cardiac output index, estimated ejection fraction, end diastolic volume, early diastolic function ratio, thoracic fluid index, and systemic parameters: left cardiac work index and systemic vascular resistance index. Baseline characteristic and pacemaker indication were similar in both groups. Cardiac parameters assessment revealed no significant difference between single-chamber pacemaker and dual-chamber pacemaker in heart rate, stroke volume index, cardiac index, estimated ejection fraction, end-diastolic volume, thoracic fluid index. There was significantly higher early diastolic function ratio in single-chamber pacemaker compared to dual-chamber pacemaker: 92% (10.2-187.7% vs. 100.6% (48.7-403.2%; p=0.006. Systemic parameters assessment revealed significantly higher left cardiac work index in single-chamber group than dual-chamber group 4.9 kg.m/m² (2.8-7.6 kg.m/m² vs. 4.3 kg.m/m² (2.9-7.2 kg.m/m²; p=0.004. There was no significant difference on systemic vascular resistance in single-chamber compared to dual-chamber pacemaker. Single-chamber ventricular pacemaker provides similar stroke volume, cardiac output and left cardiac work, compared to dual-chamber pacemaker. A non-invasive hemodynamic measurement using thoracic electrical bioimpedance is feasible for permanent pacemaker outpatients. (Med J Indones 2008; 17: 25-32Keywords: Permanent pacemaker, single chamber, dual chamber, thoracic electrical bioimpedance, hemodynamic parameter

  20. Design of the Pacemaker REmote Follow-up Evaluation and Review (PREFER trial to assess the clinical value of the remote pacemaker interrogation in the management of pacemaker patients

    Directory of Open Access Journals (Sweden)

    Johnson W Ben

    2008-04-01

    Full Text Available Abstract Background Although pacemakers are primarily used for the treatment of bradycardia, diagnostic data available in current pacemakers allow them to be also used as sophisticated, continuous monitoring devices. Easy access to these stored data may assist clinicians in making diagnostic and therapeutic decisions sooner, thus avoiding potential long-term sequelae due to untreated clinical disorders. Internet-based remote device interrogation systems provide clinicians with frequent and complete access to stored data in pacemakers. In addition to monitoring device function, remote monitors may be a helpful tool in assisting physicians in the management of common arrhythmia disorders. Methods The Pacemaker REmote Follow-up Evaluation and Review (PREFER trial is a prospective, randomized, parallel, unblinded, multicenter, open label clinical trial to determine the utility of remote pacemaker interrogation in the earlier diagnosis of clinically actionable events compared to the existing practice of transtelephonic monitoring. There have been 980 patients enrolled and randomized to receive pacemaker follow up with either remote interrogation using the Medtronic CareLink® Network (CareLink versus the conventional method of transtelephonic monitoring (TTM in addition to periodic in-person interrogation and programming evaluations. The purpose of this manuscript is to describe the design of the PREFER trial. The results, to be presented separately, will characterize the number of clinically actionable events as a result of pacemaker follow-up using remote interrogation instead of TTM. Trial registration ClinicalTrials.gov: NCT00294645.

  1. The Drosophila melanogaster circadian pacemaker circuit

    Indian Academy of Sciences (India)

    Vasu Sheeba

    2008-12-01

    As an experimental model system, the fruit fly Drosophila melanogaster has been seminal in shaping our understanding of the circadian clockwork. The wealth of genetic tools at our disposal over the past four decades has enabled discovery of the genetic and molecular bases of circadian rhythmicity. More recently, detailed investigation leading to the anatomical, neurochemical and electrophysiological characterization of the various neuronal subgroups that comprise the circadian machinery has revealed pathways through which these neurons come together to act as a neuronal circuit. Thus the D. melanogaster circadian pacemaker circuit presents a relatively simple and attractive model for the study of neuronal circuits and their functions.

  2. Pacemaker patients' perception of unsafe activities: a survey

    Directory of Open Access Journals (Sweden)

    Shafquat Azam

    2008-11-01

    Full Text Available Abstract Background Cardiac pacing is a recognized and widely used treatment for patients presenting with bradycardia. Physicians expect patients to return to normal activities almost immediately post implantation. However, patients themselves may perceive interference to pacemaker function by various routine activities and devices, and hence continue to lead restricted, disabled lives. The aim of this study is to determine if routine activities are perceived by pacemaker patients to interfere with their device function. Methods A descriptive cross sectional survey was carried out on consecutive patients at the pacemaker clinic at a public hospital in Karachi, Pakistan. A 47-question tool was developed and tested. Patients' perceptions of safety of performing various routine activities, along with socio-demographic data were recorded. Results The final sample included 93 adult patients (45% males. 41% were illiterate. 77.4% recalled receiving counselling at implantation, predominantly from the implanting physician and house staff. A considerable proportion of patients considered many routine activities unsafe including driving automobiles (28%, passing through metal detectors (31%, bending over (37%, and sleeping on the side of the pacemaker (30%. Also considered unsafe were operation of household appliances- TV/VCR (television/video cassette recorders (53%, irons (55% and electrical wall switches (56%. For nearly all variables neither literacy nor history of counselling improved incorrect perceptions. Conclusion This study shows that our pacemaker patients perceive many routine activities as unsafe, potentially leading to disabling life style modifications. The tremendous investment in pacemaker technology to improve patient performance is not going to pay dividends if patients continue to remain disabled due to incorrect perceptions. Further studies are required to determine the reasons for these misperceptions, and to determine if these

  3. Is the gated blood pool scan useful for optimization of programmable cardiac pacemakers

    Energy Technology Data Exchange (ETDEWEB)

    Gunkel, H.; Otto, H.J.; Pundrich, R.; Mann, D.

    1986-08-01

    The significance of the ECG-triggered cardiac blood pool scan for optimization of physiological parameters of multiprogrammable cardiac pacemakers was investigated. Six patients were investigated, and two case reports are demonstrated in detail. By use of the quantitative evaluation of the parametric scans and other function parameters it is possible to evaluate cardiac function objectively in relation to the stimulation frequency and AV-delay using demand/delay pacemakers. These first results encourage the further use of this technique for evaluation of cardiac function in patients with programmable pacemakers.

  4. [Wide QRS tachycardia preceded by pacemaker spikes].

    Science.gov (United States)

    Romero, M; Aranda, A; Gómez, F J; Jurado, A

    2014-04-01

    The differential diagnosis and therapeutic management of wide QRS tachycardia preceded by pacemaker spike is presented. The pacemaker-mediated tachycardia, tachycardia fibrillo-flutter in patients with pacemakers, and runaway pacemakers, have a similar surface electrocardiogram, but respond to different therapeutic measures. The tachycardia response to the application of a magnet over the pacemaker could help in the differential diagnosis, and in some cases will be therapeutic, as in the case of a tachycardia-mediated pacemaker. Although these conditions are diagnosed and treated in hospitals with catheterization laboratories using the application programmer over the pacemaker, patients presenting in primary care clinic and emergency forced us to make a diagnosis and treat the haemodynamically unstable patient prior to referral. Copyright © 2012 Sociedad Española de Médicos de Atención Primaria (SEMERGEN). Publicado por Elsevier España. All rights reserved.

  5. Force and Power Measurements of a Functionally-Graded Chordwise-Flexible Flapping Wing

    Science.gov (United States)

    Mudbhari, Durlav; Erdogan, Malcolm; Moored, Keith

    2016-11-01

    Flyers and swimmers flap their wings and fins to propel themselves efficiently over long distances. A key element to achieve their high performance is the flexibility of their appendages. While numerous studies have shown that homogeneously flexible wings can enhance force production and efficiency, animals actually have wings with varying flexural rigidity along their chord and span. The goal of this study is to understand and characterize the force production and energetics of functionally-graded, chordwise flexible wings. A flapping wing composed of a rigid and a flexible region, that define a chordwise gradient in flexural rigidity, is used to model functionally-graded materials. By varying the ratio of the lengths of the rigid to flexible regions, the flexural rigidity of the flexible region, and the flapping frequency, the thrust production of a functionally-graded wing is directly measured in a wind tunnel. A novel vacuum chamber apparatus is used in conjunction with the wind tunnel measurements to reliably measure the aerodynamic power input and the propulsive efficiency. Limited flow visualization is performed with particle image velocimetry in order to connect the force production and energetics of the partially-flexible wing with its generated flow structures. Supported by the Office of Naval Research under Program Director Dr. Bob Brizzolara, MURI Grant Number N00014-14-1-0533.

  6. Circadian Pacemaker – Temperature Compensation

    NARCIS (Netherlands)

    Gerkema, Menno P.; Binder, Marc D.; Hirokawa, Nobutaka; Windhorst, Uwe

    2009-01-01

    One of the defining characteristics of circadian pacemakers and indicates the independence of the speed of circadian clock processes of environmental temperature. Mechanisms involved, so far not elucidated in full detail, entail at least two processes that are similarly affected by temperature chang

  7. First Degree Pacemaker Exit Block

    Directory of Open Access Journals (Sweden)

    Johnson Francis

    2016-10-01

    Full Text Available Usually atrial and ventricular depolarizations follow soon after the pacemaker stimulus (spike on the ECG. But there can be an exit block due to fibrosis at the electrode - tissue interface at the lead tip. This can increase the delay between the spike and atrial or ventricular depolarization.

  8. Correlação entre classe funcional e qualidade de vida em usuários de marcapasso cardíaco Correlation between functional class and quality of life among cardiac pacemaker users

    Directory of Open Access Journals (Sweden)

    TMB Cunha

    2007-10-01

    Full Text Available INTRODUÇÃO: Os crescentes avanços tecnológicos desenvolvidos para o tratamento de distúrbios de condução cardíaca vêm proporcionando aos pacientes melhores condições de vida. As escalas de classificação funcional e questionários de qualidade de vida (QV constituem uma forma suplementar de avaliação dos aspectos físicos, emocionais e funcionais dos pacientes. Entretanto, permanece a seguinte questão: existe correlação entre a classe funcional (CF e a percepção da QV em usuários de marcapasso (MP? OBJETIVO: O objetivo do estudo foi avaliar se existe correlação entre classe funcional (CF e QV em portadores de MP cardíaco definitivo. MÉTODOS: Foram avaliados 14 usuários de MP. Para avaliar CF, foi utilizada a escala de atividade específica proposta por Goldman, e, com objetivo de avaliação da QV, foi aplicado o questionário Aquarel associado ao SF-36. Com o objetivo de verificar se existe correlação entre as variáveis, foi aplicado o teste de correlação de Spearman, considerando como significativo aINTRODUCTION: Growing technological progress in treating patients with heart conduction disturbances has provided such patients with better life conditions. Functional classification (FC scales and quality of life (QOL questionnaires are additional means for evaluating patients' physical, emotional and functional characteristics. However, the question remains as to whether there is any association between FC and perception of QOL among pacemaker users. OBJECTIVE: To evaluate whether there is any correlation between FC and QOL among definitive cardiac pacemaker users. METHOD: Fourteen pacemaker users were evaluated. To assess FC, the specific activity scale proposed by Goldman was used. To evaluate QOL, the Aquarel questionnaire was used in association with SF-36. The Spearman correlation test was applied to investigate whether there was any association between the variables, considering p< 0.05 to be significant. The

  9. Radiotherapy for breast cancer and pacemaker; Radiotherapie pour un cancer du sein et stimulateur cardiaque

    Energy Technology Data Exchange (ETDEWEB)

    Menard, J.; Campana, F.; Bollet, M.A.; Dendale, R.; Fournier-Bidoz, N.; Marchand, V.; Mazal, A.; Fourquet, A.; Kirova, Y.M. [Oncologie-radiotherapie, institut Curie, 26, rue d' Ulm, 75005 Paris (France); Kirov, K.M.; Esteve, M. [Departement d' anesthesie-reanimation-douleur, institut Curie, 75005 Paris (France)

    2011-06-15

    Purpose. - Patients with permanent cardiac pacemakers occasionally require radiotherapy. Therapeutic Irradiation may cause pacemakers to malfunction due to the effects of ionizing radiation or electromagnetic interference. We studied the breast cancer patients who needed breast and/or chest wall and lymph node irradiation to assess the feasibility and tolerance in this population of patients. Patients and methods. - From November 2008 to December 2009, more than 900 patients received radiotherapy for their breast cancer in our department using megavoltage linear accelerator (X 4-6 MV and electrons). Among them, seven patients were with permanent pacemaker. All patients have been treated to the breast and chest wall and/or lymph nodes. Total dose to breast and/or chest wall was 50 Gy/25 fractions and 46 Gy/23 fractions to lymph nodes. Patients who underwent conserving surgery followed by breast irradiation were boosted when indicated to tumour bed with 16 Gy/8 fractions. All patients were monitored everyday in presence of radiation oncologist to follow the function of their pacemaker. All pacemakers were controlled before and after radiotherapy by the patients' cardiologist. Results. - Seven patients were referred in our department for postoperative breast cancer radiotherapy. Among them, only one patient was declined for radiotherapy and underwent mastectomy without radiotherapy. In four cases the pacemaker was repositioned before the beginning of radiotherapy. Six patients, aged between 48 and 84 years underwent irradiation for their breast cancer. Four patients were treated with conserving surgery followed by breast radiotherapy and two with mastectomy followed by chest wall and internal mammary chain, supra- and infra-clavicular lymph node irradiation. The dose to the pacemaker generator was kept below 2 Gy. There was no pacemaker dysfunction observed during the radiotherapy. Conclusion. - The multidisciplinary work with position change of the pacemaker

  10. Runaway pacemaker: a still existing complication and therapeutic guidelines

    DEFF Research Database (Denmark)

    Mickley, H; Andersen, C; Nielsen, L H

    1989-01-01

    Runaway pacemaker is a rare, but still existing potential lethal complication in permanent pacemakers. Within 4 1/2 years, we saw two cases of runaway pacemaker in patients with multiprogrammable, VVI pacemakers (Siemens-Elema, Model 668). In both cases a pacemaker-induced ventricular tachycardia...

  11. The Neural and Genetic Basis of Executive Function: Attention, Cognitive Flexibility, and Response Inhibition

    OpenAIRE

    Logue, Sheree F; Gould, Thomas J.

    2013-01-01

    Executive function is a collection of cognitive processes essential for higher order mental function. Processes involved in executive function include, but are not limited to, working memory, attention, cognitive flexibility, and impulse control. These complex behaviors are largely mediated by prefrontal cortical function but are modulated by dopaminergic, noradrenergic, serotonergic, and cholinergic input. The ability of these neurotransmitter systems to modulate executive function allows fo...

  12. Pacemakers, defibrillators, and direct current cardioversion.

    Science.gov (United States)

    Sgarbossa, E B; Black, I W; Maloney, J D

    1993-01-01

    Technology for pacemakers and automatic implantable defibrillators continues to evolve. Emphasis is placed not only on preventing cardiac death, but also on improving symptoms and quality of life. The basic antibradycardia function of pacemakers is complemented by highly sophisticated rate-responsive capabilities. The search for the perfect physiologic sensor has not ended; potential limitations of the systems currently available are considered in this review. Reports on outcome with pacing in different populations are also discussed. There have been two important advances in automatic implantable defibrillators. One is the introduction of the third generation defibrillator in clinical investigation. A tiered therapy (including antitachycardia pacing, cardioversion, and defibrillation) can now be programmed in the same device, with the protection of back-up antibradycardia pacing. The other remarkable innovation is the expanding use of nonthoracotomy techniques for implantable cardioverter-defibrillator placement. This approach permits the avoidance of a subcutaneous patch electrode in some cases, the system being entirely transvenous. Finally, recent insights on external cardioversion for atrial arrhythmias are briefly reviewed.

  13. Functional flexibility and acclimation of the thylakoid membrane.

    Science.gov (United States)

    Kanervo, Eira; Suorsa, Marjaana; Aro, Eva-Mari

    2005-12-01

    Light is an elusive substrate for the function of photosynthetic light reactions of photosynthesis in the thylakoid membrane. Therefore structural and functional dynamics, which occur in the timescale from seconds to several days, are required both at low and high light conditions. The best characterized short-time regulation mechanism at low light is a rapid state transition, resulting in higher absorption cross section of PSI at the expense of PSII. If the low light conditions continue, activation of the lhcb-genes and synthesis of the light-harvesting proteins will occur to optimize the functions of PSII and PSI. At high light, the transition to state 2 is completely inhibited, but the feedback de-excitation of absorbed energy as heat, known as the energy-dependent quenching (q(E)), is rapidly set up. It requires, at least, the DeltapH-dependent activation of violaxanthin de-epoxidase and involvement of the PsbS protein. Another crucial mechanism for protection against the high light stress is the PSII repair cycle. Furthermore, the water-water cycle, cyclic electron transfer around PSI and chlororespiration are important means induced under high irradiation, functioning mainly to avoid an excess production of reactive oxygen species.

  14. Flexible polymer solar cells based on Ag metallic grids and functional reduced graphene oxide composite electrode

    Science.gov (United States)

    Zheng, Qiao; Cheng, Shuying; Jia, Hongjie; Zhang, Hong; Liu, Si; Lai, Yunfeng; Yu, Jinling; Zhou, Haifang

    2017-10-01

    By combining the appropriate Ag metallic grids with a thin functional reduced graphene oxide (MGs/F-rGO) film, a suitable photoelectric flexible electrode of the polymer solar cells (PSCs) is obtained. The conductivity and transmission of the MGs/F-rGO composited films can be improved by HNO3 modified. The optimized sheet resistance and transmission of the flexible electrode achieve to 25 Ω □‑1 and 83% at 550 nm wavelength. Flexible PSCs with the MGs/F-rGO electrode show 5.63% power conversion efficiency. The photoelectric properties of the MGs/F-rGO film comparable with that of ITO substrates guarantee a high short current and an enhanced PCE of the solar cells. This method provides a feasible way for fabricating low-cost and flexible PSCs.

  15. Utilisation of cardiac pacemakers over a 20-year period : Results from a nationwide pacemaker registry

    NARCIS (Netherlands)

    de Vries, L. M.; Dijk, W. A.; Hooijschuur, C. A. M.; Leening, M. J. G.; Stricker, B. H. C.; van Hemel, N. M.

    2017-01-01

    The implantation of cardiac pacemakers has become a well-established therapy for conduction disorders and sinus node dysfunction. In many countries pacemaker registries have been initiated in order to collect information on patient characteristics, trends in numbers and the types of pacemakers used,

  16. [Telemedicine in pacemaker therapy and follow-up].

    Science.gov (United States)

    Schuchert, A

    2009-12-01

    Present-day remote systems for cardiovascular implantable electronic devices (CIEDs) provide, in contrast to previous solutions, a broad range of data about the patient and the implanted device ("remote control"). Telemedicine includes remote monitoring as well as remote follow-up: Remote monitoring is the continual interrogation of the device to detect patient- or device-related adverse events earlier than with standard follow-up visits. Remote follow-up aims to replace scheduled and unscheduled face-to-face follow-up visits due to the interrogation of the automatic pacemaker functions. Currently available remote systems, such as Home Monitoring, CareLink, Merlin.net, and Latitude, have in common that they interrogate the device, send these data to a server, and provide the data to the physician on a secured web site. Automatic wireless interrogation of the device is the preferred solution; however, the devices must have been equipped with a micro-antenna, which is usually restricted to more recent pacemaker models. Knowledge about remote control in pacemaker patients is limited, because most remote applications were evaluated in ICD and CRT patients. While the most frequently reported clinical event in pacemaker patients is atrial fibrillation, the impact in routine clinical follow-up still has to be evaluated in detail. Device-related adverse events are rare. Large, long-term, randomized trials are comparing remote and conventional approaches with the aim of demonstrating the benefits of telemedicine in this patient group.

  17. Differentially timed extracellular signals synchronize pacemaker neuron clocks.

    Directory of Open Access Journals (Sweden)

    Ben Collins

    2014-09-01

    Full Text Available Synchronized neuronal activity is vital for complex processes like behavior. Circadian pacemaker neurons offer an unusual opportunity to study synchrony as their molecular clocks oscillate in phase over an extended timeframe (24 h. To identify where, when, and how synchronizing signals are perceived, we first studied the minimal clock neural circuit in Drosophila larvae, manipulating either the four master pacemaker neurons (LNvs or two dorsal clock neurons (DN1s. Unexpectedly, we found that the PDF Receptor (PdfR is required in both LNvs and DN1s to maintain synchronized LNv clocks. We also found that glutamate is a second synchronizing signal that is released from DN1s and perceived in LNvs via the metabotropic glutamate receptor (mGluRA. Because simultaneously reducing Pdfr and mGluRA expression in LNvs severely dampened Timeless clock protein oscillations, we conclude that the master pacemaker LNvs require extracellular signals to function normally. These two synchronizing signals are released at opposite times of day and drive cAMP oscillations in LNvs. Finally we found that PdfR and mGluRA also help synchronize Timeless oscillations in adult s-LNvs. We propose that differentially timed signals that drive cAMP oscillations and synchronize pacemaker neurons in circadian neural circuits will be conserved across species.

  18. CONSTRUCTING A FLEXIBLE LIKELIHOOD FUNCTION FOR SPECTROSCOPIC INFERENCE

    Energy Technology Data Exchange (ETDEWEB)

    Czekala, Ian; Andrews, Sean M.; Mandel, Kaisey S.; Green, Gregory M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hogg, David W., E-mail: iczekala@cfa.harvard.edu [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY, 10003 (United States)

    2015-10-20

    We present a modular, extensible likelihood framework for spectroscopic inference based on synthetic model spectra. The subtraction of an imperfect model from a continuously sampled spectrum introduces covariance between adjacent datapoints (pixels) into the residual spectrum. For the high signal-to-noise data with large spectral range that is commonly employed in stellar astrophysics, that covariant structure can lead to dramatically underestimated parameter uncertainties (and, in some cases, biases). We construct a likelihood function that accounts for the structure of the covariance matrix, utilizing the machinery of Gaussian process kernels. This framework specifically addresses the common problem of mismatches in model spectral line strengths (with respect to data) due to intrinsic model imperfections (e.g., in the atomic/molecular databases or opacity prescriptions) by developing a novel local covariance kernel formalism that identifies and self-consistently downweights pathological spectral line “outliers.” By fitting many spectra in a hierarchical manner, these local kernels provide a mechanism to learn about and build data-driven corrections to synthetic spectral libraries. An open-source software implementation of this approach is available at http://iancze.github.io/Starfish, including a sophisticated probabilistic scheme for spectral interpolation when using model libraries that are sparsely sampled in the stellar parameters. We demonstrate some salient features of the framework by fitting the high-resolution V-band spectrum of WASP-14, an F5 dwarf with a transiting exoplanet, and the moderate-resolution K-band spectrum of Gliese 51, an M5 field dwarf.

  19. Constructing a Flexible Likelihood Function for Spectroscopic Inference

    Science.gov (United States)

    Czekala, Ian; Andrews, Sean M.; Mandel, Kaisey S.; Hogg, David W.; Green, Gregory M.

    2015-10-01

    We present a modular, extensible likelihood framework for spectroscopic inference based on synthetic model spectra. The subtraction of an imperfect model from a continuously sampled spectrum introduces covariance between adjacent datapoints (pixels) into the residual spectrum. For the high signal-to-noise data with large spectral range that is commonly employed in stellar astrophysics, that covariant structure can lead to dramatically underestimated parameter uncertainties (and, in some cases, biases). We construct a likelihood function that accounts for the structure of the covariance matrix, utilizing the machinery of Gaussian process kernels. This framework specifically addresses the common problem of mismatches in model spectral line strengths (with respect to data) due to intrinsic model imperfections (e.g., in the atomic/molecular databases or opacity prescriptions) by developing a novel local covariance kernel formalism that identifies and self-consistently downweights pathological spectral line “outliers.” By fitting many spectra in a hierarchical manner, these local kernels provide a mechanism to learn about and build data-driven corrections to synthetic spectral libraries. An open-source software implementation of this approach is available at http://iancze.github.io/Starfish, including a sophisticated probabilistic scheme for spectral interpolation when using model libraries that are sparsely sampled in the stellar parameters. We demonstrate some salient features of the framework by fitting the high-resolution V-band spectrum of WASP-14, an F5 dwarf with a transiting exoplanet, and the moderate-resolution K-band spectrum of Gliese 51, an M5 field dwarf.

  20. Glycinergic pacemaker neurons in preBötzinger Complex of neonatal mouse

    Science.gov (United States)

    Morgado-Valle, Consuelo; Baca, Serapio M.; Feldman, Jack L.

    2010-01-01

    The preBötzinger Complex (preBötC) is essential for normal respiratory rhythm generation in rodents, for which the underlying mechanisms remain unknown. Excitatory preBötC pacemaker neurons are proposed to be necessary for rhythm generation. Here we report the presence of a population of preBötC glycinergic pacemaker neurons. We used rhythmic in vitro transverse slice preparations from transgenic mice where neurons expressing the glycine transporter 2 (GlyT2) gene co-express enhanced green fluorescent protein (EGFP). We combined epifluorescence and whole-cell patch-clamp recording to study preBötC EGFP-labeled, i.e., glycinergic, inspiratory-modulated neurons with pacemaker properties. We defined glycinergic pacemaker neurons as those preBötC EGFP neurons that exhibited: 1) ectopic bursting in rhythmic slices when depolarized during their normally silent period, and; 2) bursting when depolarized in non-rhythmic slices (following AMPA receptor blockade). 42% of EGFP-labeled neurons were inspiratory (n=48 of 115), of which 23% (n=11 of 48 inspiratory; 10% of the total recorded) were pacemakers. We conclude that there is a population of preBötC inspiratory-modulated glycinergic, presumably inhibitory, pacemaker neurons that constitute a substantial fraction of all preBötC pacemaker neurons. These findings challenge contemporary models for respiratory rhythmogenesis that assume the excitatory nature of preBötC pacemaker neurons. Testable and non-trivial predictions of the functional role of excitatory and inhibitory pacemaker neurons need to be proposed and the necessary experiments performed. PMID:20219997

  1. RyR-NCX-SERCA local crosstalk ensures pacemaker cell function at rest and during the fight-or-flight reflex

    Science.gov (United States)

    Maltsev, Anna V.; Yaniv, Yael; Stern, Michael D.; Lakatta, Edward G.; Maltsev, Victor A.

    2015-01-01

    Rationale A recent study published in Circulation Research by Gao et al. employed SA node-targeted, incomplete Ncx1-knockout (KO) in mice to explore the role of the Na+/Ca2+ exchanger (NCX) in cardiac pacemaker. The authors concluded that NCX is required for increasing sinus rates, but not for maintaining resting heart rate. This conclusion was based, in part, on numerical model simulations performed by Gao et al. that reproduced their experimental results of unchanged action potentials in the KO SA node cells. The authors, however, did not simulate the NCX current (INCX), i.e. the subject of the study. Objective We extended numerical examinations to simulate INCX in their incomplete KO SA node cells that is crucial to interpret the study results. Methods and Results INCX and Ca2+ dynamics were simulated using different contemporary numerical models of SA node cells. We found that minimum diastolic Ca2+ levels and INCX amplitudes generated by remaining NCX molecules (only 20% of control) remained almost unchanged. Simulations using a new local Ca2+ control model indicate that these powerful compensatory mechanisms involve complex local cross-talk of Ca2+ cycling proteins and NCX. Specifically, lower NCX expression facilitates Ca2+-induced Ca2+ release and larger local Ca2+ releases that stabilize diastolic INCX. Further reduction of NCX expression results in arrhythmia and halt of automaticity. Conclusions Remaining NCX molecules in the incomplete KO model likely produce almost the same diastolic INCX as in wild-type cells. INCX contribution is crucially important for both basal automaticity of SA node cells and during the fight-or-flight reflex. PMID:24158576

  2. Pacemaker interactions induce reentrant wave dynamics in engineered cardiac culture

    Science.gov (United States)

    Borek, Bartłomiej; Shajahan, T. K.; Gabriels, James; Hodge, Alex; Glass, Leon; Shrier, Alvin

    2012-09-01

    Pacemaker interactions can lead to complex wave dynamics seen in certain types of cardiac arrhythmias. We use experimental and mathematical models of pacemakers in heterogeneous excitable media to investigate how pacemaker interactions can be a mechanism for wave break and reentrant wave dynamics. Embryonic chick ventricular cells are cultured invitro so as to create a dominant central pacemaker site that entrains other pacemakers in the medium. Exposure of those cultures to a potassium channel blocker, E-4031, leads to emergence of peripheral pacemakers that compete with each other and with the central pacemaker. Waves emitted by faster pacemakers break up over the slower pacemaker to form reentrant waves. Similar dynamics are observed in a modified FitzHugh-Nagumo model of heterogeneous excitable media with two distinct sites of pacemaking. These findings elucidate a mechanism of pacemaker-induced reentry in excitable media.

  3. Runaway pacemaker: a still existing complication and therapeutic guidelines

    DEFF Research Database (Denmark)

    Mickley, H; Andersen, C; Nielsen, L H

    1989-01-01

    Runaway pacemaker is a rare, but still existing potential lethal complication in permanent pacemakers. Within 4 1/2 years, we saw two cases of runaway pacemaker in patients with multiprogrammable, VVI pacemakers (Siemens-Elema, Model 668). In both cases a pacemaker-induced ventricular tachycardia...... pacemaker may be connected to the permanent pacing lead. Thereafter, the lead can be safely cut. As an alternative, a temporary transvenous pacing lead may be established prior to disconnecting the permanent pacing lead.......Runaway pacemaker is a rare, but still existing potential lethal complication in permanent pacemakers. Within 4 1/2 years, we saw two cases of runaway pacemaker in patients with multiprogrammable, VVI pacemakers (Siemens-Elema, Model 668). In both cases a pacemaker-induced ventricular tachycardia...

  4. An Investigation of Structure, Flexibility, and Function Variables that Discriminate Asymptomatic Foot Types.

    Science.gov (United States)

    Shultz, Sarah P; Song, Jinsup; Kraszewski, Andrew P; Hafer, Jocelyn F; Rao, Smita; Backus, Sherry; Hillstrom, Rajshree M; Hillstrom, Howard J

    2017-07-01

    It has been suggested that foot type considers not only foot structure (high, normal, low arch), but also function (overpronation, normal, oversupination) and flexibility (reduced, normal, excessive). Therefore, this study used canonical regression analyses to assess which variables of foot structure, function, and flexibility can accurately discriminate between clinical foot type classifications. The feet of 61 asymptomatic, healthy adults (18-77 years) were classified as cavus (N = 24), rectus (N = 54), or planus (N = 44) using standard clinical measures. Custom jigs assessed foot structure and flexibility. Foot function was assessed using an emed-x plantar pressure measuring device. Canonical regression analyses were applied separately to extract essential structure, flexibility, and function variables. A third canonical regression analysis was performed on the extracted variables to identify a combined model. The initial combined model included 30 extracted variables; however 5 terminal variables (malleolar valgus index, arch height index while sitting, first metatarsophalangeal joint laxity while standing, pressure-time integral and maximum contact area of medial arch) were able to correctly predict 80.7% of foot types. These remaining variables focused on specific foot characteristics (hindfoot alignment, arch height, midfoot mechanics, Windlass mechanism) that could be essential to discriminating foot type.

  5. Improving Students' Representational Flexibility in Linear-Function Problems: An Intervention

    Science.gov (United States)

    Acevedo Nistal, A.; Van Dooren, W.; Verschaffel, L.

    2014-01-01

    This study evaluates the effects of an intervention aimed at improving representational flexibility in linear-function problems. Forty-nine students aged 13-16 participated in the study. A pretest-intervention-posttest design with an experimental and control group was used. At pretest, both groups solved a choice test, where they could freely…

  6. 单腔起搏器心尖部起搏比例对心功能的影响%Effects of right ventricular apical pacing on heart function in patients with single-chamber pacemaker implantation

    Institute of Scientific and Technical Information of China (English)

    郑绪伟; 韩战营; 邱春光; 陈晓杰; 卢文杰

    2013-01-01

    目的 观察累计心室起搏百分比(CUM% VP,即起搏心率占总心率的百分比)对右室心尖部起搏患者心功能的影响.方法 采用队列研究设计,将86例NYHA心功能Ⅰ~Ⅱ级且符合纳入和排除标准的右室心尖单腔起搏患者分成两组进行随访观察.A组32例为CUM% VP ≥90%的患者,B组54例为CUM% VP< 90%的患者.以死亡、新发心力衰竭为终点,比较两组累积无终点事件生存率;同时观察左室射血分数(LVEF)、左室舒张末期内径(LVEDD)、QRS时间(QRSd)和从基线至随访结束时的改变(△LVEF、△LVEDD、△QRSd).结果 所有患者平均随访(34.8±11.7)个月,无失访和退出病例.随访结束时A组△LVEF、△LVEDD、△QRSd分别为(-5.4±7.3)%、(4.7±3.1)mm、(26.6±11.9)ms,B组分别为(2.5±5.9)%、(2.8±4.2)mm、(14.4±9.6)ms,两组比较差异均有统计学意义(P均<0.05).结论 频繁右室心尖部起搏使左室射血分数降低,左室舒张末期内径以及QRS时间增加,增加单腔心室起搏器置入患者心力衰竭发生危险,定期程控尽量减少心室起搏可以延缓心力衰竭的发生.%Objective To observe the effect of the cumulative percentage of ventricular pacing (CUM% VP) on heart function of patients with right ventricular apical pacing.Methods A cohort study was conducted among 86 patients with sick sinus syndrome (SSS) or atrioventricular block (AVB)after single-chamber ventricular pacemaker implantation.According to the cut-point 90% of CUM% VP,the patients were divided into group A (CUM% VP ≥90%,n =32) and group B (CUM% VP < 90%,n =54).The primary composite endpoint was defined as new-onset heart failure (NYHA class ≥ Ⅲ or hospitalization for heart failure) and death from all causes.The left ventricular ejection fraction(LVEF),left ventricular end-diastolic diameter(LVEDD) and the QRS duration were measured.Their absolute alterations(△LVEF,△LVEDD,△QRSd) as compared with the

  7. Validation of the Netherlands pacemaker patient registry

    NARCIS (Netherlands)

    Dijk, WA; Kingma, T; Hooijschuur, CAM; Dassen, WRM; Hoorntje, JCA; van Gelder, LM

    1997-01-01

    This paper deals with the validation of the information stored in the Netherlands central pacemaker patient database. At this moment the registry database contains information on more than 70500 patients, 85000 pacemakers and 90000 leads. The validation procedures consisted of an internal consistenc

  8. Feasibility of pacemaker therapy after dynamic cardiomyoplasty

    NARCIS (Netherlands)

    Van den Berg, MP; Nagelkerke, D; Brouwer, RMHJ; Mulder, H; De Boer, H; Crijns, HJGM

    1999-01-01

    A 54-year-old man presented with total atrioventricular (AV) block 3 months after dynamic cardiomyoplasty was performed because of heart failure due to idiopathic dilated cardiomyopathy. Though the cardiomyostimulator acted as a back-up pacemaker, a DDDR pacemaker was implanted to optimize hemodynam

  9. STUDY ON DYNAMICS, STABILITY AND CONTROL OF MULTI-BODY FLEXIBLE STRUCTURE SYSTEM IN FUNCTIONAL SPACE

    Institute of Scientific and Technical Information of China (English)

    徐建国; 贾军国

    2001-01-01

    The dynamics, stability and control problem of a kind of infinite dimensional system are studied in the functional space with the method of modern mathematics. First,the dynamical control model of the distributed parameter system with multi-body flexible and multi-topological structure was established which has damping, gyroscopic parts and constrained damping. Secondly, the necessary and sufficient condition of controllability and observability, the stability theory and asymptotic property of the system were obtained.These results expand the theory of the field about the dynamics and control of the system with multi-body flexible structure, and have important engineering significance.

  10. Biofilm on artificial pacemaker: fiction or reality?

    Science.gov (United States)

    Santos, Ana Paula Azevedo; Watanabe, Evandro; Andrade, Denise de

    2011-11-01

    Cardiac pacing through cardiac pacemaker is one of the most promising alternatives in the treatment of arrhythmias, but it can cause reactions natural or complex reactions, either early or late. This study aimed to describe the scientific evidence on the risk of infection and biofilm formation associated with cardiac pacemaker. This is a study of integrative literature review. It included 14 publications classified into three thematic categories: diagnosis (microbiological and/or clinical), complications and therapy of infections. Staphylococcus epidermidis and Staphylococcus aureus were the microorganisms most frequently isolated. It was not possible to determine the incidence of infection associated with pacemakers, since the studies were generally of prevalence. In terms of therapy, the complete removal of pacemakers stood out, especially in cases of suspected biofilm. Still controversial is the use of systemic antibiotic prophylaxis in reducing the incidence of infection associated with implantation of a pacemaker.

  11. The neural and genetic basis of executive function: attention, cognitive flexibility, and response inhibition.

    Science.gov (United States)

    Logue, Sheree F; Gould, Thomas J

    2014-08-01

    Executive function is a collection of cognitive processes essential for higher order mental function. Processes involved in executive function include, but are not limited to, working memory, attention, cognitive flexibility, and impulse control. These complex behaviors are largely mediated by prefrontal cortical function but are modulated by dopaminergic, noradrenergic, serotonergic, and cholinergic input. The ability of these neurotransmitter systems to modulate executive function allows for adaptation in cognitive behavior in response to changes in the environment. Because of the important role these neurotransmitter systems play in regulating executive function, changes in these systems can also have a grave impact on executive function. In addition, polymorphisms in genes associated with these neurotransmitters are associated with phenotypic differences in executive function. Understanding how these naturally occurring polymorphisms contribute to different executive function phenotypes will advance basic knowledge of cognition and potentially further understanding and treatment of mental illness that involve changes in executive function. In this review, we will examine the influence of dopamine, norepinephrine, serotonin, and acetylcholine on the following measures of executive function: attention, cognitive flexibility, and impulse control. We will also review the effects of polymorphisms in genes associated with these neurotransmitter systems on these measures of executive function. © 2013.

  12. The deployment of manufacturing flexibility as a function of company strategy

    Directory of Open Access Journals (Sweden)

    Carla Estorilio

    2013-08-01

    Full Text Available The flexibility is one of the priorities in manufacturing companies. However, the lack of guidelines for carrying out a critical analysis of the use of resources in manufacturing industry leads to a loss of process performance. This article describes a method to help companies identify the resources needed to provide manufacturing flexibility and meet the demands of their consumers while complying with company strategy. The literature related to flexibility is reviewed and a classification based on four levels is proposed: abilities, dimensions, elements and resources that provide flexibility. Based on this taxonomy and using the principles of QFD (Quality Function Deployment, a method is proposed that shows the correlation between these four levels, starting with customer demand and company strategy. The method was tested in an automobile manufacturing company, showing the applicability of the method. It highlighted the high degree of automation, which’s had serious problems related to restrictions on product mix. It can be inferred that this problem could be minimized by simplifying the tasks involved in the manufacture of car and by hiring more experienced, multi-skilled workers. The proposed method is different from those founded in the literature review because it deploys two levels more of flexibility, considering the QFD structure, and addresses strategic company issues.

  13. Hamstrings functional properties in athletes with high musculo-skeletal flexibility.

    Science.gov (United States)

    Moltubakk, M M; Eriksrud, O; Paulsen, G; Seynnes, O R; Bojsen-Møller, J

    2016-06-01

    The purpose of this study was to examine whether athletes with highly flexible hamstring muscle-tendon units display different passive and contractile mechanical properties compared with controls. Flexibility, passive, and active torque-angle properties were assessed in 21 female elite rhythmic gymnasts and 16 female age-matched athletes. Passive resistance to stretch was measured during knee extension with the hip fixed at 100° of flexion. Concentric isokinetic maximal voluntary knee flexion and extension torques were measured at 60°/s in the same position. Tests of flexibility and passive resistance to stretch indicated a greater flexibility in the gymnasts. Despite no differences between groups in knee flexion and extension peak torque, gymnasts reached knee flexion peak torque at more extended positions (longer muscle lengths) and displayed significantly different torque-angle relations. When active torque was corrected for passive resistance to stretch, differences increased, gymnasts producing more work, and maintaining ≥ 70% of peak torque over a larger range of joint excursion. In conclusion, individuals with a higher flexibility of the hamstrings MTU present a different torque-angle profile, favoring the production of flexion torque toward extended knee positions, displaying larger functional range of motion and a higher mechanical work output during knee flexion. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. 21 CFR 870.3620 - Pacemaker lead adaptor.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker lead adaptor. 870.3620 Section 870.3620...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3620 Pacemaker lead adaptor. (a) Identification. A pacemaker lead adaptor is a device used to adapt a pacemaker lead so that it...

  15. A fully implantable pacemaker for the mouse: from battery to wireless power.

    Directory of Open Access Journals (Sweden)

    Jacob I Laughner

    Full Text Available Animal models have become a popular platform for the investigation of the molecular and systemic mechanisms of pathological cardiovascular physiology. Chronic pacing studies with implantable pacemakers in large animals have led to useful models of heart failure and atrial fibrillation. Unfortunately, molecular and genetic studies in these large animal models are often prohibitively expensive or not available. Conversely, the mouse is an excellent species for studying molecular mechanisms of cardiovascular disease through genetic engineering. However, the large size of available pacemakers does not lend itself to chronic pacing in mice. Here, we present the design for a novel, fully implantable wireless-powered pacemaker for mice capable of long-term (>30 days pacing. This design is compared to a traditional battery-powered pacemaker to demonstrate critical advantages achieved through wireless inductive power transfer and control. Battery-powered and wireless-powered pacemakers were fabricated from standard electronic components in our laboratory. Mice (n = 24 were implanted with endocardial, battery-powered devices (n = 14 and epicardial, wireless-powered devices (n = 10. Wireless-powered devices were associated with reduced implant mortality and more reliable device function compared to battery-powered devices. Eight of 14 (57.1% mice implanted with battery-powered pacemakers died following device implantation compared to 1 of 10 (10% mice implanted with wireless-powered pacemakers. Moreover, device function was achieved for 30 days with the wireless-powered device compared to 6 days with the battery-powered device. The wireless-powered pacemaker system presented herein will allow electrophysiology studies in numerous genetically engineered mouse models as well as rapid pacing-induced heart failure and atrial arrhythmia in mice.

  16. A Fully Implantable Pacemaker for the Mouse: From Battery to Wireless Power

    Science.gov (United States)

    Zellmer, Erik R.; Weinheimer, Carla J.; MacEwan, Matthew R.; Cui, Sophia X.; Nerbonne, Jeanne M.; Efimov, Igor R.

    2013-01-01

    Animal models have become a popular platform for the investigation of the molecular and systemic mechanisms of pathological cardiovascular physiology. Chronic pacing studies with implantable pacemakers in large animals have led to useful models of heart failure and atrial fibrillation. Unfortunately, molecular and genetic studies in these large animal models are often prohibitively expensive or not available. Conversely, the mouse is an excellent species for studying molecular mechanisms of cardiovascular disease through genetic engineering. However, the large size of available pacemakers does not lend itself to chronic pacing in mice. Here, we present the design for a novel, fully implantable wireless-powered pacemaker for mice capable of long-term (>30 days) pacing. This design is compared to a traditional battery-powered pacemaker to demonstrate critical advantages achieved through wireless inductive power transfer and control. Battery-powered and wireless-powered pacemakers were fabricated from standard electronic components in our laboratory. Mice (n = 24) were implanted with endocardial, battery-powered devices (n = 14) and epicardial, wireless-powered devices (n = 10). Wireless-powered devices were associated with reduced implant mortality and more reliable device function compared to battery-powered devices. Eight of 14 (57.1%) mice implanted with battery-powered pacemakers died following device implantation compared to 1 of 10 (10%) mice implanted with wireless-powered pacemakers. Moreover, device function was achieved for 30 days with the wireless-powered device compared to 6 days with the battery-powered device. The wireless-powered pacemaker system presented herein will allow electrophysiology studies in numerous genetically engineered mouse models as well as rapid pacing-induced heart failure and atrial arrhythmia in mice. PMID:24194832

  17. Suicide attempt by complete self-removal of a 12-year-old permanent pacemaker system: case report.

    Science.gov (United States)

    Norgaard, Mette Lykke; Melchior, Thomas; Wagner, Thomas; Haugan, Ketil

    2014-01-01

    Psychological adaption after pacemaker implantation can be challenging in patients with psychiatric disease. Suicide by self-removal of a permanent pacemaker system is a rare phenomenon described in a few cases in patients with psychiatric disorders. We describe a case of attempted suicide by complete self-removal of a 12-year-old permanent pacemaker system in a 70-year-old male patient with a bipolar disorder and a history of previous suicide attempts. Suicide attempt by self-removal of a permanent pacemaker system is very rare. In patients with a history of psychiatric disease and previous suicide attempts, careful information about the function of a pacemaker should be given. © 2014 Wiley Periodicals, Inc.

  18. Pacemakers charging using body energy

    Directory of Open Access Journals (Sweden)

    Dinesh Bhatia

    2010-01-01

    Full Text Available Life-saving medical implants like pacemakers and defibrillators face a big drawback that their batteries eventually run out and patients require frequent surgery to have these batteries replaced. With the advent of technology, alternatives can be provided for such surgeries. To power these devices, body energy harvesting techniques may be employed. Some of the power sources are patient′s heartbeat, blood flow inside the vessels, movement of the body parts, and the body temperature (heat. Different types of sensors are employed, such as for sensing the energy from the heartbeat the piezoelectric and semiconducting coupled nanowires are used that convert the mechanical energy into electricity. Similarly, for sensing the blood flow energy, nanogenerators driven by ultrasonic waves are used that have the ability to directly convert the hydraulic energy in human body to electrical energy. Another consideration is to use body heat employing biothermal battery to generate electricity using multiple arrays of thermoelectric generators built into an implantable chip. These generators exploit the well-known thermocouple effect. For the biothermal device to work, it needs a 2°C temperature difference across it. But there are many parts of the body where a temperature difference of 5°C exists - typically in the few millimeters just below the skin, where it is planned to place this device. This study focuses on using body heat as an alternative energy source to recharge pacemaker batteries and other medical devices and prevent the possibility of life-risk during repeated surgery.

  19. Pacemakers charging using body energy.

    Science.gov (United States)

    Bhatia, Dinesh; Bairagi, Sweeti; Goel, Sanat; Jangra, Manoj

    2010-01-01

    Life-saving medical implants like pacemakers and defibrillators face a big drawback that their batteries eventually run out and patients require frequent surgery to have these batteries replaced. With the advent of technology, alternatives can be provided for such surgeries. To power these devices, body energy harvesting techniques may be employed. Some of the power sources are patient's heartbeat, blood flow inside the vessels, movement of the body parts, and the body temperature (heat). Different types of sensors are employed, such as for sensing the energy from the heartbeat the piezoelectric and semiconducting coupled nanowires are used that convert the mechanical energy into electricity. Similarly, for sensing the blood flow energy, nanogenerators driven by ultrasonic waves are used that have the ability to directly convert the hydraulic energy in human body to electrical energy. Another consideration is to use body heat employing biothermal battery to generate electricity using multiple arrays of thermoelectric generators built into an implantable chip. These generators exploit the well-known thermocouple effect. For the biothermal device to work, it needs a 2°C temperature difference across it. But there are many parts of the body where a temperature difference of 5°C exists - typically in the few millimeters just below the skin, where it is planned to place this device. This study focuses on using body heat as an alternative energy source to recharge pacemaker batteries and other medical devices and prevent the possibility of life-risk during repeated surgery.

  20. Vibration control for a rigid-flexible manipulator with full state constraints via Barrier Lyapunov Function

    Science.gov (United States)

    Cao, Fangfei; Liu, Jinkun

    2017-10-01

    Considering full state constraints, this paper designs a boundary controller for a two-link rigid-flexible manipulator via Barrier Lyapunov Function. The dynamic model of the two-link rigid-flexible manipulator is described by coupled ordinary differential equations- partial differential equations (ODEs-PDEs). Based on the original model without neglecting the high-frequency modes, boundary controller is proposed to regulate the joint positions and eliminate the elastic vibration simultaneously. To ensure that the full state constraints which include position, speed and vibration constraints are not transgressed, a Barrier Lyapunov Function is employed in the proposed controller. The asymptotic stability of the closed-loop system is rigorously proved by the LaSalle's Invariance Principle. Simulations are given to verify the effectiveness of the proposed controller with state constraints.

  1. High performance flexible pH sensor based on carboxyl-functionalized and DEP aligned SWNTs

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lu; Shao, Jinyou, E-mail: jyshao@mail.xjtu.edu.cn; Li, Xiangming; Zhao, Qiang; Nie, Bangbang; Xu, Chuan; Ding, Haitao

    2016-11-15

    Highlights: • The flexible chemiresistive pH sensor based on two-terminal microsensors eliminating the need for a reference electrode, is simple in structure and can be fabricated on a variety of substrates such as PET, PI and PVC. • SWNTs as an ideal one dimensional material are carboxyl-functionalized to make the pH sensor show high sensitivity and outstanding flexibility for practical applications. • DEP technique is used to manipulate and position SWNTs into appropriate locations and desired formations to improve the metal-nanotube interface and highly rapid detection of pH value, resulting in better overall device performance. • Mechanical bendability of the pH sensor, which arises from the combination of flexible PET substrates and SWNTs, offer a significant improvement for applications that are difficult or impossible to achieve with traditional sensors on rigid substrates. - Abstract: The detection and control of the pH is very important in many biomedical and chemical reaction processes. A miniaturized flexible pH sensor that is light weight, robust, and conformable is very important in many applications, such as multifunctional lab-on-a-chip systems or wearable biomedical devices. In this work, we demonstrate a flexible chemiresistive pH sensor based on dielectrophoresis (DEP) aligned carboxyl-functionalized single-walled carbon nanotubes (SWNTs). Decorated carboxyl groups can react with hydrogen (H{sup +}) and hydroxide (OH{sup −}) ions, enabling the sensor to be capable of sensing the pH. DEP is used to deposit well-organized and highly aligned SWNTs in desired locations, which improves the metal-nanotube interface and highly rapid detection of the pH, resulting in better overall device performance. When pH buffer solutions are dropped onto such SWNTs, the H{sup +} and OH{sup −} ions caninteract with the carboxyl groups and affect the generation of holes and electrons in the SWNTs, leading to resistance variations in the SWNTs. The results

  2. Tribo-Mechanical Investigation of the Functional Components used in Flexible Energy Harvesting Devices

    Science.gov (United States)

    Morris, Nicholas J.

    During the previous decade, the development of energy harvesting devices based on piezoelectric materials has garnered great interest. The ability to capture ambient mechanical energy and convert it to useable electricity is a potential solution to the ever-growing energy crisis. One of the most attractive functional materials used in these devices is zinc oxide (ZnO). This material's relative low cost and ease of large-area processing has spurred numerous device designs based around it. The ability to grow ZnO nanostructures of various geometries with low-temperature chemical methods makes this material even more attractive for flexible devices. Although numerous device architectures have been developed, the long-term mechanical reliability has not been addressed. This work focuses on the fabrication and mechanical failure analysis of the flexible components typically used in piezoelectric energy harvesting devices. A three-phase iterative design process was used to fabricate prototypical piezoelectric nanogenerators, based on ZnO nanowires. An output of several millivolts was achieved under normal contact and microtensile loading, but device failure occurred after only a few loading cycles, in all cases. Ex situ failure analysis confirmed the primary sources of failure, which became the focus of further, component-level studies. Failure was primarily seen in the flexible electrodes of the nanogenerating devices, but was also observed in the functional piezoelectric layer itself. Flexible electrodes comprised of polyester substrates with transparent conductive oxide (TCO) coatings were extensively investigated under various loading scenarios to mimic tribo-mechanical stresses applied during fabrication and use in flexible contact-based devices. The durability of these films was explored using microtensile testing, spherical nanoindentation, controlled mechanical buckling, stress corrosion cracking, and shear-contact reciprocating wear. The electro

  3. Pregnancy in sick sinus syndrome with pacemaker - two cases.

    Science.gov (United States)

    Parveen, T; Begum, F; Akhter, N; Sharmin, F

    2013-04-01

    Sick sinus syndrome is a generalized abnormality of cardiac impulse formation that may be caused by extrinsic causes or by intrinsic disease of the sinus node making it unable to perform pace making function. It can be manifested for the first time in pregnancy. First case was diagnosed as sick sinus syndrome at 8 weeks of gestation having Mobitz type I heart block (Wenckebach block), and needed temporary pacemaker during caesarean section. Second case was diagnosed at 24 weeks of gestation having complete heart block and needed permanent pacemaker at 38 weeks of gestation due to exaggeration of the symptoms. Both the cases were dealt successfully by caesarean section under general anesthesia in close collaboration with cardiologists and anesthesiologists.

  4. Fast Fabrication of Flexible Functional Circuits Based on Liquid Metal Dual-Trans Printing.

    Science.gov (United States)

    Wang, Qian; Yu, Yang; Yang, Jun; Liu, Jing

    2015-11-25

    A dual-trans method to print the first functional liquid-metal circuit layout on poly(vinyl chloride) film, and then transfer it into a poly(dimethylsiloxane) substrate through freeze phase transition processing for the fabrication of a flexible electronic device. A programmable soft electronic band and a temperature-sensing module wirelessly communicate with a mobile phone, demonstrating the efficiency and capability of the method.

  5. Functional Performance Evaluation of the Northwestern University Flexible Subischial Vacuum (NU-FlexSIV) Socket for Persons with Transfemoral Amputation

    Science.gov (United States)

    2016-10-01

    AWARD NUMBER: W81XWH-15-1-0708 TITLE: Functional Performance Evaluation of the Northwestern University Flexible Subischial Vacuum (NU-FlexSIV...University Flexible Subischial Vacuum (NU-FlexSIV) Socket for Persons with Transfemoral Amputation 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-15-1...the Northwestern University Flexible Sub-Ischial Vacuum (NU-FlexSIV) Socket) with the current standard of care socket (the Ischial Containment (IC

  6. Flexible parametric modelling of cause-specific hazards to estimate cumulative incidence functions

    Science.gov (United States)

    2013-01-01

    Background Competing risks are a common occurrence in survival analysis. They arise when a patient is at risk of more than one mutually exclusive event, such as death from different causes, and the occurrence of one of these may prevent any other event from ever happening. Methods There are two main approaches to modelling competing risks: the first is to model the cause-specific hazards and transform these to the cumulative incidence function; the second is to model directly on a transformation of the cumulative incidence function. We focus on the first approach in this paper. This paper advocates the use of the flexible parametric survival model in this competing risk framework. Results An illustrative example on the survival of breast cancer patients has shown that the flexible parametric proportional hazards model has almost perfect agreement with the Cox proportional hazards model. However, the large epidemiological data set used here shows clear evidence of non-proportional hazards. The flexible parametric model is able to adequately account for these through the incorporation of time-dependent effects. Conclusion A key advantage of using this approach is that smooth estimates of both the cause-specific hazard rates and the cumulative incidence functions can be obtained. It is also relatively easy to incorporate time-dependent effects which are commonly seen in epidemiological studies. PMID:23384310

  7. Identifying Functional Requirements for Flexible Airspace Management Concept Using Human-In-The-Loop Simulations

    Science.gov (United States)

    Lee, Paul U.; Bender, Kim; Pagan, Danielle

    2011-01-01

    Flexible Airspace Management (FAM) is a mid- term Next Generation Air Transportation System (NextGen) concept that allows dynamic changes to airspace configurations to meet the changes in the traffic demand. A series of human-in-the-loop (HITL) studies have identified procedures and decision support requirements needed to implement FAM. This paper outlines a suggested FAM procedure and associated decision support functionality based on these HITL studies. A description of both the tools used to support the HITLs and the planned NextGen technologies available in the mid-term are presented and compared. The mid-term implementation of several NextGen capabilities, specifically, upgrades to the Traffic Management Unit (TMU), the initial release of an en route automation system, the deployment of a digital data communication system, a more flexible voice communications network, and the introduction of a tool envisioned to manage and coordinate networked ground systems can support the implementation of the FAM concept. Because of the variability in the overall deployment schedule of the mid-term NextGen capabilities, the dependency of the individual NextGen capabilities are examined to determine their impact on a mid-term implementation of FAM. A cursory review of the different technologies suggests that new functionality slated for the new en route automation system is a critical enabling technology for FAM, as well as the functionality to manage and coordinate networked ground systems. Upgrades to the TMU are less critical but important nonetheless for FAM to be fully realized. Flexible voice communications network and digital data communication system could allow more flexible FAM operations but they are not as essential.

  8. Correlação entre a qualidade de vida, classe funcional e idade em portadores de marca-passo cardíaco Correlation between quality of life, functional class and age in patients with cardiac pacemaker

    Directory of Open Access Journals (Sweden)

    Juliana Bassalobre Carvalho Borges

    2013-03-01

    Full Text Available OBJETIVO: Avaliar se existe correlação entre qualidade de vida e classe funcional em pacientes no pós-implante de marca-passo cardíaco, e sua relação com idade. MÉTODOS: Investigados 107 pacientes de ambos os sexos (49,5% do sexo feminino e 50,5% do sexo masculino, tempo médio de implante 6,36º ±2,99 meses e média de idade 69,3º ±12,6 anos. Para avaliação da classe funcional, foi utilizada escala proposta por Goldman e para qualidade de vida, questionário AQUAREL associado ao SF-36. Realizada análise estatística pela correlação de Spearman, com significância de 5%. RESULTADOS: Foram observadas correlações negativas entre qualidade de vida e classe funcional: AQUAREL nos três domínios, desconforto no peito (r=-0,197, P=0,042, dispneia (r=-0,508, P =0,000, arritmia (r=-0,271, P=0,005 e, no SF-36 nos oito domínios. Em relação à idade, correlação negativa com Capacidade Funcional do SF-36 (r=-0,338, P=0,000 e não se observou correlação com AQUAREL. Entre idade e classe funcional observou-se correlação positiva (r=0,237, P=0,014. CONCLUSÃO: Neste estudo, encontrou-se correlação negativa entre qualidade de vida e classe funcional, evidenciando nesta amostra que os pacientes pertencentes a melhor classe funcional apresentaram melhor qualidade de vida. Conforme maior idade, pior a qualidade de vida em Capacidade Funcional e em classe funcional. Sugere-se, que idade e classe funcional influenciam qualidade de vida e as escalas de classificação funcional podem constituir um dos instrumentos que integram a avaliação e refletem a qualidade de vida em portadores de marca-passo.OBJECTIVE: To evaluate whether there is a correlation between quality of life and functional class in early heart pacemaker in patients, and its relationship with age. METHODS: 107 patients of both sexes (49.5% female/50.5% male were investigated, average implant time of 6.36 months (±2.99, and average age of 69.3 years (±12.6. To assess the

  9. [Management of pacemaker patients by bathtub ECG].

    Science.gov (United States)

    Mizukami, H; Togawa, T; Toyoshima, T; Ishijima, M

    1989-01-01

    We evaluated the efficacy of a new method for recording electrocardiogram (ECG) of pacemaker patients in bathtub (bathtub ECG). ECG from the pacemaker implanted patients in the bathtub with tap water was recorded through three silver/silver chloride electrodes (4 x 4 cm) fitted on the inside wall of bathtub. Electric signal was connected to the isolated amplifier and recorded on the strip chart recorder. Contrast to the conventional method for recording standard ECG, bathtub ECG does not require body surface electrodes and is recorded at patients home. Although the amplitude of bathtub ECG was reduced approximately to a quarter of standard ECG, cardiac arrhythmia can be easily interpreted by bathtub ECG. In patients with pacemaker system, the amplitude of the pacing pulse recorded by bathtub ECG was much larger than that of QRS complex recorded by standard ECG. Therefore, we conclude that bathtub ECG would be a suitable method to follow up patients with pacemaker system.

  10. How Will a Pacemaker Affect My Lifestyle?

    Science.gov (United States)

    ... close to a security system metal detector. Notify security staff if you have a pacemaker. Also, stay at least 2 feet away from industrial welders and electrical generators. Some medical procedures can ...

  11. Large-Deformation Displacement Transfer Functions for Shape Predictions of Highly Flexible Slender Aerospace Structures

    Science.gov (United States)

    Ko, William L.; Fleischer, Van Tran

    2013-01-01

    Large deformation displacement transfer functions were formulated for deformed shape predictions of highly flexible slender structures like aircraft wings. In the formulation, the embedded beam (depth wise cross section of structure along the surface strain sensing line) was first evenly discretized into multiple small domains, with surface strain sensing stations located at the domain junctures. Thus, the surface strain (bending strains) variation within each domain could be expressed with linear of nonlinear function. Such piecewise approach enabled piecewise integrations of the embedded beam curvature equations [classical (Eulerian), physical (Lagrangian), and shifted curvature equations] to yield closed form slope and deflection equations in recursive forms.

  12. Micro and nanopatterning of functional materials on flexible plastic substrates via site-selective surface modification using oxygen plasma

    NARCIS (Netherlands)

    George, A.; Stawski, T.M.; Unnikrishnan, S.; Veldhuis, S.A.; Elshof, J.E. ten

    2012-01-01

    A simple and cost effective methodology for large area micro and nanopatterning of a wide range of functional materials on flexible substrates is presented. A hydrophobic-hydrophilic chemical contrast was patterned on surfaces of various flexible plastic substrates using molds and shadow masks with

  13. Micro and nanopatterning of functional materials on flexible plastic substrates via site-selective surface modification using oxygen plasma

    NARCIS (Netherlands)

    George, A.; Stawski, T.M.; Unnikrishnan, S.; Veldhuis, S.A.; Elshof, J.E. ten

    2012-01-01

    A simple and cost effective methodology for large area micro and nanopatterning of a wide range of functional materials on flexible substrates is presented. A hydrophobic-hydrophilic chemical contrast was patterned on surfaces of various flexible plastic substrates using molds and shadow masks with

  14. Micro- and nanopatterning of functional materials on flexible plastic substrates via site-selective surface modification using oxygen plasma

    NARCIS (Netherlands)

    George, A.; Stawski, T.M.; Unnikrishnan, S.; Veldhuis, S.A.; Elshof, ten J.E.

    2012-01-01

    A simple and cost effective methodology for large area micro and nanopatterning of a wide range of functional materials on flexible substrates is presented. A hydrophobic-hydrophilic chemical contrast was patterned on surfaces of various flexible plastic substrates using molds and shadow masks with

  15. Case study thoracic radiotherapy in an elderly patient with pacemaker: The issue of pacing leads

    Energy Technology Data Exchange (ETDEWEB)

    Kirova, Youlia M., E-mail: youlia.kirova@curie.net [Department of Radiation Oncology, Institut Curie, Paris (France); Menard, Jean; Chargari, Cyrus; Mazal, Alejandro [Department of Radiation Oncology, Institut Curie, Paris (France); Kirov, Krassen [Department of Anesthesiology and Reanimation, Institut Curie, Paris (France)

    2012-07-01

    To assess clinical outcome of patients with pacemaker treated with thoracic radiation therapy for T8-T9 paravertebral chloroma. A 92-year-old male patient with chloroma presenting as paravertebral painful and compressive (T8-T9) mass was referred for radiotherapy in the Department of Radiation Oncology, Institut Curie. The patient presented with cardiac dysfunction and a permanent pacemaker that had been implanted prior. The decision of Multidisciplinary Meeting was to deliver 30 Gy in 10 fractions for reducing the symptoms and controlling the tumor growth. The patient received a total dose of 30 Gy in 10 fractions using 4-field conformal radiotherapy with 20-MV photons. The dose to pacemaker was 0.1 Gy but a part of the pacing leads was in the irradiation fields. The patient was treated the first time in the presence of his radiation oncologist and an intensive care unit doctor. Moreover, the function of his pacemaker was monitored during the entire radiotherapy course. No change in pacemaker function was observed during any of the radiotherapy fractions. The radiotherapy was very well tolerated without any side effects. The function of the pacemaker was checked before and after the radiotherapy treatment by the cardiologist and no pacemaker dysfunction was observed. Although updated guidelines are needed with acceptable dose criteria for implantable cardiac devices, it is possible to treat patients with these devices and parts encroaching on the radiation field. This case report shows we were able to safely treat our patient through a multidisciplinary approach, monitoring the patient during each step of the treatment.

  16. Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces

    Science.gov (United States)

    Kamali, Seyedeh Mahsa; Arbabi, Amir; Arbabi, Ehsan; Horie, Yu; Faraon, Andrei

    2016-05-01

    Physical geometry and optical properties of objects are correlated: cylinders focus light to a line, spheres to a point and arbitrarily shaped objects introduce optical aberrations. Multi-functional components with decoupled geometrical form and optical function are needed when specific optical functionalities must be provided while the shapes are dictated by other considerations like ergonomics, aerodynamics or aesthetics. Here we demonstrate an approach for decoupling optical properties of objects from their physical shape using thin and flexible dielectric metasurfaces which conform to objects' surface and change their optical properties. The conformal metasurfaces are composed of silicon nano-posts embedded in a polymer substrate that locally modify near-infrared (λ=915 nm) optical wavefronts. As proof of concept, we show that cylindrical lenses covered with metasurfaces can be transformed to function as aspherical lenses focusing light to a point. The conformal metasurface concept is highly versatile for developing arbitrarily shaped multi-functional optical devices.

  17. Structures of mesophilic and extremophilic citrate synthases reveal rigidity and flexibility for function.

    Science.gov (United States)

    Wells, Stephen A; Crennell, Susan J; Danson, Michael J

    2014-10-01

    Citrate synthase (CS) catalyses the entry of carbon into the citric acid cycle and is highly-conserved structurally across the tree of life. Crystal structures of dimeric CSs are known in both "open" and "closed" forms, which differ by a substantial domain motion that closes the substrate-binding clefts. We explore both the static rigidity and the dynamic flexibility of CS structures from mesophilic and extremophilic organisms from all three evolutionary domains. The computational expense of this wide-ranging exploration is kept to a minimum by the use of rigidity analysis and rapid all-atom simulations of flexible motion, combining geometric simulation and elastic network modeling. CS structures from thermophiles display increased structural rigidity compared with the mesophilic enzyme. A CS structure from a psychrophile, stabilized by strong ionic interactions, appears to display likewise increased rigidity in conventional rigidity analysis; however, a novel modified analysis, taking into account the weakening of the hydrophobic effect at low temperatures, shows a more appropriate decreased rigidity. These rigidity variations do not, however, affect the character of the flexible dynamics, which are well conserved across all the structures studied. Simulation trajectories not only duplicate the crystallographically observed symmetric open-to-closed transitions, but also identify motions describing a previously unidentified antisymmetric functional motion. This antisymmetric motion would not be directly observed in crystallography but is revealed as an intrinsic property of the CS structure by modeling of flexible motion. This suggests that the functional motion closing the binding clefts in CS may be independent rather than symmetric and cooperative.

  18. Pointwise functions for flexible implementation of crustal deformation physics in PyLith

    Science.gov (United States)

    Aagaard, B.; Knepley, M.; Williams, C. A.

    2015-12-01

    The next stage of development for PyLith, a flexible, open-source finite-element code (http://geodynamics.org/cig/software/pylith/) for modeling quasi-static and dynamic crustal deformation with an emphasis earthquake faulting, focuses on refactoring the code to provide greater flexibility in support of a broader range of physics, discretizations, and optimizations for a variety of computer hardware. We separate the finite-element integration into a discretization-specific portion and discretization-independent pointwise functions associated with the governing equations. The discretization-specific portion is designed to accommodate arbitrary order finite elements and multiple implementations for optimization targeting specific hardware (e.g., CPU and GPU). The pointwise functions encapsulate the physics, including the governing equations and rheologies. Users can easily extend the code by adding new pointwise functions to implement different rheologies and/or governing equations. PyLith currently includes pointwise functions for quasi-static and dynamic elasticity for several elastic, viscoelastic, and elastoplastic rheologies. We plan to add pointwise functions for coupling of elasticity with fluid flow and incompressible elasticity. Tight integration with the Portable, Extensible Toolkit for Scientific Computation (PETSc) provides support for a wide range of linear and nonlinear solvers and time-stepping algorithms.

  19. How to test mode switching in pacemakers implanted in patients: the MOST study.

    Science.gov (United States)

    Padeletti, Luigi; Gasparini, Maurizio; Porciani, Maria Cristina; Pieragnoli, Paolo; Colella, Andrea; Michelucci, Antonio; Proclemer, Alessandro; Tognarini, Stefano; Mantica, Massimo; Coltorti, Fernando; Corbucci, Giorgio; Sutton, Richard

    2002-02-01

    Optimal management of atrial arrhythmias with dual chamber pacemakers requires proper performance of automatic mode switching (AMS). The aim of this study was to develop a reliable technique to test the AMS function by using an external electronic device capable of mimicking the occurrence of supraventricular arrhythmias (Supraventricular Arrhythmia Simulator [SAS]). The SAS delivers low voltage pulse trains (200 mV, 20 ms) through two skin electrodes. Each pulse train lasts 15 seconds and starts synchronously with a pacing pulse of the implanted pacemaker to avoid interference from the operator. The pulse train rate is set at 350, 250, and 160 beats/min to simulate AF, atrial flutter, and atrial tachycardia (AT), respectively. Thirty-five patients implanted with Vitatron pacemakers, whose AMS system has been previously validated, were enrolled. Atrial and ventricular sensing were programmed in unipolar mode at 0.5 mV and in bipolar mode at > 2 mV, respectively. All pulses from the SAS were detected by the atrial channel at an amplitude ranging from 1 to 3 mV. The test proved to be safe and reliable at rest and during exercise. AMS occurred immediately at onset or at offset of atrial arrhythmias, and no adverse interference on pacemaker function was seen from the SAS. In conclusion, the described technique and the SAS are safe and reliable for patient and pacemaker function and can be proposed as a useful method to verify proper performance of AMS function irrespective of the type of implanted devices.

  20. First percutaneous Micra leadless pacemaker implantation and tricuspid valve repair with MitraClip NT for lead-associated severe tricuspid regurgitation.

    Science.gov (United States)

    Tang, Gilbert H L; Kaple, Ryan; Cohen, Martin; Dutta, Tanya; Undemir, Cenap; Ahmad, Hasan; Poniros, Angelica; Bennett, Joanne; Feng, Cheng; Lansman, Steven

    2017-02-03

    Pacemaker lead-associated severe tricuspid regurgitation (TR) can lead to right heart failure and poor prognosis. Surgery in these patients carries significant morbidities. We describe a successful treatment of symptomatic severe TR by leadless pacemaker implantation followed by tricuspid valve (TV) repair with the MitraClip NT. A 71-year-old frail female with poor functional status, chronic atrial fibrillation and permanent pacemaker implantation in 2012 presented with symptomatic moderate-severe mitral regurgitation (MR) and severe TR with the pacemaker lead as the culprit. She was deemed extreme risk for double valve surgery and, because of her pacemaker dependency, the decision was to stage her interventions first with transcatheter mitral repair, then laser lead extraction and leadless pacemaker implantation to free the TV from tethering, then TV repair. An obstructive LAD lesion was identified and treated during mitral repair with the MitraClip NT. The Micra leadless pacemaker implantation and subsequent TV repair with the MitraClip NT were successful and the patient's MR improved to mild and TR to moderate, respectively. We report here a first successful transcatheter strategy to treat lead-associated severe TR by leadless pacemaker and MitraClip. Removing the pacemaker lead relieved leaflet tethering and improved the reparability of the TV.

  1. Utilisation of cardiac pacemakers over a 20-year period: Results from a nationwide pacemaker registry

    NARCIS (Netherlands)

    L.M. de Vries (Laura); W.A. Dijk (Arnold); C.A.M. Hooijschuur (C. A M); M.J.G. Leening (Maarten); B.H.Ch. Stricker (Bruno); N.M. van Hemel (Norbert)

    2017-01-01

    textabstractThe implantation of cardiac pacemakers has become a well-established therapy for conduction disorders and sinus node dysfunction. In many countries pacemaker registries have been initiated in order to collect information on patient characteristics, trends in numbers and the types of pace

  2. Pacemaker diagnostics in atrial fibrillation: limited usefulness for therapy initiation in a pacemaker practice.

    Science.gov (United States)

    Yedlapati, Neeraja; Fisher, John D

    2014-09-01

    We aimed to determine the practical value of pacemaker diagnostics for atrial fibrillation (AF) in an unselected general pacemaker practice, specifically workflow and initiation of anticoagulation or antiarrhythmic drug (AAD) therapy. We prospectively followed consecutive pacemaker interrogations over a period of 1 year to identify patients with AF (burden from 1% to 99%). We contacted referring physicians with AF details, and then determined whether the information resulted in therapeutic changes. Of the 1,100 pacemakers interrogated, 728 were dual chamber (DDDs) with AF diagnostic capability. AF was recorded in 73 (10%) but seven had limited information, leaving 66 patients; of these, 42 (63%) patients were already anticoagulated and in five (7%) patients, anticoagulation had been stopped because of complications. Initial diagnosis of AF was made by the pacemaker in 17 patients (26% of 66; 2% of 728); four (6% of 66) patients were newly initiated on anticoagulation. Of the 66 patients, 17 patients were already on AADs; 49 (74%) had satisfactory rate control or had other issues; only two (3% of 66; 0.3% of 728) received new AADs. Of 728 patients with DDD pacemakers, only 17 were newly discovered to have AF, and six (0.8%) had changes in medications based on the pacemaker data. Adding pacemaker-derived data to existing clinical information had little therapeutic impact, due to a combination of cumbersome workflow, and because AF was usually known to practitioners. Developments in automated monitoring systems may provide more accessible and therapeutically useful information. ©2014 Wiley Periodicals, Inc.

  3. Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces

    CERN Document Server

    Kamali, Seyedeh Mahsa; Arbabi, Ehsan; Horie, Yu; Faraon, Andrei

    2015-01-01

    Physical geometry and optical properties of objects are correlated: cylinders focus light to a line, spheres to a point, and arbitrarily shaped objects introduce optical aberrations. Multi-functional components with decoupled geometrical form and optical function are needed when specific optical functionalities must be provided while the shapes are dictated by other considerations like ergonomics, aerodynamics, or esthetics. Here we demonstrate an approach for decoupling optical properties of objects from their physical shape using thin and highly transparent flexible dielectric metasurfaces which conform to objects' surface and change their optical properties. The conformal metasurfaces are composed of silicon nano-posts embedded in a polymer substrate that locally modify optical wavefronts. As proof of concept, we show that cylindrical lenses covered with metasurfaces can be transformed to function as aspherical lenses focusing light to a point. The conformal metasurface concept introduces a novel paradigm ...

  4. A safer and flexible method for the oxygen functionalization of carbon nanotubes by nitric acid vapors

    Energy Technology Data Exchange (ETDEWEB)

    Santangelo, Saveria, E-mail: saveria.santangelo@unirc.it [Dipartimento di Ingegneria Civile, dell’Energia, dell’Ambiente e dei Materiali (DICEAM), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Piperopoulos, Elpida [Dipartimento di Ingegneria Eletronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Fazio, Enza [Dipartimento di Fisica e di Scienze della Terra (DFST), Università di Messina, 98166 Messina (Italy); Faggio, Giuliana [Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile (DIIES), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Ansari, Shabana [Dipartimento di Ingegneria Eletronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Lanza, Maurizio [Istituto per i Processi Chimico Fisici (IPCF) del CNR, 98158 Messina (Italy); Neri, Fortunato [Dipartimento di Fisica e di Scienze della Terra (DFST), Università di Messina, 98166 Messina (Italy); Messina, Giacomo [Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile (DIIES), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Milone, Candida [Dipartimento di Ingegneria Eletronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy)

    2014-06-01

    The functionalization by nitric acid vapors at azeotropic concentration has been recently proposed to eliminate drawbacks of the widely utilized liquid phase functionalization method. This work suggests to exploit the so-called “salt effect” to improve the vapor phase oxidation method in terms of safety and flexibility. Increasing the relative volatility of acid, the addition of Mg(NO{sub 3}){sub 2} salt to the HNO{sub 3} + H{sub 2}O solution allows (i) obtaining vapors with HNO{sub 3} at the azeotropic concentration from a more diluted liquid solution (i.e. operating under safer conditions), and (ii) varying the concentration of HNO{sub 3} in the vapor phase even above the azeotropic concentration limit (with improved process flexibility). High-resolution transmission electron microscopy, thermo-gravimetry, Raman spectroscopy and X-ray photoemission spectroscopy systematic analyses are carried out on pristine and oxidized nanotubes in order to assess their functionalization degree, surface chemistry and structural evolution. The most relevant finding of this preliminary study is that the nanotube functionalization extent increases linearly with the HNO{sub 3} vapor concentration.

  5. Alterations in the functional neural circuitry supporting flexible choice behavior in autism spectrum disorders

    Science.gov (United States)

    D'Cruz, A-M; Mosconi, M W; Ragozzino, M E; Cook, E H; Sweeney, J A

    2016-01-01

    Restricted and repetitive behaviors, and a pronounced preference for behavioral and environmental consistency, are distinctive characteristics of autism spectrum disorder (ASD). Alterations in frontostriatal circuitry that supports flexible behavior might underlie this behavioral impairment. In an functional magnetic resonance imaging study of 17 individuals with ASD, and 23 age-, gender- and IQ-matched typically developing control participants, reversal learning tasks were used to assess behavioral flexibility as participants switched from one learned response choice to a different response choice when task contingencies changed. When choice outcome after reversal was uncertain, the ASD group demonstrated reduced activation in both frontal cortex and ventral striatum, in the absence of task performance differences. When the outcomes of novel responses were certain, there was no difference in brain activation between groups. Reduced activation in frontal cortex and ventral striatum suggest problems in decision-making and response planning, and in processing reinforcement cues, respectively. These processes, and their integration, are essential for flexible behavior. Alterations in these systems may therefore contribute to a rigid adherence to preferred behavioral patterns in individuals with an ASD. These findings provide an additional impetus for the use of reversal learning paradigms as a translational model for treatment development targeting the domain of restricted and repetitive behaviors in ASD. PMID:27727243

  6. High performance flexible pH sensor based on carboxyl-functionalized and DEP aligned SWNTs

    Science.gov (United States)

    Liu, Lu; Shao, Jinyou; Li, Xiangming; Zhao, Qiang; Nie, Bangbang; Xu, Chuan; Ding, Haitao

    2016-11-01

    The detection and control of the pH is very important in many biomedical and chemical reaction processes. A miniaturized flexible pH sensor that is light weight, robust, and conformable is very important in many applications, such as multifunctional lab-on-a-chip systems or wearable biomedical devices. In this work, we demonstrate a flexible chemiresistive pH sensor based on dielectrophoresis (DEP) aligned carboxyl-functionalized single-walled carbon nanotubes (SWNTs). Decorated carboxyl groups can react with hydrogen (H+) and hydroxide (OH-) ions, enabling the sensor to be capable of sensing the pH. DEP is used to deposit well-organized and highly aligned SWNTs in desired locations, which improves the metal-nanotube interface and highly rapid detection of the pH, resulting in better overall device performance. When pH buffer solutions are dropped onto such SWNTs, the H+ and OH- ions caninteract with the carboxyl groups and affect the generation of holes and electrons in the SWNTs, leading to resistance variations in the SWNTs. The results shows that the relative resistance variations of the sensor increases linearly with increasing the pH values in the range from 5 to 9 and the response time ranges from 0.2 s to 22.6 s. The pH sensor also shows high performance in mechanical bendability, which benefited from the combination of flexible PET substrates and SWNTs. The SWNT-based flexible pH sensor demonstrates great potential in a wide range of areas due to its simple structure, excellent performance, low power consumption, and compatibility with integrated circuits.

  7. Aggregatibacter aphrophilus pacemaker endocarditis: a case report.

    Science.gov (United States)

    Patel, Sahil R; Patel, Nishi H; Borah, Amit; Saltzman, Heath

    2014-12-08

    Aggregatibacter bacteria are a rare cause of endocarditis in adults. They are part of a group of organisms known as HACEK--Haemophilus, Aggregatibacter, Cardiobacter, Eikenella, and Kingella. Among these organisms, several Haemophilus species have been reclassified under the genus Aggregatibacter. Very few cases of Aggregatibacter endocarditis in patients with pacemaker devices have been reported. We present here what we believe to be the first case of Aggregatibacter aphrophilus pacemaker endocarditis. A 62-year-old African American male with a medical history significant for dual-chamber pacemaker placement in 1996 for complete heart block with subsequent lead manipulation in 2007, presented to his primary care doctor with fever, chills, night sweats, fatigue, and ten-pound weight loss over a four-month period. Physical examination revealed a new murmur and jugular venous distension which prompted initiation of antibiotics for suspicion of endocarditis. Both sets of initial blood cultures were positive for A. aphrophilus. Transesophageal echocardiogram revealed vegetations on the tricuspid valve and the right ventricular pacemaker lead (Figure 1). This case highlights the importance of identifying rare causes of endocarditis and recognizing that treatment may not differ from the standard treatment for typical presentations. The patient received intravenous ceftriaxone for his endocarditis for a total of six weeks. Upon device removal, temporary jugular venous pacing wires were placed. After two weeks of antibiotic treatment and no clinical deterioration, a new permanent pacemaker was placed and the patient was discharged home. This is the first case of A. aphrophilus endocarditis in a patient with a permanent pacemaker. Our patient had no obvious risk factors other than poor dentition and a history of repeated pacemaker lead manipulation. This suggests that valvulopathies secondary to repeated lead manipulation can be clinically significant factors in morbidity

  8. Facile Synthesis of Benzaldehyde-Functionalized Ionic Liquids and Their Flexible Functional Group Transformations

    Directory of Open Access Journals (Sweden)

    Qiang Huang

    2012-01-01

    Full Text Available Three benzaldehyde-functionalized ionic liquids were readily synthesized by quaternization of N-alkylimidazole with benzaldehyde-functionalized alkyl bromides under microwave irradiation in good yield. These aldehyde-functionalized ionic liquids could easily be oxidized in the presence of H2O2/KOH or be reduced by NaBH4 leading to the formation of the corresponding carboxyl-functionalized ionic liquids or benzylic alcohol-functionalized ionic liquids. In addition, the condensations of these functionalized ones with hydrazine hydrate and with aniline under reductive amination conditions were demonstrated.

  9. Single-input/single-output transfer functions for a flexible slewing link

    Science.gov (United States)

    Barbieri, Enrique

    1993-01-01

    Truncated linear models based on constrained and unconstrained mode expansions for a flexible link with torque actuation at its hub led us to examine the behavior of the open-loop-zeros of five commonly used SISO transfer functions. We arrive at new conclusions with regard to minimum- and non-minimum-phase zeros, and passivity of the transfer functions. The flexible-to-rigid inertia (FRI) ratio plays an important role in the determination of these characteristics. This paper illustrates how the zero locations of some of the transfer functions are dramatically affected by the FRI ratio. We also investigate the performance of a hub angle, hub rate, and relative tip position static feedback controller based on a reduced-order constrained mode model when applied to both unconstrained and constrained mode models of the same dimension. Simulations indicate that the constrained model can be stable while the unconstrained model is not for high FRI ratios. Our findings can provide useful information to designers in cases where the controller is sensitive to the 1ocation of the plant's zeros.

  10. Flexible electrochemical biosensors based on O{sub 2} plasma functionalized MWCNT

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun-Yong; Park, Eun-Jin [Department of Biomicrosystem Technology, Korea University, Seoul (Korea, Republic of); Lee, Cheol-Jin; Kim, Soo-Won; Pak, James Jungho [School of Electrical Engineering, Korea University, Seoul (Korea, Republic of); Min, Nam Ki, E-mail: nkmin@korea.ac.k [Department of Control and Instrumentation Engineering, Korea University, Jochiwon (Korea, Republic of)

    2009-05-29

    A flexible glucose sensor is fabricated using O{sub 2} plasma-functionalized multiwalled carbon nanotube (MWCNT) films on polydimethylsiloxane (PDMS) substrates and its performance is electrochemically characterized. After enzyme immobilization, the GOD/ MWCNT/Au/PDMS electrode exhibits a sensitivity of 18.15 {mu}A mm{sup -2}mM{sup -1} and a detection limit of 0.01 mM (signal to noise ratio was about 3). This high sensitivity may be attributed to a large enzyme loading and a higher electrocatalytic activity and electron transfer exhibited by O{sub 2} plasma-functionalized CNTs than the pristine CNT, due to some oxygen-contained groups present on the O{sub 2} plasma-functionalized CNT surface, which has been verified by XPS spectrum.

  11. Analytic Transfer Functions for the Dynamics & Control of Flexible Rotating Spacecraft Performing Large Angle Maneuvers

    Science.gov (United States)

    Elgohary, Tarek A.; Turner, James D.; Junkins, John L.

    2015-06-01

    A symmetric flexible rotating spacecraft can be modeled as a distributed parameter system of a rigid hub attached to two flexible appendages with tip masses. First, Hamilton's extended principle is utilized to establish a general treatment for deriving the dynamics of multi-body dynamical systems to establish a hybrid system of integro-partial differential equations that model the evolution of the system in space and time. A Generalized State Space (GSS) system of equations is constructed in the frequency domain to obtain analytic transfer functions for the rotating spacecraft. This model does not include spatial discretization. The frequency response of the generally modeled spacecraft and a special case with no tip masses are presented. Numerical results for the system frequency response obtained from the analytic transfer functions are presented and compared against the classical assumed modes numerical method with two choices of admissible functions. The truncation-error-free analytic results are used to validate the numerical approximations and to agree well with the classical widely used finite dimensional numerical solutions. Fundamentally, we show that the rigorous transfer function, without introduction of spatial discretization, can be directly used in control law design with a guarantee of Lyapunov stable closed loop dynamics. The frequency response of the system is used in a classical control problem where the Lyapunov stable controller is derived and tested for gain selection. The correlation between the controller design in the frequency domain utilizing the analytic transfer functions and the system response is analyzed and verified. The derived analytic transfer functions provide a powerful tool to test various control schemes in the frequency domain and a validation platform for existing numerical methods for distributed parameters models. The same platform has been used to obtain the frequency response of more complex beam models following

  12. Correlation analysis of the relationship between B-type natriuretic peptide and selected echocardiographic parameters in patients with permanent pacemakers

    Directory of Open Access Journals (Sweden)

    Janusz Sielski

    2016-01-01

    Full Text Available Introduction: The present study was undertaken to evaluate the practical value of BNP measurements and echocardiographic left ventricular volume index in patients with permanent pacemakers because there are no such reports in the literature. Aim of the research: The aim of the study was to reveal multiple correlations between BNP levels and selected echocardiographic parameters of the left atrium in patients with permanent pacemakers. In the literature there are reports on the significance of BNP values and left atrial size in patients with permanent pacemakers. The results of the present study appear to be of value in the outpatient assessment of these patients. Material and methods: We analysed a group of 117 patients with permanent pacemakers (AAI/R 21 patients, DDD/R 59 patients, VVI/R 37 patients and 48 healthy volunteers serving as the control group. BNP measurements were performed on venous blood samples using Triage meters. The Simpson method and the ellipse method were used to assess the left atrium on echocardiography. Results: There was a significant correlation between BNP and maximum left atrial volume, minimum left atrial volume, and left atrial volume index in patients with AAI/R, DDD/R, and VVI/R pacemakers at 3 and 6 months after the implantation. Conclusions : In patients after implantation of permanent pacemakers there are correlations between BNP values and echocardiographic left atrial parameters, especially in patients with DDD/R pacemakers. Left atrial function improves in patients with DDD/R pacemakers. Pacemaker check-up should be extended to include BNP measurements and echocardiographic assessment of the left atrium.

  13. Genetic and phenotypically flexible components of seasonal variation in immune function.

    Science.gov (United States)

    Versteegh, M A; Helm, B; Kleynhans, E J; Gwinner, E; Tieleman, B I

    2014-05-01

    Animals cope with seasonal variation in environmental factors by adjustments of physiology and life history. When seasonal variation is partly predictable, such adjustments can be based on a genetic component or be phenotypically flexible. Animals have to allocate limited resources over different demands, including immune function. Accordingly, immune traits could change seasonally, and such changes could have a genetic component that differs between environments. We tested this hypothesis in genotypically distinct groups of a widespread songbird, the stonechat (Saxicola torquata). We compared variation in immunity during 1 year in long-distance migrants, short-distance migrants, tropical residents and hybrids in a common garden environment. Additionally, we investigated phenotypically flexible responses to temperature by applying different temperature regimes to one group. We assessed constitutive immunity by measuring hemagglutination, hemolysis, haptoglobin and bactericidal ability against Escherichia coli and Staphylococcus aureus. Genotypic groups differed in patterns of variation of all measured immune indices except haptoglobin. Hybrids differed from, but were rarely intermediate to, parental subspecies. Temperature treatment only influenced patterns of hemolysis and bactericidal ability against E. coli. We conclude that seasonal variation in constitutive immunity has a genetic component, that heredity does not follow simple Mendelian rules, and that some immune measures are relatively rigid while others are more flexible. Furthermore, our results support the idea that seasonal variability in constitutive immunity is associated with variability in environment and annual-cycle demands. This study stresses the importance of considering seasonal variation in immune function in relation to the ecology and life history of the organism of interest.

  14. Development of the pacemaker tissues of the heart

    NARCIS (Netherlands)

    Christoffels, V.M.; Smits, G.J.; Kispert, A.; Moorman, A.F.M.

    2010-01-01

    Pacemaker and conduction system myocytes play crucial roles in initiating and regulating the contraction of the cardiac chambers. Genetic defects, acquired diseases, and aging cause dysfunction of the pacemaker and conduction tissues, emphasizing the clinical necessity to understand the molecular

  15. Synchronization of Coupled Neurons Controlled by a Pacemaker

    Institute of Scientific and Technical Information of China (English)

    LI Mei-Sheng; ZHANG Hong-Hui; ZHAO Yong; SHI Xia

    2011-01-01

    We investigate synchronization of Hindmarsh-Rose neurons with gap junctions under the control of a pacemaker. In a ring Hindmarsh-Rose neuronal network, the coupled neurons with the pacemaker can occur in synchronization more easily than those without the pacemaker. Furthermore, the pacemaker can induce phase synchronization or nearly-complete synchronization of nonidentical neurons. This synchronization can occur more easily when time delay is considered. Theses results can be helpful to understand the activities of the real neuronal system.

  16. The pacemaker-twiddler's syndrome: an infrequent cause of pacemaker failure.

    Science.gov (United States)

    Salahuddin, Mohammad; Cader, Fathima Aaysha; Nasrin, Sahela; Chowdhury, Mashhud Zia

    2016-01-20

    The pacemaker-twiddler's syndrome is an uncommon cause of pacemaker malfunction. It occurs due to unintentional or deliberate manipulation of the pacemaker pulse generator within its skin pocket by the patient. This causes coiling of the lead and its dislodgement, resulting in failure of ventricular pacing. More commonly reported among elderly females with impaired cognition, the phenomenon usually occurs in the first year following pacemaker implantation. Treatment involves repositioning of the dislodged leads and suture fixation of the lead and pulse generator within its pocket. An 87 year old Bangladeshi lady who underwent a single chamber ventricular pacemaker (VVI mode: i.e. ventricle paced, ventricle sensed, inhibitory mode) implantation with the indication of complete heart block, and presented to us again 7 weeks later, with syncopal attacks. She admitted to repeatedly manipulating the pacemaker generator in her left pectoral region. Physical examination revealed a heart rate of 42 beats/minute, blood pressure 140/80 mmHg and bilateral crackles on lung auscultation. She had no cognitive deficit. An immediate electrocardiogram showed complete heart block with pacemaker spikes and failure to capture. Chest X-ray showed coiled and retracted right ventricular lead and rotated pulse generator. An emergent temporary pace maker was set at a rate of 60 beats per minute. Subsequently, she underwent successful lead repositioning with strong counselling to avoid further twiddling. Twiddler's syndrome should be considered as a cause of pacemaker failure in elderly patients presenting with bradyarrythmias following pacemaker implantation. Chest X-ray and electrocardiograms are simple and easily-available first line investigations for its diagnosis. Lead repositioning is required, however proper patient education and counselling against further manipulation is paramount to long-term management.

  17. Determination of poles and zeros of transfer functions for flexible spacecraft attitude control

    Science.gov (United States)

    Ohkami, Y.; Likins, P. W.

    1976-01-01

    The transfer function matrix is obtained for a three-input and three-output model of minimum sensors and actuators for the attitude control system of flexible spacecraft, and a method is described for determining the poles and zeros of this transfer function. Three cases are considered: (1) the actuators and the sensors are all attached to the primary body, (2) the actuators are on the primary body and the sensors are on the sub-body, and (3) the actuators are on the sub-body and the sensors are on the primary body. The zero-determination problem is shown to reduce to eigenvalue calculations of a matrix which is constructed from the inertial and modal matrices in a simple fashion.

  18. 21 CFR 870.1750 - External programmable pacemaker pulse generator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External programmable pacemaker pulse generator... External programmable pacemaker pulse generator. (a) Identification. An external programmable pacemaker pulse generators is a device that can be programmed to produce one or more pulses at...

  19. 21 CFR 870.3610 - Implantable pacemaker pulse generator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Implantable pacemaker pulse generator. 870.3610... pacemaker pulse generator. (a) Identification. An implantable pacemaker pulse generator is a device that has a power supply and electronic circuits that produce a periodic electrical pulse to stimulate...

  20. 21 CFR 870.3600 - External pacemaker pulse generator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External pacemaker pulse generator. 870.3600... pacemaker pulse generator. (a) Identification. An external pacemaker pulse generator is a device that has a power supply and electronic circuits that produce a periodic electrical pulse to stimulate the...

  1. 21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended to...

  2. 21 CFR 870.3710 - Pacemaker repair or replacement material.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker repair or replacement material. 870.3710... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3710 Pacemaker repair or replacement material. (a) Identification. A pacemaker repair or replacement material is an...

  3. 21 CFR 870.3650 - Pacemaker polymeric mesh bag.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

  4. 21 CFR 870.3690 - Pacemaker test magnet.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker test magnet. 870.3690 Section 870.3690...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3690 Pacemaker test magnet. (a) Identification. A pacemaker test magnet is a device used to test an inhibited or triggered type...

  5. 21 CFR 870.3730 - Pacemaker service tools.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker service tools. 870.3730 Section 870.3730...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and Allen wrenches...

  6. Uniform pacemaker and ICD information system in the Netherlands

    NARCIS (Netherlands)

    Hooijschuur, CAM; Dijk, WA; van der Velde, W; Sanon, B; Ammeraal, C; Dassen, WRM; Spruijt, HJ; Murray, A

    2002-01-01

    In the Netherlands the Central Pacemaker Patient Registry (CPPR) collects information of pacemaker and ICD (Implantable Cardio Defibrillator) patients from all 109 Dutch hospitals. Many pacemaker clinics are using a computer to store their implant and follow-up data in a database. Because the device

  7. Relationships between mitochondrial function and metabolic flexibility in type 2 diabetes mellitus.

    Directory of Open Access Journals (Sweden)

    Tineke van de Weijer

    Full Text Available INTRODUCTION: Mitochondrial dysfunction, lipid accumulation, insulin resistance and metabolic inflexibility have been implicated in the etiology of type 2 diabetes (T2D, yet their interrelationship remains speculative. We investigated these interrelationships in a group of T2D and obese normoglycemic control subjects. METHODS: 49 non-insulin dependent male T2D patients and 54 male control subjects were enrolled, and a hyperinsulinemic-euglycemic clamp and indirect calorimetry were performed. A muscle biopsy was taken and intramyocellular lipid (IMCL was measured. In vivo mitochondrial function was measured by PCr recovery in 30 T2D patients and 31 control subjects. RESULTS: Fasting NEFA levels were significantly elevated in T2D patients compared with controls, but IMCL was not different. Mitochondrial function in T2D patients was compromised by 12.5% (p<0.01. Whole body glucose disposal (WGD was higher at baseline and lower after insulin stimulation. Metabolic flexibility (ΔRER was lower in the type 2 diabetic patients (0.050±0.033 vs. 0.093±0.050, p<0.01. Mitochondrial function was the sole predictor of basal respiratory exchange ratio (RER (R(2 = 0.18, p<0.05; whereas WGD predicted both insulin-stimulated RER (R(2 = 0.29, p<0.001 and metabolic flexibility (R(2 = 0.40, p<0.001. CONCLUSIONS: These results indicate that defects in skeletal muscle in vivo mitochondrial function in type 2 diabetic patients are only reflected in basal substrate oxidation and highlight the importance of glucose disposal rate as a determinant of substrate utilization in response to insulin.

  8. Prefrontal dopamine and behavioral flexibility: shifting from an inverted-U towards a family of functions

    Directory of Open Access Journals (Sweden)

    Stan B Floresco

    2013-04-01

    Full Text Available Studies on prefrontal cortex (PFC dopamine (DA function have revealed its essential role in mediating a variety of cognitive and executive functions. A general principle that has emerged (primarily from studies on working memory is that PFC DA, acting on D1 receptors, regulates cognition in accordance to an inverted-U shaped function, so that too little or too much activity has detrimental effects on performance. However, contemporary studies have indicated that the receptor mechanisms through which mesocortical DA regulates different aspects of behavioral flexibility can vary considerably across different DA receptors and cognitive operations. This article will review psychopharmacological and neurochemical data comparing and contrasting the cognitive effects of antagonism and stimulation of different DA receptors in the medial PFC. Thus, set-shifting is dependent on a co-operative interaction between PFC D1 and D2 receptors, yet, supranormal stimulation of these receptors does not appear to have detrimental effects on this function. On the other hand, modification of cost/benefit decision biases in situations involving reward uncertainty is regulated in complex and sometimes opposing ways by PFC D1 versus D2 receptors. When viewed collectively, these findings suggest that the inverted-U shaped dose-response curve underlying D1 receptor modulation of working memory is not a one-size-fits-all function. Rather, it appears that mesocortical DA exerts its effects via a family of functions, wherein reduced or excessive DA activity can have a variety of effects across different cognitive domains.

  9. Structural dynamics flexibility informs function and evolution at a proteome scale

    Science.gov (United States)

    Nevin Gerek, Zeynep; Kumar, Sudhir; Banu Ozkan, Sefika

    2013-01-01

    Protein structures are dynamic entities with a myriad of atomic fluctuations, side-chain rotations, and collective domain movements. Although the importance of these dynamics to proper functioning of proteins is emerging in the studies of many protein families, there is a lack of broad evidence for the critical role of protein dynamics in shaping the biological functions of a substantial fraction of residues for a large number of proteins in the human proteome. Here, we propose a novel dynamic flexibility index (dfi) to quantify the dynamic properties of individual residues in any protein and use it to assess the importance of protein dynamics in 100 human proteins. Our analyses involving functionally critical positions, disease-associated and putatively neutral population variations, and the rate of interspecific substitutions per residue produce concordant patterns at a proteome scale. They establish that the preservation of dynamic properties of residues in a protein structure is critical for maintaining the protein/biological function. Therefore, structural dynamics needs to become a major component of the analysis of protein function and evolution. Such analyses will be facilitated by the dfi, which will also enable the integrative use of structural dynamics with evolutionary conservation in genomic medicine as well as functional genomics investigations. PMID:23745135

  10. 双腔心脏起搏器对缓慢性心律失常患者的应用效果及对心功能的影响%Effect of Dual Chamber Pacemaker on Cardiac Function in Patients With Chronic Cardiac Arrhythmia

    Institute of Scientific and Technical Information of China (English)

    张莹

    2016-01-01

    目的:探讨双腔心脏起搏器对缓慢性心律失常患者的应用效果及对心功能的影响。方法选取我院2013年3月~2015年11月收治的67例缓慢性心律失常患者,随机分组,对照组33例,观察组34例,对照组行单腔心脏起搏器植入治疗,观察组行双腔心脏起搏器植入治疗,观察比较两组应用效果及心功能变化情况。结果对照组的有效率为30.30%,观察组为73.53%,组间比较差异有统计学意义(P<0.05);观察组心率、心输出量、心脏指数均高于对照组,差异有统计学意义(P<0.05)。结论双腔心脏起搏器应用于缓慢性心律失常患者,可有效改善患者心功能,提高应用有效率。%Objective To investigate the effect of dual chamber pacemaker on cardiac function in patients with chronic cardiac arrhythmia.Methods 67 patients with chronic arrhythmia were treated in our hospital from March 2013 to November 2015, they were randomly divided into two groups, 33 cases in the control group and 34 cases in the observation group. Patients in the control group were treated with single chamber pacemaker implantation, and the observation group was treated with double chamber pacemaker implantation. We observed and compared the effects of the two groups and the changes of cardiac function. Results The effective rate of control group was 30.30%, the observation group was 73.53%, there was significant difference between the two groups (P<0.05), the heart rate, cardiac output and cardiac index in the observation group were higher than those in the control group, the difference was statistically significant (P<0.05).Conclusion Dual chamber pacemaker used in patients with slow arrhythmia, can effectively improve the patient's cardiac function, improve the efifciency of the application.

  11. Does bipolar pacemaker current activate blood platelets?

    DEFF Research Database (Denmark)

    Gjesdal, Grunde; Hansen, Annebirthe Bo; Brandes, Axel

    2009-01-01

    OBJECTIVE: The aim of this study was to investigate whether bipolar pacemaker current lead can activate blood platelets. The null hypothesis was that 1 minute of electrical stimulation of platelets would not influence their subsequent reactivity to adenosine diphosphate (ADP). BACKGROUND: Both...... platelets and muscle cells contain actin and myosin filaments, and both cells are activated following calcium influx. Muscle cells open their calcium channels and contract when exposed to an electric current. Current through a bipolar pacemaker lead will expose a small volume of blood, including platelets...

  12. Determining a human cardiac pacemaker using fuzzy logic

    Science.gov (United States)

    Varnavsky, A. N.; Antonenco, A. V.

    2017-01-01

    The paper presents a possibility of estimating a human cardiac pacemaker using combined application of nonlinear integral transformation and fuzzy logic, which allows carrying out the analysis in the real-time mode. The system of fuzzy logical conclusion is proposed, membership functions and rules of fuzzy products are defined. It was shown that the ratio of the value of a truth degree of the winning rule condition to the value of a truth degree of any other rule condition is at least 3.

  13. The dynamics of GABA signaling: Revelations from the circadian pacemaker in the suprachiasmatic nucleus.

    Science.gov (United States)

    Albers, H Elliott; Walton, James C; Gamble, Karen L; McNeill, John K; Hummer, Daniel L

    2017-01-01

    Virtually every neuron within the suprachiasmatic nucleus (SCN) communicates via GABAergic signaling. The extracellular levels of GABA within the SCN are determined by a complex interaction of synthesis and transport, as well as synaptic and non-synaptic release. The response to GABA is mediated by GABAA receptors that respond to both phasic and tonic GABA release and that can produce excitatory as well as inhibitory cellular responses. GABA also influences circadian control through the exclusively inhibitory effects of GABAB receptors. Both GABA and neuropeptide signaling occur within the SCN, although the functional consequences of the interactions of these signals are not well understood. This review considers the role of GABA in the circadian pacemaker, in the mechanisms responsible for the generation of circadian rhythms, in the ability of non-photic stimuli to reset the phase of the pacemaker, and in the ability of the day-night cycle to entrain the pacemaker.

  14. Electromagnetic and radiation environments: effects on pacemakers; Environnements electromagnetiques et radiatifs: effets sur les stimulateurs cardiaques

    Energy Technology Data Exchange (ETDEWEB)

    Mouton, J.; Trochet, R.; Vicrey, J.; Sauvage, M. [CEA Bruyeres-le-Chatel, 91 (France); Chauvenet, B.; Ostrovski, A.; Leroy, E. [Bureau National de Metrologie, LPRI, CEA Saclay, 91 - Gif-sur-Yvette (France); Haug, R. [Centre National de la Recherche Scientifique (CNRS), Lab. de Physique des Gaz et des Plasma, SUPELEC, 91 - Orsay (France); Dodinot, B. [Centre de Stimulation Cardiaque, CHU de Brabois, 54 - Vandoeuvre les Nancy (France); Joffre, F. [CEA Saclay, Dept. d' Electronique et d' Instrumentation Nucleaire, LETI, 91 - Gif-sur-Yvette (France)

    1999-07-01

    Nowadays, medical care development allows many people to share the benefits of implanted pacemakers (PM). PM can be perturbed and even fall in complete breakdowns in an electromagnetic and radiation environment. A stimuli-dependent patient can thus be seriously in danger. This article presents the effect of ionizing radiation from either a cobalt-60 source or from a linear accelerator (Saturne 43) on 12 pacemakers. It seems that technological progress make electronic circuits more sensitive to the cumulated dose of radiation. This survey shows that pacemakers have great difficulties to sustain ionizing radiation doses that are commonly delivered to patients during therapies. Usually perturbed functioning appears suddenly and means a strong shift of stimuli that might lead to heart failure.

  15. Pacemaker repetitive nonreentrant ventriculoatrial synchrony. Why did automatic mode switching occur?

    Science.gov (United States)

    Barold, S Serge; Stroobandt, Roland X; Van Heuverswyn, Frederic

    2012-01-01

    Repetitive nonreentrant ventriculoatrial synchrony during dual-chamber pacing is characterized by long intervals alternating with short intervals. This arrangement activated automatic mode switching in a St Jude dual-chamber pacemaker in which the algorithm requires an atrial sensed event for automatic mode switching initiation. Automatic mode switching activation by an atrial sensed event (retrograde P wave) was puzzling because the programmed postventricular atrial period was longer than the retrograde ventriculoatrial conduction time. The explanation is presented in the form of questions and answers to facilitate the understanding of pacemaker function and complex timing cycles.

  16. Electromagnetic interference with a bipolar pacemaker by an induction heating (IH) rice cooker.

    Science.gov (United States)

    Nagatomo, Toshihisa; Abe, Haruhiko; Kohno, Ritsuko; Toyoshima, Takeshi; Fujimoto, Hiroshi; Kondo, Shoichi; Kabashima, Narutoshi; Takeuchi, Masaaki; Tamura, Masahito; Okazaki, Masahiro; Otsuji, Yutaka

    2009-01-01

    Electromagnetic fields may interfere with normal pacemaker function. Despite new device designs and bipolar leads, electromagnetic interference (EMI) remains a concern when pacemaker recipients are exposed to various household appliances. We report the observation of EMI by an induction heating (IH) rice cooker in a patient with sick sinus syndrome who was the recipient of a bipolar dual chamber-pacing system. Stored electrograms revealed episodes of inappropriate ventricular pacing, all coinciding with the opening of an IH rice cooker. Recipients of implantable medical devices must be warned to handle IH rice cookers with caution.

  17. Entirely polytetrafluoroethylene coating for pacemaker system contact dermatitis.

    Science.gov (United States)

    Tamenishi, Akinori; Usui, Akihiko; Oshima, Hideki; Ueda, Yuichi

    2008-04-01

    A 63-year-old man underwent pacemaker implantation for complete atrio-ventricular block. The patient repeated admissions for skin necrosis, and generator or pacemaker system was re-implanted each time. The patient was admitted with skin necrosis of the generator pocket three years after re-implantation. A skin patch test was positive on almost all components of the pacemaker system. The patient underwent pacemaker system removal and re-implantation of polytetrafluoroethylene (PTFE) sheets coating pericardium leads and generator. There has been no recurrence. PTFE sheet coating is effective to treat pacemaker system contact dermatitis.

  18. A flexible multi-reference perturbation theory by minimizing the Hylleraas functional with matrix product states

    CERN Document Server

    Sharma, Sandeep

    2014-01-01

    We describe a formulation of multi-reference perturbation theory that obtains a rigorous upper bound to the second order energy by minimizing the Hylleraas functional in the space of matrix product states (MPS). The first order wavefunctions so obtained can also be used to compute the third order energy with little overhead. Our formulation has several advantages including (i) flexibility with respect to the choice of zeroth order Hamiltonian, (ii) recovery of the exact uncontracted multi-reference perturbation theory energies in the limit of large MPS bond dimension, (iii) no requirement to compute high body density matrices, (iv) an embarrassingly parallel algorithm (scaling up to the number of virtual orbitals, squared, processors). Preliminary numerical examples show that the MPS bond dimension required for accurate first order wavefunctions scales sub-linearly with the size of the basis.

  19. Flexible Two-Dimensional Square-Grid Coordination Polymers: Structures and Functions

    Science.gov (United States)

    Kajiro, Hiroshi; Kondo, Atsushi; Kaneko, Katsumi; Kanoh, Hirofumi

    2010-01-01

    Coordination polymers (CPs) or metal-organic frameworks (MOFs) have attracted considerable attention because of the tunable diversity of structures and functions. A 4,4′-bipyridine molecule, which is a simple, linear, exobidentate, and rigid ligand molecule, can construct two-dimensional (2D) square grid type CPs. Only the 2D-CPs with appropriate metal cations and counter anions exhibit flexibility and adsorb gas with a gate mechanism and these 2D-CPs are called elastic layer-structured metal-organic frameworks (ELMs). Such a unique property can make it possible to overcome the dilemma of strong adsorption and easy desorption, which is one of the ideal properties for practical adsorbents. PMID:21152303

  20. Flexible Two-Dimensional Square-Grid Coordination Polymers: Structures and Functions

    Directory of Open Access Journals (Sweden)

    Hiroshi Kajiro

    2010-09-01

    Full Text Available Coordination polymers (CPs or metal-organic frameworks (MOFs have attracted considerable attention because of the tunable diversity of structures and functions. A 4,4'-bipyridine molecule, which is a simple, linear, exobidentate, and rigid ligand molecule, can construct two-dimensional (2D square grid type CPs. Only the 2D-CPs with appropriate metal cations and counter anions exhibit flexibility and adsorb gas with a gate mechanism and these 2D-CPs are called elastic layer-structured metal-organic frameworks (ELMs. Such a unique property can make it possible to overcome the dilemma of strong adsorption and easy desorption, which is one of the ideal properties for practical adsorbents.

  1. Permanent Leadless Cardiac Pacemaker Therapy: A Comprehensive Review.

    Science.gov (United States)

    Tjong, Fleur V Y; Reddy, Vivek Y

    2017-04-11

    A new technology, leadless pacemaker therapy, was recently introduced clinically to address lead- and pocket-related complications in conventional transvenous pacemaker therapy. These leadless devices are self-contained right ventricular single-chamber pacemakers implanted by using a femoral percutaneous approach. In this review of available clinical data on leadless pacemakers, early results with leadless devices are compared with historical results with conventional single-chamber pacing. Both presently manufactured leadless pacemakers show similar complications, which are mostly related to the implant procedure: cardiac perforation, device dislocation, and femoral vascular access site complications. In comparison with conventional transvenous single-chamber pacemakers, slightly higher short-term complication rates have been observed: 4.8% for leadless pacemakers versus 4.1% for conventional pacemakers. The complication rate of the leadless pacemakers is influenced by the implanter learning curve for this new procedure. No long-term outcome data are yet available for the leadless pacemakers. Larger leadless pacing trials, with long-term follow-up and direct randomized comparison with conventional pacing systems, will be required to define the proper clinical role of these leadless systems. Although current leadless pacemakers are limited to right ventricular pacing, future advanced, communicating, multicomponent systems are expected to expand the potential benefits of leadless therapy to a larger patient population. © 2017 American Heart Association, Inc.

  2. Retrieval of the Leadless Cardiac Pacemaker: A Multicenter Experience.

    Science.gov (United States)

    Reddy, Vivek Y; Miller, Marc A; Knops, Reinoud E; Neuzil, Petr; Defaye, Pascal; Jung, Werner; Doshi, Rahul; Castellani, Mark; Strickberger, Adam; Mead, R Hardwin; Doppalapudi, Harish; Lakkireddy, Dhanunjaya; Bennett, Matthew; Sperzel, Johannes

    2016-12-01

    Leadless cardiac pacemakers have emerged as a safe and effective alternative to conventional transvenous single-chamber ventricular pacemakers. Herein, we report a multicenter experience on the feasibility and safety of acute retrieval (6 weeks) of the leadless cardiac pacemaker in humans. This study included patients enrolled in 3 multicenter trials, who received a leadless cardiac pacemaker implant and who subsequently underwent a device removal attempt. The overall leadless pacemaker retrieval success rate was 94%: for patients whose leadless cardiac pacemaker had been implanted for 6 months before the retrieval attempt. There were no procedure-related adverse events at 30 days post retrieval procedure. This multicenter experience demonstrated the feasibility and safety of retrieving a chronically implanted single-chamber (right ventricle) active fixation leadless pacemaker. URL: https://www.clinicaltrials.gov. Unique identifiers: NCT02051972, NCT02030418, and NCT01700244. © 2016 American Heart Association, Inc.

  3. Intrapericardial pacemaker in a 2-kilogram newborn.

    Science.gov (United States)

    Gil-Jaurena, Juan-Miguel; Castillo, Rafael; Rubio, Lorena

    2012-08-01

    A 2-kilogram child had a pacemaker implanted by a subxyphoid approach with the generator located under the rectus sheath. Days later, the battery eroded the abdominal wall and the peritoneum. The whole system was removed and a new one was implanted inside the pericardium on an emergent basis.

  4. Quality assessment of pacemaker implantations in Denmark

    DEFF Research Database (Denmark)

    Møller, M; Arnsbo, P; Asklund, Mogens

    2002-01-01

    AIMS: Quality assessment of therapeutic procedures is essential to insure a cost-effective health care system. Pacemaker implantation is a common procedure with more than 500,000 implantations world-wide per year, but the general complication rate is not well described. We studied procedure related...

  5. Low atrial septum pacing in pacemaker patients

    NARCIS (Netherlands)

    Voogt, Willem Gijsbert de

    2006-01-01

    In patients with an indication for anti bradycardia pacing, atrial fibrillation (AF) is a common arrhythmia (30-50%) even in the absence of atrial tachy arrhythmias before pacemaker implantation. Pace prevention and pace intervention for atrial tachy arrhythmias could be an interesting adjuvant trea

  6. Low atrial septum pacing in pacemaker patients

    NARCIS (Netherlands)

    Voogt, Willem Gijsbert de

    2006-01-01

    In patients with an indication for anti bradycardia pacing, atrial fibrillation (AF) is a common arrhythmia (30-50%) even in the absence of atrial tachy arrhythmias before pacemaker implantation. Pace prevention and pace intervention for atrial tachy arrhythmias could be an interesting adjuvant

  7. [Cardiac Pacemakers, implantable defibrillators and IRM].

    Science.gov (United States)

    Frank, R; Hidden-Lucet, F; Himbert, C; Petitot, J C; Fontaine, G

    2003-04-01

    The IRM is formally contraindicated to the pacemaker and cardiac defibrillator wearers because of the risk of inhibition or inappropriate stimulations during the examination. However if the examination is essential, suitable programming of the apparatus and a constant monitoring of the heartbeat rate by a qualified doctor in cardiac stimulation must make it possible to avoid any accident.

  8. Prevention of pacemaker-associated contact dermatitis by polytetrafluoroethylene sheet and conduit coating of the pacemaker system.

    Science.gov (United States)

    Taguchi, Takahiro; Maeba, Satoru; Sueda, Taijiro

    2014-09-01

    A 73-year-old female with sick sinus syndrome and atrial fibrillation was implanted with a ventricular demand inhibit pacemaker. She subsequently developed multiple episodes of skin irritation and necrosis. Skin patch testing revealed sensitivity to almost every component of the pacemaker system. The pacemaker was removed and replaced with a new pacemaker in which the generator was covered with a polytetrafluoroethylene (PTFE) sheet and the lead was covered with PTFE conduit. The patient suffered no further episodes of pacemaker-associated contact dermatitis.

  9. Pacemaker stimulus amplitude alteration without loss of capture: an unusual ECG finding in cardiac tamponade from pacemaker lead perforation.

    Science.gov (United States)

    Suksaranjit, P; Prasidthrathsint, K

    2014-01-01

    A variation in pacemaker stimulus amplitude can represent pacemaker system dysfunction from generator malfunction, lead insulation defect, lead fracture, or artefact of digital signal processing of the electrocardiography recorder. Pacemaker lead perforation into the pericardial space typically results in loss of capture which was not demonstrated in our patient. In summary, we report an unusual ECG finding of pacemaker stimulus amplitude alteration without loss of capture in the setting of cardiac tamponade from pacemaker lead perforation. Copyright © 2013 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  10. State-dependent variability of dynamic functional connectivity between frontoparietal and default networks relates to cognitive flexibility.

    Science.gov (United States)

    Douw, Linda; Wakeman, Daniel G; Tanaka, Naoaki; Liu, Hesheng; Stufflebeam, Steven M

    2016-12-17

    The brain is a dynamic, flexible network that continuously reconfigures. However, the neural underpinnings of how state-dependent variability of dynamic functional connectivity (vdFC) relates to cognitive flexibility are unclear. We therefore investigated flexible functional connectivity during resting-state and task-state functional magnetic resonance imaging (rs-fMRI and t-fMRI, resp.) and performed separate, out-of-scanner neuropsychological testing. We hypothesize that state-dependent vdFC between the frontoparietal network (FPN) and the default mode network (DMN) relates to cognitive flexibility. Seventeen healthy subjects performed the Stroop color word test and underwent t-fMRI (Stroop computerized version) and rs-fMRI. Time series were extracted from a cortical atlas, and a sliding window approach was used to obtain a number of correlation matrices per subject. vdFC was defined as the standard deviation of connectivity strengths over these windows. Higher task-state FPN-DMN vdFC was associated with greater out-of-scanner cognitive flexibility, while the opposite relationship was present for resting-state FPN-DMN vdFC. Moreover, greater contrast between task-state and resting-state vdFC related to better cognitive performance. In conclusion, our results suggest that not only the dynamics of connectivity between these networks is seminal for optimal functioning, but also that the contrast between dynamics across states reflects cognitive performance.

  11. Flexible parametric modelling of the cause-specific cumulative incidence function.

    Science.gov (United States)

    Lambert, Paul C; Wilkes, Sally R; Crowther, Michael J

    2016-12-22

    Competing risks arise with time-to-event data when individuals are at risk of more than one type of event and the occurrence of one event precludes the occurrence of all other events. A useful measure with competing risks is the cause-specific cumulative incidence function (CIF), which gives the probability of experiencing a particular event as a function of follow-up time, accounting for the fact that some individuals may have a competing event. When modelling the cause-specific CIF, the most common model is a semi-parametric proportional subhazards model. In this paper, we propose the use of flexible parametric survival models to directly model the cause-specific CIF where the effect of follow-up time is modelled using restricted cubic splines. The models provide smooth estimates of the cause-specific CIF with the important advantage that the approach is easily extended to model time-dependent effects. The models can be fitted using standard survival analysis tools by a combination of data expansion and introducing time-dependent weights. Various link functions are available that allow modelling on different scales and have proportional subhazards, proportional odds and relative absolute risks as particular cases. We conduct a simulation study to evaluate how well the spline functions approximate subhazard functions with complex shapes. The methods are illustrated using data from the European Blood and Marrow Transplantation Registry showing excellent agreement between parametric estimates of the cause-specific CIF and those obtained from a semi-parametric model. We also fit models relaxing the proportional subhazards assumption using alternative link functions and/or including time-dependent effects. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Algorithms for Efficient Computation of Transfer Functions for Large Order Flexible Systems

    Science.gov (United States)

    Maghami, Peiman G.; Giesy, Daniel P.

    1998-01-01

    An efficient and robust computational scheme is given for the calculation of the frequency response function of a large order, flexible system implemented with a linear, time invariant control system. Advantage is taken of the highly structured sparsity of the system matrix of the plant based on a model of the structure using normal mode coordinates. The computational time per frequency point of the new computational scheme is a linear function of system size, a significant improvement over traditional, still-matrix techniques whose computational times per frequency point range from quadratic to cubic functions of system size. This permits the practical frequency domain analysis of systems of much larger order than by traditional, full-matrix techniques. Formulations are given for both open- and closed-loop systems. Numerical examples are presented showing the advantages of the present formulation over traditional approaches, both in speed and in accuracy. Using a model with 703 structural modes, the present method was up to two orders of magnitude faster than a traditional method. The present method generally showed good to excellent accuracy throughout the range of test frequencies, while traditional methods gave adequate accuracy for lower frequencies, but generally deteriorated in performance at higher frequencies with worst case errors being many orders of magnitude times the correct values.

  13. Automatic management of atrial and ventricular stimulation in a contemporary unselected population of pacemaker recipients: the ESSENTIAL Registry.

    Science.gov (United States)

    Biffi, Mauro; Bertini, Matteo; Saporito, Davide; Belotti, Giuseppina; Quartieri, Fabio; Piancastelli, Maurizio; Pucci, Angelo; Boggian, Giulio; Mazzocca, Gian Franco; Giorgi, Davide; Diotallevi, Paolo; Diemberger, Igor; Martignani, Cristian; Pancaldi, Stefano; Ziacchi, Matteo; Marcantoni, Lina; Toselli, Tiziano; Attala, Simone; Iori, Matteo; Bottoni, Nicola; Argnani, Selina; Tomasi, Corrado; Sassone, Biagio; Boriani, Giuseppe

    2016-10-01

    We investigated the applicability of the Ventricular Capture Control (VCC) and Atrial Capture Control (ACC) algorithms for automatic management of cardiac stimulation featured by Biotronik pacemakers in a broad, unselected population of pacemaker recipients. Ventricular Capture Control and Atrial Capture Control were programmed to work at a maximum adapted output voltage as 4.8 V in consecutive recipients of Biotronik pacemakers. Ambulatory threshold measurements were made 1 and 12 months after pacemaker implant/replacement in all possible pacing/sensing configurations, and were compared with manual measurements. Among 542 patients aged 80 (73-85) years, 382 had a pacemaker implant and 160 a pacemaker replacement. Ventricular Capture Control could work at long term in 97% of patients irrespectively of pacing indication, lead type, and lead service life, performance being superior with discordant pacing/sensing configurations. Atrial Capture Control could work in 93% of patients at 4.8 V maximum adapted voltage and at any pulse width, regardless of pacing indication, lead type, and service life. At 12-month follow-up, a ventricular threshold increase ≥1.5 V had occurred in 4.4% of patients uneventfully owing to VCC functioning. Projected pacemaker longevity at 1 month was strongly correlated with the 12-month estimate, and exceeded 13 years in >60% of patients. These algorithms for automatic management of pacing output ensure patient safety in the event of a huge increase of pacing threshold, while enabling maximization of battery longevity. Their applicability is quite broad in an unselected pacemaker population irrespectively of lead choice and service of life. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

  14. Measuring pacemaker dose: A clinical perspective

    Energy Technology Data Exchange (ETDEWEB)

    Studenski, Matthew T., E-mail: matthew.studenski@jeffersonhospital.org [Department of Radiation Oncology at the Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA (United States); Xiao Ying; Harrison, Amy S. [Department of Radiation Oncology at the Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA (United States)

    2012-07-01

    Recently in our clinic, we have seen an increased number of patients presenting with pacemakers and defibrillators. Precautions are taken to develop a treatment plan that minimizes the dose to the pacemaker because of the adverse effects of radiation on the electronics. Here we analyze different dosimeters to determine which is the most accurate in measuring pacemaker or defibrillator dose while at the same time not requiring a significant investment in time to maintain an efficient workflow in the clinic. The dosimeters analyzed here were ion chambers, diodes, metal-oxide-semiconductor field effect transistor (MOSFETs), and optically stimulated luminescence (OSL) dosimeters. A simple phantom was used to quantify the angular and energy dependence of each dosimeter. Next, 8 patients plans were delivered to a Rando phantom with all the dosimeters located where the pacemaker would be, and the measurements were compared with the predicted dose. A cone beam computed tomography (CBCT) image was obtained to determine the dosimeter response in the kilovoltage energy range. In terms of the angular and energy dependence of the dosimeters, the ion chamber and diode were the most stable. For the clinical cases, all the dosimeters match relatively well with the predicted dose, although the ideal dosimeter to use is case dependent. The dosimeters, especially the MOSFETS, tend to be less accurate for the plans, with many lateral beams. Because of their efficiency, we recommend using a MOSFET or a diode to measure the dose. If a discrepancy is observed between the measured and expected dose (especially when the pacemaker to field edge is <10 cm), we recommend analyzing the treatment plan to see whether there are many lateral beams. Follow-up with another dosimeter rather than repeating multiple times with the same type of dosimeter. All dosimeters should be placed after the CBCT has been acquired.

  15. The relationship between multiple joint flexibility and functional performance in independent and physically active elderly women

    Directory of Open Access Journals (Sweden)

    Maria Joana de Carvalho

    2007-09-01

    Full Text Available Multi-joint flexibility assessment seems to be more appropriate for analyzing the association between fl exibility and functional fitness, but there is a lack of studies to confi rm this possibility in elderly people. The present study investigated the relationship between a multiple joint fl exibility assessment and the functional performance of 30 independent and physically active elderly women (age=68±1yr. Flexibility was assessed using the Chair Sit-and-Reach Test (CSRT. Functional performance was tested by a combination of three tasks: a Step Length (SL; b Time to Put on Sneakers (TPS; c Climbing Stairs (CS. The association between fl exibility and functional performance was tested by both simple and multiple correlation techniques. Pearson’s correlation was signifi cant for TPS (r = -.37; p ABSTRACT

  16. Diffusion as a function of guest molecule length and functionalization in flexible metal–organic frameworks

    KAUST Repository

    Zheng, B.

    2016-05-11

    Understanding guest diffusion in nanoporous host-guest systems is crucial in the efficient design of metal-organic frameworks (MOFs) for chemical separation and drug delivery applications. In this work, we investigated the effect of molecule length on the diffusion rate in the zeolitic imidazolate framework 8 (ZIF-8), trying to find a simple and straightforward variable to characterize the complicated guest diffusion. We found that, counter-intuitively, long guest molecules can diffuse as quickly as short molecules; the diffusion coefficient of ethyl acetate for example is of the same order of magnitude as ethane and ethanol, as excludes the existence of a simple relationship between molecule length and diffusion rate. This phenomenon is explained by a study of the contributions of intra- and inter-cage movement to overall transport. Steric confinement limits the degrees of freedom of long guest molecules, shortening their residence time and increasing the efficiency of radial diffusion. In contrast, shorter molecules meander within MOF cages, reducing transport. Furthermore, the energy barrier of inter-cage transport also does not exhibit a simple dependence on a guest molecule length, attributing to the effect of the type of functional group on diffusion. Guests over varying lengths were investigated by using theoretical methods, revealing that the guest diffusion in ZIF-8 depends on the number of contiguous carbon atoms in a molecule, rather than its overall length. Thus, we proposed simple criteria to predict arbitrary guest molecule diffusivity in ZIF-8 without time-consuming experimentation. © 2016 The Royal Society of Chemistry.

  17. Excitation model of pacemaker cardiomyocytes of cardiac conduction system

    Science.gov (United States)

    Grigoriev, M.; Babich, L.

    2015-11-01

    Myocardium includes typical and atypical cardiomyocytes - pacemakers, which form the cardiac conduction system. Excitation from the atrioventricular node in normal conditions is possible only in one direction. Retrograde direction of pulses is impossible. The most important prerequisite for the work of cardiomyocytes is the anatomical integrity of the conduction system. Changes in contractile force of the cardiomyocytes, which appear periodically, are due to two mechanisms of self-regulation - heterometric and homeometric. Graphic course of the excitation pulse propagation along the heart muscle more accurately reveals the understanding of the arrhythmia mechanism. These models have the ability to visualize the essence of excitation dynamics. However, they do not have the proper forecasting function for result estimation. Integrative mathematical model enables further investigation of general laws of the myocardium active behavior, allows for determination of the violation mechanism of electrical and contractile function of cardiomyocytes. Currently, there is no full understanding of the topography of pacemakers and ionic mechanisms. There is a need for the development of direction of mathematical modeling and comparative studies of the electrophysiological arrangement of cells of atrioventricular connection and ventricular conduction system.

  18. Template-mediated synthesis and bio-functionalization of flexible lignin-based nanotubes and nanowires

    Science.gov (United States)

    Caicedo, Hector M.; Dempere, Luisa A.; Vermerris, Wilfred

    2012-03-01

    Limitations of cylindrical carbon nanotubes based on the buckminsterfullerene structure as delivery vehicles for therapeutic agents include their chemical inertness, sharp edges and toxicological concerns. As an alternative, we have developed lignin-based nanotubes synthesized in a sacrificial template of commercially available alumina membranes. Lignin is a complex phenolic plant cell wall polymer that is generated as a waste product from paper mills and biorefineries that process lignocellulosic biomass into fuels and chemicals. We covalently linked isolated lignin to the inner walls of activated alumina membranes and then added layers of dehydrogenation polymer onto this base layer via a peroxidase-catalyzed reaction. By using phenolic monomers displaying different reactivities, we were able to change the thickness of the polymer layer deposited within the pores, resulting in the synthesis of nanotubes with a wall thickness of approximately 15 nm or nanowires with a nominal diameter of 200 nm. These novel nanotubes are flexible and can be bio-functionalized easily and specifically, as shown by in vitro assays with biotin and Concanavalin A. Together with their intrinsic optical properties, which can also be varied as a function of their chemical composition, these lignin-based nanotubes are expected to enable a variety of new applications including as delivery systems that can be easily localized and imaged after uptake by living cells.

  19. Magnetic Resonance Imaging in Nondependent Pacemaker Patients with Pacemakers and Defibrillators with a Nearly Depleted Battery.

    Science.gov (United States)

    Okamura, Hideo; Padmanabhan, Deepak; Watson, Robert E; Dalzell, Connie; Acker, Nancy; Jondal, Mary; Romme, Abby L; Cha, Yong-Mei; Asirvatham, Samuel J; Felmlee, Joel P; Friedman, Paul A

    2017-05-01

    Magnetic resonance imaging (MRI) in patients with non-MRI-conditional cardiac implantable electronic devices (CIEDs) has been shown to be safe when performed under closely monitored protocols. However, the safety of MRI in patients with devices with a nearly depleted battery has not been reported. Prospective data were collected between January 2008 and May 2015 in patients with non-MRI-conditional CIEDs undergoing clinically indicated MRI under institutional protocol. Patients who were pacemaker dependent were excluded. Patients whose devices were at elective replacement indicator (ERI) at the time of MRI or close to ERI (ERI or replacement for battery depletion within 3 months of scan) were identified through database review and analyzed for clinical events. MRI scans (n = 569) were performed in 442 patients. Of these, we identified 13 scans performed with a nearly depleted battery in nine patients. All scans with implantable cardioverter defibrillators (ICDs, n = 9) were uneventful. However, two scans with pacemakers close to ERI resulted in a power-on-reset (PoR) event. One scan with a pacemaker close to ERI that was programmed to DOO mode reached ERI during MRI and automatically changed to VVI mode. Additionally, one scan with a pacemaker at ERI did not allow programming. All pacemakers with events were implanted before 2005. Patients with pacemakers and ICDs with a nearly depleted battery can safely undergo MRI when patients are not pacemaker dependent. Attention should be paid because old devices can result in PoR or ERI during MRI, which may lead to oversensing and inhibition of pacing. © 2017 Wiley Periodicals, Inc.

  20. Reduction of atrial fibrillation in remotely monitored pacemaker patients: results from a Chinese multicentre registry

    Institute of Scientific and Technical Information of China (English)

    CHEN Ke-ping; DAI Yan; HUA Wei; YANG Jie-fu; LI Kang; LIANG Zhao-guang; SHEN Fa-rong

    2013-01-01

    Background Many recipients of implantable cardiac electronic devices have atrial fibrillation (AF) occurrences after device implantation,even if there is no previous history of AF,and some of the episodes are asymptomatic.The purpose of this study was to evaluate trends in AF burden following early AF detection in patients treated with pacemakers equipped with automatic,daily Home Monitoring function.Methods Between February 2009 and December 2010,the registry recruited 701 pacemaker patients (628 dual-chamber,73 biventricular devices) at 97 clinical centers in China.Daily Home Monitoring data transmissions were analyzed to screen for the AF burden.In-office follow-ups were scheduled for 3 and 6 months after implantation.Upon first AF (i.e.,mode-switch) detection in a patient,screening of AF burden by Home Monitoring was extended for the next 180 days.Results At least one episode of AF was observed in 22.9% of patients with dual-chamber pacemakers and in 28.8% of patients with biventricular pacemakers.The first AF detection in a patient occurred,on average,about 2 months before scheduled follow-up visits.In both pacemaker groups,mean AF burden decreased significantly (P<0.05) over 180 days following first AF detection:from 12.0% to 2.5% in dual-chamber and from 12.2% to 0.5% in biventricular pacemaker recipients.The number of patients with an AF burden >10% per month was significantly reduced over 6 months of implantation in both dual chamber (38 patients in the first month vs.21 patients in month 6,P<0.05) and biventricular (7 patients in the first month vs.0 patient in months 4-6,P<0.05) pacemaker recipients.Conclusions Automatic,daily Home Monitoring of patients treated with cardiac pacemakers allows early detection of AF,and there is a gradual and significant decrease in AF burden.

  1. Popeye domain containing proteins are essential for stress-mediated modulation of cardiac pacemaking in mice.

    Science.gov (United States)

    Froese, Alexander; Breher, Stephanie S; Waldeyer, Christoph; Schindler, Roland F R; Nikolaev, Viacheslav O; Rinné, Susanne; Wischmeyer, Erhard; Schlueter, Jan; Becher, Jan; Simrick, Subreena; Vauti, Franz; Kuhtz, Juliane; Meister, Patrick; Kreissl, Sonja; Torlopp, Angela; Liebig, Sonja K; Laakmann, Sandra; Müller, Thomas D; Neumann, Joachim; Stieber, Juliane; Ludwig, Andreas; Maier, Sebastian K; Decher, Niels; Arnold, Hans-Henning; Kirchhof, Paulus; Fabritz, Larissa; Brand, Thomas

    2012-03-01

    Cardiac pacemaker cells create rhythmic pulses that control heart rate; pacemaker dysfunction is a prevalent disorder in the elderly, but little is known about the underlying molecular causes. Popeye domain containing (Popdc) genes encode membrane proteins with high expression levels in cardiac myocytes and specifically in the cardiac pacemaking and conduction system. Here, we report the phenotypic analysis of mice deficient in Popdc1 or Popdc2. ECG analysis revealed severe sinus node dysfunction when freely roaming mutant animals were subjected to physical or mental stress. In both mutants, bradyarrhythmia developed in an age-dependent manner. Furthermore, we found that the conserved Popeye domain functioned as a high-affinity cAMP-binding site. Popdc proteins interacted with the potassium channel TREK-1, which led to increased cell surface expression and enhanced current density, both of which were negatively modulated by cAMP. These data indicate that Popdc proteins have an important regulatory function in heart rate dynamics that is mediated, at least in part, through cAMP binding. Mice with mutant Popdc1 and Popdc2 alleles are therefore useful models for the dissection of the mechanisms causing pacemaker dysfunction and could aid in the development of strategies for therapeutic intervention.

  2. Specifying Links between Executive Functioning and Theory of Mind during Middle Childhood: Cognitive Flexibility Predicts Social Understanding

    Science.gov (United States)

    Bock, Allison M.; Gallaway, Kristin C.; Hund, Alycia M.

    2015-01-01

    The purpose of this study was to specify the development of and links between executive functioning and theory of mind during middle childhood. One hundred four 7- to 12-year-old children completed a battery of age-appropriate tasks measuring working memory, inhibition, flexibility, theory of mind, and vocabulary. As expected, spatial working…

  3. Specifying Links between Executive Functioning and Theory of Mind during Middle Childhood: Cognitive Flexibility Predicts Social Understanding

    Science.gov (United States)

    Bock, Allison M.; Gallaway, Kristin C.; Hund, Alycia M.

    2015-01-01

    The purpose of this study was to specify the development of and links between executive functioning and theory of mind during middle childhood. One hundred four 7- to 12-year-old children completed a battery of age-appropriate tasks measuring working memory, inhibition, flexibility, theory of mind, and vocabulary. As expected, spatial working…

  4. Choosing the pacemaker; a rational approach to the use of modern pacemaker technology.

    Science.gov (United States)

    Morgan, J M; Joseph, S P; Bahri, A K; Ramdial, J; Crowther, A

    1990-08-01

    Sophisticated pacemakers now afford greater benefit than only relief of syncope for patients with symptomatic bradyarrhythmia. For clinical reasons it is inappropriate to implant ventricular demand (VVI) pacemakers in every patient, but for both clinical and economic reasons it is also undesirable to use dual-lead or rate-responsive systems indiscriminately. However, the published guidelines for pacemaker choice and investigation are inadequate. We have analysed the clinical assessment and the investigations required in a series of 150 patients with various electrophysiological disorders, considered consecutively for pacemaker implantation using an algorithm to assist decisions. Holter electrocardiography in 77.3%, exercise testing--formal (in 9.3%) or informal (during Holter electrocardiography), electrophysiology study (EPS)--full in 15.3% and partial in 29.3%, and trial of pacing (10.7%) were all used to characterize dysfunction and to define appropriate pacing mode. 142 patients were paced--57.0% with single lead modes (12.7%) AAI, 44.3% VVI) and 43.0% dual-lead (2.8% DVI, 23.9% VDD or VAT, 16.2% DDD). Three patients received rate-responsive systems (VVIR) which, if available, would have been used in nine; four would have been suitable for AAIR and four for dual-lead responsive pacing (DVIR, DDIR or DDDR). We offer a rational approach based on published data for investigation and pacemaker choice in the management of patients with bradyarrhythmia.

  5. Enhanced Flexible Tubular Microelectrode with Conducting Polymer for Multi-Functional Implantable Tissue-Machine Interface

    Science.gov (United States)

    Tian, Hong-Chang; Liu, Jing-Quan; Kang, Xiao-Yang; Tang, Long-Jun; Wang, Ming-Hao; Ji, Bo-Wen; Yang, Bin; Wang, Xiao-Lin; Chen, Xiang; Yang, Chun-Sheng

    2016-05-01

    Implantable biomedical microdevices enable the restoration of body function and improvement of health condition. As the interface between artificial machines and natural tissue, various kinds of microelectrodes with high density and tiny size were developed to undertake precise and complex medical tasks through electrical stimulation and electrophysiological recording. However, if only the electrical interaction existed between electrodes and muscle or nerve tissue without nutrition factor delivery, it would eventually lead to a significant symptom of denervation-induced skeletal muscle atrophy. In this paper, we developed a novel flexible tubular microelectrode integrated with fluidic drug delivery channel for dynamic tissue implant. First, the whole microelectrode was made of biocompatible polymers, which could avoid the drawbacks of the stiff microelectrodes that are easy to be broken and damage tissue. Moreover, the microelectrode sites were circumferentially distributed on the surface of polymer microtube in three dimensions, which would be beneficial to the spatial selectivity. Finally, the in vivo results confirmed that our implantable tubular microelectrodes were suitable for dynamic electrophysiological recording and simultaneous fluidic drug delivery, and the electrode performance was further enhanced by the conducting polymer modification.

  6. Refining Inquiry with Multi-Form Assessment: Formative and summative assessment functions for flexible inquiry

    Science.gov (United States)

    Zuiker, Steven; Reid Whitaker, J.

    2014-04-01

    This paper describes the 5E+I/A inquiry model and reports a case study of one curricular enactment by a US fifth-grade classroom. A literature review establishes the model's conceptual adequacy with respect to longstanding research related to both the 5E inquiry model and multiple, incremental innovations of it. As a collective line of research, the review highlights a common emphasis on formative assessment, at times coupled either with differentiated instruction strategies or with activities that target the generalization of learning. The 5E+I/A model contributes a multi-level assessment strategy that balances formative and summative functions of multiple forms of assessment in order to support classroom participation while still attending to individual achievement. The case report documents the enactment of a weeklong 5E+I/A curricular design as a preliminary account of the model's empirical adequacy. A descriptive and analytical narrative illustrates variable ways that multi-level assessment makes student thinking visible and pedagogical decision-making more powerful. In light of both, it also documents productive adaptations to a flexible curricular design and considers future research to advance this collective line of inquiry.

  7. Design and fabrication of magnetically functionalized flexible micropillar arrays for rapid and controllable microfluidic mixing

    KAUST Repository

    Zhou, BingPu

    2015-03-25

    Magnetically functionalized PDMS-based micropillar arrays have been successfully designed, fabricated and implanted for controllable microfluidic mixing. The arrangement of PDMS micropillar arrays inside the microchannel can be flexibly controlled by an external magnetic field. As a consequence, the flow fields inside the microchannel can be regulated at will via magnetic activation conveniently. When a microchannel is implanted with such micropillar arrays, two microstreams can be mixed easily and controllably upon the simple application of an on/off magnetic signal. Mixing efficiencies based on micropillar arrays with different densities were investigated and compared. It was found that micropillar arrays with higher density (i.e. smaller pillar pitch) would render better mixing performance. Our microfluidic system is capable of generating highly reproducible results within many cycles of mixing/non-mixing conversion. We believe that the simple mixing-triggering method together with rapid and controllable mixing control will be extraordinarily valuable for various biological or chemical applications in the future. This journal is © The Royal Society of Chemistry 2015.

  8. Neutron absorbed dose in a pacemaker CMOS

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Guzman G, K. A.; Valero L, C.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L., E-mail: fermineutron@yahoo.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2012-06-15

    The neutron spectrum and the absorbed dose in a Complementary Metal Oxide Semiconductor (CMOS), has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes an oncology patient that must be treated in a linear accelerator. Pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. Above 7 MV therapeutic beam is contaminated with photoneutrons that could damage the CMOS. Here, the neutron spectrum and the absorbed dose in a CMOS cell was calculated, also the spectra were calculated in two point-like detectors in the room. Neutron spectrum in the CMOS cell shows a small peak between 0.1 to 1 MeV and a larger peak in the thermal region, joined by epithermal neutrons, same features were observed in the point-like detectors. The absorbed dose in the CMOS was 1.522 x 10{sup -17} Gy per neutron emitted by the source. (Author)

  9. Current status of pacemaker power sources.

    Science.gov (United States)

    Tyers, G F; Brownlee, R R

    1978-06-01

    After years during which pacers of very similar design and capabilities were provided by a small number of manufactures, many different lithium, halogen, rechargeable, and nuclear power sources are now available. The variety of chemistries, methods of construction, and sealing techniques used in the batteries of the different manufacturers is almost unlimited. This has made it necessary for physicians who implant and follow pacer to acquire a general knowledge of the field if they are to make an informed choice of pacemaker power source for implantation and if they are to manage recalls with a minimum of patient and physician trauma. More experience is required before it can be definitely determined which of the new pacer power sources will prove superior, but when coupled with well-designed, hermetically sealed pulse generators, all are capable of providing continuous pacing for at least 5 years and the 10-year pacemaker is now a probability.

  10. [Magnets, pacemaker and defibrillator: fatal attraction?].

    Science.gov (United States)

    Bergamin, C; Graf, D

    2015-05-27

    This article aims at clarifying the effects of a clinical magnet on pacemakers and Implantable Cardioverter Defibrillators. The effects of electromagnetic interferences on such devices, including interferences linked to electrosurgery and magnetic resonance imaging are also discussed. In general, a magnet provokes a distinctive effect on a pacemaker by converting it into an asynchronous mode of pacing, and on an Implantable Cardioverter Defibrillator by suspending its own antitachyarythmia therapies without affecting the pacing. In the operating room, the magnet has to be used cautiously with precisely defined protocols which respect the type of the device used, the type of intervention planned, the presence or absence of EMI and the pacing-dependency of the patient.

  11. 76 FR 48058 - Effective Date of Requirement for Premarket Approval for Cardiovascular Permanent Pacemaker...

    Science.gov (United States)

    2011-08-08

    ... Approval for Cardiovascular Permanent Pacemaker Electrode AGENCY: Food and Drug Administration, HHS. ACTION... the following class III preamendments device: Cardiovascular permanent pacemaker electrode. The Agency... permanent pacemaker electrode based on new information. This action implements certain statutory...

  12. Monocenter feasibility study of the MRI compatibility of the Evia pacemaker in combination with Safio S pacemaker lead

    Science.gov (United States)

    2012-01-01

    Background The purpose of this study was to evaluate the feasibility of the magnetic resonance (MR) conditional pacemaker (PM) system (Evia SR-T and DR-T with Safio S leads) under MR conditions. Methods Patients with standard PM indications and Evia PM were eligible for enrollment in this single center prospective non-randomized pilot study. Patients underwent MR of the brain and lower lumbar spine at 1.5 Tesla. Atrial (RA) und ventricular (RV) lead parameters (sensing, pacing threshold [PTH], pacing impedance) were assessed immediately before (baseline follow-up [FU]) and immediately after MRI (1st FU), after 1 month (2nd FU) and 3 months (3rd FU). The effect of MR on serious adverse device effect (SADE) free-rate, on atrial and ventricular sensing (AS/VS; mV) and atrial (RA) and ventricular (RV) pacing thresholds (PTH; V/0.4 ms) were investigated between baseline and 2nd FU. Continuous variables are expressed as mean ± SD and were compared using paired Student’s t-test. A p pacemakers led to MR imaging artifacts on diffusion weighted sequences of the brain, but did not affect other sequences (e.g. FLAIR and T2 weighted spin-echo images). Conclusion The use of the MR conditional Evia PM in a MR environment under predefined conditions is feasible. No MR related SADEs nor clinically relevant changes in device functions occurred. PMID:23009683

  13. The effect of metal detector gates on implanted permanent pacemakers.

    Science.gov (United States)

    Copperman, Y; Zarfati, D; Laniado, S

    1988-10-01

    The effect of metal detector security gates, such as are used in airports, was tested in 103 nonselected pacemaker patients. Various types of single and dual chamber units were examined, using telemetry during the test. Pulse rate and duration were measured immediately before and after the procedure. No ill effect was seen on any of the units tested, pacemaker inhibition was not observed, and programmability was not affected. Metal detector security gates have no effect on implanted permanent pacemakers.

  14. A rare case of recurrent pacemaker allergic reaction

    Directory of Open Access Journals (Sweden)

    Muhammed Shittu

    2015-01-01

    Full Text Available Allergic reactions to pacemaker device components are uncommon. However, when they occur, they usually mimic pacemaker infection, which results in multiple device replacements and increased morbidity burden. Here we present a 40-year-old female with pacemaker insertion due to complete heart block and who had multiple device replacements because of allergic sensitivity to various pacemaker component-encasing materials, confirmed by allergic testing to these materials. She had complete resolution of her symptoms after replacement with gold-plated device, to which she was not allergic.

  15. Effect of resistive training on the maximum strenght,flexibility and functional autonomy of elderly woman

    Directory of Open Access Journals (Sweden)

    Estélio Henrique Martin Dantas

    2006-12-01

    Full Text Available The objective of this study was to investigate the effects of resistive training on maximum strength, flexibility and functional autonomy, as well as the correlation between maximum strength and functional autonomy of the elderly women (strength group, GF, n=11, = 66.3 ± 7.84 years/control group, GC, n=11, =65.1 ± 3.33 years. They participated of a resistive training (75-85% 1RM during 16 weeks, 2 days/week. Statistical procedures were Pearson’s correlation and Student t-test, using the SPSS package, version 12.0. Data showed signifi cant results for GF on the strength, fl exibility and functional autonomy, and signifi cant correlation between strength and functional autonomy (r=-0.67. The data suggested that training program enhances performance in activities of daily living with a training protocol of only 2 days/week. RESUMO O objetivo desse estudo foi verifi car os efeitos do treinamento resistido na força máxima, na fl exibilidade e na autonomia funcional, bem como a correlação existente entre a força máxima e a autonomia funcional de idosas (grupo de força - GF n=11, = 66,3±7,84 anos e um grupo controle - GC n=11, =65,1±3,33 anos. O GF foi submetido a um treinamento contra resistência de força (75-85% 1RM, por 16 semanas, 2 dias/semana. O tratamento estatístico utilizado foi correlação de Pearson e o teste “t” de Student. Os dados mostraram resultados signifi cativos do GF no ganho da força máxima, fl exibilidade e autonomia funcional, e correlação signifi cativa entre a força máxima medida no exercício supino reto (SR e o teste de autonomia funcional levantar da posição de decúbito ventral (LPDV (r=-0,67. Os dados sugerem que o programa de treinamento melhorou o desempenho das atividades da vida diária da amostra, com um treinamento de apenas 2 dias/semana.

  16. Flexible Patterning of Functional Microdot by Laser-Induced Dot Transfer

    National Research Council Canada - National Science Library

    Aiko Narazaki; Ryozo Kurosaki; Tadatake Sato; Hiroyuki Niino

    2014-01-01

      Laser-induced dot transfer (LIDT) is one of promising additive manufacturing techniques because it can realize flexible patterning of micron and submicron-sized dots even at atmospheric room-temperature conditions...

  17. Male and female runners demonstrate different sagittal plane mechanics as a function of static hamstring flexibility

    Directory of Open Access Journals (Sweden)

    D. S. Blaise Williams III

    2015-10-01

    Full Text Available ABSTRACTBackground:Injuries to runners are common. However, there are many potential contributing factors to injury. While lack of flexibility alone is commonly related to injury, there are clear differences in hamstring flexibility between males and females.Objective: To compare the effect of static hamstring length on sagittal plane mechanics between male and female runners.Method: Forty subjects (30.0±6.4 years participated and were placed in one of 4 groups: flexible males (n=10, inflexible males (n=10, flexible females (n=10, and inflexible females (n=10. All subjects were free of injury at the time of data collection. Three-dimensional kinematics and kinetics were collected while subjects ran over ground across 2 force platforms. Sagittal plane joint angles and moments were calculated at the knee and hip and compared with a 2-way (sex X flexibility ANOVA (α=0.05.Results: Males exhibited greater peak knee extension moment than females (M=2.80±0.47, F=2.48±0.52 Nm/kg*m, p=0.05 and inflexible runners exhibited greater peak knee extension moment than flexible runners (In=2.83±0.56, Fl=2.44±0.51 Nm/kg*m, p=0.01. For hip flexion at initial contact, a significant interaction existed (p<0.05. Flexible females (36.7±7.4º exhibited more hip flexion than inflexible females (27.9±4.6º, p<0.01 and flexible males (30.1±9.5º, p<0.05. No differences existed for knee angle at initial contact, peak knee angle, peak hip angle, or peak hip moment.Conclusion: Hamstring flexibility results in different mechanical profiles in males and females. Flexibility in the hamstrings may result in decreased moments via active or passive tension. These differences may have implications for performance and injury in flexible female runners.

  18. Normal heart rhythm is initiated and regulated by an intracellular calcium clock within pacemaker cells.

    Science.gov (United States)

    Maltsev, Victor A; Lakatta, Edward G

    2007-10-01

    For almost half a century it has been thought that the heart rhythm originates on the surface membrane of the cardiac pacemaker cells and is driven by voltage-gated ion channels (membrane clocks). Data from several recent studies, however, conclusively show that the rhythm is initiated, sustained, and regulated by oscillatory Ca(2+) releases (Ca(2+) clock) from the sarcoplasmic reticulum, a major Ca(2+) store within sinoatrial node cells, the primary heart's pacemakers. Activation of the local oscillatory Ca(2+) releases is independent of membrane depolarisation and driven by a high level of basal state phosphorylation of Ca(2+) cycling proteins. The releases produce Ca(2+) wavelets under the cell surface membrane during the later phase of diastolic depolarisation and activate the forward mode of Na(+)/Ca(2+) exchanger resulting in inward membrane current, which ignites an action potential. Phosphorylation-dependent gradation of speed at which Ca(2+) clock cycles is the essential regulatory mechanism of normal pacemaker rate and rhythm. The robust regulation of pacemaker function is insured by tight integration of Ca(2+) and membrane clocks: the action potential shape and ion fluxes are tuned by membrane clocks to sustain operation of the Ca(2+) clock which produces timely and powerful ignition of the membrane clocks to effect action potentials.

  19. Performance of a rate responsive accelerometer-based pacemaker with autocalibration during standardized exercise and recovery.

    Science.gov (United States)

    Garrigue, Stephane; Gentilini, Claudio; Hofgartner, Franz; Mouton, Elisabeth; Rousseau, Anne; Clementy, Jacques

    2002-06-01

    The rate responsiveness of a single chamber, accelerometer-based pacemaker with an autocalibration function (Opus G VVIR pacemaker, ELA Medical) was studied with a daily life protocol developed to automatically optimize the programming of accelerometer-based sensors. This new sensor was compared with two other body activity sensors that were manually optimized patient by patient. Forty-three pacemaker recipients (mean age 71 +/- 11 years), paced > 95% of the time, underwent a daily life protocol consisting of rapid walking for 6 minutes (W), climbing upstairs for 1.5 minutes (U), and downstairs for 1.5 minutes (D), alternated by recovery phases. The results were compared with performances measured in a control population of healthy subjects and in two paced patient populations (one equipped with a Dash Intermedics VVIR pacemaker and the other equipped with a Sensolog III Pacesetter/St. Jude VVIR pacemaker). Sex distribution and mean age between paced patients and control subjects were statistically comparable. The mean heartrate achieved by all paced patients at each time sample was compared with the normograms, assigning acceleration (slope) and rate (rate) scores for exercise and recovery phases. Scores ranged from -10 (hypochronotropic) to +10 (hyperchronotropic). Zero represents exact concordance with the responses of healthy individuals, and values between -2.5 and +2.5 were considered statistically similar to normal. During W, although the overall performances of the Dash, Sensolog, and Opus G did not statistically differ from healthy controls, the scores obtained by the Opus G were significantly closer to controls than those of the two other pacemakers (P = 0.02). For U, the three sensors were hypochronotropic (P = 0.03), though the Opus G was associated with a heart rate response closer to that of healthy controls (P = 0.04). D provided similar mean heart rate scores for the Opus G and the Dash compared with healthy controls, in contrast with the

  20. 76 FR 53851 - Effective Date of Requirement for Premarket Approval for Cardiovascular Permanent Pacemaker...

    Science.gov (United States)

    2011-08-30

    ... Approval for Cardiovascular Permanent Pacemaker Electrode; Correction AGENCY: Food and Drug Administration... development protocol for the class III preamendments device: Cardiovascular permanent pacemaker electrode. The...

  1. Functional ecology of saltglands in shorebirds: Flexible responses to variable environmental conditions

    Science.gov (United States)

    Gutierrez, J.S.; Dietz, M.W.; Masero, J.A.; Gill, R.E.; Dekinga, Anne; Battley, Phil F.; Sanchez-Guzman, J. M.; Piersma, Theunis

    2012-01-01

    Birds of marine environments have specialized glands to excrete salt, the saltglands. Located on the skull between the eyes, the size of these organs is expected to reflect their demand, which will vary with water turnover rates as a function of environmental (heat load, salinity of prey and drinking water) and organismal (energy demand, physiological state) factors. On the basis of inter- and intraspecific comparisons of saltgland mass (m sg) in 29 species of shorebird (suborder Charadrii) from saline, fresh and mixed water habitats, we assessed the relative roles of organism and environment in determining measured m sg species. The allometric exponent, scaling dry m sg to shorebird total body mass (m b), was significantly higher for coastal marine species (0??88, N=19) than for nonmarine species (0??43, N=14). Within the marine species, those ingesting bivalves intact had significantly higher m sg than species eating soft-bodied invertebrates, indicating that seawater contained within the shells added to the salt load. In red knots (Calidris canutus), dry m sg varied with monthly averaged ambient temperature in a U-shaped way, with the lowest mass at 12??5??C. This probably reflects increased energy demand for thermoregulation at low temperatures and elevated respiratory water loss at high temperatures. In fuelling bar-tailed godwits (Limosa lapponica), dry m sg was positively correlated with intestine mass, an indicator of relative food intake rates. These findings suggest once more that saltgland masses vary within species (and presumably individuals) in relation to salt load, that is a function of energy turnover (thermoregulation and fuelling) and evaporative water needs. Our results support the notion that m sg is strongly influenced by habitat salinity, and also by factors influencing salt load and demand for osmotically free water including ambient temperature, prey type and energy intake rates. Saltglands are evidently highly flexible organs. The small

  2. Flexibility and rigidity, requirements for the function of proteins and protein pigment complexes. Eleventh Keilin memorial lecture.

    Science.gov (United States)

    Huber, R

    1987-12-01

    Proteins may be rigid or flexible to various degrees as required for optimum function. Flexibility at the level of amino acid side-chains occurs universally and is important for binding and catalysis. Flexibility of large parts of a protein which rearrange or move are particularly interesting and will be discussed here. We differentiate between certain categories of large-scale flexibility although the boundaries between them are diffuse: flexibility of peptide segments, domain motions and order-disorder transitions of spatially contigous regions. The domains may be flexibly linked to allow rather unrestricted motion or the motion may be constrained to certain modes. The polypeptide segments linking the domains show characteristic structural features. The various categories of flexibility will be illustrated with the following examples. (a) Small protein proteinase inhibitors which are rather rigid molecules which provide binding surfaces complementary to their cognate proteases, but also show limited segmental flexibility and adaptation. (b) Large plasma inhibitors which exhibit large conformational changes upon interaction with proteases probably for regulatory purposes. (c) Pancreatic serine proteases which employ a disorder-order transition of their activation domain as a means to regulate enzymic activity. (d) Immunoglobulins in which rather unrestricted and also hinged domain motions occur in different parts of the molecule probably to allow binding to antigens in different arrangements. (e) Citrate synthase which adopts open and closed forms by a hinged domain motion to bind substrates and release products and to perform the catalytic condensation reaction, respectively. (f) The bifunctional multienzyme complex riboflavin synthase in which two enzymes (alpha and beta) catalyse two consecutive enzymic reactions. The beta-subunits form a shell, in which the alpha-subunits are enclosed. Diffusional motion of the catalytic intermediates is therefore restricted

  3. SU-E-T-585: Optically-Stimulated Luminescent Dosimeters for Monitoring Pacemaker Dose in Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Apicello, L [Hofstra University, Hempstead, NY (United States); Riegel, A; Jamshidi, A [North Shore LIJ Health System, Lake Success, NY (United States)

    2015-06-15

    Purpose: A sufficient amount of ionizing radiation can cause failure to components of pacemakers. Studies have shown that permanent damage can occur after a dose of 10 Gy and minor damage to functionality occurs at doses as low as 2 Gy. Optically stimulated thermoluminescent dosimeters (OSLDs) can be used as in vivo dosimeters to predict dose to be deposited throughout the treatment. The purpose of this work is to determine the effectiveness of using OSLDs for in vivo dosimetry of pacemaker dose. Methods: As part of a clinical in vivo dosimetry experience, OSLDs were placed at the site of the pacemaker by the therapist for one fraction of the radiation treatment. OSLD measurements were extrapolated to the total dose to be received by the pacemaker during treatment. A total of 79 measurements were collected from November 2011 to December 2013 on six linacs. Sixty-six (66) patients treated in various anatomical sites had the dose of their pacemakers monitored. Results: Of the 79 measurements recorded, 76 measurements (96 %) were below 2 Gy. The mean and standard deviation were 50.12 ± 76.41 cGy. Of the 3 measurements that exceeded 2 Gy, 2 measurements matched the dose predicted in the treatment plan and 1 was repeated after an unexpectedly high Result. The repeated measurement yielded a total dose less than 2 Gy. Conclusion: This analysis suggests OSLDs may be used for in vivo monitoring of pacemaker dose. Further research should be performed to assess the effect of increased backscatter from the pacemaker device.

  4. The circadian neuropeptide PDF signals preferentially through a specific adenylate cyclase isoform AC3 in M pacemakers of Drosophila.

    Science.gov (United States)

    Duvall, Laura B; Taghert, Paul H

    2012-01-01

    The neuropeptide Pigment Dispersing Factor (PDF) is essential for normal circadian function in Drosophila. It synchronizes the phases of M pacemakers, while in E pacemakers it decelerates their cycling and supports their amplitude. The PDF receptor (PDF-R) is present in both M and subsets of E cells. Activation of PDF-R stimulates cAMP increases in vitro and in M cells in vivo. The present study asks: What is the identity of downstream signaling components that are associated with PDF receptor in specific circadian pacemaker neurons? Using live imaging of intact fly brains and transgenic RNAi, we show that adenylate cyclase AC3 underlies PDF signaling in M cells. Genetic disruptions of AC3 specifically disrupt PDF responses: they do not affect other Gs-coupled GPCR signaling in M cells, they can be rescued, and they do not represent developmental alterations. Knockdown of the Drosophila AKAP-like scaffolding protein Nervy also reduces PDF responses. Flies with AC3 alterations show behavioral syndromes consistent with known roles of M pacemakers as mediated by PDF. Surprisingly, disruption of AC3 does not alter PDF responses in E cells--the PDF-R(+) LNd. Within M pacemakers, PDF-R couples preferentially to a single AC, but PDF-R association with a different AC(s) is needed to explain PDF signaling in the E pacemakers. Thus critical pathways of circadian synchronization are mediated by highly specific second messenger components. These findings support a hypothesis that PDF signaling components within target cells are sequestered into "circadian signalosomes," whose compositions differ between E and M pacemaker cell types.

  5. The circadian neuropeptide PDF signals preferentially through a specific adenylate cyclase isoform AC3 in M pacemakers of Drosophila.

    Directory of Open Access Journals (Sweden)

    Laura B Duvall

    Full Text Available The neuropeptide Pigment Dispersing Factor (PDF is essential for normal circadian function in Drosophila. It synchronizes the phases of M pacemakers, while in E pacemakers it decelerates their cycling and supports their amplitude. The PDF receptor (PDF-R is present in both M and subsets of E cells. Activation of PDF-R stimulates cAMP increases in vitro and in M cells in vivo. The present study asks: What is the identity of downstream signaling components that are associated with PDF receptor in specific circadian pacemaker neurons? Using live imaging of intact fly brains and transgenic RNAi, we show that adenylate cyclase AC3 underlies PDF signaling in M cells. Genetic disruptions of AC3 specifically disrupt PDF responses: they do not affect other Gs-coupled GPCR signaling in M cells, they can be rescued, and they do not represent developmental alterations. Knockdown of the Drosophila AKAP-like scaffolding protein Nervy also reduces PDF responses. Flies with AC3 alterations show behavioral syndromes consistent with known roles of M pacemakers as mediated by PDF. Surprisingly, disruption of AC3 does not alter PDF responses in E cells--the PDF-R(+ LNd. Within M pacemakers, PDF-R couples preferentially to a single AC, but PDF-R association with a different AC(s is needed to explain PDF signaling in the E pacemakers. Thus critical pathways of circadian synchronization are mediated by highly specific second messenger components. These findings support a hypothesis that PDF signaling components within target cells are sequestered into "circadian signalosomes," whose compositions differ between E and M pacemaker cell types.

  6. Crystal structure analysis reveals functional flexibility in the selenocysteine-specific tRNA from mouse.

    Directory of Open Access Journals (Sweden)

    Oleg M Ganichkin

    Full Text Available BACKGROUND: Selenocysteine tRNAs (tRNA(Sec exhibit a number of unique identity elements that are recognized specifically by proteins of the selenocysteine biosynthetic pathways and decoding machineries. Presently, these identity elements and the mechanisms by which they are interpreted by tRNA(Sec-interacting factors are incompletely understood. METHODOLOGY/PRINCIPAL FINDINGS: We applied rational mutagenesis to obtain well diffracting crystals of murine tRNA(Sec. tRNA(Sec lacking the single-stranded 3'-acceptor end ((ΔGCCARNA(Sec yielded a crystal structure at 2.0 Å resolution. The global structure of (ΔGCCARNA(Sec resembles the structure of human tRNA(Sec determined at 3.1 Å resolution. Structural comparisons revealed flexible regions in tRNA(Sec used for induced fit binding to selenophosphate synthetase. Water molecules located in the present structure were involved in the stabilization of two alternative conformations of the anticodon stem-loop. Modeling of a 2'-O-methylated ribose at position U34 of the anticodon loop as found in a sub-population of tRNA(Secin vivo showed how this modification favors an anticodon loop conformation that is functional during decoding on the ribosome. Soaking of crystals in Mn(2+-containing buffer revealed eight potential divalent metal ion binding sites but the located metal ions did not significantly stabilize specific structural features of tRNA(Sec. CONCLUSIONS/SIGNIFICANCE: We provide the most highly resolved structure of a tRNA(Sec molecule to date and assessed the influence of water molecules and metal ions on the molecule's conformation and dynamics. Our results suggest how conformational changes of tRNA(Sec support its interaction with proteins.

  7. Functional Flexibility of Intestinal IgA – Broadening the Fine Line

    Science.gov (United States)

    Slack, Emma; Balmer, Maria Luisa; Fritz, Jörg H.; Hapfelmeier, Siegfried

    2012-01-01

    Intestinal bacteria outnumber our own human cells in conditions of both health and disease. It has long been recognized that secretory antibody, particularly IgA, is produced in response to these microbes and hypothesized that this must play an important role in defining the relationship between a host and its intestinal microbes. However, the exact role of IgA and the mechanisms by which IgA can act are only beginning to be understood. In this review we attempt to unravel the complex interaction between so-called “natural,” “primitive” (T-cell-independent), and “classical” IgA responses, the nature of the intestinal microbiota/intestinal pathogens and the highly flexible dynamic homeostasis of the mucosal immune system. Such an analysis reveals that low-affinity IgA is sufficient to protect the host from excess mucosal immune activation induced by harmless commensal microbes. However, affinity-maturation of “classical” IgA is essential to provide protection from more invasive commensal species such as segmented filamentous bacteria and from true pathogens such as Salmonella typhimurium. Thus a correlation is revealed between “sophistication” of the IgA response and aggressiveness of the challenge. A second emerging theme is that more-invasive species take advantage of host inflammatory mechanisms to more successfully compete with the resident microbiota. In many cases, the function of IgA may be to limit such inflammatory responses, either directly by coagulating or inhibiting virulence of bacteria before they can interact with the host or by modulating immune signaling induced by host recognition. Therefore IgA appears to provide an added layer of robustness in the intestinal ecosystem, promoting “commensal-like” behavior of its residents. PMID:22563329

  8. Combined application of extracorporeal membrane oxygenation and an artificial pacemaker in fulminant myocarditis in a child.

    Science.gov (United States)

    Ye, Sheng; Zhu, Lvchan; Ning, Botao; Zhang, Chenmei

    2017-06-01

    Fulminant myocarditis is severe and aggressive, but it is self-limited and usually has a favorable prognosis if the patients can survive the acute phase. When drug treatment is not effective, extracorporeal membrane oxygenation technology should be applied to support cardiopulmonary function. Extracorporeal membrane oxygenation can simultaneously support function of the left ventricle, right ventricle, and lungs, and provide stable blood circulation for patients with heart and respiratory failure, which allows sufficient time for the cardiopulmonary system to recover. Fulminant myocarditis affects cardiac systolic function, as well as the function of autorhythmic cells and the conduction system. If severe bradycardia or atrioventricular block appears, a pacemaker needs to be installed. We report a child with fulminant myocarditis who was treated with extracorporeal membrane oxygenation combined with an artificial pacemaker.

  9. [Current developments on the physiology of the cardiac atrial pacemaker an excitation conduction of the left atrium].

    Science.gov (United States)

    Arrigo, L; Avanzino, G L

    1979-06-30

    According to recent developments the atrial pacemaker area and the right atrium show a peculiar morpho-functional organization, i.e.: 1) The pacemaker area is formed of clusters of cells containing relatively few myofibrils and showing embryologic characteristics. Such cells are known as nodal cells and between these and the atrial muscles are in general situated transitional cells. Each cluster is separated from the other by collagenous boundaries. The resistance of the membranes to the current flow seems to be relatively low between the cells of the same cluster but the collagenous boundaries are, according to TRAUTWEIN e UCHIZONO (1963), very poor conductors. The pacemaker activity seems to originate inside the various clusters. 2) The functional relationships between the sinoatrial node and the atrioventricular node as well as the interatrial relationship would take place through preferential pathways. These pathways corresponding approximately to the tracts described by JAMES (1966) (anterior, posterior and middle internodal tracts) and to the interatrial or Bachmann bundle, seems to show a higher velocity conduction. In general the fibres of which the tracts are composed are neither morphologically nor functionally isolated from the atrial muscle. The functional consequences of the above mentioned nodal and atrial organization seems to be: a) The possible conditioning of the pacemaker functions by the various clusters activity i.e. the dominance of one cluster over another. b) The shifting of the pacemaker activity from one cluster to anothr due to the arrival of nervous stimuli or chemical substances, etc. According to some Authors as a consequence of the shift the pacemaker area can sometimes move out side the nodal tissue and settle inside an area belonging to the internodal pathways. c) Another consequence of the shift can be the different involvement of the conducting pathways which can lead to a change in the dynamics of the atrial invasion by the

  10. Effects of elastic-band resistance exercise on balance, mobility and gait function, flexibility and fall efficacy in elderly people.

    Science.gov (United States)

    Kwak, Cheol-Jin; Kim, You Lim; Lee, Suk Min

    2016-11-01

    [Purpose] The purpose of this study was to analyze the effects of elastic-band resistance exercise on balance, gait function, flexibility and fall efficacy in the elderly people of rural community. [Subjects and Methods] It is selected by 45 outpatients. They have come into the clinic continually to treat of physical therapy at least 1-2 times for a week. A group treated with both general physical therapy and elastic-band resistance exercise (23 patients), and the other group treated with only general physical therapy (22 patients). Elastic-band resistance exercise is composed of 8 movements of lower extremity joints. It is performed for 30 minutes during 8 weeks by 3 times for a week. It is measured and recorded at the pre and post test that sit and reach test (SRT), functional reach test (FRT), timed up and go test (TUG) for every subjects by measurement equipments. And, subjects performed for the form of performance and question as its rated scale by Berg's balance scale (BBS), dynamic gait index (DGI), activities-specific balance confidence scale (ABC). [Results] In the study, both the elastic-band exercise group and the general physical therapy group showed a significant improvement in balance, gait function, flexibility and fall efficacy. And the group with elastic-band resistance exercise showed more effectiveness than the contrast group in value of variation. [Conclusion] From this study, it was confirmed that elastic-band resistance exercise has influence on balance, gait function, flexibility and fall efficacy are working for agriculture of elderly people of rural community. Based on this result, elastic-band resistance exercise can be better instrument and easier to elderly people of rural community for the improvement in balance, gait function, flexibility and fall efficacy as it performing along with and reciprocal physical therapy.

  11. Effects of elastic-band resistance exercise on balance, mobility and gait function, flexibility and fall efficacy in elderly people

    Science.gov (United States)

    Kwak, Cheol-Jin; Kim, You Lim; Lee, Suk Min

    2016-01-01

    [Purpose] The purpose of this study was to analyze the effects of elastic-band resistance exercise on balance, gait function, flexibility and fall efficacy in the elderly people of rural community. [Subjects and Methods] It is selected by 45 outpatients. They have come into the clinic continually to treat of physical therapy at least 1–2 times for a week. A group treated with both general physical therapy and elastic-band resistance exercise (23 patients), and the other group treated with only general physical therapy (22 patients). Elastic-band resistance exercise is composed of 8 movements of lower extremity joints. It is performed for 30 minutes during 8 weeks by 3 times for a week. It is measured and recorded at the pre and post test that sit and reach test (SRT), functional reach test (FRT), timed up and go test (TUG) for every subjects by measurement equipments. And, subjects performed for the form of performance and question as its rated scale by Berg’s balance scale (BBS), dynamic gait index (DGI), activities-specific balance confidence scale (ABC). [Results] In the study, both the elastic-band exercise group and the general physical therapy group showed a significant improvement in balance, gait function, flexibility and fall efficacy. And the group with elastic-band resistance exercise showed more effectiveness than the contrast group in value of variation. [Conclusion] From this study, it was confirmed that elastic-band resistance exercise has influence on balance, gait function, flexibility and fall efficacy are working for agriculture of elderly people of rural community. Based on this result, elastic-band resistance exercise can be better instrument and easier to elderly people of rural community for the improvement in balance, gait function, flexibility and fall efficacy as it performing along with and reciprocal physical therapy. PMID:27942147

  12. Dislocation of an infected and abandoned pacemaker lead.

    Science.gov (United States)

    Kostopoulou, Anna G; Kyrzopoulos, Stamatios D; Livanis, Efthimios G

    2012-11-01

    We present a case of pacemaker lead dislodgment in an 83-year-old patient with a pacemaker infection. Initially, the generator and the proximal part of the leads were removed, and the remaining leads were severed and abandoned. Twenty-five days later, dislodgment of both abandoned leads and systemic infection were documented. The leads were then surgically removed without further complications.

  13. Pacemaker implantation complication rates in elderly and young patients.

    Science.gov (United States)

    Ozcan, Kazım Serhan; Osmonov, Damirbek; Altay, Servet; Dönmez, Cevdet; Yıldırım, Ersin; Türkkan, Ceyhan; Güngör, Barış; Ekmekçi, Ahmet; Alper, Ahmet Taha; Gürkan, Kadir; Erdinler, Izzet

    2013-01-01

    To evaluate the complication rate differences between elderly and younger patients who receive a permanent pacemaker implantation. We reviewed all cases admitted to our institution between January 2008 and June 2009 with symptomatic bradyarrhythmia for whom a permanent pacemaker was implanted. Beginning in June 2009, we prospectively collected data from all patients with the same diagnosis and procedure. The frequency of complications due to the pacemaker implantation procedure was evaluated and compared between young (pacemaker, 259 patients (45.1%) were below and 315 patients (54.9%) were above or at 70 years of age. There were 240 (92.7%) and 19 (7.3%) dual-chamber pacemaker (DDD) and single-chamber pacemaker (VVI) implanted patients in the younger group, and 291 (76.8%) and 73 (23.2%) DDD and VVI pacemaker implanted patients in the elderly group, respectively. The complication rate was 39 (15.1%) out of 259 young patients and 24 (7.6%) out of 315 elderly patients. Postprocedural complications were statistically lower in the elderly patients than in younger patients (P = 0.005). A pacemaker implantation performed by an experienced operator is a safe procedure for patients of advanced age. The patients who are above 70 years old may have less complication rates than the younger patients.

  14. A NEW METHOD FOR DIAGRAMMING PACEMAKER/HEART INTERACTION

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Advancements in technology have enhanced the performance of pacemakers but made the interaction between the pacemaker and the heart becoming increasingly complex, and its is difficult to interpret the paced ECGs (PGCGs). This paper introduces a brief method to interpret PECGs, which illustrate the timing intervals graphically and avoid using symbols and strings.

  15. Role of sinoatrial node architecture in maintaining a balanced source-sink relationship and synchronous cardiac pacemaking

    Directory of Open Access Journals (Sweden)

    Sathya D Unudurthi

    2014-11-01

    Full Text Available Normal heart rhythm (sinus rhythm depends on regular activity of the sinoatrial node (SAN, a heterogeneous collection of specialized myocytes in the right atrium. SAN cells, in general, possess a unique electrophysiological profile that promotes spontaneous electrical activity (automaticity. However, while automaticity is required for normal pacemaking, it is not necessarily sufficient. Less appreciated is the importance of the elaborate structure of the SAN complex for proper pacemaker function. Here, we review the important structural features of the SAN with a focus on how these elements help manage a precarious balance between electrical charge generated by the SAN (source and the charge needed to excite the surrounding atrial tissue (sink. We also discuss how compromised source-sink balance due, for example to fibrosis, may promote SAN dysfunction, characterized by slow and/or asynchronous pacemaker activity and even failure, in the setting of cardiovascular disease (e.g. heart failure, atrial fibrillation. Finally, we discuss implications of the source-sink balance in the SAN complex for cell and gene therapies aimed at creating a biological pacemaker as replacement or bridge to conventional electronic pacemakers.

  16. Transitioning between Work and Family Roles as a Function of Boundary Flexibility and Role Salience

    Science.gov (United States)

    Winkel, Doan E.; Clayton, Russell W.

    2010-01-01

    This study investigates the manner in which people separate their work and family roles and how they manage the boundaries of these two important roles. Specifically, we focus on how role flexibility and salience influence transitions between roles. Results indicate that the ability and willingness to flex a role boundary and role salience are…

  17. Transitioning between Work and Family Roles as a Function of Boundary Flexibility and Role Salience

    Science.gov (United States)

    Winkel, Doan E.; Clayton, Russell W.

    2010-01-01

    This study investigates the manner in which people separate their work and family roles and how they manage the boundaries of these two important roles. Specifically, we focus on how role flexibility and salience influence transitions between roles. Results indicate that the ability and willingness to flex a role boundary and role salience are…

  18. Genetic and phenotypically flexible components of seasonal variation in immune function

    NARCIS (Netherlands)

    Versteegh, M. A.; Helm, B.; Kleynhans, E. J.; Gwinner, E.; Tieleman, B. I.

    2014-01-01

    Animals cope with seasonal variation in environmental factors by adjustments of physiology and life history. When seasonal variation is partly predictable, such adjustments can be based on a genetic component or be phenotypically flexible. Animals have to allocate limited resources over different de

  19. Pacemaker implantation complication rates in elderly and young patients

    Directory of Open Access Journals (Sweden)

    Özcan KS

    2013-08-01

    Full Text Available Kazim Serhan Özcan, Damirbek Osmonov, Servet Altay, Cevdet Dönmez, Ersin Yildirim, Ceyhan Türkkan, Baris Güngör, Ahmet Ekmekçi, Ahmet Taha Alper, Kadir Gürkan, İzzet ErdinlerDepartment of Cardiology, Siyami Ersek Cardiovascular and Thoracic Surgery Center, Istanbul, TurkeyAims: To evaluate the complication rate differences between elderly and younger patients who receive a permanent pacemaker implantation.Methods: We reviewed all cases admitted to our institution between January 2008 and June 2009 with symptomatic bradyarrhythmia for whom a permanent pacemaker was implanted. Beginning in June 2009, we prospectively collected data from all patients with the same diagnosis and procedure. The frequency of complications due to the pacemaker implantation procedure was evaluated and compared between young (<70 years old and elderly (≥70 years old patients.Results: Among 574 patients with a permanent pacemaker, 259 patients (45.1% were below and 315 patients (54.9% were above or at 70 years of age. There were 240 (92.7% and 19 (7.3% dual-chamber pacemaker (DDD and single-chamber pacemaker (VVI implanted patients in the younger group, and 291 (76.8% and 73 (23.2% DDD and VVI pacemaker implanted patients in the elderly group, respectively. The complication rate was 39 (15.1% out of 259 young patients and 24 (7.6% out of 315 elderly patients. Postprocedural complications were statistically lower in the elderly patients than in younger patients (P = 0.005.Conclusion: A pacemaker implantation performed by an experienced operator is a safe procedure for patients of advanced age. The patients who are above 70 years old may have less complication rates than the younger patients.Keywords: complications of pacemaker implantation, elderly patients, permanent pacemaker

  20. Interruption of pacemaker signals is mediated by GABAergic inhibition of the pacemaker nucleus in the African electric fish Gymnarchus niloticus.

    Science.gov (United States)

    Zhang, Ying; Kawasaki, Masashi

    2007-06-01

    The wave-type African weakly electric fish Gymnarchus niloticus produces electric organ discharges (EODs) from an electric organ in the tail that is driven by a pacemaker complex in the medulla, which consists of a pacemaker nucleus, two lateral relay nuclei and a medial relay nucleus. The prepacemaker nucleus (PPn) in the area of the dorsal posterior nucleus of the thalamus projects exclusively to the pacemaker nucleus and is responsible for EOD interruption behavior. The goal of the present study is to test the existence of inhibition of the pacemaker nucleus by the PPn. Immunohistochemical results showed clear anti-GABA immunoreactive labeling of fibers and terminals in the pacemaker nucleus, but no apparent anti-glycine immunoreactivity anywhere in the pacemaker complex. GABA injection into the pacemaker nucleus could induce EOD interruptions that are comparable to the interruptions induced by glutamate injection into the PPn. Application of the GABA(A) receptor blocker bicuculline methiodide reversibly eliminated the effects of stimulation of the PPn. Thus the EOD interruption behavior in Gymnarchus is mediated through GABAergic inhibition of the pacemaker nucleus by the PPn.

  1. Exponential synchronization rate of Kuramoto oscillators in the presence of a pacemaker.

    Science.gov (United States)

    Wang, Yongqiang; Doyle, Francis J

    2012-08-27

    The exponential synchronization rate is addressed for Kuramoto oscillators in the presence of a pacemaker. When natural frequencies are identical, we prove that synchronization can be ensured even when the phases are not constrained in an open half-circle, which improves the existing results in the literature. We derive a lower bound on the exponential synchronization rate, which is proven to be an increasing function of pacemaker strength, but may be an increasing or decreasing function of local coupling strength. A similar conclusion is obtained for phase locking when the natural frequencies are non-identical. An approach to trapping phase differences in an arbitrary interval is also given, which ensures synchronization in the sense that synchronization error can be reduced to an arbitrary level.

  2. The Immunoendocrine Thymus as a Pacemaker of Lifespan.

    Science.gov (United States)

    Csaba, György

    2016-06-01

    The thymus develops from an endocrine area of the foregut, and retains the ancient potencies of this region. However, later it is populated by bone marrow originated lymphatic elements and forms a combined organ, which is a central part of the immune system as well as an influential element of the endocrine orchestra. Thymus produces self-hormones (thymulin, thymosin, thymopentin, and thymus humoral factor), which are participating in the regulation of immune cell transformation and selection, and also synthesizes hormones similar to that of the other endocrine glands such as melatonin, neuropeptides, and insulin, which are transported by the immune cells to the sites of requests (packed transport). Thymic (epithelial and immune) cells also have receptors for hormones which regulate them. This combined organ, which is continuously changing from birth to senescence seems to be a pacemaker of life. This function is basically regulated by the selection of self-responsive thymocytes as their complete destruction helps the development (up to puberty) and their gradual release in case of weakened control (after puberty) causes the erosion of cells and intercellular material, named aging. This means that during aging, self-destructive and non-protective immune activities are manifested under the guidance of the involuting thymus, causing the continuous irritation of cells and organs. Possibly the pineal body is the main regulator of the pacemaker, the neonatal removal of which results in atrophy of thymus and wasting disease and its later corrosion causes the insufficiency of thymus. The co-involution of pineal and thymus could determine the aging and the time of death without external intervention; however, external factors can negatively influence both of them.

  3. Electromagnetic interference with pacemakers caused by portable media players.

    Science.gov (United States)

    Thaker, Jay P; Patel, Mehul B; Jongnarangsin, Krit; Liepa, Valdis V; Thakur, Ranjan K

    2008-04-01

    Electromagnetic fields generated by electrical devices may cause interference with permanent pacemakers. Media players are becoming a common mode of portable entertainment. The most common media players used worldwide are iPods. These devices are often carried in a shirt chest pocket, which may place the devices close to an implanted pacemaker. The purpose of this study was to determine if iPods cause interference with pacemakers. In this prospective, single-blinded study, 100 patients who had cardiac pacemakers were tested with four types of iPods to assess for interference. Patients were monitored by a single-channel ECG monitor as well as the respective pacemaker programmer via the telemetry wand. iPods were tested by placing them 2 inches anterior to the pacemaker and wand for up to 10 seconds. To simulate actual use, standard-issue headphones were plugged into the iPods. To maintain consistency, the volume was turned up maximally, and the equalizer was turned off. A subset of 25 patients underwent testing on 2 separate days to assess for reproducibility of interference. Pacemaker interference was categorized as type I or type II telemetry interference. Type I interference was associated with atrial and/or ventricular high rates on rate histograms. Type II interference did not affect pacemaker rate counters. Electromagnetic emissions from the four iPods also were evaluated in a Faraday cage to determine the mechanism of the observed interference. One hundred patients (63 men and 37 women; mean age 77.1 +/- 7.6 years) with 11 single-chamber pacemakers and 89 dual-chamber pacemakers underwent 800 tests. The incidence of any type of interference was 51% of patients and 20% of tests. Type I interference was seen in 19% of patients and type II in 32% of patients. Reproducibility testing confirmed that interference occurred regardless of pacing configuration (unipolar or bipolar), pacing mode (AAI, VVI, or DDD), and from one day to the next. Electromagnetic emissions

  4. Permanent cardiac pacemaker in infants and children.

    Science.gov (United States)

    Dasmahapatra, H K; Jamieson, M P; Brewster, G M; Doig, B; Pollock, J C

    1986-08-01

    Between October 1970 and November 1984, 26 infants and children aged 11 days to 18 years (mean 5.7 years) received 42 permanent cardiac pacemakers (26 primary implants, 16 re-implants) for congenital or surgically acquired heart block, bradycardia and sinus node dysfunction. Twenty-two patients had unipolar pacing and 4 bipolar pacing. Of 26 primary implantations, 2 had fixed rate epicardial pacing, 16 ventricular demand pacing (13 epicardial, 3 endocardial), 3 epicardial VAT (P-synchronous) pacing and 5 DDD (universal) pacing (4 epicardial, one endocardial). Fourteen patients required a further 19 operations for change of generators (16), ventricular lead (1), generator site (1) and generator encasing (1). Thirty-day hospital mortality was 11.5% (3/26), of which one death was possibly related to pacing failure. Four patients died during the follow-up period (3 months to 10 years; mean 3.4 years). Sixteen of the 19 survivors achieved complete symptomatic relief, without any medical therapy. Our results indicate that modern cardiac pacemaker systems are safe and reliable, and are associated with major relief of symptoms in this age group.

  5. Nanogenerator-based dual-functional and self-powered thin patch loudspeaker or microphone for flexible electronics

    Science.gov (United States)

    Li, Wei; Torres, David; Díaz, Ramón; Wang, Zhengjun; Wu, Changsheng; Wang, Chuan; Lin Wang, Zhong; Sepúlveda, Nelson

    2017-05-01

    Ferroelectret nanogenerators were recently introduced as a promising alternative technology for harvesting kinetic energy. Here we report the device's intrinsic properties that allow for the bidirectional conversion of energy between electrical and mechanical domains; thus extending its potential use in wearable electronics beyond the power generation realm. This electromechanical coupling, combined with their flexibility and thin film-like form, bestows dual-functional transducing capabilities to the device that are used in this work to demonstrate its use as a thin, wearable and self-powered loudspeaker or microphone patch. To determine the device's performance and applicability, sound pressure level is characterized in both space and frequency domains for three different configurations. The confirmed device's high performance is further validated through its integration in three different systems: a music-playing flag, a sound recording film and a flexible microphone for security applications.

  6. Smooth-surface silver nanowire electrode with high conductivity and transparency on functional layer coated flexible film

    Energy Technology Data Exchange (ETDEWEB)

    Lee, So Hee; Lim, Sooman; Kim, Haekyoung, E-mail: hkkim@ynu.ac.kr

    2015-08-31

    Transparent conductive electrode (TCE) with silver nanowires has been widely studied as an alternative of indium tin oxide for flexible electronic or optical devices such as organic light-emitting diodes, and solar cells. However, it has an issue of surface roughness due to nanowire's intrinsic properties. Here, to achieve a smooth electrode with high conductivity and transmittance on polyethylene terephthalate (PET) substrates, a functional layer of poly(N-vinylpyrrolidone) (PVP) is utilized with a mechanical transfer process. The silver nanowire electrode on PVP-coated PET with low surface roughness of 9 nm exhibits the low sheet resistance of 18 Ω □{sup −1} and high transmittance of 87.6%. It is produced by transferring the silver nanowire electrode spin-coated on the glass to PVP-coated PET using a pressure of 10 MPa for 10 min. Silver nanowire electrode on PVP-coated PET demonstrates the stable sheet resistance of 18 Ω □{sup −1} after the mechanical taping test due to strong adhesion between PVP functional layer and silver nanowires. Smooth TCE with silver nanowires could be proposed as a transparent electrode for flexible electronic or optical devices, which consist of thin electrical active layers on TCE. - Highlights: • Silver nanowire (Ag NWs) transparent electrodes were fabricated on flexible film. • Flexible film was coated with poly N-vinylpyrrolidone (PVP). • PVP layer plays roles as an adhesive layer and matrix in electrode. • Ag NWs electrode exhibited with low surface roughness of 9 nm. • Ag NWs electrode has a low resistance (18 Ω ☐{sup −1}) and high transmittance (87.6%)

  7. Design and Implementation of programmable Cardiac Pacemaker Using VHDL

    Directory of Open Access Journals (Sweden)

    Omkar Dwivedi

    2015-05-01

    Full Text Available Pacemaker design has evolved very rapidly over the last several years. There has been a great deal of work in enhancing the programmability of pacemakers, to enable them to be programmed to work with different selected operating parameters, and indeed to work in different modes. In Taiwan, about 70%of cardiac pacemakerpatients are paced only from the ventricle with some pacing parameter programmability. This paper goal is to design a cardiac pacemaker with various NBG modes. A state machine approach has been followed to achieve the desired purpose. The pacemaker system is divide into three main sections i.e. controlling unit, sensing unit and pulse generator. In this paper we mainly concentrate on controlling unit and pulse generator. It has been developed using VHDL coding and implemented in hardware using FPGA. In a simple pacemaker process i.e. single chamber or dual chamber pacemaker, first an input signal or an event is detected in heart through leads. When the input signal is detected a timer generates a delay for approximately 0.8 sec. It is the time between two consecutive heartbeats, thus giving us 72 heartbeats per minute. Once the generated delay expires, sensing unit again start detecting a new event. If any event is detected we repeat the process of detection and waiting. If no event is detected we need to provide an electrical pulse to the heart and then repeat the whole process of detection and waiting. The code has been optimized and modified for different pacemaker modes.

  8. Neck Pain One Week after Pacemaker Generator Replacement.

    Science.gov (United States)

    Graham, Ross F; Wightman, John M

    2015-07-01

    The incidence of cardiac pacemaker implantation has risen markedly in the past three decades, making awareness of possible postprocedural complications critical to the emergency physician. This case is the first documented instance of internal jugular (IJ) deep vein thrombosis (DVT) from an uncomplicated pacemaker generator replacement. A patient presented to an Emergency Department with a 2-day history of mild left temporal headache migrating to his left neck. The patient did not volunteer this information, but review of systems revealed a temporary transvenous pacemaker inserted through the right IJ vein 1 week previously during a routine exchange of a left-sided cardiac pacemaker generator. Manipulation of the existing pacemaker wires entering the left subclavian vein was minimal. Computed tomographic angiography of the neck demonstrated near-complete thrombotic occlusion of the entire length of his left IJ vein. This required hospital admission for observation and treatment with anticoagulation. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: DVT, with thrombotic extension into adjacent vessels anywhere along the course of pacemaker wires, should be considered by the emergency provider in the evaluation of head, neck, or upper extremity symptoms after recent or remote implantation or manipulation of a transvenous cardiac pacemaker, including generator replacement. Failure to identify and treat appropriately could result in significant morbidity and mortality from airway edema, septic thrombophlebitis, superior vena cava syndrome, superior sagittal sinus thrombosis, or pulmonary embolism. Published by Elsevier Inc.

  9. A devices' game of thrones: cardiac resynchronization therapy vs. pacemaker.

    Science.gov (United States)

    Moura-Ferreira, Sara; Gonçalves, Helena; Oliveira, Marco; Primo, João; Fonseca, Paulo; Ribeiro, José; Santos, Elisabeth; Pelicano, Nuno; Martins, Dinis; Gama, Vasco

    2017-04-18

    Oversensing can interfere with biventricular pacing. Cardiac Resynchronization Therapy (CRT) output inhibition due to automatic brady mode change from a sensing to a pacing mode of a previously implanted pacemaker as it reached battery capacity depleted indicator has not been previously published in the medical literature. We report the first case of CRT output inhibition in a pacemaker dependent patient due to electrical stimuli from a previously right-sided implanted pacemaker, after unaware reversion of OVO mode (O = no chambers paced; V = ventricular sensing; O = no response to sensing) to backup VVI (V = ventricular pacing; V = ventricular sensing; I = inhibitory response to sensing) when it reached the elective replacement interval. This paper emphasizes the importance of knowing the distinct pacemaker brady mode behaviours after battery capacity depleted indicator has been reached, according to the pacemakers' manufacturer, including the possibility of automatic brady mode change from sensing to pacing mode. It also highlights the potential for severe bradycardia or asystole of this automatic brady mode change from a previously implanted pacemaker in pacemaker dependent patients submitted to CRT upgrade.

  10. Rechargeable silver-modified mercuric oxide-zinc cell for cardiac pacemakers.

    Science.gov (United States)

    Tyers, G F; Hughes, H C; Brownlee, R R; Manley, N J; Gorman, I N

    1976-11-04

    Tests were conducted on rechargeable mercury-zinc pacemaker batteries under simulated and actual biologic conditions, using a variety of discharge rates and charging schedules. In tests on 96 cells at a 6.4 milliampere (ma) discharge, recharging once every 15 months of simulated pacing at a 25 microampere (mua) drain, the earliest cell failure occurred after an equivalent of 50 years of pacing. The mean pacing equivalent for all 96 cells was more than 140 years. In 6.4 ma discharge tests on 24 cells, recharging once every 8 days of simulated pacing, only 1 cell in 24 failed after an equivalent of more than 500 years of pacing (actual time 2 years). In tests on 13 cells pacing at a 200 mua drain without recharging, the simulated mean duration of pacing before total discharge was 4.8 years. Seven other cells at a 200 mua drain with periodic recharging continue to function normally after more than 7 years of actual time, simulating 56 years of pacing at a 25 mua drain. Cardiac pacemakers using the rechargeable mercury-zinc cell have been implanted in animals for more than 2 1/2 years and in patients for more than 1 year with all units continuing to function satisfactorily. It has been demonstrated unequivocally that a rechargeable mercury-zinc pacemaker will function continuously for more than 4 years without recharging and that periodic recharging will extend pacing life far beyond that predicted for lithium and nuclear primary power sources.

  11. Evaluation of Safety and Efficacy of Qinming8631 DR Implantable Cardiac Pacemaker in Chinese Patients: A Prospective, Multicenter, Randomized Controlled Trial of the First Domestically Developed Pacemaker of China.

    Science.gov (United States)

    Xiang, Mei-Xiang; Wang, Dong-Qi; Xu, Jing; Zhang, Zheng; Hu, Jian-Xin; Wang, Dong-Mei; Gu, Xiang; Liu, He-Ping; Guo, Tao; Yang, Xiang-Jun; Ling, Feng; Lin, Jia-Feng; Cai, Shang-Lang; Zhu, Guo-Bin; Wang, Jian-An

    2016-11-20

    High cost of imported pacemakers is a main obstacle for Chinese patients suffering from bradyarrhythmia, and a domestically developed pacemaker will help lower the burden. This study aimed to evaluate the safety and efficacy of Qinming8631 DR (Qinming Medical, Baoji, China), the first domestically developed dual-chamber pacemaker of China, compared with a commercially available pacemaker Talos DR (Biotronik, Berlin, Germany) in Chinese patients. A prospective randomized trial was conducted at 14 centers in China. Participants were randomized into trial (Qinming8631 DR) and control (Talos DR) groups. Parameters of the pacing systems were collected immediately after device implantation and during follow-ups. The effective pacing rate at 6-month follow-up was recorded as the primary end point. Electrical properties, magnet response, single- and double-pole polarity conversion, rate response function, and adverse events of the pacing system were analyzed. The Cochran-Mantel-Haenszel Chi-square test, paired t-test, and Wilcoxon signed-rank test were used for measuring primary qualitative outcomes and comparing normally and abnormally distributed measurement data. A total of 225 patients with a diagnosis of bradyarrhythmia and eligible for this study were randomly enrolled into the trial (n = 113) and control (n = 112) groups. They underwent successful pacemaker implantation with acceptable postoperative pacing threshold and sensitivity. Effective pacing rates of trial and control groups were comparable both in the full analysis set and the per protocol set (81.4% vs. 79.5%, P = 0.712 and 95.4% vs. 89.5%, P = 0.143, respectively). In both data sets, noninferiority of the trial group was above the predefined noninferiority limit(-9.5%). This study established the noninferiority of Qinming8631 DR to Talos DR. The safety and efficacy of Qinming8631 DR pacemaker were comparable to those of Talos DR in treating patients with cardiac bradyarrhythmia.

  12. The National Survey of Cardiac Pacemakers and Cardioverter Defibrillators

    Directory of Open Access Journals (Sweden)

    Gholamrerza Shafieian

    2006-07-01

    Full Text Available Background: Permanent pacemakers provide effective relief of symptoms and are life-saving in patients with symptomatic heart block. Implantable cardioverter defibrillators (ICD are also increasingly recognized as life-saving tools in various groups of patients with malignant ventricular tachyarrhythmias. Methods: As part of the “world survey on pacemaker and ICD implantations”, a survey of all device implantations in Iran during the year 2001 was performed. Data was collected and cross-checked through three sources i.e. direct contact with implanting physicians, pacemaker companies and the governmental pacemaker distributing body.Results: During the year studied, 1635 patients received permanent pacemakers. 88% were new implants at an estimated rate of 24 per million population. The mean age of patients was 65 years and 56.2% were male. 40 cardiologists and 19 surgeons implanted the pacemakers at 27 centers throughout the country. Complete heart block was consistently the most common indication at all centers (mean 56.1%, sick sinus syndrome being the next most common one (mean 20.8%. 69% of the pacemakers were single chamber pacemakers. Transvenous insertion of bipolar steroid-eluting passive fixation leads was the predominant practice at most centers. A total of 60 ICDs were implanted at 7 centers by 9 cardiologists. 45% of ICD implants were dual chamber devices.Conclusion: The survey is the only one available right now and provides useful information about the prevailing pacemaker and defibrillator implantation practice in Iran. Future surveys would be facilitated if a standardized implant registry such as that used in Europe were established in this country.

  13. Routine chest radiography after permanent pacemaker implantation: Is it necessary?

    Directory of Open Access Journals (Sweden)

    Edwards N

    2005-01-01

    Full Text Available Background and Aims: Chest radiographs (CXRs are performed routinely after permanent pacemaker implantation to identify pacemaker lead position and exclude pneumothorax. We assessed the clinical value and need for this procedure. Design: Retrospective analysis of pacemaker data and CXRs following permanent pacemaker insertion between December 2002 and February 2004. Materials and Methods: Post-procedural CXRs were available in 125/126 consecutive patients after either first endocardial pacemaker implantation or insertion of at least one new lead. Subclavian vein puncture was used for venous access in all cases. CXRs were examined to establish the incidence of pneumothorax and assess pacing lead positions. The clinical records were examined in all patients who had subsequent CXRs or a further pacemaker procedure to identify the indication for these and to establish whether CXR had influenced patient management. Results: In total, 192 post-procedural CXRs were performed, either postero-anterior (PA and/or lateral views. Ventricular and/or atrial pacing lead contour and electrode position was considered radiographically appropriate in 86% CXRs. Fourteen per cent of post-procedural radiographs were considered to have radiologically sub-optimal pacemaker lead positioning. None of the patients with these "abnormal" radiographs experienced subsequent pacemaker complications or had further radiographs recorded at a later date. Later repeat CXRs were performed in 16 patients (13% but only 3 patients (2% had pacing abnormalities as the primary indication. All three had satisfactory pacing lead position on initial post-implantation and later radiographs, but required further procedures for lead re-positioning. Iatrogenic pneumothorax occurred in one patient (incidence 0.8% in our series. CXR confirmed the clinical diagnosis and allowed an assessment of size to guide treatment. Conclusion: Routine CXR after permanent pacemaker insertion is not necessary in

  14. Firing Patterns and Transitions in Coupled Neurons Controlled by a Pacemaker

    Institute of Scientific and Technical Information of China (English)

    LI Mei-Sheng; LU Qi-Shao; DUAN Li-Xia; WANG Qing-Yun

    2008-01-01

    @@ To reveal the dynamics of neuronal networks with pacemakers, the firing patterns and their transitions are investigated in a ring HR neuronal network with gap junctions under the control of a pacemaker. Compared with the situation without pacemaker, the neurons in the network can exhibit various firing patterns as the external current is applied or the coupling strength of pacemaker varies. The results are beneficial for understanding the complex cooperative behaviour of large neural assemblies with pacemaker control.

  15. A flexible approach for assessing functional landscape connectivity, with application to greater sage-grouse (Centrocercus urophasianus.

    Directory of Open Access Journals (Sweden)

    Seth M Harju

    Full Text Available Connectivity of animal populations is an increasingly prominent concern in fragmented landscapes, yet existing methodological and conceptual approaches implicitly assume the presence of, or need for, discrete corridors. We tested this assumption by developing a flexible conceptual approach that does not assume, but allows for, the presence of discrete movement corridors. We quantified functional connectivity habitat for greater sage-grouse (Centrocercus urophasianus across a large landscape in central western North America. We assigned sample locations to a movement state (encamped, traveling and relocating, and used Global Positioning System (GPS location data and conditional logistic regression to estimate state-specific resource selection functions. Patterns of resource selection during different movement states reflected selection for sagebrush and general avoidance of rough topography and anthropogenic features. Distinct connectivity corridors were not common in the 5,625 km(2 study area. Rather, broad areas functioned as generally high or low quality connectivity habitat. A comprehensive map predicting the quality of connectivity habitat across the study area validated well based on a set of GPS locations from independent greater sage-grouse. The functional relationship between greater sage-grouse and the landscape did not always conform to the idea of a discrete corridor. A more flexible consideration of landscape connectivity may improve the efficacy of management actions by aligning those actions with the spatial patterns by which animals interact with the landscape.

  16. Polysiloxane Functionalized Carbon Dots and Their Cross-Linked Flexible Silicone Rubbers for Color Conversion and Encapsulation of White LEDs.

    Science.gov (United States)

    Wang, Yunfeng; Yin, Zhengmao; Xie, Zheng; Zhao, Xinxin; Zhou, Chuanjian; Zhou, Shuyun; Chen, Ping

    2016-04-20

    In this work, aminopropylmethylpolysiloxane (AMS) functionalized luminescent carbon dots (AMS-CDs) were prepared via a one-step solvothermal method. AMS-CDs could be self- or co-cross-linking with AMS to form 3D flexible transparent silicone rubbers (SRs) where CDs acted as cross-linking points, so the loading fraction of AMS-CDs could be adjusted from 10 to 100 wt %, thus modulating fluorescence properties and flexibility of silicone rubbers. Because of the self-curing property and high thermal stability, AMS-CDs were also studied in white LEDs (WLEDs), serving as a color conversion and encapsulation layer of GaN based blue LEDs simultaneously that would avoid the traditional problem of poor compatibility between emitting and packaging materials. And the color coordinate of AMS-CDs based WLEDs (0.33, 0.28) was very close to the pure white light. In addition, the obtained CDs cross-linked SRs had good transparency (T > 80%) at 510-1400 nm and high refractive indexes (1.33-1.54) that could meet the need of commercial packaging materials and optical application. AMS-CDs were also promising to be used in the UV LEDs based WLEDs according to their wide wavelength emission and flexible optoelectronic device.

  17. [Pacemaker implantation in dogs: results of the last 30 years].

    Science.gov (United States)

    François, L; Chetboul, V; Nicolle, A; Carlos, C; Borenstein, N; Pouchelon, J L

    2004-07-01

    Pacemaker implantation in veterinary practice is still not well known and remains uncommon. However, this technique is the only possible way to cure animals suffering from symptomatic bradycardia whose state does not improve with a medical treatment. In most cases, the use of pacemakers in veterinary medicine leads to the disappearance of the clinical and electrocardiographic signs. This retrospective study concerning the last 30 years draws up an evaluation of the improvements, advantages and drawbacks of this method. Moreover, this study allows the understanding of the evolution of pacemakers' use in veterinary cardiology.

  18. Acute pericarditis with cardiac tamponade induced by pacemaker implantation.

    Science.gov (United States)

    Shingaki, Masami; Kobayashi, Yutaka; Suzuki, Haruo

    2015-11-01

    An 87-year-old woman was diagnosed with third-degree atrioventricular block and underwent pacemaker implantation. On postoperative day 12, she experienced cardiac tamponade that was suspected on computed tomography to be caused by lead perforation; therefore, we performed open-heart surgery. However, we could not identify a perforation site on the heart, and drained a 400-mL exudative pericardial effusion. Subsequently, we diagnosed the pericardial effusion as due to pericarditis induced by pacemaker implantation. It is sometimes difficult to distinguish pericarditis from pacemaker lead perforation, so both should be included in the differential diagnosis.

  19. Case Report of Radiotherapy to a Breast Cancer Patient with a Pacemaker

    Energy Technology Data Exchange (ETDEWEB)

    Chae, Seung Hoon; Park, Jang Pil; Lee, Yang Hoon; Yoo, Suk Hyun [Dept. of Radiation Oncology, Seoul National University Hospital, Seoul (Korea, Republic of); Seong, Won Mo [Interdisciplinary Program of Radiation Applied Life Science, Seoul National University College of Medicine, Seoul (Korea, Republic of); Kim, Kyu Bo [Dept. of Radiation Oncology, Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2012-09-15

    In this study, we considerate our radiation therapy process for the breast cancer patient implanted a pacemaker applying the machine movement surgery, shielding, beam selection. We perform radiation therapy to a 54 years old, breast cancer patient implanted a pacemaker. The patient underwent a surgery to move the position of a pacemaker to right side breast after consultation with cardiology department. Prescribed dose was 5,040 cGy and daily dose 180 cGy for 28 fractions. The 10 MV photon energy, field size 0/9.5x20 cm, half beam and opposing portal irradiation are used. To find out appropriate thickness of shielding board, we carried out an experiment using a solid water phantom (30x30x7 cm), a Farmer-type chamber (TN30013, PTW, Germany) and a shielding board (Pb 28x27x0.1 cm). We calculated expected absorbed dose to te pacemaker with absorb ratio and shielding ratio. In the PTP system (Eclipse, Varian, USA), we figured out how much radiation would be absorbed to the machine with and without shielding. First day of the radiation therapy, we measured head scatter to the pacemaker with MOSFET Dose Verification System (TN-RD-70-W, Medical Canada Ltd., Canada). In the phantom measurement, we found out appropriate thickness was 2 mm of shielding board. In the RTP, when using 2 mm shielding the pacemaker will be absorbed 11.5-38.2 cGy and DVH is 77.3 cGy. In the first day of the therapy, 4.3 cGy was measured so 120.4 cGy was calculated during total therapy. The patient was free from any side effects, and the machine also normally functioned. As the report of association which have public confidence became superannuated, there is lack of data about new machine. We believe that radiation therapy to these kind of patients could be done successfully with co-operation, patient-suitable planning, accurate QA, frequent in-vivo dosimetry and monitoring.

  20. Pacemakers and implantable cardioverter defibrillators, unknown to chest radiography: Review, complications and systematic reading

    Energy Technology Data Exchange (ETDEWEB)

    Alandete Germán, Salvador Pascual, E-mail: salaiger@gmail.com; Isarria Vidal, Santiago, E-mail: isarria@comv.es; Domingo Montañana, María Luisa, E-mail: domingo.luimon@gmail.com; De la vía Oraá, Esperanza, E-mail: esviao82@gmail.com; Vilar Samper, José, E-mail: vilarsamper@gmail.com

    2015-03-15

    Highlights: •Radiologists have an important function in the evaluation of these devices. •We revise their radiological appearances and possible complications. •The knowledge in normal aspects and complications is important for radiologist. •To ensure an accurate reading of the chest x-ray, we present a systematic approach. -- Abstract: Chest X-ray is the imaging technique of choice for an initial study of pacemakers and implantable cardio-defibrillators (ICD). Radiologists have an important role in the evaluation of its initial placement and in the assessment during its follow-up. For this reason, it is necessary to know not only the different existing devices and its components but also the reasons of malfunction or possible complications. The purpose of this article is to do a systematic review of the different types of pacemakers and ICD. We review their usual radiological appearances, the possible complications which might take place and its causes of malfunctioning.

  1. 具有自动搜索心房滞后功能的起搏器对房性心律失常近期影响研究%Recent impact study of automatic search function of the pacemaker atrial hysteresis on atrial arrhythmias

    Institute of Scientific and Technical Information of China (English)

    李永东; 葛智平; 温慧华; 徐安杰

    2013-01-01

    目的 探讨具有自动搜索心房滞后功能的起搏器对房性心律失常近期影响,评估其临床疗效和安全性.方法 选择植入Identity Adx DDD 5286型双腔起搏器病态窦房结综合征的患者43例.起搏器植入后不打开带自动搜索的心房滞后,保持起搏器出厂设置;术后3个月随访时程控为在DDD模式下打开带自动搜索的心房滞后,共随访6个月.比较起搏器植入前后及打开心房滞后模式后心房起搏百分比、动态心电图(DCG)房性心律失常发生情况.结果 与术前比较术后3个月DCG24 h房性早搏(简称房早)次数和房性心动过速(简称房速)、心房颤动(简称房颤)阵数增加(P<0.05);房早、房速和房颤的发作例数增加(P<0.05).打开具有自动搜索功能的心房滞后模式与未打开该模式比较:心房的起搏百分比明显降低[0.54(0.41,0.71)vs.0.82(0.65,0.93),P<0.05];DCG24h房早次数和房速、房颤阵数明显减少(P<0.05).房早、房速和房颤的发作例数减少(P<0.05).结论 具有自动搜索功能的心房滞后模式可以明显减少心房起搏的比例,减少房性心律失常的发生;打开具有自动搜索功能的心房滞后模式安全可靠.%Objective To explore the recent influences of pacemaker with automatic search function of atrial hysteresis on atrial arrhythmias,to evaluate its clinical efficacy and safety.Methods Identity Adx DDD 5286 implanted dual chamber pacemaker for sick sinus syndrome in 43 cases.Automatic search of atrial lag was not opened with after pacemaker implantation,and the pacemaker settings was kept.Follow-up program after 3 months,DDD mode with automatic search of atrial lag was opened,and this mods was followed up for 6 months,comparing the atrial pacing percentage and DCG atrial tachyarrhythmias of pacemaker implantation to opening atrium lag mode.Results Compared with the preoperative and operative 3 months later,DCG 24 h showed that APB and atrial

  2. Persistent fever after pacemaker lead extraction

    Directory of Open Access Journals (Sweden)

    Maria Carmo Pereira Nunes

    2016-05-01

    Full Text Available The implant indication of cardiac electronic devices continues to expand; therefore, we have observed increasing complications related to their removal. We describe the case of a patient who presented with prolonged bloodstream infection after having undergone removal of a pacemaker. After extensive workup for fever of unknown origin and antibiotic therapy without any improvement, it was possible to demonstrate a foreign body in the right subclavian vein and superior vena cava corresponding to the distal part of the right ventricular lead. Endovascular removal of the foreign body and prolonged antibiotic administration was followed by complete resolution of the clinical picture. We ascribed the difficulty in diagnosing the source of the infection especially to the lack of local manifestations.

  3. Neutron absorbed dose in a pacemaker CMOS

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Guzman G, K. A.; Valero L, C. Y.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L., E-mail: candy_borja@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-11-15

    The absorbed dose due to neutrons by a Complementary Metal Oxide Semiconductor (CMOS) has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes a patient that must be treated by radiotherapy with a linear accelerator; the pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. When the Linac is working in Bremsstrahlung mode an undesirable neutron field is produced due to photoneutron reactions; these neutrons could damage the CMOS putting the patient at risk during the radiotherapy treatment. In order to estimate the neutron dose in the CMOS a Monte Carlo calculation was carried out where a full radiotherapy vault room was modeled with a W-made spherical shell in whose center was located the source term of photoneutrons produced by a Linac head operating in Bremsstrahlung mode at 18 MV. In the calculations a phantom made of tissue equivalent was modeled while a beam of photoneutrons was applied on the phantom prostatic region using a field of 10 x 10 cm{sup 2}. During simulation neutrons were isotropically transported from the Linac head to the phantom chest, here a 1 {theta} x 1 cm{sup 2} cylinder made of polystyrene was modeled as the CMOS, where the neutron spectrum and the absorbed dose were estimated. Main damages to CMOS are by protons produced during neutron collisions protective cover made of H-rich materials, here the neutron spectrum that reach the CMOS was calculated showing a small peak around 0.1 MeV and a larger peak in the thermal region, both connected through epithermal neutrons. (Author)

  4. Case report: use caution when applying magnets to pacemakers or defibrillators for surgery.

    Science.gov (United States)

    Schulman, Peter M; Rozner, Marc A

    2013-08-01

    The application of a magnet to a pacemaker (intended to cause asynchronous pacing) or implanted cardioverter defibrillator (intended to prevent shocks) during surgery without a clear understanding of actual magnet function(s) or precautions can have unexpected, untoward, or harmful consequences. In this report, we present 3 cases in which inadequate assessment of cardiac implanted electronic device (CIED) function, coupled with magnet application, contributed to or resulted in inappropriate antitachycardia pacing or shocks, CIED damage, or patient injury. Although these cases might be rare, they reinforce the need for a timely, detailed preoperative review of CIED function and programming as recommended by the American Society of Anesthesiologists and the Heart Rhythm Society.

  5. Constraint Network Analysis (CNA): a Python software package for efficiently linking biomacromolecular structure, flexibility, (thermo-)stability, and function.

    Science.gov (United States)

    Pfleger, Christopher; Rathi, Prakash Chandra; Klein, Doris L; Radestock, Sebastian; Gohlke, Holger

    2013-04-22

    For deriving maximal advantage from information on biomacromolecular flexibility and rigidity, results from rigidity analyses must be linked to biologically relevant characteristics of a structure. Here, we describe the Python-based software package Constraint Network Analysis (CNA) developed for this task. CNA functions as a front- and backend to the graph-based rigidity analysis software FIRST. CNA goes beyond the mere identification of flexible and rigid regions in a biomacromolecule in that it (I) provides a refined modeling of thermal unfolding simulations that also considers the temperature-dependence of hydrophobic tethers, (II) allows performing rigidity analyses on ensembles of network topologies, either generated from structural ensembles or by using the concept of fuzzy noncovalent constraints, and (III) computes a set of global and local indices for quantifying biomacromolecular stability. This leads to more robust results from rigidity analyses and extends the application domain of rigidity analyses in that phase transition points ("melting points") and unfolding nuclei ("structural weak spots") are determined automatically. Furthermore, CNA robustly handles small-molecule ligands in general. Such advancements are important for applying rigidity analysis to data-driven protein engineering and for estimating the influence of ligand molecules on biomacromolecular stability. CNA maintains the efficiency of FIRST such that the analysis of a single protein structure takes a few seconds for systems of several hundred residues on a single core. These features make CNA an interesting tool for linking biomacromolecular structure, flexibility, (thermo-)stability, and function. CNA is available from http://cpclab.uni-duesseldorf.de/software for nonprofit organizations.

  6. High-Performance Flexible Organic Nano-Floating Gate Memory Devices Functionalized with Cobalt Ferrite Nanoparticles.

    Science.gov (United States)

    Jung, Ji Hyung; Kim, Sunghwan; Kim, Hyeonjung; Park, Jongnam; Oh, Joon Hak

    2015-10-07

    Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe2O4) nanoparticles (NPs) as charge trap sites and pentacene as a p-type semiconductor. Monodisperse CoFe2O4 NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle-particle interactions. CoFe2O4 NP-based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read I(on)/I(off)) of ≈2.98 × 10(3), and excellent data retention. Fast switching behaviors are observed due to the exceptional charge trapping/release capability of CoFe2O4 NPs surrounded by the oleate layer, which acts as an alternative tunneling dielectric layer and simplifies the device fabrication process. Furthermore, the NFGM devices show excellent thermal stability, and flexible memory devices fabricated on plastic substrates exhibit remarkable mechanical and electrical stability. This study demonstrates a viable means of fabricating highly flexible, high-performance organic memory devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Successful pacing using a batteryless sunlight-powered pacemaker.

    Science.gov (United States)

    Haeberlin, Andreas; Zurbuchen, Adrian; Schaerer, Jakob; Wagner, Joerg; Walpen, Sébastien; Huber, Christoph; Haeberlin, Heinrich; Fuhrer, Juerg; Vogel, Rolf

    2014-10-01

    Today's cardiac pacemakers are powered by batteries with limited energy capacity. As the battery's lifetime ends, the pacemaker needs to be replaced. This surgical re-intervention is costly and bears the risk of complications. Thus, a pacemaker without primary batteries is desirable. The goal of this study was to test whether transcutaneous solar light could power a pacemaker. We used a three-step approach to investigate the feasibility of sunlight-powered cardiac pacing. First, the harvestable power was estimated. Theoretically, a subcutaneously implanted 1 cm(2) solar module may harvest ∼2500 µW from sunlight (3 mm implantation depth). Secondly, ex vivo measurements were performed with solar cells placed under pig skin flaps exposed to a solar simulator and real sunlight. Ex vivo measurements under real sunlight resulted in a median output power of 4941 µW/cm(2) [interquartile range (IQR) 3767-5598 µW/cm(2), median skin flap thickness 3.0 mm (IQR 2.7-3.3 mm)]. The output power strongly depended on implantation depth (ρSpearman = -0.86, P pacemaker powered by a 3.24 cm(2) solar module was implanted in vivo in a pig to measure output power and to pace. In vivo measurements showed a median output power of >3500 µW/cm(2) (skin flap thickness 2.8-3.84 mm). Successful batteryless VVI pacing using a subcutaneously implanted solar module was performed. Based on our results, we estimate that a few minutes of direct sunlight (irradiating an implanted solar module) allow powering a pacemaker for 24 h using a suitable energy storage. Thus, powering a pacemaker by sunlight is feasible and may be an alternative energy supply for tomorrow's pacemakers. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  8. Effects of 16-week functional movement screen training program on strength and flexibility of elite high school baseball players.

    Science.gov (United States)

    Song, Hong-Sun; Woo, Seung-Seok; So, Wi-Young; Kim, Kwang-Jun; Lee, Joohyung; Kim, Joo-Young

    2014-04-01

    Functional Movement Screen (FMS) is a way to pretest functional movement. This study examined the effects of the FMS training program on the strength and flexibility of 62 elite male high school baseball players (31 in the training group, 31 in the control group). All players who received less than two points on each FMS test item had to join the 16-week, three times weekly FMS training program. To analyze results among the FMS participants, measures including intraclass correlation coefficient (ICC) and repeated measure ANOVA were utilized. The Kappa coefficient was 0.805 when the intraclass correlation coefficient of the three participants was inspected. Strength showed a significant interaction depending on time and group (hand grip strength: P=0.011, bench press and squat both for one-repetition maximum (1RM): P=0.001 and P=0.008, respectively). Back muscle strength did not show a significant difference (P=0.660). Trunk forward flexion showed no interaction depending on time and groups (P=0.983) but trunk extension backward showed significant differences depending on groups (P=0.004) and time (P=0.001). Splits showed a significant difference depending on time and groups (P=0.004). The FMS training program improved the strength and flexibility of elite high school baseball players.

  9. Flexible Flatfoot

    Science.gov (United States)

    ... this page. Please enable Javascript in your browser. Flexible Flatfoot What Is Flatfoot? Flatfoot is often a ... may develop as a result of a flatfoot. Flexible Flatfoot Flexible flatfoot is one of the most ...

  10. Pacemaker implantation after catheter ablation for atrial fibrillation.

    Science.gov (United States)

    Deshmukh, Abhishek J; Yao, Xiaoxi; Schilz, Stephanie; Van Houten, Holly; Sangaralingham, Lindsey R; Asirvatham, Samuel J; Friedman, Paul A; Packer, Douglas L; Noseworthy, Peter A

    2016-01-01

    Sinus node dysfunction requiring pacemaker implantation is commonly associated with atrial fibrillation (AF), but may not be clinically apparent until restoration of sinus rhythm with ablation or cardioversion. We sought to determine frequency, time course, and predictors for pacemaker implantation after catheter ablation, and to compare the overall rates to a matched cardioversion cohort. We conducted a retrospective analysis using a large US commercial insurance database and identified 12,158 AF patients who underwent catheter ablation between January 1, 2005 and December 31, 2012. Over an average of 2.4 years of follow-up, 5.6 % of the patients underwent pacemaker implantation. Using the Cox proportional hazards models, we found that risk of risks of pacemaker implantation was associated with older age (50-64 and ≥65 versus pacemaker implantation between ablation patients and propensity score (PS)-matched cardioversion groups (3.5 versus. 4.1 % at 1 year and 8.8 versus 8.3 % at 5 years). Overall, pacemaker implantation occurs in about 1/28 patients within 1 year of catheter ablation. The overall implantation rate decreased between 2005 and 2012. Furthermore, the risk after ablation is similar to cardioversion, suggesting that patients require pacing due to a common underlying electrophysiologic substrate, rather than the ablation itself.

  11. The hyperpolarization-activated channel HCN4 is required for the generation of pacemaker action potentials in the embryonic heart

    Science.gov (United States)

    Stieber, Juliane; Herrmann, Stefan; Feil, Susanne; Löster, Jana; Feil, Robert; Biel, Martin; Hofmann, Franz; Ludwig, Andreas

    2003-01-01

    Hyperpolarization-activated, cyclic nucleotide-gated cation currents, termed If or Ih, are generated by four members of the hyperpolarization-activated, cyclic nucleotide-gated cation (HCN) channel family. These currents have been proposed to contribute to several functions including pacemaker activity in heart and brain, control of resting potential, and neuronal plasticity. Transcripts of the HCN4 isoform have been found in cardiomyocytes and neurons, but the physiological role of this channel is unknown. Here we show that HCN4 is essential for the proper function of the developing cardiac conduction system. In wild-type embryos, HCN4 is highly expressed in the cardiac region where the early sinoatrial node develops. Mice lacking HCN4 channels globally, as well as mice with a selective deletion of HCN4 in cardiomyocytes, died between embryonic days 9.5 and 11.5. On average, If in cardiomyocytes from mutant embryos is reduced by 85%. Hearts from HCN4-deficient embryos contracted significantly slower compared with wild type and could not be stimulated by cAMP. In both wild-type and HCN4-/- mice, cardiac cells with “primitive” pacemaker action potentials could be found. However, cardiac cells with “mature” pacemaker potentials, observed in wild-type embryos starting at day 9.0, were not detected in HCN4-deficient embryos. Thus, HCN4 channels are essential for the proper generation of pacemaker potentials in the emerging sinoatrial node. PMID:14657344

  12. Rapid high-amplitude circumferential slow wave propagation during normal gastric pacemaking and dysrhythmias.

    Science.gov (United States)

    O'Grady, G; Du, P; Paskaranandavadivel, N; Angeli, T R; Lammers, W J E P; Asirvatham, S J; Windsor, J A; Farrugia, G; Pullan, A J; Cheng, L K

    2012-07-01

    Gastric slow waves propagate aborally as rings of excitation. Circumferential propagation does not normally occur, except at the pacemaker region. We hypothesized that (i) the unexplained high-velocity, high-amplitude activity associated with the pacemaker region is a consequence of circumferential propagation; (ii) rapid, high-amplitude circumferential propagation emerges during gastric dysrhythmias; (iii) the driving network conductance might switch between interstitial cells of Cajal myenteric plexus (ICC-MP) and circular interstitial cells of Cajal intramuscular (ICC-IM) during circumferential propagation; and (iv) extracellular amplitudes and velocities are correlated. An experimental-theoretical study was performed. High-resolution gastric mapping was performed in pigs during normal activation, pacing, and dysrhythmia. Activation profiles, velocities, and amplitudes were quantified. ICC pathways were theoretically evaluated in a bidomain model. Extracellular potentials were modeled as a function of membrane potentials. High-velocity, high-amplitude activation was only recorded in the pacemaker region when circumferential conduction occurred. Circumferential propagation accompanied dysrhythmia in 8/8 experiments was faster than longitudinal propagation (8.9 vs 6.9 mm s(-1) ; P = 0.004) and of higher amplitude (739 vs 528 μV; P = 0.007). Simulations predicted that ICC-MP could be the driving network during longitudinal propagation, whereas during ectopic pacemaking, ICC-IM could outpace and activate ICC-MP in the circumferential axis. Experimental and modeling data demonstrated a linear relationship between velocities and amplitudes (P propagation. Rapid circumferential propagation also emerges during a range of gastric dysrhythmias, elevating extracellular amplitudes and organizing transverse wavefronts. One possible explanation for these findings is bidirectional coupling between ICC-MP and circular ICC-IM networks. © 2012 Blackwell Publishing Ltd.

  13. Anesthesia for pacemaker implant in an adult patient with unoperated univentricular heart. Case report.

    Science.gov (United States)

    Hobaika, Adriano Bechara de Souza; Procópio, André Luís Pontes; Pereira, Marcelo Luiz Souza; Coimbra, Aristóteles Pereira; Fernandes, Magda Lourenço; Pires, Kleber Costa de Castro

    2007-02-01

    Single ventricle is a rare abnormality, affecting 1% of the patients with congenital cardiopathy. Only 11 cases of patients with unoperated univentricular heart older than 50 years were reported in the literature. The aim of this report was to describe the anesthetic conduct in a patient with univentricular heart undergoing pacemaker implant. A female patient, 47 years old, with double outlet left ventricle, L-transposition of the great vessels, and pulmonary stenosis, without prior surgical correction, was scheduled for definitive implant of a sequential dual-chamber pacemaker. The ABPM demonstrated second degree atrioventricular block and a mean heart rate of 45 bpm. Preoperative exams showed a hematocrit of 57%, normal coagulation studies, and preserved ventricular function. Monitoring consisted of pulse oxymeter, ECG on D(II) and V5, IBP, capnograph, and gas analyzer. A temporary transcutaneous pacemaker was available in case of severe bradycardia. Anesthesia was induced with fentanyl (0.25 mg), etomidate (20 mg), and atracurium (35 mg). Four minutes after anesthetic induction, the heart rate decreased to 30 bmp and 1 mg of atropine was administered with reversal of the bradycardia. Anesthesia was maintained with 2.5% sevoflurane, 60% room air, and 40% oxygen. Hemodynamic parameters and oxygen saturation remained stable. The patient was transferred to the intensive care unit in stable condition and extubated at the end of the procedure. The anesthetic conduct for pacemaker implant in a 47-year old patient with non-operated double outlet left ventricle and pulmonary stenosis was appropriate, since it allowed the procedure to be performed.

  14. Capsule endoscopy in patients with cardiac pacemakers, implantable cardioverter defibrillators and left heart assist devices.

    Science.gov (United States)

    Bandorski, Dirk; Höltgen, Reinhard; Stunder, Dominik; Keuchel, Martin

    2014-01-01

    According to the recommendations of the US Food and Drug Administration and manufacturers, capsule endoscopy should not be used in patients carrying implanted cardiac devices. For this review we considered studies indexed (until 30.06.2013) in Medline [keywords: capsule endoscopy, small bowel endoscopy, cardiac pacemaker, implantable cardioverter defibrillator, interference, left heart assist device], technical information from Given Imaging and one own publication (not listed in Medline). Several in vitro and in vivo studies included patients with implanted cardiac devices who underwent capsule endoscopy. No clinically relevant interference was noticed. Initial reports on interference with a simulating device were not reproduced. Furthermore technical data of PillCam (Given Imaging) demonstrate that the maximum transmission power is below the permitted limits for cardiac devices. Hence, impairment of cardiac pacemaker, defibrillator or left ventricular heart assist device function by capsule endoscopy is not expected. However, wireless telemetry can cause dysfunction of capsule endoscopy recording. Application of capsule endoscopy is feasible and safe in patients with implanted cardiac devices such as pacemakers, cardioverter defibrillators, and left heart assist devices. Development of new technologies warrants future re-evaluation.

  15. Powering a leadless pacemaker using a PiezoMEMS energy harvester

    Science.gov (United States)

    Jackson, Nathan; Olszewski, Oskar; O'Murchu, Cian; Mathewson, Alan

    2017-06-01

    MEMS based vibrational energy harvesting devices have been a highly researched topic over the past decade. The application targeted in this paper focuses on a leadless pacemaker that will be implanted in the right ventricle of the heart. A leadless pacemaker requires the same functionality as a normal pacemaker, but with significantly reduced volume. The reduced volume limits the space for a battery; therefore an energy harvesting device is required. This paper compares varying the dimensions of a linear MEMS based piezoelectric energy harvester that can harvest energy from the mechanical vibrations of the heart due to shock induced vibration. Typical MEMS linear energy harvesting devices operate at high frequency (heart acts as a series of impulses as opposed to traditional sinusoidal vibration force with high acceleration (1-4 g). Therefore the design of a MEMS harvester that is based on shock-induced vibration is necessary. PiezoMEMS energy harvesting devices consisting of a silicon substrate and mass with aluminium nitride piezoelectric material were developed and characterized using acceleration forces that mimic the heartbeat. Peak powers of up to 25μW were obtained at 1 g acceleration with a powder density of approximately 1.5 mW cm-3.

  16. Impact of Pacemaker Lead Characteristics on Pacemaker Related Infection and Heart Perforation: A Nationwide Population-Based Cohort Study.

    Directory of Open Access Journals (Sweden)

    Yu-Sheng Lin

    Full Text Available Several risk factors for pacemaker (PM related complications have been reported. However, no study has investigated the impact of lead characteristics on pacemaker-related complications.Patients who received a new pacemaker implant from January 1997 to December 2011 were selected from the Taiwan National Health Insurance Database. This population was grouped according to the pacemaker lead characteristics in terms of fixation and insulation. The impact of the characteristics of leads on early heart perforation was analyzed by multivariable logistic regression analysis, while the impact of the lead characteristics on early and late infection and late heart perforation over a three-year period were analyzed using Cox regression. This study included 36,104 patients with a mean age of 73.4±12.5 years. In terms of both early and late heart perforations, there were no significant differences between groups across the different types of fixation and insulations. In the multivariable Cox regression analysis, the pacemaker-related infection rate was significantly lower in the active fixation only group compared to either the both fixation (OR, 0.23; 95% CI, 0.07-0.80; P = 0.020 or the passive fixation group (OR, 0.26; 95% CI, 0.08-0.83; P = 0.023.There was no difference in heart perforation between active and passive fixation leads. Active fixation leads were associated with reduced risk of pacemaker-related infection.

  17. Impact of Pacemaker Lead Characteristics on Pacemaker Related Infection and Heart Perforation: A Nationwide Population-Based Cohort Study.

    Science.gov (United States)

    Lin, Yu-Sheng; Chen, Tien-Hsing; Hung, Sheng-Ping; Chen, Dong Yi; Mao, Chun-Tai; Tsai, Ming-Lung; Chang, Shih-Tai; Wang, Chun-Chieh; Wen, Ming-Shien; Chen, Mien-Cheng

    2015-01-01

    Several risk factors for pacemaker (PM) related complications have been reported. However, no study has investigated the impact of lead characteristics on pacemaker-related complications. Patients who received a new pacemaker implant from January 1997 to December 2011 were selected from the Taiwan National Health Insurance Database. This population was grouped according to the pacemaker lead characteristics in terms of fixation and insulation. The impact of the characteristics of leads on early heart perforation was analyzed by multivariable logistic regression analysis, while the impact of the lead characteristics on early and late infection and late heart perforation over a three-year period were analyzed using Cox regression. This study included 36,104 patients with a mean age of 73.4±12.5 years. In terms of both early and late heart perforations, there were no significant differences between groups across the different types of fixation and insulations. In the multivariable Cox regression analysis, the pacemaker-related infection rate was significantly lower in the active fixation only group compared to either the both fixation (OR, 0.23; 95% CI, 0.07-0.80; P = 0.020) or the passive fixation group (OR, 0.26; 95% CI, 0.08-0.83; P = 0.023). There was no difference in heart perforation between active and passive fixation leads. Active fixation leads were associated with reduced risk of pacemaker-related infection.

  18. Conformational Flexibility Enables Function of a BECN1 Region Essential for Starvation-Mediated Autophagy

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Yang; Ramanathan, Arvind; Glover, Karen M.; Stanley, Christopher; Sanishvili, Ruslan; Chakravarthy, Srinivas; Yang, Zhongyu; Colbert, C L; Sinha, Sangita C.

    2016-04-05

    BECN1 is essential for autophagy, a critical eukaryotic cellular homeostasis pathway. Here we delineate a highly conserved BECN1 domain located between previously characterized BH3 and coiled-coil domains and elucidate its structure and role in autophagy. The 2.0 angstrom sulfur-single-wavelength anomalous dispersion X-ray crystal structure of this domain demonstrates that its N-terminal half is unstructured while its C-terminal half is helical; hence, we name it the flexible helical domain (FHD). Circular dichroism spectroscopy, double electron electron resonance electron paramagnetic resonance, and small-angle X-ray scattering (SAXS) analyses confirm that the FHD is partially disordered, even in the context of adjacent BECN1 domains. Molecular dynamic simulations fitted to SAXS data indicate that the FHD transiently samples more helical conformations. FHD helicity increases in 2,2,2-trifluoroethanol, suggesting it may become more helical upon binding. Lastly, cellular studies show that conserved FHD residues are required for starvation-induced autophagy. Thus, the FHD likely undergoes a binding-associated disorder to-helix transition, and conserved residues critical for this interaction are essential for starvation-induced autophagy.

  19. Phenotypic flexibility in digestive system structure and function in migratory birds and its ecological significance.

    Science.gov (United States)

    McWilliams, S R; Karasov, W H

    2001-03-01

    Birds during migration must satisfy the high energy and nutrient demands associated with repeated, intensive flight while often experiencing unpredictable variation in food supply and food quality. Solutions to such different challenges may often be physiologically incompatible. For example, increased food intake and gut size are primarily responsible for satisfying the high energy and nutrient demands associated with migration in birds. However, short-term fasting or food restriction during flight may cause partial atrophy of the gut that may limit utilization of ingested food energy and nutrients. We review the evidence available on the effects of long- and short-term changes in food quality and quantity on digestive performance in migratory birds, and the importance of digestive constraints in limiting the tempo of migration in birds. Another important physiological consequence of feeding in birds is the effect of diet on body composition dynamics during migration. Recent evidence suggests that birds utilize and replenish both protein and fat reserves during migration, and diet quality influences the rate of replenishment of both these reserves. We conclude that diet and phenotypic flexibility in both body composition and the digestive system of migratory birds are important in allowing birds to successfully overcome the often-conflicting physiological challenges of migration.

  20. From flexibility to function: Molecular dynamics simulations of conformational changes in chaperones and photoreceptors

    NARCIS (Netherlands)

    Singhal, K.

    2016-01-01

    Proteins are uniquely-shaped macromolecules that function as biological machines, and regulate a living cell’s behavior. Crucial to protein function is the folding of the polypeptide chain into a unique well-defined three-dimensional conformation. In complex cell environments, the spontaneous unassi

  1. HelioScan: a software framework for controlling in vivo microscopy setups with high hardware flexibility, functional diversity and extendibility.

    Science.gov (United States)

    Langer, Dominik; van 't Hoff, Marcel; Keller, Andreas J; Nagaraja, Chetan; Pfäffli, Oliver A; Göldi, Maurice; Kasper, Hansjörg; Helmchen, Fritjof

    2013-04-30

    Intravital microscopy such as in vivo imaging of brain dynamics is often performed with custom-built microscope setups controlled by custom-written software to meet specific requirements. Continuous technological advancement in the field has created a need for new control software that is flexible enough to support the biological researcher with innovative imaging techniques and provide the developer with a solid platform for quickly and easily implementing new extensions. Here, we introduce HelioScan, a software package written in LabVIEW, as a platform serving this dual role. HelioScan is designed as a collection of components that can be flexibly assembled into microscope control software tailored to the particular hardware and functionality requirements. Moreover, HelioScan provides a software framework, within which new functionality can be implemented in a quick and structured manner. A specific HelioScan application assembles at run-time from individual software components, based on user-definable configuration files. Due to its component-based architecture, HelioScan can exploit synergies of multiple developers working in parallel on different components in a community effort. We exemplify the capabilities and versatility of HelioScan by demonstrating several in vivo brain imaging modes, including camera-based intrinsic optical signal imaging for functional mapping of cortical areas, standard two-photon laser-scanning microscopy using galvanometric mirrors, and high-speed in vivo two-photon calcium imaging using either acousto-optic deflectors or a resonant scanner. We recommend HelioScan as a convenient software framework for the in vivo imaging community.

  2. Successful management of multiple permanent pacemaker complications – infection, 13 year old silent lead perforation and exteriorisation following failed percutaneous extraction, superior vena cava obstruction, tricuspid valve endocarditis, pulmonary embolism and prosthetic tricuspid valve thrombosis

    Science.gov (United States)

    Kaul, Pankaj; Adluri, Krishna; Javangula, Kalyana; Baig, Wasir

    2009-01-01

    A 59 year old man underwent mechanical tricuspid valve replacement and removal of pacemaker generator along with 4 pacemaker leads for pacemaker endocarditis and superior vena cava obstruction after an earlier percutaneous extraction had to be abandoned, 13 years ago, due to cardiac arrest, accompanied by silent, unsuspected right atrial perforation and exteriorisation of lead. Postoperative course was complicated by tricuspid valve thrombosis and secondary pulmonary embolism requiring TPA thrombolysis which was instantly successful. A review of literature of pacemaker endocarditis and tricuspid thrombosis along with the relevant management strategies is presented. We believe this case report is unusual on account of non operative management of right atrial lead perforation following an unsuccessful attempt at percutaneous removal of right sided infected pacemaker leads and the incidental discovery of the perforated lead 13 years later at sternotomy, presentation of pacemaker endocarditis with a massive load of vegetations along the entire pacemaker lead tract in superior vena cava, right atrial endocardium, tricuspid valve and right ventricular endocardium, leading to a functional and structural SVC obstruction, requirement of an unusually large dose of warfarin postoperatively occasioned, in all probability, by antibiotic drug interactions, presentation of tricuspid prosthetic valve thrombosis uniquely as vasovagal syncope and isolated hypoxia and near instantaneous resolution of tricuspid prosthetic valve thrombosis with Alteplase thrombolysis. PMID:19239701

  3. Sudden death and its risk factors after atrioventricular junction ablation and pacemaker implantation in patients with atrial fibrillation.

    Science.gov (United States)

    Wang, Ru-Xing; Lee, Hon-Chi; Li, Jia-Ping; Hodge, David O; Cha, Yong-Mei; Friedman, Paul A; Munger, Thomas M; Srivathsan, Komandoor; Pavri, Behzad B; Shen, Win-Kuang

    2017-01-01

    Although sudden death (SD) is a rare complication after atrioventricular junction (AVJ) ablation and permanent pacemaker implantation, the risk factors leading to this SD remain unknown. The purpose of this study was to investigate SD and its risk factors after ablate-and-pace strategy for rate control in atrial fibrillation (AF) patients during long-term follow-up. METHODS: From January 2005 to December 2009, we enrolled into this study 517 AF patients with AVJ ablation and right ventricular pacemaker implantation. Patients were divided into 2 groups, SD and non-SD. Cox proportional hazards models were used to assess potential risk factors for overall mortality and SD. During a mean follow-up of 25.8 ± 18.6 months (range, 3 days to 63.8 months), 53 patients died (15 with SD). Cox proportional hazards models showed that the presence of congestive heart failure, New York Heart Association functional class, chronic renal failure, and nonsustained ventricular tachycardia were risk factors that predicted overall mortality. For SD, the presence of dilated cardiomyopathy and mitral stenosis were associated risk factors. SD was exclusively seen in patients who had narrow QRS complex or right bundle branch block prior to AVJ ablation and pacemaker implantation; SD was not seen in any patient with preexisting complete left bundle branch block. Dilated cardiomyopathy, mitral stenosis, and baseline QRS morphology should be examined as potential risk factors for SD after AVJ ablation and pacemaker implantation. © 2016 Wiley Periodicals, Inc.

  4. A case of complete atrioventricular block: The use of magnetic resonance imaging conditional pacemakers for diagnosing cardiac sarcoidosis

    Directory of Open Access Journals (Sweden)

    Yosuke Miwa, MD

    2014-04-01

    Full Text Available A 50-year-old man presented to the emergency department with repeated episodes of faintness and exertional dyspnea, and was found to have an atrioventricular (AV block. Chest radiography and transthoracic echocardiography results were normal, without any evidence of heart failure, wall motion abnormalities, interventricular septum thinning, or bilateral hilar lymphadenopathy. A temporary pacemaker was implanted, followed by a permanent pacemaker. Chest computed tomography with contrast enhancement did not show abnormalities, including patent coronary arteries, lymph node adenopathy, and pulmonary abnormalities. Thus, an MRI conditional dual chamber pacemaker and leads were implanted. Six weeks following the implant, a cardiac MRI was performed to test for cardiac sarcoidosis. Although cine imaging showed normal left and right ventricular function, late gadolinium enhancement demonstrated multiple enhanced uptakes. Based on the results of the cardiac MRI, PET, and gallium scintigraphy, the most likely diagnosis was cardiac sarcoidosis. Although no abnormal findings were found on physical examination, blood work, chest radiography, and transthoracic echocardiogram, multiple regions of delayed enhancement were observed in the cardiac MRI. Thus, MRI conditional pacemakers are a useful tool for diagnosing cardiac sarcoidosis and early therapeutic intervention.

  5. Functionally Graded Polyimide Nanocomposite Foams for Ablative and Inflatable/Flexible/Deplorable Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the proposed research is to develop functionally graded polyimide foams as light-weight, high performance thermal protection systems (TPS) for...

  6. Flexible shape-memory scaffold for minimally invasive delivery of functional tissues

    Science.gov (United States)

    Montgomery, Miles; Ahadian, Samad; Davenport Huyer, Locke; Lo Rito, Mauro; Civitarese, Robert A.; Vanderlaan, Rachel D.; Wu, Jun; Reis, Lewis A.; Momen, Abdul; Akbari, Saeed; Pahnke, Aric; Li, Ren-Ke; Caldarone, Christopher A.; Radisic, Milica

    2017-10-01

    Despite great progress in engineering functional tissues for organ repair, including the heart, an invasive surgical approach is still required for their implantation. Here, we designed an elastic and microfabricated scaffold using a biodegradable polymer (poly(octamethylene maleate (anhydride) citrate)) for functional tissue delivery via injection. The scaffold’s shape memory was due to the microfabricated lattice design. Scaffolds and cardiac patches (1 cm × 1 cm) were delivered through an orifice as small as 1 mm, recovering their initial shape following injection without affecting cardiomyocyte viability and function. In a subcutaneous syngeneic rat model, injection of cardiac patches was equivalent to open surgery when comparing vascularization, macrophage recruitment and cell survival. The patches significantly improved cardiac function following myocardial infarction in a rat, compared with the untreated controls. Successful minimally invasive delivery of human cell-derived patches to the epicardium, aorta and liver in a large-animal (porcine) model was achieved.

  7. [Right heart failure after pacemaker implantation].

    Science.gov (United States)

    Gallego Galiana, Juan; López Castellanos, Genoveva; Gioia, Francesca; Ruiz Ortega, Raúl Antonio; Cobo Reinoso, Maria Eugenia; Manzano Espinosa, Luis

    2015-06-22

    Severe tricuspid regurgitation (TR) secondary to interference pacemaker (PM) cable is a rare cause of progressive right heart failure (HF), which can worsen patient outcomes. We present 3 clinical cases of right HF secondary to TR after PM implantation. In these patients the clinic is right HF, which can appear early, as in our second patient, or after years of implementation of the PM, as in the first and third patients. The diagnosis is confirmed by echocardiography, the most accurate 3D, followed by transesophageal. The 2D transthoracic can not detect it, because it has low sensitivity for TR associated with PM. Medical treatment is always the first choice, since any other procedure carries significant morbidity and mortality. Probably this is a condition that we will diagnose with increasing frequency, because there are more and more patients with devices and, at the same time, the diagnostic tools are improving. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

  8. Flexible supercapacitors

    Institute of Scientific and Technical Information of China (English)

    Shan Shi; Chengjun Xu; Cheng Yang; Jia Li; Hongda Du; Baohua Li; Feiyu Kang

    2013-01-01

    Flexible supercapacitors show a great potential for applications in wearable,miniaturized,portable,largescale transparent and flexible consumer electronics due to their significant,inherent advantages,such as being flexible,lightweight,low cost and environmentally friendly in comparison with the current energy storage devices.In this report,recent progress on flexible supercapacitors,flexible electrodes and electrolytes is reviewed.In addition,the future challenges and opportunities are discussed.

  9. Flexible subunit stoichiometry of functional human P2X2/3 heteromeric receptors.

    Science.gov (United States)

    Kowalski, Maria; Hausmann, Ralf; Schmid, Julia; Dopychai, Anke; Stephan, Gabriele; Tang, Yong; Schmalzing, Günther; Illes, Peter; Rubini, Patrizia

    2015-12-01

    The aim of the present work was to clarify whether heterotrimeric P2X2/3 receptors have a fixed subunit stoichiometry consisting of one P2X2 and two P2X3 subunits as previously suggested, or a flexible stoichiometry containing also the inverse subunit composition. For this purpose we transfected HEK293 cells with P2X2 and P2X3 encoding cDNA at the ratios of 1:2 and 4:1, and analysed the biophysical and pharmacological properties of the generated receptors by means of the whole-cell patch-clamp technique. The concentration-response curves for the selective agonist α,β-meATP did not differ from each other under the two transfection ratios. However, co-expression of an inactive P2X2 mutant and the wild type P2X3 subunit and vice versa resulted in characteristic distortions of the α,β-meATP concentration-response relationships, depending on which subunit was expressed in excess, suggesting that HEK293 cells express mixtures of (P2X2)1/(P2X3)2 and (P2X2)2/(P2X3)1 receptors. Whereas the allosteric modulators H+ and Zn2+ failed to discriminate between the two possible heterotrimeric receptor variants, the α,β-meATP-induced responses were blocked more potently by the competitive antagonist A317491, when the P2X2 subunit was expressed in deficit of the P2X3 subunit. Furthermore, blue-native PAGE analysis of P2X2 and P2X3 subunits co-expressed in Xenopus laevis oocytes and HEK293 cells revealed that plasma membrane-bound P2X2/3 receptors appeared in two clearly distinct heterotrimeric complexes: a (P2X2-GFP)2/(P2X3)1 complex and a (P2X2-GFP)1/(P2X3)2 complex. These data strongly indicate that the stoichiometry of the heteromeric P2X2/3 receptor is not fixed, but determined in a permutational manner by the relative availability of P2X2 and P2X3 subunits.

  10. Piezoelectric energy harvesting from heartbeat vibrations for leadless pacemakers

    Science.gov (United States)

    Ansari, M. H.; Karami, M. Amin

    2015-12-01

    This paper studies energy harvesting from heartbeat vibrations using fan-folded piezoelectric beams. The generated energy from the heartbeat can be used to power a leadless pacemaker. In order to utilize the available 3 dimensional space to the energy harvester, we chose the fan-folded design. The proposed device consists of several piezoelectric beams stacked on top of each other. The size for this energy harvester is 2 cm by 0.5 cm by 1 cm, which makes the natural frequency very high. High natural frequency is one major concern about the micro-scaled energy harvesters. By utilizing the fan-folded geometry and adding tip mass and link mass to the configuration, this natural frequency is reduced to the desired range. This fan-folded design makes it possible to generate more than 10 μW of power. The proposed device does not incorporate magnets and is thus Magnetic resonance imaging (MRI) compatible. Although our device is a linear energy harvester, it is shown that the device is relatively insensitive to the heartrate. The natural frequencies and the mode shapes of the device are calculated. An analytical solution is presented and the method is verified by experimental investigation. We use a closed loop shaker controller and a shaker to simulate the heartbeat vibrations. The developed analytical model is verified through comparison of theoretical and experimental tip displacement and acceleration frequency response functions.

  11. Caffeine increases light responsiveness of the mouse circadian pacemaker.

    Science.gov (United States)

    van Diepen, Hester C; Lucassen, Eliane A; Yasenkov, Roman; Groenen, Inske; Ijzerman, Adriaan P; Meijer, Johanna H; Deboer, Tom

    2014-11-01

    Caffeine is the most commonly used psychoactive stimulant worldwide. It reduces sleep and sleepiness by blocking access to the adenosine receptor. The level of adenosine increases during sleep deprivation, and is thought to induce sleepiness and initiate sleep. Light-induced phase shifts of the rest-activity circadian rhythms are mediated by light-responsive neurons of the suprachiasmatic nucleus (SCN) of the hypothalamus, where the circadian clock of mammals resides. Previous studies have shown that sleep deprivation reduces circadian clock phase-shifting capacity and decreases SCN neuronal activity. In addition, application of adenosine agonists and antagonists mimics and blocks, respectively, the effect of sleep deprivation on light-induced phase shifts in behaviour, suggesting a role for adenosine. In the present study, we examined the role of sleep deprivation in and the effect of caffeine on light responsiveness of the SCN. We performed in vivo electrical activity recordings of the SCN in freely moving mice, and showed that the sustained response to light of SCN neuronal activity was attenuated after 6 h of sleep deprivation prior to light exposure. Subsequent intraperitoneal application of caffeine was able to restore the response to light. Finally, we performed behavioural recordings in constant conditions, and found enhanced period lengthening during chronic treatment with caffeine in drinking water in constant light conditions. The data suggest that increased homeostatic sleep pressure changes circadian pacemaker functioning by reducing SCN neuronal responsiveness to light. The electrophysiological and behavioural data together provide evidence that caffeine enhances clock sensitivity to light.

  12. Impact of retrograde flexible ureteroscopy and intracorporeal lithotripsy on kidney functional outcomes

    Directory of Open Access Journals (Sweden)

    Nicolas Hoarau

    2015-10-01

    Full Text Available ABSTRACT Objective: The aim of the study was to evaluate renal function and to identify factors associated with renal function deterioration after retrograde intrarenal surgery (RIRS for kidney stones. Materials and Methods: We retrospectively analyzed patients with renal stones treated by RIRS between January 2010 and June 2013 at a single institute. We used the National Kidney Foundation classification of chronic kidney disease (CKD to classify Glomerular Filtration Rate (GFR in 5 groups. The baseline creatinine level was systematically pre-operatively and post-operatively evaluated. All patients had a creatinine blood measurement in June 2013. A change toward a less or a more favorable GFR group following RIRS was considered significant. Results: We included 163 patients. There were 86 males (52.8% and 77 females (47.3% with a mean age of 52.8±17 years. After a mean follow-up of 15.5±11.5 months, median GFR was not significantly changed from 84.3±26.2 to 84.9±24.5 mL/min (p=0.675. Significant renal function deterioration occurred in 8 cases (4.9% and significant renal function amelioration occurred in 23 cases (14.1%. In univariate analysis, multiple procedures (p=0.023; HR: 5.4 and preoperative CKD (p=0.011; HR: 6.8 were associated with decreased renal function. In multivariate analysis these factors did not remain as predictive factors. Conclusion: Stone management with RIRS seems to have favorable outcomes on kidney function; however, special attention should be given to patients with multiple procedures and preoperative chronic kidney disease.

  13. Dynamic flexibility in the structure and function of photosystem II in higher plant thylakoid membranes: the grana enigma.

    Science.gov (United States)

    Anderson, Jan M; Chow, Wah Soon; De Las Rivas, Javier

    2008-01-01

    Grana are not essential for photosynthesis, yet they are ubiquitous in higher plants and in the recently evolved Charaphyta algae; hence grana role and its need is still an intriguing enigma. This article discusses how the grana provide integrated and multifaceted functional advantages, by facilitating mechanisms that fine-tune the dynamics of the photosynthetic apparatus, with particular implications for photosystem II (PSII). This dynamic flexibility of photosynthetic membranes is advantageous in plants responding to ever-changing environmental conditions, from darkness or limiting light to saturating light and sustained or intermittent high light. The thylakoid dynamics are brought about by structural and organizational changes at the level of the overall height and number of granal stacks per chloroplast, molecular dynamics within the membrane itself, the partition gap between appressed membranes within stacks, the aqueous lumen encased by the continuous thylakoid membrane network, and even the stroma bathing the thylakoids. The structural and organizational changes of grana stacks in turn are driven by physicochemical forces, including entropy, at work in the chloroplast. In response to light, attractive van der Waals interactions and screening of electrostatic repulsion between appressed grana thylakoids across the partition gap and most probably direct protein interactions across the granal lumen (PSII extrinsic proteins OEEp-OEEp, particularly PsbQ-PsbQ) contribute to the integrity of grana stacks. We propose that both the light-induced contraction of the partition gap and the granal lumen elicit maximisation of entropy in the chloroplast stroma, thereby enhancing carbon fixation and chloroplast protein synthesizing capacity. This spatiotemporal dynamic flexibility in the structure and function of active and inactive PSIIs within grana stacks in higher plant chloroplasts is vital for the optimization of photosynthesis under a wide range of environmental and

  14. Single surgical procedure combining epicardial pacemaker implantation and subsequent extraction of the infected pacing system for pacemaker-dependent patients.

    Science.gov (United States)

    Amraoui, Sana; Barandon, Laurent; Whinnett, Zachary; Ploux, Sylvain; Labrousse, Louis; Denis, Arnaud; Oses, Pierre; Ritter, Philippe; Haissaguerre, Michel; Bordachar, Pierre

    2013-08-01

    Management of pacemaker infection in pacing-dependent patients is often challenging. Typically, temporary pacing is used while antibiotic therapy is given for a number of days before reimplantation of a new endocardial system. This results in a prolonged hospital stay and complications associated with temporary pacing. In this study, we examine the feasibility of performing a single combined procedure of epicardial pacemaker implantation followed by system extraction. One hundred consecutive infected pacemaker-dependent patients underwent implantation of 2 epicardial ventricular leads and were converted to a ventricular demand pacing system. The infected pacing system was then extracted during the same procedure. Patients were followed up for 12 months. Significant pericardial bleeding developed during the procedure in 3 patients. The presence of the pericardial drain positioned during the implantation of the epicardial pacing system meant that cardiac tamponade did not occur, allowing surgical repair with sternotomy to be carried out under stable hemodynamic conditions. Two of these 100 patients died in the 30-day postoperative period; 1 death was due to septic shock and 1 to pulmonary distress. Median 1-year epicardial pacing thresholds were stable and excellent (1.4 ± 0.9 volts). However, 1 of the 2 leads developed increased thresholds in 6 patients, which led to the exclusive use of other ventricular lead. A single combined procedure of surgical epicardial pacemaker implantation and pacemaker system extraction appears to be a safe and effective method for managing pacemaker-dependent patients with infected pacemakers. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  15. Power Control Flexibilities for Grid-Connected Multi-Functional Photovoltaic Inverters

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Wang, Huai

    2016-01-01

    and intelligent services, such as fault ride-through and reactive power compensation, is the key to attain higher utilisation of solar PV energy. Such functionalities for the future PV inverters can contribute to reduced cost of energy, and thus enable more cost-effective PV installations. To implement...

  16. Flexible gateway constructs for functional analyses of genes in plant pathogenic fungi

    NARCIS (Netherlands)

    Mehrabi, Rahim; Mirzadi Gohari, Amir; Silva, da Gilvan Ferreira; Steinberg, Gero; Kema, Gert H.J.; Wit, de Pierre J.G.M.

    2015-01-01

    Genetic manipulation of fungi requires quick, low-cost, efficient, high-throughput and molecular tools. In this paper, we report 22 entry constructs as new molecular tools based on the Gateway technology facilitating rapid construction of binary vectors that can be used for functional analysis of

  17. Patients exposure from fluoroscopic guided pacemaker implantation procedures

    Energy Technology Data Exchange (ETDEWEB)

    Alkhorayef, M.; Babikir, E. [King Saud University, College of Applied Sciences, Radiological Sciences Department, P. O. Box 10219, Riyadh 11433 (Saudi Arabia); Sulieman, A. [Prince Sattam bin Abdulaziz University, College of Applied Medical Sciences, Radiology and Medical Imaging Department, P. O. Box 422, Alkharj 11942 (Saudi Arabia); Daar, E. [University of Jordan, Faculty of Science, Department of Physics, Amman 11942 (Jordan); Alnaaimi, M.; Alduaij, M. [Kuwait Cancer Control Centre, Department of Nuclear Medicine, Shwiekh (Kuwait); Bradley, D., E-mail: malkhorayef@ksu.edu.sa [University of Surrey, Centre for Nuclear and Radiation Physics, Guildford, Surrey, GU2 7XH (United Kingdom)

    2016-10-15

    A pacemaker, which is used for heart re synchronization with electrical impulses, is used to manage many clinical conditions. Recently, the frequency of the pacemaker implantation procedures increased 50% worldwide. During this procedure, patients and staff can be exposed to excessive radiation exposure. Wide range of doses was reported in previous studies, suggesting that optimization of this procedure is not fulfilled yet. This study aims to evaluate the patient and staff radiation doses during cardiac pacemaker procedure and quantify the patient effective dose. A total of 145 procedures were performed for five pacemakers procedures (VVI, VVIR, VVD, VVDR and DDDR) two hospitals were evaluated. Patients doses were measured using the kerma-area product meter. Effective doses were estimated using software based on Monte Carlo simulation from National Radiological Protection Board. The effective dose values were used to estimate the cancer risk from pacemaker procedure. Patients demographic data, exposure parameters for both fluoroscopy and radiography were quantified. The mean patients doses (Gy. cm{sup 2}) for VVI, VVIR, VVD, VVDR and DDDR was 1.52±0.13 (1.43-1.61), 3.28±2.34 (0.29-8.73), 3.04±1.67 (1.57-4.86), 6.04±2.326 and 19.2±3.6 (5.43-30.2), respectively, per procedure. The overall patients effective dose is 1.1 mSv per procedure. (Author)

  18. Dual chamber pacemaker in the treatment of paroxysmal atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Rađen Goran

    2005-01-01

    Full Text Available Background. Atrial fibrillation is the most frequent cardiac dysrhythmia. The aim of this study was to show the role and the efficacy of a dual chamber pacemaker with the algorithm of atrial dynamic overdrive, in the suppression of paroxysmal atrial fibrillation. Case report. A woman with a classical bradycardia-tachycardia syndrome, and frequent attacks of atrial fibrillation, underwent the implantation of a single chamber permanent pacemaker (VVI. Pacemaker successfully treated the episodes of symptomatic bradycardia, but the patient had frequent attacks of atrial fibrillation, despite the use of different antiarrhythmic drugs, which she did not tolerate well. The decision was made to reimplant a permanent dual chamber pacemaker with the algorithm of atrial dynamic overdrive. The pacemaker was programmed to the basic rate of 75/min, while rate at rest was 55/min. In addition, sotalol was administered. After three months, the patient became asymptomatic with only 4 short − term episodes of atrial fibrillation, and a high level of atrial pacing (99%. Conclusion. In selected patients with bradycardia−tachycardia syndrome, atrial-based pacing seemed to be very effective in reducing the incidence of paroxysmal atrial fibrillation.

  19. Implantable Cardiac Pacemakers – 50 Years from the First Implantation

    Directory of Open Access Journals (Sweden)

    Ratko Magjarević

    2010-01-01

    Overview: Development of implantable cardiac pacemaker was enabled by another important invention, the silicon transistor. h ough the invention of suitable lithium cells as appropriate power supply was essential for prolongation of battery life cycle and for increased reliability of pacemakers, main milestones in the development were associated with technological breakthroughs in electronics: from transistors, which introduced such features as small size and low power consumption, to hybrid and integrated circuits, which enabled programmability, microprocessors, which added more options in programming (multiprogrammability, diagnostics and telemetry, and the ICT (information communication technology that enabled physicians remote access to patients and interrogation of their implantable devices. Conclusions: Implantable pacemakers are reliable devices indicated for a wide range of dif erent therapies of cardiac rhythm disorders and heart failure. h ere is still a lot to learn about the physiology of a normal heart and even more about the failing heart. Modern pacemakers provide physicians valuable information from pacemakers’ memory via the built-in telemetry system. h ese information help physicians to better understand pathologic processes within the heart, thus contributing to the development of new ideas for treatment of diseases and for precise tailoring of the therapy to the patient’s needs. Although implantable pacemakers have reached the level of mature technology, they will continue to develop with therapies and diagnostics to facilitate a higher quality of life.

  20. Pacemaker pocket infection due to Mycobacterium goodii, a rapidly growing mycobacteria.

    Science.gov (United States)

    Yoo, David K; Hosseini-Moghaddam, Seyed M

    2017-01-10

    A woman aged 74 years with an implanted dual-chamber pacemaker presented with pacemaker site infection after failing empiric antimicrobial therapy. The pathogen was later identified as Mycobacterium goodii, a rapidly growing mycobacteria species. The pacemaker was subsequently removed and the patient was treated with oral ciprofloxacin and doxycycline with clinical improvement. In this article, we describe a rare case of pacemaker site infection by M. goodii. 2017 BMJ Publishing Group Ltd.

  1. Surgical Removal of a Giant Vegetation on Permanent Endocavitary Pacemaker Wire and Lead

    Institute of Scientific and Technical Information of China (English)

    Guo-tao Ma; Qi Miao; Chao-ji Zhang; Li-hua Cao

    2011-01-01

    PACEMAKER lead infections are rare.There are only about 0.4%-1.1% of the patients who have been implanted permanent pacemakers suffering from serious infections which lead to endocarditis.1 Generally,removal of the infected pacemaker wire and lead,long-term anti-infection therapy,and implantation of a new pacemaker to another anatomic site are accepted approaches for these patients.

  2. Power control flexibilities for grid-connected multi-functional photovoltaic inverters

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Wang, Huai

    2014-01-01

    This paper explores the next-generation Photo- Voltaic (PV) system integration issues at a high penetration level, where the grid is becoming more decentralized and vulnerable. Therefore, the PV systems are expected to be more controllable with higher efficiency and higher reliability. Provision...... to generate appropriate references for the inner current control loop. The references depend on the system conditions and also specific demands from both system operators and customers. Besides, this power control strategy can be implemented in a commercial PV inverter as standardized functions, and also...

  3. Nonlinear Strain Measures, Shape Functions and Beam Elements for Dynamics of Flexible Beams

    Energy Technology Data Exchange (ETDEWEB)

    Sharf, I. [University of Victoria, Department of Mechanical Engineering (Canada)

    1999-05-15

    In this paper, we examine several aspects of the development of an explicit geometrically nonlinear beam element. These are: (i) linearization of the displacement field; (ii) the effect of a commonly adopted approximation for the nonlinear Lagrangian strain; and (iii) use of different-order shape functions for discretization. The issue of rigid-body check for a nonlinear beam element is also considered. An approximate check is introduced for an element based on an (approximate) intermediate strain measure. Several numerical examples are presented to support the analysis. The paper concludes with a discussion on the use of explicit nonlinear beam elements for multibody dynamics simulation.

  4. Functionalization of nanomaterials by non-thermal large area atmospheric pressure plasmas: application to flexible dye-sensitized solar cells

    Science.gov (United States)

    Jung, Heesoo; Park, Jaeyoung; Yoo, Eun Sang; Han, Gill-Sang; Jung, Hyun Suk; Ko, Min Jae; Park, Sanghoo; Choe, Wonho

    2013-08-01

    A key challenge to the industrial application of nanotechnology is the development of fabrication processes for functional devices based on nanomaterials which can be scaled up for mass production. In this report, we disclose the results of non-thermal radio-frequency (rf) atmospheric pressure plasma (APP) based deposition of TiO2 nanoparticles on a flexible substrate for the fabrication of dye-sensitized solar cells (DSSCs). Operating at 190 °C without a vacuum enclosure, the APP method can avoid thermal damage and vacuum compatibility restrictions and utilize roll-to-roll processing over a large area. The various analyses of the TiO2 films demonstrate that superior film properties can be obtained by the non-thermal APP method when compared with the thermal sintering process operating at 450 °C. The crystallinity of the anatase TiO2 nanoparticles is significantly improved without thermal agglomeration, while the surface defects such as Ti3+ ions are eliminated, thus providing efficient charge collecting properties for solar cells. Finally, we successfully fabricated a flexible DSSC with an energy conversion efficiency of 4.2% using a transparent plastic substrate. This work demonstrates the potential of non-thermal APP technology in the area of device-level, nano-enabled material manufacturing.A key challenge to the industrial application of nanotechnology is the development of fabrication processes for functional devices based on nanomaterials which can be scaled up for mass production. In this report, we disclose the results of non-thermal radio-frequency (rf) atmospheric pressure plasma (APP) based deposition of TiO2 nanoparticles on a flexible substrate for the fabrication of dye-sensitized solar cells (DSSCs). Operating at 190 °C without a vacuum enclosure, the APP method can avoid thermal damage and vacuum compatibility restrictions and utilize roll-to-roll processing over a large area. The various analyses of the TiO2 films demonstrate that superior film

  5. 77 FR 37573 - Effective Date of Requirement for Premarket Approval for an Implantable Pacemaker Pulse Generator

    Science.gov (United States)

    2012-06-22

    ... Approval for an Implantable Pacemaker Pulse Generator AGENCY: Food and Drug Administration, HHS. ACTION... protocol (PDP) for implantable pacemaker pulse generators. The Agency has summarized its findings regarding... PMA or notice of completion of a PDP for the implantable pacemaker pulse generator. In accordance...

  6. SYNCHRONIZATION OF TWO COUPLED HINDMARSH-ROSE NEURONS BY A PACEMAKER

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    This paper considers the synchronization of two coupled Hindmarsh-Rose neurons by a pacemaker.Based on the stability theory of differential equations,the complete synchronization of this pacemaker neuron model is reached.Moreover,we also show that pacemaker can enhance or induce synchronization.Numerical simulations are given to illustrate the main results.

  7. Pacemaker Dependency after Cardiac Surgery: A Systematic Review of Current Evidence.

    Science.gov (United States)

    Steyers, Curtis M; Khera, Rohan; Bhave, Prashant

    2015-01-01

    Severe postoperative conduction disturbances requiring permanent pacemaker implantation frequently occur following cardiac surgery. Little is known about the long-term pacing requirements and risk factors for pacemaker dependency in this population. We performed a systematic review of the literature addressing rates and predictors of pacemaker dependency in patients requiring permanent pacemaker implantation after cardiac surgery. Using a comprehensive search of the Medline, Web of Science and EMBASE databases, studies were selected for review based on predetermined inclusion and exclusion criteria. A total of 8 studies addressing the endpoint of pacemaker-dependency were identified, while 3 studies were found that addressed the recovery of atrioventricular (AV) conduction endpoint. There were 10 unique studies with a total of 780 patients. Mean follow-up ranged from 6-72 months. Pacemaker dependency rates ranged from 32%-91% and recovery of AV conduction ranged from 16%-42%. There was significant heterogeneity with respect to the definition of pacemaker dependency. Several patient and procedure-specific variables were found to be independently associated with pacemaker dependency, but these were not consistent between studies. Pacemaker dependency following cardiac surgery occurs with variable frequency. While individual studies have identified various perioperative risk factors for pacemaker dependency and non-resolution of AV conduction disease, results have been inconsistent. Well-conducted studies using a uniform definition of pacemaker dependency might identify patients who will benefit most from early permanent pacemaker implantation after cardiac surgery.

  8. 77 FR 39924 - Effective Date of Requirement for Premarket Approval for Cardiovascular Permanent Pacemaker...

    Science.gov (United States)

    2012-07-06

    ... Approval for Cardiovascular Permanent Pacemaker Electrode AGENCY: Food and Drug Administration, HHS. ACTION... protocol (PDP) for the cardiovascular permanent pacemaker electrode. The Agency has summarized its findings... cardiovascular permanent pacemaker electrode. In accordance with section 515(b)(2)(A) of the FD&C Act, FDA...

  9. [TRENDS OF PERMANENT PACEMAKER IMPLANTATION IN A SINGLE CENTER OVER A 20-YEAR PERIOD].

    Science.gov (United States)

    Antonelli, Dante; Ilan, Limor Bushar; Freedberg, Nahum A; Feldman, Alexander; Turgeman, Yoav

    2015-05-01

    To review the changes in permanent pacemaker implantation indications, pacing modes and patients' demographics over a 20-year period. We retrospectively retrieved data on patients who underwent first implantation of the pacemaker between 1-1-1991 and 31-12-2010. One thousand and nine (1,009) patients underwent a first pacemaker implantation during that period; 535 were men (53%), their mean age was 74.6±19.5 years; the highest rate of implanted pacemaker was in patients ranging in age from 70-79 years, however there was an increasing number of patients aged over 80 years. The median survival time after initial pacemaker implantation was 8 years. Syncope was the most common symptom (62.5%) and atrioventricular block was the most common electrocardiographic indication (56.4%) leading to pacemaker implantation. There was increased utilization of dual chamber and rate responsive pacemakers over the years. There was no difference regarding mode selection between genders. Pacemaker implantation rates have increased over a 20-year period. Dual chamber replaced most of the single ventricular chamber pacemaker and rate responsive pacemakers became the norm. The data of a small volume center are similar to those reported in pacemaker surveys of high volume pacemaker implantation centers. They confirm adherence to the published guidelines for pacing.

  10. [Use of percutaneous anesthesia in cardiac pacemaker implantation].

    Science.gov (United States)

    Trigano, J A; Paganelli, F; Taramasco, V; Levy, S; Lorec, A M; Blin, O; Bruguerolle, B

    Assess the efficacy of an anesthesic cream for pacemaker implantations. Percutaneous anesthesia was studied in a series of permanent pacemaker transvenous implantations. The anesthesic cream composed of a mixture of lidocaine and prilocaine was applied precisely over operative areas after marking the skin. Percutaneous anesthesia should be applied 2 hours before entering the operating room. This percutaneous local anesthesia was perfectly effective for simple replacement procedures. At first implantations, it was used alone in 4 out of 10 cases while intradermal injections were needed to anesthetize the deep layers in the other patients. Serum concentrations indicate very low levels which are tolerated very well. Alone or combined with lidocaine infiltration, the use of an anesthesic cream is safe and effective in transvenous pacemaker surgery.

  11. TASER conducted electrical weapons and implanted pacemakers and defibrillators.

    Science.gov (United States)

    Vanga, Subba R; Bommana, Sudharani; Kroll, Mark W; Swerdlow, Charles; Lakkireddy, Dhanunjaya

    2009-01-01

    Conducted electrical weapons (CEW) have generated controversy in recent years regarding their effect on heart rhythm and on their suspected interaction with implanted devices such as the pacemakers and ICDs (implantable cardioverter defibrillators). We review the current evidence available on device interactions and pre-sent a new case series of 6 patients. We used the available case reports and animal studies on TASER or CEW related publications in PubMed. Oversensing of TASER CEW discharges may cause noise reversion pacing in pacemakers and inappropriate detection of VF in ICDs. The nominal 5-second discharge is sufficiently short that neither clinically significant inhibition of bradycardia pacing nor inappropriate ICD shocks have been reported. Current evidence indicates that CEW discharges do not have adverse effects on pacemakers and ICDs.

  12. Efficient estimation and prediction for the Bayesian binary spatial model with flexible link functions.

    Science.gov (United States)

    Roy, Vivekananda; Evangelou, Evangelos; Zhu, Zhengyuan

    2016-03-01

    Spatial generalized linear mixed models (SGLMMs) are popular models for spatial data with a non-Gaussian response. Binomial SGLMMs with logit or probit link functions are often used to model spatially dependent binomial random variables. It is known that for independent binomial data, the robit regression model provides a more robust (against extreme observations) alternative to the more popular logistic and probit models. In this article, we introduce a Bayesian spatial robit model for spatially dependent binomial data. Since constructing a meaningful prior on the link function parameter as well as the spatial correlation parameters in SGLMMs is difficult, we propose an empirical Bayes (EB) approach for the estimation of these parameters as well as for the prediction of the random effects. The EB methodology is implemented by efficient importance sampling methods based on Markov chain Monte Carlo (MCMC) algorithms. Our simulation study shows that the robit model is robust against model misspecification, and our EB method results in estimates with less bias than full Bayesian (FB) analysis. The methodology is applied to a Celastrus Orbiculatus data, and a Rhizoctonia root data. For the former, which is known to contain outlying observations, the robit model is shown to do better for predicting the spatial distribution of an invasive species. For the latter, our approach is doing as well as the classical models for predicting the disease severity for a root disease, as the probit link is shown to be appropriate. Though this article is written for Binomial SGLMMs for brevity, the EB methodology is more general and can be applied to other types of SGLMMs. In the accompanying R package geoBayes, implementations for other SGLMMs such as Poisson and Gamma SGLMMs are provided.

  13. Experimental evidence of a chaotic region in a neural pacemaker

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Hua-Guang, E-mail: guhuaguang@tongji.edu.cn [School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092 (China); Department of Electronic Engineering, City University of Hong Kong, Hong Kong SAR (China); Jia, Bing [School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092 (China); Chen, Guan-Rong [Department of Electronic Engineering, City University of Hong Kong, Hong Kong SAR (China)

    2013-03-15

    In this Letter, we report the finding of period-adding scenarios with chaos in firing patterns, observed in biological experiments on a neural pacemaker, with fixed extra-cellular potassium concentration at different levels and taken extra-cellular calcium concentration as the bifurcation parameter. The experimental bifurcations in the two-dimensional parameter space demonstrate the existence of a chaotic region interwoven with the periodic region thereby forming a period-adding sequence with chaos. The behavior of the pacemaker in this region is qualitatively similar to that of the Hindmarsh–Rose neuron model in a well-known comb-shaped chaotic region in two-dimensional parameter spaces.

  14. Successful management of late right ventricular perforation after pacemaker implantation

    Directory of Open Access Journals (Sweden)

    Amir K Bigdeli

    2010-01-01

    Full Text Available Amir K Bigdeli1, Andres Beiras-Fernandez1, Ingo Kaczmarek1, Christian Kowalski2, Michael Schmoeckel1, Bruno Reichart11Department of Cardiac Surgery, 2Department of Anesthesiology, Ludwig-Maximilians University, Munich, GermanyAbstract: Complications of pacemaker implantation include myocardial perforation, venous thrombosis, vegetations of the tricuspid valve or pacing lead, and tricuspid regurgitation. We report a patient presenting with a case of delayed ventricular lead perforation through the right ventricle. The lead was uneventfully extracted under transesophageal echocardiographic observation in the operating room with cardiac surgery backup.Keywords: pacemaker, lead perforation, complication

  15. Raf kinase inhibitory protein function is regulated via a flexible pocket and novel phosphorylation-dependent mechanism.

    Science.gov (United States)

    Granovsky, Alexey E; Clark, Matthew C; McElheny, Dan; Heil, Gary; Hong, Jia; Liu, Xuedong; Kim, Youngchang; Joachimiak, Grazyna; Joachimiak, Andrzej; Koide, Shohei; Rosner, Marsha Rich

    2009-03-01

    Raf kinase inhibitory protein (RKIP/PEBP1), a member of the phosphatidylethanolamine binding protein family that possesses a conserved ligand-binding pocket, negatively regulates the mammalian mitogen-activated protein kinase (MAPK) signaling cascade. Mutation of a conserved site (P74L) within the pocket leads to a loss or switch in the function of yeast or plant RKIP homologues. However, the mechanism by which the pocket influences RKIP function is unknown. Here we show that the pocket integrates two regulatory signals, phosphorylation and ligand binding, to control RKIP inhibition of Raf-1. RKIP association with Raf-1 is prevented by RKIP phosphorylation at S153. The P74L mutation increases kinase interaction and RKIP phosphorylation, enhancing Raf-1/MAPK signaling. Conversely, ligand binding to the RKIP pocket inhibits kinase interaction and RKIP phosphorylation by a noncompetitive mechanism. Additionally, ligand binding blocks RKIP association with Raf-1. Nuclear magnetic resonance studies reveal that the pocket is highly dynamic, rationalizing its capacity to interact with distinct partners and be involved in allosteric regulation. Our results show that RKIP uses a flexible pocket to integrate ligand binding- and phosphorylation-dependent interactions and to modulate the MAPK signaling pathway. This mechanism is an example of an emerging theme involving the regulation of signaling proteins and their interaction with effectors at the level of protein dynamics.

  16. Strategic flexibility

    OpenAIRE

    Kim, KiHyung

    2014-01-01

    A flexible system is defined as one that can change the entity's stance, capability or status reacting to a change of the entity's environment. Flexibility has gathered the attention of academic researchers and industry practitioners as an efficient approach to cope with today's volatile environment. As the environments become more unpredictable and volatile, it is imperative for a flexible system to respond quickly to a change in its circumstance. How much flexibility is embedded into the sy...

  17. Apical Ballooning Syndrome (Takotsubo Cardiomyopathy after Permanent Dual-Chamber Pacemaker Implantation

    Directory of Open Access Journals (Sweden)

    Armando Gardini

    2012-01-01

    Full Text Available Apical ballooning syndrome, also called takotsubo cardiomyopathy, has been recently reported. It may mimic acute myocardial infarction and is typically observed in postmenopausal women after stressful events. A 75-year-old female after permanent dual chamber pacemaker implant complained of chest pain with repolarization alterations suggesting acute myocardial ischemia. Echocardiography showed a left ventricle with akinesia of the apical portions and reduced global systolic function. The patient was treated with antithrombotic agents and intravenous nitrates. No coronary lesions were found at angiography. At ventriculography, a typical takotsubo-like shape of the left ventricle was observed. The clinical and echocardiographic picture normalized at discharge.

  18. Venous Obstruction Following Pacemaker or Implantable Cardioverter-Defibrillator Implantation, Mini Review

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Akbarzadeh

    2016-08-01

    Full Text Available Venous obstruction is relatively frequent following permanent pacemaker or implantable cardioverter-defibrillator (ICD implantation. However, most of them are asymptomatic. Although the exact risk factor for this complication is not known, number of leads, heart failure and infection may prone the patient to this complication. The goal standard for detection of vein stenosis is venography; however, ultrasound sonography has an acceptable accuracy. Anticoagulant therapy may be considered for symptomatic patients. For device upgrading, non-functional leads removal, venoplasty and rarely surgical treatment may be indicated.

  19. Functional maintenance and structural flexibility of microbial communities perturbed by simulated intense rainfall in a pilot-scale membrane bioreactor.

    Science.gov (United States)

    Sato, Yuya; Hori, Tomoyuki; Navarro, Ronald R; Habe, Hiroshi; Ogata, Atsushi

    2016-07-01

    Intense rainfall is one of the most serious and common natural events, causing the excessive inflow of rainwater into wastewater treatment plants. However, little is known about the impacts of rainwater dilution on the structure and function of the sludge microorganisms. Here, high-throughput sequencing of 16S ribosomal RNA (rRNA) genes was implemented to describe the microbial community dynamics during the simulated intense rainfall situation (event i) in which approximately 45 % of the sludge biomass was artificially overflowed by massive water supply in a pilot-scale membrane bioreactor. Thereafter, we investigated the functional and structural responses of the perturbed microbial communities to subsequent conditional changes, i.e., an increase in organic loading rate from 225 to 450 mg chemical oxygen demand (COD) l(-1) day(-1) (event ii) and an addition of a microbiota activator (event iii). Due to the event i, the COD removal declined to 78.2 %. This deterioration coincided with the decreased microbial diversity and the proliferation of the oligotrophic Aquabacterium sp. During the succeeding events ii and iii, the sludge biomass increased and the COD removal became higher (86.5-97.4 %). With the apparent recovery of the reactor performance, microbial communities became diversified and the compositions dynamically changed. Notably, various bacterial micropredators were highly enriched under the successive conditions, most likely being involved in the flexible reorganization of microbial communities. These results indicate that the activated sludge harbored functionally redundant microorganisms that were able to thrive and proliferate along with the conditional changes, thereby contributing to the functional maintenance of the membrane bioreactor.

  20. Flexible Ablators

    Science.gov (United States)

    Stackpoole, Margaret M. (Inventor); Ghandehari, Ehson M. (Inventor); Thornton, Jeremy J. (Inventor); Covington, Melmoth Alan (Inventor)

    2017-01-01

    A low-density article comprising a flexible substrate and a pyrolizable material impregnated therein, methods of preparing, and devices using the article are disclosed. The pyrolizable material pyrolizes above 350 C and does not flow at temperatures below the pyrolysis temperature. The low-density article remains flexible after impregnation and continues to remain flexible when the pyrolizable material is fully pyrolized.

  1. Flexible Word Classes

    DEFF Research Database (Denmark)

    2013-01-01

    • First major publication on the phenomenon • Offers cross-linguistic, descriptive, and diverse theoretical approaches • Includes analysis of data from different language families and from lesser studied languages This book is the first major cross-linguistic study of 'flexible words', i.e. words...... that cannot be classified in terms of the traditional lexical categories Verb, Noun, Adjective or Adverb. Flexible words can - without special morphosyntactic marking - serve in functions for which other languages must employ members of two or more of the four traditional, 'specialised' word classes. Thus......, flexible words are underspecified for communicative functions like 'predicating' (verbal function), 'referring' (nominal function) or 'modifying' (a function typically associated with adjectives and e.g. manner adverbs). Even though linguists have been aware of flexible world classes for more than...

  2. Overcoming functional impairment in postpartum depressed or anxious women: a pilot trial of desvenlafaxine with flexible dosing

    Science.gov (United States)

    Misri, Shaila; Swift, Elena; Abizadeh, Jasmin; Shankar, Radhika

    2016-01-01

    Objectives: Antidepressants are the first line treatment for moderate to severe major depressive disorder (MDD) in perinatal and general populations. However, there appears to be paucity of evidence around antidepressant use in women with postpartum depression or anxiety. Selection of an appropriate antidepressant is crucial in promoting efficacy, optimizing tolerability, and managing comorbid anxiety or depression. Our aim was to investigate the treatment effect and tolerability profile of desvenlafaxine, and to examine the functionality of women with postpartum depression or anxiety after desvenlafaxine treatment. Methods: Fifteen postpartum women with depression or anxiety completed this 12-week prospective pilot study with a flexible dose of desvenlafaxine (50–100 mg). Participants were recruited at a tertiary care level program. Measures of depression (Montgomery–Åsberg Depression Rating Scale, MADRS), anxiety (Hamilton Anxiety Rating Scale, HAM-A), worry (Penn State Worry Questionnaire, PSWQ) and functional impairment (Sheehan Disability Scale, SDS) were completed at baseline, 8 weeks, and 12 weeks. Results: In the intention-to-treat analysis (n = 17), the majority of women responded to medication (88.2%, n = 15), and reached remission of depressive (82.4%, n = 14) and anxiety symptoms (82.4%, n = 14). Remission of depression was achieved in a mean of 6.9 weeks [standard deviation (SD) = 3.01] at a mean dose of 71 mg/day (SD = 25.7). Significant decreases were observed on PSWQ worry scores (p < 0.0001) and SDS scores for social (p < 0.0001) and family life impairment (p < 0.0001). The medication was generally well tolerated. Conclusion: The results of our prospective pilot study suggest that treatment with desvenlafaxine of postpartum mothers with depression or anxiety can lead to symptom remission and restoration of functionality. PMID:27536346

  3. Calsequestrin 2 deletion causes sinoatrial node dysfunction and atrial arrhythmias associated with altered sarcoplasmic reticulum calcium cycling and degenerative fibrosis within the mouse atrial pacemaker complex1

    Science.gov (United States)

    Glukhov, Alexey V.; Kalyanasundaram, Anuradha; Lou, Qing; Hage, Lori T.; Hansen, Brian J.; Belevych, Andriy E.; Mohler, Peter J.; Knollmann, Björn C.; Periasamy, Muthu; Györke, Sandor; Fedorov, Vadim V.

    2015-01-01

    Aims Loss-of-function mutations in Calsequestrin 2 (CASQ2) are associated with catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT patients also exhibit bradycardia and atrial arrhythmias for which the underlying mechanism remains unknown. We aimed to study the sinoatrial node (SAN) dysfunction due to loss of CASQ2. Methods and results In vivo electrocardiogram (ECG) monitoring, in vitro high-resolution optical mapping, confocal imaging of intracellular Ca2+ cycling, and 3D atrial immunohistology were performed in wild-type (WT) and Casq2 null (Casq2−/−) mice. Casq2−/− mice exhibited bradycardia, SAN conduction abnormalities, and beat-to-beat heart rate variability due to enhanced atrial ectopic activity both at baseline and with autonomic stimulation. Loss of CASQ2 increased fibrosis within the pacemaker complex, depressed primary SAN activity, and conduction, but enhanced atrial ectopic activity and atrial fibrillation (AF) associated with macro- and micro-reentry during autonomic stimulation. In SAN myocytes, CASQ2 deficiency induced perturbations in intracellular Ca2+ cycling, including abnormal Ca2+ release, periods of significantly elevated diastolic Ca2+ levels leading to pauses and unstable pacemaker rate. Importantly, Ca2+ cycling dysfunction occurred not only at the SAN cellular level but was also globally manifested as an increased delay between action potential (AP) and Ca2+ transient upstrokes throughout the atrial pacemaker complex. Conclusions Loss of CASQ2 causes abnormal sarcoplasmic reticulum Ca2+ release and selective interstitial fibrosis in the atrial pacemaker complex, which disrupt SAN pacemaking but enhance latent pacemaker activity, create conduction abnormalities and increase susceptibility to AF. These functional and extensive structural alterations could contribute to SAN dysfunction as well as AF in CPVT patients. PMID:24216388

  4. Flexible Software for Flexible Scheduling

    Science.gov (United States)

    Economou, Frossie; Jenness, Tim; Tilanus, Remo P. J.; Hirst, Paul; Adamson, Andy J.; Rippa, Mathew; Delorey, Kynan K.; Isaak, Kate G.

    The JAC Observation Management Project (OMP) provides software for the James Clerk Maxwell (JCMT) and the United Kingdom Infrared (UKIRT) telescopes that manages the life-cycle of flexibly scheduled observations. Its aim is to increase observatory efficiency under flexible (queue) scheduled observing, without depriving the principal investigator (PI) of the flexibility associated with classical scheduling.

  5. Hardware-in-the-loop simulation and energy optimization of cardiac pacemakers.

    Science.gov (United States)

    Barker, Chris; Kwiatkowska, Marta; Mereacre, Alexandru; Paoletti, Nicola; Patane, Andrea

    2015-01-01

    Implantable cardiac pacemakers are medical devices that can monitor and correct abnormal heart rhythms. To provide the necessary safety assurance for pacemaker software, both testing and verification of the code, as well as testing the entire pacemaker hardware in the loop, is necessary. In this paper, we present a hardware testbed that enables detailed hardware-in-the-loop simulation and energy optimisation of pacemaker algorithms with respect to a heart model. Both the heart and the pacemaker models are encoded in Simulink/Stateflow™ and translated into executable code, with the pacemaker executed directly on the microcontroller. We evaluate the usefulness of the testbed by developing a parameter synthesis algorithm which optimises the timing parameters based on power measurements acquired in real-time. The experiments performed on real measurements successfully demonstrate that the testbed is capable of energy minimisation in real-time and obtains safe pacemaker timing parameters.

  6. Pacemaker dislocation - Truly ectopic activation necessitating surgical treatment

    NARCIS (Netherlands)

    de Kroon, TL; Witsenburg, M; Bogerts, AJJC

    2002-01-01

    Intra-abdominal migration of a generator from an epicardial pacemaker system is a rare but potentially life-threatening complication. We report on a case of a 2-year-old child in whom the generator silently migrated from the sheath of the rectus abdominis muscle in the upper abdominal wall down into

  7. [Aspergillus fumigatus endocarditis in a patient with a biventricular pacemaker].

    Science.gov (United States)

    Cuesta, José M; Fariñas, María C; Rodilla, Irene G; Salesa, Ricardo; de Berrazueta, José R

    2005-05-01

    Aspergillus fumigatus endocarditis is one of the rarest and severest complications in cardiological patients. We describe a patient with an intracardial pacemaker who was diagnosed as having Aspergillus fumigatus endocarditis. Postmortem examination showed a large, Aspergillus-infected thrombus encased in the right ventricle, pulmonary trunk and main pulmonary branches.

  8. Apical Ballooning Syndrome: A Complication of Dual Chamber Pacemaker Implantation

    Science.gov (United States)

    Abu Sham'a, Raed A. H; Asher, Elad; Luria, David; Berger, Michael; Glikson, Michael

    2009-01-01

    Apical ballooning is a cardiac syndrome (Takotsubo Cardiomyopathy) described as a typical form of acute transient left ventricular dysfunction. While its onset has often been associated with emotionally or physically stressful situations, it has an overall favorable prognosis. We describe here a case of transient apical ballooning following permanent pacemaker implantation. PMID:19652736

  9. Pacemaker dislocation - Truly ectopic activation necessitating surgical treatment

    NARCIS (Netherlands)

    de Kroon, TL; Witsenburg, M; Bogerts, AJJC

    2002-01-01

    Intra-abdominal migration of a generator from an epicardial pacemaker system is a rare but potentially life-threatening complication. We report on a case of a 2-year-old child in whom the generator silently migrated from the sheath of the rectus abdominis muscle in the upper abdominal wall down into

  10. Pacemaker Related Infective Endocarditis from Staphylococcus Lugdunensis: A Case Report

    Directory of Open Access Journals (Sweden)

    Michael Ward

    2013-01-01

    Full Text Available Staphylococcus lugdunensis is a common skin flora not typically associated with infection. There are, however, several cases reported in the literature of Staphylococcus lugdunensis as a causative bacterium of various infections. This paper reports an additional case of pacemaker associated endocarditis with Staphylococcus lugdunensis as the causative bacterium.

  11. Surgical Repair of Subacute Right Ventricular Perforation after Pacemaker Implantation

    Directory of Open Access Journals (Sweden)

    Takeshi Oda

    2017-01-01

    Full Text Available We report an 84-year-old woman who presented with right ventricular perforation 4 days after pacemaker implantation for syncope due to sick sinus syndrome. Median sternotomy revealed no pericardial effusion, but the pacing lead had penetrated the right ventricle and pericardium. When the pleura was opened, the tip of the lead was seen in the visceral pleura. The lead was cut in the pericardial cavity and extracted from the left subclavian wound together with the generator. The right ventricular perforation was sutured and a temporary pacing lead was placed on the right ventricular wall intraoperatively. Ten days after the surgery, a new pacemaker lead was placed in the ventricular septum via the right axillary vein. Right ventricular perforation is a rare complication after pacemaker implantation. Typically, it occurs at the time of implantation or within 24 hours after implantation. In the present case, the perforation of the right ventricle which needed urgent surgery occurred 4 days after implanting the pacing lead at the right ventricular apex. Great care should have been taken not to overlook this life-threatening complication even more than 24 hours after pacemaker implantation.

  12. Association of creative achievement with cognitive flexibility by a combined voxel-based morphometry and resting-state functional connectivity study.

    Science.gov (United States)

    Chen, Qunlin; Yang, Wenjing; Li, Wenfu; Wei, Dongtao; Li, Haijiang; Lei, Qiao; Zhang, Qinglin; Qiu, Jiang

    2014-11-15

    Although researchers generally concur that creativity involves the production of novel and useful products, the neural basis of creativity remains elusive due to the complexity of the cognitive processes involved. Recent studies have shown that highly creative individuals displayed more cognitive flexibility. However, direct evidence supporting the relationship between creativity and cognitive flexibility has rarely been investigated using both structural and functional neuroimaging techniques. We used a combined voxel-based morphometry and resting-state functional connectivity (rsFC) analysis to investigate the relationship between individual creativity ability assessed by the creative achievement questionnaire (CAQ), and regional gray matter volume (GMV), as well as intrinsic functional connectivity. Results showed that CAQ scores negatively correlated with GMV in the rostral anterior cingulate cortex (ACC) and the bilateral dorsal ACC (dACC) extending to supplementary motor area, but positively correlated with GMV in the bilateral superior frontal gyrus and ventral medial prefrontal cortex (vmPFC). Further functional connectivity analysis revealed that higher creative achievement was inversely associated with the strength of rsFC between the dACC and medial superior frontal gyrus (mSFG), right middle frontal gyrus, and left orbito-frontal insula. Moreover, the association between the dACC-mSFG connectivity and CAQ scores was mediated by cognitive flexibility, assessed by a task-switching paradigm. These findings indicate that individual differences in creative achievement are associated with both brain structure and corresponding intrinsic functional connectivity involved in cognitive flexibility and deliberate creative processing. Furthermore, dACC-mSFG connectivity may affect creative achievement through its impact on cognitive flexibility.

  13. Treatment of class II and class III maloccolusion by using churro jumper: an efficient, inexpensive and uncomplicated fixed flexible functional technique

    OpenAIRE

    Mani, Shubhangi Amit; Mote, Nilesh; Pawar, Kunal Dilip; Mishra, Prashantkumar; Mishra, Richa Anil; Rai, Rajlaxmi Rajaram

    2016-01-01

    Functional orthopedic treatment seeks to improve skeletal and dental relationship of the jaws. The challenging task is to correctly position jaws antero-posteriorly and vertically with correct overbite, overjet and Centric relation. The Churro Jumper is an efficient, inexpensive and uncomplicated fixed flexible functional appliance. It is used to evaluate the efficacy of the Churro Jumper appliance in treatment of skeletal Class II malocclusion with retrognathic mandible. Churro Jumper contri...

  14. A common Shox2-Nkx2-5 antagonistic mechanism primes the pacemaker cell fate in the pulmonary vein myocardium and sinoatrial node.

    Science.gov (United States)

    Ye, Wenduo; Wang, Jun; Song, Yingnan; Yu, Diankun; Sun, Cheng; Liu, Chao; Chen, Fading; Zhang, Yanding; Wang, Fen; Harvey, Richard P; Schrader, Laura; Martin, James F; Chen, YiPing

    2015-07-15

    In humans, atrial fibrillation is often triggered by ectopic pacemaking activity in the myocardium sleeves of the pulmonary vein (PV) and systemic venous return. The genetic programs that abnormally reinforce pacemaker properties at these sites and how this relates to normal sinoatrial node (SAN) development remain uncharacterized. It was noted previously that Nkx2-5, which is expressed in the PV myocardium and reinforces a chamber-like myocardial identity in the PV, is lacking in the SAN. Here we present evidence that in mice Shox2 antagonizes the transcriptional output of Nkx2-5 in the PV myocardium and in a functional Nkx2-5(+) domain within the SAN to determine cell fate. Shox2 deletion in the Nkx2-5(+) domain of the SAN caused sick sinus syndrome, associated with the loss of the pacemaker program. Explanted Shox2(+) cells from the embryonic PV myocardium exhibited pacemaker characteristics including node-like electrophysiological properties and the capability to pace surrounding Shox2(-) cells. Shox2 deletion led to Hcn4 ablation in the developing PV myocardium. Nkx2-5 hypomorphism rescued the requirement for Shox2 for the expression of genes essential for SAN development in Shox2 mutants. Similarly, the pacemaker-like phenotype induced in the PV myocardium in Nkx2-5 hypomorphs reverted back to a working myocardial phenotype when Shox2 was simultaneously deleted. A similar mechanism is also adopted in differentiated embryoid bodies. We found that Shox2 interacts with Nkx2-5 directly, and discovered a substantial genome-wide co-occupancy of Shox2, Nkx2-5 and Tbx5, further supporting a pivotal role for Shox2 in the core myogenic program orchestrating venous pole and pacemaker development.

  15. Hemodynamic instability after pulmonary veins isolation in a patient with dual chamber pacemaker: The phantom injury of the ventricular lead.

    Science.gov (United States)

    Kiuchi, Márcio Galindo; Lobato, Guilherme Miglioli; Chen, Shaojie

    2017-06-01

    The standard treatment of sinus node dysfunction (SND) is the pacemaker implantation, and the ideal methodology for the management of atrial fibrillation (AF) is rhythm control, but this is sometimes very hard to accomplish. For such actions, complete isolation of all pulmonary veins (PVI) is currently widely accepted as the best endpoint. In this case, we report a female patient, 81 years old, with controlled hypertension, without coronary artery disease, bearer of bilateral knee replacement, and dual chamber pacemaker implanted 1.5 years ago owing to sinus node disease, presenting the following symptoms: presyncope episodes associated with sustained irregular palpitation tachycardia. The evaluation of the pacemaker-recorded episodes of atrial fibrillation, the echocardiogram-presented normal systolic function and measurements, as well as the resting myocardial scintigraphy and with drug use did not demonstrate ischemia and/or fibrosis. The patient was in use of valsartan 320 mg daily, amlodipine 10 mg daily, sotalol hydrochloride 120 mg 2 times daily, and dabigatran 110 mg 2 times daily. At the end of the PVI, the patient presented hemodynamic instability, with a decrease in heart rate to 30 bpm and invasive arterial blood pressure to 60/30 mmHg. The pericardial puncture was quickly carried out with the possibility of cardiac tamponade as the first hypothesis, but no pericardial effusion was found. Next, we detected acute capture loss from the ventricular pacemaker lead, unvarying with high voltage and pulse width, even with stable impedance, sense and keeping the same position visualized by fluoroscopy. And there was soon afterwards induction of sustained ventricular tachycardia degenerating to spontaneous ventricular fibrillation. Electrical cardioversion-defibrillation was performed with 200J, and the sinus rhythm was reestablished, but there was a dead short, and the pacemaker generator was burned and disabled. So, we can speculate that

  16. Pacemaker Implants in Children and Adolescents with Chagas Disease in Brazil: 18-Year Incidence.

    Science.gov (United States)

    Mizzaci, Carolina Christianini; Souza, Thiago Gonçalves Schroder E; Targueta, Gabriel Pelegrineti; Tótora, Ana Paula Frederico; Mateos, Juan Carlos Pachón; Mateos, José Carlos Pachon

    2017-06-01

    Chagas disease continues to be a serious public health problem, and accounts for 25-30% of the indications for cardiac stimulation in Brazil. To assess clinical and epidemiological characteristics of patients with Chagas disease, younger than 18 years, who had undergone pacemaker implantation in Brazil between 1994 and 2011, and its temporal trend. This was a cross-sectional analysis of data from the Brazilian Pacemaker Registry database. The following variables were analyzed: year when pacemaker was implanted, location, age, sex, ethnic group, functional class and the main electrocardiographic findings at baseline. In a total of 183,123 implants performed between 1994 and 2011, 214 implants of cardiac stimulation device in Chagas disease patients aged younger than 18 years were identified. Mean age at implantation was 5.6 ± 6.2 years. Second- and third-degree atrioventricular blocks corresponded to 71% of indications for pacemaker implantation. Fifty-six percent of the procedures were performed in the southeast region. Regarding the total number of pacemaker implants per year, there was a remarkable increase in the implants for all causes. However, time series analysis of the implants in Chagas disease patients younger than 18 years revealed a significant reduction in the annual number of implants. There has been an important reduction in the number of pacemaker implantations among children and adolescents with Chagas disease, suggesting a reduction in the vertical transmission of the parasite. A doença de Chagas mantém-se como sério problema de saúde pública e tem sido responsável por aproximadamente 25% a 30% das indicações de estimulação cardíaca no Brasil. Estudar as características clínicas e epidemiológicas dos pacientes menores de 18 anos portadores de doença de Chagas submetidos a implante de marca-passo no território brasileiro entre 1994 e 2011, e sua tendência temporal. Trata-se de um estudo retrospectivo que utilizou informa

  17. Quantification of fiber orientation in the canine atrial pacemaker complex using optical coherence tomography

    Science.gov (United States)

    Ambrosi, Christina M.; Fedorov, Vadim V.; Schuessler, Richard B.; Rollins, Andrew M.

    2012-01-01

    Abstract The atrial pacemaker complex is responsible for the initiation and early propagation of cardiac impulses. Optical coherence tomography (OCT), a nondestructive imaging modality with spatial resolutions of ∼1 to 15 μm, can be used to identify unique fiber orientation patterns in this region of the heart. Functionally characterized canine sinoatrial nodes (SAN) (n=7) were imaged using OCT up to ∼1  mm below the endocardial tissue surface. OCT images were directly compared to their corresponding histological sections. Fiber orientation patterns unique to the crista terminalis (CT), SAN, and surrounding atrial myocardium were identified with dominant average fiber angles of 89±12  deg, 110±16  deg, and 95±35  deg, respectively. Both the CT and surrounding atrial myocardium displayed predominantly unidirectionally based fiber orientation patterns within each specimen, whereas the SAN displayed an increased amount of fiber disarray manifested quantitatively as a significantly greater standard deviation in fiber angle distribution within specimens [33±7  deg versus 23±5  deg, atrium (p=0.02); 18±3  deg, CT (p=0.0003)]. We also identified unique, local patterns of fiber orientation specific to the functionally characterized block zone. We demonstrate the ability of OCT in detecting components of the atrial pacemaker complex which are intimately involved in both normal and abnormal cardiac conduction. PMID:22894470

  18. Forgiveness Flexibility

    Directory of Open Access Journals (Sweden)

    Tuğba Seda Çolak

    2016-01-01

    Full Text Available Forgiveness flexibility is the skill to minimize the negative effect of an event by using cognitive, affective and behavioral skills while taking a stand at the end of an injurious process. A number of studies were conducted to test the flexibility of the structure of forgiveness. The theoretical structure, structural validity and the confirmatory factor analysis supported the theoretical structure of forgiveness flexibility. The criterion validity evaluated in similar manners was found high. Forgiveness flexibility designed as a three dimensional structure and its sub-dimensions was confirmed theoretically as the recognition of forgivenessand the internalization of forgiveness through insight and its practice.

  19. Using Python for scientific computing: Efficient and flexible evaluation of the statistical characteristics of functions with multivariate random inputs

    Science.gov (United States)

    Chudoba, R.; Sadílek, V.; Rypl, R.; Vořechovský, M.

    2013-02-01

    This paper examines the feasibility of high-level Python based utilities for numerically intensive applications via an example of a multidimensional integration for the evaluation of the statistical characteristics of a random variable. We discuss the approaches to the implementation of mathematically formulated incremental expressions using high-level scripting code and low-level compiled code. Due to the dynamic typing of the Python language, components of the algorithm can be easily coded in a generic way as algorithmic templates. Using the Enthought Development Suite they can be effectively assembled into a flexible computational framework that can be configured to execute the code for arbitrary combinations of integration schemes and versions of instantiated code. The paper describes the development cycle using a simple running example involving averaging of a random two-parametric function that includes discontinuity. This example is also used to compare the performance of the available algorithmic and executional features. The implemented package including further examples and the results of performance studies have been made available via the free repository [1] and CPCP library. Program summaryProgram title: spirrid Catalogue identifier: AENL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Special licence provided by the author No. of lines in distributed program, including test data, etc.: 10722 No. of bytes in distributed program, including test data, etc.: 157099 Distribution format: tar.gz Programming language: Python and C. Computer: PC. Operating system: LINUX, UNIX, Windows. Classification: 4.13, 6.2. External routines: NumPy (http://numpy.scipy.org/), SciPy (http://www.scipy.com) Nature of problem: Evaluation of the statistical moments of a function of random variables. Solution method: Direct multidimensional

  20. Conflicting flexibility

    NARCIS (Netherlands)

    De Jong, P.; Schaap, A.

    2011-01-01

    New buildings are designed for first users. For a sustainable approach there are many advantages in designing in flexibility and adjustability in order to enable and facilitate the other sequential users. For the first investor this flexibility is translated into improved exit values due to

  1. Percutaneous Implantation of an Entirely Intracardiac Leadless Pacemaker.

    Science.gov (United States)

    Reddy, Vivek Y; Exner, Derek V; Cantillon, Daniel J; Doshi, Rahul; Bunch, T Jared; Tomassoni, Gery F; Friedman, Paul A; Estes, N A Mark; Ip, John; Niazi, Imran; Plunkitt, Kenneth; Banker, Rajesh; Porterfield, James; Ip, James E; Dukkipati, Srinivas R

    2015-09-17

    Cardiac pacemakers are limited by device-related complications, notably infection and problems related to pacemaker leads. We studied a miniaturized, fully self-contained leadless pacemaker that is nonsurgically implanted in the right ventricle with the use of a catheter. In this multicenter study, we implanted an active-fixation leadless cardiac pacemaker in patients who required permanent single-chamber ventricular pacing. The primary efficacy end point was both an acceptable pacing threshold (≤2.0 V at 0.4 msec) and an acceptable sensing amplitude (R wave ≥5.0 mV, or a value equal to or greater than the value at implantation) through 6 months. The primary safety end point was freedom from device-related serious adverse events through 6 months. In this ongoing study, the prespecified analysis of the primary end points was performed on data from the first 300 patients who completed 6 months of follow-up (primary cohort). The rates of the efficacy end point and safety end point were compared with performance goals (based on historical data) of 85% and 86%, respectively. Additional outcomes were assessed in all 526 patients who were enrolled as of June 2015 (the total cohort). The leadless pacemaker was successfully implanted in 504 of the 526 patients in the total cohort (95.8%). The intention-to-treat primary efficacy end point was met in 270 of the 300 patients in the primary cohort (90.0%; 95% confidence interval [CI], 86.0 to 93.2, P=0.007), and the primary safety end point was met in 280 of the 300 patients (93.3%; 95% CI, 89.9 to 95.9; P<0.001). At 6 months, device-related serious adverse events were observed in 6.7% of the patients; events included device dislodgement with percutaneous retrieval (in 1.7%), cardiac perforation (in 1.3%), and pacing-threshold elevation requiring percutaneous retrieval and device replacement (in 1.3%). The leadless cardiac pacemaker met prespecified pacing and sensing requirements in the large majority of patients. Device

  2. Functional integrity of flexible n-channel metal-oxide-semiconductor field-effect transistors on a reversibly bistable platform

    Science.gov (United States)

    Alfaraj, Nasir; Hussain, Aftab M.; Torres Sevilla, Galo A.; Ghoneim, Mohamed T.; Rojas, Jhonathan P.; Aljedaani, Abdulrahman B.; Hussain, Muhammad M.

    2015-10-01

    Flexibility can bring a new dimension to state-of-the-art electronics, such as rollable displays and integrated circuit systems being transformed into more powerful resources. Flexible electronics are typically hosted on polymeric substrates. Such substrates can be bent and rolled up, but cannot be independently fixed at the rigid perpendicular position necessary to realize rollable display-integrated gadgets and electronics. A reversibly bistable material can assume two stable states in a reversible way: flexibly rolled state and independently unbent state. Such materials are used in cycling and biking safety wristbands and a variety of ankle bracelets for orthopedic healthcare. They are often wrapped around an object with high impulsive force loading. Here, we study the effects of cumulative impulsive force loading on thinned (25 μm) flexible silicon-based n-channel metal-oxide-semiconductor field-effect transistor devices housed on a reversibly bistable flexible platform. We found that the transistors have maintained their high performance level up to an accumulated 180 kN of impact force loading. The gate dielectric layers have maintained their reliability, which is evidenced by the low leakage current densities. Also, we observed low variation in the effective electron mobility values, which manifests that the device channels have maintained their carrier transport properties.

  3. Functional integrity of flexible n-channel metal–oxide–semiconductor field-effect transistors on a reversibly bistable platform

    KAUST Repository

    Alfaraj, Nasir

    2015-10-26

    Flexibility can bring a new dimension to state-of-the-art electronics, such as rollable displays and integrated circuit systems being transformed into more powerful resources. Flexible electronics are typically hosted on polymeric substrates. Such substrates can be bent and rolled up, but cannot be independently fixed at the rigid perpendicular position necessary to realize rollable display-integrated gadgets and electronics. A reversibly bistable material can assume two stable states in a reversible way: flexibly rolled state and independently unbent state. Such materials are used in cycling and biking safety wristbands and a variety of ankle bracelets for orthopedic healthcare. They are often wrapped around an object with high impulsive force loading. Here, we study the effects of cumulative impulsive force loading on thinned (25 μm) flexible silicon-based n-channel metal–oxide–semiconductor field-effect transistor devices housed on a reversibly bistable flexible platform. We found that the transistors have maintained their high performance level up to an accumulated 180 kN of impact force loading. The gate dielectric layers have maintained their reliability, which is evidenced by the low leakage current densities. Also, we observed low variation in the effective electron mobility values, which manifests that the device channels have maintained their carrier transport properties.

  4. Transient apical dyskinesia with a pacemaker: Electrocardiographic features.

    Science.gov (United States)

    Núñez-Gil, Iván J; Feltes, Gisela I; Mejía-Rentería, Hernán D; Biagioni, Corina; De Agustín, J Alberto; Vivas, David; Fernández-Ortiz, Antonio

    2015-04-01

    Transient apical dyskinesia syndromes present features similar to acute coronary syndromes, but with normal coronary arteries and rapid complete resolution of wall motion alterations. We report the case of a 73-year-old woman who was admitted to hospital because of typical chest pain at rest after her brother's death. She had had a pacemaker implanted in 2001. Troponin levels were elevated and apical hypokinesia was shown by ventriculography and echocardiography, with normal coronary arteries. Evolving ECG alterations were observed in spite of the continued pacing rhythm. All these alterations were fully resolved after discharge. This case shows that, even in the presence of a pacemaker, evolving ECG alterations can be observed in Takotsubo syndrome.

  5. Persistently active, pacemaker-like neurons in neocortex

    Directory of Open Access Journals (Sweden)

    Morgane Le Bon-Jego

    2007-10-01

    Full Text Available The neocortex is spontaneously active, however, the origin of this self-generated, patterned activity remains unknown. To detect potential pacemaker cells, we use calcium imaging to directly identify neurons that discharge action potentials in the absence of synaptic transmissionin slices from juvenile mouse visual cortex. We characterize 60 of these neurons electrophysiologically and morphologically, finding that they belong to two classes of cells: one class composed of pyramidal neurons with a thin apical dendritic tree and a second class composed of ascending axon interneurons (Martinotti cells located in layer 5. In both types of neurons, persistent sodium currents are necessary for the generation of the spontaneous activity. Our data demonstrate that subtypes of neocortical neurons have intrinsic mechanisms to generate persistent activity. Like in central pattern generators (CPGs, these neurons may act as pacemakers to initiate or pattern spontaneous activity in the neocortex.

  6. Femoral approach: an exceptional alternative for permanent pacemaker implantation.

    Science.gov (United States)

    Tereno Valente, Bruno; Conceição, José M; Nogueira da Silva, Manuel; M Oliveira, Mário; S Cunha, Pedro; Lousinha, Ana; Galrinho, Ana; C Ferreira, Rui

    2014-05-01

    The classic transvenous implantation of a permanent pacemaker in a pectoral location may be precluded by obstruction of venous access through the superior vena cava or recent infection at the implant site. When these barriers to the procedure are bilateral and there are also contraindications or technical difficulties to performing a thoracotomy for an epicardial approach, the femoral vein, although rarely used, can be a viable alternative. We describe the case of a patient with occlusion of both subclavian veins and a high risk for mini-thoracotomy or videothoracoscopy, who underwent implantation of a permanent single-chamber pacemaker via the right femoral vein. Copyright © 2013 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  7. [Representations, myths, and behaviors among Chagas disease patients with pacemakers].

    Science.gov (United States)

    Magnani, Claudia; Oliveira, Bruna Guimarães; Gontijo, Eliane Dias

    2007-07-01

    This anthropological study aimed to evaluate the incorporation of pacemakers into the lives of individuals with Chagas disease. An ethnographic methodology was used, based on an open interview focusing on the personal perceptions of 15 patients with chronic Chagas cardiopathy who had required pacemaker implants at the Federal University Hospital in Belo Horizonte, Minas Gerais State, Brazil. As part of a broader quality of life analysis, the study investigated the cultural, physical, and psychological resources used by patients to confront, explain, and accept the disease process, including mental representations on the cultural perception of the illness and definition of social relations. The study was intended to contribute to comprehensive patient care by health professionals, including psychosocial aspects. Decoded and integrated orientation in the cultural sphere assumes an important role in order to prevent disinformation from perpetuating the dissemination of popular myths as active elements in patient stigmatization.

  8. Kit- and Fc epsilonRI-induced differential phosphorylation of the transmembrane adaptor molecule NTAL/LAB/LAT2 allows flexibility in its scaffolding function in mast cells

    DEFF Research Database (Denmark)

    Iwaki, Shoko; Spicka, Jiri; Tkaczyk, Christine;

    2008-01-01

    The transmembrane adaptor protein (TRAP), NTAL, is phosphorylated in mast cells following FcvarepsilonRI aggregation whereby it cooperates with LAT to induce degranulation. The Kit ligand, stem cell factor (SCF), enhances antigen-induced degranulation and this also appears to be NTAL......-knock down-human mast cells. The observations reported herein support the conclusion that NTAL may be differentially utilized by specific receptors for relaying alternative signals and this suggests a flexibility in the function of TRAPs not previously appreciated....

  9. Screening Hofmann Compounds as CO 2 Sorbents: Nontraditional Synthetic Route to Over 40 Different Pore-Functionalized and Flexible Pillared Cyanonickelates

    Energy Technology Data Exchange (ETDEWEB)

    Culp, Jeffrey T.; Madden, Catherine; Kauffman, Kristi; Shi, Fan; Matranga, Christopher

    2013-04-15

    A simple reaction scheme based on the heterogeneous intercalation of pillaring ligands (HIPLs) provides a convenient method for systematically tuning pore size, pore functionality, and network flexibility in an extended series of pillared cyanonickelates (PICNICs), commonly referred to as Hofmann compounds. The versatility of the approach is demonstrated through the preparation of over 40 different PICNICs containing pillar ligands ranging from ~4 to ~15 Å in length and modified with a wide range of functional groups, including fluoro, aldehyde, alkylamine, alkyl, aryl, trifluoromethyl, ester, nitro, ether, and nonmetalated 4,4'-bipyrimidine. The HIPL method involves reaction of a suspension of preformed polymeric sheets of powdered anhydrous nickel cyanide with an appropriate pillar ligand in refluxing organic solvent, resulting in the conversion of the planar [Ni{sub 2}(CN){sub 4}]{sub n} networks into polycrystalline three-dimensional porous frameworks containing the organic pillar ligand. Preliminary investigations indicate that the HIPL reaction is also amenable to forming Co(L)Ni(CN){sub 4}, Fe(L)Ni(CN){sub 4}, and Fe(L)Pd(CN){sub 4} networks. The materials show variable adsorption behavior for CO{sub 2} depending on the pillar length and pillar functionalization. Several compounds show structurally flexible behavior during the adsorption and desorption of CO{sub 2}. Interestingly, the newly discovered flexible compounds include two flexible Fe(L)Ni(CN){sub 4} derivatives that are structurally related to previously reported porous spin-crossover compounds. The preparations of 20 pillar ligands based on ring-functionalized 4,4'-dipyridyls, 1,4-bis(4- pyridyl)benzenes, and N-(4-pyridyl)isonicotinamides are also described.

  10. Hardness, function, emotional well-being, satisfaction and the overall sexual experience in men using 100-mg fixed-dose or flexible-dose sildenafil citrate

    Science.gov (United States)

    Ströberg, P; Kaminetsky, J C; Park, N C; Goldfischer, E R; Creanga, D L; Stecher, V J

    2010-01-01

    The prescribing information for sildenafil citrate (VIAGRA, Pfizer, New York, NY, USA) recommends flexible dosing (50 mg initially, adjusted to 100 or 25 mg based on effectiveness and tolerability) in most men with erectile dysfunction (ED). In many men, however, 100 mg may be the most appropriate initial dose because it would reduce the need for titration and could prevent discouragement and treatment abandonment should 50 mg be insufficient. Results of two previously published double-blind, placebo-controlled sildenafil trials of similar design except for a fixed-dose vs flexible-dose regimen were analyzed. Relative to the flexible-dose, approximately one-third more men were satisfied with an initial and fixed dose of 100 mg. In addition, tolerability was similar, and improvements from baseline in outcomes on validated, ED-specific, patient-reported questionnaires were either similar (erectile function and the percentage of completely hard and fully rigid erections) or greater (emotional well-being and the overall sexual experience). The similarity in outcomes is not surprising given that almost 90% of the men in the flexible-dose trial titrated to 100 mg after 2 weeks. These data suggest prescription of an initial dose of 100 mg for men with ED, except in those for whom it is inappropriate. PMID:20596083

  11. A Research on Functions of Flexibility Training in Taekwondo%柔韧素质在跆拳道运动中的作用研究

    Institute of Scientific and Technical Information of China (English)

    孟云鹏

    2015-01-01

    对柔韧素质在跆拳道运动项目中的作用进行研究。结果表明,良好的柔韧素质能够提高运动员的协调性,使运动员较快地掌握腿法技术动作,提高完成动作的质量,在竞技比赛中减少失分现象,提高比赛成绩。%In taekwondo , flexibility is an important physical quality for performance of taekwondo techniques . In view of that head strikes gain more scores in current taekwondo contests and under the influences of the uses of higher level techniques and the rule of points deducted in case of knockdown , flexibility has been seen as an essen-tial factor for enhancing taekwondo performance .By literature study , measurement method , statistics, the functions of taekwondo flexibility training are studied in this paper .As the results indicate , good flexibility can lead to im-proved coordination ability and help the athletes master kick techniques and improve performance of taekwondo movements, to better avoid score deduction in contests and improve game scores .

  12. Effects of Lubiprostone on Pacemaker Activity of Interstitial Cells of Cajal from the Mouse Colon

    OpenAIRE

    Jiao, Han-Yi; Kim, Dong Hyun; Ki, Jung Suk; Ryu, Kwon Ho; Choi, Seok; Jun, Jae Yeoul

    2014-01-01

    Lubiprostone is a chloride (Cl-) channel activator derived from prostaglandin E1 and used for managing constipation. In addition, lubiprostone affects the activity of gastrointestinal smooth muscles. Interstitial cells of Cajal (ICCs) are pacemaker cells that generate slow-wave activity in smooth muscles. We studied the effects of lubiprostone on the pacemaker potentials of colonic ICCs. We used the whole-cell patch-clamp technique to determine the pacemaker activity in cultured colonic ICCs ...

  13. Haemophilus parainfluenzae bacteremia associated with a pacemaker wire localized by gallium scan

    Energy Technology Data Exchange (ETDEWEB)

    Rosenbaum, G.S.; Calubiran, O.; Cunha, B.A. (Winthrop-Univ. Hospital, Mineola, NY (USA))

    1990-05-01

    A young woman with a history of sick sinus syndrome and placement of a permanent pacemaker 6 months before admission had fever and Haemophilus parainfluenzae bacteremia. A gallium scan localized the infection to the site of the pacemaker wire. Echocardiograms were negative for any vegetations. The patient responded to cefotaxime and trimethoprim-sulfamethoxazole therapy. We believe that this is the first case of H. parainfluenzae bacteremia associated with a pacemaker wire and localized by gallium scan.

  14. Flexible and static wrist units in upper limb prosthesis users : functionality scores, user satisfaction and compensatory movements

    NARCIS (Netherlands)

    Deijs, Marieke; Bongers, R. M.; Ringeling-van Leusen, N. D. M.; van der Sluis, C. K.

    2016-01-01

    Background: The current study examines the relevance of prosthetic wrist movement to facilitate activities of daily living or to prevent overuse complaints. Prosthesis hands with wrist flexion/extension capabilities are commercially available, but research on the users' experiences with flexible wri

  15. Flexible and static wrist units in upper limb prosthesis users : functionality scores, user satisfaction and compensatory movements

    NARCIS (Netherlands)

    Deijs, M; Bongers, R M; Ringeling-van Leusen, N D M; van der Sluis, C K

    2016-01-01

    BACKGROUND: The current study examines the relevance of prosthetic wrist movement to facilitate activities of daily living or to prevent overuse complaints. Prosthesis hands with wrist flexion/extension capabilities are commercially available, but research on the users' experiences with flexible wri

  16. Is executive function specifically impaired in children with neurofibromatosis type 1? A neuropsychological investigation of cognitive flexibility.

    Science.gov (United States)

    Roy, Arnaud; Barbarot, Sébastien; Roulin, Jean-Luc; Charbonnier, Valérie; Fasotti, Luciano; Stalder, Jean-François; Le Gall, Didier

    2014-01-01

    Our study investigated spontaneous versus reactive cognitive flexibility in children with neurofibromatosis type 1 (NF1) and their comorbidity with attention-deficit hyperactivity disorder (ADHD). Thirty children with NF1 aged 7 to 12 years old were compared to 60 healthy controls matched by age, gender, and parental education. On the basis of Eslinger and Grattan's definition ( 1993 ), spontaneous shifting was assessed using fluency tests, whereas reactive flexibility was measured by a child adaptation of the Modified Card-Sorting Test and the Brixton Test. IQ and basic skills were taken into account as confounding variables that might influence executive measures. NF1 children performed below the level of healthy children on both reactive flexibility tasks, even when intelligence and basic skills were partialled out, but ADHD symptomatology was not found to adversely affect the performance of patients. Our findings support the hypothesis of a specific executive impairment in NF1, uncovering a dissociation between (impaired) reactive flexibility and (preserved) spontaneous shifting, with no impact of ADHD on executive performance.

  17. RNA versatility governs tRNA function: Why tRNA flexibility is essential beyond the translation cycle.

    Science.gov (United States)

    Kuhn, Claus-D

    2016-05-01

    tRNAs undergo multiple conformational changes during the translation cycle that are required for tRNA translocation and proper communication between the ribosome and translation factors. Recent structural data on how destabilized tRNAs utilize the CCA-adding enzyme to proofread themselves put a spotlight on tRNA flexibility beyond the translation cycle. In analogy to tRNA surveillance, this review finds that other processes also exploit versatile tRNA folding to achieve, amongst others, specific aminoacylation, translational regulation by riboswitches or a block of bacterial translation. tRNA flexibility is thereby not restricted to the hinges utilized during translation. In contrast, the flexibility of tRNA is distributed all over its L-shape and is actively exploited by the tRNA-interacting partners to discriminate one tRNA from another. Since the majority of tRNA modifications also modulate tRNA flexibility it seems that cells devote enormous resources to tightly sense and regulate tRNA structure. This is likely required for error-free protein synthesis.

  18. Different Executive Functions Support Different Kinds of Cognitive Flexibility: Evidence from 2-, 3-, and 4-Year-Olds

    Science.gov (United States)

    Blakey, Emma; Visser, Ingmar; Carroll, Daniel J.

    2016-01-01

    Improvements in cognitive flexibility during the preschool years have been linked to developments in both working memory and inhibitory control, though the precise contribution of each remains unclear. In the current study, one hundred and twenty 2-, 3-, and 4-year-olds completed two rule-switching tasks. In one version, children switched rules in…

  19. A Systematic Review of Economic Evaluations of Pacemaker Telemonitoring Systems.

    Science.gov (United States)

    López-Villegas, Antonio; Catalán-Matamoros, Daniel; Martín-Saborido, Carlos; Villegas-Tripiana, Irene; Robles-Musso, Emilio

    2016-02-01

    Over the last decade, telemedicine applied to pacemaker monitoring has undergone extraordinary growth. It is not known if telemonitoring is more or less efficient than conventional monitoring. The aim of this study was to carry out a systematic review analyzing the available evidence on resource use and health outcomes in both follow-up modalities. We searched 11 databases and included studies published up until November 2014. The inclusion criteria were: a) experimental or observational design; b) studies based on complete economic evaluations; c) patients with pacemakers, and d) telemonitoring compared with conventional hospital monitoring. Seven studies met the inclusion criteria, providing information on 2852 patients, with a mean age of 81 years. The main indication for device implantation was atrioventricular block. With telemonitoring, cardiovascular events were detected and treated 2 months earlier than with conventional monitoring, thus reducing length of hospital stay by 34% and reducing routine and emergency hospital visits as well. There were no significant intergroup differences in perceived quality of life or number of adverse events. The cost of telemonitoring was 60% lower than that of conventional hospital monitoring. Compared with conventional monitoring, cardiovascular events were detected earlier and the number or hospitalizations and hospital visits was reduced with pacemaker telemonitoring. In addition, the costs associated with follow-up were lower with telemonitoring. Copyright © 2015 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  20. Isolating neural correlates of the pacemaker for food anticipation.

    Directory of Open Access Journals (Sweden)

    Ian David Blum

    Full Text Available Mice fed a single daily meal at intervals within the circadian range exhibit food anticipatory activity. Previous investigations strongly suggest that this behaviour is regulated by a circadian pacemaker entrained to the timing of fasting/refeeding. The neural correlate(s of this pacemaker, the food entrainable oscillator (FEO, whether found in a neural network or a single locus, remain unknown. This study used a canonical property of circadian pacemakers, the ability to continue oscillating after removal of the entraining stimulus, to isolate activation within the neural correlates of food entrainable oscillator from all other mechanisms driving food anticipatory activity. It was hypothesized that continued anticipatory activation of central nuclei, after restricted feeding and a return to ad libitum feeding, would elucidate a neural representation of the signaling circuits responsible for the timekeeping component of the food entrainable oscillator. Animals were entrained to a temporally constrained meal then placed back on ad libitum feeding for several days until food anticipatory activity was abolished. Activation of nuclei throughout the brain was quantified using stereological analysis of c-FOS expressing cells and compared against both ad libitum fed and food entrained controls. Several hypothalamic and brainstem nuclei remained activated at the previous time of food anticipation, implicating them in the timekeeping mechanism necessary to track previous meal presentation. This study also provides a proof of concept for an experimental paradigm useful to further investigate the anatomical and molecular substrates of the FEO.

  1. Reuse of pacemakers, defibrillators and cardiac resynchronisation devices

    Science.gov (United States)

    Sakthivel, R; Satheesh, Santhosh; Ananthakrishna Pillai, Ajith; Sagnol, Pascal; Jouven, Xavier; Dodinot, Bernard; Balachander, Jayaraman

    2017-01-01

    Objective Access to pacemakers remains poor among many patients in low/middle-income countries. Reuse of explanted pacemakers is a possible solution, but is still not widespread because of concerns regarding outcomes, especially infection. Our objective was to study early outcomes with implants using reused devices and compare them with those with implants using new devices. Methods We studied all patients who underwent implantation of a new or reused pacemaker, cardiac resynchronisation therapy (CRT) device or implantable cardioverter defibrillator (ICD) in the last 5 years at a single institution. We analysed outcomes related to infection, device malfunction and device-related death within 6 months after initial implantation. Results During the study period, 887 patients underwent device implant, including 127 CRT devices or ICDs. Of these, 260 devices (29.3%) were reused and the others were new. At 6 months, there were three device-related infections in implants using a new device. There were no infections among patients receiving a reused device. There were no device malfunctions or device-related deaths in either group. Conclusions We found no difference in rate of infection or device malfunction among patients getting a reused device as compared with those with a new device. This study reinforces the safety of reusing devices for implant including CRT and ICDs. PMID:28176981

  2. Percutaneous Extraction of Transvenous Permanent Pacemaker/Defibrillator Leads

    Directory of Open Access Journals (Sweden)

    Stylianos Paraskevaidis

    2014-01-01

    Full Text Available Background. Widespread use of cardiovascular implantable electronic devices has inevitably increased the need for lead revision/replacement. We report our experience in percutaneous extraction of transvenous permanent pacemaker/defibrillator leads. Methods. Thirty-six patients admitted to our centre from September 2005 through October 2012 for percutaneous lead extraction were included. Lead removal was attempted using Spectranetics traction-type system (Spectranetics Corp., Colorado, CO, USA and VascoExtor countertraction-type system (Vascomed GmbH, Weil am Rhein, Germany. Results. Lead extraction was attempted in 59 leads from 36 patients (27 men, mean ± SD age 61±5 years, with permanent pacemaker (n=25, defibrillator (n=8, or cardiac resynchronisation therapy (n=3 with a mean ± SD implant duration of 50±23 months. The indications for lead removal included pocket infection (n=23, endocarditis (n=2, and ventricular (n=10 and atrial lead dysfunction (n=1. Traction device was used for 33 leads and countertraction device for 26 leads. Mean ± SD fluoroscopy time was 4±2 minutes/lead for leads implanted 48 months (n=21, P=0.03. Complete procedural success rate was 91.7% and clinical procedural success rate was 100%, while lead procedural success rate was 95%. Conclusions. In conclusion, percutaneous extraction of transvenous permanent pacemaker/defibrillator leads using dedicated removal tools is both feasible and safe.

  3. Permanent and temporary pacemaker implantation after orthotopic heart transplantation

    Directory of Open Access Journals (Sweden)

    Bacal Fernando

    2000-01-01

    Full Text Available PURPOSE:To determine the indication for and incidence and evolution of temporary and permanent pacemaker implantation in cardiac transplant recipients. METHODS: A retrospective review of 114 patients who underwent orthotopic heart transplantation InCor (Heart Institute USP BR between March 1985 and May 1993. We studied the incidence of and indication for temporary pacing, the relationship between pacing and rejection, the need for pemanent pacing and the clinical follow-up. RESULTS: Fourteen of 114 (12%heart transplant recipients required temporary pacing and 4 of 114 (3.5% patients required permanent pacing. The indication for temporary pacing was sinus node dysfunction in 11 patients (78.5% and atrioventricular (AV block in 3 patients (21.4%. The indication for permanent pacemaker implantation was sinus node dysfunction in 3 patients (75% and atrioventricular (AV block in 1 patient (25%. We observed rejection in 3 patients (21.4% who required temporary pacing and in 2 patients (50% who required permanent pacing. The previous use of amiodarone was observed in 10 patients (71.4% with temporary pacing. Seven of the 14 patients (50% died during follow-up. CONCLUSION: Sinus node dysfunction was the principal indication for temporary and permanent pacemaker implantation in cardiac transplant recipients. The need for pacing was related to worse prognosis after cardiac transplantation.

  4. Nursing procedure in the temporary transvenous pacemaker implantation

    Directory of Open Access Journals (Sweden)

    Mª Teresa Redecillas Peiró

    2013-05-01

    Full Text Available The temporary transvenous pacemaker (MPTT implantation is a technique that consists in stimulating artificially the heart when the natural pacemaker is unable to maintain the rhythm and the appropiate frequency. This type of electric stimulation is carried out by means of an electrocateter that was implanted in the endocardium through a central vein connected to an external generator, requiring equipment and personal with specific abilities. It is commonly carried out in the intensive care units when a continuous temporary stimulation is suitable and in most cases it is carried out in situations of extreme medical urgency in critical and unstable patients. The nursing professionals play an important role in the whole procedure, becoming essential that they possess knowledge not only about technique and handling of the device but also on the performance in all its phases. This research work intends to be a practical reference that gathers those essential aspects for the development of this assistance practice including, in a detailed way, the nursing performance in the preparation, the implantation and the pursuit of the patients who a temporary transvenous pacemaker was placed in.

  5. Flexible Sigmoidoscopy

    Science.gov (United States)

    ... Task Force (USPSTF). Most doctors recommend colonoscopy to screen for colon cancer because colonoscopy shows the entire colon and can remove colon polyps. However, preparing for and performing a flexible sigmoidoscopy may take less time and you may ...

  6. Intra-SA-nodal pacemaker shifts induced by autonomic nerve stimulation in the dog.

    Science.gov (United States)

    Goldberg, J M

    1975-10-01

    Pacemaker shifts in the canine heart were inferred during stimulation of thoracic cardiac nerves and following norepinephrine from changes in the initial site of activation of bipolar electrodes sutured over the rostral, middle, and caudal regions of the sinus node, over the internodal pathways, and His bundle. During control periods, pacemaker activity was localized within the sinoatrial (SA) node 87% of the time, with the middle electrode most frequently showing initial activation. Stimulation of the right-sympathetic nerves enhanced sinus node pacemaker dominance, shifting it rostrally within the node. Right-vagal stimulation shifted the pacemaker caudally within the SA node, to nonnodal sites, and to the lower atrioventricular node and His bundle. Left-sympathetic stimulation shifted the pacemaker caudally within the sinus node and enhanced pacemaker activity in the vicinity of the internodal pathway electrodes and His bundle. Dispersion of pacemaker activity was particularly apparent during stimulation of the ventrolateral cervical cardiac nerve. Stimulation of the left-vagal nerves produced effects similar to those of the left-sympathetic nerves. Norepinephrine enhanced pacemaker activity particularly in the rostral region of the sinus node. Slight shifts in pacemaker activity within the sinus node produced changes in pattern of atrial excitation.

  7. Permanent pacemaker lead induced severe tricuspid regurgitation in patient undergoing multiple valve surgery.

    Science.gov (United States)

    Lee, Jung Hee; Kim, Tae Ho; Kim, Wook Sung

    2015-04-01

    Severe and permanent tricuspid regurgitation induced by pacemaker leads is rarely reported in the literature. The mechanism of pacemaker-induced tricuspid regurgitation has been identified, but its management has not been well established. Furthermore, debate still exists regarding the proper surgical approach. We present the case of a patient with severe tricuspid regurgitation induced by a pacemaker lead, accompanied by triple valve disease. The patient underwent double valve replacement and tricuspid valve repair without removal of the pre-existing pacemaker lead. The operation was successful and the surgical procedure is discussed in detail.

  8. Modulation of Pacemaker Potentials by Pyungwi-San in Interstitial Cells of Cajal from Murine Small Intestine - Pyungwi-San and Interstitial Cells of Cajal -

    Directory of Open Access Journals (Sweden)

    Kim Jung Nam

    2013-03-01

    Full Text Available Objective: Pyungwi-san (PWS plays a role in a number of physiologic and pharmacologic functions in many organs. Interstitial cells of Cajal (ICCs are pacemaker cells that generate slow waves in the gastrointestinal (GI tract. We aimed to investigate the beneficial effects of PWS in mouse small-intestinal ICCs. Methods: Enzymatic digestion was used to dissociate ICCs from the small intestine of a mouse. The wholecell patch-clamp configuration was used to record membrane potentials from the cultured ICCs. Results: ICCs generated pacemaker potentials in the GI tract. PWS produced membrane depolarization in the current clamp mode. Pretreatment with a Ca2+-free solution and a thapsigargin, a Ca2+-ATPase, inhibitor in the endoplasmic reticulum, eliminated the generation of pacemaker potentials. However, only when the thapsigargin was applied in a bath solution, the membrane depolarization was not produced by PWS. Furthermore, the membrane depolarizations due to PWS were inhibited not by U-73122, an active phospholipase C inhibitor, but by chelerythrine and calphostin C, protein kinase C inhibitors. Conclusions: These results suggest that PWS might affect GI motility by modulating the pacemaker activity in the ICCs.

  9. Ultrasonic-electrodeposition of PtPd alloy nanoparticles on ionic liquid-functionalized graphene paper: towards a flexible and versatile nanohybrid electrode

    Science.gov (United States)

    Sun, Yimin; Zheng, Huaming; Wang, Chenxu; Yang, Mengmeng; Zhou, Aijun; Duan, Hongwei

    2016-01-01

    Here we fabricate a new type of flexible and versatile nanohybrid paper electrode by ultrasonic-electrodeposition of PtPd alloy nanoparticles on freestanding ionic liquid (IL)-functionalized graphene paper, and explore its multifunctional applications in electrochemical catalysis and sensing systems. The graphene-based paper materials demonstrate intrinsic flexibility, exceptional mechanical strength and high electrical conductivity, and therefore can serve as an ideal freestanding flexible electrode for electrochemical devices. Furthermore, the functionalization of graphene with IL (i.e., 1-butyl-3-methylimidazolium tetrafluoroborate) not only increases the electroactive surface area of a graphene-based nanohybrid paper electrode, but also improves the adhesion and dispersion of metal nanoparticles on the paper surface. These unique attributes, combined with the merits of an ultrasonic-electrodeposition method, lead to the formation of PtPd alloy nanoparticles on IL-graphene paper with high loading, uniform distribution, controlled morphology and favourable size. Consequently, the resultant nanohybrid paper electrode exhibits remarkable catalytic activity as well as excellent cycle stability and improved anti-poisoning ability towards electrooxidation of fuel molecules such as methanol and ethanol. Furthermore, for nonenzymatic electrochemical sensing of some specific biomarkers such as glucose and reactive oxygen species, the nanohybrid paper electrode shows high selectivity, sensitivity and biocompatibility in these bio-catalytic processes, and can be used for real-time tracking hydrogen peroxide secretion by living human cells. All these features demonstrate its promising application as a versatile nanohybrid electrode material in flexible and lightweight electrochemical energy conversion and biosensing systems such as bendable on-chip power sources, wearable/implantable detectors and in vivo micro-biosensors.Here we fabricate a new type of flexible and

  10. A flexible loop as a functional element in the catalytic mechanism of nucleoside hydrolase from Trypanosoma vivax.

    Science.gov (United States)

    Vandemeulebroucke, An; De Vos, Stefan; Van Holsbeke, Els; Steyaert, Jan; Versées, Wim

    2008-08-08

    The nucleoside hydrolase of Trypanosoma vivax hydrolyzes the N-glycosidic bond of purine nucleosides. Structural and kinetic studies on this enzyme have suggested a catalytic role for a flexible loop in the vicinity of the active sites. Here we present the analysis of the role of this flexible loop via the combination of a proline scan of the loop, loop deletion mutagenesis, steady state and pre-steady state analysis, and x-ray crystallography. Our analysis reveals that this loop has an important role in leaving group activation and product release. The catalytic role involves the entire loop and could only be perturbed by deletion of the entire loop and not by single site mutagenesis. We present evidence that the loop closes over the active site during catalysis, thereby ordering a water channel that is involved in leaving group activation. Once chemistry has taken place, the loop dynamics determine the rate of product release.

  11. A flexible multidomain structure drives the function of the urokinase-type plasminogen activator receptor (uPAR)

    DEFF Research Database (Denmark)

    Mertens, Haydyn D.T.; Kjærgaard, Magnus; Mysling, Simon

    2012-01-01

    -deuterium exchange, and surface plasmon resonance to develop a structural model describing the allosteric regulation of uPAR. We show that the flexibility of its N-terminal domain provides the key for understanding this allosteric mechanism. Importantly, our model has direct implications for understanding uPAR-assisted...... cell adhesion and migration as well as for translational research including targeted intervention therapy and non-invasive tumor imaging in vivo....

  12. Flexible and static wrist units in upper limb prosthesis users: functionality scores, user satisfaction and compensatory movements

    OpenAIRE

    Deijs, Marieke; Bongers, R.M.; Ringeling-van Leusen, N. D. M.; van der Sluis, C. K.

    2016-01-01

    Background The current study examines the relevance of prosthetic wrist movement to facilitate activities of daily living or to prevent overuse complaints. Prosthesis hands with wrist flexion/extension capabilities are commercially available, but research on the users’ experiences with flexible wrists is limited. Methods In this study, eight transradial amputees using a myoelectric prosthesis tested two prosthesis wrists with flexion/extension capabilities, the Flex-wrist (Otto Bock) and Mult...

  13. An adaptive method with weight matrix as a function of the state to design the rotatory flexible system control law

    Science.gov (United States)

    Souza, Luiz C. G.; Bigot, P.

    2016-10-01

    One of the most well-known techniques of optimal control is the theory of Linear Quadratic Regulator (LQR). This method was originally applied only to linear systems but has been generalized for non-linear systems: the State Dependent Riccati Equation (SDRE) technique. One of the advantages of SDRE is that the weight matrix selection is the same as in LQR. The difference is that weights are not necessarily constant: they can be state dependent. Then, it gives an additional flexibility to design the control law. Many are applications of SDRE for simulation or real time control but generally SDRE weights are chosen constant so no advantage of this flexibility is taken. This work serves to show through simulation that state dependent weights matrix can improve SDRE control performance. The system is a non-linear flexible rotatory beam. In a brief first part SDRE theory will be explained and the non-linear model detailed. Then, influence of SDRE weight matrix associated with the state Q will be analyzed to get some insight in order to assume a state dependent law. Finally, these laws are tested and compared to constant weight matrix Q. Based on simulation results; one concludes showing the benefits of using an adaptive weight Q rather than a constant one.

  14. Connectivity of Pacemaker Neurons in the Neonatal Rat Superficial Dorsal Horn

    Science.gov (United States)

    Ford, Neil C.; Arbabi, Shahriar; Baccei, Mark L.

    2014-01-01

    Pacemaker neurons with an intrinsic ability to generate rhythmic burst-firing have been characterized in lamina I of the neonatal spinal cord, where they are innervated by high-threshold sensory afferents. However, little is known about the output of these pacemakers, as the neuronal populations which are targeted by pacemaker axons have yet to be identified. The present study combines patch clamp recordings in the intact neonatal rat spinal cord with tract-tracing to demonstrate that lamina I pacemaker neurons contact multiple spinal motor pathways during early life. Retrograde labeling of premotor interneurons with the trans-synaptic virus PRV-152 revealed the presence of burst-firing in PRV-infected lamina I neurons, thereby confirming that pacemakers are synaptically coupled to motor networks in the spinal ventral horn. Notably, two classes of pacemakers could be distinguished in lamina I based on cell size and the pattern of their axonal projections. While small pacemaker neurons possessed ramified axons which contacted ipsilateral motor circuits, large pacemaker neurons had unbranched axons which crossed the midline and ascended rostrally in the contralateral white matter. Recordings from identified spino-parabrachial and spino-PAG neurons indicated the presence of pacemaker activity within neonatal lamina I projection neurons. Overall, these results show that lamina I pacemakers are positioned to regulate both the level of activity in developing motor circuits as well as the ascending flow of nociceptive information to the brain, thus highlighting a potential role for pacemaker activity in the maturation of pain and sensorimotor networks in the CNS. PMID:25380417

  15. Utility and safety of temporary pacing using active fixation leads and externalized re-usable permanent pacemakers after lead extraction

    National Research Council Canada - National Science Library

    Kawata, Hiro; Pretorius, Victor; Phan, Huy; Mulpuru, Siva; Gadiyaram, Varuna; Patel, Jigar; Steltzner, Dawna; Krummen, David; Feld, Gregory; Birgersdotter-Green, Ulrika

    2013-01-01

    .... The use of an externalized permanent active-fixation pacemaker lead connected to a permanent pacemaker generator for temporary pacing may be beneficial because of improved lead stability, and greater...

  16. Piping Flexibility

    Science.gov (United States)

    1978-01-01

    A NASA computer program aids Hudson Engineering Corporation, Houston, Texas, in the design and construction of huge petrochemical processing plants like the one shown, which is located at Ju'aymah, Saudi Arabia. The pipes handling the flow of chemicals are subject to a variety of stresses, such as weight and variations in pressure and temperature. Hudson Engineering uses a COSMIC piping flexibility analysis computer program to analyze stresses and unsure the necessary strength and flexibility of the pipes. This program helps the company realize substantial savings in reduced engineering time.

  17. Flexible, Transparent, Thickness-Controllable SWCNT/PEDOT:PSS Hybrid Films Based on Coffee-Ring Lithography for Functional Noncontact Sensing Device

    KAUST Repository

    Tai, Yanlong

    2015-12-08

    Flexible transparent conductive films (FTCFs) as the essential components of the next generation of functional circuits and devices are presently attracting more attention. Here, a new strategy has been demonstrated to fabricate thickness-controllable FTCFs through coffee ring lithography (CRL) of single-wall carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT:PSS) hybrid ink. The influence of ink concentration and volume on the thickness and size of hybrid film has been investigated systematically. Results show that the final FTCFs present a high performance, including a homogeneous thickness of 60-65 nm, a sheet resistance of 1.8 kohm/sq, a visible/infrared-range transmittance (79%, PET = 90%), and a dynamic mechanical property (>1000 cycle, much better than ITO film), respectively, when SWCNT concentration is 0.2 mg/mL, ink volume is 0.4 μL, drying at room temperature. Moreover, the benefits of these kinds of FTCFs have been verified through a full transparent, flexible noncontact sensing panel (3 × 4 sensing pixels) and a flexible battery-free wireless sensor based on a humidity sensing mechanism, showing excellent human/machine interaction with high sensitivity, good stability, and fast response/recovery ability. © 2015 American Chemical Society.

  18. T-box transcription factor TBX3 reprogrammes mature cardiac myocytes into pacemaker-like cells.

    NARCIS (Netherlands)

    Bakker, M.L.; Boink, G.J.; Boukens, B.J.; Verkerk, A.O.; Boogaard, M.W. van den; Haan, A.D. den; Hoogaars, W.M.; Buermans, H.P.; Bakker, J.M. de; Seppen, J.; Tan, H.L.; Moorman, A.F.; Hoen, P.A.C. 't; Christoffels, V.M.

    2012-01-01

    AIM: Treatment of disorders of the sinus node or the atrioventricular node requires insights into the molecular mechanisms of development and homoeostasis of these pacemaker tissues. In the developing heart, transcription factor TBX3 is required for pacemaker and conduction system development. Here,

  19. Compatibility of Radiofrequency Surgical Sponge Detection Technology with Cardiac Implantable Electronic Devices and Temporary Pacemakers.

    Science.gov (United States)

    Salcedo, Jonathan D; Pretorius, Victor G; Hsu, Jonathan C; Lalani, Gautam G; Schricker, Amir A; Hebsur, Shrinivas M; McGARRY, Thomas J; Hunter, Jessica A; Lewis, Kathryn E; Krummen, David E; Feld, Gregory K; Birgersdotter-Green, Ulrika

    2016-11-01

    Radiofrequency (RF) technology has improved detection of retained surgical sponges with a reported 100% sensitivity and specificity. However, the potential for interactions of the RF signals emitted by the detection system with cardiac implantable electronic devices (CIEDs) or temporary pacemakers may limit its use in those patients with these devices. This study investigated whether RF detection technology causes interference or clinically significant changes in the programmed settings of implanted pacemakers and defibrillators or temporary epicardial pacemakers. Fifty patients who were scheduled either for CIED removal or placement of a temporary epicardial pacemaker (at the time of open heart surgery) were recruited for this study. Device settings and measurements from separate interrogations before and after scanning with the RF detection system were compared. For the temporary pacemakers, we observed for any changes in hemodynamics or signs of pacing interference. Twenty (40%) pacemakers, 20 (40%) implantable cardioverter defibrillators, and 10 (20%) temporary pacemakers were analyzed in this study. During scanning, no signal interference was detected in any permanent device, and there were no significant changes in programmed settings after scanning with the RF detection system. However, pacing inhibition was detected with temporary pacing systems when programmed to a synchronous mode (DDD). RF detection technology can be safely used to scan for retained surgical sponges in patients with permanent CIEDs and temporary pacemakers set to asynchronous mode. © 2016 Wiley Periodicals, Inc.

  20. A forced desynchrony study of circadian pacemaker characteristics in seasonal affective disorder

    NARCIS (Netherlands)

    Koorengevel, Kathelijne M.; Beersma, Domien G.M.; den Boer, Johan; Hoofdakker, Rutger H. van den

    2002-01-01

    The circadian pacemaker is an endogenous clock that regulates oscillations in most physiological and psychological processes with a near 24-h period. In many species, this pacemaker triggers seasonal changes in behavior. The seasonality of symptoms and the efficacy of light therapy suggest

  1. A forced desynchrony study of circadian pacemaker characteristics in seasonal affective disorder

    NARCIS (Netherlands)

    Koorengevel, Kathelijne M.; Beersma, Domien G.M.; den Boer, Johan; Hoofdakker, Rutger H. van den

    2002-01-01

    The circadian pacemaker is an endogenous clock that regulates oscillations in most physiological and psychological processes with a near 24-h period. In many species, this pacemaker triggers seasonal changes in behavior. The seasonality of symptoms and the efficacy of light therapy suggest involveme

  2. Holter recordings with continuous marker annotations: a new tool in pacemaker diagnostics.

    Science.gov (United States)

    Nowak, B; Middeldorf, T; Housworth, C M; Brüls, A; Liebrich, A; Rosocha, S; Voigtländer, T; Himmrich, E; Meyer, J

    1996-11-01

    Pacemakers provide marker annotations to facilitate the interpretation of pacemaker electrocardiograms (ECGs) and can be used in cases of suspected pacemaker malfunction or to understand pacemaker behavior. Due to the need for a programmer, only short-term evaluations are possible. We evaluated a prototype Telemetry Data Logger (TDL) designed to continuously transfer markers from the pacemaker to a conventional Holter recorder. A miniaturized telemetry receiving coil was attached to patient's skin above the pacemaker, which was programmed to transmit markers continuously. The TDL, which receives and converts markers into eight positive and eight negative deflections, ranging from -2.5 to +2.5 mV in amplitude, was connected to one channel of a conventional Holter recorder (Tracker 2). We performed 20 Holters in 13 patients who had implanted VDDR or DDDR devices from the same manufacturer and evaluated three versions of software. Marker transmission was possible in all patients, producing Holter ECGs with complete marker annotations. Artifacts occurred Holter recording, facilitating the interpretation of pacemaker ECGs and the diagnosis of inappropriate pacemaker programming even when not discernible from the surface ECG alone.

  3. PreBötzinger complex and pacemaker neurons: hypothesized site and kernel for respiratory rhythm generation

    DEFF Research Database (Denmark)

    Rekling, J C; Feldman, J L

    1998-01-01

    Identification of the sites and mechanisms underlying the generation of respiratory rhythm is of longstanding interest to physiologists and neurobiologists. Recently, with the development of novel experimental preparations, especially in vitro en bloc and slice preparations of rodent brainstem, p...... activity of pacemaker or group-pacemaker neurons....

  4. Low pacemaker incidence with continuous-sutured valves: a retrospective analysis.

    Science.gov (United States)

    Niclauss, Lars; Delay, Dominique; Pfister, Raymond; Colombier, Sebastien; Kirsch, Matthias; Prêtre, René

    2017-06-01

    Background Permanent pacemaker implantation after surgical aortic valve replacement depends on patient selection and risk factors for conduction disorders. We aimed to identify risk criteria and obtain a selected group comparable to patients assigned to transcatheter aortic valve implantation. Methods Isolated sutured aortic valve replacements in 994 patients treated from 2007 to 2015 were reviewed. Demographics, hospital stay, preexisting conduction disorders, surgical technique, and etiology in patients with and without permanent pacemaker implantation were compared. Reported outcomes after transcatheter aortic valve implantation were compared with those of a subgroup including only degenerative valve disease and first redo. Results The incidence of permanent pacemaker implantation was 2.9%. Longer hospital stay ( p = 0.01), preexisting rhythm disorders ( p pacemaker implantation. Although prostheses were sutured with continuous monofilament in the majority of cases (86%), interrupted pledgetted sutures were used more often in the pacemaker group ( p = 0.002). In the subgroup analysis, the incidence of permanent pacemaker implantation was 2%; preexisting rhythm disorders and the suture technique were still major risk factors. Conclusion Permanent pacemaker implantation depends on etiology, preexisting rhythm disorders, and suture technique, and the 2% incidence compares favorably with the reported 5- to 10-fold higher incidence after transcatheter aortic valve implantation. Cost analysis should take this into account. Often dismissed as minor complication, permanent pacemaker implantation increases the risks of endocarditis, impaired myocardial recovery, and higher mortality if associated with prosthesis regurgitation.

  5. Noise-induced effects on multicellular biopacemaker spontaneous activity: Differences between weak and strong pacemaker cells

    Science.gov (United States)

    Aghighi, Alireza; Comtois, Philippe

    2017-09-01

    Self-organization of spontaneous activity of a network of active elements is important to the general theory of reaction-diffusion systems as well as for pacemaking activity to initiate beating of the heart. Monolayer cultures of neonatal rat ventricular myocytes, consisting of resting and pacemaker cells, exhibit spontaneous activation of their electrical activity. Similarly, one proposed approach to the development of biopacemakers as an alternative to electronic pacemakers for cardiac therapy is based on heterogeneous cardiac cells with resting and spontaneously beating phenotypes. However, the combined effect of pacemaker characteristics, density, and spatial distribution of the pacemaker cells on spontaneous activity is unknown. Using a simple stochastic pattern formation algorithm, we previously showed a clear nonlinear dependency of spontaneous activity (occurrence and amplitude of spontaneous period) on the spatial patterns of pacemaker cells. In this study, we show that this behavior is dependent on the pacemaker cell characteristics, with weaker pacemaker cells requiring higher density and larger clusters to sustain multicellular activity. These multicellular structures also demonstrated an increased sensitivity to voltage noise that favored spontaneous activity at lower density while increasing temporal variation in the period of activity. This information will help researchers overcome the current limitations of biopacemakers.

  6. Twiddler-syndrom er en årsag til pacemaker elektrode displacering

    DEFF Research Database (Denmark)

    Grønbech, Keea Treu; Hansen, Michael Gilså

    2013-01-01

    Twiddler's syndrome is a rare cause of pacemaker electrode displacement. The displacement is caused by the patient's manipulation with the pacemaker, so the electrode is retracted. We describe a case of a 79-year-old overweight woman with a known psychiatric anamnesis, who was admitted twice...

  7. A proposal for a standard communication protocol for pacemaker/ICD programmers

    NARCIS (Netherlands)

    Dijk, WA; Hooijschuur, CAM; van der Velde, W; Dassen, WRM

    2005-01-01

    The information generated by pacemakers and ICD's to support the cardiologist and technician for installing the optimal settings for the patient is increasing rapidly. In this paper a proposal is described for electronic data exchange between the pacemaker/ICD programmers and electronic information

  8. Sandwich-structured nanohybrid paper based on controllable growth of nanostructured MnO2 on ionic liquid functionalized graphene paper as a flexible supercapacitor electrode

    Science.gov (United States)

    Sun, Yimin; Fang, Zheng; Wang, Chenxu; Ariyawansha, K. R. Rakhitha Malinga; Zhou, Aijun; Duan, Hongwei

    2015-04-01

    A sandwich-structured flexible supercapacitor electrode has been developed based on MnO2 nanonest (MNN) modified ionic liquid (IL) functionalized graphene paper (GP), which is fabricated by functionalizing graphene nanosheets with an amine-terminated IL (i.e., 1-(3-aminopropyl)-3-methylimidazolium bromide) to form freestanding IL functionalized GP (IL-GP), and then modifying IL-GP with a unique MNN structure via controllable template-free ultrasonic electrodeposition. The as-obtained MNN modified IL-GP (MNN/IL-GP) inherits the excellent pseudocapacity of the metal oxide, the high conductivity and electric double layer charging/discharging of IL-graphene composites, and therefore shows an enhanced supercapacitor performance. The maximum specific capacitance of 411 F g-1 can be achieved by chronopotentiometry at a current density of 1 A g-1. Meanwhile, the MNN/IL-GP electrode exhibits excellent rate capability and cycling stability, its specific capacitance is maintained at 70% as the current densities increase from 1 to 20 A g-1 and 85% at a current density of 10 A g-1 after 10 000 cycles. More importantly, the MNN/IL-GP displays distinguished mechanical stability and flexibility for device packaging, although its thickness is merely 8 μm. These features collectively demonstrate the potential of MNN/IL-GP as a high-performance paper electrode for flexible and lightweight and highly efficient electrochemical capacitor applications.A sandwich-structured flexible supercapacitor electrode has been developed based on MnO2 nanonest (MNN) modified ionic liquid (IL) functionalized graphene paper (GP), which is fabricated by functionalizing graphene nanosheets with an amine-terminated IL (i.e., 1-(3-aminopropyl)-3-methylimidazolium bromide) to form freestanding IL functionalized GP (IL-GP), and then modifying IL-GP with a unique MNN structure via controllable template-free ultrasonic electrodeposition. The as-obtained MNN modified IL-GP (MNN/IL-GP) inherits the excellent

  9. Aberrant function of learning and cognitive control networks underlie inefficient cognitive flexibility in anorexia nervosa: a cross-sectional fMRI study.

    Science.gov (United States)

    Lao-Kaim, Nick P; Fonville, Leon; Giampietro, Vincent P; Williams, Steven C R; Simmons, Andrew; Tchanturia, Kate

    2015-01-01

    People with Anorexia Nervosa exhibit difficulties flexibly adjusting behaviour in response to environmental changes. This has previously been attributed to problematic behavioural shifting, characterised by a decrease in fronto-striatal activity. Additionally, alterations of instrumental learning, which relies on fronto-striatal networks, may contribute to the observation of inflexible behaviour. The authors sought to investigate the neural correlates of cognitive flexibility and learning in Anorexia Nervosa. Thirty-two adult females with Anorexia Nervosa and thirty-two age-matched female control participants completed the Wisconsin Card Sorting Task whilst undergoing functional magnetic resonance imaging. Event-related analysis permitted the comparison of cognitive shift trials against those requiring maintenance of rule-sets and allowed assessment of trials representing learning. Although both groups performed similarly, we found significant interactions in the left middle frontal gyrus, precuneus and superior parietal lobule whereby blood-oxygenated-level dependent response was higher in Anorexia Nervosa patients during shifting but lower when maintaining rule-sets, as compared to healthy controls. During learning, posterior cingulate cortex activity in healthy controls decreased whilst increasing in the Anorexia Nervosa group, whereas the right precuneus exhibited the opposite pattern. Furthermore, learning was associated with lower blood-oxygenated-level dependent response in the caudate body, as compared to healthy controls. People with Anorexia Nervosa display widespread changes in executive function. Whilst cognitive flexibility appears to be associated with aberrant functioning of the fronto-parietal control network that mediates between internally and externally directed cognition, fronto-striatal alterations, particularly within the caudate body, were associated with instrumental learning. Together, this shows how perseverative tendencies could be a

  10. Brain natriuretic peptide as a predictor of heart failure in patients with permanent pacemaker

    Directory of Open Access Journals (Sweden)

    Jelić Vera

    2007-01-01

    Full Text Available Introduction: Brain natriuretic peptide (BNP has a role in control of cardiovascular and renal functions. Objective The objective was to assess the predictive value of BNP levels for development of heart failure in patients with permanent pacemakers. Method In patients with implanted DDD pacemakers, BNP levels were measured at rest and after exercise testing, on DDD and VVI modes. There were 42 patients (25 males; 59.5%, without symptoms or signs of coronary disease or heart failure, and with normal echocardiograms. According to BNP levels, the patients were divided into three groups: with BNP levels lower than 80 pg/ml, BNP ranging from 81-150 pg/ml, and BNP levels over 151 pg/ml. Results In the first group (27 patients, BNP levels were significantly higher on VVI compared to DDD mode, both at rest and after exercise (p<0.01, with all BNP levels within normal range. In the second group (5 pts, BNP levels at rest were also significantly higher on VVI than on DDD mode, p<0.05. After exercise, these values were also higher on VVI compared to DDD mode, but without statistical significance. The third group (10 pts as a whole had higher BNP values on VVI compared to DDD mode, with no statistical significance. In patients from this group who later developed heart failure, BNP levels were found to be significantly lower on DDD as opposed to VVI mode at rest, p<0.05, and even higher significance was found after exercise, p<0.01. After 6-year follow-up, 2 out of 5 patients from the second group developed dilated cardiomyopathy, and 8/10 patients in the third group experienced heart failure with LV EF 34.1±10%, LV EDD 6.1±0.42 cm, LV ESD 4.8±0.45 cm. Five of these patients died within the follow-up period. Conclusion The increased BNP levels can be valuable for early screening of patients with higher risk of heart failure. In patients with increased BNP at the time of pacemaker implantation, DDD pacing is a modality of choice.

  11. Flexibility conflict?

    NARCIS (Netherlands)

    Delsen, L.W.M.

    2002-01-01

    The chapter deals with the presupposed conflict of interests between employers and employees resulting from a decoupling of operating hours and working times. It starts from the notion that both long operating hours and flexibility are relative concepts. As there is some discretion, the ultimate

  12. Flexible Consumption

    DEFF Research Database (Denmark)

    Holm Jacobsen, Peter; Pallesen, Trine

    This report presents the first findings from our qualitative study of consumer behaviour vis-à-vis flexible consumption. The main of objective of this report is to present our first round of data from Bornholm, and to assist the design of products/services designed in WP6. In the report, we adopt...

  13. Dental treatment in patients with cardiac pacemakers: Is it a risky affair?

    Directory of Open Access Journals (Sweden)

    Reet Kamal

    2016-01-01

    Full Text Available Cardiac pacemakers are the implanted devices used to treat patients with damaged heart muscles. These electronic devices are sensitive to strong electromagnetic signals. The dental literature also included articles regarding electromagnetic interferences to pacemakers, due to dental devices such as ultrasonic scalers, electrosurgical unit, ultrasonic bath cleaners, and battery driven light cure composite unit. Although pacemakers of new generation have more protective features than those of past, but still precautionary measures should be taken in dental clinics for the safety of cardiac patients with pacemaker. The aim of this paper is to identify the possible sources from dental clinics which can adversely interfere with the pacemaker activity and to provide some guidelines for safe dental practice in this high-risk group.

  14. Popeye domain-containing proteins and stress-mediated modulation of cardiac pacemaking.

    Science.gov (United States)

    Simrick, Subreena; Schindler, Roland F; Poon, Kar-Lai; Brand, Thomas

    2013-10-01

    An intricate network of ion channels and pumps are involved in generating a diastolic pacemaker potential, which is transmitted to the working myocardium with the help of the cardiac conduction system. The principles of cardiac pacemaking are reasonably well understood, however, the mechanism by which the heart increases its beating frequency in response to adrenergic stimulation has not been fully worked out. The Popeye domain-containing (Popdc) genes encode plasma membrane-localized proteins that are able to bind cAMP with high affinity; mice with null mutations in Popdc1 or 2 have a stress-induced pacemaker dysfunction. The phenotype in both mutants develops in an age-dependent manner and thus may model pacemaker dysfunction in man, as well as provide novel mechanistic insights into the process of pacemaker adaptation to stress.

  15. Pacemaker Created in Human Ventricle by Depressing Inward-Rectifier K+ Current: A Simulation Study

    Science.gov (United States)

    Zhang, Yue; Li, Qince; Zhang, Henggui

    2016-01-01

    Cardiac conduction disorders are common diseases which cause slow heart rate and syncope. The best way to treat these diseases by now is to implant electronic pacemakers, which, yet, have many disadvantages, such as the limited battery life and infection. Biopacemaker has been expected to replace the electronic devices. Automatic ventricular myocytes (VMs) could show pacemaker activity, which was induced by depressing inward-rectifier K+ current (IK1). In this study, a 2D model of human biopacemaker was created from the ventricular endocardial myocytes. We examined the stability of the created biopacemaker and investigated its driving capability by finding the suitable size and spatial distribution of the pacemaker for robust pacing and driving the surrounding quiescent cardiomyocytes. Our results suggest that the rhythm of the pacemaker is similar to that of the single cell at final stable state. The driving force of the biopacemaker is closely related to the pattern of spatial distribution of the pacemaker. PMID:26998484

  16. Pacemaker Created in Human Ventricle by Depressing Inward-Rectifier K+ Current: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Yue Zhang

    2016-01-01

    Full Text Available Cardiac conduction disorders are common diseases which cause slow heart rate and syncope. The best way to treat these diseases by now is to implant electronic pacemakers, which, yet, have many disadvantages, such as the limited battery life and infection. Biopacemaker has been expected to replace the electronic devices. Automatic ventricular myocytes (VMs could show pacemaker activity, which was induced by depressing inward-rectifier K+ current (IK1. In this study, a 2D model of human biopacemaker was created from the ventricular endocardial myocytes. We examined the stability of the created biopacemaker and investigated its driving capability by finding the suitable size and spatial distribution of the pacemaker for robust pacing and driving the surrounding quiescent cardiomyocytes. Our results suggest that the rhythm of the pacemaker is similar to that of the single cell at final stable state. The driving force of the biopacemaker is closely related to the pattern of spatial distribution of the pacemaker.

  17. Identifying transitions in finite systems by means of partition function zeros and microcanonical inflection-point analysis: A comparison for elastic flexible polymers

    CERN Document Server

    Rocha, Julio C S; Landau, David P; Bachmann, Michael

    2014-01-01

    For the estimation of transition points of finite elastic, flexible polymers with chain lengths from $13$ to $309$ monomers, we compare systematically transition temperatures obtained by the Fisher partition function zeros approach with recent results from microcanonical inflection-point analysis. These methods rely on accurate numerical estimates of the density of states, which have been obtained by advanced multicanonical Monte Carlo sampling techniques. Both the Fisher zeros method and microcanonical inflection-point analysis yield very similar results and enable the unique identification of transition points in finite systems, which is typically impossible in the conventional canonical analysis of thermodynamic quantities.

  18. E and M circadian pacemaker neurons use different PDF receptor signalosome components in drosophila.

    Science.gov (United States)

    Duvall, Laura B; Taghert, Paul H

    2013-08-01

    We used real-time imaging to detect cAMP levels in neurons of intact fly brains to study the mechanisms of circadian pacemaker synchronization by the neuropeptide pigment dispersing factor (PDF) in Drosophila. PDF receptor (PDF-R) is expressed by both M (sLNv) and E (LNd) pacemaker subclasses and is coupled to G(sα) in both cases. We previously reported that PDF-R in M pacemakers elevates cAMP levels by activating the ortholog of mammalian adenylate cyclase 3 (AC3) but that AC3 disruptions had no effect on E pacemaker sensitivity to PDF. Here, we show that PDF-R in E pacemakers activates a different AC isoform, AC78C, an ortholog of mammalian AC8. Knockdown of AC78C by transgenic RNAi substantially reduces, but does not completely abrogate, PDF responses in these E pacemakers. The knockdown effect is intact when restricted to mature stages, suggesting a physiological and not a development role for AC78C in E pacemakers. The AC78C phenotype is rescued by the overexpression of AC78C but not by overexpression of the rutabaga AC. AC78C overexpression does not disrupt PDF responses in these E pacemakers, and neither AC78C knockdown nor its overexpression disrupted locomotor rhythms. Finally, knockdown of 2 AKAPs, nervy and AKAP200, partially reduces LNd PDF responses. These findings begin to identify the components of E pacemaker PDF-R signalosomes and indicate that they are distinct from PDF-R signalosomes in M pacemakers: we propose they contain AC78C and at least 1 other AC.

  19. Complications of pacemaker therapy in adults with congenital heart disease: a multicenter study.

    Science.gov (United States)

    Opić, Petra; van Kranenburg, Matthijs; Yap, Sing-Chien; van Dijk, Arie P; Budts, Werner; Vliegen, Hubert W; van Erven, Lieselot; Can, Anil; Sahin, Gulhan; Theuns, Dominic A M J; Witsenburg, Maarten; Roos-Hesselink, Jolien W

    2013-10-09

    This study aims to investigate indications and complications of permanent cardiac pacing in adults with congenital heart disease (CHD). Two-hundred and seventy-four CHD patients were identified who underwent permanent pacemaker implantation between 1972 and 2009. The indication for pacing was acquired sinus node or AV node conduction disease (63%), sinus node or AV node conduction disease after cardiac surgery (28%), and drug/arrhythmia-related indications (9%). Patients with complex CHD received a pacemaker at younger age (23 versus 31 years, ppacemaker implantation (general population: 5.2%). The most common acute complications were lead dysfunction (4.0%), bleeding (2.6%), pocket infection (1.5%) and pneumothorax (1.5%). During a median follow-up of 12 years, pacemaker-related complications requiring intervention occurred in 95 patients (34.6%). The most common late pacemaker-related complications included lead failure (24.8%), pacemaker dysfunction/early battery depletion (5.1%), pacemaker migration (4.7%) and erosion (4.7%). Pacemaker implantation at younger age (pacemaker-related complication (adjusted hazard ratio 1.68, 95% confidence interval 1.07 to 2.63, p=0.023). The risk of periprocedural complications seems higher in the CHD population compared to the general population and more than one-third of CHD patients encountered a pacemaker-related complication during long-term follow-up. This risk increases for those who receive a pacemaker at younger age. Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

  20. Iterative Knowledge-Based Scoring Functions Derived from Rigid and Flexible Decoy Structures: Evaluation with the 2013 and 2014 CSAR Benchmarks.

    Science.gov (United States)

    Yan, Chengfei; Grinter, Sam Z; Merideth, Benjamin Ryan; Ma, Zhiwei; Zou, Xiaoqin

    2016-06-27

    In this study, we developed two iterative knowledge-based scoring functions, ITScore_pdbbind(rigid) and ITScore_pdbbind(flex), using rigid decoy structures and flexible decoy structures, respectively, that were generated from the protein-ligand complexes in the refined set of PDBbind 2012. These two scoring functions were evaluated using the 2013 and 2014 CSAR benchmarks. The results were compared with the results of two other scoring functions, the Vina scoring function and ITScore, the scoring function that we previously developed from rigid decoy structures for a smaller set of protein-ligand complexes. A graph-based method was developed to evaluate the root-mean-square deviation between two conformations of the same ligand with different atom names and orders due to different file preparations, and the program is freely available. Our study showed that the two new scoring functions developed from the larger training set yielded significantly improved performance in binding mode predictions. For binding affinity predictions, all four scoring functions showed protein-dependent performance. We suggest the development of protein-family-dependent scoring functions for accurate binding affinity prediction.

  1. Flexible isotopy classification of flexible links

    OpenAIRE

    Björklund, Johan

    2012-01-01

    In this paper we define and study flexible links and flexible isotopy in projective space. Flexible links are meant to capture the topological properties of real algebraic links. We classify all flexible links up to flexible isotopy using Ekholms interpretation of Viros encomplexed writhe.

  2. The missing link in the mystery of normal automaticity of cardiac pacemaker cells.

    Science.gov (United States)

    Lakatta, Edward G; Vinogradova, Tatiana M; Maltsev, Victor A

    2008-03-01

    Earlier studies of the initiating event of normal automaticity of the heart's pacemaker cells, inspired by classical quantitative membrane theory, focused upon ion currents (IK, I f) that determine the maximum diastolic potential and the early phase of the spontaneous diastolic depolarization (DD). These early DD events are caused by the prior action potential (AP) and essentially reflect a membrane recovery process. Events following the recovery process that ignite APs have not been recognized and remained a mystery until recently. These critical events are linked to rhythmic intracellular signals initiated by Ca2+ clock (i.e., sarcoplasmic reticulum [SR] cycling Ca2+). Sinoatrial cells, regardless of size, exhibit intense ryanodine receptor (RyR), Na+/Ca2+ exchange (NCX)-1, and SR Ca2+ ATPase-2 immunolabeling and dense submembrane NCX/RyR colocalization; Ca2+ clocks generate spontaneous stochastic but roughly periodic local subsarcolemmal Ca2+ releases (LCR). LCRs generate inward currents via NCX that exponentially accelerate the late DD. The timing and amplitude of LCR/I NCX-coupled events control the timing and amplitude of the nonlinear terminal DD and therefore ultimately control the chronotropic state by determining the timing of the I CaL activation that initiates the next AP. LCR period is precisely controlled by the kinetics of SR Ca2+ cycling, which, in turn, are regulated by 1) the status of protein kinase A-dependent phosphorylation of SR Ca2+ cycling proteins; and 2) membrane ion channels ensuring the Ca2+ homeostasis and therefore the Ca2+ available to Ca2+ clock. Thus, the link between early DD and next AP, missed in earlier studies, is ensured by a precisely physiologically regulated Ca2+ clock within pacemaker cells that integrates multiple Ca2+-dependent functions and rhythmically ignites APs during late DD via LCRs-I NCX coupling.

  3. Flexible Capitalism

    DEFF Research Database (Denmark)

    Approaching “work” as at heart a practice of exchange, this volume explores sociality in work environments marked by the kind of structural changes that have come to define contemporary “flexible” capitalism. It introduces anthropological exchange theory to a wider readership, and shows how...... the perspective offers new ways to enquire about the flexible capitalism’s social dimensions. The essays contribute to a trans-disciplinary scholarship on contemporary economic practice and change by documenting how, across diverse settings, “gift-like” socialities proliferate, and even sustain the intensified...... flexible commoditization that more commonly is touted as tearing social relations apart. By interrogating a keenly debated contemporary work regime through an approach to sociality rooted in a rich and distinct anthropological legacy, the volume also makes a novel contribution to the anthropological...

  4. Pyloric obstruction secondary to epicardial pacemaker implantation: a case report.

    Science.gov (United States)

    Bedoya Nader, G; Kellihan, H B; Bjorling, D E; McAnulty, J

    2017-02-01

    A 10-year old Lhasa Apso dog was presented for an acute history of exercise intolerance and hind limb weakness. High grade second degree atrioventricular block with an atrial rate of 200 beats per minute, ventricular rate of 40 beats per minute and an intermittent ventricular escape rhythm, was diagnosed on electrocardiograph. A transdiaphragmatic, unipolar, epicardial pacemaker was implanted without immediate surgical complications. Severe vomiting was noted 12 h post-operatively. Abdominal ultrasound and a barium study supported a diagnosis of pyloric outflow obstruction and exploratory abdominal surgery was performed. The pyloric outflow tract appeared normal and no other causes of an outflow obstruction were identified. The epicardial generator was repositioned from the right to the left abdominal wall. Pyloric cell pacing was presumed to be the cause for the pyloric obstruction and severe vomiting, and this was thought to be due to close proximity of the pacemaker generator to the pylorus situated in the right abdominal wall. Repositioning of the pulse generator to the left abdominal wall resulted in resolution of vomiting. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Pacemaker dynamics in the full Morris-Lecar model

    Science.gov (United States)

    González-Miranda, J. M.

    2014-09-01

    This article reports the finding of pacemaker dynamics in certain region of the parameter space of the three-dimensional version of the Morris-Lecar model for the voltage oscillations of a muscle cell. This means that the cell membrane potential displays sustained oscillations in the absence of an external electrical stimulation. The development of this dynamic behavior is shown to be tied to the strength of the leak current contained in the model. The approach followed is mostly based on the use of linear stability analysis and numerical continuation techniques. In this way it is shown that the oscillatory dynamics is associated to the existence of two Hopf bifurcations, one subcritical and other supercritical. Moreover, it is explained that in the region of parameter values most commonly studied for this model such pacemaker dynamics is not displayed because of the development of two fold bifurcations, with the increase of the strength of the leak current, whose interaction with the Hopf bifurcations destroys the oscillatory dynamics.

  6. Functional Surface Coating on Cellulosic Flexible Substrates with Improved Water-Resistant and Antimicrobial Properties by Use of ZnO Nanoparticles

    Directory of Open Access Journals (Sweden)

    Xiaofei Tian

    2017-01-01

    Full Text Available It is of significant interest to create functional flexible surfaces that simultaneously exhibit high water-resistance and antimicrobial performances for medical or packaging applications. This study reported a synthesis of functional surface coating on flexible cellulose materials (filter papers with ZnO nanoparticles and binds of renewable soybean oil-based polymers. Self-aggregation of ZnO nanoparticles could form ZnO particles with two regular morphological patterns. Rather than a rod-like morphology, a flower-like ZnO benefited a promotion of surface hydrophobicity. Moreover, surface with the flower-like ZnO showed a 51.6% promotion on antimicrobial activities against Gram-negative bacteria (E. coli than the rod-like ZnO. A low binder/ZnO ratio of 0.2 led to a remarkable improvement on water repelling performances without negative effects on a coating adhesion of ZnO. Under this condition, a hydrophobic surface was achieved with a large static contact angle of 138° when applying ZnO nanoparticles at a dosage of 3 g m−2.

  7. Flexible Coupling Corrects Shaft Misalinements

    Science.gov (United States)

    Mayo, R. A.

    1983-01-01

    Proposed flexible coupling provides nearly error free measurements of shaft rotation in presence of misalinements between shaft and position sensing transducer. Intended to be used in situations in which input or output shaft is mounted on flexible joint. Its function is to insure equal input and output angular velocities by forcing input and output shafts to remain parallel.

  8. Transvenous permanent pacemaker implantation in dextrocardia: technique, challenges, outcome, and a brief review of literature.

    Science.gov (United States)

    Shenthar, Jayaprakash; Rai, Maneesh K; Walia, Rohit; Ghanta, Somasekhar; Sreekumar, Praveen; Reddy, Satish S

    2014-09-01

    Dextrocardia is a rare congenital anomaly. Pacemaker implantation in dextrocardia can be challenging because of the distorted anatomy and associated anomalies. The literature regarding implantation of pacemaker in dextrocardia is scarce. The study involved retrospective analysis of records of patients with dextrocardia who had undergone pacemaker implantation between January 2006 and July 2013 from a single centre. Six patients with dextrocardia (five males and one female) underwent permanent pacemaker implantation (PPI) between January 2006 and July 2013. Of them, three had situs solitus dextrocardia and three situs inversus dextrocardia. All three patients with situs solitus dextrocardia had associated corrected transposition of great arteries. The indication for pacemaker implantation was symptomatic complete atrioventricular (AV) block in four, high-grade AV block in one, and sinus node dysfunction in one patient. A favourable outcome was noted during a mean follow-up of 3.9 years (4 months to 7 years) with one patient needing a pulse generator replacement. Permanent pacemaker implantation in dextrocardia can be challenging because of the distorted anatomy. Use of a technique employing angiography to delineate chamber anatomy and relationship can assist the operator during such difficult PPIs. The medium- and long-term survival after a successful pacemaker implantation in dextrocardia is favourable. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  9. Outcome and management of pacemaker-induced superior vena cava syndrome.

    Science.gov (United States)

    Fu, Hai-Xia; Huang, Xin-Miao; Zhong, Li; Osborn, Michael J; Bjarnason, Haraldur; Mulpuru, Siva; Zhao, Xian-Xian; Friedman, Paul A; Cha, Yong-Mei

    2014-11-01

    We aimed to determine the long-term outcomes of percutaneous lead extraction and stent placement in patients with pacemaker-induced superior vena cava (SVC) syndrome. The study retrospectively screened patients who underwent lead extraction followed by central vein stent implantation at Mayo Clinic (Rochester, MN, USA), from January 2005 to December 2012, to identify the patients with pacemaker-induced SVC syndrome. Demographic, clinical, and follow-up characteristics of those patients were collected from electronic medical records. Six cases were identified. The mean (standard deviation) age was 56 (15) years (male, 67%). All patients had permanent dual-chamber pacemakers, with a mean 11-year history of pacemaker placement. The entire device system was explanted in five patients; one patient had a 21-year-old pacemaker lead that could not be removed. Eight stents were implanted in six patients: five patients had one stent, one patient had three. A new pacemaker system was reimplanted through the stented vein in five patients. Technical success was achieved in all patients, without any complication. Symptoms rapidly resolved in all patients after stent deployment. The mean follow-up duration was 48 months (range, 10-100 months). Three patients remained symptom free. Reintervention with percutaneous balloon venoplasty was successful in three patients with symptom recurrence. Percutaneous stent implantation after lead removal followed by reimplantation of leads is a feasible alternative therapy for pacemaker-induced SVC syndrome, although some cases may require repeat intervention. ©2014 Wiley Periodicals, Inc.

  10. Rhabdomyosarcoma associated with the lead wire of a pacemaker generator implant.

    Science.gov (United States)

    Thieman Mankin, Kelley M; Dunbar, Mark D; Toplon, David; Ginn, Pamela; Maisenbacher, Herbert W; Risselada, Marije

    2014-06-01

    An 11-year-old female spayed Labrador Retriever was presented for a draining, painful subcutaneous mass palpated over a previously implanted pacemaker generator. Infection was suspected and the mass was removed surgically. On cut surface, the mass was friable and mottled tan to brown with firm pale tan nodules, surrounding the pacemaker lead wire adjacent to the pacemaker generator. Cytologic interpretation of impression smears was consistent with a sarcoma, and suggestive of a rhabdomyosarcoma due to the presence of strap-like cells. On histopathologic examination, a highly invasive nodular mass surrounded the pacemaker lead, composed of pleomorphic round, spindle and strap cells, and multinucleated giant cells. The population exhibited microscopic invasion into the deep portion of the fibrous capsule surrounding the pacemaker generator. There were tumor emboli within small to medium subcutaneous veins adjacent to the mass. Immunohistochemically, the neoplastic cells stained positive for α-sarcomeric actin and vimentin, and negative for α-smooth muscle actin, consistent with a rhabdomyosarcoma arising at the site of the pacemaker generator. To our knowledge, this is the first report of a rhabdomyosarcoma associated with the lead wire of a pacemaker generator in a dog. © 2014 American Society for Veterinary Clinical Pathology and European Society for Veterinary Clinical Pathology.

  11. Predictors for permanent pacemaker implantation after concomitant surgical ablation for atrial fibrillation.

    Science.gov (United States)

    Pecha, Simon; Schäfer, Timm; Yildirim, Yalin; Ahmadzade, Teymour; Willems, Stephan; Reichenspurner, Hermann; Wagner, Florian Mathias

    2014-03-01

    Concomitant surgical atrial fibrillation (AF) ablation is a safe and feasible procedure, recommended in guidelines. Pacemaker dependency is a known complication of AF ablation. We sought to determine independent predictors for pacemaker implantation after surgical AF ablation. Between January 2003 and November 2012, 594 patients underwent concomitant surgical AF ablation. Various energy sources, including cryoablation (n = 139), unipolar radiofrequency (n = 278), and bipolar radiofrequency (n = 177), were used. Left atrial (n = 463, 77.9%) and biatrial (n = 131, 22.1%) ablation was performed. Univariate and multivariate logistic regression analysis was used to identify independent predictors for pacemaker implantation within 30 days after surgical AF ablation. The mean patient's age was 68.6 ± 9.4 years, and 66.8% were male. No major ablation-related complications occurred. A total of 41 (6.9%) of patients received pacemaker implantation during the 30-day follow-up period. Indications for pacemaker implantation were atrioventricular block in 25 (60.9%) of patients, sinus bradycardia or sinus arrest in 9 (22.0%) of patients, and bradyarrhythmia in 7 (17.1%) of patients. Demographic data, type of surgical procedure, and type of energy source did not have a significant impact on pacemaker implantation rate. However, biatrial ablation led to a significant pacemaker implantation rate compared with isolated left-sided ablation (6.3% vs 13.6%; P = .028). Concomitant surgical AF ablation showed a pacemaker implantation rate of 6.9% after 30-day follow-up. Univariate and multivariate analysis showed biatrial lesion set as the only statistically significant predictor for pacemaker implantation after surgical AF ablation. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  12. Overlay of semi-dried functional layers in offset printing for rapid and high-precision fabrication of flexible TFTs

    Science.gov (United States)

    Kusaka, Yasuyuki; Sugihara, Kazuyoshi; Koutake, Masayoshi; Ushijima, Hirobumi

    2014-03-01

    We achieved a reduction in the misregistration of overlying patterns printed on a flexible plastic film and a drastically shorter processing time with fully printed thin-film transistor (TFT) fabrication. This was achieved using a newly developed wet-on-wet (WoW) printing process wherein a subsequent layer can be printed on a previous semi-dried (not-sintered) layer. In the WoW process, as examined by rheological measurements, a semi-dried (highly solidified) state of ink was attained before transferring by utilizing the solvent uptake of a PDMS blanket in offset printing to ensure the structural integrity of the ink layer, and to reduce the inter-contamination of adjoining layers. Loss-on-drying tests and resistivity measurements indicated that molecular penetration at the boundary of adjoining layers with a length of c.a. 70 nm occurred in the WoW process; however, with thicker electrodes, we successfully fabricated a WoW-processed TFT whose performance was comparable with a TFT formed by a conventional printing process.

  13. 咪唑啉/α2受体激动剂对兔窦房结起博细胞的电生理效应%Electrophysiological responses to imidazoline/α2-receptor agonists in rabbit sinoatrial node pacemaker cells

    Institute of Scientific and Technical Information of China (English)

    赵丁; 任雷鸣

    2003-01-01

    AIM: To compare the effects of moxonidine (Mox), clonidine (Clo), agmatine (Agm), and xylazine (Xyl) on action potentials (AP) of the rabbit sinoatrial node (SAN) pacemaker cells and investigate the contribution of α-adrenoceptors to the cardiac electrophysiologic responses induced by the agonists. METHODS: Intracellular microelectrode technique was used to record AP in the rabbit SAN pacemaker cells. Vasoconstrictive responses to norepinephrine (NE), Mox, Clo, Agm and Xyl were observed in the thoracic aorta and ear vein isolated from rabbits. RESULTS: (1) In the rabbit thoracic aorta, a rank order of potency producing vasoconstrictive responses was NE>Clo>Mox;and a rank order of potency in ear vein was Clo>NE>Xyl=Mox. Agm did not produce any vascular responses in both preparations, and Xyl did not produce vascular responses in the thoracic aorta. (2) Mox, Clo, Xyl, and Agm concentration-dependently decreased the rate of pacemaker firing (RPF), and prolonged APD50 and APD90 in the rabbit SAN pacemaker cells. The rank order of decreasing RPF or prolonging APD was Clo>Xyl=Mox. (3) Most effects of Clo were partially inhibited by yohimbine, but those of Xyl and all the effects of Agm on the AP in SAN pacemaker cells were not affected by the treatment with yohimbine. (4) In the presence of propranolol 1 μmol/L, phenylephrine did not cause any effects on AP in the rabbit SAN pacemaker cells. CONCLUSION: Like Mox, Clo changes AP of the rabbit SAN pacemaker cells via α2-adrenoceptors partially, but the effects of Xyl and Agm on the AP are almost not related to α2-adrenoceptors. Moreover, there are no obviously functional α1-adrenoceptors in the rabbit SAN pacemaker cells.

  14. Ventricular oversensing of atrial electrical activity that inhibits VVI pacemaker and causes syncope

    Directory of Open Access Journals (Sweden)

    Elibet Chávez González

    2015-10-01

    Full Text Available Far-field oversensing of atrial electrical activity caused by a VVI pacemaker is a rare phenomenon; however, it may have serious clinical consequences. It has several causes and its timely identification may avoid a possible ventricular asystole. This article reports the case of a 72-year-old male who had a Biotronik Axios SR pacemaker implanted, in VVIR mode, six years ago, due to blocked atrial fibrillation. He suffered syncope due to pacemaker inhibition caused by ventricular oversensing of atrial electrical activity.

  15. Subjective consequences of permanent pacemaker therapy in patients under the age of retirement

    DEFF Research Database (Denmark)

    Mickley, H; Petersen, J; Nielsen, B L

    1989-01-01

    or a sensation of "impulses"/palpitations. To the majority (49 patients or 68.1%) pacemaker treatment did not influence quality of sexual activity. Six patients (8.3%) perceived an improvement, whereas a corresponding number felt deterioration in sexual activity following pacemaker implantation. Pacemaker...... pronounced in subjects suffering from syncope and/or dizziness. Eight patients (11.1%) perceived anxiety most frequently due to fear of pacing failure. Physical complaints were present in 17 patients (23.6%), and the discomfort was mainly due to the size of generator, pain/tenderness from the scar...

  16. Flexible Capitalism

    DEFF Research Database (Denmark)

    Approaching “work” as at heart a practice of exchange, this volume explores sociality in work environments marked by the kind of structural changes that have come to define contemporary “flexible” capitalism. It introduces anthropological exchange theory to a wider readership, and shows how...... the perspective offers new ways to enquire about the flexible capitalism’s social dimensions. The essays contribute to a trans-disciplinary scholarship on contemporary economic practice and change by documenting how, across diverse settings, “gift-like” socialities proliferate, and even sustain the intensified...

  17. Periodically-modulated inhibition of living pacemaker neurons--III. The heterogeneity of the postsynaptic spike trains, and how control parameters affect it.

    Science.gov (United States)

    Segundo, J P; Vibert, J F; Stiber, M

    1998-11-01

    synaptic codings, present always but in each case distorted typically. (2) Synapses are prototype: similar behaviours should be widespread, and networks simulations benefit by nonlinear units generating all forms. (3) Relevant to periodic functions are that few variables need be involved in form selection, that distortions are susceptible to noise levels and, if periods are heterogeneous, that simple input cycles impose heterogeneous outputs. (4) Slow Na inactivations are necessary for obtaining complex forms and hysteresis. Formal significance--(1) Pacemaker-driven forms and presumably their modulation-driven counterparts, pertain to universal periodic, intermittent, quasiperiodic and chaotic categories whose formal properties carry physiological connotations. (2) Only relatively elaborate, nonlinear geometric models show all forms; simpler ones, show only alternations and walk-throughs. (3) Bifurcations resemble those of simple maps that can provide useful guidelines. (4) Heterogeneity poses the unanswered question of whether or not the entire cycle and all portions have the same behaviours: therefore, whether trajectories are continuous or have discontinuities and/or singular points.

  18. A C-terminal Hydrophobic, Solvent-protected Core and a Flexible N-terminus are Potentially Required for Human Papillomavirus 18 E7 Protein Functionality

    Energy Technology Data Exchange (ETDEWEB)

    Liu, S.; Tian, Y; Greenaway, F; Sun, M

    2010-01-01

    The oncogenic potential of the high-risk human papillomavirus (HPV) relies on the expression of genes specifying the E7 and E6 proteins. To investigate further the variation in oligomeric structure that has been reported for different E7 proteins, an HPV-18 E7 cloned from a Hispanic woman with cervical intraepithelial neoplasia was purified to homogeneity most probably as a stable monomeric protein in aqueous solution. We determined that one zinc ion is present per HPV-18 E7 monomer by amino acid and inductively coupled plasma-atomic emission spectroscopy analysis. Intrinsic fluorescence and circular dichroism spectroscopic results indicate that the zinc ion is important for the correct folding and thermal stability of HPV-18 E7. Hydroxyl radical mediated protein footprinting coupled to mass spectrometry and other biochemical and biophysical data indicate that near the C-terminus, the four cysteines of the two Cys-X{sub 2}-Cys motifs that are coordinated to the zinc ion form a solvent inaccessible core. The N-terminal LXCXE pRb binding motif region is hydroxyl radical accessible and conformationally flexible. Both factors, the relative flexibility of the pRb binding motif at the N-terminus and the C-terminal metal-binding hydrophobic solvent-protected core, combine together and facilitate the biological functions of HPV-18 E7.

  19. Imidazolium-Functionalized Poly(arylene ether sulfone) Anion-Exchange Membranes Densely Grafted with Flexible Side Chains for Fuel Cells.

    Science.gov (United States)

    Guo, Dong; Lai, Ao Nan; Lin, Chen Xiao; Zhang, Qiu Gen; Zhu, Ai Mei; Liu, Qing Lin

    2016-09-28

    With the intention of optimizing the performance of anion-exchange membranes (AEMs), a set of imidazolium-functionalized poly(arylene ether sulfone)s with densely distributed long flexible aliphatic side chains were synthesized. The membranes made from the as-synthesized polymers are robust, transparent, and endowed with microphase segregation capability. The ionic exchange capacity (IEC), hydroxide conductivity, water uptake, thermal stability, and alkaline resistance of the AEMs were evaluated in detail for fuel cell applications. Morphological observation with the use of atomic force microscopy and small-angle X-ray scattering reveals that the combination of high-local-density-type and side-chain-type architectures induces distinguished nanophase separation in the AEMs. The as-prepared membranes have advantages in effective water management and ionic conductivity over traditional main-chain polymers. Typically, the conductivity and IEC were in the ranges of 57.3-112.5 mS cm(-1) and 1.35-1.84 mequiv g(-1) at 80 °C, respectively. Furthermore, the membranes exhibit good thermal and alkaline stability and achieve a peak power density of 114.5 mW cm(-2) at a current density of 250.1 mA cm(-2). Therefore, the present polymers containing clustered flexible pendent aliphatic imidazolium promise to be attractive AEM materials for fuel cells.

  20. Nonlinear oscillations in a muscle pacemaker cell model

    Science.gov (United States)

    González-Miranda, J. M.

    2017-02-01

    This article presents a numerical simulation study of the nonlinear oscillations displayed by the Morris-Lecar model [Biophys. J. 35 (1981) 193] for the oscillations experimentally observed in the transmembrane potential of a muscle fiber subject to an external electrical stimulus. We consider the model in the case when there is no external stimulation, aiming to establish the ability of the model to display biophysically reasonable pacemaker dynamics. We obtain 2D bifurcation diagrams showing that indeed the model presents oscillatory dynamics, displaying the two main types of action potentials that are observed in muscle fibers. The results obtained are shown to be structurally stable; that is, robust against changes in the values of system parameters. Moreover, it is demonstrated how the model is appropriate to analyze the action potentials observed in terms of the transmembrane currents creating them.

  1. Percutaneously injectable fetal pacemaker: electronics, pacing thresholds, and power budget.

    Science.gov (United States)

    Nicholson, Adriana; Chmait, Ramen; Bar-Cohen, Yaniv; Zheng, Kaihui; Loeb, Gerald E

    2012-01-01

    We are developing a cardiac pacemaker that is designed to be implanted percutaneously into a fetus to treat complete heart block and consequent hydrops fetalis, which is otherwise fatal. One of the most significant considerations for this device is the technical challenges presented by the battery and charging system. The size of the device is limited to about 3 mm in diameter; batteries on this scale have very small charge capacities. The smaller capacity means that the device needs to be designed so that it uses as little current as possible and so that its battery can be recharged wirelessly. We determined the pacing thresholds for a simple relaxation oscillator that can be assembled from discrete, surface mount components and analyzed the power consumption of the device given different electrode configurations and stimulus parameters. An inductive recharging system will be required for some patients; it is feasible within the package constraints and under development.

  2. Analysis of a five year experience of permanent pacemaker implantation at a Nigerian Teaching Hospital: need for a national database.

    Science.gov (United States)

    Falase, Bode; Sanusi, Michael; Johnson, Adeyemi; Akinrinlola, Fola; Ajayi, Reina; Oke, David

    2013-01-01

    Permanent pacemaker implantation is available in Nigeria. There is however no national registry or framework for pacemaker data collection. A pacemaker database has been developed in our institution and the results are analyzed in this study. The study period was between January 2008 and December 2012. Patient data was extracted from a prospectively maintained database which was designed to include the fields of the European pacemaker patient identification code. Of the 51 pacemaker implants done, there were 29 males (56.9%) and 22 females (43.1%). Mean age was 68.2±12.7 years. Clinical indications were syncopal attacks in 25 patients (49%), dizzy spells in 15 patients (29.4%), bradycardia with no symptoms in 10 patients (17.7%) and dyspnoea in 2 patients (3.9%). The ECG diagnosis was complete heart block in 27 patients (53%), second degree heart block in 19 patients (37.2%) and sick sinus syndrome with bradycardia in 5 patients (9.8%). Pacemaker modes used were ventricular pacing in 29 patients (56.9%) and dual chamber pacing in 22 patients (43.1%). Files have been closed in 20 patients (39.2%) and 31 patients (60.8%) are still being followed up with median follow up of 26 months, median of 5 visits and 282 pacemaker checks done. Complications seen during follow up were 3 lead displacements (5.9%), 3 pacemaker infections (5.9%), 2 pacemaker pocket erosions (3.9%), and 1 pacemaker related death (2%). There were 5 non-pacemaker related deaths (9.8%). Pacemaker data has been maintained for 5 years. We urge other implanting institutions in Nigeria to maintain similar databases and work towards establishment of a national pacemaker registry.

  3. Hyperpolarization-Activated Current, , in Mathematical Models of Rabbit Sinoatrial Node Pacemaker Cells

    Directory of Open Access Journals (Sweden)

    Arie O. Verkerk

    2013-01-01

    Full Text Available A typical feature of sinoatrial (SA node pacemaker cells is the presence of an ionic current that activates upon hyperpolarization. The role of this hyperpolarization-activated current, , which is also known as the “funny current” or “pacemaker current,” in the spontaneous pacemaker activity of SA nodal cells remains a matter of intense debate. Whereas some conclude that plays a fundamental role in the generation of pacemaker activity and its rate control, others conclude that the role of is limited to a modest contribution to rate control. The ongoing debate is often accompanied with arguments from computer simulations, either to support one's personal view or to invalidate that of the antagonist. In the present paper, we review the various mathematical descriptions of that have been used in computer simulations and compare their strikingly different characteristics with our experimental data. We identify caveats and propose a novel model for based on our experimental data.

  4. Psychosocial aspects and mental health in children after permanent pacemaker implantation

    DEFF Research Database (Denmark)

    Andersen, C; Hørder, K; Kristensen, L

    1994-01-01

    The present study was designed to evaluate the psychosocial status and the mental health of children receiving a permanent pacemaker during childhood. Nineteen children under the age of 19 years had a permanent pacemaker implanted. Contact was established to 15 of these patients, 7 girls and 8 boys......, and they were given a child-psychiatric evaluation consisting of a semi-structured and a child-psychiatric interview. The psychological interview used intelligence tests and the Draw-A-Person test as well as the Rorschach test. The patients had had their pacemakers during an average of 6.7 years (range 3......-14). Generally the psychological condition was strained in 7 families, in which psychiatric and social therapy had been necessary. The children's intelligence was within normal ranges, average IQ being 110 (range 80-135). The children had abnormal body image related to the pacemaker. Adults virtually incorporate...

  5. Psychosocial aspects and mental health in children after permanent pacemaker implantation

    DEFF Research Database (Denmark)

    Andersen, C; Hørder, K; Kristensen, L

    1994-01-01

    -14). Generally the psychological condition was strained in 7 families, in which psychiatric and social therapy had been necessary. The children's intelligence was within normal ranges, average IQ being 110 (range 80-135). The children had abnormal body image related to the pacemaker. Adults virtually incorporate......The present study was designed to evaluate the psychosocial status and the mental health of children receiving a permanent pacemaker during childhood. Nineteen children under the age of 19 years had a permanent pacemaker implanted. Contact was established to 15 of these patients, 7 girls and 8 boys......, and they were given a child-psychiatric evaluation consisting of a semi-structured and a child-psychiatric interview. The psychological interview used intelligence tests and the Draw-A-Person test as well as the Rorschach test. The patients had had their pacemakers during an average of 6.7 years (range 3...

  6. Magnetic Resonance Imaging in a Patient with a Dual Chamber Pacemaker

    Directory of Open Access Journals (Sweden)

    Lynne Martina Millar

    2010-01-01

    Full Text Available Having a pacemaker has been seen an absolute contraindication to having an MRI scan. This has become increasingly difficult in clinical practice as insertion of pacemakers and implantable cardiac defibrillators is at an all time high. Here we outline a case where a 71-year-old male patient with a permanent pacemaker needed to have an MRI scan to ascertain the aetiology of his condition and help guide further management. Given this clinical dilemma, an emergency clinical ethics consultation was arranged. As a result the patient underwent an MRI scan safely under controlled conditions with a consultant cardiologist and radiologist present. The results of the MRI scan were then able to tailor further treatment. This case highlights that in certain conditions an MRI can be performed in patients with permanent pacemakers and outlines the role of clinical ethics committees in complex medical decision making.

  7. What Counts as a Flexible Representational Choice? An Evaluation of Students' Representational Choices to Solve Linear Function Problems

    Science.gov (United States)

    Nistal, Ana Acevedo; Van Dooren, Wim; Verschaffel, Lieven

    2012-01-01

    This study evaluated students' representational choices while they solved linear function problems. Eighty-six secondary-school students solved problems under one choice condition, where they chose a table, a formula, or both to solve each problem, and two no-choice conditions, where one of these representations was forced upon them. Two…

  8. Medicare’s Policies and Prospective Payment Rates for Cardiac Pacemaker Surgeries need Review and Revision.

    Science.gov (United States)

    1985-02-26

    pacemaker manufacturers whose sales account for about 80 percent of the pacemaker sales in the United States. The four manufacturers are: -- Cordis ...percentage increase in the hospital market basket (an index designed to measure changes in the prices hospitals pay for goods and services) plus 0.25 percent...For fiscal year 1986, the DRG payment rates cannot be in- creased by more than the estimated change in the hospital market basket plus 0.25 percent

  9. Safety and effectiveness of a 6 French MRI conditional pacemaker lead

    DEFF Research Database (Denmark)

    Nielsen, Jens C; Giudici, Michael; Tolasana Viu, Jose Maria

    2017-01-01

    BACKGROUND: The design of pacemaker leads has continued to evolve; ease of lead handling, improved electrical performance and MRI conditional aspects have become more important, while safety remains critical. The INGEVITY™ family leads was designed to provide MRI conditional aspects, decreased...... diameter, and improved performance of pacemaker leads. The INGEVITY study is an investigational device exemption trial evaluating the acute and chronic safety and effectiveness of these leads. METHODS: Consecutive patients were included in 77 institutions worldwide, where 1657 leads (846 right ventricular...

  10. The neuropeptide PDF acts directly on evening pacemaker neurons to regulate multiple features of circadian behavior.

    Science.gov (United States)

    Lear, Bridget C; Zhang, Luoying; Allada, Ravi

    2009-07-01

    Discrete clusters of circadian clock neurons temporally organize daily behaviors such as sleep and wake. In Drosophila, a network of just 150 neurons drives two peaks of timed activity in the morning and evening. A subset of these neurons expresses the neuropeptide pigment dispersing factor (PDF), which is important for promoting morning behavior as well as maintaining robust free-running rhythmicity in constant conditions. Yet, how PDF acts on downstream circuits to mediate rhythmic behavior is unknown. Using circuit-directed rescue of PDF receptor mutants, we show that PDF targeting of just approximately 30 non-PDF evening circadian neurons is sufficient to drive morning behavior. This function is not accompanied by large changes in core molecular oscillators in light-dark, indicating that PDF RECEPTOR likely regulates the output of these cells under these conditions. We find that PDF also acts on this focused set of non-PDF neurons to regulate both evening activity phase and period length, consistent with modest resetting effects on core oscillators. PDF likely acts on more distributed pacemaker neuron targets, including the PDF neurons themselves, to regulate rhythmic strength. Here we reveal defining features of the circuit-diagram for PDF peptide function in circadian behavior, revealing the direct neuronal targets of PDF as well as its behavioral functions at those sites. These studies define a key direct output circuit sufficient for multiple PDF dependent behaviors.

  11. Modelling metal speciation in the Scheldt Estuary: Combining a flexible-resolution transport model with empirical functions

    Energy Technology Data Exchange (ETDEWEB)

    Elskens, Marc [Vrije Universiteit Brussel, Analytical, Pleinlaan 2, BE-1050 Brussels (Belgium); Gourgue, Olivier [Université catholique de Louvain, Institute of Mechanics, Materials and Civil Engineering (IMMC), 4 Avenue G. Lemaître, bte L4.05.02, BE-1348 Louvain-la-Neuve (Belgium); Université catholique de Louvain, Georges Lemaître Centre for Earth and Climate Research (TECLIM), Place Louis Pasteur 2, bte L4.03.08, BE-1348 Louvain-la-Neuve (Belgium); Baeyens, Willy [Vrije Universiteit Brussel, Analytical, Pleinlaan 2, BE-1050 Brussels (Belgium); Chou, Lei [Université Libre de Bruxelles, Biogéochimie et Modélisation du Système Terre (BGéoSys) —Océanographie Chimique et Géochimie des Eaux, Campus de la Plaine —CP 208, Boulevard du Triomphe, BE-1050 Brussels (Belgium); Deleersnijder, Eric [Université catholique de Louvain, Institute of Mechanics, Materials and Civil Engineering (IMMC), 4 Avenue G. Lemaître, bte L4.05.02, BE-1348 Louvain-la-Neuve (Belgium); Université catholique de Louvain, Earth and Life Institute (ELI), Georges Lemaître Centre for Earth and Climate Research (TECLIM), Place Louis Pasteur 2, bte L4.03.08, BE-1348 Louvain-la-Neuve (Belgium); Leermakers, Martine [Vrije Universiteit Brussel, Analytical, Pleinlaan 2, BE-1050 Brussels (Belgium); and others

    2014-04-01

    Predicting metal concentrations in surface waters is an important step in the understanding and ultimately the assessment of the ecological risk associated with metal contamination. In terms of risk an essential piece of information is the accurate knowledge of the partitioning of the metals between the dissolved and particulate phases, as the former species are generally regarded as the most bioavailable and thus harmful form. As a first step towards the understanding and prediction of metal speciation in the Scheldt Estuary (Belgium, the Netherlands), we carried out a detailed analysis of a historical dataset covering the period 1982–2011. This study reports on the results for two selected metals: Cu and Cd. Data analysis revealed that both the total metal concentration and the metal partitioning coefficient (K{sub d}) could be predicted using relatively simple empirical functions of environmental variables such as salinity and suspended particulate matter concentration (SPM). The validity of these functions has been assessed by their application to salinity and SPM fields simulated by the hydro-environmental model SLIM. The high-resolution total and dissolved metal concentrations reconstructed using this approach, compared surprisingly well with an independent set of validation measurements. These first results from the combined mechanistic-empirical model approach suggest that it may be an interesting tool for risk assessment studies, e.g. to help identify conditions associated with elevated (dissolved) metal concentrations. - Highlights: • Empirical functions were designed for assessing metal speciation in estuarine water. • The empirical functions were implemented in the hydro-environmental model SLIM. • Validation was carried out in the Scheldt Estuary using historical data 1982–2011. • This combined mechanistic-empirical approach is useful for risk assessment.

  12. Irregular excitation patterns in reaction-diffusion systems due to perturbation by secondary pacemakers.

    Science.gov (United States)

    Lenk, Claudia; Einax, Mario; Maass, Philipp

    2013-04-01

    Spatiotemporal excitation patterns in the FitzHugh-Nagumo model are studied, which result from the disturbance of a primary pacemaker by a secondary pacemaker. The primary and secondary pacemakers generate regular waves with frequencies f(pace) and f(pert), respectively. The pacemakers are spatially separated, but waves emanating from them encounter each other via a small bridge. This leads to three different types I-III of irregular excitation patterns in disjunct domains of the f(pace)-f(pert) plane. Types I and II are caused by detachments of waves coming from the two pacemakers at corners of the bridge. Type III irregularities are confined to a boundary region of the system and originate from a partial penetration of the primary waves into a space, where circular wave fronts from the secondary pacemaker prevail. For this type, local frequencies can significantly exceed f(pace) and f(pert). The degree of irregularity found for the three different types is quantified by the entropy of the local frequency distribution and an order parameter for phase coherence.

  13. Involvement of mitochondrial Na+-Ca2+ exchange in intestinal pacemaking activity

    Institute of Scientific and Technical Information of China (English)

    Byung Joo Kim; Jae Yeoul Jun; Insuk So; Ki Whan Kim

    2006-01-01

    AIM: Interstitial cells of Cajal (ICCs) are the pacemaker cells that generate slow waves in the gastrointestinal (GI) tract. We have aimed to investigate the involvement of mitochondrial Na+-Ca2+ exchange in intestinal pacemaking activity in cultured interstitial cells of Cajal.METHODS: Enzymatic digestions were used todissociate ICCs from the small intestine of a mouse. The whole-cell patch-clamp configuration was used to record membrane currents (voltage clamp) and potentials (current clamp) from cultured ICCs.RESULTS: Clonazepam and CGP37157 inhibited the pacemaking activity of ICCs in a dose-dependent manner.Clonazepam from 20 to 60 μmol/L and CGP37157 from 10 to 30 μmol/L effectively inhibited Ca2+ efflux from mitochondria in pacemaking activity of ICCs. The IC50S of clonazepam and CGP37157 were 37.1 and 18.2 μmol/L, respectively. The addition of 20 μmol/L NiCl2 to the internal solution caused a "wax and wane" phenomenon of pacemaking activity of ICCs.CONCLUSION: These results suggest that mitochondrial Na+-Ca2+ exchange has an important role in intestinal pacemaking activity.

  14. Evaluation of Death among the Patients Undergoing Permanent Pacemaker Implantation: A Competing Risks Analysis.

    Science.gov (United States)

    Ghaem, Haleh; Ghorbani, Mohammad; Zare Dorniani, Samira

    2017-06-01

    Permanent artificial pacemaker is one of the important therapies for treatment of cardiac conduction system problems. The present study aimed to determine the association between some predictive variables and all-cause and cause-specific mortality in the patients who had undergone pacemaker implantation. This study was conducted on 1207 patients who had undergone permanent pacemaker implantation in the hospitals affiliated with Shiraz University of Medical Sciences, Iran, from Mar 2002 to Mar 2012. The variables that existed in the patients' medical records included sex, diabetes mellitus, obesity, cerebrovascular accident, cardiomegaly, smoking, hypertension, ischemic heart disease, congenital heart disease, sick sinus syndrome, and atrial fibrillation. Competing risks model was used to assess the association between the predictive variables and cause-specific (i.e., cardiac and vascular) mortality. The patients' mean age was 66.32±17.92 yr (70.62±14.45 yr in the patients with single-chamber pacemakers vs. 61.91±17.69 yr in those with two-chamber pacemakers) (Ppacemaker decreased this risk. Obesity increased the risk of cardiac death, and diabetes mellitus and heart valve disease increased the risk of vascular death. The variables predicting mortality in all-cause model were completely different from those in cause-specific model. Moreover, death in such patients may occur due to reasons other than pacemaker. Therefore, future studies, particularly prospective ones, are recommended to use competing risks models.

  15. Case report: Pacemaker lead perforation of a papillary muscle inducing severe tricuspid regurgitation.

    Science.gov (United States)

    Andreas, Martin; Gremmel, Franz; Habertheuer, Andreas; Rath, Claus; Oeser, Claudia; Khazen, Cesar; Kocher, Alfred

    2015-03-25

    We report a rare but severe pacemaker complication of a pacemaker lead perforating the papillary muscle. This induced severe tricuspid regurgitation and right heart failure. Patients suffering from right heart failure have an increased operative risk of open-heart surgery and therefore represent a clinical challenge due to the lack of clear guidelines. A 70-year-old male patient presented with severe tricuspid regurgitation and a history of decompensated right heart failure. One pacemaker lead was described as 'whipping'. Four years earlier he had received a VVIR pacemaker with a passive lead. This lead failed after three years and a new ventricular lead had been placed. We performed on-pump beating heart surgery after a multidisciplinary decision process. One lead was perforating the posterior papillary muscle, severely impairing valve movement. The tricuspid valve was replaced with a stented bioprosthesis. Epicardial pacemaker wires were placed on the right and left ventricle to enable cardiac resynchronization therapy in the case of postoperative heart failure. However, the patient recovered quickly without left ventricular pacing and could be discharged home 12 days after surgery. This particular case emphasizes the importance of meticulous surgical technique during pacemaker lead implantation and a tight postoperative follow-up including echocardiography in complicated cases. The management of patients with an indication for lead removal having developed secondary severe tricuspid valve dysfunction inducing ventricular impairment represents a clinical challenge and should be approached by a multidisciplinary team.

  16. Pacemaker rate and depolarization block in nigral dopamine neurons: a somatic sodium channel balancing act

    Science.gov (United States)

    Tucker, Kristal R.; Huertas, Marco A.; Horn, John P.; Canavier, Carmen C.; Levitan, Edwin S.

    2012-01-01

    Midbrain dopamine (DA) neurons are slow intrinsic pacemakers that undergo depolarization (DP) block upon moderate stimulation. Understanding DP block is important because it has been correlated with the clinical efficacy of chronic antipsychotic drug treatment. Here we describe how voltage-gated sodium (NaV) channels regulate DP block and pacemaker activity in DA neurons of the substantia nigra using rat brain slices. The distribution, density and gating of NaV currents were manipulated by blocking native channels with tetrodotoxin and by creating virtual channels and anti-channels with dynamic clamp. Although action potentials initiate in the axon initial segment (AIS) and NaV channels are distributed in multiple dendrites, selective reduction of NaV channel activity in the soma was sufficient to decrease pacemaker frequency and increase susceptibility to DP block. Conversely, increasing somatic NaV current density raised pacemaker frequency and lowered susceptibility to DP block. Finally, when NaV currents were restricted to the soma, pacemaker activity occurred at abnormally high rates due to excessive local subthreshold NaV current. Together with computational simulations, these data show that both the slow pacemaker rate and the sensitivity to DP block that characterizes DA neurons result from the low density of somatic NaV channels. More generally, we conclude that the somatodendritic distribution of NaV channels is a major determinant of repetitive spiking frequency. PMID:23077037

  17. Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

    Science.gov (United States)

    Rimmbach, Christian; Jung, Julia J.; David, Robert

    2015-01-01

    Treatment of the “sick sinus syndrome” is based on artificial pacemakers. These bear hazards such as battery failure and infections. Moreover, they lack hormone responsiveness and the overall procedure is cost-intensive. “Biological pacemakers” generated from PSCs may become an alternative, yet the typical content of pacemaker cells in Embryoid Bodies (EBs) is extremely low. The described protocol combines “forward programming” of murine PSCs via the sinus node inducer TBX3 with Myh6-promoter based antibiotic selection. This yields cardiomyocyte aggregates consistent of >80% physiologically functional pacemaker cells. These “induced-sinoatrial-bodies” (“iSABs”) are spontaneously contracting at yet unreached frequencies (400-500 bpm) corresponding to nodal cells isolated from mouse hearts and are able to pace murine myocardium ex vivo. Using the described protocol highly pure sinus nodal single cells can be generated which e.g. can be used for in vitro drug testing. Furthermore, the iSABs generated according to this protocol may become a crucial step towards heart tissue engineering. PMID:25742394

  18. Cross-sectional study of rate-adaptive pacemaker in Shanghai area%频率应答起搏器在上海地区的应用情况

    Institute of Scientific and Technical Information of China (English)

    李骁; 毛家亮; 刘志刚; 李京波; 蒋金发; 李莹; 乔增勇; 宿燕岗; 葛均波

    2016-01-01

    Objective To investigate the use of rate-adaptive pacemaker in Shanghai area and provide a preliminary overview of application of rate-adaptive function in clinical practice. Methods We selected 16 hospitals covering most districts of Shanghai and collected data in the patient demographics,types of arrhythmi-a,types of pacemaker and status of rate-adaptive function of pacemakers that were implanted from February 2013 to February 2014. In addition,we analyzed clinicians’ perspective in rate-adaptive function by means of questionnaire. Results The proportion of rate-adaptive pacemaker was 74. 86 ( predominantly DDDR) . How-ever,only 36. 63% of these pacemaker had rate-adaptive function turned on. Most were kept turned off on pur-pose. The main reason for rate-adaptive function turned off was that patients had been used to low heart rate be-fore pacemaker implantation,leading to 50. 97% patients had it turned off during follow up. Clinicians paid little attention to chronotropic incompetence or age before rate-adaptive pacemaker implantation. Conclusion The proportion of rate-adaptive pacemaker is high. However,the proportion of these pacemakers that had rate-adap-tive function turned on is low. More attention should be paid to standardize default setting and follow up strategy of rate-adaptive pacemakers.%目的:调查上海地区频率应答起搏器的使用情况,为国内该领域提供较为客观的临床现状数据。方法选取覆盖上海多数区县的16家医院,对2013年2月至2014年2月已植入频率应答起搏器患者的人口学情况、心律失常原因、起搏器类型和开启及开启后关闭频率应答功能的情况进行回顾性研究。另外,问卷调查每家医院2~3名植入医生对频率应答起搏器使用情况等的看法。结果①频率应答起搏器植入比例高达74.86%(主要为DDDR),但频率应答功能开启比例不高(平均36.63%),主观有意识不开启R功能的主要原因;②开启

  19. Size, flexibility, and scattering functions of semiflexible polyelectrolytes with excluded volume effects: Monte Carlo simulations and neutron scattering experiments

    DEFF Research Database (Denmark)

    Cannavacciuolo, L.; Sommer, C.; Pedersen, J.S.;

    2000-01-01

    We present a systematic Monte Carlo study of the scattering function S(q) of semiflexible polyelectrolytes at infinite dilution, in solutions with different concentrations of added salt. In the spirit of a theoretical description of polyelectrolytes in terms of the equivalent parameters, namely...... outlined in the Odijk-Skolnick-Fixman theory, in which the behavior of charged polymers is described only in terms of increasing local rigidity and excluded volume effects. Moreover, the Monte Carlo data are found to be in very good agreement with experimental scattering measurements with equilibrium...

  20. Vicinal 1H-1H NMR coupling constants from density functional theory as reliable tools for stereochemical analysis of highly flexible multichiral center molecules.

    Science.gov (United States)

    López-Vallejo, Fabian; Fragoso-Serrano, Mabel; Suárez-Ortiz, Gloria Alejandra; Hernández-Rojas, Adriana C; Cerda-García-Rojas, Carlos M; Pereda-Miranda, Rogelio

    2011-08-05

    A protocol for stereochemical analysis, based on the systematic comparison between theoretical and experimental vicinal (1)H-(1)H NMR coupling constants, was developed and applied to a series of flexible compounds (1-8) derived from the 6-heptenyl-5,6-dihydro-2H-pyran-2-one framework. The method included a broad conformational search, followed by geometry optimization at the DFT B3LYP/DGDZVP level, calculation of the vibrational frequencies, thermochemical parameters, magnetic shielding tensors, and the total NMR spin-spin coupling constants. Three scaling factors, depending on the carbon atom hybridizations, were found for the (1)H-C-C-(1)H vicinal coupling constants: f((sp3)-(sp3)) = 0.910, f((sp3)-(sp2)) = 0.929, and f((sp2)-(sp2))= 0.977. A remarkable correlation between the theoretical (J(pre)) and experimental (1)H-(1)H NMR (J(exp)) coupling constants for spicigerolide (1), a cytotoxic natural product, and some of its synthetic stereoisomers (2-4) demonstrated the predictive value of this approach for the stereochemical assignment of highly flexible compounds containing multiple chiral centers. The stereochemistry of two natural 6-heptenyl-5,6-dihydro-2H-pyran-2-ones (14 and 15) containing diverse functional groups in the heptenyl side chain was also analyzed by application of this combined theoretical and experimental approach, confirming its reliability. Additionally, a geometrical analysis for the conformations of 1-8 revealed that weak hydrogen bonds substantially guide the conformational behavior of the tetraacyloxy-6-heptenyl-2H-pyran-2-ones.

  1. Dosimetric perturbations due to an implanted cardiac pacemaker in MammoSite{sup Registered-Sign} treatment

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Wonmo; Kim, Siyong; Kim, Jung-in; Lee, Jae-gi; Shin, Young-Joo; Jung, Jae-Yong; Ye, Sung-Joon [Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799, South Korea and Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 110-744 (Korea, Republic of); Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida 32224 (United States); Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799, South Korea and Department of Radiation Oncology, Kangbuk Samsung Medical Center, Seoul 110-746 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 110-744, South Korea and Department of Biomedical Radiation Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Department of Radiation Oncology, Sanggye Paik Hospital, Inje University, Seoul 139-707 (Korea, Republic of); Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 110-744 (Korea, Republic of); Department of Biomedical Radiation Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Department of Radiation Oncology, Seoul National University, Seoul 110-799 (Korea, Republic of) and Advanced Institutes of Convergence Technology, Seoul National University, Suwon 443-270 (Korea, Republic of)

    2012-10-15

    Purpose: To investigate dose perturbations for pacemaker-implanted patients in partial breast irradiation using high dose rate (HDR) balloon brachytherapy. Methods: Monte Carlo (MC) simulations were performed to calculate dose distributions involving a pacemaker in Ir-192 HDR balloon brachytherapy. Dose perturbations by varying balloon-to-pacemaker distances (BPD = 50 or 100 mm) and concentrations of iodine contrast medium (2.5%, 5.0%, 7.5%, and 10.0% by volume) in the balloon were investigated for separate parts of the pacemaker (i.e., battery and substrate). Relative measurements using an ion-chamber were also performed to confirm MC results. Results: The MC and measured results in homogeneous media without a pacemaker agreed with published data within 2% from the balloon surface to 100 mm BPD. Further their dose distributions with a pacemaker were in a comparable agreement. The MC results showed that doses over the battery were increased by a factor of 3, compared to doses without a pacemaker. However, there was no significant dose perturbation in the middle of substrate but up to 70% dose increase in the substrate interface with the titanium capsule. The attenuation by iodine contrast medium lessened doses delivered to the pacemaker by up to 9%. Conclusions: Due to inhomogeneity of pacemaker and contrast medium as well as low-energy photons in Ir-192 HDR balloon brachytherapy, the actual dose received in a pacemaker is different from the homogeneous medium-based dose and the external beam-based dose. Therefore, the dose perturbations should be considered for pacemaker-implanted patients when evaluating a safe clinical distance between the balloon and pacemaker.

  2. Use of an active fixation lead and a subpectoral pacemaker pocket may not avoid Twiddler′s syndrome

    Directory of Open Access Journals (Sweden)

    Floris E A Udink ten Cate

    2012-01-01

    Full Text Available Manipulation of a pacemaker with consequent malfunction of the device has been called Twiddler′s syndrome. Use of active-fixation leads and subpectoral pacemaker pockets has been considered to help in avoiding this problem. We describe a child in whom twiddling was not prevented despite implantation of a lumenless atrial lead and insertion of the pacemaker generator in a subpectoral pocket.

  3. Simple hand-held metal detectors are an effective means of detecting cardiac pacemakers in the deceased prior to cremation.

    Science.gov (United States)

    Stone, Jason Lyle; Williams, John; Fearn, Lesley

    2010-05-01

    The hazard of undetected cardiac pacemakers exploding in crematoria is well described. This short report describes the use of an affordable hand-held metal detector to detect cardiac pacemakers. Over the course of a year, the metal detector located 100% of cardiac pacemakers in a district general hospital mortuary. A simple model using pigskin and fat is also used to demonstrate the effectiveness in vitro. Commercially purchased hand-held metal detectors should be used in all mortuaries responsible for detection and removal of cardiac pacemakers prior to cremation.

  4. Risk of pacemaker implantation subsequent to radiotherapy for early-stage breast cancer in Denmark, 1982-2005

    DEFF Research Database (Denmark)

    Rehammar, Jens Christian; Videbaek, L.; Brock Johansen, J.

    2015-01-01

    -stage breast cancer in Denmark from 1982 to 2005. By record linkage to the Danish Pacemaker and ICD Registry information was retrieved on pacemaker implants subsequent to radiotherapy. Rate ratios (RR) of pacemaker implantation for left versus right sided breast cancer were calculated. Results: Among 18......,308 women treated with radiotherapy for early-stage breast cancer, 179 women had a pacemaker implanted subsequent to radiotherapy, 90 in 9,315 left sided and 89 in 8,993 right sided breast cancers. The unadjusted RR was 1.02 (0.76-1.36 95% CI, p=0.91) and the RR adjusted for year, age and time since...

  5. Trends in permanent pacemaker implantation in the United States from 1993 to 2009: increasing complexity of patients and procedures.

    Science.gov (United States)

    Greenspon, Arnold J; Patel, Jasmine D; Lau, Edmund; Ochoa, Jorge A; Frisch, Daniel R; Ho, Reginald T; Pavri, Behzad B; Kurtz, Steven M

    2012-10-16

    This study sought to define contemporary trends in permanent pacemaker use by analyzing a large national database. The Medicare National Coverage Determination for permanent pacemaker, which emphasized single-chamber pacing, has not changed significantly since 1985. We sought to define contemporary trends in permanent pacemaker use by analyzing a large national database. We queried the Nationwide Inpatient Sample to identify permanent pacemaker implants between 1993 and 2009 using the International Classification of Diseases-Ninth Revision-Clinical Modification procedure codes for dual-chamber (DDD), single-ventricular (VVI), single-atrial (AAI), or biventricular (BiV) devices. Annual permanent pacemaker implantation rates and patient demographics were analyzed. Between 1993 and 2009, 2.9 million patients received permanent pacemakers in the United States. Overall use increased by 55.6%. By 2009, DDD use increased from 62% to 82% (p pacemaker use fell from 36% to 14% (p = 0.01). Use of DDD devices was higher in urban, nonteaching hospitals (79%) compared with urban teaching hospitals (76%) and rural hospitals (72%). Patients with private insurance (83%) more commonly received DDD devices than Medicaid (79%) or Medicare (75%) recipients (p pacemakers in the United States. Although DDD device use is increasing, whereas single-chamber ventricular pacemaker use is decreasing. Patients are becoming older and have more medical comorbidities. These trends have important health care policy implications. Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  6. Phentolamine inhibits the pacemaker activity of mouse interstitial cells of Cajal by activating ATP-sensitive K+ channels.

    Science.gov (United States)

    Ahn, Seung Whan; Kim, Sang Hun; Kim, Jin Ho; Choi, Seok; Yeum, Cheol Ho; Wie, Hee Wook; Sun, Jae Myeong; So, Insuk; Jun, Jae Yeoul

    2010-03-01

    The aim of this study was to clarify if phentolamine has proven effects on the pacemaker activities of interstitial cells of Cajal (ICC) from the mouse small intestine involving the ATPsensitive K(+) channels and adrenergic receptor. The actions of phentolamine on pacemaker activities were investigated using whole-cell patch-clamp technique and intracellular Ca(2+) analysis at 30 degrees C in cultured mouse intestinal ICC. ICC generated spontaneous pacemaker currents at a holding potential of -70 mV. Treatment with phentolamine reduced the frequency and amplitude of the pacemaker currents and increased the resting outward currents. Moreover, under current clamping (I = 0), phentolamine hyperpolarized the ICC membrane and decreased the amplitude of the pacemaker potentials. We also observed that phentolamine inhibited spontaneous [Ca(2+)](i) oscillations in ICC. The alpha-adrenergic drugs prazosin, yohimbine, methoxamine, and clonidine had no effect on ICC intestinal pacemaker activity and did not block phentolamine-induced effects. Phentolamine-induced effects on the pacemaker currents and the pacemaker potentials were significantly inhibited by ATP sensitive K(+) channel blocker glibenclamide, but not by TEA, apamin, or 4-aminopyridine. In addition, the NO synthase inhibitor, L-NAME and the guanylate cyclase inhibitor, ODQ were incapable of blocking the phentolamine-induced effects. These results demonstrate that phentolamine regulates the pacemaker activity of ICC via ATP-sensitive K(+) channel activation. Phentolamine could act through an adrenergic receptor- and also through NO-independent mechanism that involves intracellular Ca(2+) signaling.

  7. Propagation of pacemaker activity in the guinea-pig antrum.

    Science.gov (United States)

    Hennig, G W; Hirst, G D S; Park, K J; Smith, C B; Sanders, K M; Ward, S M; Smith, T K

    2004-04-15

    Cyclical periods of depolarization (slow waves) underlie peristaltic contractions involved in mixing and emptying of contents in the gastric antrum. Slow waves originate from a myenteric network of interstitial cells of Cajal (ICC-MY). In this study we have visualized the sequence and propagation of Ca(2+) transients associated with pacemaker potentials in the ICC network and longitudinal (LM) and circular muscle (CM) layers of the isolated guinea-pig gastric antrum. Gastric antrum was dissected to reveal the ICC-MY network, loaded with Fluo-4 AM and activity was monitored at 37 degrees C. Ca(2+) waves propagated throughout the ICC-MY network at an average velocity of 3.24 +/- 0.12 mm s(-1) at a frequency of 4.87 +/- 0.16 cycles min(-1) (n= 4). The propagation of the Ca(2+) wave often appeared 'step-like', with separate regions of the network being activated after variable delays. The direction of propagation was highly variable (Delta angle of propagation 44.3 +/- 10.9 deg per cycle) and was not confined to the axes of the longitudinal or circular muscle. Ca(2+) waves appeared to spread out radially from the site of initiation. The initiating Ca(2+) wave in ICC-MY was correlated to secondary Ca(2+) waves in intramuscular interstitial cells of Cajal, ICC-IM, and smooth muscle cells, and the local distortion (contraction) in a field of view. TTX (1 microm) had little effect on slow wave or pacemaker potential activity, but 2-APB (50 microm) blocked all Ca(2+) waves, indicating a pivotal role for intracellular Ca(2+) stores. Nicardipine (2 microm) eliminated the Ca(2+) transient generated by smooth muscle, but did not affect the fast upstroke associated with ICC-MY. These results indicate that slow waves follow a sequence of activation, beginning with the ICC-MY and ICC-IM network, followed later by a sustained Ca(2+) transient in the muscle layers that is responsible for contraction.

  8. The flexible nature of exchange, correlation, and Hartree physics: Resolving ``delocalization'' errors in a ``correlation free'' density functional

    Science.gov (United States)

    Gould, Tim; Dobson, John F.

    2013-01-01

    By exploiting freedoms in the definitions of "correlation," "exchange," and "Hartree" physics in ensemble systems, we better generalise the notion of "exact exchange" (EXX) to systems with fractional occupations of the frontier orbitals, arising in the dissociation limit of some molecules. We introduce the linear EXX ("LEXX") theory whose pair distribution and energy are explicitly piecewise linear in the occupations f^{σ }i. We provide explicit expressions for these functions for frontier s and p shells. Used in an optimised effective potential (OEP) approach the LEXX yields energies bounded by the piecewise linear "ensemble EXX" (EEXX) energy and standard fractional optimised EXX energy: EEEXX ⩽ ELEXX ⩽ EEXX. Analysis of the LEXX explains the success of standard OEP methods for diatoms at large spacing, and why they can fail when both spins are allowed to be non-integer so that "ghost" Hartree interactions appear between opposite spin electrons in the usual formula. The energy ELEXX contains a cancellation term for the spin ghost case. It is evaluated for H, Li, and Na fractional ions with clear derivative discontinuities for all cases. The p-shell form reproduces accurate correlation-free energies of B-F and Al-Cl. We further test LEXX plus correlation energy calculations on fractional ions of C and F and again we find both derivative discontinuities and good agreement with exact results.

  9. The flexible nature of exchange, correlation, and Hartree physics: resolving "delocalization" errors in a "correlation free" density functional.

    Science.gov (United States)

    Gould, Tim; Dobson, John F

    2013-01-07

    By exploiting freedoms in the definitions of "correlation," "exchange," and "Hartree" physics in ensemble systems, we better generalise the notion of "exact exchange" (EXX) to systems with fractional occupations of the frontier orbitals, arising in the dissociation limit of some molecules. We introduce the linear EXX ("LEXX") theory whose pair distribution and energy are explicitly piecewise linear in the occupations f(i)(σ). We provide explicit expressions for these functions for frontier s and p shells. Used in an optimised effective potential (OEP) approach the LEXX yields energies bounded by the piecewise linear "ensemble EXX" (EEXX) energy and standard fractional optimised EXX energy: E(EEXX) ≤ E(LEXX) ≤ E(EXX). Analysis of the LEXX explains the success of standard OEP methods for diatoms at large spacing, and why they can fail when both spins are allowed to be non-integer so that "ghost" Hartree interactions appear between opposite spin electrons in the usual formula. The energy E(LEXX) contains a cancellation term for the spin ghost case. It is evaluated for H, Li, and Na fractional ions with clear derivative discontinuities for all cases. The p-shell form reproduces accurate correlation-free energies of B-F and Al-Cl. We further test LEXX plus correlation energy calculations on fractional ions of C and F and again we find both derivative discontinuities and good agreement with exact results.

  10. Enhancement of Spontaneous Activity by HCN4 Overexpression in Mouse Embryonic Stem Cell-Derived Cardiomyocytes - A Possible Biological Pacemaker.

    Directory of Open Access Journals (Sweden)

    Yukihiro Saito

    Full Text Available Establishment of a biological pacemaker is expected to solve the persisting problems of a mechanical pacemaker including the problems of battery life and electromagnetic interference. Enhancement of the funny current (If flowing through hyperpolarization-activated cyclic nucleotide-gated (HCN channels and attenuation of the inward rectifier K+ current (IK1 flowing through inward rectifier potassium (Kir channels are essential for generation of a biological pacemaker. Therefore, we generated HCN4-overexpressing mouse embryonic stem cells (mESCs and induced cardiomyocytes that originally show poor IK1 currents, and we investigated whether the HCN4-overexpressing mESC-derived cardiomyocytes (mESC-CMs function as a biological pacemaker in vitro.The rabbit Hcn4 gene was transfected into mESCs, and stable clones were selected. mESC-CMs were generated via embryoid bodies and purified under serum/glucose-free and lactate-supplemented conditions. Approximately 90% of the purified cells were troponin I-positive by immunostaining. In mESC-CMs, expression level of the Kcnj2 gene encoding Kir2.1, which is essential for generation of IK1 currents that are responsible for stabilizing the resting membrane potential, was lower than that in an adult mouse ventricle. HCN4-overexpressing mESC-CMs expressed about a 3-times higher level of the Hcn4 gene than did non-overexpressing mESC-CMs. Expression of the Cacna1h gene, which encodes T-type calcium channel and generates diastolic depolarization in the sinoatrial node, was also confirmed. Additionally, genes required for impulse conduction including Connexin40, Connexin43, and Connexin45 genes, which encode connexins forming gap junctions, and the Scn5a gene, which encodes sodium channels, are expressed in the cells. HCN4-overexpressing mESC-CMs showed significantly larger If currents and more rapid spontaneous beating than did non-overexpressing mESC-CMs. The beating rate of HCN4-overexpressing mESC-CMs responded

  11. [Clinical application of one-stage operation of epicardial permanent pacemaker implantation and cardiac surgery].

    Science.gov (United States)

    Ren, C L; Jiang, S L; Xiao, C S; Wang, R; Gao, C Q

    2017-04-25

    Objective: To summarize the results and clinical application experience of one-stage operation of epicardial permanent pacemaker implantation and cardiac surgery. Methods: From November 2014 to July 2016, 15 patients (9 males and 6 females) with ages ranging from 50 to 73 (63.5±6.2) years requiring cardiac surgery with bradycardia underwent one-stage operation of epicardial permanent pacemaker implantation and cardiac surgery. All operations were performed under general anesthesia with chest median incision approach. Among them, single chamber pacemaker (n=10) and dual chamber pacemaker (n=5) permanent epicardial pacing leads were implanted. Simultaneous procedures included valve replacement in 7 cases, valve replacement combined with atrial fibrillation ablation in 3 cases, coronary artery bypass grafting in 2 cases, aortic root replacement in 2 cases, and valve replacement combined with coronary artery bypass surgery in 1 case. Their parameters of pacemaker including sensitivity, pacing threshold, pacing impedance were measured during surgery and closely followed up at 1 week and 3, 6 months after surgery. Results: All 15 patients with epicardial permanent pacemaker implantation in the same period of cardiac surgery were successfully cured and discharged, without any surgical complications. A total of 20 epicardial electrodes were implanted for them including 5 right atrial electrodes and 15 right ventricular electrodes. The postoperative follow-up period ranged from 3 to 22 months. No electrode fracture and surgical wound infection occurred in those patients, and their impedance, sensing and stimulation thresholds were all in normal ranges during follow-up. Conclusions: For patients with bradycardia who required cardiac surgery, one-stage operation of epicardial permanent pacemaker implantation and cardiac surgery is safe and effective, and the results in the short-term and medium-term are satisfactory, avoiding the risk of staged surgery.

  12. Placement Of Cardiac PacemaKEr Trial (POCKET – rationale and design: a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Peter Magnusson

    2017-04-01

    Full Text Available Background: A pacemaker system consists of one or two leads connected to a device that is implanted into a pocket formed just below the collarbone. This pocket is typically subcutaneous, that is, located just above the pectoral fascia. Even though the size of pacemakers has decreased markedly, complications due to superficial implants do occur. An alternative technique would be intramuscular placement of the pacemaker device, but there are no randomized controlled trials (RCTs to support this approach, which is the rationale for the Placement Of Cardiac PacemaKEr Trial (POCKET. The aim is to study if intramuscular is superior to subcutaneous placement of a pacemaker pocket. Methods: In October 2016, we started to enroll 200 consecutive patients with an indication for bradycardia pacemaker implantation. Patients are randomized to random block sizes, stratified by age group (cut-off: 65 years and sex, and then randomized to either subcutaneous or intramuscular implant. A concealed allocation procedure is employed, using sequentially numbered, sealed envelopes. Pocket site is blinded to the patient and in all subsequent care. The primary endpoint is patient overall satisfaction with the pocket location at 24 months as measured using a visual analog scale (VAS 0-10. Secondary endpoints are: complications, patient-reported satisfaction at 1, 12, and 24 months (overall satisfaction, pain, discomfort, degree of unsightly appearance, movement problems, and sleep problems due to device. Conclusions: POCKET is a prospective interventional RCT designed to evaluate if intramuscular is superior to subcutaneous placement of a bradycardia pacemaker during a two-year follow-up.

  13. Pacemaker-Mediated Tachycardia: Manufacturer Specifics and Spectrum of Cases.

    Science.gov (United States)

    Monteil, Benjamin; Ploux, Sylvain; Eschalier, Romain; Ritter, Philippe; Haissaguerre, Michel; Koneru, Jayanthi N; Ellenbogen, Kenneth A; Bordachar, Pierre

    2015-12-01

    Pacemaker-mediated tachycardia (PMT) is the term used to describe a repetitive sequence of sensed retrograde P waves followed by ventricular pacing at or below the maximum tracking rate. The following events can promote atrioventricular (AV) dissociation, retrograde conduction, and the onset of PMT: ventricular or atrial extrasystole, an excessively long programmed AV delay, external interference or myopotentials sensed by the atrial channel, atrial sensing or pacing failure, the absence of postventricular atrial refractory period extension after removal of a magnet, and VDD pacing at a higher rate than sinus rate. In contemporary devices, each manufacturer has a proprietary algorithm to detect and terminate PMT. Because of the increase in the number and complexity of the pacing algorithms and because of manufacturer-driven differences, a basic understanding of these new algorithms is important for patient care. We review here the main elements of the physiopathology of this type of tachycardia, describe the specific characteristics of the different manufacturers, and present representative clinical cases.

  14. Management of radiation therapy patients with cardiac defibrillator or pacemaker.

    Science.gov (United States)

    Salerno, Francesca; Gomellini, Sara; Caruso, Cristina; Barbara, Raffaele; Musio, Daniela; Coppi, Tamara; Cardinale, Mario; Tombolini, Vincenzo; de Paula, Ugo

    2016-06-01

    The increasing growth of population with cardiac implantable electronic devices (CIEDs) such as Pacemaker (PM) and Implantable Cardiac Defibrillators (ICD), requires particular attention in management of patients needing radiation treatment. This paper updates and summarizes some recommendations from different international guidelines. Ionizing radiation and/or electromagnetic interferences could cause device failure. Current approaches to treatment in patients who have these devices vary among radiation oncology centres. We refer to the German Society of Radiation Oncology and Cardiology guidelines (ed. 2015); to the Society of Cardiology Australia and New Zealand Statement (ed. 2015); to the guidelines in force in the Netherlands (ed. 2012) and to the Italian Association of Radiation Oncology recommendations (ed. 2013) as reported in the guidelines for the treatment of breast cancer in patients with CIED. Although there is not a clear cut-off point, risk of device failure increases with increasing doses. Cumulative dose and pacing dependency have been combined to categorize patients into low-, medium- and high-risk groups. Measures to secure patient safety are described for each category. The use of energy ≤6MV is preferable and it's strongly recommended not to exceed a total dose of 2 Gy to the PM and 1 Gy for ICD. Given the dangers of device malfunction, radiation oncology departments should adopt all the measures designed to minimize the risk to patients. For this reason, a close collaboration between cardiologist, radiotherapist and physicist is necessary.

  15. Characterization of piezoelectric device for implanted pacemaker energy harvesting

    Science.gov (United States)

    Jay, Sunny; Caballero, Manuel; Quinn, William; Barrett, John; Hill, Martin

    2016-10-01

    Novel implanted cardiac pacemakers that are powered by energy harvesters driven by the cardiac motion and have a 40 year lifetime are currently under development. To satisfy space constraints and energy requirements of the device, silicon-based MEMS energy harvesters are being developed in the EU project (MANpower1). Such MEMS harvesters for vibration frequencies below 50 Hz have not been widely reported. In this paper, an analytical model and a 3D finite element model (FEM) to predict displacement and open circuit voltage, validated through experimental analysis using an off-the-shelf low frequency energy harvester, are presented. The harvester was excited through constant amplitude sinusoidal base displacement over a range of 20 to 70 Hz passing through its first mode natural frequency at 47 Hz. At resonance both models predict displacements with an error of less than 2% when compared to the experimental result. Comparing the two models, the application of the experimentally measured damping ratio differs for accurate displacement prediction and the differences in symmetry in the measured and modelled displacement and voltage data around the resonance frequency indicate the two piezoelectric voltage models use different fundamental equations.

  16. Flexible Electronics Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Flexible Electronics Research Facility designs, synthesizes, tests, and fabricates materials and devices compatible with flexible substrates for Army information...

  17. Brief report: cognitive flexibility and focused attention in children and adolescents with Asperger syndrome or high-functioning autism as measured on the computerized version of the Wisconsin Card Sorting Test

    DEFF Research Database (Denmark)

    Kaland, Nils; Smith, Lars; Mortensen, Erik Lykke

    2008-01-01

    The aim of the present study was to assess mental flexibility and set maintenance of a group of individuals with Asperger syndrome (AS) or high-functioning autism (HFA) (N = 13; mean age 16,4), as compared with a matched group of typically developing children and adolescents (N = 13; mean age 15...

  18. Absence epilepsy and sinus dysrhythmia in mice lacking the pacemaker channel HCN2

    Science.gov (United States)

    Ludwig, Andreas; Budde, Thomas; Stieber, Juliane; Moosmang, Sven; Wahl, Christian; Holthoff, Knut; Langebartels, Anke; Wotjak, Carsten; Munsch, Thomas; Zong, Xiangang; Feil, Susanne; Feil, Robert; Lancel, Marike; Chien, Kenneth R.; Konnerth, Arthur; Pape, Hans-Christian; Biel, Martin; Hofmann, Franz

    2003-01-01

    Hyperpolarization-activated cation (HCN) channels are believed to be involved in the generation of cardiac pacemaker depolarizations as well as in the control of neuronal excitability and plasticity. The contributions of the four individual HCN channel isoforms (HCN1–4) to these diverse functions are not known. Here we show that HCN2-deficient mice exhibit spontaneous absence seizures. The thalamocortical relay neurons of these mice displayed a near complete loss of the HCN current, resulting in a pronounced hyperpolarizing shift of the resting membrane potential, an altered response to depolarizing inputs and an increased susceptibility for oscillations. HCN2-null mice also displayed cardiac sinus dysrhythmia, a reduction of the sinoatrial HCN current and a shift of the maximum diastolic potential to hyperpolarized values. Mice with cardiomyocyte- specific deletion of HCN2 displayed the same dysrhythmia as mice lacking HCN2 globally, indicating that the dysrhythmia is indeed caused by sinoatrial dysfunction. Our results define the physiological role of the HCN2 subunit as a major determinant of membrane resting potential that is required for regular cardiac and neuronal rhythmicity. PMID:12514127

  19. Pacemaker System Malfunction Resulting from External Electrical Cardioversion: A Case Report

    Directory of Open Access Journals (Sweden)

    Taku Nishida, MD

    2009-01-01

    Full Text Available In May 2005 a 68-year-old woman received a VDD pacemaker implantation in the right pectoral region at our hospital for the treatment of complete atrioventricular block. In July 2008, she was diagnosed with dilated cardiomyopathy based on histological testing. In November 2008, she developed syncope due to ventricular tachycardia while at another hospital. She underwent external electrical cardioversion with an anterior-lateral paddle position using a single shock of 100 J. This shock led to severe bradycardia resulting in a transfer to our hospital. The physician who provided the shock could not have been aware that the patient had an implanted pacemaker. The skin above the pulse generator was burned. The electrocardiogram showed no pacing spikes or ventricular escape rhythm. Investigation of the pacemaker 3 hours after cardioversion revealed reprogramming of the device and a marked rise in the lead impedance (>3,000 ohm. Removal of the generator and implantation of a biventricular cardioverter defibrillator were required. The emergency situation, the small size of the generator, the small incision made using the buried suture method, and the patient's obesity all probably contributed to the physician's not noticing the implanted pacemaker. It is important to increase awareness of the severe consequences that may follow if the physician administering external defibrillation does not know about the patient's implanted pacemaker.

  20. Differences in atrial septal activation with an intrasinoatrial nodal pacemaker and epicardial sinoatrial nodal pacing.

    Science.gov (United States)

    Goldberg, J M

    1979-01-01

    Changes in Intra-SA nodal pacemaker localization were produced through stimulation of the decentralized cervical vagi and stellate ganglia in the anesthetized dog. Shifts in pacemaker to the rostral, middle, or caudal regions of the SA node produced a change in the timing as well as a change in the sequence of activation of recording sites overlying the AV node. Epicardial pacing with a plaque electrode from either the rostral, middle, or caudal regions of the SA node produced the same activation sequence of the AV nodal electrodes irrespective of the epicardial SA nodal pacing site. The inability of epicardial SA nodal pacing to precisely reproduce the activation pattern of the atrial septum overlying the AV node observed with a natural SA nodal pacemaker can be explained by the geographic relationship of the pacemaker cells within the node to the preferential internodal pathways and the area of atrial tissue stimulated by pacing. Pacing activates a large mass of tissue, whereas an intrinsic pacemaker probably acts as a more localized focus. The inability of pacing to reproduce the activation pattern seen with spontaneous rhythm may be a determinant in the varied P wave morphology seen with coronary sinus or AV nodal junctional rhythms, as compared with more consistent morphology seen with pacing.

  1. Permanent transvenous pacemaker implantation in a patient with Cor triatriatum dextrum

    Institute of Scientific and Technical Information of China (English)

    Kun; Xiang; George; V; Moukarbel; Blair; Grubb

    2015-01-01

    Cor triatriatum dextrum is an extremely rare congenital heart abnormality in which the right atrium is separatedinto two chambers by a persistent fibrous membrane. A transvenous approach to place a dual-chamber pacemaker in such patients is technically challenging. We report the first case of a transvenous permanent pacemaker placement in a patient with cor triatriatum dextrum. An 87-year-old woman was diagnosed with paroxysmal atrial fibrillation. She was accidentally found to have cor triatriatum dextrum during the transesophageal echocardiography(TEE) prior to cardioversion. Later during her hospital stay, it was indicated to place a permanant pacemaker due to high grade atrioventricular block. After thorough reviewing TEE imagings, a transvenous catheter-based approach was decided feasible. Patient successfully received a dual chamber pacemaker through left subclavian venous approach. Furthermore in our case, using specially designed pacemaker leads and cautious intra-procedural maneuvering under fluoroscopic guidance ensured procedural success. In summary, a thorough pre-operative evaluation with transesophageal echocardiography is critical for the planning and eventual success of the transvenous placement of rightsided leads.

  2. Reexposure to nicotine during withdrawal increases the pacemaking activity of cholinergic habenular neurons

    Science.gov (United States)

    Görlich, Andreas; Antolin-Fontes, Beatriz; Ables, Jessica L.; Frahm, Silke; Ślimak, Marta A.; Dougherty, Joseph D.; Ibañez-Tallon, Inés

    2013-01-01

    The discovery of genetic variants in the cholinergic receptor nicotinic CHRNA5-CHRNA3-CHRNB4 gene cluster associated with heavy smoking and higher relapse risk has led to the identification of the midbrain habenula–interpeduncular axis as a critical relay circuit in the control of nicotine dependence. Although clear roles for α3, β4, and α5 receptors in nicotine aversion and withdrawal have been established, the cellular and molecular mechanisms that participate in signaling nicotine use and contribute to relapse have not been identified. Here, using translating ribosome affinity purification (TRAP) profiling, electrophysiology, and behavior, we demonstrate that cholinergic neurons, but not peptidergic neurons, of the medial habenula (MHb) display spontaneous tonic firing of 2–10 Hz generated by hyperpolarization-activated cyclic nucleotide-gated (HCN) pacemaker channels and that infusion of the HCN pacemaker antagonist ZD7288 in the habenula precipitates somatic and affective signs of withdrawal. Further, we show that a strong, α3β4-dependent increase in firing frequency is observed in these pacemaker neurons upon acute exposure to nicotine. No change in the basal or nicotine-induced firing was observed in cholinergic MHb neurons from mice chronically treated with nicotine. We observe, however, that, during withdrawal, reexposure to nicotine doubles the frequency of pacemaking activity in these neurons. These findings demonstrate that the pacemaking mechanism of cholinergic MHb neurons controls withdrawal, suggesting that the heightened nicotine sensitivity of these neurons during withdrawal may contribute to smoking relapse. PMID:24082085

  3. Pre-ejection period by radial artery tonometry supplements echo doppler findings during biventricular pacemaker optimization

    Directory of Open Access Journals (Sweden)

    Qamruddin Salima

    2011-07-01

    Full Text Available Abstract Background Biventricular (Biv pacemaker echo optimization has been shown to improve cardiac output however is not routinely used due to its complexity. We investigated the role of a simple method involving computerized pre-ejection time (PEP assessment by radial artery tonometry in guiding Biv pacemaker optimization. Methods Blinded echo and radial artery tonometry were performed simultaneously in 37 patients, age 69.1 ± 12.8 years, left ventricular (LV ejection fraction (EF 33 ± 10%, during Biv pacemaker optimization. Effect of optimization on echo derived velocity time integral (VTI, ejection time (ET, myocardial performance index (MPI, radial artery tonometry derived PEP and echo-radial artery tonometry derived PEP/VTI and PEP/ET indices was evaluated. Results Significant improvement post optimization was achieved in LV ET (286.9 ± 37.3 to 299 ± 34.6 ms, p Conclusion An acute shortening of PEP by radial artery tonometry occurs post Biv pacemaker optimization and correlates with improvement in hemodynamics by echo Doppler and may provide a cost-efficient approach to assist with Biv pacemaker echo optimization.

  4. Surgical outcome of Fontan conversion and arrhythmia surgery: Need a pacemaker?

    Science.gov (United States)

    Terada, Takafumi; Sakurai, Hajime; Nonaka, Toshimichi; Sakurai, Takahisa; Sugiura, Junya; Taneichi, Tetsuyoshi; Ohtsuka, Ryohei

    2014-07-01

    Atrial tachyarrhythmias are frequent complications in the late period after the Fontan procedure, and important risk factors for a poor prognosis. The impact of Fontan conversion and arrhythmia surgery in failed Fontan patients has been described in many reports. We evaluated our experience with Fontan conversion procedures, concomitant arrhythmia surgery, and pacemaker implantation. We reviewed the hospital records of 25 consecutive patients who underwent a Fontan conversion procedure from January 2004 to March 2012. Twenty-four patients had arrhythmia surgery using cryoablation and radiofrequency ablation at the time of conversion. A bilateral atrial maze procedure was performed in 6 patients, right-side maze in 15, and isthmus block in 3. Three patients with a diagnosis of corrected transposition of the great arteries underwent simultaneous pacemaker implantation electively. There was no early death and one late death during a mean follow-up period of 21.2 months. Three tachyarrhythmia recurrences developed, and there were 4 occurrences of sinus bradycardia. Five of these patients required postoperative pacemaker implantation. The mid-term results of Fontan conversion and arrhythmia surgery in our institute were satisfactory. The occurrence of unexpected postoperative pacemaker requirement was high in the patients who underwent a right atrial or bilateral atrial maze procedure. Pacemaker or lead implantation is recommended for patients planned to undergo a right-side or full maze procedure. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  5. Iron-functionalized titanium dioxide on flexible glass fibers for photocatalysis of benzene, toluene, ethylbenzene, and o-xylene (BTEX) under visible- or ultraviolet-light irradiation.

    Science.gov (United States)

    Yang, Sung-Bong; Chun, Ho-Hwan; Tayade, Rajesh J; Jo, Wan-Kuen

    2015-03-01

    Iron-functionalized titanium dioxide (TiO2) composites with various Fe-to-Ti ratios were prepared on flexible glass fibers (GF-Fe-TiO2) via a sol-gel method, followed by a dip-coating process. The photocatalytic ability of these composites in degrading selected volatile organic compounds (VOCs; benzene, toluene, ethylbenzene, and o-xylene [BTEX]) at indoor concentration levels was examined. The GF-Fe-TiO2 composites were characterized using scanning electron microscopy, energy-dispersive X-ray elemental analysis, ultraviolet (UV)-visible spectroscopy, and X-ray diffraction. The GF-Fe-TiO2 composites showed superior photocatalytic performance to that of a reference glass fiber-supported TiO2 photocatalyst for the treatment of BTEX under visible light. However, this trend was reversed under UV irradiation. Specifically, the average BTEX photocatalytic efficiencies of the 0.01-GF-Fe-TiO2 composite in a 3-hr visible-light photocatalytic process were 4%, 33%, 51%, and 74%, respectively. Conversely, the average BTEX photocatalytic efficiencies obtained for GF-TiO2 were close to 0%, 5%, 16%, and 29%, respectively. These findings demonstrated that the GF-Fe-TiO2 composites could be applied to photocatalytically purify BTEX, especially under visible-light exposure. Moreover, the GF-Fe-TiO2 composites prepared with different Fe-to-Ti ratios displayed different BTEX photocatalytic decomposition efficiencies under visible or UV light, allowing for optimization of the Fe-to-Ti ratio (which was found to be 0.01). The application of nanomaterials for air purification necessitates a supporting material to stabilize them while in contact with the treated air in the photocatalytic chamber. Glass fibers have an obvious advantage over other supporting materials mainly because of its flexibility, which makes it much easier to handle. However, the applications of glass fiber-supported, visible light-activated photocatalysts to the treatment of air pollutants are rarely reported in

  6. Skill Flexibility among Schoolteachers: Operationalization and Organizational Implications.

    Science.gov (United States)

    Rosenblatt, Zehava; Inbal, Batia

    1999-01-01

    Investigates effects of skill flexibility on Israeli secondary teachers' work attitudes and job performance. Both role and functional flexibility were associated with improved teachers' work performance; role flexibility is linked to high organizational commitment and low powerlessness. Principals appreciate skill flexibility, but organizational…

  7. A Comparative Study on a Tilt-Integral-Derivative Controller with Proportional-Integral-Derivative Controller for a Pacemaker

    Directory of Open Access Journals (Sweden)

    Aysan Esgandanian

    2016-06-01

    Full Text Available The study is done to determine the comparison between proportional-integral-derivative controller (PID controller and tilt-integral-derivative (TID controller for cardiac pacemaker systems, which can automatically control the heart rate to accurately track a desired preset profile. The controller offers good adaption of heart to the physiological needs of the patient. The parameters of the both controllers are tuned by particle swarm optimization (PSO algorithm which uses the integral of time square error as a fitness function to be minimized. Simulation results are performed on the developed cardiovascular system of humans and results demonstrate that the TID controller produces superior control performance than PID controllers. In this paper all simulations were performed in Matlab.

  8. The dependence of radiofrequency induced pacemaker lead tip heating on the electrical conductivity of the medium at the lead tip.

    Science.gov (United States)

    Langman, Deborah A; Goldberg, Ira B; Judy, Jack; Paul Finn, J; Ennis, Daniel B

    2012-08-01

    Radiofrequency induced pacemaker lead tip heating is one of the main reasons magnetic resonance imaging (MRI) is contraindicated for patients with pacemakers. The objective of this work was to evaluate the dependence of pacemaker lead tip heating during MRI scanning on the electrical conductivity of the medium surrounding the pacemaker lead tip. The effect of conductivity was measured using hydroxyethyl cellulose, polyacrylic acid, and saline with conductivities ranging from 0 to 3 S/m which spans the range of human tissue conductivity. The maximum lead tip heating observed in polyacrylic acid was 50.4 °C at 0.28 S/m, in hydroxyethyl cellulose the maximum was 36.8 °C at 0.52 S/m, and in saline the maximum was 12.5 °C at 0.51 S/m. The maximum power transfer theorem was used to calculate the relative power deposited in the solution based on the characteristic impedance of the pacemaker lead and test solution impedance. The results demonstrate a strong correlation between the relative power deposited and pacemaker lead tip heating for hydroxyethyl cellulose and saline solutions. Maximum power deposition occurred when the impedance of the solution matched the pacemaker lead impedance. Pacemaker lead tip heating is dependent upon the electrical conductivity of the solution at the lead tip and should be considered when planning in vitro gel or saline experiments.

  9. Pacemaker activity of the human sinoatrial node: Role of the hyperpolarization-activated current, I-f

    NARCIS (Netherlands)

    A.O. Verkerk; A.C.G. van Ginneken; R. Wilders

    2009-01-01

    The mechanism of primary, spontaneous cardiac pacemaker activity of the sinoatrial node (SAN) has extensively been studied in several animal species, but is virtually unexplored in man. Understanding the mechanisms of human SAN pacemaker activity is important for developing new therapeutic approache

  10. Depressed pacemaker activity of sinoatrial node myocytes contributes to the age-dependent decline in maximum heart rate

    Science.gov (United States)

    Larson, Eric D.; St. Clair, Joshua R.; Sumner, Whitney A.; Bannister, Roger A.; Proenza, Cathy

    2013-01-01

    An inexorable decline in maximum heart rate (mHR) progressively limits human aerobic capacity with advancing age. This decrease in mHR results from an age-dependent reduction in “intrinsic heart rate” (iHR), which is measured during autonomic blockade. The reduced iHR indicates, by definition, that pacemaker function of the sinoatrial node is compromised during aging. However, little is known about the properties of pacemaker myocytes in the aged sinoatrial node. Here, we show that depressed excitability of individual sinoatrial node myocytes (SAMs) contributes to reductions in heart rate with advancing age. We found that age-dependent declines in mHR and iHR in ECG recordings from mice were paralleled by declines in spontaneous action potential (AP) firing rates (FRs) in patch-clamp recordings from acutely isolated SAMs. The slower FR of aged SAMs resulted from changes in the AP waveform that were limited to hyperpolarization of the maximum diastolic potential and slowing of the early part of the diastolic depolarization. These AP waveform changes were associated with cellular hypertrophy, reduced current densities for L- and T-type Ca2+ currents and the “funny current” (If), and a hyperpolarizing shift in the voltage dependence of If. The age-dependent reduction in sinoatrial node function was not associated with changes in β-adrenergic responsiveness, which was preserved during aging for heart rate, SAM FR, L- and T-type Ca2+ currents, and If. Our results indicate that depressed excitability of individual SAMs due to altered ion channel activity contributes to the decline in mHR, and thus aerobic capacity, during normal aging. PMID:24128759

  11. [The computer assisted pacemaker clinic at the regional hospital of Udine (author's transl)].

    Science.gov (United States)

    Feruglio, G A; Lestuzzi, L; Carminati, D

    1978-01-01

    For a close follow-up of large groups of pacemaker patients and for evaluation of long term pacing on a reliable statistical basis, many pacemaker centers in the world are now using computer systems. A patient data system with structured display records, designed to give complete, comprehensive and surveyable information and which are immediately retrievable 24 hours a day, on display or printed sets, seems to offer an ideal solution. The pacemaker clinic at the Regional Hospital of Udine has adopted this type of system. The clinic in linked to a live, on-line patient data system (G/3, Informatica Friuli-Venezia Giulia). The input and retrieval of information are made through a conventional keyboard. The input formats have fixed headings with coded alternatives and a limited space for comments in free text. The computer edits the coded information to surveyable reviews. Searches can be made on coded information and data of interest.

  12. Dynamic Breast Magnetic Resonance Imaging without Complications in a Patient with Dual-Chamber Demand Pacemaker

    Energy Technology Data Exchange (ETDEWEB)

    Sardanelli, F.; Lupo, P.; Esseridou, A.; Fausto, A.; Quarenghi, M. [Policlinico San Donato, San Donato Milanese, Milan (Italy). Depts. of Radiology, Arrhythmia and Electrophysiology Center

    2006-02-15

    Mammography and ultrasound indicated a cancer of the right breast in a 77-year-old woman with a dual-chamber demand pacemaker. The patient was not pacemaker-dependent. She underwent breast 1.5T magnetic resonance imaging (MRI) (dynamic gradient echo sequence with Gd-DOTA 0.1 mmol/kg). Before the patient entered the MR room, the configuration of the device was changed (the response to magnet was switched from asynchronous to off and the rate-responsive algorithm was disabled). No relevant modifications of heart rhythm or rate were observed during the MR examination. No symptom was reported. Immediately after the examination, the pacemaker interrogation showed neither program changes nor alert warnings. MRI detected a bifocal cancer in the right breast which allowed tailored breast-conserving treatment to be initiated. Histopathology confirmed a bifocal invasive ductal carcinoma.

  13. Transvenous extraction of an abandoned endocardial pacemaker lead in a dog.

    Science.gov (United States)

    LeBlanc, Nicole; Scollan, Katherine; Sisson, David

    2014-03-01

    A 6-year-old male castrated labrador retriever presented with endocardial pacemaker infection following migration and subsequent repositioning of the pulse generator. An epicardial lead and pulse generator were surgically implanted and the endocardial lead could not be removed with manual traction. The endocardial lead was severed, anchored, and abandoned at the thoracic inlet. The patient presented 4 months later with endocardial lead migration, bacteremia, and suspected glomerulonephritis. The endocardial pacemaker lead was transvenously extracted using a mechanical dilator sheath and locking stylet. This report of transvenous pacemaker lead extraction in a dog addresses the challenges and describes recent advances in extraction devices. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Pacemaker optimization guided by echocardiography in cardiac resynchronization therapy

    Directory of Open Access Journals (Sweden)

    Trifunović Danijela

    2009-01-01

    Full Text Available Introduction. Cardiac resynchronization therapy (CRT or biventricular pacing is a contemporary treatment in the management of advanced heart failure. Echocardiography plays an evolving and important role in patient selection for CRT, follow-up of acute and chronic CRT effects and optimization of device settings after biventricular pacemaker implantation. In this paper we illustrate usefulness of echocardiography for successful AV and VV timing optimization in patients with CRT. A review of up-to-date literature concerning rationale for AV and VV delay optimization, echocardiographic protocols and current recommendations for AV and VV optimization after CRT are also presented. Outline of Cases. The first case is of successful AV delay optimization guided by echocardiography in a patient with dilated cardiomyopathy treated with CRT is presented. Pulsed blood flow Doppler was used to detect mitral inflow while programming different duration of AV delay. The AV delay with optimal transmittal flow was established. The optimal mitral flow was the one with clearly defined E and A waves and maximal velocity time integral (VTI of the mitral flow. Improvement in clinical status and reverse left ventricle remodelling with improvement of ejection fraction was registered in our patient after a month. The second case presents a patient with heart failure caused by dilated cardiomyopathy; six months after CRT implantation the patient was still NYHA class III and with a significantly depressed left ventricular ejection fraction. Optimization of VV interval guided by echocardiography was undertaken measuring VTI of the left ventricular outflow tract (LVOT during programming of different VV intervals. The optimal VV interval was determined using a maximal LVOT VTI. A month after VV optimization our patient showed improvement in LV ejection fraction. Conclusion. Optimal management of patients treated with CRT integrate both clinical and echocardiographic follow

  15. Circadian pacemaker neurons change synaptic contacts across the day.

    Science.gov (United States)

    Gorostiza, E Axel; Depetris-Chauvin, Ana; Frenkel, Lia; Pírez, Nicolás; Ceriani, María Fernanda

    2014-09-22

    Daily cycles of rest and activity are a common example of circadian control of physiology. In Drosophila, rhythmic locomotor cycles rely on the activity of 150-200 neurons grouped in seven clusters [1, 2]. Work from many laboratories points to the small ventral lateral neurons (sLNvs) as essential for circadian control of locomotor rhythmicity [3-7]. sLNv neurons undergo circadian remodeling of their axonal projections, opening the possibility for a circadian control of connectivity of these relevant circadian pacemakers [8]. Here we show that circadian plasticity of the sLNv axonal projections has further implications than mere structural changes. First, we found that the degree of daily structural plasticity exceeds that originally described [8], underscoring that changes in the degree of fasciculation as well as extension or pruning of axonal terminals could be involved. Interestingly, the quantity of active zones changes along the day, lending support to the attractive hypothesis that new synapses are formed while others are dismantled between late night and the following morning. More remarkably, taking full advantage of the GFP reconstitution across synaptic partners (GRASP) technique [9], we showed that, in addition to new synapses being added or removed, sLNv neurons contact different synaptic partners at different times along the day. These results lead us to propose that the circadian network, and in particular the sLNv neurons, orchestrates some of the physiological and behavioral differences between day and night by changing the path through which information travels. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. The first batteryless, solar-powered cardiac pacemaker.

    Science.gov (United States)

    Haeberlin, Andreas; Zurbuchen, Adrian; Walpen, Sébastien; Schaerer, Jakob; Niederhauser, Thomas; Huber, Christoph; Tanner, Hildegard; Servatius, Helge; Seiler, Jens; Haeberlin, Heinrich; Fuhrer, Juerg; Vogel, Rolf

    2015-06-01

    Contemporary pacemakers (PMs) are powered by primary batteries with a limited energy-storing capacity. PM replacements because of battery depletion are common and unpleasant and bear the risk of complications. Batteryless PMs that harvest energy inside the body may overcome these limitations. The goal of this study was to develop a batteryless PM powered by a solar module that converts transcutaneous light into electrical energy. Ex vivo measurements were performed with solar modules placed under pig skin flaps exposed to different irradiation scenarios (direct sunlight, shade outdoors, and indoors). Subsequently, 2 sunlight-powered PMs featuring a 4.6-cm(2) solar module were implanted in vivo in a pig. One prototype, equipped with an energy buffer, was run in darkness for several weeks to simulate a worst-case scenario. Ex vivo, median output power of the solar module was 1963 μW/cm(2) (interquartile range [IQR] 1940-2107 μW/cm(2)) under direct sunlight exposure outdoors, 206 μW/cm(2) (IQR 194-233 μW/cm(2)) in shade outdoors, and 4 μW/cm(2) (IQR 3.6-4.3 μW/cm(2)) indoors (current PMs use approximately 10-20 μW). Median skin flap thickness was 4.8 mm. In vivo, prolonged SOO pacing was performed even with short irradiation periods. Our PM was able to pace continuously at a rate of 125 bpm (3.7 V at 0.6 ms) for 1½ months in darkness. Tomorrow's PMs might be batteryless and powered by sunlight. Because of the good skin penetrance of infrared light, a significant amount of energy can be harvested by a subcutaneous solar module even indoors. The use of an energy buffer allows periods of darkness to be overcome. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  17. Pacemaker Created in Human Ventricle by Depressing Inward-Rectifier K⁺ Current: A Simulation Study.

    Science.gov (United States)

    Zhang, Yue; Wang, Kuanquan; Li, Qince; Zhang, Henggui

    2016-01-01

    Cardiac conduction disorders are common diseases which cause slow heart rate and syncope. The best way to treat these diseases by now is to implant electronic pacemakers, which, yet, have many disadvantages, such as the limited battery life and infection. Biopacemaker has been expected to replace the electronic devices. Automatic ventricular myocytes (VMs) could show pacemaker activity, which was induced by depressing inward-rectifier K(+) current (I K1). In this study, a 2D model of human biopacemaker was created from the ventricular endocardial myocytes. We examined the stability of the created biopacemaker and investigated its driving capability by finding the suitable size and spatial distribution of the pacemaker for robust pacing and driving the surrounding quiescent cardiomyocytes. Our results suggest that the rhythm of the pacemaker is similar to that of the single cell at final stable state. The driving force of the biopacemaker is closely related to the pattern of spatial distribution of the pacemaker.

  18. Superior transseptal approach to mitral valve is associated with a higher need for pacemaker implantation than the left atrial approach

    DEFF Research Database (Denmark)

    Lukac, Peter; Hjortdal, Vibeke E; Pedersen, Anders K

    2006-01-01

    retrospectively evaluated. The surgeons used either the superior transseptal (group A) or left atrial approach (group B). The risk of pacemaker implantation associated with the superior transseptal approach as compared with the left atrial approach was estimated using the multivariate Cox regression analysis...... to adjust for possible confounders. RESULTS: We included 577 patients, 150 in group A and 427 in group B. Forty-four patients had a pacemaker implanted after the surgery; 17 in group A and 27 in group B (p = 0.010). The superior transseptal approach was an independent risk factor of pacemaker implantation...... in multivariate analysis (hazard ratio 2.2 [1.2 to 4.1], p = 0.014). Nineteen patients had a pacemaker implanted because of sinus node dysfunction; 9 in group A and 10 in group B (p = 0.017). Group A was an independent predictor of pacemaker implantation because of sinus node dysfunction in bivariate analyses...

  19. Gene- and cell-based bio-artificial pacemaker: what basic and translational lessons have we learned?

    Science.gov (United States)

    Li, R A

    2012-06-01

    Normal rhythms originate in the sino-atrial node, a specialized cardiac tissue consisting of only a few thousands of nodal pacemaker cells. Malfunction of pacemaker cells due to diseases or aging leads to rhythm generation disorders (for example, bradycardias and sick-sinus syndrome (SSS)), which often necessitate the implantation of electronic pacemakers. Although effective, electronic devices are associated with such shortcomings as limited battery life, permanent implantation of leads, lead dislodging, the lack of autonomic responses and so on. Here, various gene- and cell-based approaches, with a particular emphasis placed on the use of pluripotent stem cells and the hyperpolarization-activated cyclic nucleotide-gated-encoded pacemaker gene family, that have been pursued in the past decade to reconstruct bio-artificial pacemakers as alternatives will be discussed in relation to the basic biological insights and translational regenerative potential.

  20. Balance and flexibility.

    Science.gov (United States)

    2003-12-01

    The 'work-life balance' and flexible working are currently key buzz terms in the NHS. Those looking for more information on these topics should visit Flexibility at www.flexibility.co.uk for a host of resources designed to support new ways of working, including information on flexible workers and flexible rostering, the legal balancing act for work-life balance and home working.