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Sample records for valve thrombogenicity related

  1. A low-volume tester for the thrombogenic potential of mechanical heart valve prostheses.

    Science.gov (United States)

    Linde, Torsten; Hamilton, Kathrin F; Timms, Daniel L; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2011-09-01

    During the development of a mechanical heart valve prosthesis, many studies are conducted to guarantee its correct function. Currently, investigations into the thrombogenic potential of a valve after its replacement are conducted with expensive and time-consuming chronic animal trials. Hence, the study aim was to develop and test an alternative system to resolve such thrombogenic issues. The Thrombosis Tester of the Helmholtz Institute Aachen (THIA II) has a reasonably small priming volume (220-270 ml) that allows analysis of the thrombogenic potential of two valves, using one human blood bottle. Hydrodynamic evaluation demonstrated an absolutely stable physiological pressure and flow progression at the aortic and pulmonary positions. A sinus geometry of the human aortic root is implemented downstream of the valve in order to guarantee physiological leaflet motion. The tester remained absolutely thrombus-free during several tests carried out with minimally anticoagulated porcine blood, while the valves showed reproducible thrombus formation in reasonable locations. Tests with fully heparinized porcine blood showed that a soft silicon fixture for the valve could reduce hemolysis in the THIA II. This in-vitro test protocol can enable the optimization of a valve design during the early stages of its research and development. The system can provide a unique and suitable supplement to animal trials for testing thrombogenic performance, under constant and reproducible boundary conditions, including considerable physiological and pathological circumstances such as the influence of valve position (aortic, pulmonic), and a comparison of different valve types.

  2. Superhydrophobicity to minimize thrombogenic risk on mechanical heart valves

    Science.gov (United States)

    Bark, David; Vahabi, Hamed; Movafaghi, Sanli; Popat, Ketul; Kota, Arun K.; Dasi, Lakshmi Prasad

    2017-11-01

    A large number of prosthetic heart valves are implanted each year to treat heart valve disease, where half of the surgically replaced valves are mechanical heart valves (MHV)s. MHVs are at high risk for thrombosis and therefore require lifelong antithrombotic therapies, causing an increased bleeding risk that can lead to death. To alleviate this need, we investigate the potential of superhydrophobic surfaces in reducing the thrombotic risk. Particle imaging velocimetry and computational fluid dynamics are used to quantify shear stress in the presence of potential slip on the surface. Coagulation and cell adhesion are quantified by incubating blood under static conditions. We further evaluate a dynamic blood response in polydimethylsiloxane channels under complex shear conditions that mimic the hinge region of bileaflet mechanical heart valves, a region known to exhibit thrombosis. Overall, Shear stress is not reduced on a superhydrophobic bileaflet MHV. However, superhydrophobic surfaces significantly reduce the potential for platelet responses under static and dynamic blood flow conditions, a counterintuitive result when considering that hydrophobic surfaces are prone to protein and cell adhesion. The authors gratefully acknowledge funding from National Institutes of Health (NIH) under Award Number R01HL119824 and F32HL129730. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

  3. Towards Optimization of a Novel Trileaflet Polymeric Prosthetic Heart Valve Via Device Thrombogenicity Emulation (DTE)

    Science.gov (United States)

    Claiborne, Thomas E.; Xenos, Michalis; Sheriff, Jawaad; Chiu, Wei-Che; Soares, Joao; Alemu, Yared; Gupta, Shikha; Judex, Stefan; Slepian, Marvin J.; Bluestein, Danny

    2013-01-01

    Aortic stenosis the is most prevalent and life threatening form of valvular heart disease. It is primarily treated via open-heart surgical valve replacement with either a tissue or mechanical prosthetic heart valve (PHV), each prone to degradation and thrombosis, respectively. Polymeric PHVs may be optimized to eliminate these complications, and they may be more suitable for the new transcatheter aortic valve replacement (TAVR) procedure and in devices like the Total Artificial Heart. However, the development of polymer PHVs has been hampered by persistent in vivo calcification, degradation, and thrombosis. To address these issues, we have developed a novel surgically implantable polymer PHV comprised of a new thermoset polyolefin called xSIBS, in which key parameters were optimized for superior functionality via our Device Thrombogenicity Emulation (DTE) methodology. In this parametric study, we compared our homogeneous optimized polymer PHV to a prior composite polymer PHV and to a benchmark tissue valve. Our results show significantly improved hemodynamics and reduced thrombogenicity in the optimized polymer PHV compared to the other valves. These results indicate that our new design may not require anticoagulants and may be more durable than its predecessor, and validates the improvement, towards optimization, of this novel polymeric PHV design. PMID:23644615

  4. Hemodynamic Performance and Thrombogenic Properties of a Superhydrophobic Bileaflet Mechanical Heart Valve

    Science.gov (United States)

    Bark, David L.; Vahabi, Hamed; Bui, Hieu; Movafaghi, Sanli; Moore, Brandon; Kota, Arun K.; Popat, Ketul; Dasi, Lakshmi P.

    2016-01-01

    In this study, we explore how blood-material interactions and hemodynamics are impacted by rendering a clinical quality 25 mm St. Jude Medical Bileaflet mechanical heart valve (BMHV) superhydrophobic (SH) with the aim of reducing thrombo-embolic complications associated with BMHVs. Basic cell adhesion is evaluated to assess blood-material interactions, while hemodynamic performance is analyzed with and without the SH coating. Results show that a SH coating with a receding contact angle (CA) of 160º strikingly eliminates platelet and leukocyte adhesion to the surface. Alternatively, many platelets attach to and activate on pyrolytic carbon (receding CA=47), the base material for BMHVs. We further show that the performance index increases by 2.5% for coated valve relative to an uncoated valve, with a maximum possible improved performance of 5%. Both valves exhibit instantaneous shear stress below 10 N/m2 and Reynolds Shear Stress below 100 N/m2. Therefore, a SH BMHV has the potential to relax the requirement for antiplatelet and anticoagulant drug regimens typically required for patients receiving MHVs by minimizing blood-material interactions, while having a minimal impact on hemodynamics. We show for the first time that SH-coated surfaces may be a promising direction to minimize thrombotic complications in complex devices such as heart valves. PMID:27098219

  5. Force measuring valve assemblies, systems including such valve assemblies and related methods

    Science.gov (United States)

    DeWall, Kevin George [Pocatello, ID; Garcia, Humberto Enrique [Idaho Falls, ID; McKellar, Michael George [Idaho Falls, ID

    2012-04-17

    Methods of evaluating a fluid condition may include stroking a valve member and measuring a force acting on the valve member during the stroke. Methods of evaluating a fluid condition may include measuring a force acting on a valve member in the presence of fluid flow over a period of time and evaluating at least one of the frequency of changes in the measured force over the period of time and the magnitude of the changes in the measured force over the period of time to identify the presence of an anomaly in a fluid flow and, optionally, its estimated location. Methods of evaluating a valve condition may include directing a fluid flow through a valve while stroking a valve member, measuring a force acting on the valve member during the stroke, and comparing the measured force to a reference force. Valve assemblies and related systems are also disclosed.

  6. Corneal Lymphatic Valve Formation in Relation to Lymphangiogenesis

    Science.gov (United States)

    Truong, Tan; Huang, Eric; Yuen, Don; Chen, Lu

    2014-01-01

    Purpose. We have recently provided evidence showing that luminal lymphatic valves are formed right after the onset of corneal inflammatory lymphangiogenesis (LG). The purpose of this study was to further characterize the long-term time course, spatial distribution, directional orientation, and functional implications of the valve formation in relation to corneal LG. Methods. Corneal LG was induced in normal adult BALB/c mice by a modified suture placement model with equal distribution in the nasal and temporal side. Whole-mount corneas were harvested every 2 weeks for up to 8 weeks post suturing for immunofluorescent microscopic assays. Quantitative analysis on both lymphatic vessels and valves was performed by using National Institutes of Health ImageJ software. Corneal lymphatic live imaging was performed to show functional drainage of the valves. Results. Lymphatic vessel invasion areas at 4, 6, and 8 weeks were significantly less than the peak at 2 weeks post corneal suturing. In contrast, the ratio of lymphatic valves to vessel invasion area was at its lowest at 2 weeks with a peak approximately at 6 weeks post suturing. Lymphatic valves were more localized in the nasal quadrant at all time points studied, and most of the well-formed valves were directionally oriented toward the limbus. The lymphatic valves function to guide lymphatic drainage outside the cornea. Conclusions. This study presents new insights into corneal lymphatic valve formation and function in inflammatory LG. Further investigation on lymphatic valves may provide novel strategies to interfere with lymphatic maturation and function and to treat lymphatic-related disorders. PMID:24595382

  7. Corneal lymphatic valve formation in relation to lymphangiogenesis.

    Science.gov (United States)

    Truong, Tan; Huang, Eric; Yuen, Don; Chen, Lu

    2014-03-25

    We have recently provided evidence showing that luminal lymphatic valves are formed right after the onset of corneal inflammatory lymphangiogenesis (LG). The purpose of this study was to further characterize the long-term time course, spatial distribution, directional orientation, and functional implications of the valve formation in relation to corneal LG. Corneal LG was induced in normal adult BALB/c mice by a modified suture placement model with equal distribution in the nasal and temporal side. Whole-mount corneas were harvested every 2 weeks for up to 8 weeks post suturing for immunofluorescent microscopic assays. Quantitative analysis on both lymphatic vessels and valves was performed by using National Institutes of Health ImageJ software. Corneal lymphatic live imaging was performed to show functional drainage of the valves. Lymphatic vessel invasion areas at 4, 6, and 8 weeks were significantly less than the peak at 2 weeks post corneal suturing. In contrast, the ratio of lymphatic valves to vessel invasion area was at its lowest at 2 weeks with a peak approximately at 6 weeks post suturing. Lymphatic valves were more localized in the nasal quadrant at all time points studied, and most of the well-formed valves were directionally oriented toward the limbus. The lymphatic valves function to guide lymphatic drainage outside the cornea. This study presents new insights into corneal lymphatic valve formation and function in inflammatory LG. Further investigation on lymphatic valves may provide novel strategies to interfere with lymphatic maturation and function and to treat lymphatic-related disorders.

  8. Comparison of modified chandler, roller pump, and ball valve circulation models for in vitro testing in high blood flow conditions: application in thrombogenicity testing of different materials for vascular applications.

    Science.gov (United States)

    van Oeveren, Wim; Tielliu, Ignace F; de Hart, Jurgen

    2012-01-01

    Three different models, a modified Chandler loop, roller pump, and a new ball valve model (Hemobile), were compared with regard to intrinsic damage of blood components and activation of platelets. The Hemobile was used for testing of polymer tubes. High flow was not possible with the Chandler loop. The roller pump and the Hemobile could be adjusted to high flow, but he pump induced hemolysis. Platelet numbers were reduced in the roller pump and Chandler loop (P Dyneema Purity UHMWPE fiber and PET fiber based tubes, all showed hemolysis below 0.2% and reduced platelet count and function. Binding of fibrin and platelets was higer on PET, inflammatory markers were lowest on Dyneema Purity UHMWPE. We concluded that the Hemobile minimally affects blood and could be adjusted to high blood flows, simulating arterial shear stress. The Hemobile was used to measure hemocompatibility of graft material and showed Dyneema Purity UHMWPE fiber in many ways more hemocompatible than ePTFE and PET.

  9. Blast Valve Design and Related Studies : A Review

    OpenAIRE

    Sharma, P.K.; Patel, B. P.; Harbans Lal

    2016-01-01

    The protective structures required for performing critical operations are vulnerable to the blast and shock loads of advanced weapons. A blast valve is an important component of such structures for ventilation during normal conditions and for protection from blast/ shock during explosion. In this paper, various aspects of blast valve design and related studies are briefly reviewed. The concept and effects of blast wave, blast impact, numerical modelling and deformation of circular plate (one ...

  10. Towards reducing thrombogenicity of LVAD therapy: optimizing surgical and patient management strategies

    Science.gov (United States)

    Chivukula, Venkat Keshav; Lafzi, Ali; Mokadam, Nahush; Beckman, Jennifer; Mahr, Claudius; Aliseda, Alberto

    2017-11-01

    Unfavourable hemodynamics in heart failure patients implanted with left ventricular assist devices (LVAD), due to non-optimal surgical configurations and patient management, strongly influence thrombogenicity. This is consistent with the increase in devastating thromboembolic complications (specifically thrombosis and stroke) in patients, even as the risk of thrombosis inside the device decreases with modern designs. Inflow cannula and outflow graft surgical configurations have been optimized via patient-specific modeling that computes the thrombogenic potential with a combination of Eulerian (endothelial) wall shear stress and Lagrangian (platelet shear history) tracking. Using this view of hemodynamics, the benefits of intermittent aortic valve opening (promoting washout and reducing stagnant flow in the aortic valve region) have been assessed in managing the patient's residual native cardiac output. The use of this methodology to understand the contribution of the hemodynamics in the flow surrounding the LVAD itself to thrombogenesis show promise in developing holistic patient-specific management strategies to minimize stroke risk and enhance efficacy of LVAD therapy. Funded in part by an AHA postdoctoral fellowship 16POST30520004.

  11. Resource utilization and procedure-related costs associated with transfemoral transcatheter aortic valve replacement.

    Science.gov (United States)

    Klein, Holger; Boleckova, Jana

    2017-06-01

    Transcatheter aortic valve implantation (TAVI) is an alternative to surgical valve replacement for patients with aortic stenosis (AS). This study assessed the impact of changing from a self-expandable (SE) valve to a balloon-expandable (BE) valve on healthcare resource use and procedural costs in a population of inoperable AS patients. In this retrospective single center study, data for 195 patients who received either an SE or a BE valve between 2010-2014 were collected. Procedural and post-procedural healthcare resource use and cost parameters were determined for the two groups. The study showed that overall procedural time, including time required by medical personnel, was significantly shorter for TAVI using a BE compared with an SE valve. Post-surgery, patients in the BE valve group had significantly shorter hospital stays than the SE valve group, including significantly fewer days spent in the intensive care unit (ICU). Additionally, trends towards reduced 30-day mortality, incidence of new permanent pacemaker implantation, and incidence of blood transfusion were observed in the BE valve group compared with the SE valve group. Finally, total procedural costs were 24% higher in the SE compared with the BE valve group. The BE valve data were acquired in a single year, whereas the SE valve data were from a 5-year period. However, a year-by-year analysis of patient characteristics and study outcomes for the SE valve group showed few significant differences over this 5-year period. Overall, changing from an SE to a BE valve for TAVI in patients with severe AS reduced both healthcare resource use and procedure-related costs, while maintaining patient safety. For healthcare providers, this could increase efficiency and capacity within the healthcare system, with the added advantage of reducing costs.

  12. Serotonergic mechanisms enhance platelet-mediated thrombogenicity.

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    Galan, Ana M; Lopez-Vilchez, Irene; Diaz-Ricart, Maribel; Navalon, Fulgencio; Gomez, Esther; Gasto, Cristobal; Escolar, Gines

    2009-09-01

    Although it is generally acknowledged that serotonin (5-HT) is a weak agonist for human platelets, recent information suggests an association between serotonergic mechanisms and cardiovascular risk. We investigated the action of 5-HT on adhesive, cohesive and procoagulant properties of human platelets. Impact of 5-HT on whole blood coagulation and thrombin generation was measured by modified thromboelastometry (TEM) and specific fluorogenic assays. We evaluated the effects of 5-HT on thrombus formation in an in-vitro model of thrombosis using human flowing blood. In platelet-rich plasma (PRP), 5-HT favoured the expression of CD62-P, and procoagulant molecules on platelet membranes. These effects were potentiated in the presence of Ca(++) and/or ADP. Incubation with 5-HT accelerated clotting times and augmented clot strength in whole blood TEM, and enhanced thrombin generation in PRP. In perfusion studies, 5-HT significantly increased fibrin deposition at low shear (300s(-1)) and enhanced platelet thrombus formation on the damaged vascular surface at high shear (1,200s(-1)). Selective inhibition of serotonin reuptake (SSRI) attenuated effects of 5-HT on platelet activation and downregulated the prothrombotic tendencies observed in the previous experimental conditions. In general, reductions of thrombogenic patterns observed with SSRI were more evident under shear conditions (aggregation and perfusion systems) and less evident under steady conditions (TEM and thrombin generation assays). In conclusion, 5-HT is not a weak agonist for human platelets; instead it accentuates platelet activation, potentiates procoagulant responses on human blood and increases thrombogenesis on damaged vascular surfaces. The remarkable antithrombotic actions achieved through SSRI deserve further mechanistic and clinical investigations.

  13. A review of fluid-structure interaction simulations of prosthetic heart valves.

    Science.gov (United States)

    Borazjani, Iman

    2015-01-01

    Dysfunctional natural heart valves are replaced with prosthetic heart valves through surgery. However, prosthetic valves are far from ideal. Bioprosthetic heart valves (BHVs) suffer from early calcification and structural damages. Mechanical heart valves (MHVs) are durable but highly thrombogenic and require lifelong anticoagulant treatment. These complications are believed to be related to nonphysiologic flow patterns created by these valves. Fluid-structure interaction (FSI) simulations are essential in revealing the hemodynamics of these valves. By combining the three-dimensional (3D) flow field obtained from realistic FSI simulations with platelet activation models, nonphysiologic flow patterns can be identified. In this review paper, state-of-the-art methods for simulating FSI in heart valves are reviewed, and the flow physics uncovered by FSI simulations are discussed. Finally, the limitations of current methods are discussed, and future research directions are proposed as follows: (1) incorporation of realistic, image-based ventricle and atrium geometries; (2) comparing MHV and BHV under similar conditions to identify nonphysiologic flow patterns; (3) developing better models to estimate platelet activation potential to be incorporated into the simulations; and (4) identifying the optimum placement of the valves in both mitral and aortic positions.

  14. Abnormalities in thrombogenic and rheologic factors in Nigerian hypertensive patients.

    Science.gov (United States)

    Ogunlade, O A; Fasanmade, A A

    2001-12-01

    Platelet aggregation, plasma viscosity and plasma fibrinogen concentration were measured in 20 hypertensive Nigerian patients (10 males and 10 females) aged 32-72 years. Another 20 patients gender-matched normotensive subjects, served as controls. Platelet aggregate ratio was significantly lower (P < 0.05) in hypertensive (0.38 +/- 0.24) than in normotensive subjects (0.80 +/- 0.19). The relative plasma viscosity of the hypertensive patients (2.04 +/- 0.14) was higher (P < 0.05) than the value in control subjects (1.64 +/- 0.25). Plasma fibrinogen concentration, determined by the direct clot weight technique, was also significantly higher (p < 0.05) in hypertensive patients (3.90 +/- 0.62mg/dL) than in normotensive patients (2.70 +/- 0.60mg/dL). There was no evidence of gender differences in all the above variables except in the plasma fibrinogen concentration, which was significantly higher (P < 0.01) in male hypertensive patients. It is thus evident that haemorheological and thrombogenic abnormalities may be present in hypertensive Nigerian patients at the time of diagnosis and therapeutic interventions that reduce the risk of thrombogenesis and rheologic abnormalities should be considered in the management of Nigerian patients with hypertension.

  15. Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

    Science.gov (United States)

    Ramaswamy, Sharan; Salinas, Manuel; Carrol, Rob; Landaburo, Karla; Ryans, Xavier; Crespo, Cynthia; Rivero, Ailyn; Al-Mousily, Faris; DeGroff, Curt; Bleiweis, Mark; Yamaguchi, Hitomi

    2013-01-01

    Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of tri-leaflet polymer valve prostheses. However, identification of a protocol for initial assessment of polymer valve hydrodynamic functionality is paramount during the early stages of the design process. Traditional in vitro pulse duplicator systems are not configured to accommodate flexible tri-leaflet materials; in addition, assessment of polymer valve functionality needs to be made in a relative context to native and prosthetic heart valves under identical test conditions so that variability in measurements from different instruments can be avoided. Accordingly, we conducted hydrodynamic assessment of i) native (n = 4, mean diameter, D = 20 mm), ii) bi-leaflet mechanical (n= 2, D = 23 mm) and iii) polymer valves (n = 5, D = 22 mm) via the use of a commercially available pulse duplicator system (ViVitro Labs Inc, Victoria, BC) that was modified to accommodate tri-leaflet valve geometries. Tri-leaflet silicone valves developed at the University of Florida comprised the polymer valve group. A mixture in the ratio of 35:65 glycerin to water was used to mimic blood physical properties. Instantaneous flow rate was measured at the interface of the left ventricle and aortic units while pressure was recorded at the ventricular and aortic positions. Bi-leaflet and native valve data from the literature was used to validate flow and pressure readings. The following hydrodynamic metrics were reported: forward flow pressure drop, aortic root mean square forward flow rate, aortic closing, leakage and regurgitant volume, transaortic closing, leakage, and total energy losses. Representative results indicated that hydrodynamic metrics from the three valve groups could be successfully obtained by incorporating a custom-built assembly into a commercially available pulse duplicator system and subsequently, objectively compared to provide

  16. [Early thrombogenic problems in the sparks-prothesis (author's transl)].

    Science.gov (United States)

    Kleine, H O; Stockmann, U

    1975-04-01

    Some patients with Sparks arterial bypass graft show just during the operation a thrombosis in the prothesis. After the rubber rod has been pulled off, thrombogenic substances can be washed out of the prothesis-lumen. They shorten the clotting time of the patients' venous blood. 1000 ml 0.0% NaCl prevent this early thrombosis in the arterial bypass graft.

  17. The influence of biomaterials on endothelial cell thrombogenicity

    Science.gov (United States)

    McGuigan, Alison P.; Sefton, Michael V.

    2007-01-01

    Driven by tissue engineering and regenerative medicine, endothelial cells are being used in combination with biomaterials in a number of applications for the purpose of improving blood compatibility and host integration. Endothelialized vascular grafts are beginning to be used clinically with some success in some centers, while endothelial seeding is being explored as a means of creating a vasculature within engineered tissues. The underlying assumption of this strategy is that when cultured on artificial biomaterials, a confluent layer of endothelial cells maintain their non-thrombogenic phenotype. In this review the existing knowledge base of endothelial cell thrombogenicity cultured on a number of different biomaterials is summarized. The importance of selecting appropriate endpoint measures that are most reflective of overall surface thrombogenicity is the focus of this review. Endothelial cells inhibit thrombosis through three interconnected regulatory systems (1) the coagulation cascade (2) the cellular components of the blood such as leukocytes and platelets and (3) the complement cascade, and also through effects on fibrinolysis and vascular tone, the latter which influences blood flow. Thus, in order to demonstrate the thromobgenic benefit of seeding a biomaterial with EC, the conditions under which EC surfaces are more likely to exhibit lower thrombogenicity than unseeded biomaterial surfaces need to be consistent with the experimental context. The endpoints selected should be appropriate for the dominant thrombotic process that occurs under the given experimental conditions. PMID:17316788

  18. Conjunctival complications related to Ahmed glaucoma valve insertion.

    Science.gov (United States)

    Geffen, Noa; Buys, Yvonne M; Smith, Michael; Anraku, Ayako; Alasbali, Tariq; Rachmiel, Ronny; Trope, Graham E

    2014-02-01

    Conjunctival complications may occur after glaucoma drainage device surgery. We analyzed the frequency, risk factors, management and outcomes of Ahmed glaucoma valve (AGV)-related conjunctival complications. Retrospective review of postoperative conjunctival complications in patients undergoing AGV insertion. Only subjects with ≥1-year follow-up were included. The charts of 158 subjects with a median age of 64±16.2 years were reviewed. Median follow-up was 43.5 months (range, 12 to 103 mo). Fifty-three (33.5%) wound dehiscences and 14 (8.9%) device exposures were diagnosed 31.6±35.7 and 996±735 days after procedure, respectively (PAGV insertion. It does not need repair as long as the tube is well covered. AGV tube or plate exposures are less common, occur later and were promptly repaired as per current practice. Important factors predisposing to these problems include a greater number of preoperative hypotensive medications and the implantation quadrant.

  19. Global strain in severe aortic valve stenosis: relation to clinical outcome after aortic valve replacement.

    Science.gov (United States)

    Dahl, Jordi S; Videbæk, Lars; Poulsen, Mikael K; Rudbæk, Torsten R; Pellikka, Patricia A; Møller, Jacob E

    2012-09-01

    Global longitudinal systolic strain (GLS) is often reduced in aortic stenosis despite normal ejection fraction. The importance of reduced preoperative GLS on long-term outcome after aortic valve replacement is unknown. A total of 125 patients with severe aortic stenosis and ejection fraction >40% scheduled for aortic valve replacement were evaluated preoperatively and divided into 4 groups according to GLS quartiles. Patients were followed up for 4 years. The primary end points were major adverse cardiac events (MACEs) defined as cardiovascular mortality and cardiac hospitalization because of worsening of heart failure; the secondary end point was cardiovascular mortality. MACE and cardiac mortality were significantly increased in patients with lower GLS. Estimated 5-year MACE was increased: first quartile 19% (n=6) / second quartile 20% (n=6) / third quartile 35% (n=11) / fourth quartile 49% (n=15); P=0.04. Patients with increased age, left ventricular hypertrophy, and left atrial dilatation were at increased risk. In Cox regression analysis, after correcting for standard risk factors and ejection fraction, GLS was found to be significantly associated with cardiac morbidity and mortality. In a stepwise Cox model with forward selection, GLS was the sole independent predictor: hazard ratio=1.13 (95% confidence interval, 1.02-1.25), P=0.04. Comparing the overall log likelihood χ(2) of the predictive power of the multivariable model containing GLS was statistically superior to models based on EuroScore, history with ischemic heart disease, and ejection fraction. In patients with symptomatic severe aortic stenosis undergoing aortic valve replacement, reduced GLS provides important prognostic information beyond standard risk factors.

  20. Tricuspid valve endocarditis following central venous cannulation: The increasing problem of catheter related infection

    Directory of Open Access Journals (Sweden)

    Suresh Babu Kale

    2013-01-01

    Full Text Available A central venous catheter (CVC is inserted for measurement of haemodynamic variables, delivery of nutritional supplements and drugs and access for haemodialysis and haemofiltration. Catheterization and maintenance are common practices and there is more to the technique than routine placement as evident when a procedure-related complication occurs. More than 15% of the patients who receive CVC placement have some complications and infectious endocarditis involving the tricuspid valve is a rare and serious complication with high morbidity and mortality. Overenthusiastic and deep insertion of the guide wire and forceful injection through the CVC may lead to injury of the tricuspid valve and predispose to bacterial deposition and endocarditis. We report a case of tricuspid valve endocarditis, probably secondary to injury of the anterior tricuspid leaflet by the guide wire or the CVC that required open heart surgery with vegetectomy and repair of the tricuspid valve.

  1. Long-term tricuspid valve prosthesis-related complications in patients with congenital heart disease.

    Science.gov (United States)

    van Slooten, Ymkje J; Freling, Hendrik G; van Melle, Joost P; Mulder, Barbara J M; Jongbloed, Monique R M; Ebels, Tjark; Voors, Adriaan A; Pieper, Petronella G

    2014-01-01

    In patients with acquired valvar disease, morbidity and mortality rates after tricuspid valve replacement (TVR) are high. However, in adult patients with congenital heart disease, though data concerning outcome after TVR are scarce, even poorer results are suggested in patients with Ebstein anomaly. To investigate the applicability of these results to a broader array of congenital heart disease patients, we report the long-term follow-up of prosthesis-related complications, including re-replacement of patients with a tricuspid valve prosthesis and congenital heart disease. From the Dutch Congenital Corvitia (CONCOR) registry, we identified 20 patients with a biological or mechanical tricuspid valve prosthesis implanted between 1977 and 2012 (total of 31 prostheses). We analysed the tricuspid valve-related complications and mortality. Ten patients with a median age of 16.2 years at the time of surgery (interquartile range 13.2-28.2 years) received a bioprosthesis while 10 patients with a median age of 36.4 years (interquartile range 14.0-47.0) at the time of surgery received a mechanical prosthesis (P = 0.28). During a mean follow-up of 14 years, 50% needed a re-replacement because of valve-related complications (e.g. valve degeneration or valve thrombosis). The yearly percentage of patients with valve-related complications was 4.2% in patients with a bioprosthesis and 2.7% in those with a mechanical prosthesis. Within 20 years of implantation, the median duration of event-free survival was significantly shorter in 3 patients with a prosthesis-patient mismatch (PPM; 1.0 year; interquartile range 0.01-2.6), compared with 7 without mismatch (8.0 years; interquartile range 5.1-12.3; P = 0.02). Compared with previous literature on acquired valvar disease, we found a higher incidence of valve-related complications in patients with congenital heart disease that was unrelated to prosthesis material. Our data suggest that PPM may have a negative effect on the event

  2. [Related research on mechanical property of valve membrane in transcatheter bioprosthesis valve based on the chemical modification and cutting technology].

    Science.gov (United States)

    Chen, Dakai; Li, Yu; Luo, Qiyi; Liu, Baolin; Chen, Kangmin

    2014-08-01

    The aim of this research is to investigate the preparation method of valve membrane in transcatheter bio- prosthetic valve, and to study the effect of chemical modification and cutting technology to tensile property and suture force property of valve membrane. We carried out a series of processes to perform the tests, such as firstly to test the crosslinking degree of valve membrane using ninhydrin method, then to test the tensile property and suture force property by using Instron's biomechanicAl testing equipment, and then to observe the collagen fiber orientation in valve membrane using Instron's biomechanical testing equipment and using field emission scanning electron microscopy. The study indicated that after the chemical modification, the crosslinking degree, tensile strength and suture force strength increasing rate of valve membrane were 93.78% ± 3. 2%, (8.24 ± 0.79) MPa, 102%, respectively. The valve membrane had a better biomechanical property and would be expected to become valve membrane in transcatheter bioprosthesis valve.

  3. Microparticle-Induced Coagulation Relates to Coronary Artery Atherosclerosis in Severe Aortic Valve Stenosis.

    Directory of Open Access Journals (Sweden)

    Patrick Horn

    Full Text Available Circulating microparticles (MPs derived from endothelial cells and blood cells bear procoagulant activity and promote thrombin generation. Thrombin exerts proinflammatory effects mediating the progression of atherosclerosis. Aortic valve stenosis may represent an atherosclerosis-like process involving both the aortic valve and the vascular system. The aim of this study was to investigate whether MP-induced thrombin generation is related to coronary atherosclerosis and aortic valve calcification.In a cross-sectional study of 55 patients with severe aortic valve stenosis, we assessed the coronary calcification score (CAC as indicator of total coronary atherosclerosis burden, and aortic valve calcification (AVC by computed tomography. Thrombin-antithrombin complex (TATc levels were measured as a marker for thrombin formation. Circulating MPs were characterized by flow cytometry according to the expression of established surface antigens and by measuring MP-induced thrombin generation.Patients with CAC score below the median were classified as patients with low CAC, patients with CAC Score above the median as high CAC. In patients with high CAC compared to patients with low CAC we detected higher levels of TATc, platelet-derived MPs (PMPs, endothelial-derived MPs (EMPs and MP-induced thrombin generation. Increased level of PMPs and MP-induced thrombin generation were independent predictors for the severity of CAC. In contrast, AVC Score did not differ between patients with high and low CAC and did neither correlate with MPs levels nor with MP-induced thrombin generation.In patients with severe aortic valve stenosis MP-induced thrombin generation was independently associated with the severity of CAC but not AVC indicating different pathomechanisms involved in coronary artery and aortic valve calcification.

  4. Relation of aortic valve calcium to chronic kidney disease (from the Chronic Renal Insufficiency Cohort Study).

    Science.gov (United States)

    Guerraty, Marie A; Chai, Boyang; Hsu, Jesse Y; Ojo, Akinlolu O; Gao, Yanlin; Yang, Wei; Keane, Martin G; Budoff, Matthew J; Mohler, Emile R

    2015-05-01

    Although subjects with chronic kidney disease (CKD) are at markedly increased risk for cardiovascular mortality, the relation between CKD and aortic valve calcification has not been fully elucidated. Also, few data are available on the relation of aortic valve calcification and earlier stages of CKD. We sought to assess the relation of aortic valve calcium (AVC) with estimated glomerular filtration rate (eGFR), traditional and novel cardiovascular risk factors, and markers of bone metabolism in the Chronic Renal Insufficiency Cohort (CRIC) Study. All patients who underwent aortic valve scanning in the CRIC study were included. The relation between AVC and eGFR, traditional and novel cardiovascular risk factors, and markers of calcium metabolism were analyzed using both unadjusted and adjusted regression models. A total of 1,964 CRIC participants underwent computed tomography for AVC quantification. Decreased renal function was independently associated with increased levels of AVC (eGFR 47.11, 44.17, and 39 ml/min/1.73 m2, respectively, p<0.001). This association persisted after adjusting for traditional, but not novel, AVC risk factors. Adjusted regression models identified several traditional and novel risk factors for AVC in patients with CKD. There was a difference in AVC risk factors between black and nonblack patients. In conclusion, our study shows that eGFR is associated in a dose-dependent manner with AVC in patients with CKD, and this association is independent of traditional cardiovascular risk factors. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Thrombogenicity tests on ar-irradiated polycarbonate foils

    Energy Technology Data Exchange (ETDEWEB)

    Trindade, Gustavo F.; Rizzutto, Marcia A.; Silva, Tiago F.; Moro, Marcos V.; Added, Nemitala; Tabacniks, Manfredo H., E-mail: g.ferraz@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. de Fisica; Delgado, Adriana O. [Universidade Federal de Sao Carlos (UFSCAR), Sorocaba, SP (Brazil); Cunha, Tatiana F. [Biosintesis P and D do Brasil, Sao Paulo, SP (Brazil); Higa, Olga Z. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Biotecnologia

    2013-07-01

    Understanding polymer surface properties is extremely important for the most wide range of their applications, from basic coating to the most complex composites and biomaterials. Low energy ion beam irradiation of polymer can improve such surface properties. By modifying its surface biocompatibility, polymers are excellent candidates for biomaterials, due to its malleability and low weight, when compared to metals. In this work, we irradiated 30-μm Bisphenol-A Polycarbonate foils with 23-keV Argon ion beam at six different doses. Aluminium foils were simultaneously irradiated in order to measure the doses by Rutherford Backscattering Spectroscopy. The surface modifications after the argon ion beam irradiation were analyzed by water contact angle measurements and atomic force microscopy. Platelet adhesion tests were used in order to investigate thrombogenicity, showing a growing tendency with the irradiated Argon dose. (author)

  6. Severe aortic valve stenosis in the elderly: high prevalence of sleep-related breathing disorders

    Directory of Open Access Journals (Sweden)

    Keymel S

    2015-09-01

    Full Text Available Stefanie Keymel,1 Katharina Hellhammer,1 Tobias Zeus,1 Marc Merx,2 Malte Kelm,1 Stephan Steiner3 1Department of Cardiology, Pneumology, and Vascular Diseases, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, 2Department of Cardiology, Vascular Diseases and Intensive Care Medicine, KRHKlinikum Robert Koch Gehrden, Gehrden, 3Department of Cardiology, Pneumology and Intensive Care Medicine, St Vincenz Hospital, Limburg, Germany Background: Aortic valve stenosis is common in the elderly, with a prevalence of nearly 3% in patients aged 75 years or older. Despite the fact that sleep-related breathing disorders (SRBD are thought to be associated with cardiac disease, little is known about their prevalence in this patient cohort. The purpose of this study was to evaluate the prevalence of SRBD in older patients with aortic valve stenosis admitted for transcatheter aortic valve implantation.Methods: Forty-eight consecutive patients (mean age 81±6 years; 37.5% male with symptomatic aortic valve stenosis and considered for transcatheter aortic valve replacement were screened for SRBD. Sleep studies were performed by in-hospital unattended cardiorespiratory polygraphy measuring nasal air flow, chest and abdominal efforts, as well as oxygen saturation and body position. The patients were divided in subgroups dependent on the documented apnea–hypopnea index (AHI; no SRBD was defined as an AHI of <5 events/hour; mild SRBD as AHI 5–15 events/hour, and moderate to severe SRBD as AHI ≥15 events/hour.Results: Thirty-seven patients (77% had SRBD defined as an AHI of ≥5 events/hour. Eleven patients had an unremarkable investigation, with AHI <5 events/hour (mean 3.0±1.3 events/hour. Among patients with sleep apnea, 19 patients had mild SRBD, with an AHI of 5–15 events/hour (mean 9.9±3.4 events/hour and 18 patients had moderate to severe SRBD (mean 26.6±11.3 events/hour. Mainly, obstructive apneas were found. Subgroups were not

  7. New insights into valve-related intramural and intracellular bacterial diversity in infective endocarditis.

    Directory of Open Access Journals (Sweden)

    Andreas Oberbach

    Full Text Available In infective endocarditis (IE, a severe inflammatory disease of the endocardium with an unchanged incidence and mortality rate over the past decades, only 1% of the cases have been described as polymicrobial infections based on microbiological approaches. The aim of this study was to identify potential biodiversity of bacterial species from infected native and prosthetic valves. Furthermore, we compared the ultrastructural micro-environments to detect the localization and distribution patterns of pathogens in IE.Using next-generation sequencing (NGS of 16S rDNA, which allows analysis of the entire bacterial community within a single sample, we investigated the biodiversity of infectious bacterial species from resected native and prosthetic valves in a clinical cohort of 8 IE patients. Furthermore, we investigated the ultrastructural infected valve micro-environment by focused ion beam scanning electron microscopy (FIB-SEM.Biodiversity was detected in 7 of 8 resected heart valves. This comprised 13 bacterial genera and 16 species. In addition to 11 pathogens already described as being IE related, 5 bacterial species were identified as having a novel association. In contrast, valve and blood culture-based diagnosis revealed only 4 species from 3 bacterial genera and did not show any relevant antibiotic resistance. The antibiotics chosen on this basis for treatment, however, did not cover the bacterial spectra identified by our amplicon sequencing analysis in 4 of 8 cases. In addition to intramural distribution patterns of infective bacteria, intracellular localization with evidence of bacterial immune escape mechanisms was identified.The high frequency of polymicrobial infections, pathogen diversity, and intracellular persistence of common IE-causing bacteria may provide clues to help explain the persistent and devastating mortality rate observed for IE. Improved bacterial diagnosis by 16S rDNA NGS that increases the ability to tailor antibiotic

  8. New insights into valve-related intramural and intracellular bacterial diversity in infective endocarditis

    Science.gov (United States)

    Feder, Stefan; Lehmann, Stefanie; Kullnick, Yvonne; Buschmann, Tilo; Blumert, Conny; Horn, Friedemann; Neuhaus, Jochen; Neujahr, Ralph; Bagaev, Erik; Hagl, Christian; Pichlmaier, Maximilian; Rodloff, Arne Christian; Gräber, Sandra; Kirsch, Katharina; Sandri, Marcus; Kumbhari, Vivek; Behzadi, Armirhossein; Behzadi, Amirali; Correia, Joao Carlos; Mohr, Friedrich Wilhelm

    2017-01-01

    Aims In infective endocarditis (IE), a severe inflammatory disease of the endocardium with an unchanged incidence and mortality rate over the past decades, only 1% of the cases have been described as polymicrobial infections based on microbiological approaches. The aim of this study was to identify potential biodiversity of bacterial species from infected native and prosthetic valves. Furthermore, we compared the ultrastructural micro-environments to detect the localization and distribution patterns of pathogens in IE. Material and methods Using next-generation sequencing (NGS) of 16S rDNA, which allows analysis of the entire bacterial community within a single sample, we investigated the biodiversity of infectious bacterial species from resected native and prosthetic valves in a clinical cohort of 8 IE patients. Furthermore, we investigated the ultrastructural infected valve micro-environment by focused ion beam scanning electron microscopy (FIB-SEM). Results Biodiversity was detected in 7 of 8 resected heart valves. This comprised 13 bacterial genera and 16 species. In addition to 11 pathogens already described as being IE related, 5 bacterial species were identified as having a novel association. In contrast, valve and blood culture-based diagnosis revealed only 4 species from 3 bacterial genera and did not show any relevant antibiotic resistance. The antibiotics chosen on this basis for treatment, however, did not cover the bacterial spectra identified by our amplicon sequencing analysis in 4 of 8 cases. In addition to intramural distribution patterns of infective bacteria, intracellular localization with evidence of bacterial immune escape mechanisms was identified. Conclusion The high frequency of polymicrobial infections, pathogen diversity, and intracellular persistence of common IE-causing bacteria may provide clues to help explain the persistent and devastating mortality rate observed for IE. Improved bacterial diagnosis by 16S rDNA NGS that increases the

  9. A discussion of system reliability and the relative importance of pumps and valves to overall system availability

    Energy Technology Data Exchange (ETDEWEB)

    Poole, A.B. [Oak Ridge National Lab., TN (United States)

    1996-12-01

    An analysis was undertaken to establish preliminary trends for how component aging can effect failure rates for swing check valves, centrifugal pumps and motor operated valves. These failure rate trends were evaluated over time and linear aging rate models established. The failure rate models were then used with classic reliability theories to estimate reliability as a function of operating time. Reliability theory was also used to establish a simple system reliability model. Using the system model, the relative importance of pumps and valves to the overall system reliability were studied. Conclusions were established relative to overall system availability over time and the relative unavailabilities of the various components studied.

  10. Surgical Management of Percutaneous Transfemoral Access to Minimize Vascular Complications Related to Transcatheter Aortic Valve' Implantation.

    Science.gov (United States)

    Lareyre, Fabien; Raffort, Juliette; Dommerc, Carine; Habib, Yacoub; Bourlon, François; Mialhe, Claude

    2018-02-01

    Transcatheter aortic valve implantation (TAVI) is associated with substantial rates of vascular complications. The aim of our study is to describe the surgical management of percutaneous transfemoral access by a vascular surgeon and to report the 30-day postoperative vascular complications and mortality. Perioperative procedures to manage the femoral access site were recorded retrospectively from 220 consecutive patients who underwent TAVI. Postoperative vascular complications related to the main access were categorized according to the Valve Academic Research Consortium 2 classification. Perioperative procedures related to vascular access were performed for 56 (25.4%) patients: 6 patients required open surgical repair, 48 patients underwent endovascular stenting, and 2 patients had both procedures. The all-cause mortality was 3.6%, but no death related to a vascular complication was reported during the 30-day postoperative follow-up period. Ten (4.5%) patients developed postoperative hematomas; 2 (0.9%) of them were retroperitoneal and led to major bleeding requiring an unplanned surgical intervention. Our study underlines the utility of a multidisciplinary approach to manage the percutaneous access in TAVI for managing postoperative vascular complications.

  11. Evaluation of thrombogenicity of beta-propiolactone/ultraviolet (beta-PL/UV) treated PPSB in chimpanzees

    Energy Technology Data Exchange (ETDEWEB)

    Kotitschke, R.; Stephan, W.; Prince, A.M.; Brotman, B.

    1983-05-01

    The thrombogenicity of beta-PL/UV-treated PPSB (factor IX concentrate) was evaluated in chimpanzees. PPSB isolated from beta-propiolactone-treated and UV-irradiated plasma was injected into chimpanzees at a dose of approximately 100 units/kg body weight. An FDA licensed PPSB preparation served as the negative control, and a preparation containing activated as well as precursor clotting factors served as the positive control. 15 minutes, 1 h, 4 h, and 24 h after the PPSB application the following parameters were determined in the chimpanzee blood: factors II, VII, IX, X, VIII, fibrinogen, AT III, thrombin coagulase, Quick value, APTT and platelet count. Neither the untreated control preparation, nor the PPSB isolated from beta-propiolactone-treated and UV-irradiated plasma, showed signs of thrombogenicity in the chimpanzee model. The positive control indicated that the chimpanzee is a suitable model for the thrombogenicity testing of activated clotting factors.

  12. 30 CFR 250.807 - Additional requirements for subsurface safety valves and related equipment installed in high...

    Science.gov (United States)

    2010-07-01

    ... valves and related equipment installed in high pressure high temperature (HPHT) environments. 250.807... GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Production Safety Systems § 250... pressure high temperature (HPHT) environments. (a) If you plan to install SSSVs and related equipment in an...

  13. Relation of Aortic Valve Morphologic Characteristics to Aortic Valve Insufficiency and Residual Stenosis in Children With Congenital Aortic Stenosis Undergoing Balloon Valvuloplasty.

    Science.gov (United States)

    Petit, Christopher J; Gao, Kevin; Goldstein, Bryan H; Lang, Sean M; Gillespie, Scott E; Kim, Sung-In H; Sachdeva, Ritu

    2016-03-15

    Aortic valve morphology has been invoked as intrinsic to outcomes of balloon aortic valvuloplasty (BAV) for congenital aortic valve stenosis. We sought to use aortic valve morphologic features to discriminate between valves that respond favorably or unfavorably to BAV, using aortic insufficiency (AI) as the primary outcome. All patients who underwent BAV at 2 large-volume pediatric centers from 2007 to 2014 were reviewed. Morphologic features assessed on pre-BAV echo included valve pattern (unicuspid, functional bicuspid, and true bicuspid), leaflet fusion length, leaflet excursion angle, and aortic valve opening area and on post-BAV echo included leaflet versus commissural tear. Primary end point was increase in AI (AI+) of ≥2°. Eighty-nine patients (median age 0.2 years) were included in the study (39 unicuspid, 41 functional bicuspid, and 9 true bicuspid valves). Unicuspid valves had a lower opening area (p <0.01) and greater fusion length (p = 0.01) compared with functional and true bicuspid valves. Valve gradient pre-BAV and post-BAV were not different among valve patterns. Of the 16 patients (18%) with AI+, 14 had leaflet tears (odds ratio 13.9, 3.8 to 50). True bicuspid valves had the highest rate (33%) of AI+. On multivariate analysis, leaflet tears were associated with AI+, with larger opening area pre-BAV and lower fusion length pre-BAV. AI+ was associated with larger pre-BAV opening area. Gradient relief was associated with reduced angle of excursion. Valve morphology influences outcomes after BAV. Valves with lesser fusion and larger valve openings have higher rates of leaflet tears which in turn are associated with AI. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Micro-RNA-126 Reduces the Blood Thrombogenicity in Diabetes Mellitus via Targeting of Tissue Factor.

    Science.gov (United States)

    Witkowski, Marco; Weithauser, Alice; Tabaraie, Termeh; Steffens, Daniel; Kränkel, Nicolle; Witkowski, Mario; Stratmann, Bernd; Tschoepe, Diethelm; Landmesser, Ulf; Rauch-Kroehnert, Ursula

    2016-06-01

    Diabetes mellitus involves vascular inflammatory processes and is a main contributor to cardiovascular mortality. Notably, heightened levels of circulating tissue factor (TF) account for the increased thrombogenicity and put those patients at risk for thromboembolic events. Here, we sought to investigate the role of micro-RNA (miR)-driven TF expression and thrombogenicity in diabetes mellitus. Plasma samples of patients with diabetes mellitus were analyzed for TF protein and activity as well as miR-126 expression before and after optimization of the antidiabetic treatment. We found low miR-126 levels to be associated with markedly increased TF protein and TF-mediated thrombogenicity. Reduced miR-126 expression was accompanied by increased vascular inflammation as evident from the levels of vascular adhesion molecule-1 and fibrinogen, as well as leukocyte counts. With optimization of the antidiabetic treatment miR-126 levels increased and thrombogenicity was reduced. Using a luciferase reporter system, we demonstrated miR-126 to directly bind to the F3-3'-untranslated region, thereby reducing TF expression both on mRNA and on protein levels in human microvascular endothelial cells as well as TF mRNA and activity in monocytes. Circulating miR-126 exhibits antithrombotic properties via regulating post-transcriptional TF expression, thereby impacting the hemostatic balance of the vasculature in diabetes mellitus. © 2016 The Authors.

  15. Mitral valve repair-related hemolysis: a report of two cases

    NARCIS (Netherlands)

    Bruinsma, G. J. B. B.; Bredee, J. J.; de Mol, B. A. J. M.

    1997-01-01

    Two patients are described who suffered from progressive intravascular hemolysis following different kinds of reconstructive surgery of the mitral valve. Within the context of increasing numbers of operations aimed to preserve the mitral valve, the importance and difficulty of prompt recognition and

  16. Proof-of-Concept Evaluation of the SailValve Self-Expanding Deep Venous Valve System in a Porcine Model.

    Science.gov (United States)

    Boersma, Doeke; Vink, Aryan; Moll, Frans L; de Borst, Gert J

    2017-06-01

    To evaluate the SailValve, a new self-expanding deep venous valve concept based on a single polytetrafluoroethylene cusp floating up and down in the bloodstream like a sail, acting as a flow regulator and allowing minimal reflux to reduce thrombogenicity. Both iliac veins of 5 pigs were implanted with SailValve devices; the first animal was an acute pilot experiment to show the feasibility of accurately positioning the SailValve via a femoral access. The other 4 animals were followed for 2 weeks (n=2) or 4 weeks (n=2) under a chronic implantation protocol. Patency and valve function were evaluated directly in all animals using ascending and descending phlebography after device placement and at termination in the chronic implant animals. For reasons of clinical relevance, a regimen of clopidogrel and calcium carbasalate was administered. Histological analysis was performed according to a predefined protocol by an independent pathologist. Deployment was technically feasible in all 10 iliac veins, and all were patent directly after placement. No perioperative or postoperative complications occurred. Ascending phlebograms in the follow-up animals confirmed the patency of all valves after 2 or 4 weeks. Descending phlebograms showed full function in 5 of 8 valves. Limited reflux was seen in 1 valve (4-week group), and the function in the remaining 2 valves (2-week group) was insufficient because of malpositioning. No macroscopic thrombosis was noted on histology. Histology in the follow-up groups revealed a progressive inflammatory reaction to the valves. This animal study shows the potential of the SailValve concept with sufficient valve function after adequate positioning and no (thrombogenic) occlusions after short-term follow-up. Future research is essential to optimize valve material and long-term patency.

  17. Experimental Investigation of Flow trough a Mechanical Heart Valve

    Science.gov (United States)

    Haji-Esmaeili, Farida; Oshkai, Peter

    2006-11-01

    Turbulent flow trough a model of a mechanical heart valve is investigated using digital particle image velocimetry. The valve leaflets are represented by flat plates mounted in a duct. The emphasis is on the effect of the valve design on the platelet activation state associated with the resulting flow field. Global quantitative images corresponding to multiple planes of data acquisition provide insight into the three-dimensional nature of the flow. Turbulent flow structures including jet-like regions and shed vortices are characterized in terms of patterns of instantaneous and time-averaged velocity, vorticity, and streamline topology. Potential of bileaflet heart valves for being thrombogenic is assessed by quantitative comparison of the associated flow fields in terms of maximum values of turbulent stresses and platelet activation states.

  18. Noninvasive assessment of filling pressure and left atrial pressure overload in severe aortic valve stenosis: relation to ventricular remodeling and clinical outcome after aortic valve replacement

    DEFF Research Database (Denmark)

    Dahl, Jordi S; Videbæk, Lars; Poulsen, Mikael K

    2011-01-01

    One of the hemodynamic consequences of aortic valve stenosis is pressure overload leading to left atrial dilatation. Left atrial size is a known risk factor providing prognostic information in several cardiac conditions. It is not known if this is also the case in patients with aortic valve...

  19. Valve Disease

    Science.gov (United States)

    ... See also on this site: Diseases of the Mitral Valve Diseases of the Aortic Valve Diseases of the Tricuspid ... most invasive option for the treatment of valve disease. During surgery, ... defects of the mitral valve. Replacement is used to treat any diseased ...

  20. Anticoagulation dilemma in a high-risk patient with On-X valves

    Directory of Open Access Journals (Sweden)

    Ami M Karkar

    2015-01-01

    Full Text Available Thromboembolism continues to be a major concern in patients with mechanical heart valves, especially in those with unsatisfactory anticoagulation levels. The new On-X valve (On-X Life Technologies, Austin, TX, USA has been reported as having unique structural characteristics that offer lower thrombogenicity to the valve. We report a case where the patient received no or minimal systemic anticoagulation after placement of On-X mitral and aortic valves due to development of severe mucosal arterio-venous malformations yet did not show any evidence of thromboembolism. This case report reinforces the findings of recent studies that lower anticoagulation levels may be acceptable in patients with On-X valves and suggests this valve may be particularly useful in those in whom therapeutic levels of anticoagulation cannot be achieved due to increased risk of bleeding.

  1. Patient outcome after aortic valve replacement with a mechanical or biological prosthesis: weighing lifetime anticoagulant-related event risk against reoperation risk.

    Science.gov (United States)

    van Geldorp, Martijn W A; Eric Jamieson, W R; Kappetein, A Pieter; Ye, Jian; Fradet, Guy J; Eijkemans, Marinus J C; Grunkemeier, Gary L; Bogers, Ad J J C; Takkenberg, Johanna J M

    2009-04-01

    Although the results of aortic valve replacement with different valve prostheses are well documented in terms of survival, the risks of (valve-related) events are less well explored. We used a dataset of 3934 patients who underwent aortic valve replacement with either a bioprosthesis (73%) or a mechanical prosthesis (27%) between 1982 and 2003 to simulate the outcome of patients after aortic valve replacement with either valve type. With the use of microsimulation, we compared total age and gender-specific life expectancy, event-free life expectancy, reoperation-free life expectancy, lifetime risks of reoperation, and valve-related events for both valve types. The total follow-up was 26,467 patient-years. The mean follow-up was 6.1 years in the biological arm and 8.5 years in the mechanical arm. The mean age at implantation was 70 and 58 years for biological and mechanical prostheses, respectively, and the percentage of concomitant coronary artery bypass grafting was 47% and 28%, respectively. For a 60-year-old man, simulated life expectancy in years for biological versus mechanical prostheses was 11.9 versus 12.2, event-free life expectancy was 9.8 versus 9.3, and reoperation-free life expectancy was 10.5 versus 11.9. Lifetime risk of reoperation was 25% versus 3%. Lifetime risk of bleeding was 12% versus 41%. Even for patients aged 60 years, event-free life expectancy is better with a bioprosthesis. Although the chance of reoperation is higher, the lifetime risk of bleeding is lower compared with a mechanical prosthesis. Comparing lifetime event risks between different types of valve prostheses provides more insight into patient outcome after aortic valve replacement and aids patient selection and counseling.

  2. Mechanical prosthetic valve disease is related with an increase in depression and anxiety disorder.

    Science.gov (United States)

    Turker, Yasemin; Ongel, Kurtulus; Ozaydin, Mehmet; Turker, Yasin; Yildirim Bas, Funda; Akkaya, Mehmet

    2015-02-01

    Patients with organic disease can present with psychiatric symptoms. We hypothesized that since patients with prosthetic heart valve require frequent hospital followup and are at higher risk for complications, the incidence of depression and anxiety is higher in these patients. This cross-sectional study prospectively studied 98 consecutive patients with mechanical prosthetic heart valve. All patients fulfilled prosthetic heart valve evaluation form, Beck Depression Inventory (BDI) and Hamilton Anxiety Scale (HAS). Complete blood count, basic metabolic panel and echocardiogram results were collected for all the patients. Using the BDI, there were 26 patients (27%) with no depression, 20 (20%) with mild depression, 38 (39%) with moderate, 4 (4%) with severe and 10 (10%) patients with very severe depression. Avarege score was 18.3±11.4 on BDI and 19.1±11.1 on HAS. The depression level was positively associated with prothrombin time (p les than 0.001) and international normalized ratio (INR) level (p les than 0.001). Hamilton Anxiety Scale was significantly correlated with comorbidities (r: 0.344; p=0.002), blood transfusion (r: 0.370; p les than 0.001), obesity (r: 0.319; p=0.007) and Beck Depression Scale was correlated with comorbidities (r: 0.328; p=0.002), in patients with prosthetic heart valve disease. Patients with prosthetic heart valve have higher prevalence of depression and higher scores of anxiety and depression. Early recognition and appropriate treatment of depression and anxiety may decrease the morbidity in prosthetic heart valve disease. Besides, use of new oral anticoagulant agents that do not need INR check, could decrease anxiety and depression in the future.

  3. Mechanical prosthetic valve disease is related with an increase in depression and anxiety disorder

    Directory of Open Access Journals (Sweden)

    Yasemin Turker

    2015-02-01

    Full Text Available Aim Patients with organic disease can present with psychiatric symptoms. We hypothesized that since patients with prosthetic heart valve require frequent hospital followup and are at higher risk for complications, the incidence of depression and anxiety is higher in these patients. Methods This cross-sectional study prospectively studied 98 consecutive patients with mechanical prosthetic heart valve. All patients fulfilled prosthetic heart valve evaluation form, Beck Depression Inventory (BDI and Hamilton Anxiety Scale (HAS. Complete blood count, basic metabolic panel and echocardiogram results were collected for all the patients. Results Using the BDI, there were 26 patients (27% with no depression, 20 (20% with mild depression, 38 (39% with moderate, 4 (4% with severe and 10 (10% patients with very severe depression. Avarege score was 18.3±11.4 on BDI and 19.1±11.1 on HAS. The depression level was positively associated with prothrombin time (p<0.001 and international normalized ratio (INR level (p<0.001. Hamilton Anxiety Scale was significantly correlated with comorbidities (r: 0.344; p=0.002, blood transfusion (r: 0.370; p<0.001, obesity (r: 0.319; p=0.007 and Beck Depression Scale was correlated with comorbidities (r: 0.328; p=0.002, in patients with prosthetic heart valve disease. Conlusion Patients with prosthetic heart valve have higher prevalence of depression and higher scores of anxiety and depression. Early recognition and appropriate treatment of depression and anxiety may decrease the morbidity in prosthetic heart valve disease. Besides, use of new oral anticoagulant agents that do not need INR check, could decrease anxiety and depression in the future.

  4. Three-Dimensional Mitral Valve Morphology and Age-Related Trends in Children and Young Adults with Structurally Normal Hearts Using Transthoracic Echocardiography.

    Science.gov (United States)

    Jolley, Matthew A; Ghelani, Sunil J; Adar, Adi; Harrild, David M

    2017-06-01

    The mitral valve has a complex three-dimensional (3D) morphology that is incompletely described by two-dimensional echocardiography (echo). Three-dimensional echo provides a more robust tool to analyze the mitral valve. The shape of the mitral annulus and leaflets, and differences with age, have not been described by 3D echo in normal children. Our objective was to characterize and quantify the 3D mitral valve morphology in children with normal transthoracic echocardiograms over a broad spectrum of age and to identify differences in valve shape with age. Three-dimensional midsystolic mitral valve models were constructed in 100 children and young adults with normal echocardiograms using 3D transthoracic images. Annular and leaflet metrics were quantified and regression equations were prepared. Interuser and intrauser variability was measured. Two hundred fifty patients, from neonate to young adult, were retrospectively reviewed to obtain 100 evaluable patients (40% evaluable). The annular height to commissural width ratio of the mitral valve ("saddle shape") was preserved across age (median 24.3, IQR 21.8-28.1). Three-dimensional mitral valve area, length, and volume parameters were linearly related to body surface area (P  0.87, P mitral valve morphology in children is possible in a modern clinical pediatric echocardiography laboratory using transthoracic images, although further optimization of imaging is needed. The saddle shape of the mitral annulus was preserved across age and size. Most mitral valve parameters increased linearly with patient size. Further investigation is warranted to explore changes in valve morphology in the pediatric population in health and with disease. Copyright © 2017 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

  5. Long-term tricuspid valve prosthesis-related complications in patients with congenital heart disease

    NARCIS (Netherlands)

    van Slooten, Ymkje J.; Freling, Hendrik G.; van Melle, Joost P.; Mulder, Barbara J. M.; Jongbloed, Monique R. M.; Ebels, Tjark; Voors, Adriaan A.; Pieper, Petronella G.

    OBJECTIVES: In patients with acquired valvar disease, morbidity and mortality rates after tricuspid valve replacement (TVR) are high. However, in adult patients with congenital heart disease, though data concerning outcome after TVR are scarce, even poorer results are suggested in patients with

  6. Modeling the Mitral Valve

    Science.gov (United States)

    Kaiser, Alexander

    2016-11-01

    The mitral valve is one of four valves in the human heart. The valve opens to allow oxygenated blood from the lungs to fill the left ventricle, and closes when the ventricle contracts to prevent backflow. The valve is composed of two fibrous leaflets which hang from a ring. These leaflets are supported like a parachute by a system of strings called chordae tendineae. In this talk, I will describe a new computational model of the mitral valve. To generate geometry, general information comes from classical anatomy texts and the author's dissection of porcine hearts. An MRI image of a human heart is used to locate the tips of the papillary muscles, which anchor the chordae tendineae, in relation to the mitral ring. The initial configurations of the valve leaflets and chordae tendineae are found by solving solving an equilibrium elasticity problem. The valve is then simulated in fluid (blood) using the immersed boundary method over multiple heart cycles in a model valve tester. We aim to identify features and mechanisms that influence or control valve function. Support from National Science Foundation, Graduate Research Fellowship Program, Grant DGE 1342536.

  7. Relation of Mitral Valve Surgery Volume to Repair Rate, Durability, and Survival.

    Science.gov (United States)

    Chikwe, Joanna; Toyoda, Nana; Anyanwu, Anelechi C; Itagaki, Shinobu; Egorova, Natalia N; Boateng, Percy; El-Eshmawi, Ahmed; Adams, David H

    2017-04-24

    Degenerative mitral valve repair rates remain highly variable, despite established benefits of repair over replacement. The contribution of surgeon-specific factors is poorly defined. This study evaluated the influence of surgeon case volume on degenerative mitral valve repair rates and outcomes. A mandatory New York State database was queried and 5,475 patients were identified with degenerative mitral disease who underwent mitral valve operations between 2002 and 2013. Mitral repair rates, mitral reoperations within 12 months of repair, and survival were analyzed using multivariable Cox modeling and restricted cubic spline function. Median annual surgeon volume of any mitral operations was 10 (range 1 to 230), with a mean repair rate of 55% (n = 20,797 of 38,128). In the subgroup of patients with degenerative disease, the mean repair rate was 67% (n = 3,660 of 5,475), with a range of 0% to 100%. Mean repair rates ranged from 48% (n = 179 of 370) for surgeons with total annual volumes of ≤10 mitral operations to 77% (n = 1,710 of 2,216) for surgeons with total annual volumes of >50 mitral operations (p mitral valve disease (adjusted odds ratio [OR]: 1.13 for every additional 10 mitral operations; 95% confidence interval [CI]: 1.10 to 1.17; p mitral operations annually; and improved 1-year survival (adjusted hazard ratio: 0.95 for every additional 10 operations; 95% CI: 0.92 to 0.98; p = 0.001). For surgeons with a total annual volume of ≤25 mitral operations, repair rates were higher (63.8%; n = 180 of 282) if they operated in the same institution as a surgeon with total annual mitral volumes of >50 and degenerative mitral valve repair rates of >70%, compared with surgeons operating in the other institutions (51.3%; n = 580 of 1,130) (adjusted OR: 1.79; 95% CI: 1.24 to 2.60; p mitral repair rates, but also freedom from reoperation, and survival. The data from this study support the guideline's concept of reference referral to experienced mitral

  8. Validation of a voice prosthesis questionnaire to assess valved speech and its related issues in patients following total laryngectomy.

    Science.gov (United States)

    Kazi, R; Singh, A; De Cordova, J; Al-Mutairy, A; Clarke, P; Nutting, C; Rhys-Evans, P; Harrington, K

    2006-10-01

    To establish the reliability and validity of a new self-administered questionnaire to assess valved speech and its related issues in patients who have undergone a total laryngectomy operation. Cross-sectional psychometric validation study. Tertiary cancer care centre. We identified sixty-one total laryngectomy patients with no sign of recurrent disease and using voice prosthesis from the speech and language therapy database of the Royal Marsden Hospital. The patients were assessed using a postal self-administered voice prosthesis questionnaire concerning the voice valve and it's related issues. Patients were also asked to complete the University of Michigan voice related quality of life and University of Washington head and neck quality of life (version 4) questionnaires. Test-retest and internal consistency reliability; content; criterion and construct validity. We received completed questionnaires from fifty-one of the sixty-one total laryngectomy patients identified for the study providing a response rate of 84%. The median age of the group was 65 years (range: 40-85) with thirty-seven males and fourteen females. The internal consistency reliability using the Cronbach's alpha coefficient was 0.87 (range: 0.85 to 0.89). Test-retest reliability showed that more than 75% of patients had a score on re-test that was within 1 point of their original score. Content validity was ensured during the design process. The median Spearman correlation coefficient was 0.25 for convergent construct validity with the University of Washington head and neck quality of life questionnaire and 0.64 for criterion validity on comparison with the University of Michigan voice related quality of life scale. The voice prosthesis questionnaire is the first validated and reliable self-administered questionnaire designed specifically for evaluating valved speech and its related issues in patients who have undergone total laryngectomy. The voice prosthesis questionnaire has significant utility

  9. Heart valve surgery

    Science.gov (United States)

    Valve replacement; Valve repair; Heart valve prosthesis; Mechanical valves; Prosthetic valves ... can relieve your symptoms and prolong your life. Mechanical heart valves do not often fail. However, blood clots can ...

  10. Impact of recipient-related factors on structural dysfunction of xenoaortic bioprosthetic heart valves

    Directory of Open Access Journals (Sweden)

    Barbarash O

    2015-03-01

    Full Text Available Olga Barbarash, Natalya Rutkovskaya, Oksana Hryachkova, Olga Gruzdeva, Evgenya Uchasova, Anastasia Ponasenko, Natalya Kondyukova, Yuri Odarenko, Leonid Barbarash Federal State Budgetary Scientific Institution Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, Russia Objective: To analyze the influence of recipient-related metabolic factors on the rate of structural dysfunction caused by the calcification of xenoaortic bioprostheses. Materials and methods: We retrospectively analyzed clinical status, calcium–phosphorus metabolism, and nonspecific markers of inflammatory response in bioprosthetic mitral valve recipients with calcific degeneration confirmed by histological and electron microscopic studies (group 1, n=22, and in those without degeneration (group 2, n=48. Results: Patients with confirmed calcification of bioprostheses were more likely to have a severe clinical state (functional class IV in 36% in group 1 versus 15% in group 2, P=0.03 and a longer cardiopulmonary bypass period (112.8±18.8 minutes in group 1 versus 97.2±23.6 minutes in group 2, P=0.02 during primary surgery. Patients in group 1 demonstrated moderate hypovitaminosis D (median 34.0, interquartile range [21.0; 49.4] vs 40 [27.2; 54.0] pmol/L, P>0.05, osteoprotegerin deficiency (82.5 [44.2; 115.4] vs 113.5 [65.7; 191.3] pg/mL, P>0.05 and osteopontin deficiency (4.5 [3.3; 7.7] vs 5.2 [4.1; 7.2] ng/mL, P>0.05, and significantly reduced bone-specific alkaline phosphatase isoenzyme (17.1 [12.2; 21.4] vs 22.3 [15.5; 30.5] U/L, P=0.01 and interleukin-8 levels (9.74 [9.19; 10.09] pg/mL vs 13.17 [9.72; 23.1] pg/mL, P=0.045 compared with group 2, with an overall increase in serum levels of proinflammatory markers. Conclusion: Possible predictors of the rate of calcific degeneration of bioprostheses include the degree of decompensated heart failure, the duration and invasiveness of surgery, and the characteristics of calcium–phosphorus homeostasis in

  11. Engineering and maintenance applied to safety-related valves in nuclear power plants; Ingenieria y mantenimiento aplicado a valvulas relacionadas con la seguridad en centrales nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Verdu, M. F.; Perez-Aranda, J.

    2014-04-01

    Nuclear Division in Iberdrola engineering and Construction has a team with extensive experience on engineering and services works related to valves. Also, this team is linked to UNESA as Technical support and Reference Center. Iberdrola engineering and construction experience in nuclear power plants valves, gives effective response to engineering and maintenance works that can be demanded in a nuclear power plant and it requires a high degree of qualification and knowledge both in Operation and Outages. (Author)

  12. AFM study of the thrombogenicity of carbon-based coatings for cardiovascular applications

    Energy Technology Data Exchange (ETDEWEB)

    Karagkiozaki, V. [Department of Physics, Laboratory for Thin Films-Nanosystems and Nanometrology (LTFN), Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece); AHEPA Hospital, 1st Cardiology Department, Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece); Logothetidis, S. [Department of Physics, Laboratory for Thin Films-Nanosystems and Nanometrology (LTFN), Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece)], E-mail: logot@auth.gr; Laskarakis, A. [Department of Physics, Laboratory for Thin Films-Nanosystems and Nanometrology (LTFN), Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece); Giannoglou, G. [AHEPA Hospital, 1st Cardiology Department, Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece); Lousinian, S. [Department of Physics, Laboratory for Thin Films-Nanosystems and Nanometrology (LTFN), Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece)

    2008-08-25

    The new nanotechnologies in biomaterials for cardiovascular applications target at surface alterations for prevention of platelets aggregation and subsequent clotting as their usual failure arises from thrombogenicity. Knowledge of structural properties of platelets during their adhesion on nanostructure materials is required to obtain a comprehensive understanding of their activation and the conventional imaging tools require special preparation of the samples and does not guarantee the viability of the cells. Thus, in this study, the atomic force microscope (AFM) which is a non-destructive and nanoscale precision technique is implemented for the study of platelets' adhesion onto amorphous hydrogenated carbon (a-C:H) thin films and a methodology is developed. Carbon-based thin films grown by magnetron sputtering under different deposition conditions are considered to meet the requirements for biomedical applications and were selected as well-characterized, case study materials. Platelet rich plasma drawn from healthy donors was used for the study of platelets adhesion onto the a-C:H films. The fourier transform IR phase modulated spectroscopic ellipsometry (FTIRSE) (900-3500 cm{sup -1}) being a powerful, non-destructive, optical technique was used for the investigation of bonding structure of the adherent platelets onto the a-C:H materials and the contribution of the different vibration bands of the platelet bonding groups was shown and discussed. The effect of nanostructure, surface properties and wettability of the carbon thin films on their thrombogenic potential was verified and it was found that the different deposition conditions determine their structural, surface and biological properties. Thus, the tailoring of surface properties of biomaterials and the informative study of platelets-nanomaterials interactions with AFM and FTIRSE will revolutionize the development of less thrombogenic biomaterials.

  13. Quantitation of thrombogenicity of hemodialyzer with technetium-99m and indium-111 labeled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Dewanjee, M.K.; Kapadvanjwala, Mansoor; Ruzius, Kees; Serafini, A.N.; Zilleruelo, G.E.; Sfakianakis, G.N. (Miami Univ., FL (United States). School of Medicine Althin CD-Medical Inc., Miami Lakes, FL (United States))

    1993-07-01

    The platelet thromobogenicity of a hemodialyzer was quantified with [sup 99m]Tc- and [sup 111]In-labeled platelets. The platelets collected from blood of Beagle dogs, Yorkshire pigs and human volunteers were labeled with [sup 111]in-tropolone (detergent-free) and [sup 99m]Tc-HMPAO. Hemodialysis was performed with a hollow-fiber dialyzer (HFD) in a flow-loop, the temperature of which was maintained at 37[sup o]C, with flow-rates of 7, 150 and 270 mL/min; after dialysis, the HFD radioactivity was measured with an ionization chamber and imaged with a [gamma]-camera. The radioactivity of samples of hollow-fibers taken from the top, middle and bottom of the dialyzer was determined with a [gamma]-counter. The mean values of hemodialyzer-adherent platelet radioactivity were calculated for both radionuclides. The canine platelets were found to be more thrombogenic than porcine and human platelets. The adhesivity of porcine platelets to the biomaterial (cellulose-acetate) of the dialyzer approximated that of human platelets. The [sup 99m]Tc label underestimated the thrombus formation (P < 0.01 ). The dynamic processes of thrombosis and embolization from the hemodialyzer resulted in the large standard deviations around the mean values of the adherent thrombus. In spite of this limitation of the dynamic pathology, the quantitation of comparative throbogenicity with [sup 111]In- and [sup 99m]Tc-labeled platelets suggests that both radionuclides could be used for measurement of device-induced thrombogenicity and may provide an estimation of prosthesis-induced thrombogenicity of human platelets from animal studies. (Author).

  14. Polymeric trileaflet prosthetic heart valves: evolution and path to clinical reality

    Science.gov (United States)

    Claiborne, Thomas E; Slepian, Marvin J; Hossainy, Syed; Bluestein, Danny

    2013-01-01

    Present prosthetic heart valves, while hemodynamically effective, remain limited by progressive structural deterioration of tissue valves or the burden of chronic anticoagulation for mechanical valves. An idealized valve prosthesis would eliminate these limitations. Polymeric heart valves (PHVs), fabricated from advanced polymeric materials, offer the potential of durability and hemocompatibility. Unfortunately, the clinical realization of PHVs to date has been hampered by findings of in vivo calcification, degradation and thrombosis. Here, the authors review the evolution of PHVs, evaluate the state of the art of this technology and propose a pathway towards clinical reality. In particular, the authors discuss the development of a novel aortic PHV that may be deployed via transcatheter implantation, as well as its optimization via device thrombogenicity emulation. PMID:23249154

  15. [Dynamics of morphometric parameters of peripheral blood platelets as a criterion in assessing thrombogenicity of dialysis membranes].

    Science.gov (United States)

    Vlasova, E A; Vasilenko, I A; Suslov, V P; Pashkin, I N

    2011-01-01

    The study enrolled 45 patients with terminal chronic renal failure (CRF) aged 24-57 years on hemodialysis (a study group) and 30 healthy subjects of matched age (a control group). Morphofunctional condition of circulating platelets in situ was assessed by vital computer morphometry using computer phase-interference microscope, the analysis was made of opticogeometric parameters and morphological features of live platelets reflecting the degree of their activation. CRF patients' proportion of different platelet types in circulating population was 56.5, 34, 8.7 and 0.8% (platelets in situ, platelets with low, high activation, degenerative) versus 59.4, 28.1, 10.5 and 2% in the controls, respectively. Changes in morphological composition and opticogeometric parameters of circulating platelets were found in the dialysis membrane after a hemodialysis procedure. The changes were less or more pronounced depending on the dialysis membrane type. Thus, vital morphometric platelet parameters reflect condition of the platelets allowing quantitative assessment of impairment of the structure and functional activity of the cells in CRF progression. Hemodialysis procedure results in characteristic alterations of morphofunctional status of circulating platelets related, to a certain degree, to the material of extracorporeal outline. This dictates necessity of objective evaluation of such impact and prognosis of thrombogenic complications. Morphometric parameters of platelets can serve objective criteria of dialysis membrane thromboginicity.

  16. Development and hemocompatibility testing of nitric oxide releasing polymers using a rabbit model of thrombogenicity.

    Science.gov (United States)

    Major, Terry C; Handa, Hitesh; Annich, Gail M; Bartlett, Robert H

    2014-10-01

    Hemocompatibility is the goal for any biomaterial contained in extracorporeal life supporting medical devices. The hallmarks for hemocompatibility include nonthrombogenicity, platelet preservation, and maintained platelet function. Both in vitro and in vivo assays testing for compatibility of the blood/biomaterial interface have been used over the last several decades to ascertain if the biomaterial used in medical tubing and devices will require systemic anticoagulation for viability. Over the last 50 years systemic anticoagulation with heparin has been the gold standard in maintaining effective extracorporeal life supporting. However, the biomaterial that maintains effective ECLS without the use of any systemic anticoagulant has remained elusive. In this review, the in vivo 4-h rabbit thrombogenicity model genesis will be described with emphasis on biomaterials that may require no systemic anticoagulation for extracorporeal life supporting longevity. These novel biomaterials may improve extracorporeal circulation hemocompatibility by preserving near resting physiology of the major blood components, the platelets and monocytes. The rabbit extracorporeal circulation model provides a complete assessment of biomaterial interactions with the intrinsic coagulation players, the circulating platelet and monocytes. This total picture of blood/biomaterial interaction suggests that this rabbit thrombogenicity model could provide a standardization for biomaterial hemocompatibility testing. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  17. Frequency and Effect of Access-Related Vascular Injury and Subsequent Vascular Intervention After Transcatheter Aortic Valve Replacement

    DEFF Research Database (Denmark)

    Dencker, Ditte; Taudorf, Mikkel; Luk, N H Vincent

    2016-01-01

    Vascular access and closure remain a challenge in transcatheter aortic valve replacement (TAVR). This single-center study aimed to report the incidence, predictive factors, and clinical outcomes of access-related vascular injury and subsequent vascular intervention. During a 30-month period, 365...... patients underwent TAVR and 333 patients (94%) were treated by true percutaneous transfemoral approach. Of this latter group, 83 patients (25%) had an access-related vascular injury that was managed by the use of a covered self-expanding stent (n = 49), balloon angioplasty (n = 33), or by surgical...... for access-related vascular intervention. In addition, a high sheath/common femoral artery ratio as measured on preoperative CTA was associated with a higher rate of post-TAVR vascular intervention. The radiation dose, iodine contrast volume, transfusion need, length of hospitalization, and 30-day mortality...

  18. Principal stress analysis in LDA measurement of the flow field downstream of 19-mm Sorin Bicarbon heart valve.

    Science.gov (United States)

    Barbaro, V; Grigioni, M; Daniele, C; D'Avenio, G

    1998-11-01

    Heart valve replacement has become, since many years, a common surgical practice. Along with the improvement that the patients' health has derived from it, however, a certain amount of risk could not be avoided, bound to the inevitable hemodynamic disturbances that an artificial device generates. A major shortcoming, often reported, is the formation of thrombus on the edge of the prosthetic valve, with a possible obstruction of the orifices through which blood should normally flow undisturbed. Hemolysis is another possible consequence of the implantation of a mechanical heart valve, generally correlated to turbulence downstream of prosthetic heart valves (PHV). As it is agreed upon by many researchers, the risk of thrombogenicity or hemolysis is higher in those valves that are more subject to promote turbulence and flow separation in the flow through them. In the following paper, we present a study of the turbulence-related shear stress downstream of a bileaflet valve of minimum size (19 mm external diameter) Sorin Bicarbon. This size was chosen, accordingly to the Food & Drug Administration (FDA) draft guidance suggestion to investigate the worst case in turbulence promoted by PHVs, in order to have the highest velocity gradients and shear stresses for the FDA-stated cardiac output (6 1/min), related to maximum Reynolds number conditions. Velocity data were collected with the two-dimensional laser Doppler anemometry (LDA) technique; whereas this approach does not investigate directly all three components of the flow field, in the present case (bileaflet valves) it is not a limitation to the assessment of the maximum turbulence shear stress (TSS), thanks to the two-dimensional flow nature downstream of bileaflet models. Data taken in coincident mode were elaborated in order to determine the maximum shear stress in the measured points in the flow field, using the 2D Principal Stress Analysis (PSA). The consequences of a variable principal normal stress direction all

  19. Direct measurements of nitric oxide release in relation to expression of endothelial nitric oxide synthase in isolated porcine mitral valves

    DEFF Research Database (Denmark)

    Moesgaard, Sophia Gry; Olsen, Lisbeth Høier; Aasted, Bent

    2007-01-01

    The aim of this study was to measure the direct release of nitric oxide (NO) from the porcine mitral valve using a NO microelectrode. Furthermore, the expression and localization of endothelial nitric oxide synthase (eNOS) in the mitral valve was studied using immunohistochemistry, Western blotti...... techniques for investigations into the role of local NO release in mitral valve diseases.......The aim of this study was to measure the direct release of nitric oxide (NO) from the porcine mitral valve using a NO microelectrode. Furthermore, the expression and localization of endothelial nitric oxide synthase (eNOS) in the mitral valve was studied using immunohistochemistry, Western blotting...... and RT-PCR. Results show that bradykinin increases NO release from mitral valves (¿Bradykinin: 33.71 ± 10.41 nM NO, P

  20. Impact of routine crossover balloon occlusion technique on access-related vascular complications following transfemoral transcatheter aortic valve replacement.

    Science.gov (United States)

    Zaman, Sarah; Gooley, Robert; Cheng, Victoria; McCormick, Liam; Meredith, Ian T

    2016-08-01

    To determine the impact of incorporating routine crossover balloon occlusion technique (CBOT) for vascular access closure following transcatheter aortic valve replacement (TAVR) on major access-site-related complications. Vascular complications are associated with increased mortality following TAVR. The CBOT involves passage of a balloon catheter from the contralateral femoral artery to enable controlled closure of large-sheath access-sites. Consecutive patients who underwent transfemoral TAVR as part of three clinical trials were prospectively recruited. Patients who had routine CBOT (CBOT group, n = 55) were compared to preceding patients who did not undergo CBOT (control group, n = 43). The primary endpoint was 30-day occurrence of access-site-related Valve Academic Research Consortium (VARC)-2 defined major vascular and/or bleeding complications. CBOT was successfully performed in 96% with 2% occurrence of a minor CBOT-related complication. At 30-days access-site-related major vascular and/or bleeding occurred in 5.5% and 18.6% of the CBOT and control group, respectively (P = 0.042). This consisted of VARC-2 major vascular events in 3.6% and 16.3% (P = 0.036) and VARC-2 major/life-threatening bleeding events in 5.5% and 14.0% (P = 0.137) of the CBOT and control group, respectively. Transfusion of ≥2 units of packed red blood cells were required in 10.9% and 30.2% of the CBOT and control group, respectively (P = 0.016). There was no significant difference in contrast load, procedure time, and kidney injury between the two groups. Routine CBOT for TAVR access-site closure has a high success rate and is associated with a significant reduction in VARC-2 major vascular and bleeding complications compared to TAVR performed without CBOT. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  1. Platelet thrombosis in cardiac-valve prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Dewanjee, M.K.

    1989-01-01

    The contribution of platelets and clotting factors in thrombosis on cardiovascular prostheses had been quantified with several tracers. Thrombus formation in vivo could be measured semiquantitatively in animal models and patients with indium-111, Technetium-99m labeled platelets, iodine-123, iodine-131 labeled fibrinogen, and In-111 and Tc-99m labeled antibody to the fibrinogen-receptor on the platelet- membrane, or fibrin. The early studies demonstrated that certain platelet-inhibitors, e.g. sulfinpyrazone, aspirin or aspirin- persantine increased platelet survival time with mechanical valves implanted in the baboon model and patients. Thrombus localization by imaging is possible for large thrombus on thrombogenic surface of prosthesis in the acute phase. The majority of thrombus was found in the sewing ring (Dacron) in the acute phase in both the mechanical and tissue valves. The amount of retained thrombus in both mechanical and tissue valves in our one-day study in the dog model was similar (< 1% if injected In-111 platelets = 5 billion platelets). As the fibrous ingrowth covered the sewing ring, the thrombus formation decreased significantly. Only a small amount of thrombus was found on the leaflets at one month in both the dog and calf models. 38 refs., 9 figs., 5 tabs.

  2. The impact of a new model-based iterative reconstruction algorithm on prosthetic heart valve related artifacts at reduced radiation dose MDCT

    NARCIS (Netherlands)

    Suchá, Dominika; Willemink, Martin J.; de Jong, Pim A.; Schilham, Arnold M. R.; Leiner, Tim; Symersky, Petr; Budde, Ricardo P. J.

    2014-01-01

    To assess the impact of hybrid iterative reconstruction (IR) and novel model-based iterative reconstruction (IMR) and dose reduction on prosthetic heart valve (PHV) related artifacts and objective image quality. One transcatheter and two mechanical PHVs were embedded in diluted contrast-gel,

  3. Frequency and Effect of Access-Related Vascular Injury and Subsequent Vascular Intervention After Transcatheter Aortic Valve Replacement.

    Science.gov (United States)

    Dencker, Ditte; Taudorf, Mikkel; Luk, N H Vincent; Nielsen, Michael B; Kofoed, Klaus F; Schroeder, Torben V; Søndergaard, Lars; Lönn, Lars; De Backer, Ole

    2016-10-15

    Vascular access and closure remain a challenge in transcatheter aortic valve replacement (TAVR). This single-center study aimed to report the incidence, predictive factors, and clinical outcomes of access-related vascular injury and subsequent vascular intervention. During a 30-month period, 365 patients underwent TAVR and 333 patients (94%) were treated by true percutaneous transfemoral approach. Of this latter group, 83 patients (25%) had an access-related vascular injury that was managed by the use of a covered self-expanding stent (n = 49), balloon angioplasty (n = 33), or by surgical intervention (n = 1). In 16 patients (5%), the vascular injury was classified as a major vascular complication. Absence of a preprocedural computed tomography angiography (CTA) of the iliofemoral arteries (OR 2.04, p = 0.007) and female gender (OR 2.18, p = 0.004) were independent predictors of the need for access-related vascular intervention. In addition, a high sheath/common femoral artery ratio as measured on preoperative CTA was associated with a higher rate of post-TAVR vascular intervention. The radiation dose, iodine contrast volume, transfusion need, length of hospitalization, and 30-day mortality were not significantly different between patients with versus without access-related vascular intervention. In conclusion, access-related vascular intervention in patients who underwent transfemoral-TAVR is not uncommon. Female gender and a high sheath/common femoral artery ratio are risk factors for access-related vascular injury, whereas preprocedural planning with CTA of the access vessels may reduce the risk of vascular injury. Importantly, most access-related vascular injuries may be treated by percutaneous techniques with similar clinical outcomes to patients without vascular injuries. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Aortic valve insufficiency in the teenager and young adult: the role of prosthetic valve replacement.

    Science.gov (United States)

    Bradley, Scott M

    2013-10-01

    The contents of this article were presented in the session "Aortic insufficiency in the teenager" at the congenital parallel symposium of the 2013 Society of Thoracic Surgeons (STS) annual meeting. The accompanying articles detail the approaches of aortic valve repair and the Ross procedure.(1,2) The current article focuses on prosthetic valve replacement. For many young patients requiring aortic valve surgery, either aortic valve repair or a Ross procedure provides a good option. The advantages include avoidance of anticoagulation and potential for growth. In other patients, a prosthetic valve is an appropriate alternative. This article discusses the current state of knowledge regarding mechanical and bioprosthetic valve prostheses and their specific advantages relative to valve repair or a Ross procedure. In current practice, young patients requiring aortic valve surgery frequently undergo valve replacement with a prosthetic valve. In STS adult cardiac database, among patients ≤30 years of age undergoing aortic valve surgery, 34% had placement of a mechanical valve, 51% had placement of a bioprosthetic valve, 9% had aortic valve repair, and 2% had a Ross procedure. In the STS congenital database, among patients 12 to 30 years of age undergoing aortic valve surgery, 21% had placement of a mechanical valve, 18% had placement of a bioprosthetic valve, 30% had aortic valve repair, and 24% had a Ross procedure. In the future, the balance among these options may be altered by design improvements in prosthetic valves, alternatives to warfarin, the development of new patch materials for valve repair, and techniques to avoid Ross autograft failure.

  5. Geometric Optimization for Non-Thrombogenicity of a Centrifugal Blood Pump through Computational Fluid Dynamic Analysis

    Science.gov (United States)

    Nishida, Masahiro; Yamane, Takashi

    A monopivot magnetic suspension blood pump has been developed in our laboratory. The flow patterns within the pump should be carefully examined in order to prevent thrombogenesis, especially around the pivot bearing. Therefore, the effects of the pump geometry on the local flow were analyzed using computational fluid dynamics together with the experimental flow visualization. The engineering goal was to reduce the area of stagnation around the pivot in order to prevent thrombus formation. As a result, the stagnation area and the flow rate through the washout holes were found to be highly affected by the size and geometry of the washout holes. Secondary flow was revealed to form a jet-like wash against the pivot, thus preventing thrombus formation. The flow rate through the washout holes was estimated to be up to one fifth of the pump flow rate, depending on the cross-sectional areas of the washout holes. Furthermore, an anti-thrombogenic effect was attained by removing a small gap between the male and female pivots.

  6. 3D velocity field characterization of prosthetic heart valve with two different valve testers by means of stereo-PIV.

    Science.gov (United States)

    D'Avenio, Giuseppe; Grigioni, Mauro; Daniele, Carla; Morbiducci, Umberto; Hamilton, Kathrin

    2015-01-01

    Prosthetic heart valves can be associated to mechanical loading of blood, potentially linked to complications (hemolysis and thrombogenicity) which can be clinically relevant. In order to test such devices in pulsatile mode, pulse duplicators (PDs) have been designed and built according to different concepts. This study was carried out to compare anemometric measurements made on the same prosthetic device, with two widely used PDs. The valve (a 27-mm bileaflet valve) was mounted in the aortic section of the PD. The Sheffield University PD and the RWTH Aachen PD were selected as physical models of the circulation. These two PDs differ mainly in the vertical vs horizontal realization, and in the ventricular section, which in the RWTH PD allows for storage of potential energy in the elastic walls of the ventricle. A glassblown aorta, realized according to the geometric data of the same anatomical district in healthy individuals, was positioned downstream of the valve, obtaining 1:1 geometric similarity conditions. A NaI-glycerol-water solution of suitable kinematic viscosity and, at the same time, the proper refractive index, was selected. The flow field downstream of the valve was measured by means of the stereo-PIV (Particle Image Velocimetry) technique, capable of providing the complete 3D velocity field as well as the entire Reynolds stress tensor. The measurements were carried out at the plane intersecting the valve axis. A three-jet profile was clearly found in the plane crossing the leaflets, with both PDs. The extent of the typical recirculation zone in the Valsalva sinus was much larger in the RWTH PD, on account of the different duration of the swirling motion in the ventricular chamber, caused by the elasticity of the ventricle and its geometry. The comparison of the hemodynamical behaviour of the same bileaflet valve tested in two PDs demonstrated the role of the mock loop in affecting the valve performance.

  7. 49 CFR 195.420 - Valve maintenance.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valve maintenance. 195.420 Section 195.420 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Operation and Maintenance § 195.420 Valve maintenance. (a) Each operator shall maintain each valve...

  8. Pregnancy in women with prosthetic heart valves

    NARCIS (Netherlands)

    Pieper, P. G.; Balci, A.; Van Dijk, A. P.

    2008-01-01

    Pregnancy in women with mechanical valve prostheses has a high maternal complication rate including valve thrombosis mid death. Coumarin derivatives are relatively safe for the mother with a lower incidence of valve thrombosis than unfractionated and low-molecular-weight heparin, but carry the risk

  9. Pregnancy in women with prosthetic heart valves.

    NARCIS (Netherlands)

    Pieper, P.G.; Balci, A.; Dijk, A.P.J. van

    2008-01-01

    Pregnancy in women with mechanical valve prostheses has a high maternal complication rate including valve thrombosis and death. Coumarin derivatives are relatively safe for the mother with a lower incidence of valve thrombosis than un-fractionated and low-molecular-weight heparin, but carry the risk

  10. Diagnostic accuracy of electrocardiographic P wave related parameters in the assessment of left atrial size in dogs with degenerative mitral valve disease.

    Science.gov (United States)

    Soto-Bustos, Ángel; Caro-Vadillo, Alicia; Martínez-DE-Merlo, Elena; Alonso-Alegre, Elisa González

    2017-10-07

    The purpose of this research was to compare the accuracy of newly described P wave-related parameters (P wave area, Macruz index and mean electrical axis) with classical P wave-related parameters (voltage and duration of P wave) for the assessment of left atrial (LA) size in dogs with degenerative mitral valve disease. One hundred forty-six dogs (37 healthy control dogs and 109 dogs with degenerative mitral valve disease) were prospectively studied. Two-dimensional echocardiography examinations and a 6-lead ECG were performed prospectively in all dogs. Echocardiography parameters, including determination of the ratios LA diameter/aortic root diameter and LA area/aortic root area, were compared to P wave-related parameters: P wave area, Macruz index, mean electrical axis voltage and duration of P wave. The results showed that P wave-related parameters (classical and newly described) had low sensitivity (range=52.3 to 77%; median=60%) and low to moderate specificity (range=47.2 to 82.5%; median 56.3%) for the prediction of left atrial enlargement. The areas under the curve of P wave-related parameters were moderate to low due to poor sensitivity. In conclusion, newly P wave-related parameters do not increase the diagnostic capacity of ECG as a predictor of left atrial enlargement in dogs with degenerative mitral valve disease.

  11. Piezoelectric valve

    Science.gov (United States)

    Petrenko, Serhiy Fedorovich

    2013-01-15

    A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

  12. Valve's Way

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Dobrajska, Magdalena

    2015-01-01

    to what extent it represents a new blueprint for organization design, despite it being consistent with an “egalitarian Zeitgeist” (Puranam, 2014). In fact, managerial authority may be of increasing importance rather than the opposite (Guadalupe, Li, & Wulf, 2015). Thus, Valve is, and will remain...

  13. Vacuum Valve

    CERN Multimedia

    1974-01-01

    This valve was used in the Intersecting Storage Rings (ISR) to protect against the shock waves that would be caused if air were to enter the vacuum tube. Some of the ISR chambers were very fragile, with very thin walls - a design required by physicists on the lookout for new particles.

  14. The principles and in vivo performance of the Edinburgh pivoted aerofoil-disc prosthetic heart valve.

    Science.gov (United States)

    Macleod, N; Turina, M; Wade, J D; Wheatley, D J

    1977-01-01

    Prototypes of the Edinburgh prosthetic heart valve, known from previous experiments in vitro to promote exceptionally smooth and undisturbed forward flow, have been shown here in canine experiments to possess hemodynamic characteristics not inferior to those of the Bjork-Shiley valve (a present standard of excellence). In addition, we report a low incidence of valve thrombus deposition among calves in which this prototype valve, fabricated from the conventional materials, Delrin and stainless steel, has been implanted in the tricuspid site for up to 100 days without use of anticoagulants. This suggests that the design of the valve is such as to render it of low thrombogenicity. The new valve is designed for fabrication throughout in vitreous or pyro-coated carbon, materials of very high inherent athrombogenicity. It appears from the results discussed here that the developed form of the prosthesis, composed wholly of these athrombogenic materials, is likely to have both acceptable hemodynamic characteristics and an exceptionally low tendency to form thrombus. The introduction of such valves promises to be very advantageous and the results given here appear to warrant their development as the next stage of this program.

  15. Butterfly valve. Spjeldventil

    Energy Technology Data Exchange (ETDEWEB)

    Cupedo, D.J.

    1984-02-06

    Butterfly valve comprising a body and a valve seat arranged therein, on which a valve member is supported. The valve member comprises an operating rod and the assembly of valve member and operating rod has a fixed pivot point at the bottom of the body. The operating rod can be moved by means of pins movable in grooves and slots in such a manner that when the valve is opened the valve member first pivots about the pivot point to lift the valve member from the seat and subsequently rotates about the pivot point to fully open the valve. 12 drawings.

  16. Aortic valve bypass

    DEFF Research Database (Denmark)

    Lund, Jens T; Jensen, Maiken Brit; Arendrup, Henrik

    2013-01-01

    In aortic valve bypass (AVB) a valve-containing conduit is connecting the apex of the left ventricle to the descending aorta. Candidates are patients with symptomatic aortic valve stenosis rejected for conventional aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI...

  17. Presence of B cells within aortic valves in patients with aortic stenosis: Relation to severity of the disease.

    Science.gov (United States)

    Natorska, Joanna; Marek, Grzegorz; Sadowski, Jerzy; Undas, Anetta

    2016-01-01

    Aortic stenosis (AS) shares several similarities with atherosclerosis. Recent reports showed that B cells are implicated in atherosclerosis progression through macrophage-B cells bidirectional interaction. We aimed to study the in loco presence of B cells within aortic valves and to determine its modulators. Thirty-seven patients with severe AS were studied. Immunohistochemistry was performed on valve leaflets using antibodies against CD20, B cell-activating factor of the tumor necrosis factor family receptor (BAFF-R) and CD68. Plasma inflammatory markers were also determined. The B cells were detected within aortic leaflets from 5 to 31/mm(2) (17.9±11.6/mm(2)). Double-staining showed that 27±13.5% of B cells express BAFF-R. There were positive correlations between the number of B cells and macrophages (r=0.45, p=0.018), and between macrophages and B cell-associated BAFF-R expression (r=0.66, p=0.002). The number of B cells was associated with the valve calcification (r=0.41, p=0.039), and with the maximum transvalvular gradient (r=0.63, p=0.02). The BAFF-R expression was positively correlated with maximum transvalvular gradient (r=0.39, p=0.031) and negatively with aortic valve area (r=-0.41, p=0.048). There were no correlations between the number of B cells and plasma markers. It might be hypothesized that, like in atherosclerosis, increasing number of B cells within aortic valves may accelerate inflammation and thus potentiate the progression of AS. Copyright © 2015 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  18. Effects of amount and type of dietary fats on postprandial lipemia and thrombogenic markers in individuals with metabolic syndrome.

    Science.gov (United States)

    Teng, Kim-Tiu; Chang, Chee-Yan; Kanthimathi, M S; Tan, Alexander Tong Boon; Nesaretnam, Kalanithi

    2015-09-01

    Postprandial lipemia has been reported to affect endothelial function by thrombogenic and inflammatory pathways. We set out to investigate the impact of a) specific amount (50 g vs 20 g fat), and b) type of fatty acids (saturated, monounsaturated or n-6 polyunsaturated fatty acids; SFA, MUFA, PUFA) on postprandial lipemia, thrombogenic and inflammatory factors in metabolic syndrome subjects. 30 subjects (15 men, 15 women) participated in a double-blind, randomized crossover design study with both the subjects and investigators blinded to treatments. Blood samples were collected at fasting and 30 min, hourly interval for a total of 6 h. As expected, lower triacylglycerol response was observed for low fat/high carbohydrate meal; whereas no difference was detected between the types of fatty acids. The incremental area under the curve (iAUC) for low fat/high carbohydrate meal was 70%, 81% and 61% lower than the SFA, MUFA and PUFA meals, respectively. The iAUC 0-6 h for triacylglycerol was 42% lower in women compared with the men (P = 0.024), with the similar trend observed for non-esterified fatty acids. There were significant meal × time interaction (P = 0.000) for plasma plasminogen activator inhibitor-1 and thromboxane B2 (P = 0.022) from baseline. No differences were observed between meals for plasma D-dimer, interleukin-6, interleukin-1β, tumor necrosis factor-α and high sensitivity C-reactive protein. These data indicate that in metabolic syndrome subjects, only the amount of dietary fatty acids affects postprandial lipemia but both amount and type of dietary fats alter thrombogenic factors. The study was registered at Clinicaltrials.gov (NCT01571947). Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  19. Aortic Valve Stenosis

    Science.gov (United States)

    ... rapid, fluttering heartbeat Not eating enough (mainly in children with aortic valve stenosis) Not gaining enough weight (mainly in children with aortic valve stenosis) The heart-weakening effects of aortic valve stenosis ...

  20. Surface Modification of Biodegradable Polymers towards Better Biocompatibility and Lower Thrombogenicity

    Science.gov (United States)

    Rudolph, Andreas; Teske, Michael; Illner, Sabine; Kiefel, Volker; Sternberg, Katrin; Grabow, Niels; Wree, Andreas; Hovakimyan, Marina

    2015-01-01

    Purpose Drug-eluting stents (DES) based on permanent polymeric coating matrices have been introduced to overcome the in stent restenosis associated with bare metal stents (BMS). A further step was the development of DES with biodegradable polymeric coatings to address the risk of thrombosis associated with first-generation DES. In this study we evaluate the biocompatibility of biodegradable polymer materials for their potential use as coating matrices for DES or as materials for fully bioabsorbable vascular stents. Materials and Methods Five different polymers, poly(L-lactide) PLLA, poly(D,L-lactide) PDLLA, poly(L-lactide-co-glycolide) P(LLA-co-GA), poly(D,L-lactide-co-glycolide) P(DLLA-co-GA) and poly(L-lactide-co-ε-caprolactone), P(LLA-co-CL) were examined in vitro without and with surface modification. The surface modification of polymers was performed by means of wet-chemical (NaOH and ethylenediamine (EDA)) and plasma-chemical (O2 and NH3) processes. The biocompatibility studies were performed on three different cell types: immortalized mouse fibroblasts (cell line L929), human coronary artery endothelial cells (HCAEC) and human umbilical vein endothelial cells (HUVEC). The biocompatibility was examined quantitatively using in vitro cytotoxicity assay. Cells were investigated immunocytochemically for expression of specific markers, and morphology was visualized using confocal laser scanning (CLSM) and scanning electron (SEM) microscopy. Additionally, polymer surfaces were examined for their thrombogenicity using an established hemocompatibility test. Results Both endothelial cell types exhibited poor viability and adhesion on all five unmodified polymer surfaces. The biocompatibility of the polymers could be influenced positively by surface modifications. In particular, a reproducible effect was observed for NH3-plasma treatment, which enhanced the cell viability, adhesion and morphology on all five polymeric surfaces. Conclusion Surface modification of

  1. Percutaneous approaches to mitral valve disease

    National Research Council Canada - National Science Library

    Fassa, A-A; Himbert, D; Brochet, E; Bouleti, C; Vahanian, A

    2015-01-01

    Percutaneous approaches to mitral valve disease consist in modifications of existing surgical techniques, aiming to replicate the favourable outcomes of surgery, with less procedure-related risk, due...

  2. What Is Heart Valve Disease?

    Science.gov (United States)

    ... Heart Valves Sometimes heart valves can’t be repaired and must be replaced. This surgery involves removing the faulty valve and replacing it with a man-made or biological valve. Biological valves are made ...

  3. Response of functional mitral regurgitation during dobutamine infusion in relation to changes in left ventricular dyssynchrony and mitral valve geometry.

    Science.gov (United States)

    Choi, Woong Gil; Kim, Soo Hyun; Kim, Soo Han; Park, Sang Don; Baek, Young Soo; Shin, Sung Hee; Woo, Sung Il; Kim, Dae Hyeok; Park, Keum Soo; Kwan, Jun

    2014-05-01

    Functional mitral regurgitation (FMR) and myocardial dyssynchrony commonly occur in patients with dilated cardiomyopathy (DCM). The aim of this study was to elucidate changes in FMR in relation to those in left ventricular (LV) dyssynchrony as well as geometric parameters of the mitral valve (MV) in DCM patients during dobutamine infusion. Twenty-nine DCM patients (M:F=15:14; age: 62±15 yrs) with FMR underwent echocardiography at baseline and during peak dose (30 or 40 ug/min) of dobutamine infusion. Using 2D echocardiography, LV end-diastolic volume, end-systolic volume (LVESV), ejection fraction (EF), and effective regurgitant orifice area (ERO) were estimated. Dyssynchrony indices (DIs), defined as the standard deviation of time interval-to-peak myocardial systolic contraction of eight LV segments, were measured. Using the multi-planar reconstructive mode from commercially available 3D image analysis software, MV tenting area (MVTa) was measured. All geometrical measurements were corrected (c) by the height of each patient. During dobutamine infusion, EF (28±8% vs. 39±11%, p=0.001) improved along with significant decrease in cLVESV (80.1±35.2 mm³/m vs. 60.4±31.1 mm³/m, p=0.001); cMVTa (1.28±0.48 cm²/m vs. 0.79±0.33 cm²/m, p=0.001) was significantly reduced; and DI (1.31±0.51 vs. 1.58±0.68, p=0.025) showed significant increase. Despite significant deterioration of LV dyssynchrony during dobutamine infusion, ERO (0.16±0.09 cm² vs. 0.09±0.08 cm², p=0.001) significantly improved. On multivariate analysis, ΔcMVTa and ΔEF were found to be the strongest independent determinants of ΔERO (R²=0.443, p=0.001). Rather than LV dyssynchrony, MV geometry determined by LV geometry and systolic pressure, which represents the MV closing force, may be the primary determinant of MR severity.

  4. Midterm outcomes of mechanical versus bioprosthetic valve replacement in middle-aged patients: An Indian scenario

    Directory of Open Access Journals (Sweden)

    Dheeraj Sharma

    2017-01-01

    Conclusions: Bioprosthetic heart valves seem to be more beneficial in the Indian scenario as compared to mechanical valves because of low incidence of mortality and valve-related events and better quality of life.

  5. Remote actuated valve implant

    Science.gov (United States)

    McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

    2014-02-25

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  6. Remote actuated valve implant

    Energy Technology Data Exchange (ETDEWEB)

    McKnight, Timothy E.; Johnson, Anthony; Moise, Kenneth J.; Ericson, Milton Nance; Baba, Justin S.; Wilgen, John B.; Evans, Boyd Mccutchen

    2016-05-10

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  7. Mitral valve regurgitation

    Science.gov (United States)

    ... around the valve. You are at risk for mitral valve regurgitation if you have: Coronary heart disease and high blood pressure Infection of the heart valves Mitral valve prolapse (MVP) Rare conditions, such as untreated syphilis or Marfan ... heart disease. This is a complication of untreated strep throat ...

  8. Tissue engineered aortic valve

    OpenAIRE

    Dohmen, P M

    2012-01-01

    Several prostheses are available to replace degenerative diseased aortic valves with unique advantages and disadvantages. Bioprotheses show excellent hemodynamic behavior and low risk of thromboembolic complications, but are limited by tissue deterioration. Mechanical heart valves have extended durability, but permanent anticoagulation is mandatory. Tissue engineering created a new generation heart valve, which overcome limitations of biological and mechanical heart valves due to remodelling,...

  9. Bioprosthetic heart valves of the future.

    Science.gov (United States)

    Manji, Rizwan A; Ekser, Burcin; Menkis, Alan H; Cooper, David K C

    2014-01-01

    Glutaraldehyde-fixed bioprosthetic heart valves (GBHVs), derived from pigs or cows, undergo structural valve deterioration (SVD) over time, with calcification and eventual failure. It is generally accepted that SVD is due to chemical processes between glutaraldehyde and free calcium ions in the blood. Valve companies have made significant progress in decreasing SVD from calcification through various valve chemical treatments. However, there are still groups of patients (e.g., children and young adults) that have accelerated SVD of GBHV. Unfortunately, these patients are not ideal patients for valve replacement with mechanical heart valve prostheses as they are at high long-term risk from complications of the mandatory anticoagulation that is required. Thus, there is no "ideal" heart valve replacement for children and young adults. GBHVs represent a form of xenotransplantation, and there is increasing evidence that SVD seen in these valves is at least in part associated with xenograft rejection. We review the evidence that suggests that xenograft rejection of GBHVs is occurring, and that calcification of the valve may be related to this rejection. Furthermore, we review recent research into the transplantation of live porcine organs in non-human primates that may be applicable to GBHVs and consider the potential use of genetically modified pigs as sources of bioprosthetic heart valves. © 2014 John Wiley & Sons A/S.

  10. Maximizing prosthetic valve size with the Top Hat supra-annular aortic valve

    DEFF Research Database (Denmark)

    Aagaard, Jan; Geha, Alexander S.

    2007-01-01

    -annular mechanical prostheses (CarboMedics, Inc., Arvada, CO, USA) at two institutions. Size frequency distribution was compared to published series, and to the manufacturer's US registry. The ventriculoaortic junction (VAJ) size was available in 234 patients, and compared to the size of the Top Hat valve implanted......BACKGROUND AND AIM OF THE STUDY: The CarboMedics Top Hat supra-annular aortic valve allows a one-size (and often two-size) increase over the standard intra-annular valve. This advantage should minimize the risk of patient-prosthesis mismatch, where the effective prosthetic valve orifice area...... is less than that of a normal valve. It is suggested that the ability to implant Top Hat valves having greater size, relative to standard intra-annular valves, may currently be under-utilized. Further, there has been some concern that Top Hat implantation can cause obstruction of the coronary ostia...

  11. Double-reed exhaust valve engine

    Science.gov (United States)

    Bennett, Charles L.

    2015-06-30

    An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a double reed outlet valve for controlling the flow of low-pressure working fluid out of the engine. The double reed provides a stronger force resisting closure of the outlet valve than the force tending to open the outlet valve. The double reed valve enables engine operation at relatively higher torque and lower efficiency at low speed, with lower torque, but higher efficiency at high speed.

  12. Hammock mitral valve: A rare case report

    Directory of Open Access Journals (Sweden)

    Veeresh F. Manvi

    2014-01-01

    Full Text Available Congenital mitral stenosis is a relatively rare disorder comprising 0.2% of all congenital heart defects. Hammock mitral valve producing severe mitral stenosis is a rare variant of congenital mitral stenosis. We report a 2-year-old boy who had hammock mitral valve producing severe mitral stenosis with severe pulmonary artery hypertension. He underwent successful surgical repair. Post-surgery, the mitral valve opening was adequate without residual stenosis or regurgitation. Pulmonary artery pressure had normalized. Follow-up data showed he had significant clinical and echocardiography improvement. This is the first reported case of successful surgical repair done for hammock mitral valve from our institute.

  13. Corrosion, wettability and thrombogenicity investigation of ion beam modified HAP/Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Shikha, Deep; Shahid, Md.; Jha, Ush [Department of Chemistry, BIT Mesra, Ranchi 835215 (India); Sinha, Sanjay Kumar, E-mail: sksinha@bitmesra.ac.in [Department of Physics, BIT Mesra, Ranchi 835215 (India); Reddy, V. Raghavendra [UGC-DAE Consortium for Scientific Research Indore (India); Ojha, Sunil; Kumar, P.; Kanjilal, Dinakar [IUAC, Aruna Asaf Ali road, New Delhi (India)

    2015-08-01

    Hydroxyapatite Ca{sub 10}(PO4){sub 6}(OH){sub 2}, is a biosensitive ceramic which promotes bone growth in human fluid. However due to its weak mechanical strength it is often coated on chemically inert material such as alumina. In the present work hydroxyapatite (HAP) of thickness 1 μm is deposited on alumina using sol–gel process and the stoichiometric ratio of Ca:P = 1.67 is maintained. Surface property of HAP is further improved by Ar{sup +} ion implantation. The samples were irradiated with 1.4 MeV Ar{sup +} ions with fluence ranging from 5 × 10{sup 14} to 1 × 10{sup 16} ions/cm{sup 2}. After irradiation, the surface is characterized using Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), electron dispersive X-ray spectroscopy (EDX), Glancing incidence X-ray diffraction (GXRD) and Rutherford backscattering Spectroscopy (RBS) techniques. Corrosion resistances and impedance analysis were carried out in Ringer solution. RBS and EDX were used to confirm the stoichiometric ratio of the film. Compound formation before and after ion implantation was studied using GXRD. Nanohardness, wettability and thrombogenicity of all the samples were studied. Correlation among surface morphology, improvement in corrosion resistance, hardness, wetability and thrombogenicity before and after ion implantation are discussed in this paper. - Highlights: • .People have worked on HAP coated on metallic alloy and even alumina but the characterization done here are all different. • Throbmobogenicity, corrosion resistance and wetability have all been carried out first time. • Improvement of Surface and interface using energetic inert ions like argon is carried out first time. • The best ion fluence for orthopaedic implants is proposed.

  14. THE ROLE OF ANTICOAGULATION THERAPY IN PATIENTS WITH PROSTHETIC HEART VALVES

    Directory of Open Access Journals (Sweden)

    N. A. Shostak

    2016-01-01

    Full Text Available Cardiac surgery is the only radical method of treatment of valvular defects (congenital or acquired: valve preservation procedures or prosthetics operations. 250 000 – 280 000 valve prostheses are implanted every year worldwide, while the number of prosthetic valves operation increases by an average of 5–7 % per year (biological prostheses – 8–11 %, mechanical prostheses – 3–5 %. Selection of biological or mechanical types of prosthesis, its location, the presence of associated risk factors for embolic events, such as atrial fibrillation, previous embolism, left ventricular dysfunction, hypercoagulable states determine patient management tactics. Particularly high risk of prosthetic thrombosis and thromboembolic complications can be seen in case of mechanical prosthesis implantation. Numerous prospective and retrospective clinical studies have proven high effectiveness of anticoagulants for reduction the risk of cardioembolic complications. The degree of anticoagulation (optimal international normalized ratio (INR is determined by risk factors for prosthetic thrombosis and thromboembolic complications in a patient, as well as thrombogenicity of the prosthesis by itself; INR may range from 2.5 to 4.0. International recommendations take into account the presence/absence of additional risk factors for thromboembolism, and based on warfarin administration with the achievement of target INR values combined with low-dose aspirin. Administration of novel direct oral anticoagulation remedies in patients with prosthetic heart valves has not been studied sufficiently up to date and is contraindicated. Thus, warfarin currently is a drug of choice for the prevention of thromboembolic complications in patients with prosthetic heart valves.

  15. Risks for Heart Valve Problems

    Science.gov (United States)

    ... Thromboembolism Aortic Aneurysm More Risks for Heart Valve Problems Updated:Jan 18,2017 Who is at risk ... content was last reviewed May 2016. Heart Valve Problems and Disease • Home • About Heart Valves • Heart Valve ...

  16. Living with Heart Valve Disease

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  17. What Causes Heart Valve Disease?

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  18. Sealing a Loosely Fitting Valve Assembly

    Science.gov (United States)

    Goff, L.; Tellier, G.

    1986-01-01

    Double-ring seal avoids expense of remachining or redesigning valve parts. Mating fittings on valve sealed by pair of rings - one O-ring and backup ring. Backup ring fills relatively large gap between parts. Prevents softer O-ring from being pushed into and through gap.

  19. Fluid flow regulator device, comprising a valve member and a valve seat defining a fluid flow surface area, as well as method of using the same

    NARCIS (Netherlands)

    Groen, Maarten; Brouwer, Dannis Michel; Brookhuis, Robert Anton; Wiegerink, Remco J.

    2014-01-01

    The invention relates to a fluid flow regulator device, comprising a valve member and a valve seat arranged to be movable with respect to each other such that a fluid flow surface area defined by the valve member and the valve seat can be changed. Furthermore, sensor means are provided for measuring

  20. 49 CFR 192.181 - Distribution line valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Distribution line valves. 192.181 Section 192.181 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... line valves. (a) Each high-pressure distribution system must have valves spaced so as to reduce the...

  1. Mitral valve prolapse

    Science.gov (United States)

    ... mitral valve prolapse is called "mitral valve prolapse syndrome," and includes: Chest pain (not caused by coronary artery disease or a heart attack) Dizziness Fatigue Panic attacks Sensation of feeling the heart beat ( palpitations ) ...

  2. Mitral Valve Stenosis

    Science.gov (United States)

    ... valve stenosis include: Rheumatic fever. A complication of strep throat, rheumatic fever can damage the mitral valve. Rheumatic ... children see your doctor for sore throats. Untreated strep throat infections can develop into rheumatic fever. Fortunately, strep ...

  3. Matched Comparison of Self-Expanding Transcatheter Heart Valves for the Treatment of Failed Aortic Surgical Bioprosthesis: Insights From the Valve-in-Valve International Data Registry (VIVID).

    Science.gov (United States)

    Alnasser, Sami; Cheema, Asim N; Simonato, Matheus; Barbanti, Marco; Edwards, Jeremy; Kornowski, Ran; Horlick, Eric; Wijeysundera, Harindra C; Testa, Luca; Bedogni, Francesco; Amrane, Hafid; Walther, Thomas; Pelletier, Marc; Latib, Azeem; Laborde, Jean-Claude; Hildick-Smith, David; Kim, Won-Keun; Tchetche, Didier; Agrifoglio, Marco; Sinning, Jan-Malte; van Boven, Ad J; Kefer, Joëlle; Frerker, Christian; van Mieghem, Nicolas M; Linke, Axel; Worthley, Stephen; Asgar, Anita; Sgroi, Carmelo; Aziz, Mina; Danenberg, Haim D; Labinaz, Marino; Manoharan, Ganesh; Cheung, Anson; Webb, John G; Dvir, Danny

    2017-04-01

    Transcatheter valve-in-valve implantation is an established therapy for high-risk patients with failed surgical aortic bioprosthesis. There are limited data comparing outcomes of valve-in-valve implantation using different transcatheter heart valves (THV). Patients included in the Valve-in-Valve International Data registry (VIVID) and treated with self-expanding THV devices were analyzed using centralized core laboratory blinded to clinical events. St. Jude Medical Portico versus Medtronic CoreValve were compared in a 1:2 fashion after propensity score matching. A total of 162 patients, Portico- (n=54) and CoreValve- (n=108) based valve-in-valve procedures comprised the study population with no significant difference in baseline characteristics (age, 79±8.2 years; 60% women; mean STS [Society of Thoracic Surgery] score 8.1±5.5%). Postimplantation, CoreValve was associated with a larger effective orifice area (1.67 versus 1.31 cm2; P=0.001), lower mean gradient (14±7.5 versus 17±7.5 mm Hg; P=0.02), and lower core laboratory-adjudicated moderate-to-severe aortic insufficiency (4.2% versus 13.7%; P=0.04), compared with Portico. Procedural complications including THV malpositioning, second THV requirement, or coronary obstruction were not significantly different between the 2 groups. Survival and stroke rates at 30 days were similar, but overall mortality at 1 year was higher among patients treated with Portico compared with CoreValve (22.6% versus 9.1%; P=0.03). In this first matched comparison of THVs for valve-in-valve implantations, Portico and CoreValve demonstrated differences in postprocedural hemodynamics and long-term clinical outcomes. Although this could be related to THV design characteristics, the impact of other procedural factors cannot be excluded and require further evaluation. © 2017 American Heart Association, Inc.

  4. 3D Printed Trileaflet Valve Conduits Using Biological Hydrogels and Human Valve Interstitial Cells

    Science.gov (United States)

    Duan, Bin; Kapetanovic, Edi; Hockaday, Laura A.; Butcher, Jonathan T.

    2014-01-01

    Tissue engineering has great potential to provide a functional de novo living valve replacement capable of integration with host tissue and growth. Among various valve conduit fabrication techniques, 3D bioprinting enables deposition of cells and hydrogels into 3D constructs with anatomical geometry and heterogeneous mechanical properties. Successful translation of this approach is however constrained by the dearth of printable and biocompatible hydrogel materials. Furthermore, it is not known how human valve cells respond to these printed environments. In this study, we develop 3D printable formulations of hybrid hydrogels based on methacrylated hyaluronic acid (Me-HA) and methacrylated gelatin (Me-Gel), and utilize them to bioprint heart valve conduits containing encapsulated human aortic valvular interstitial cells (HAVIC). Increasing Me-Gel concentration resulted in lower stiffness and higher viscosity, facilitated cell spreading, and better maintained HAVIC fibroblastic phenotype. Bioprinting accuracy was dependent upon the relative concentrations of Me-Gel and Me-HA, but when optimized enabled the fabrication of a trileaflet valve shape accurate to the original design. HAVIC encapsulated within bioprinted heart valves maintained high viability, and remodeled the initial matrix by depositing collagen and glyosaminoglycans. These findings represent the first rational design of bioprinted trileaflet valve hydrogels that regulate encapsulated human VIC behavior. The use of anatomically accurate living valve scaffolds through bioprinting may accelerate our understanding of physiological valve cell interactions and our progress towards de novo living valve replacements. PMID:24334142

  5. Isolated Pulmonary Valve Endocarditis

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Hatamizadeh

    2009-06-01

    Full Text Available Infective endocarditis is one of the most severe complications of parenteral drug abuse. The outstanding clinical feature of infective endocarditis in intravenous drug abusers is the high incidence of right-sided valve infection, and the tricuspid valve is involved in 60% to 70% of the cases. We herein report a case of isolated pulmonic valve infective endocarditis with a native pulmonary valve.

  6. A case of SAPIEN XT valve fallen into left ventricle during valve-in-valve transcatheter aortic valve implantation.

    Science.gov (United States)

    Koizumi, Shigeki; Ehara, Natsuhiko; Nishiya, Kenta; Koyama, Tadaaki

    2017-06-24

    Late transcatheter heart valve embolization is a rare but life-threatening complication of transcatheter aortic valve implantation. Surgical intervention is performed for most cases, but some cases were treated by valve-in-valve transcatheter aortic valve implantation. We describe a patient in whom a 29-mm Edwards SAPIEN XT valve migrated into the left ventricular outflow tract 41 days after the initial implantation. We tried to perform valve-in-valve transcatheter aortic valve implantation using a transfemoral approach. As soon as the second transcatheter heart valve touched the first implanted valve, it fell into the left ventricle. Immediate surgical intervention was required. The first valve was removed, and surgical aortic valve replacement was successfully performed. In conclusion, we should choose surgical aortic valve replacement for late transcatheter heart valve embolization. Even if we need to treat by catheter intervention, transapical approach may be better.

  7. Heart Valve Diseases

    Science.gov (United States)

    Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

  8. Mechanical heart valve cavitation in patients with bileaflet valves.

    Science.gov (United States)

    Johansen, Peter; Andersen, Tina S; Hasenkam, J Michael; Nygaard, Hans; Paulsen, Peter K

    2014-01-01

    Today, the quality of mechanical heart valves is quite high, and implantation has become a routine clinical procedure with a low operative mortality (mechanism found to be a possible contributor to these adverse effects is cavitation. In vitro, cavitation has been directly demonstrated by visualization and indirectly in vivo by registering of high frequency pressure fluctuations (HFPF). Tilting disc valves are thought of having higher cavitation potential than bileaflet valves due to higher closing velocities. However, the thromboembolic potential seems to be the same. Further studies are therefore needed to investigate the cavitation potential of bileaflet valves in vivo. The post processing of HFPF have shown difficulties when applied on bileaflet vavles due to asynchronous closure of the two leaflets. The aim of this study was therefore to isolate the pressure signature from each leaflet closure and perform cavitation analyses on each component. Six patients were included in the study (St. Jude Medical (n=3) and CarboMedics (n=3); all aortic bileaflet mechanical heart valves). HFPFs were recorded intraoperatively through a hydrophone at the aortic root. The pressure signature relating to the first and second leaflet closure was isolated and cavitation parameters were calculated (RMS after 50 kHz highpass filtering and signal energy). Data were averaged over 30 heart cycles. For all patients both the RMS value and signal energy of the second leaflet closure were higher than for the first leaflet closure. This indicates that the second leaflet closure is most prone to cause cavitation. Therefore, quantifying cavitation based on the HFPF related to the second leaflet closure may suggest that the cavitation potential for bileaflet valves in vivo may be higher than previous studies have suggested.

  9. Predictive modelization of actuators tires in related valves with safety Cofrentes NPP; Modelizacion predictiva de actuadores neumaticos en valvulas relacionadas con la seguridad de C.N.Cofrentes

    Energy Technology Data Exchange (ETDEWEB)

    Calduch Cervera, F.; Verdu Rios, M. F.; Villena Rivera, M.; Munoz Guijosa, J. M.

    2011-07-01

    The main function of these valves is isolation, and in some cases this function is especially critical because they must isolate Elementary and Secondary Containment. Particularly valves must be able to ensure a perfect sealing of the lines which are installed under any conditions, whether in normal operation or in a design basis accident scenario.

  10. Predictive Modelling of Pneumatic Actuators in valves Related with security CN Cofrentes; Modelizacion Predictiva de Actuadores Neumaticos en Valvulas Relacionadas con la Seguridad de C. N. Cofrentes

    Energy Technology Data Exchange (ETDEWEB)

    Calduch Cervera, F.; Verdu Rios, M. F.; Villena Rivera, M.; Munoz Guijosa, J. M.

    2012-07-01

    Once completed the static modeling; pneumatic actuators under analysis, consisting in the development of balance equations Kinematic compatibility forces and each of the internal components of the actuator, regardless of the valve to which it is attached and the effect dynamic conditions of the line has continued to develop the dynamic model of the valve - actuator.

  11. Novel Active Combustion Control Valve

    Science.gov (United States)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  12. Fatty acid and cholesterol profiles and hypocholesterolemic, atherogenic, and thrombogenic indices of table eggs in the retail market.

    Science.gov (United States)

    Attia, Youssef A; Al-Harthi, Mohammed A; Korish, Mohamed A; Shiboob, Mohamed M

    2015-10-27

    Eggs are an important source of food due to its favorable effects on human health derived from the protein, fats, minerals, vitamins and bioactive components. We studied the effects of source of eggs in the retail market on fatty acids, lipid profiles and antioxidant status in eggs. Eggs from four sources named A, B, C, and D in the retail market were collected to determine fatty acid, total lipid, and cholesterol profiles; hypocholesterolemic, atherogenic and thrombotic indices; antioxidant status (e.g., of malondialdehyde); and total antioxidant capacity in the whole edible parts of eggs (albumen + yolk) and egg yolk. Samples were collected four times and pooled over times to represent 5 and 10 samples per source for determinations of fatty acids and determinations of lipid profiles and antioxidant status, respectively. Fatty acid, total lipid, and cholesterol profiles; hypocholesterolemic, atherogenic and thrombotic indices; presence of malondialdehyde; and total antioxidant capacity in the whole edible parts of eggs and egg yolk showed significant differences (P ≥ 0.05) among different sources of eggs in retail market. Source D showed higher levels of saturated fatty acids (SFA) and linoleic and monounsaturated fatty acid (MUFA)/polyunsaturated fatty acid (PUFA) ratio but lower levels of MUFA and linolenic, arachidonic, eicosapentaeonic (EPA), decohexaenoic (DHA), and total ω9 fatty acids and lower unsaturated fatty acids (UFA)/SFA ratio. Similar trend was shown in fatty acids profiles of the whole edible parts of eggs. On the other hand, total cholesterol, low density lipoprotein (LDL), LDL/high density lipoprotein (HDL) ratio, and atherogenic and thrombogenic indices and total antioxidant capacity of source D were significantly higher than those of other source, but levels of hypocholesterolemic index, and malondialdehyde levels were lower for source D. Eggs in the retail market in Jeddah city, Saudi Arabia, from May to August 2015 showed a

  13. Main Oxidizer Valve Design

    Science.gov (United States)

    Addona, Brad; Eddleman, David

    2015-01-01

    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  14. Mitral valve disease--morphology and mechanisms.

    Science.gov (United States)

    Levine, Robert A; Hagége, Albert A; Judge, Daniel P; Padala, Muralidhar; Dal-Bianco, Jacob P; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H; Clusel, Catherine; Delling, Francesca N; Dietz, Harry C; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D; Jensen, Morten O; Jeunemaitre, Xavier P; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R; Mérot, Jean; Messas, Emmanuel; Milan, David P; Neri, Tui; Norris, Russell A; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A; Song, Jae-Kwan; Yacoub, Magdi H

    2015-12-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

  15. Mitral valve disease—morphology and mechanisms

    Science.gov (United States)

    Levine, Robert A.; Hagége, Albert A.; Judge, Daniel P.; Padala, Muralidhar; Dal-Bianco, Jacob P.; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T.; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H.; Clusel, Catherine; Delling, Francesca N.; Dietz, Harry C.; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D.; Jensen, Morten O.; Jeunemaitre, Xavier P.; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R.; Mérot, Jean; Messas, Emmanuel; Milan, David P.; Neri, Tui; Norris, Russell A.; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A.; Song, Jae-Kwan; Yacoub, Magdi H.

    2016-01-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but—even in adult life—remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular–ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease. PMID:26483167

  16. Concomitant mitral valve surgery with aortic valve replacement: a 21-year experience with a single mechanical prosthesis

    Directory of Open Access Journals (Sweden)

    Sidhu Pushpinder

    2007-05-01

    Full Text Available Abstract Background Long-term survival for combined aortic and mitral valve replacement appears to be determined by the mitral valve prosthesis from our previous studies. This 21-year retrospective study assess long-term outcome and durability of aortic valve replacement (AVR with either concomitant mitral valve replacement (MVR or mitral valve repair (MVrep. We consider only a single mechanical prosthesis. Methods Three hundred and sixteen patients underwent double valve replacement (DVR (n = 273 or AVR+MVrep (n = 43, in the period 1977 to 1997. Follow up of 100% was achieved via telephone questionnaire and review of patients' medical records. Actuarial analysis of long-term survival was determined by Kaplan-Meier method. The Cox regression model was used to evaluate potential predictors of mortality. Results There were seventeen cases (5.4% of early mortality and ninety-six cases of late mortality. Fifteen-year survival was similar in both groups at 44% and 57% for DVR and AVR+MVrep respectively. There were no significant differences in valve related deaths, anticoagulation related complications, or prosthetic valve endocarditis between the groups. There were 6 cases of periprosthetic leak in the DVR group. Sex, pre-operative mitral and aortic valve pathology or previous cardiac surgery did not significantly affect outcome. Conclusion The mitral valve appears to be the determinant of survival following double valve surgery and survival is not significantly influenced by mitral valve repair.

  17. Surgery for rheumatic tricuspid valve disease: a 30-year experience.

    Science.gov (United States)

    Bernal, José M; Pontón, Alejandro; Diaz, Begoña; Llorca, Javier; García, Iván; Sarralde, Aurelio; Diago, Carmen; Revuelta, José M

    2008-08-01

    This study was undertaken to assess factors influencing short- and long-term outcomes of surgery for rheumatic disease of the tricuspid valve. Between 1974 and 2005, a total of 328 consecutive patients (mean age 51.3 +/- 13.6 years) underwent tricuspid valve surgery for rheumatic disease. There were 12 cases of isolated tricuspid lesion, 199 of triple-valve disease, 114 of tricuspid and mitral valve disease, and 3 of aortic and tricuspid valve disease. Most patients (72%) had predominantly tricuspid regurgitation. Tricuspid valve prosthetic replacement was performed in 31 cases and valve repair in 297. In-hospital mortality was 7.6%. Late mortality was 52.1%, whereas the expected mortality of the Spanish population of the same age was 24.2%. Predictors of in-hospital mortality were male sex, isolated tricuspid lesion, moderate aortic insufficiency, postclamping time, and tricuspid valve replacement. Mean follow-up was 8.7 years (range 1-31 years). Follow-up was 98.9% complete. Predictors of late mortality were age, New York Heart Association functional class IV, postclamping time, and mitral valve replacement. In total, 114 patients required valve reoperation, but only 4 (3.5%) for isolated tricuspid valve dysfunction. At 30 years, actuarial survival was 12.1% +/- 4.4%, actuarial freedom from reoperation was 27.5% +/- 5.8%, and actuarial freedom from valve-related complications was 2.0% +/- 1.3%. Organic tricuspid valve disease associated with rheumatic mitral or aortic lesions increases hospital and late mortality, but valve repair compared favorably with valve replacement. Long-term results may be considered acceptable for otherwise incurable valve disease.

  18. High Reliability Cryogenic Piezoelectric Valve Actuator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Piezoelectric actuators constructed with the "smart material" PZT offer many potential advantages for use in NASA cryo-valve missions relative to conventional...

  19. Cryogenic Cam Butterfly Valve

    Science.gov (United States)

    McCormack, Kenneth J. (Inventor)

    2016-01-01

    A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

  20. Intelligent Flow Control Valve

    Science.gov (United States)

    Kelley, Anthony R (Inventor)

    2015-01-01

    The present invention is an intelligent flow control valve which may be inserted into the flow coming out of a pipe and activated to provide a method to stop, measure, and meter flow coming from the open or possibly broken pipe. The intelligent flow control valve may be used to stop the flow while repairs are made. Once repairs have been made, the valve may be removed or used as a control valve to meter the amount of flow from inside the pipe. With the addition of instrumentation, the valve may also be used as a variable area flow meter and flow controller programmed based upon flowing conditions. With robotic additions, the valve may be configured to crawl into a desired pipe location, anchor itself, and activate flow control or metering remotely.

  1. Magnetic Check Valve

    Science.gov (United States)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-01-01

    Poppet in proposed check valve restored to closed condition by magnetic attraction instead of spring force. Oscillations suppressed, with consequent reduction of wear. Stationary magnetic disk mounted just upstream of poppet, also containing magnet. Valve body nonmagnetic. Forward pressure or flow would push poppet away from stationary magnetic disk so fluid flows easily around poppet. Stop in valve body prevents poppet from being swept away. When flow stopped or started to reverse, magnetic attraction draws poppet back to disk. Poppet then engages floating O-ring, thereby closing valve and preventing reverse flow. Floating O-ring facilitates sealing at low loads.

  2. Numerical Analysis for Structural Safety Evaluation of Butterfly Valves

    Science.gov (United States)

    Shin, Myung-Seob; Yoon, Joon-Yong; Park, Han-Yung

    2010-06-01

    Butterfly valves are widely used in current industry to control the fluid flow. They are used for both on-off and throttling applications involving large flows at relatively low operating pressure especially in large size pipelines. For the industrial application of butterfly valves, it must be ensured that the valve could be used safety under the fatigue life and the deformations produced by the pressure of the fluid. In this study, we carried out the structure analysis of the body and the valve disc of the butterfly valve and the numerical simulation was performed by using ANSYS v11.0. The reliability of valve is evaluated under the investigation of the deformation, the leak test and the durability of the valve.

  3. Fatty acid and cholesterol profiles, hypocholesterolemic, atherogenic, and thrombogenic indices of broiler meat in the retail market.

    Science.gov (United States)

    Attia, Youssef A; Al-Harthi, Mohammed A; Korish, Mohamed A; Shiboob, Mohamed M

    2017-02-16

    Broiler meat is an essential source of food due to its favourable effects on human health derived from its protein, fats, minerals, vitamins and its bioactive components. A total of 90 carcasses were collected from the retail market in Jeddah city, Saudi Arabia during April, May and June 2014 to determine the effects of meat type (frozen vs. fresh) and sources within fresh types (A, B, C) vs. frozen types (D, E and F) on their fatty acid profiles, cholesterol, their hypocholesterolemic, atherogenic and thrombogenic indices, and on their antioxidants' status. The sources of meat had a significant effect on the hypocholesterolemic and atherogenic indices, with the D source of fresh meat having the best indices. Total saturated fatty acids (SFA), unsaturated fatty acids (UFA), the UFA/SAF ratio, and the monounsaturated (MUFA), Omega-6 and Omega-7 fatty acids were significantly affected by the source of meat. The results revealed that the D source of fresh meat showed favourable fatty acid profiles with significant health benefits for human. Correlation analyses showed a significant negative relationship between the SFA and hypocholesterolemic indices, and significant positive relationships with the atherogenic index, the thrombotgenic index and the total antioxidant capacity. In addition, the relationship between UFA and the hypocholesterolemic index was strongly significantly positive, but was highly negative between the atherogenic and thrombotic indices. The correlations between omega-6 and total cholesterol and the atherogenic index was moderately negative, but was moderately positive with the hypocholesterolemic index. Fatty acids profiles and the hypocholesterolemic and atherogenic indices of broiler meat in the retail market in Jeddah city, Saudi Arabia during April-May-June showed significant differences, with the potential for favourable fatty acids to be boosted. Such variability indicates the needs for a feeding strategy to enhance the favourable fatty

  4. Combined mitral and tricuspid valve repair in rheumatic valve disease: fewer reoperations with prosthetic ring annuloplasty.

    Science.gov (United States)

    Bernal, José M; Pontón, Alejandro; Diaz, Begoña; Llorca, Javier; García, Iván; Sarralde, J Aurelio; Gutiérrez-Morlote, Jesús; Pérez-Negueruela, Carolina; Revuelta, José M

    2010-05-04

    We examined predictors of early and very long-term outcome after combined mitral and tricuspid valve repair for rheumatic disease. Between 1974 and 2002, 153 consecutive patients (mean age, 46.0+/-13.2 years) underwent combined mitral and tricuspid valve repair for rheumatic disease. Mitral disease was predominantly stenosis (82.3%); 100% of patients had organic tricuspid valve disease, predominantly with regurgitation (53.6%) or some degree of tricuspid stenosis (46.4%). Mitral repair included commissurotomy in 132 patients (86.3%) associated with a flexible annuloplasty in 108. Tricuspid valve repair included flexible annuloplasty in 68 patients (44.4%) and suture annuloplasty in 20 patients (13.1%) combined with tricuspid commissurotomy in 62 patients (42.5%). Thirty-day mortality was 5.9%. Late mortality was 60.1%. The median follow-up was 15.8 years (interquartile range, 6 to 19 years). Follow-up was 97.9% complete. Age>65 years was the only predictor of late mortality. Kaplan-Meier survival probability was 74.4% at 10 years and 57.0% at 15 years. Sixty-three patients required valve reoperation (mitral valve, 59; tricuspid valve, 38). Predictors of valve reoperations were either mitral or tricuspid commissurotomy without associated prosthetic ring annuloplasty. At 20 years, Kaplan-Meier freedom from reoperation was 48.5+/-5.1%. Combined mitral and tricuspid valve repair in rheumatic disease showed satisfactory early results. Long-term results were poor because of high mortality and a high number of valve-related reoperations. The use of prosthetic ring annuloplasty was significantly associated with a reduced incidence of both mitral and tricuspid valve reoperations.

  5. Replaceable valve seat

    Science.gov (United States)

    Jordan, Raymond W.

    1992-01-01

    A valve with an O-ring, a disk seal, and a replaceable valve seat is presented. A groove in the bottom on the valve seat flange forms an inner and outer drip ledge with the inner and outer periphery of the flange. If leakage occurs at the valve seat O-ring, fluid droplets will form on the out drip ledge. If leakage occurs at the disk seal, fluid droplets will form on the inner drip ledge. A visual inspection of these drip ledges through an access port, or by a borescope placed in an inspection port, can discriminate between a leak which originates in the O-ring and a leak which originates in the disk seal. When conventional replaceable valve seats leak, fluid droplets form at the bottom on the valve seat. In the present invention, such a valve seat is modified by machining a groove on the bottom surface of the valve seat flange. This groove and the inner and outer surfaces of the flange intersect and form drip ledges. If leakage occurs at the valve seat seal, shown as an O-ring in the preferred embodiment, fluid droplets will form on the outer drip ledge. If leakage occurs at the valve disk seal, fluid droplets will form on the inner drip ledge. The drip ledges can be inspected either through an access port or by passing a borescope through a small inspection port in the valve case. Visual inspection of the bottom on the drip ledge will positively identify the required repair action.

  6. Valve reconstruction for congenital mitral valve disease.

    Science.gov (United States)

    Quinonez, Luis G; Del Nido, Pedro J

    2015-01-01

    The surgical treatment of mitral valve disease in children is a challenging problem. Mitral stenosis and regurgitation may occur in isolation or together. Mitral valve repair is almost always preferable to replacement. Mitral valve replacement is not an ideal alternative to repair due to limitations of size, growth, structural valve degeneration, anticoagulation and poor survival. Surgical repair of congenital mitral stenosis must address the multiple levels of obstruction, including resection of the supramitral ring, thinning of leaflets and mobilization of the subvalvular apparatus. Sometimes leaflet augmentation is required. Repair of mitral regurgitation in children may involve simple cleft closures, edge-to-edge repairs, triangular resections and annuloplasties. Techniques used in adults, such as annuloplasty bands or artificial chords, may not be appropriate for children. Overall, an imperfect mitral valve repair may be more acceptable than the negative consequences of a replacement in a child. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  7. Simplified surgical-hybrid Melody valve implantation for paediatric mitral valve disease.

    Science.gov (United States)

    Hofmann, Michael; Dave, Hitendu; Hübler, Michael; Kretschmar, Oliver

    2015-05-01

    Children suffering from left atrioventricular valve (LAVV) disease not amenable to repair represent a significant challenge. The results of surgical reconstruction are not optimal. Valve replacement as an alternative is associated with poor results. The surgical-hybrid approach with implantation of a stented biological valve (bovine jugular vein graft, Melody valve) seems to represent a new therapeutic option. Here we demonstrate our case, the consideration and the approach to extreme clinical findings in a small child. We describe a simplified surgical-hybrid Melody valve implantation in a LAVV position. The technique of implantation is relatively simple and the immediate postoperative result very good. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  8. Problem: Mitral Valve Regurgitation

    Science.gov (United States)

    ... State SELECT YOUR LANGUAGE Español (Spanish) 简体中文 (Traditional Chinese) 繁体中文 (Simplified Chinese) Tiếng Việt (Vietnamese) Healthy Living for Heart.org ... each time the left ventricle contracts. Watch an animation of mitral valve regurgitation A leaking mitral valve ...

  9. Problem: Heart Valve Regurgitation

    Science.gov (United States)

    ... State SELECT YOUR LANGUAGE Español (Spanish) 简体中文 (Traditional Chinese) 繁体中文 (Simplified Chinese) Tiếng Việt (Vietnamese) Healthy Living for Heart.org ... should be completely closed For example: Watch an animation of mitral valve regurgitation A leaking mitral valve ...

  10. Mitral Valve Prolapse

    Science.gov (United States)

    ... State SELECT YOUR LANGUAGE Español (Spanish) 简体中文 (Traditional Chinese) 繁体中文 (Simplified Chinese) Tiếng Việt (Vietnamese) Healthy Living for Heart.org ... valve syndrome . What happens during MVP? Watch an animation of mitral valve prolapse When the heart pumps ( ...

  11. Mitral Valve Disease

    Science.gov (United States)

    ... clots, but they also are less durable than mechanical valves and may need to be replaced in the future. Like mitral valve repair, replacement can be done minimally invasively or with traditional open heart surgery. Your medical team will discuss the advantages ...

  12. Measuring what matters to the patient: health related quality of life after aortic valve and thoracic aortic surgery

    NARCIS (Netherlands)

    de Heer, Frederiek; Gökalp, Arjen L.; Kluin, Jolanda; Takkenberg, Johanna J. M.

    2017-01-01

    With improved outcomes following cardiac surgery, health related quality of life (HRQoL) gains increasing importance for the better judgement of choosing the preferred treatment strategy in the individual patient. The physician perception of patient preferences can differ considerably from actual

  13. Measuring what matters to the patient: health related quality of life after aortic valve and thoracic aortic surgery

    NARCIS (Netherlands)

    F. de Heer (Frederiek); Gökalp, A.L. (Arjen L.); J. Kluin (Jolanda); J.J.M. Takkenberg (Hanneke)

    2017-01-01

    textabstractWith improved outcomes following cardiac surgery, health related quality of life (HRQoL) gains increasing importance for the better judgement of choosing the preferred treatment strategy in the individual patient. The physician perception of patient preferences can differ considerably

  14. Transcatheter aortic valve implantation for bicuspid aortic valve stenosis.

    Science.gov (United States)

    Hamdan, Ashraf; Kornowski, Ran

    2015-08-01

    In Preprocedural CT, patients with BAV have larger aortic annulus perimeters, and more calcified valves compared with TAV. In patients with BAV, self-expandable valves were under-expand and balloon-expandable valves have a trend toward increased rates of postimplantation AR grade. Self-expandable valves have higher postprocedural gradient in BAV compared with TAV. © 2015 Wiley Periodicals, Inc.

  15. Aortic Dilatation Associated With Bicuspid Aortic Valve: Relation to Sex, Hemodynamics, and Valve Morphology (the National Heart Lung and Blood Institute-Sponsored National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions).

    Science.gov (United States)

    Roman, Mary J; Pugh, Norma L; Devereux, Richard B; Eagle, Kim A; Holmes, Kathryn; LeMaire, Scott A; Milewski, Rita K; Morris, Shaine A; Prakash, Siddharth K; Pyeritz, Reed E; Ravekes, William J; Shohet, Ralph V; Song, Howard K; Asch, Federico M

    2017-10-01

    This study analyzed the impact of sex, hemodynamic profile, and valve fusion pattern on aortopathy associated with bicuspid aortic valve (BAV). The National Heart Lung and Blood Institute-sponsored National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC) provided comprehensive information on a large population of well-characterized patients with BAV. Of 969 enrolled patients with BAV, 551 (57%, 77% male) had already undergone valvular and/or aortic surgery. Echocardiographic imaging data were available on 339 unoperated or preoperative participants who formed the basis of this study. BAV function was normal in 45 (14%), with a predominant aortic regurgitation (AR) in 127 (41%) and a predominant aortic stenosis (AS) in 76 (22%). Moderate-severe AR was associated with larger sinus of Valsalva (SOV) diameters compared with normal function and AS (all p Right-left commissural fusion was associated with a larger SOV diameter (3.7 ± 0.7 vs 3.3 ± 0.6 cm, p right-noncoronary fusion pattern. Predominant AR was more common in men (45% vs 27%, p = 0.004), whereas AS was more common in women (29% vs 18%, p = 0.04). In conclusion, in the GenTAC Registry, AR was associated with diffuse (annular, SOV, and AscAo) enlargement, whereas moderate-severe AS was only associated with AscAo enlargement. Male sex and right-left cusp pattern of cusp fusion were associated with larger SOV diameters and a greater likelihood of AR, whereas women had a higher prevalence of AS. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Face-Sealing Butterfly Valve

    Science.gov (United States)

    Tervo, John N.

    1992-01-01

    Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

  17. [MINIMALLY INVASIVE AORTIC VALVE REPLACEMENT].

    Science.gov (United States)

    Tabata, Minoru

    2016-03-01

    Minimally invasive aortic valve replacement (MIAVR) is defined as aortic valve replacement avoiding full sternotomy. Common approaches include a partial sternotomy right thoracotomy, and a parasternal approach. MIAVR has been shown to have advantages over conventional AVR such as shorter length of stay and smaller amount of blood transfusion and better cosmesis. However, it is also known to have disadvantages such as longer cardiopulmonary bypass and aortic cross-clamp times and potential complications related to peripheral cannulation. Appropriate patient selection is very important. Since the procedure is more complex than conventional AVR, more intensive teamwork in the operating room is essential. Additionally, a team approach during postoperative management is critical to maximize the benefits of MIAVR.

  18. GIANT PROSTHETIC VALVE THROMBUS

    Directory of Open Access Journals (Sweden)

    Prashanth Kumar

    2015-04-01

    Full Text Available Mechanical prosthetic valves are predisposed to bleeding, thrombosis & thromboembolic complications. Overall incidence of thromboembolic complications is 1% per year who are on oral anticoagulants, whereas bleeding complications incidence is 0.5% to 6.6% per year. 1, 2 Minimization of Scylla of thromboembolic & Charybdis of bleeding complication needs a balancing act of optimal antithrombotic therapy. We are reporting a case of middle aged male patient with prosthetic mitral valve presenting in heart failure. Patient had discontinued anticoagulants, as he had subdural hematoma in the past. He presented to our institute with a giant prosthetic valve thrombus.

  19. Ex vivo assessment of valve thickness/calcification of patients with calcific aortic stenosis in relation to in vivo clinical outcomes.

    Science.gov (United States)

    Cheng, Ching-Li; Chang, Hsiao-Huang; Huang, Pei-Jung; Wang, Wei-Chen; Lin, Shan-Yang

    2017-10-01

    Calcific aortic stenosis (AS) plays a critical role in the risk of cardiovascular disease. This preliminary study examined the relationship between the ex vivo valve thickness/calcification and in vivo clinical outcomes of Chinese patients with calcific AS. Six Chinese patients (3 patients with tricuspid aortic valves (TAV)) and 3 patients with. bicuspid aortic valves (BAV) with calcific AS undergoing heart valve replacement were initially chosen for this study. In vivo medical imaging of these calcific AS patients was evaluated using computed tomography and echocardiography. The ex vivo measurements including the actual thickness, calcified area and components of the calcified aortic values excised were performed by a digimatic caliper, X-ray equipment with a cellSens imaging analysis and portable Raman spectroscopy, respectively. Six patients were diagnosed with symptomatic moderate-to-severe AS. The thickness of noncoronary (N) leaflet in the excised TAV was significantly thicker than left-coronary (L) leaflet (p 0.05). The extent of calcification in the excised TAV was a statistically significant difference between N and L (p 0.05). The patients No. 1-3 were found to be TAV with partial commissural fusion. The patient No. 4 was classified as a type 1 NL-BAV morphotype, but both patients 5 and 6 were found to be true BAV (type 0 lateral-BAV). Each calcified valve leaflet was composed of apatites, proteins (collagen and proteoglycan), and a small amount of β-carotene and cholesterol after Raman spectral determination. The calcified nodules of each valve leaflet were predominately identified to be calcium hydroxyapatite and type-B carbonate apatite. However, octacalcium phosphate was also detected in the protein-rich part of calcified valve leaflets. A positive correlation was observed between thickness and calcification for both excised TAV and BAV after ex vivo examinations. Moreover, a negative relationship was obtained among in vivo AVA index, ex vivo

  20. FLUID MECHANICS OF ARTIFICIAL HEART VALVES

    OpenAIRE

    Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

    2009-01-01

    1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mecha...

  1. Human plasma-derived immunoglobulin G fractionated by an aqueous two-phase system, caprylic acid precipitation, and membrane chromatography has a high purity level and is free of detectable in vitro thrombogenic activity.

    Science.gov (United States)

    Vargas, M; Segura, Á; Wu, Y-W; Herrera, M; Chou, M-L; Villalta, M; León, G; Burnouf, T

    2015-02-01

    Instituto Clodomiro Picado has developed an immunoglobulin G (IgG) plasma fractionation process combining a polyethylene glycol/phosphate aqueous two-phase system (ATPS), caprylic acid precipitation and anion-exchange membrane chromatography. We evaluated the purity and in vitro thrombogenicity of such IgG, in line with current international requirements. Contributions of the different production steps to reduce thrombogenicity were assessed at 0·2 l-scale, and then the methodology was scaled-up to a 10 l-scale and final products (n = 3) were analysed. Purity, immunoglobulin composition, and subclass distribution were determined by electrophoretic and immunochemical methods. The in vitro thrombogenic potential was determined by a thrombin generation assay (TGA) using a Technothrombin fluorogenic substrate. Prekallikrein activator (PKA), plasmin, factor Xa, thrombin and thrombin-like activities were assessed using S-2302, S-2251, S-2222, S-2238 and S-2288 chromogenic substrates, respectively, and FXI by an ELISA. The thrombogenicity markers were reduced mostly during the ATPS step and were found to segregate mostly into the discarded liquid upper phase. The caprylic acid precipitation eliminated the residual procoagulant activity. The IgG preparations made from the 10 l-batches contained 100% gamma proteins, low residual IgA and undetectable IgM. The IgG subclass distribution was not substantially affected by the process. TGA and amidolytic activities revealed an undetectable in vitro thrombogenic risk and the absence of proteolytic enzymes in the final product. Fractionating human plasma by an ATPS combined with caprylic acid and membrane chromatography resulted in an IgG preparation of high purity and free of a detectable in vitro thrombogenic risk. © 2014 International Society of Blood Transfusion.

  2. Mitral valve surgery - open

    Science.gov (United States)

    ... be able to store blood in the blood bank for transfusions during and after your surgery. Ask ... stroke. Valves made from human or animal tissue fail over time. They have an average lifespan of ...

  3. Valve Repair or Replacement

    Science.gov (United States)

    ... valve surgery can be done using a robot. Robotic surgery does not require a large incision in the ... The Texas Heart Institute has a robot. With robotic surgery, the surgeon has a control console, a side ...

  4. Aortic Valve Regurgitation

    Science.gov (United States)

    ... valves. Rheumatic fever. Rheumatic fever — a complication of strep throat and once a common childhood illness in the ... a severe sore throat, see a doctor. Untreated strep throat can lead to rheumatic fever. Fortunately, strep throat ...

  5. Platelet activation of mechanical versus bioprosthetic heart valves during systole.

    Science.gov (United States)

    Hedayat, Mohammadali; Asgharzadeh, Hafez; Borazjani, Iman

    2017-05-03

    Thrombus formation is a major concern for recipients of mechanical heart valves (MHVs), which requires them to take anticoagulant drugs for the rest of their lives. Bioprosthetic heart valves (BHVs) do not require life-long anticoagulant therapy but deteriorate after 10-15years. The thrombus formation is initiated by the platelet activation which is thought to be mainly generated in MHVs by the flow through the hinge and the leakage flow during the diastole. However, our results show that the activation in the bulk flow during the systole phase might play an essential role as well. This is based on our results obtained by comparing the thrombogenic performance of a MHV and a BHV (as control) in terms of shear induced platelet activation under exactly the same conditions. Three different mathematical activation models including linear level of activation, damage accumulation, and Soares model are tested to quantify the platelet activation during systole using the previous simulations of the flow through MHV and BHV in a straight aorta under the same physiologic flow conditions. Results indicate that the platelet activation in the MHV at the beginning of the systole phase is slightly less than the BHV. However, at the end of the systole phase the platelet activation by the bulk flow for the MHV is several folds (1.41, 5.12, and 2.81 for linear level of activation, damage accumulation, and Soares model, respectively) higher than the BHV for all tested platelet activation models. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Echocardiographic anatomy of the mitral valve in healthy dogs and dogs with myxomatous mitral valve disease.

    Science.gov (United States)

    Wesselowski, S; Borgarelli, M; Menciotti, G; Abbott, J

    2015-06-01

    To further characterize the echocardiographic anatomy of the canine mitral valve apparatus in normal dogs and in dogs affected by myxomatous mitral valve disease (MMVD). Twenty-two normal dogs and 60 dogs with MMVD were prospectively studied. The length (AMVL), width (AMVW) and area (AMVA) of the anterior mitral valve leaflet were measured in the control group and the affected group, as were the diameters of the mitral valve annulus in diastole (MVAd) and systole (MVAs). The dogs with MMVD were staged based on American College of Veterinary Internal Medicine (ACVIM) guidelines and separated into groups B1 and B2/C. All measurements were indexed to body weight based on empirically defined allometric relationships. There was a statistically significant relationship between all log10 transformed mitral valve dimensions and body weight. The AMVL, AMVW, AMVA, MVAd and MVAs were all significantly greater in the B2/C group compared to the B1 and control groups. The AMVW was also significantly greater in the B1 group compared to the control group. Interobserver % coefficient of variation (% CV) was mitral valve leaflet and the mitral valve annulus in the dog can be indexed to body weight based on allometric relationships. Preliminary reference intervals have been proposed over a range of body sizes. Relative to normal dogs, AMVL, AMVW, AMVA, MVAd and MVAs are greater in patients with advanced MMVD. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Balloon expandable transcatheter heart valves for native mitral valve disease with severe mitral annular calcification.

    Science.gov (United States)

    Guerrero, Mayra; Urena, Marina; Pursnani, Amit; Wang, Dee D; Vahanian, Alec; O'Neill, William; Feldman, Ted; Himbert, Dominique

    2016-06-01

    Patients with mitral annular calcification (MAC) have high surgical risk for mitral valve replacement due to associated comorbidities and technical challenges related to calcium burden, precluding surgery in many patients. Transcatheter mitral valve replacement (TMVR) with the compassionate use of balloon expandable aortic transcatheter heart valves has been used in this clinical scenario. The purpose of this review was to summarize the early experience including successes and failures reported. TMVR might evolve into an acceptable alternative for selected patients with severe MAC who are not candidates for conventional mitral valve surgery. However, this field is at a very early stage and the progress will be significantly slower than the development of transcatheter aortic valve replacement due to the complexity of the mitral valve anatomy and its pathology. Optimizing patient selection process by using multimodality imaging tools to accurately measure the mitral valve annulus and evaluate the risk of left ventricular outflow tract obstruction is essential to minimize complications. Strategies for treating and preventing left ventricular outflow tract obstruction are being tested. Similarly, carefully selecting candidates avoiding patients at the end of their disease process, might improve the overall outcomes.

  8. Design Method for Fast Switching Seat Valves for Digital Displacement Machines

    DEFF Research Database (Denmark)

    Roemer, Daniel Beck; Johansen, Per; Pedersen, Henrik C.

    2014-01-01

    method for DD seat valves are presented, taking into account the significant aspects related to obtaining efficient DD valves with basis in a given DD machine specifications. The seat area is minimized and the stroke length is minimized to obtain fast switching times while considering the pressure loss...... of the valves. A coupled optimization is finally conducted to optimize the electro-magnetic actuator, leading to a valve design based on the chosen valve topology. The design method is applied to an example DD machine and the resulting valve design fulfilling the requirements is presented....

  9. Electromechanically Actuated Valve for Controlling Flow Rate

    Science.gov (United States)

    Patterson, Paul

    2007-01-01

    A proposed valve for controlling the rate of flow of a fluid would include an electric-motor-driven ball-screw mechanism for adjusting the seating element of the valve to any position between fully closed and fully open. The motor would be of a type that can be electronically controlled to rotate to a specified angular position and to rotate at a specified rate, and the ball screw would enable accurate linear positioning of the seating element as a function of angular position of the motor. Hence, the proposed valve would enable fine electronic control of the rate of flow and the rate of change of flow. The uniqueness of this valve lies in a high degree of integration of the actuation mechanism with the flow-control components into a single, relatively compact unit. A notable feature of this integration is that in addition to being a major part of the actuation mechanism, the ball screw would also be a flow-control component: the ball screw would be hollow so as to contain part of the main flow passage, and one end of the ball screw would be the main seating valve element. The relationships among the components of the valve are best understood by reference to the figure, which presents meridional cross sections of the valve in the fully closed and fully open positions. The motor would be supported by a bracket bolted to the valve body. By means of gears or pulleys and a timing belt, motor drive would be transmitted to a sleeve that would rotate on bearings in the valve body. A ball nut inside the sleeve would be made to rotate with the sleeve by use of a key. The ball screw would pass through and engage the ball nut. A key would prevent rotation of the ball screw in the valve body while allowing the ball screw to translate axially when driven by the ball nut. The outer surface of the ball screw would be threaded only in a mid-length region: the end regions of the outer surface of the ball screw would be polished so that they could act as dynamic sealing surfaces

  10. How Is Heart Valve Disease Treated?

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  11. How Is Heart Valve Disease Diagnosed?

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  12. When a Heart Murmur Signals Valve Disease

    Science.gov (United States)

    ... Order AHA Brochures Your Heart Valve Surgery Your Mitral Valve Prolapse Innocent Heart Murmurs If Your Child Has a Congenital Heart Defect See all of our brochures Valve Disease Resources Patient Guide: Understanding Your Heart Valve Problem | ...

  13. The living aortic valve: From molecules to function

    Science.gov (United States)

    Chester, Adrian H.; El-Hamamsy, Ismail; Butcher, Jonathan T.; Latif, Najma; Bertazzo, Sergio; Yacoub, Magdi H.

    2014-01-01

    The aortic valve lies in a unique hemodynamic environment, one characterized by a range of stresses (shear stress, bending forces, loading forces and strain) that vary in intensity and direction throughout the cardiac cycle. Yet, despite its changing environment, the aortic valve opens and closes over 100,000 times a day and, in the majority of human beings, will function normally over a lifespan of 70–90 years. Until relatively recently heart valves were considered passive structures that play no active role in the functioning of a valve, or in the maintenance of its integrity and durability. However, through clinical experience and basic research the aortic valve can now be characterized as a living, dynamic organ with the capacity to adapt to its complex mechanical and biomechanical environment through active and passive communication between its constituent parts. The clinical relevance of a living valve substitute in patients requiring aortic valve replacement has been confirmed. This highlights the importance of using tissue engineering to develop heart valve substitutes containing living cells which have the ability to assume the complex functioning of the native valve. PMID:25054122

  14. Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John; Brecker, Stephen

    2012-01-01

    Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry....

  15. An experimental method for validating compressor valve vibration theory

    NARCIS (Netherlands)

    Habing, R.A.; Peters, M.C.A.M.

    2006-01-01

    This paper presents an experimental method for validating traditional compressor valve theory for unsteady flow conditions. Traditional valve theory considers the flow force acting on the plate and the flow rate as quasi-steady variables. These variables are related via semi-empirical coefficients

  16. Performance characteristics of a gelled-electrolyte valve-regulated ...

    Indian Academy of Sciences (India)

    12 V/25 AH gelled-electrolyte valve-regulated lead-acid batteries have been assembled in-house and their performance studied in relation to the absorptive glass-microfibre valve-regulated and flooded-electrolyte counterparts at various discharge rates and temperatures between –40°C and 40°C. Although the ...

  17. Interlayer reliant magnetotransport in graphene spin valve

    Science.gov (United States)

    Iqbal, Muhammad Zahir; Hussain, Ghulam; Siddique, Salma; Iqbal, Muhammad Waqas

    2017-11-01

    Here the magnetotransport properties of vertical spin valve structures incorporating graphene (Gr), Gr/Au and Gr/Al2O3 intervening layers are elucidated. An in-plane magnetic field is obliquely applied to the device with the purpose to vary the relative magnetizations of ferromagnetic electrodes (Co and Ni). The relative magnetoresistance (MR) of Co/Gr/Ni is enhanced from ∼0.16% to 0.57% by simply passivating the bottom Ni electrode with thin Au film. On the other hand, depositing Al2O3 on the bottom ferromagnetic layer in such a spin valve junction not only increases the magnitude of MR (∼-0.52%) but also reverses its polarity. Furthermore, the linear current-voltage characteristics for graphene and graphene/Au spin valve devices specifies ohmic contact, while non-linear curves indicate tunneling behavior for graphene/Al2O3 device.

  18. Retrieval analysis of mechanical heart valves: impact on design and clinical practice

    NARCIS (Netherlands)

    Cromheecke, M. E.; Overkamp, P. J.; de Mol, B. A.; van Gaalen, G. L.; Becker, A. E.

    1998-01-01

    Explanted mechanical heart valves were examined nondestructively, and the findings were related to guidelines, technical reports, and other information to judge the risk of failure and its possible impact on valve design and clinical practice. Diagnoses for single valves could be made, but risks and

  19. Use of a novel hybrid approach to salvage an attempted transcatheter pulmonary valve implant.

    Science.gov (United States)

    Berman, Darren P; Burke, Redmond; Zahn, Evan M

    2012-06-01

    Transcatheter pulmonary valve implantation in the setting of right ventricle-to-pulmonary artery conduit dysfunction is a relatively new procedure with encouraging early and midterm results. Malpositioning of the valve during implantation is a potentially serious complication. This report describes a case in which valve malpositioning was avoided by the use of a unique hybrid approach. This approach may prove to be useful for a select group of patients requiring pulmonary valve replacement.

  20. Effect of transcatheter aortic valve size and position on valve-in-valve hemodynamics: An in vitro study.

    Science.gov (United States)

    Azadani, Ali N; Reardon, Michael; Simonato, Matheus; Aldea, Gabriel; Nickenig, Georg; Kornowski, Ran; Dvir, Danny

    2017-06-01

    Transcatheter heart valve implantation in failed aortic bioprostheses (valve-in-valve [ViV]) is an increasingly used therapeutic option for high-risk patients. However, high postprocedural gradients are a significant limitation of aortic ViV. Our objective was to evaluate Medtronic CoreValve Evolut R ViV hemodynamics in relation to the degree of device oversizing and depth of implantation. Evolut R devices of 23 and 26 mm were implanted within 21-, 23-, and 25-mm Hancock II bioprostheses. Small and gradual changes in implantation depth were attempted. Hemodynamic testing was performed in a pulse duplicator under ISO-5840 standard. A total of 47 bench-testing experiments were performed. The mean gradient of the 26-mm Evolut R in 23- and 25-mm Hancock II was lower than 23-mm Evolut R (P  17.5 mm. The current comprehensive bench-testing assessment demonstrates the importance of both transcatheter heart valve size and device position for the attainment of optimal hemodynamics during ViV procedures. Additional in vitro testing may be required to develop hemodynamics-based guidelines for device sizing in ViV procedures in degenerated surgical bioprostheses. Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  1. Safety valve for offshore borehole

    Energy Technology Data Exchange (ETDEWEB)

    McGill, H.L.; Randermann, E. Jr.; Musik, O.J.

    1977-10-06

    The invention concerns a new and improved submarine safety valve with a valve element which rotate, which can be used, in emergencies, to separate the wound-up piping which extends into the borehole and to close the production line.

  2. Diseases of the Tricuspid Valve

    Science.gov (United States)

    ... diseases of the tricuspid valve are regurgitation and stenosis. Tricuspid Regurgitation Tricuspid regurgitation is also called tricuspid ... the tricuspid valve may also be needed. Tricuspid Stenosis Tricuspid stenosis is a narrowing or blockage of ...

  3. Options for Heart Valve Replacement

    Science.gov (United States)

    ... valve: Aortic regurgitation , (sometimes referred to as aortic insufficiency) is another common valve problem that may require ... allows oxygenated blood to flow backwards into the lungs instead of continuing through the heart as it ...

  4. Variable Valve Actuation

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Gutterman; A. J. Lasley

    2008-08-31

    Many approaches exist to enable advanced mode, low temperature combustion systems for diesel engines - such as premixed charge compression ignition (PCCI), Homogeneous Charge Compression Ignition (HCCI) or other HCCI-like combustion modes. The fuel properties and the quantity, distribution and temperature profile of air, fuel and residual fraction in the cylinder can have a marked effect on the heat release rate and combustion phasing. Figure 1 shows that a systems approach is required for HCCI-like combustion. While the exact requirements remain unclear (and will vary depending on fuel, engine size and application), some form of substantially variable valve actuation is a likely element in such a system. Variable valve actuation, for both intake and exhaust valve events, is a potent tool for controlling the parameters that are critical to HCCI-like combustion and expanding its operational range. Additionally, VVA can be used to optimize the combustion process as well as exhaust temperatures and impact the after treatment system requirements and its associated cost. Delphi Corporation has major manufacturing and product development and applied R&D expertise in the valve train area. Historical R&D experience includes the development of fully variable electro-hydraulic valve train on research engines as well as several generations of mechanical VVA for gasoline systems. This experience has enabled us to evaluate various implementations and determine the strengths and weaknesses of each. While a fully variable electro-hydraulic valve train system might be the 'ideal' solution technically for maximum flexibility in the timing and control of the valve events, its complexity, associated costs, and high power consumption make its implementation on low cost high volume applications unlikely. Conversely, a simple mechanical system might be a low cost solution but not deliver the flexibility required for HCCI operation. After modeling more than 200 variations of

  5. Echocardiography of the mitral valve

    OpenAIRE

    Omran, A.S.; Arifi, A.A.; Mohamed, A.A.

    2010-01-01

    Mitral valve disease is the second most common valvular heart disease after the aortic valve worldwide. Mitral valve has historically been a structure of interest by pioneers in echocardiography. One of the earliest applications of echocardiography was in the diagnosis of valvular heart disease, particularly mitral stenosis. In this review we wish to take the reader through the structural and hemodynamic evaluation of the normal mitral valve.

  6. Valve thrombosis following transcatheter aortic valve implantation: a systematic review.

    Science.gov (United States)

    Córdoba-Soriano, Juan G; Puri, Rishi; Amat-Santos, Ignacio; Ribeiro, Henrique B; Abdul-Jawad Altisent, Omar; del Trigo, María; Paradis, Jean-Michel; Dumont, Eric; Urena, Marina; Rodés-Cabau, Josep

    2015-03-01

    Despite the rapid global uptake of transcatheter aortic valve implantation, valve trombosis has yet to be systematically evaluated in this field. The aim of this study was to determine the clinical characteristics, diagnostic criteria, and treatment outcomes of patients diagnosed with valve thrombosis following transcatheter aortic valve implantation through a systematic review of published data. Literature published between 2002 and 2012 on valve thrombosis as a complication of transcatheter aortic valve implantation was identified through a systematic electronic search. A total of 11 publications were identified, describing 16 patients (mean age, 80 [5] years, 65% men). All but 1 patient (94%) received a balloon-expandable valve. All patients received dual antiplatelet therapy immediately following the procedure and continued to take either mono- or dual antiplatelet therapy at the time of valve thrombosis diagnosis. Valve thrombosis was diagnosed at a median of 6 months post-procedure, with progressive dyspnea being the most common symptom. A significant increase in transvalvular gradient (from 10 [4] to 40 [12] mmHg) was the most common echocardiographic feature, in addition to leaflet thickening. Thrombus was not directly visualized with echocardiography. Three patients underwent valve explantation, and the remaining received warfarin, which effectively restored the mean transvalvular gradient to baseline within 2 months. Systemic embolism was not a feature of valve thrombosis post-transcatheter aortic valve implantation. Although a rare, yet likely under-reported complication of post-transcatheter aortic valve implantation, progressive dyspnea coupled with an increasing transvalvular gradient on echocardiography within the months following the intervention likely signifies valve thrombosis. While direct thrombus visualization appears difficult, prompt initiation of oral anticoagulation therapy effectively restores baseline valve function. Copyright © 2014

  7. Building valve amplifiers

    CERN Document Server

    Jones, Morgan

    2013-01-01

    Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or

  8. Danfos: Thermostatic Radiator Valves

    DEFF Research Database (Denmark)

    Gregersen, Niels; Oliver, James; Hjorth, Poul G.

    2000-01-01

    This problem deals with modelling the flow through a typical Danfoss thermostatic radiator valve.Danfoss is able to employ Computational Fluid Dynamics (CFD) in calculations of the capacity of valves, but an experienced engineer can often by rules of thumb "guess" the capacity, with a precision...... similar to the one achieved by the expensive and time-consuming CFD calculations. So CFD is only used in case of entirely new designs or where a very detailed knowledge of the flow is required. Even though rules of thumb are useful for those, who have developed them, Danfoss needs an objective and general...

  9. SAFETY SHUTOFF VALVE

    DEFF Research Database (Denmark)

    2010-01-01

    resulted from collision or effusion. A static tower has been applied for the main core of this part of the valve which loses balance state under the effect of collision and bounces to the neighboring part, which results in release of the catch and blockage of the gas passing channel.......It is disclosed a shut-off valve which acts automatically and has a fully mechanical performance with respect to the loosing of the tower-shape part balance under the effect of the special acceleration Which is arisen from the quakes waves or serious vibrations, while such vibrations are mainly...

  10. Edwards SAPIEN 3 valve.

    Science.gov (United States)

    Binder, Ronald K; Rodés-Cabau, Josep; Wood, David A; Webb, John G

    2012-09-01

    Building on the established success with the SAPIEN, SAPIEN XT and earlier prototypic transcatheter heart valves (THV) the newest balloon-expandable valve incorporates a number of new and enhanced features intended to reduce the risk of vascular injury, to reduce paravalvular regurgitation, and to facilitate rapid and accurate positioning and implantation. The SAPIEN 3 THV incorporates a cobalt chromium stent, bovine pericardial leaflets, and both an inner and new outer polyethylene terephthalate sealing cuff. The delivery system incorporates an active three-dimensional coaxial positioning catheter, and is compatible with a 14 Fr expandable sheath.

  11. Noncontacting valve-position indicator

    Science.gov (United States)

    Crovella, E. A.; Cummins, R. D.; Wada, J. M.

    1979-01-01

    Position of sealed valve or other movable part is indicated without penetrating housing. Flux from magnets connected to stem of hydraulic valve penetrates pressure wall and is sensed by Hall-effect transducer outside wall. When valve closes, moving stem and magnets, voltage from transducer decreases; thus, stem position is indicated without physical contact.

  12. Radiological findings of congenital urethral valves

    Energy Technology Data Exchange (ETDEWEB)

    Yeon, Kyung Mo; Kook, Shin Ho [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1990-12-15

    Congenital urethral valve is the common cause of hydronephrosis in newborn infants and the most common cause of bladder outlet obstruction in male children. We reviewed and analysed radiological findings and associated anomalies of 16 cases of congenital urethral valve which were examined during the period from January 1985 to December 1989. The most frequent age was under one year old (56%). The main symptoms were urinary dribbing (37.5%), weak stream (25%) and urinary frequency and incontinence (25%). Anterior urethral valve (AUV) was 5 cases (31%) and posterior urethral valve (PUV) was 11 cases(69%), in which 10 cases were Type I and one case was Type III. Bladder wall thickening was seen in all cases and its severity was partly correlated with the degree of vesicoureteral reflux (VUR). VUR was observed in 12 cases (75%), and relatively severe in older age group. The degree of VUR was milder in AUV than PUV. Hydronephrosis was more severe in PUV than in anterior one, and its degree was correlated with the severity of VUR. Associated anomalies were ectopic urethral opening (2 cases), PDA (1 case), congenital megacolon (1 case) and patent urachus (1 case) in PUV. So early diagnosis and treatment of congenital urethral valve is essential to the prevention of renal damage.

  13. Predictors of permanent pacemaker implantation after transfemoral aortic valve implantation with the Lotus valve.

    Science.gov (United States)

    Keßler, Mirjam; Gonska, Birgid; Seeger, Julia; Rottbauer, Wolfgang; Wöhrle, Jochen

    2017-10-01

    Permanent pacemaker implantation (PPMI) after transcatheter aortic valve implantation is of high clinical relevance, but PPMI rates differ widely between valve types. Although the Lotus valve can be repositioned, reported rates for PPMI are high. The predictors of PPMI after Lotus valve implantation have not been defined yet. We analyzed the impact of preexisting conduction disturbances, depth of implantation, oversizing, and amount of calcification on PPMI in 216 patients with severe symptomatic aortic stenosis underdoing Lotus valve implantation. PPMI was required in 39.8% of patients. Patients with need for PPMI compared with patients without need for PPMI had more often the following criteria: male gender (P=.035); preprocedural right bundle-branch block (RBBB) (16.3% vs 0, P<.001); atrioventricular (AV) block first degree (26.7% vs 10.1%, P=.004); higher calcium volume of the left coronary cusp (63.1±87.5 mm(3) vs 42.8±49.3 mm(3), P=.05); and deeper valve implantation at right coronary (P=.011), noncoronary (P=.026), and left coronary (P=.012) position. Oversizing in relation to annulus and left ventricular outflow tract did not have an impact on need for PPMI. By multiple regression analysis, preprocedural AV block first degree (P=.005), RBBB (P<.001), and depth of implantation (P=.006) were independent risk factors for need of PPMI. In patients with severe aortic stenosis receiving transfemoral Lotus valve, preexisting AV block first degree, RBBB, and implantation depth are independent predictors of PPMI, highlighting the importance of careful valve positioning. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Characterization of Aortic Valve Closure Artifact During Outflow Tract Mapping: Correlation With Hemodynamics and Mechanical Valves.

    Science.gov (United States)

    Romero, Jorge; Ajijola, Olujimi; Shivkumar, Kalyanam; Tung, Roderick

    2017-06-01

    Premature ventricular contractions originating in the left ventricle outflow tract represent a significant subgroup of patients referred for catheter ablation. Mechanical artifacts from aortic valve leaflet motion may be observed during mapping, although the incidence and characteristics have not been reported. Twenty-eight consecutive patients with left ventricle outflow tract premature ventricular contraction were included. Electric signals recorded on the ablation catheter not coincident with atrial or ventricular depolarization were analyzed on the recording system. Correlation with invasive hemodynamic aortic pressure tracings was performed. Additionally, 4 patients with mechanical aortic valves, who underwent scar-related ventricular tachycardia ablation, were analyzed to correlate the timing of the observed artifacts with native aortic valves. Aortic valve artifact was observed while mapping within the coronary cusps in 11 patients (39%; 73% men; age, 41±25 years; left ventricular ejection fraction 49±16%) with high incidence from the left coronary cusp. This artifact was consistently observed with timing coincident with the terminal portion of the T wave. The average interval between the end of the T wave and the aortic valve artifact was 19±37 ms. The duration of the aortic valve artifact was 39±8 ms with amplitude of 0.12±0.07 mV (range, 0.06-0.36 mV). In patients referred for left ventricle outflow tract premature ventricular contraction ablation, an aortic valve closure artifact is observed in up to one third of cases during mapping within the aortic cusps. The timing of this artifact correlates with invasive hemodynamics and mechanical aortic valve artifacts. Recognition of this physiological phenomenon is useful when assigning near-field activation. © 2017 American Heart Association, Inc.

  15. Tricuspid valve and percutaneous approach: No longer the forgotten valve!

    Science.gov (United States)

    Bouleti, Claire; Juliard, Jean-Michel; Himbert, Dominique; Iung, Bernard; Brochet, Eric; Urena, Marina; Dilly, Marie-Pierre; Ou, Phalla; Nataf, Patrick; Vahanian, Alec

    2016-01-01

    Tricuspid valve disease is mainly represented by tricuspid regurgitation (TR), which is a predictor of poor outcome. TR is usually secondary, caused by right ventricle pressure or volume overload, the leading cause being left-sided heart valve diseases. Tricuspid surgery for severe TR is recommended during left valve surgery, and consists of either a valve replacement or, most often, a tricuspid repair with or without prosthetic annuloplasty. When TR persists or worsens after left valvular surgery, redo isolated tricuspid surgery is associated with high mortality. In addition, a sizeable proportion of patients present with tricuspid surgery deterioration over time, and need a reintervention, which is associated with high morbi-mortality rates. In this context, and given the recent major breakthrough in the percutaneous treatment of aortic and mitral valve diseases, the tricuspid valve appears an appealing challenge, although it raises specific issues. The first applications of transcatheter techniques for tricuspid valve disease were valve-in-valve and valve-in-ring implantation for degenerated bioprosthesis or ring annuloplasty. Some concerns remain regarding prosthesis sizing, rapid ventricular pacing and the best approach, but these procedures appear to be safe and effective. More recently, bicuspidization using a transcatheter approach for the treatment of native tricuspid valve has been published, in two patients. Finally, other devices are in preclinical development. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  16. Clinical outcomes in 1731 patients undergoing mitral valve surgery for rheumatic valve disease.

    Science.gov (United States)

    Kim, Wan Kee; Kim, Ho Jin; Kim, Joon Bum; Jung, Sung-Ho; Choo, Suk Jung; Chung, Cheol Hyun; Lee, Jae Won

    2017-11-16

    Unlike degenerative mitral valve (MV) disease, the advantages of valve repair procedure over replacement have been debated in rheumatic MV disease. This study aims to evaluate the impact of procedural types on long-term outcomes through analyses on a large data set from an endemic area of rheumatic disease. We evaluated 1731 consecutive patients (52.3±12.5 years; 1190 women) undergoing MV surgery for rheumatic MV disease between 1997 and 2015. Long-term survival and valve-related outcomes were compared between repair and replacement procedures. To adjust for selection bias, propensity score analyses were performed. Patients undergoing repair were younger and had more predominant mitral regurgitation than mechanical and bioprosthetic replacement groups (61.6% vs 15.6% vs 24.4%; Pvalve-related complications. Propensity score matching yielded 188 pairs of repair and replacement patients that were well balanced for baseline covariates. In the matched cohort, there was no significant difference in the mortality risk between the repair and replacement groups (HR, 1.24; 95% CI 0.62 to 2.48). The risk of composite valve-related complications, however, was significantly lower in repair group (HR, 0.57; 95% CI 0.33 to 0.99) principally derived by a lower risk of haemorrhagic events (HR, 0.23; 95% CI 0.07 to 0.70). The incidence of reoperation was not significantly different between groups in the matched cohort (HR, 1.62; 95% CI 0.49 to 5.28). Valve repair in well-selected patients with severe rheumatic MV disease led to comparable survival, but superior valve-related outcomes compared with valve replacement surgery. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  17. Multimodality Imaging of Heart Valve Disease

    Energy Technology Data Exchange (ETDEWEB)

    Rajani, Ronak, E-mail: Dr.R.Rajani@gmail.com [Department of Cardiology, St. Thomas’ Hospital, London (United Kingdom); Khattar, Rajdeep [Department of Cardiology, Royal Brompton Hospital, London (United Kingdom); Chiribiri, Amedeo [Divisions of Imaging Sciences, The Rayne Institute, St. Thomas' Hospital, London (United Kingdom); Victor, Kelly; Chambers, John [Department of Cardiology, St. Thomas’ Hospital, London (United Kingdom)

    2014-09-15

    Unidentified heart valve disease is associated with a significant morbidity and mortality. It has therefore become important to accurately identify, assess and monitor patients with this condition in order that appropriate and timely intervention can occur. Although echocardiography has emerged as the predominant imaging modality for this purpose, recent advances in cardiac magnetic resonance and cardiac computed tomography indicate that they may have an important contribution to make. The current review describes the assessment of regurgitant and stenotic heart valves by multimodality imaging (echocardiography, cardiac computed tomography and cardiac magnetic resonance) and discusses their relative strengths and weaknesses.

  18. Relation of coarctation of the aorta to the occurrence of ascending aortic dilation in children and young adults with bicuspid aortic valves.

    Science.gov (United States)

    Beaton, Andrea Z; Nguyen, Thieu; Lai, Wyman W; Chatterjee, Samprit; Ramaswamy, Prema; Lytrivi, Irene D; Parness, Ira A; Srivastava, Shubhika

    2009-01-15

    Children with bicuspid aortic valve (BAV) have aortic dilation that is present and progressive from birth irrespective of the functional state of the valve. There are no published data comparing aortic dilation in children with BAV with and without aortic coarctation (CoA). The objectives of this study were to (1) compare differences in aortic dimensions and rates of dilation between children with isolated BAV with those of children with BAV and CoA and (2) identify risk factors for the development of aortic dilation. Patients with BAV with CoA (group A) and without CoA (group B) were identified from our echocardiographic database (1993 to 2006). Aortic measurements at 4 levels were obtained, and z scores were compared. Criteria for exclusion were severe aortic regurgitation/stenosis, previous aortic valvuloplasty, complex left-sided cardiac disease, ventricular septal defects, and Turner, Noonan, Williams, and Marfan syndromes. There were 600 echocardiograms in 247 patients. Group A had 192 echocardiograms in 53 patients (median age 11.3 years; range 0 to 30; median follow-up 7 years), and group B had 382 in 194 patients (median age 8.7 years; range 0 to 29; median follow-up 4 years). Group B had significantly greater ascending aorta dimensions (paortic dilation (paortic dimensions.

  19. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, Jordan [Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States); Ansanelli, Eric [Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States)

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.

  20. Aortic valve surgery - open

    Science.gov (United States)

    ... be able to store blood in the blood bank for transfusions during and after your surgery. Ask ... Mechanical heart valves do not fail often. However, blood clots can develop on them. If a blood clot forms, you may have a stroke. Bleeding can occur, ...

  1. Early experience with the Venus p‑valve for percutaneous pulmonary valve implantation in native outflow tract.

    Science.gov (United States)

    Garay, F; Pan, X; Zhang, Y J; Wang, C; Springmuller, D

    2017-02-01

    The Venus p‑valve (MedTech, Shanghai, China) is a self-expanding percutaneous heart valve designed to be implanted in a native patched right ventricle outflow tract. The worldwide clinical experience with this valve is just beginning and the results have so far been encouraging. We present our initial early experience implanting the Venus p‑valve in the native right ventricle outflow tract of patients with Tetralogy of Fallot repaired with a transannular patch. In 10 selected patients a procedure for percutaneous pulmonary valve implantation was performed using the Venus p‑valve. The patients mean age was 32 years (13-57), mean weight 59.6 kg (40-80). All patients had Tetralogy of Fallot with moderate to severe pulmonary regurgitation and an indication for pulmonary valve replacement. The implantation procedure was successful in all the patients resulting in an immediately functional valve. No procedure-related complications were observed. Follow-up after 12 months (4-21) resulted in an improvement in NYHA class. There was a reduction of the mean right ventricle diastolic volume from 139 ml/m2 (105-179) to 78 ml/m2 (65-100) and improvement in the regurgitation fraction from 42% (29-58) to 1% (0-5), as seen on routine cardiac magnetic resonance 6 months after the implantation. No stent fractures have been observed so far. Percutaneous pulmonary valve implantation with the Venus p‑valve resulted in a safe and effective procedure. The valve has predictable and sustained functional competence, resulting in clinical improvement in the patients.

  2. Diaphragms in air-operated valves

    Energy Technology Data Exchange (ETDEWEB)

    Groeger, J.E.

    1996-12-01

    The author will present current issues related to diaphgrams in air-operated valves. Altran Materials Engineering, Inc., often performs root-cause analyses for nuclear power plant owners. The author will discuss various analyses that have been performed or are currently underway.

  3. Autopsy after transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

    van Kesteren, F; Wiegerinck, E M A; Rizzo, S

    2017-01-01

    Autopsy after transcatheter aortic valve implantation (TAVI) is a new field of interest in cardiovascular pathology. To identify the cause of death, it is important to be familiar with specific findings related to the time interval between the procedure and death. We aimed to provide an overview ...

  4. Measurement of reed valve kinematics

    Directory of Open Access Journals (Sweden)

    Fenkl Michael

    2016-01-01

    Full Text Available The measurement of key kinematic parameters of a reed valve movement is necessary for the further development of the reed valve system. These parameters are dependent on the geometry and material properties of the valve. As they directly affect the quantity of air flowing around the valve, a simple and easy to implement measurement of various valve configuration based on the air flow has been devised and is described in this paper, along with its technical parameters and drawbacks when evaluating reed valves used in reciprocating air compressors. Results are presented for a specimen of a compressor under examination. All kinematic parameters, and timing of the opening and closing of the valve, obtained from the measurement are presented and discussed.

  5. Joint hypermobility syndrome and mitral valve prolapse in panic disorder.

    Science.gov (United States)

    Gulpek, Demet; Bayraktar, Erhan; Akbay, Sebnem Pirildar; Capaci, Kazým; Kayikcioglu, Meral; Aliyev, Emil; Soydas, Cahide

    2004-09-01

    The purpose of this study is to test the association between joint hypermobility syndrome (JHS) and panic disorder (PD) and to determine whether mitral valve prolapse (MVP) modifies or accounts in part for the association. A total of 115 subjects are included in this study in three groups. Group I (n = 42): panic disorder patients with MVP. Group II (n = 35): panic disorder patients without mitral valve prolapse. Group III (n = 38): control subjects who had mitral valve prolapse without any psychiatric illness. Beighton criteria were used to assess joint hypermobility syndrome. Two-dimensional and M-mode echocardiography was performed on each subject to detect mitral valve prolapse. Joint hypermobility syndrome was found in 59.5% of panic disorder patients with mitral valve prolapse, in 42.9% of patients without mitral valve prolapse and in 52.6% of control subjects. Beighton scores was 4.93 +/- 2.97 in group I, 4.09 +/- 2.33 in group II, and 4.08 +/- 2.34 in group III. There was no significant difference between groups according to Beighton scores. We did not detect a statistically significant relationship between panic disorder and joint hypermobility syndrome. Mitral valve prolapse and joint hypermobility syndrome are known to be etiologically related and we suggest that mitral valve prolapse affects the prevalence of joint hypermobility syndrome in the panic disorder patients.

  6. Midterm Results of Aortic Valve Replacement with Cryopreserved Homografts

    Directory of Open Access Journals (Sweden)

    Emre Özker

    2012-06-01

    Full Text Available Objective: The aim of this study was to analyze the midterm clinical results of aortic valve replacement with cryopreserved homografts.Materials and Methods: Aortic valve replacement was performed in 40 patients with cryopreserved homograft. The indications were aortic valve endocarditis in 20 patients (50%, truncus arteriosus in 6 patients (15%, and re-stenosis or regurtitation after aortic valve reconstruction in 14 (35% patients. The valve sizes ranged from 10 to 27mm. A full root replacement technique was used for homograft replacement in all patients.Results: The 30-day postoperative mortality rate was 12.5% (5 patients. There were four late deaths. Only one of them was related to cardiac events. Overall mortality was 22.5%. Thirty-three patients were followed up for 67±26 months. Two patients needed reoperation due to aortic aneurysm caused by endocarditis. The mean transvalvular gradient significantly decreased after valve replacement (p<0.003. The last follow up showed that the 27 (82% patients had a normal left ventricular function.Conclusion: Cryopreserved homografts are safe alternatives to mechanical valves that can be used when there are proper indications. Although it has a high perioperative mortality rate, cryopreserved homograft implantation is an alternative for valve replacement, particularly in younger patients and for complex surgical problems such as endocarditis that must be minimalized.

  7. Minimising life cycle costs of automated valves in offshore platforms

    Energy Technology Data Exchange (ETDEWEB)

    Yli-Petays, Juha [Metso Automation do Brasil Ltda., Rio de Janeiro, RJ (Brazil); Niemela, Ismo [Metso Automation, Imatra (Finland)

    2012-07-01

    Automated process valves play an essential role in offshore platforms operation. If you are able to optimize their operation and maintenance activities you can receive extensive operational savings with minimal investment. Valves used in offshore platforms doesn't differentiate that much from the valves used in downstream but there are certain specialties, which makes the operations more challenging in offshore: Process valves are more difficult to access and maintain because of space limitations. Also spare part inventories and deliveries are challenging because of offshore platform's remote location. To overcome these challenges usage of digital positioners with diagnostic features has become more common because predictive maintenance capabilities enable possibilities to plan the maintenance activities and this way optimise the spare part orders regarding to valves. There are intelligent controllers available for control valves, automated on/off valves as well as ESD-valves and whole network of automated valves on platforms can be controlled by intelligent valve controllers. This creates many new opportunities in regards of optimized process performance or predictive maintenance point-of-view. By means of intelligent valve controllers and predictive diagnostics, condition monitoring and maintenance planning can also be performed remotely from an onshore location. Thus, intelligent valve controllers provide good way to minimize spending related to total cost of ownership of automated process valves. When purchase value of control valve represent 20% of TCO, intelligent positioner and predictive maintenance methods can enable as high as 30% savings over the life cycle of asset so basically it benefit savings higher than whole investment of monitored asset over its life cycle. This is mainly achieved through the optimized maintenance activities since real life examples has shown that with time based maintenance (preventive maintenance) approach 70% of

  8. Micro-valve pump light valve display

    Science.gov (United States)

    Lee, Yee-Chun

    1993-01-01

    A flat panel display incorporates a plurality of micro-pump light valves (MLV's) to form pixels for recreating an image. Each MLV consists of a dielectric drop sandwiched between substrates, at least one of which is transparent, a holding electrode for maintaining the drop outside a viewing area, and a switching electrode from accelerating the drop from a location within the holding electrode to a location within the viewing area. The sustrates may further define non-wetting surface areas to create potential energy barriers to assist in controlling movement of the drop. The forces acting on the drop are quadratic in nature to provide a nonlinear response for increased image contrast. A crossed electrode structure can be used to activate the pixels whereby a large flat panel display is formed without active driver components at each pixel.

  9. When operable patients become inoperable: conversion of a surgical aortic valve replacement into transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

    Olsen, Lene Kjaer; Arendrup, Henrik; Engstrøm, Thomas

    2009-01-01

    Transcatheter aortic valve implantation (TAVI) is a relatively new treatment option for inoperable patients with severe aortic stenosis (AS). This case describes how a planned conventional surgical aortic valve replacement (AVR) on a 73-year-old woman was successfully converted to a TAVI procedure....... On extracorporal circulation it was reconized that the aortic annulus, the coronary ostiae and the proximal part of the ascending aorta were severely calcified making valve implantation impossible. Surgical closure without valve substitution was estimated to be associated with a high risk of mortality due......, and the prosthesis was sutured to the ascending aorta. With some manipulation of the prosthesis it was possible to suture the aorta circumferentially around the fully expanded upper part of the prosthesis. Post-procedurally the patient recovered successfully, with improved function capacity, aortic valve area...

  10. Age-dependent decreases of calcium, phosphorus, sulfur, and zinc in the cardiac valves of monkeys.

    Science.gov (United States)

    Menetti, Federico; Tohno, Setsuko; Tohno, Yoshiyuki; Azuma, Cho; Moriwake, Yumi; Satoh, Hiroyasu; Minami, Takeshi; Mahakkanukrauh, Pasuk; Oishi, Takao; Hayashi, Motoharu

    2005-09-01

    To elucidate compositional changes of the cardiac valves in monkey with aging, the authors investigated age-related changes of elements in the four cardiac valves of rhesus and Japanese monkeys and the relationships among elements by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The four cardiac valves of the aortic, pulmonary, mitral, and tricuspid valves were resected from 19 rhesus and 11 Japanese monkeys, ranging in age from 10 d to 33 yr. The element contents were determined by ICP-AES. It was found that the Ca, P, S, and Zn contents were high in the four cardiac valves of the monkeys below 1 yr and thereafter decreased significantly with aging, except for Ca in the mitral valve, for which no significant correlation was found between age and Ca content. The Ca and P contents did not increase in the four cardiac valves at old age. This result revealed that calcification scarcely occurred in the four cardiac valves at old age. With regard to the relationships among elements, it was found that there were significant direct correlations among the Ca, P, S, and Zn contents in all of the four cardiac valves of the monkeys, with two exceptions between P and Zn contents in both the aortic and pulmonary valves. Therefore, as Ca decreased in the four cardiac valves, P, S, and Zn decreased simultaneously in the same cardiac valves.

  11. Cyclonic valve test: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, Andre Sampaio; Moraes, Carlos Alberto C.; Marins, Luiz Philipe M.; Soares, Fabricio; Oliveira, Dennis; Lima, Fabio Soares de; Airao, Vinicius [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Ton, Tijmen [Twister BV, Rijswijk (Netherlands)

    2012-07-01

    For many years, the petroleum industry has been developing a valve that input less shear to the flow for a given required pressure drop and this can be done using the cyclonic concept. This paper presents a comparison between the performances of a cyclonic valve (low shear) and a conventional globe valve. The aim of this work is to show the advantages of using a cyclonic low shear valve instead of the commonly used in the primary separation process by PETROBRAS. Tests were performed at PETROBRAS Experimental Center (NUEX) in Aracaju/SE varying some parameters: water cut; pressure loss (from 4 kgf/cm2 to 10 kgf/cm2); flow rates (30 m3/h and 45 m3/h). Results indicates a better performance of the cyclonic valve, if compared with a conventional one, and also that the difference of the performance, is a function of several parameters (emulsion stability, water content free, and oil properties). The cyclonic valve tested can be applied as a choke valve, as a valve between separation stages (for pressure drop), or for controlling the level of vessels. We must emphasize the importance to avoid the high shear imposed by conventional valves, because once the emulsion is created, it becomes more difficult to break it. New tests are being planned to occur in 2012, but PETROBRAS is also analyzing real cases where the applications could increase the primary process efficiency. In the same way, the future installations are also being designed considering the cyclonic valve usage. (author)

  12. First Reported Successful Femoral Valve-in-Valve Transcatheter Aortic Valve Replacement Using the Edwards Sapien 3 Valve.

    Science.gov (United States)

    Fournier, Stephane; Monney, Pierre; Roguelov, Christan; Zuffi, Andrea; Iglesias, Juan F; Qanadli, Salah D; Courbon, Cecile; Eeckhout, Eric; Muller, Olivier

    2015-10-01

    Management of degenerated aortic valve bioprosthesis classically requires redo surgery, but transcatheter aortic valve-in-valve implantation is becoming a valid alternative in selected cases. In the case of a degenerated Mitroflow bioprosthesis, TAVR is associated with an additional challenge due to a specific risk of coronary occlusion. We aimed to assess the safety and feasibility of transfemoral valve-in-valve implantation of the new Edwards Sapien 3 (Edwards Lifesciences) in a degenerated Mitroflow bioprosthesis (Sorin Group, Inc). We report here the safety and feasibility of transfemoral valve-in-valve implantation of a 23 mm Edwards Sapien 3 in a degenerated 25 mm Mitroflow valve and describe the specific assessment of the risk of coronary obstruction using a multi-imaging modality. The final result showed an absence of aortic regurgitation and a mean transvalvular gradient of 14 mm Hg. The patient had no major adverse cardiovascular events at 30-day follow-up. Transcatheter valve-in-valve implantation of an Edwards Sapien 3 in a degenerated Mitroflow is feasible and safe, considering a careful assessment of the risk of coronary obstruction with Mitroflow bioprosthesis due to leaflets mounted externally to the stent.

  13. Mechanical Valve Replacement: Early Results

    Directory of Open Access Journals (Sweden)

    Habib Cakir

    2012-02-01

    Full Text Available Aim: Valve diseases in developing countries like Turkey which often occur as a complication of rheumatic fever are a serious disease. Surgical treatment of valve diseases should be done before irreversible damage to the myocardium occurred. In this study, we aimed to present the early results of mechanical valve replacement operations. Method: A hundred patients with mechanical valve replacement surgery were retrospectively evaluated in Seyhan Application Center attached to our clinic between July 2007 and August 2011. Results: Fifty patients were male and 50 were women. The mean age of patients was 47.88 (18-78. Isolated aortic valve replacement (AVR was performed to 23 patients, isolated mitral valve replacement (MVR was 32, double valve replacement (AVR + MVR was 12, MVR + aortic valve valvuloplasty was 1, AVR + mitral kommissurotomi was 1, AVR + coronary artery bypass graft surgery (CABG was 17, MVR + CABG was 8, MVR + atrial septal defect closure was 2 and Bentall procedure.was 4 patients. In addition, ablation procedure was performed to 5 patients intraoperatively because of preoperative atrial fibrillation. Two patients (2 % died in early postoperative period. Conclusion: Mechanical prosthetic valves are used for surgical treatment of valve disease with low mortality and morbidity in a large group of patients like women that not to think to get pregnant, non advanced age group and patients have less risky for anticoagulation drug in our clinic. [Cukurova Med J 2012; 37(1.000: 49-54

  14. Transcatheter aortic valve implantation in failed bioprosthetic surgical valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John G; Bleiziffer, Sabine

    2014-01-01

    IMPORTANCE: Owing to a considerable shift toward bioprosthesis implantation rather than mechanical valves, it is expected that patients will increasingly present with degenerated bioprostheses in the next few years. Transcatheter aortic valve-in-valve implantation is a less invasive approach......, stroke, and New York Heart Association functional class. RESULTS: Modes of bioprosthesis failure were stenosis (n = 181 [39.4%]), regurgitation (n = 139 [30.3%]), and combined (n = 139 [30.3%]). The stenosis group had a higher percentage of small valves (37% vs 20.9% and 26.6% in the regurgitation...... and combined groups, respectively; P = .005). Within 1 month following valve-in-valve implantation, 35 (7.6%) patients died, 8 (1.7%) had major stroke, and 313 (92.6%) of surviving patients had good functional status (New York Heart Association class I/II). The overall 1-year Kaplan-Meier survival rate was 83...

  15. Performance Characteristics of an Isothermal Freeze Valve

    Energy Technology Data Exchange (ETDEWEB)

    Hailey, A.E.

    2001-08-22

    This document discusses performance characteristics of an isothermal freeze valve. A freeze valve has been specified for draining the DWPF melter at the end of its lifetime. Two freeze valve designs have been evaluated on the Small Cylindrical Melter-2 (SCM-2). In order to size the DWPF freeze valve, the basic principles governing freeze valve behavior need to be identified and understood.

  16. Tricuspid Valve Replacement, Mechnical vs. Biological Valve, Which Is Better?

    Directory of Open Access Journals (Sweden)

    Haitham Akram Altaani

    2013-06-01

    Full Text Available Background: The initial trial in tricuspid surgery is repair; however, replacement is done whenever the valve is badly diseased. Tricuspid valve replacement comprises 1.7% of all tricuspid valve surgeries. Materials and Methods: The present retrospective study was performed using the medical records of 21 cases who underwent tricuspid valve replacement from January 2002 until the end of December 2010. The mean age of the participants was 52.3±8.8 years and 66.7% were females. In addition, tricuspid valve replacement was associated with mitral valve surgery, aortic valve surgery, and both in 14.3%, 4.8%, and 33.3% of the cases, respectively. Yet, isolated tricuspid valve replacement and redo surgery were performed in 10 cases (47.6% and 8 cases (38.1%, respectively. Besides, trial of repair was done in 14 cases (66.7%. Moreover, biological and mechanical valves were used in 76.2% and 23.8% of the patients, respectively. Results: According to the results, early mortality was 23.8% and one year survival was 66.7%. Moreover, early mortality was caused by right ventricular failure, multiorgan failure, medistinitis, and intracerbral bleeding in 42%, 28.6%, 14.3%, and 14.3% of the cases, respectively. In addition, 57.1% of the deaths had occurred in the cases where the biological valve was used, while 42.9% of the deaths had taken place where the mechanical one was utilized. Conclusions: The patients who require tricuspid valve replacement are usually high risk surgical candidates with early and long term mortality. The findings of the current study showed no significant hemodynamic difference between mechanical and biological valves.

  17. Improved mitral valve coaptation and reduced mitral valve annular size after percutaneous mitral valve repair (PMVR) using the MitraClip system.

    Science.gov (United States)

    Patzelt, Johannes; Zhang, Yingying; Magunia, Harry; Ulrich, Miriam; Jorbenadze, Rezo; Droppa, Michal; Zhang, Wenzhong; Lausberg, Henning; Walker, Tobias; Rosenberger, Peter; Seizer, Peter; Gawaz, Meinrad; Langer, Harald F

    2017-08-01

    Improved mitral valve leaflet coaptation with consecutive reduction of mitral regurgitation (MR) is a central goal of percutaneous mitral valve repair (PMVR) with the MitraClip® system. As influences of PMVR on mitral valve geometry have been suggested before, we examined the effect of the procedure on mitral annular size in relation to procedural outcome. Geometry of the mitral valve annulus was evaluated in 183 patients undergoing PMVR using echocardiography before and after the procedure and at follow-up. Mitral valve annular anterior-posterior (ap) diameter decreased from 34.0 ± 4.3 to 31.3 ± 4.9 mm (P < 0.001), and medio-lateral (ml) diameter from 33.2 ± 4.8 to 32.4 ± 4.9 mm (P < 0.001). Accordingly, we observed an increase in MV leaflet coaptation after PMVR. The reduction of mitral valve ap diameter showed a significant inverse correlation with residual MR. Importantly, the reduction of mitral valve ap diameter persisted at follow-up (31.3 ± 4.9 mm post PMVR, 28.4 ± 5.3 mm at follow-up). This study demonstrates mechanical approximation of both mitral valve annulus edges with improved mitral valve annular coaptation by PMVR using the MitraClip® system, which correlates with residual MR in patients with MR.

  18. Thermo-electric valve

    Science.gov (United States)

    Chamberland, R. R.; Stanland, A. J.

    1985-02-01

    A thermo-electric valve is described for scuttling floating devices comprising, a cylindrical sleeve affixed to and passing through a bulkhead separating a pressurized medium on one side from a lower pressure space on the other side, a piston moveably mounted within the sleeve bore and exposed to the pressurized medium having a portion thereof blocking the sleeve bore, an O-ring sealing the gap between the piston head and the sleeve bore, a fully compressed spring pressing against the piston, a rigid dielectric washer and a low power resistor holding the piston against the spring. In operation a low current is passed through the resistor, disintegrating it and releasing the spring's stored energy. This actuates the valve by expelling the piston which allows the pressurized fluid or gas to enter the lower pressure space.

  19. Patents and heart valve surgery--I: mechanical valves.

    Science.gov (United States)

    Cheema, Faisal H; Hussain, Nasir; Kossar, Alexander P; Polvani, Gianluca

    2013-04-01

    Valvular heart disease, inherited or acquired, affects more than 5 million Americans yearly. Whereas medical treatment is beneficial in the initial stages of valvular heart disease, surgical correction provides symptomatic relief and long-term survival benefits. Surgical options include either repair or replacement using mechanical or bio-prosthetic valves. Patient age and the post-operative need for anticoagulation therapy are major determinants of the choice between use of mechanical or bio-prosthetic valves. Since the first mechanical valves were made available several decades ago, the incorporation of increasingly sophisticated materials and methodologies has led to substantial improvements in the valve design, and has catalyzed a parallel increase in the amount of patents issued for these emerging technologies. In this paper, we have chronologically reviewed such patents, briefly discussed various challenges that mechanical heart valve implementation is faced with and finally reviewed some of the strategies employed to overcome such obstacles. An ideal prosthetic heart valve would comprehensively mimic the natural hemodynamics and physiology of the native heart valve. Additionally, such a valve would be easily implantable, associated with a minimal risk of thrombosis and thus need for anti-coagulation, and with a proven long-term durability. With cutting edge technological advancements in the recent times, the ongoing innovative and collaborative efforts of physicians, scientists, and engineers will not seize until an ideal mechanical heart valve becomes a reality.

  20. Aortic valve replacement

    DEFF Research Database (Denmark)

    Kapetanakis, Emmanouil I; Athanasiou, Thanos; Mestres, Carlos A

    2008-01-01

    countries. METHODS: A multi-institutional, non-randomized, retrospective analysis was conducted among 2,932 patients who underwent AVR surgery at seven tertiary cardiac surgery centers throughout Europe. Demographic and perioperative variables including valve size and type, body surface area (BSA) and early...... and southern European countries. Imbalances in the prevalence of rheumatic heart disease, health resource availability and variations in surgical practice throughout Europe might be possible etiological causes....

  1. Anterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Vidyadhar P. Mali

    2006-07-01

    Full Text Available We studied the clinical presentation and management of four patients with anterior urethral valves; a rare cause of urethral obstruction in male children. One patient presented antenatally with oligohydramnios, bilateral hydronephrosis and bladder thickening suggestive of an infravesical obstruction. Two other patients presented postnatally at 1 and 2 years of age, respectively, with poor stream of urine since birth. The fourth patient presented at 9 years with frequency and dysuria. Diagnosis was established on either micturating cystourethrogram (MCU (in 2 or on cystoscopy (in 2. All patients had cystoscopic ablation of the valves. One patient developed a postablation stricture that was resected with an end-to-end urethroplasty. He had an associated bilateral vesicoureteric junction (VUJ obstruction for which a bilateral ureteric reimplantation was done at the same time. On long-term follow-up, all patients demonstrated a good stream of urine. The renal function is normal. Patients are continent and free of urinary infections. Anterior urethral valves are rare obstructive lesions in male children. The degree of obstruction is variable, and so they may present with mild micturition difficulty or severe obstruction with hydroureteronephrosis and renal impairment. Hence, it is important to evaluate the anterior urethra in any male child with suspected infravesical obstruction. The diagnosis is established by MCU or cystoscopy and the treatment is always surgical, either a transurethral ablation or an open resection. The long-term prognosis is good.

  2. Direct aortic access for transcatheter aortic valve replacement with a fully repositionable and retrievable nonmetallic valve system.

    Science.gov (United States)

    Bushnaq, Hasan; Metz, Dietrich; Petrov, Asen; Frantz, Stefan; Hofmann, Ulrich; Raspé, Christoph; Treede, Hendrik

    2016-12-01

    The standard procedure of transcatheter aortic valve implantation involves transfemoral access. Nevertheless, the use of this access route is limited by the vessel diameter, calcification, and tortuosity, making a subgroup of patients ineligible for peripheral access. We report the first use of direct aortic transcatheter aortic valve implantation with the Direct Flow Medical valve (Direct Flow Medical, Inc, Santa Rosa, Calif) in 15 patients at the Halle-Wittenberg University. Between January 2014 and May 2015, 55 patients with severe aortic valve disease underwent transcatheter aortic valve implantation with the Direct Flow Medical valve at the Halle-Wittenberg University. Subgroups of 15 patients were treated using direct aortic access because of small vessel diameter, excessive calcification, or extreme tortuosity of the iliofemoral vessels. The mean patient age was 79.1 ± 6.72 years, and 10 patients (66%) were male. The mean logistic European System for Cardiac Operative Risk Evaluation was 23.4% ± 16.9%, and the mean Society of Thoracic Surgeons score was 7.8% ± 6.8%. Access related to redo-sternotomy during transcatheter aortic valve implantation was required in 4 patients (27%). Valve retrieval was performed in 2 patients (13%). There was no conversion to surgical aortic valve replacement and no incidence of major stroke. The postimplant mean gradient was 9.3 ± 2.5 mm Hg. No patient had moderate or severe paravalvular leakage. All patients survived the first 30 days. Direct aortic access seems to be a feasible and safe endovascular alternative for implantation of the Direct Flow Medical valve. This access provides direct and accurate control of the entire implantation procedure. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  3. Optothermally actuated capillary burst valve

    Science.gov (United States)

    Eriksen, Johan; Bilenberg, Brian; Kristensen, Anders; Marie, Rodolphe

    2017-04-01

    We demonstrate the optothermal actuation of individual capillary burst valves in an all-polymer microfluidic device. The capillary burst valves are realised in a planar design by introducing a fluidic constriction in a microfluidic channel of constant depth. We show that a capillary burst valve can be burst by raising the temperature due to the temperature dependence of the fluid surface tension. We address individual valves by using a local heating platform based on a thin film of near infrared absorber dye embedded in the lid used to seal the microfluidic device [L. H. Thamdrup et al., Nano Lett. 10, 826-832 (2010)]. An individual valve is burst by focusing the laser in its vicinity. We demonstrate the capture of single polystyrene 7 μm beads in the constriction triggered by the bursting of the valve.

  4. Update of transcatheter valve treatment.

    Science.gov (United States)

    Liu, Xian-bao; Wang, Jian-an

    2013-08-01

    Transcatheter valve implantation or repair has been a very promising approach for the treatment of valvular heart diseases since transcatheter aortic valve implantation (TAVI) was successfully performed in 2002. Great achievements have been made in this field (especially TAVI and transcatheter mitral valve repair--MitraClip system) in recent years. Evidence from clinical trials or registry studies has proved that transcatheter valve treatment for valvular heart diseases is safe and effective in surgical high-risk or inoperable patients. As the evidence accumulates, transcatheter valve treatment might be an alterative surgery for younger patients with surgically low or intermediate risk valvular heart diseases in the near future. In this paper, the updates on transcatheter valve treatment are reviewed.

  5. Mitral valve repair versus replacement

    Science.gov (United States)

    Keshavamurthy, Suresh; Gillinov, A. Marc

    2015-01-01

    Degenerative, ischemic, rheumatic and infectious (endocarditis) processes are responsible for mitral valve disease in adults. Mitral valve repair has been widely regarded as the optimal surgical procedure to treat mitral valve dysfunction of all etiologies. The supporting evidence for repair over replacement is strongest in degenerative mitral regurgitation. The aim of the present review is to summarize the data in each category of mitral insufficiency and to provide recommendations based upon this data. PMID:26309824

  6. Latest design of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Kurzhofer, U.; Stolte, J.; Weyand, M.

    1996-12-01

    Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

  7. The ventilation-perfusion relation and gas exchange in mitral valve disease and coronary artery disease. Implications for anesthesia, extracorporeal circulation, and cardiac surgery.

    Science.gov (United States)

    Hachenberg, T; Tenling, A; Hansson, H E; Tydén, H; Hedenstierna, G

    1997-04-01

    Patients with mitral valve disease (MVD) are at greater risk for respiratory complications after cardiac surgery compared with patients with coronary artery disease (CAD). The authors hypothesized that ventilation-perfusion (VA/Q) inequality is more pronounced in patients with MVD before and after induction of anesthesia and during and after surgery when extracorporeal circulation (ECC) is used. In patients with MVD (n = 12) or with CAD (n = 12), VA/Q distribution was determined using the multiple inert gas elimination technique. Intrapulmonary shunt (Qs/Qr) defined as regions with VA/Q 100 [% of VE]) were calculated from the retention/excretion data of the inert gases. Recordings were obtained while patients spontaneously breathed air in the awake state, during mechanical ventilation after induction of anesthesia, after separation of patients from ECC, and 4 h after operation. Qs/Qr was low in the awake state (MVD group, 3% +/- 3%; CAD group, 3% +/- 4%) and increased after induction of anesthesia to 10% +/- 8% (MVD group, P < 0.05) and 11% +/- 7% (CAD group, P < 0.01). Qs/Qr increased further after separation from ECC (MVD group, 24% +/- 9%, P < 0.01; CAD group, 23% +/- 7%, P < 0.01). Similarly, alveolar-arterial oxygen tension difference (PA-aO2) increased from 168 +/- 54 mmHg (anesthetized state) to 427 +/- 138 mmHg after ECC (MVD group, P < 0.01) and from 153 +/- 65 mmHg to 377 +/- 101 mmHg (CAD group, P < 0.01). In both groups, PA-aO2 was correlated with Qs/Qr. Four hours after operation, Qs/Qr had decreased significantly to 8% +/- 6% (CAD group) and 10% +/- 6% (MVD group). PA-aO2 and Qs/Qr showed no significant differences between the CAD and MVD groups. Qs/Qr is the main pathophysiologic mechanism of gas exchange impairment during cardiac surgery for MVD or CAD. Impairment of pulmonary gas exchange secondary to general anesthesia, cardiac surgery, and ECC are comparable for patients undergoing myocardial revascularization or mitral valve surgery.

  8. Oil Stiction in Fast Switching Annular Seat Valves for Digital Displacement Fluid Power Machines

    DEFF Research Database (Denmark)

    Roemer, Daniel Beck; Johansen, Per; Pedersen, Henrik C.

    2014-01-01

    Digital Displacement (DD) fluid power machines utilizes electronically controlled seat valves connected to pressure chambers to obtain variable displacement with high operational efficiency and high bandwidth. To achieve high efficiency, fast valve switching is essential and all aspects related...... to the dynamic behaviour of the seat valves must be considered to optimize the machine efficiency. A significant effect influencing the valves switching performance is the presence of oil stiction when separating the contact surfaces in valve opening movement. This oil stiction force is limited by cavitation...... for low pressure levels, e.g. valves connected to the low pressure manifold, however for valves operated at higher pressure levels, the oil stiction force is dominating when the separating surfaces are close to contact. This paper presents an analytic solution to the oil stiction force for annular seat...

  9. Graphene spin valve: An angle sensor

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Zahir, E-mail: zahir.upc@gmail.com [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Hussain, Ghulam [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Siddique, Salma [Department of Bioscience & Biotechnology, Sejong University, Seoul 143-747 (Korea, Republic of); Iqbal, Muhammad Waqas [Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, Lahore (Pakistan)

    2017-06-15

    Graphene spin valves can be optimized for various spintronic applications by tuning the associated experimental parameters. In this work, we report the angle dependent magnetoresistance (MR) in graphene spin valve for different orientations of applied magnetic field (B). The switching points of spin valve signals show a clear shift towards higher B for each increasing angle of the applied field, thus sensing the response for respective orientation of the magnetic field. The angular variation of B shifts the switching points from ±95 G to ±925 G as the angle is varied from 0° to 90° at 300 K. The observed shifts in switching points become more pronounced (±165 G to ±1450 G) at 4.2 K for similar orientation. A monotonic increase in MR ratio is observed as the angle of magnetic field is varied in the vertical direction at 300 K and 4.2 K temperatures. This variation of B (from 0° to 90°) increases the magnitude of MR ratio from ∼0.08% to ∼0.14% at 300 K, while at 4.2 K it progresses to ∼0.39% from ∼0.14%. The sensitivity related to angular variation of such spin valve structure can be employed for angle sensing applications.

  10. Experimental substantiation of the design of a prosthetic heart valve for «valve-in-valve» implantation

    Directory of Open Access Journals (Sweden)

    K. Yu. Klyshnikov

    2017-01-01

    Full Text Available The aim of the study was to perform a series of in vitro tests of a prototype of the developing heart valve prosthesis to evaluate its functional characteristics. Materials and methods. In this work we have used the frames and full prototypes of the prosthesis, consisting of a stent-like stainless steel support frame with mounted biological leaflets and cover. The authors evaluated the calculated and experimental forces necessary for the displacement of the sutureless implanted prosthesis using the test machine under uniaxial tension. The risk of defects and damages to the supporting framework as a result of implantation was evaluated by scanning electron microscopy. The hydrodynamic characteristics of the prosthesis were investigated under physiological conditions and «valvein-valve» implantation. Evaluation of the ergonomics and applicability of the proposed construction on the cadaver heart model of cattle was carried out. Results. As a result of the forces assessment, it was found that the force required to shear the prosthesis was 3.12 ± 0.37 N, while the calculated value was 1.7 N, which is significantly lower than the obtained value. The comparison of the images obtained with small and large magnifications demonstrated the absence of critical surface defects. Additional analysis under the super-large magnifications also did not reveal problem areas. During the hydrodynamic study, it was shown that the average transplant gradient increased slightly from 2.8–3.4 to 3.2–4.5 mm Hg for the initial prosthesis and the «valve-in-valve» complex, respectively. The decrease of the effective orifice area was 6–9% relative to the initial one. Evaluation of the implantation technique demonstrated the consistency of the approach: the use of the developed holder in combination with the balloon implantation system made it possible to position the prosthesis throughout the procedure. Conclusion. The series of tests demonstrates the consistency

  11. Pressure locking and thermal binding of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, E.M.

    1996-12-01

    Pressure locking and thermal binding represent potential common mode failure mechanisms that can cause safety-related power-operated gate valves to fail in the closed position, thus rendering redundant safety-related systems incapable of performing their safety functions. Supplement 6 to Generic Letter 89-10, {open_quotes}Safety-Related Motor-Operated Gate Valve Testing and Surveillance,{close_quotes} provided an acceptable approach to addressing pressure locking and thermal binding of gate valves. More recently, the NRC has issued Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves,{close_quotes} to request that licensees take certain actions to ensure that safety-related power-operated gate valves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions within the current licensing bases. Over the past two years, several plants in Region I determined that valves in certain systems were potentially susceptible to pressure locking and thermal binding, and have taken various corrective actions. The NRC Region I Systems Engineering Branch has been actively involved in the inspection of licensee actions in response to the pressure locking and thermal binding issue. Region I continues to maintain an active involvement in this area, including participation with the Office of Nuclear Reactor Regulation in reviewing licensee responses to Generic Letter 95-07.

  12. Extracellular Matrix Biomarker, Fibulin-1, Is Closely Related to NT-proBNP and Soluble Urokinase Plasminogen Activator Receptor in Patients with Aortic Valve Stenosis (The SEAS Study)

    DEFF Research Database (Denmark)

    Kruger, Ruan; Rasmussen, Lars M; Argraves, William S

    2014-01-01

     = 0.16, p = 0.006, βyear4 = 0.13, p = 0.03) at the expense of the association to aortic valve area index (AVAI) (βyear0 = -0.14, p = 0.005, βyear1 = -0.08, p = 0.11, βyear4 = -0.06, p = 0.22) independently of age, gender, creatinine, and serum aspartate aminotransferase (Adj.Ryear02 = 0.19, Adj.......01), and suPAR (βyear0 = 0.09, p = 0.26, βyear1 = 0.23, βyear4 = 0.21, both pgender, AST and treatment allocation. CONCLUSIONS: Increased levels of fibulin-1 were independently associated with higher levels of suPAR and NT-proBNP especially in patients with lower AVAI, suggesting...

  13. Fluid and Structural Analysis of Large Butterfly Valve

    Science.gov (United States)

    Song, Xueguan; Wang, Lin; Park, Youngchul

    2008-10-01

    A butterfly valve of large diameter is commonly used as control equipments in applications where the inlet velocity is fast and the pressure is relatively high. Because of the size of the valve is too large, therefore it's too difficult to conduct the experiment in a laboratory. In this paper, the numerical simulation using commercial package-CFX and ANSYS was conducted. In order to do fluid analysis and structural analysis perfectly, large valve models are generated in three dimensions without much simplification, the result of fluid analysis is also fully coupled to the structural domain by the fluid-structural interface to provide an exacter initial condition. In addition to describe the flow patterns and to measure the performance coefficients when the valves with various open angles were used, the verification of the safety performance whether the valve could work normally at those conditions or not was conducted. Fortunately, the result shows this type valve is safe in a given inlet velocity of 3m/s, and it's not necessary to be strengthened anywhere, and if need be, the shape of valve disc can be optimized to reduce the weight of disc, and also to make the flow coefficient be closer to the suggested level.

  14. Novel characterization of lymphatic valve formation during corneal inflammation.

    Directory of Open Access Journals (Sweden)

    Tan Truong

    Full Text Available Lymphatic research has progressed rapidly in recent years. Though lymphatic dysfunction has been found in a wide array of disorders from transplant rejection to cancer metastasis, to date, there is still little effective treatment for lymphatic diseases. The cornea offers an optimal site for lymphatic research due to its accessible location, transparent nature, and lymphatic-free but inducible features. However, it still remains unknown whether lymphatic valves exist in newly formed lymphatic vessels in the cornea, and how this relates to an inflammatory response. In this study, we provide the first evidence showing that lymphatic valves were formed in mouse cornea during suture-induced inflammation with the up-regulation of integrin alpha 9. The number of corneal valves increased with the progression of inflammatory lymphangiogenesis. Moreover, we have detected lymphatic valves at various developmental stages, from incomplete to more developed ones. In addition to defining the average diameter of lymphatic vessels equipped with lymphatic valves, we also report that lymphatic valves were more often located near the branching points. Taken together, these novel findings not only provide new insights into corneal lymphatic formation and maturation, but also identify a new model for future investigation on lymphatic valve formation and possibly therapeutic intervention.

  15. Prosthetic valve endocarditis after transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

    Olsen, Niels Thue; De Backer, Ole; Thyregod, Hans G H

    2015-01-01

    BACKGROUND: Transcatheter aortic valve implantation (TAVI) is an advancing mode of treatment for inoperable or high-risk patients with aortic stenosis. Prosthetic valve endocarditis (PVE) after TAVI is a serious complication, but only limited data exist on its incidence, outcome, and procedural...

  16. In vitro evaluation of implantation depth in valve-in-valve using different transcatheter heart valves.

    Science.gov (United States)

    Simonato, Matheus; Azadani, Ali N; Webb, John; Leipsic, Jonathon; Kornowski, Ran; Vahanian, Alec; Wood, David; Piazza, Nicolo; Kodali, Susheel; Ye, Jian; Whisenant, Brian; Gaia, Diego; Aziz, Mina; Pasala, Tilak; Mehilli, Julinda; Wijeysundera, Harindra C; Tchetche, Didier; Moat, Neil; Teles, Rui; Petronio, Anna Sonia; Hildick-Smith, David; Landes, Uri; Windecker, Stephan; Arbel, Yaron; Mendiz, Oscar; Makkar, Raj; Tseng, Elaine; Dvir, Danny

    2016-09-18

    Transcatheter heart valve (THV) implantation in failed bioprosthetic valves (valve-in-valve [ViV]) offers an alternative therapy for high-risk patients. Elevated post-procedural gradients are a significant limitation of aortic ViV. Our objective was to assess the relationship between depth of implantation and haemodynamics. Commercially available THVs used for ViV were included in the analysis (CoreValve Evolut, SAPIEN XT and the Portico valve). THVs were implanted in small surgical valves (label size 19 mm) to simulate boundary conditions. Custom-mounted pulse duplicators registered relevant haemodynamic parameters. Twenty-eight experiments were performed (13 CVE, 5 SXT and 10 Portico). Ranges of depth of implantation were: CVE: -1.2 mm to 15.7 mm; SXT: -2.2 mm to 7.5 mm; Portico: 1.4 mm to 12.1 mm. Polynomial regression established a relationship between depth of implantation and valvular mean gradients (CVE: p<0.001; SXT: p=0.01; Portico: p=0.002), as well as with EOA (CVE: p<0.001; SXT: p=0.02; Portico valve: p=0.003). In addition, leaflet coaptation was better in the high implantation experiments for all valves. The current comprehensive bench testing assessment demonstrates the importance of high device position for the attainment of optimal haemodynamics during aortic ViV procedures.

  17. High Reliability Cryogenic Piezoelectric Valve Actuator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cryogenic fluid valves are subject to harsh exposure and actuators to drive these valves require robust performance and high reliability. DSM's piezoelectric...

  18. Multidetector CT imaging of mechanical prosthetic heart valves: quantification of artifacts with a pulsatile in-vitro model

    NARCIS (Netherlands)

    Symersky, Petr; Budde, Ricardo P. J.; Westers, Paul; de Mol, Bas A. J. M.; Prokop, Mathias

    2011-01-01

    Multidetector computed tomography (MDCT) can detect the cause of prosthetic heart valve (PHV) dysfunction but is hampered by valve-induced artifacts. We quantified artifacts of four PHV using a pulsatile in-vitro model and assessed the relation to leaflet motion and valve design. A Medtronic Hall

  19. Multidetector CT imaging of mechanical prosthetic heart valves : quantification of artifacts with a pulsatile in-vitro model

    NARCIS (Netherlands)

    Symersky, Petr; Budde, Ricardo P. J.; Westers, Paul; de Mol, Bas A. J. M.; Prokop, Mathias

    2011-01-01

    Objectives Multidetector computed tomography (MDCT) can detect the cause of prosthetic heart valve (PHV) dysfunction but is hampered by valve-induced artifacts. We quantified artifacts of four PHV using a pulsatile in-vitro model and assessed the relation to leaflet motion and valve design. Methods

  20. 70. Surgical mitral valve replacement with modified Melody valve in children

    Directory of Open Access Journals (Sweden)

    Ahmed Badr Elwy

    2015-10-01

    Conclusions: The modified Melody valve is a viable option for children MV annular diameters, providing a valid alternative to existing prostheses. The technique is relatively easy and the short term result is very good. This prosthesis will be particularly attractive if maintaining competence after subsequent dilations as the child grows.

  1. Experimental study on the Reynolds and viscous shear stress of bileaflet mechanical heart valves in a pneumatic ventricular assist device.

    Science.gov (United States)

    Lee, Hwansung; Tatsumi, Eisuke; Taenaka, Yoshiyuki

    2009-01-01

    Our group is currently developing a pneumatic ventricular assist device (PVAD). In general, the major causes of hemolysis in a pulsatile VAD are cavitation, and Reynolds shear stress (RSS) in the mechanical heart valve (MHV). In a previous study, we investigated MHV cavitation. To select the optimal bileaflet valve for our PVAD, in the current study, we investigated RSS and viscous shear stress (VSS) downstream of three different types of commercial bileaflet valves by means of 2D particle image velocimetry (PIV). To carry out flow visualization inside the blood pump and near the valve, we designed a model pump with the same configuration as that of our PVAD. Three types of bileaflet valves (i.e., the ATS valve, the St. Jude valve, and the Sorin Bicarbon valve) were mounted at the aortic position of the model pump, and flow was visualized according to the PIV method. The maximum flow velocity and RSS of the Sorin Bicarbon valve were lower than those of the other two bileaflet valves. The maximum VSS was only 1% of the maximum RSS. Thus, the effect of VSS on blood cell trauma was neglected. The Sorin Bicarbon valve exhibited relatively low levels of RSS, and was therefore considered to be the best valve for our PVAD among the three valves tested.

  2. Minimally invasive aortic valve replacement

    DEFF Research Database (Denmark)

    Foghsgaard, Signe; Schmidt, Thomas Andersen; Kjaergard, Henrik K

    2009-01-01

    In this descriptive prospective study, we evaluate the outcomes of surgery in 98 patients who were scheduled to undergo minimally invasive aortic valve replacement. These patients were compared with a group of 50 patients who underwent scheduled aortic valve replacement through a full sternotomy...

  3. Butterfly valve apparatus and method

    Energy Technology Data Exchange (ETDEWEB)

    Ball, L.K.; Hines, M.U.; Miller, T.L.

    1990-10-23

    This patent describes a method of controlling fluid flow in a duct, and duct having a wall bounding a flow path wherein flows the fluid. It comprises: disposing a plate-like valve member in the flow path, which valve member is pivotally movable about an axis generally transverse to the duct between a first position transverse to and closing the flow path and a second position generally parallel with the flow path to open and allow fluid flow therein: transecting the valve member with the pivot axis to define with respect to direction of the fluid flow in the duct and pivotal movement of the valve member toward the open position an upstream valve member wing and a downstream valve member wing each substantially equal in area: increasing the effective area of the valve member upon which the fluid flow exerts fluid dynamic flow forces; and pivoting the valve member toward the second open position thereof in response to the increase of effective area.

  4. The spin-valve transistor

    NARCIS (Netherlands)

    Anil Kumar, P.S.; Lodder, J.C.

    2000-01-01

    The spin-valve transistor is a magnetoelectronic device that can be used as a magnetic field sensor. It has a ferromagnet-semiconductor hybrid structure. Using a vacuum metal bonding technique, the spin-valve transistor structure Si/Pt/NiFe/Au/Co/Au/Si is obtained. It employs hot electron transport

  5. Mechanical Valve Replacement: Early Results

    Directory of Open Access Journals (Sweden)

    Habib Cakir

    2012-03-01

    Conclusion: Mechanical prosthetic valves are used for surgical treatment of valve disease with low mortality and morbidity in a large group of patients like women that not to think to get pregnant, non advanced age group and patients have less risky for anticoagulation drug in our clinic. [Cukurova Med J 2012; 37(1: 49-54

  6. Predictors of Health-Related Quality of Life Decline after Transcatheter Aortic Valve Replacement in Older Patients with Severe Aortic Stenosis.

    Science.gov (United States)

    Boureau, A S; Trochu, J N; Rouaud, A; Hureau, R; Jaafar, P; Manigold, T; Letocart, V; Guerin, P; Berrut, G; de Decker, L

    2017-01-01

    Transcatheter aortic-valve implantation (TAVI) has been shown to improve survival and quality of life in patients with severe aortic stenosis. However, one-third of patients have poor outcome as death, functional decline or quality of life (QoL) decline. The aim of this study was to determine cardiac and geriatric predictors of physical and mental QoL decline 6 months after a TAVI procedure in patients aged 75 and older. Between January 2013 and June 2014, we did a prospective and multicenter study including patients ≥ 75 years old referred for TAVI. The primary outcome was the measure of QoL, assessed by the Short Form 36 survey (SF-36), before and 6 months after the intervention. Association between QoL decline and baseline characteristics including cardiac and geriatric factors was analysed by logistic regression models. Mean age of the 150 patients studied was 83.7 years old and 56% were men. The primary end point, mean SF-36 physical summary score, significantly improved between baseline and 6-month (33.6 vs. 36.4, p=0.003) whereas mental component score significantly decreased (48.2 vs. 36.4, p-valuepatients with presence of depressive symptoms before the intervention had mental QoL improvement at six months (OR 0.04 [0.01-0.19], p-valuegeriatric predictors were associated with physical QoL decline. The mental QoL significantly decreased and patients with preoperative depressive symptoms had mental QoL improvement at six months. Researches are needed to confirm that mental QoL of patients with depressive symptoms can be improved by TAVI.

  7. Ahmed glaucoma valve implant: surgical technique and complications

    Directory of Open Access Journals (Sweden)

    Riva I

    2017-02-01

    Full Text Available Ivano Riva,1 Gloria Roberti,1 Francesco Oddone,1 Anastasios GP Konstas,2 Luciano Quaranta3 1IRCCS “Fondazione GB Bietti per l’Oftalmologia”, Rome, Italy; 21st University Department of Ophthalmology, Glaucoma Unit, AHEPA Hospital, Thessaloniki, Greece; 3Department of Medical and Surgical Specialties, Section of Ophthalmology, University of Brescia, Brescia, Italy Abstract: Implantation of Ahmed glaucoma valve is an effective surgical technique to reduce intraocular pressure in patients affected with glaucoma. While in the past, the use of this device was reserved to glaucoma refractory to multiple filtration surgical procedures, up-to-date mounting experience has encouraged its use also as a primary surgery for selected cases. Implantation of Ahmed glaucoma valve can be challenging for the surgeon, especially in patients who already underwent previous multiple surgeries. Several tips have to be acquired by the surgeon, and a long learning curve is always needed. Although the valve mechanism embedded in the Ahmed glaucoma valve decreases the risk of postoperative hypotony-related complications, it does not avoid the need of a careful follow-up. Complications related to this type of surgery include early and late postoperative hypotony, excessive capsule fibrosis around the plate, erosion of the tube or plate edge, and very rarely infection. The aim of this review is to describe surgical technique for Ahmed glaucoma valve implantation and to report related complications. Keywords: glaucoma, surgical technique, glaucoma drainage devices, Ahmed glaucoma valve, complications

  8. Transcatheter mitral valve implantation for inoperable severely calcified native mitral valve disease: A systematic review.

    Science.gov (United States)

    Puri, Rishi; Abdul-Jawad Altisent, Omar; del Trigo, Maria; Campelo-Parada, Francesco; Regueiro, Ander; Barbosa Ribeiro, Henrique; DeLarochellière, Robert; Paradis, Jean-Michel; Dumont, Eric; Rodés-Cabau, Josep

    2016-02-15

    Transcatheter mitral valve implantation (TMVI) for severely calcified native mitral valve disease recently emerged as a treatment option in patients deemed inoperable by conventional techniques. Yet no systematic appraisal currently exists characterizing this novel treatment paradigm. A systematic literature review summarizing the clinical, anatomical, peri- and post-procedural characteristics underscoring the technical feasibility of this procedure was performed. Nine publications describing 11 patients [mean age 68 ± 10 years, 82% female, 82% severe mitral stenosis (MS), 18% severe mitral regurgitation (MR)] were identified. Mean STS score, trans-mitral gradient and effective orifice area were 10.5 ± 4.6%, 12 ± 2.4 mm Hg and 0.93 ± 0.06 cm(2) respectively. All patients had severe, circumferential mitral annular calcification on imaging. Dedicated balloon-expanding transcatheter aortic valves were used in 10/11 cases, with 8/11 cases involving a true percutaneous approach with peri-procedural 3D trans-esophageal echocardiographic guidance; 3/11 cases involved an open left atrial approach. Following initial balloon inflation and valve deployment, procedural success rate was 73%, without residual paravalvular leaks (PVL). Successful immediate re-deployment of a 2nd valve was needed in 2 instances following significant PVL detection. Residual trans-valvular gradients ranged from 3 to 7 mm Hg, with no patient demonstrating >grade 2 MR. All patients survived the procedure, with 2 reported deaths on days 10- and 41 post-TMVI being non-cardiac-related. Mid-term clinical follow-up, reported in 8 patients, revealed 6 patients to be alive at 3-months with much improved functional status. TMVI for native severely calcified mitral valve disease appears technically feasible with acceptable initial acute and mid-term hemodynamic and clinical outcomes. The outcomes of an ongoing, dedicated global Sapien TMVI registry will shed further light on this evolving treatment

  9. Quantification and comparison of the mechanical properties of four human cardiac valves.

    Science.gov (United States)

    Pham, Thuy; Sulejmani, Fatiesa; Shin, Erica; Wang, Di; Sun, Wei

    2017-05-01

    mechanics have been conducted mainly on mitral and aortic valves or an individual valve, but none quantify and compare the mechanical and structural properties among the four valves from the same relatively healthy elderly patient population. In this study, the mechanical and microstructural properties of 114 leaflets of aortic, mitral, pulmonary and tricuspid valves from 12 human cadaver hearts were mechanically tested, analyzed and compared. Our results not only provided a baseline quantification of the mechanical properties of aged human valves, but a age range between patients (51-87years) also offers a better understanding of the age-dependent differences among the four valves. It is hoped that the obtained experimental data and associated constitutive parameters can facilitate studies of valve diseases, treatments and the development of interventional devices. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. Cracking a tricuspid perimount bioprosthesis to optimize a second transcatheter sapien valve-in-valve placement.

    Science.gov (United States)

    Brown, Stephen C; Cools, Bjorn; Gewillig, Marc

    2016-09-01

    Bioprosthetic valves degenerate over time. Transcatheter valve-in-valve procedures have become an attractive alternative to surgery. However, every valve increasingly diminishes the diameter of the valvar orifice. We report a 12-year-old female who had a previous transcatheter tricuspid valve-in-valve procedure; cracking the ring of a Carpentier Edwards Perimount valve by means of an ultrahigh pressure balloon allowed implantation of a further larger percutaneous valve. The advantage of this novel approach permits enlarging the inner valve diameter and may facilitate future interventions and prolong time to surgery. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  11. System for remotely servicing a top loading captive ball valve

    Science.gov (United States)

    Berry, S.M.; Porter, M.L.

    1996-06-25

    An attachment for facilitating servicing of a valve is disclosed including: an assembly composed of a valve seat defining a flow path, a flow control member movable relative to the valve seat for blocking or unblocking the valve seat, and a control device including a stem coupled to the flow control member and operable for moving the flow control member relative to the valve seat; a housing for receiving the assembly, the housing having an opening via which the assembly can be removed from, and installed in, the housing, and the housing having a plurality of threaded studs which surround the opening and project away from the housing; a valve housing cover for closing and sealing the opening in the housing, the cover having a first bore for passage of the stem of the control device when the assembly is installed in the housing and a plurality of second bores each located for passage of a respective stud when the cover closes the opening in the housing. A plurality of threaded nuts are engageable with the studs for securing the cover to the housing when the cover closes the opening in the housing, wherein the attachment comprises: a plurality of nut guide devices removable from the housing and each operatively associated with a respective stud for retaining a respective nut and guiding the respective nut into alignment with the respective stud to enable the respective nut to be rotated into engagement with the respective stud; and aligning the nut guide devices with the studs. 7 figs.

  12. Decellularized mitral valve in a long-term sheep model.

    Science.gov (United States)

    Iablonskii, Pavel; Cebotari, Serghei; Ciubotaru, Anatol; Sarikouch, Samir; Hoeffler, Klaus; Hilfiker, Andres; Haverich, Axel; Tudorache, Igor

    2018-01-29

    The objective of this study was to evaluate surgical handling, in vivo hemodynamic performance and morphological characteristics of decellularized mitral valves (DMVs) in a long-term sheep model. Ovine mitral valves were decellularized using detergents and β-mercaptoethanol. Orthotopic implantations were performed in 6-month-old sheep (41.3 ± 1.2 kg, n = 11) without annulus reinforcement. Commercially available stented porcine aortic valves [biological mitral valve (BMV), n = 3] were implanted conventionally and used as controls. Valve function was evaluated by transoesophageal echocardiography and explants were investigated by a routine bright field microscopy and immunofluorescent histology. During implantation, 2 DMVs required cleft closure of the anterior leaflet. All valves were competent on water test and early postoperative transoesophageal echocardiography. Six animals (DMV, n = 4; BMV, n = 2) survived 12 months. Six animals died within the first 4 months due to valve-related complications. At 12 months, transoesophageal echocardiography revealed severe degeneration in all BMVs. Macroscopically, BMV revealed calcification at the commissures and leaflet insertion area. Histological examination showed sporadic cells negative for endothelial nitric oxide synthase, von Willebrand factor and CD45 on their surface. In contrast, DMV showed no calcification or stenosis, and the regurgitation was trivial to moderate in all animals. Fibrotic hardening occurred only along the suture line of the valve annulus, immunostaining revealed collagen IV covering the entire leaflet surface and a repopulation with endothelial cells. Surgical implantation of DMV is feasible and results in good early graft function. Additional in vivo investigations are required to minimize the procedure-related complications and to increase the reproducibility of surgical implantation. Degenerative profile of allogeneic DMV is superior to commercially available

  13. The Diagnosis of Internal Leakage of Control Valve Based on the Grey Correlation Analysis Method

    Directory of Open Access Journals (Sweden)

    Zheng DING

    2014-07-01

    Full Text Available The valve plays an important part in the industrial automation system. Whether it operates normally or not relates with the quality of the products directly while its faults are relatively common because of bad working conditions. And the internal leakage is one of the common faults. Consequently, this paper sets up the experimental platform to make the valve in different working condition and collect relevant data online. Then, diagnose the internal leakage of the valve by using the grey correlation analysis method. The results show that this method can not only diagnose the internal leakage of valve accurately, but also distinguish fault degree quantitatively.

  14. Developments in mechanical heart valve prosthesis

    Indian Academy of Sciences (India)

    Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the ...

  15. Atrioventricular valve abnormalities in infancy: two-dimensional echocardiographic and angiocardiographic comparison.

    Science.gov (United States)

    Gutgesell, H P; Cheatham, J; Latson, L A; Nihill, M R; Mullins, C E

    1983-09-01

    The results of two-dimensional echocardiography and biplane angiocardiography from 47 infants with congenital atrioventricular (AV) valve abnormalities were compared. Eleven patients had atresia of the right AV valve, 10 had atresia of the left AV valve, 4 had hypoplasia of the right AV valve and 5 had hypoplasia of the left AV valve. Twelve patients had endocardial cushion defect, three had single ventricle and two had straddling of the left AV valve. There was agreement between the two techniques as to the number of AV valves present in each patient. The echocardiographic estimate of valve anular diameter was below normal in seven of the eight patients thought to have a hypoplastic anulus by angiocardiography. In 10 of the 12 patients with endocardial cushion defect, there was agreement between the two techniques as to the presence or absence of atrial and ventricular septal defect. The chordal attachments of straddling valves were better visualized by echocardiography; flow patterns and effective orifice size were better demonstrated by angiocardiography. The subcostal four chamber echocardiographic views and cranially angulated oblique angiocardiographic views were comparable and provided the best images for determination of the size and number of AV valves and their relation to the atrial and ventricular septa.

  16. Analysis of regurgitation, mean systolic pressure drop and energy losses for two artificial aortic valves.

    Science.gov (United States)

    Sakhaeimanesh, A A; Morsi, Y S

    1999-01-01

    The work reported here is related to the hydrodynamic performance of a Jellyfish valve and St Vincent valve in terms of total energy losses, mean systolic pressure drop and regurgitation. The in vitro experimental investigation was conducted at cardiac outputs of 3.5, 4.5 and 6.51 min-1 across the two valves and under pulsatile flow condition. It was found that the closure volume of the St Vincent valve was about 2.5 times higher than that of the Jellyfish valve. The total back flow losses on the other hand were found to be in the range of 36.5 to 107.1 and 85.5 to 192.5 mJ for the Jellyfish valve and St Vincent valve respectively. Moreover, the mean systolic pressure drop of the St Vincent valve was found to be higher than that of the Jellyfish valve. However, for all the operating conditions tested here, the Jellyfish valve showed superior hydrodynamic performance in terms of backflow and mean systolic pressure as well as energy losses.

  17. Injectable tissue engineered pulmonary heart valve implantation into the pig model: A feasibility study.

    Science.gov (United States)

    Schlegel, Franziska; Salameh, Aida; Oelmann, Katja; Halling, Michelle; Dhein, Stefan; Mohr, Friedrich W; Dohmen, Pascal M

    2015-06-24

    Transcatheter pulmonary valve replacement is currently performed in clinical trials, however limited by the use of glutaraldehyde treated bioprostheses. This feasibility study was performed to evaluate delivery-related tissue distortion during implantation of a tissue engineered (TE) heart valves. The injectable TE heart valve was mounted on a self-expanding nitinol stent (n=7) and delivered into the pulmonary position of seven pigs, (weight 26 to 31 kg), performing a sternotomy or limited lateral thoracotomy. Prior to implantation, the injectable TE heart valve was crimped and inserted into an applicator. Positioning of the implants was guided by fluoroscopy and after carefully deployment angiographic examination was performed to evaluate the correct delivered position. Hemodynamic measurements were performed by epicardial echocardiography. Finally, the animals were sacrificed and the injectable TE heart valves were inspected by gross examination and histological examination. Orthotopic delivery of the injectable TE heart valves were all successful performed, expect in one were the valve migrated due to a discrepancy of pulmonary and injectable TE valve size. Angiographic evaluation (n=6) showed normal valve function, supported by epicardial echocardiography in which no increase flow velocity was measured, neither trans- nor paravalvular regurgitation. Histological evaluation demonstrated absence of tissue damage due to the delivery process. Transcatheter implantation of an injectable TE heart valve seems to be possible without tissue distortion due to the delivery system.

  18. Transcatheter, valve-in-valve transapical aortic and mitral valve implantation, in a high risk patient with aortic and mitral prosthetic valve stenoses

    Directory of Open Access Journals (Sweden)

    Harish Ramakrishna

    2015-01-01

    Full Text Available Transcatheter valve implantation continues to grow worldwide and has been used principally for the nonsurgical management of native aortic valvular disease-as a potentially less invasive method of valve replacement in high-risk and inoperable patients with severe aortic valve stenosis. Given the burden of valvular heart disease in the general population and the increasing numbers of patients who have had previous valve operations, we are now seeing a growing number of high-risk patients presenting with prosthetic valve stenosis, who are not potential surgical candidates. For this high-risk subset transcatheter valve delivery may be the only option. Here, we present an inoperable patient with severe, prosthetic valve aortic and mitral stenosis who was successfully treated with a trans catheter based approach, with a valve-in-valve implantation procedure of both aortic and mitral valves.

  19. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, J. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States); Ansanelli, E. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States)

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market. In this project, the ARIES team sought to better understand the current usage of TRVs by key market players in steam and hot water heating and to conduct limited experiments on the effectiveness of new and old TRVs as a means of controlling space temperatures and reducing heating fuel consumption. The project included a survey of industry professionals, a field experiment comparing old and new TRVs, and cost-benefit modeling analysis using BEopt™ (Building Energy Optimization software).

  20. Serotonin Mechanisms in Heart Valve Disease I

    Science.gov (United States)

    Jian, Bo; Xu, Jie; Connolly, Jeanne; Savani, Rashmin C.; Narula, Navneet; Liang, Bruce; Levy, Robert J.

    2002-01-01

    Clinical disorders associated with increased serotonin [5-hydroxytryptamine (5-HT)] levels, such as carcinoid syndrome, and the use of serotonin agonists, such as fenfluoramine have been associated with a valvulopathy characterized by hyperplastic valvular and endocardial lesions with increased extracellular matrix. Furthermore, 5-HT has been demonstrated to up-regulate transforming growth factor (TGF)-β in mesangial cells via G-protein signal transduction. We investigated the hypothesis that increased exposure of heart valve interstitial cells to 5-HT may result in increased TGF-β1 expression and activity because of serotonin receptor-mediated signal transduction with activation of Gαq, and subsequently up-regulation of phospholipase C. Thus, in the present study we performed a clinical-pathological investigation of retrieved carcinoid and normal valve cusps using immunohistochemical techniques to detect the presence of TGF-β1 and other proteins associated with TGF-β expression, including TGF-β receptors I and II, latent TGF-β-associated peptide (LAP), and α-smooth muscle actin. Carcinoid valve cusps demonstrated the unusual finding of widespread smooth muscle actin involving the interstitial cells in the periphery of carcinoid nodules; these same cells were also positive for LAP. Normal valve cusps were only focally positive for smooth muscle actin and LAP. In sheep aortic valve interstitial cell cultures 5-HT induced TGF-β1 mRNA production and increased TGF-β1 activity. 5-HT also increased collagen biosynthesis at the dosages studied. Furthermore, TGF-β1 added to SAVIC cultures increased the production of sulfated glycan and hyaluronic acid. In addition, overexpression of Gαq using an adenoviral expression vector for a constitutively active Gαq mutant (Q209L-Gαq) resulted in increased phospholipase C activity as well as up-regulation of TGF-β expression and activity. These results strongly support the view that G-protein-related signal

  1. Management of a locked Strata valve.

    Science.gov (United States)

    Bullivant, Kelly J; Mitha, Alim P; Hamilton, Mark G

    2009-04-01

    The PS Medical Strata valve is a programmable shunt valve used in the treatment of hydrocephalus that allows for noninvasive changes in the pressure setting using a magnet. The Strata valve is sensitive to magnetic fields, and reprogramming is frequently necessary after MR imaging. A known but rare complication of the Strata valve is that the rotor can become locked, causing shunt malfunction. This complication can only occur in a first generation Strata valve.

  2. 3D Printed Multimaterial Microfluidic Valve

    OpenAIRE

    Keating, Steven J.; Gariboldi, Maria Isabella; Patrick, William G.; Sharma, Sunanda; Kong, David S.; Oxman, Neri

    2016-01-01

    We present a novel 3D printed multimaterial microfluidic proportional valve. The microfluidic valve is a fundamental primitive that enables the development of programmable, automated devices for controlling fluids in a precise manner. We discuss valve characterization results, as well as exploratory design variations in channel width, membrane thickness, and membrane stiffness. Compared to previous single material 3D printed valves that are stiff, these printed valves constrain fluidic deform...

  3. Human antibody recognition of xenogeneic antigens (NeuGc and Gal) on porcine heart valves: could genetically modified pig heart valves reduce structural valve deterioration?

    Science.gov (United States)

    Lee, Whayoung; Long, Cassandra; Ramsoondar, Jagdeece; Ayares, David; Cooper, David K C; Manji, Rizwan A; Hara, Hidetaka

    2016-09-01

    Glutaraldehyde-fixed bioprosthetic heart valves (GBHVs) derived from wild-type (WT, genetically unmodified) pigs are widely used clinically for heart valve replacement. There is evidence that their failure is related to an immune response. The use of valves from genetically engineered pigs that do not express specific pig antigens may prolong GBHV survival. Our aims were to determine (i) expression of Gal and NeuGc on heart (aortic and pulmonary) valves and pericardium of WT, α1,3-galactosyltransferase gene knockout (GTKO) and GTKO/N-glycolylneuraminic acid gene-knockout (GTKO/NeuGcKO) pigs in comparison with three different commercially available GBHVs and (ii) to determine human antibody binding to these tissues. Wild-type, GTKO/CD46, and GTKO/CD46/NeuGcKO pig valves and pericardium were tested (i) fresh and (ii) after fixation with glutaraldehyde (0.02%, 0.2%, 2%). Sections of GBHVs, fresh and fixed valves, and pericardium were stained for Gal and NeuGc expression, and for human IgM and IgG antibody binding. Gal and NeuGc expression was high on all GBHVs and WT pig valves/pericardium, but was absent after antigen-specific-knockout. There was no difference in antigen expression or antibody binding among WT aortic, pulmonary valves, and pericardium as well as GBHVs. Glutaraldehyde fixation did not alter expression of Gal or NeuGc. After incubation with human serum, human IgM and IgG bound to all GBHVs and WT pig valves/pericardium. Valves from GTKO/CD46 pigs and, particularly, GTKO/CD46/NeuGcKO pigs (with/without glutaraldehyde fixation) showed less IgM and IgG binding. Compared to WT pigs, GTKO/CD46/NeuGcKO pigs would be preferable sources of GBHVs, because the absence of Gal/NeuGc expression reduces human antibody binding. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Treatment of Aortic, Mitral and Tricuspid Structural Bioprosthetic Valve Deterioration Using the Valve-in-Valve Technique.

    Science.gov (United States)

    Codner, Pablo; Assali, Abid; Vaknin-Assa, Hana; Shapira, Yaron; Orvin, Katia; Sharony, Ram; Sagie, Alexander; Kornowski, Ran

    2015-05-01

    The percutaneous approach for a failed bioprosthetic valve is an emerging alternative to redo-valve surgery in patients at high surgical risk. The study aim was to describe the treatment of patients with structural bioprosthetic valve deterioration, using the valve-in-valve technique. A total of 33 consecutive patients with symptomatic structural bioprosthetic valve deterioration was treated at the authors' institution, using the valve-in-valve technique. The valve-in-valve procedure in the aortic position was performed in 23 patients (mean age 81.4 ± 5.9 years; mean STS score 9.6 ± 5.4). The self-expandable and balloon-expandable devices were used in 21 cases (91.3%) and two cases (8.7%), respectively. Procedures were performed via the trans-femoral, trans-axillary and trans-apical routes in 18 (78.2%), three (13%) and two (8.7%) cases, respectively. After the procedure, all patients were in NYHA class I/II. Survival rates were 95.6% at the one-year follow up. The valve-in-valve procedure in the mitral position was performed in 10 patients (mean age 73.6 ± 15 years; mean STS score 7.7 ± 4.1). All procedures were performed using the balloon-expandable device via the trans-apical route. The composite end point of device success was achieved in all patients. Survival rates were 100% and 75% at one month and two years' follow up, respectively. A single valve-in-valve implantation within a failed tricuspid bioprosthetic valve was also successfully performed. In the authors' experience, the valve-in-valve technique for the treatment of a wide range of bioprosthetic valve deterioration modes of failure in different valve positions is safe and very effective.

  5. Fibrotic Aortic Valve Stenosis in Hypercholesterolemic/Hypertensive Mice.

    Science.gov (United States)

    Chu, Yi; Lund, Donald D; Doshi, Hardik; Keen, Henry L; Knudtson, Kevin L; Funk, Nathan D; Shao, Jian Q; Cheng, Justine; Hajj, Georges P; Zimmerman, Kathy A; Davis, Melissa K; Brooks, Robert M; Chapleau, Mark W; Sigmund, Curt D; Weiss, Robert M; Heistad, Donald D

    2016-03-01

    Hypercholesterolemia and hypertension are associated with aortic valve stenosis (AVS) in humans. We have examined aortic valve function, structure, and gene expression in hypercholesterolemic/hypertensive mice. Control, hypertensive, hypercholesterolemic (Apoe(-/-)), and hypercholesterolemic/hypertensive mice were studied. Severe aortic stenosis (echocardiography) occurred only in hypercholesterolemic/hypertensive mice. There was minimal calcification of the aortic valve. Several structural changes were identified at the base of the valve. The intercusp raphe (or seam between leaflets) was longer in hypercholesterolemic/hypertensive mice than in other mice, and collagen fibers at the base of the leaflets were reoriented to form a mesh. In hypercholesterolemic/hypertensive mice, the cusps were asymmetrical, which may contribute to changes that produce AVS. RNA sequencing was used to identify molecular targets during the developmental phase of stenosis. Genes related to the structure of the valve were identified, which differentially expressed before fibrotic AVS developed. Both RNA and protein of a profibrotic molecule, plasminogen activator inhibitor 1, were increased greatly in hypercholesterolemic/hypertensive mice. Hypercholesterolemic/hypertensive mice are the first model of fibrotic AVS. Hypercholesterolemic/hypertensive mice develop severe AVS in the absence of significant calcification, a feature that resembles AVS in children and some adults. Structural changes at the base of the valve leaflets include lengthening of the raphe, remodeling of collagen, and asymmetry of the leaflets. Genes were identified that may contribute to the development of fibrotic AVS. © 2016 American Heart Association, Inc.

  6. Trial design: Rivaroxaban for the prevention of major cardiovascular events after transcatheter aortic valve replacement: Rationale and design of the GALILEO study

    NARCIS (Netherlands)

    Windecker, Stephan; Tijssen, Jan; Giustino, Gennaro; Guimarães, Ana H. C.; Mehran, Roxana; Valgimigli, Marco; Vranckx, Pascal; Welsh, Robert C.; Baber, Usman; van Es, Gerrit-Anne; Wildgoose, Peter; Volkl, Albert A.; Zazula, Ana; Thomitzek, Karen; Hemmrich, Melanie; Dangas, George D.

    2017-01-01

    Optimal antithrombotic treatment after transcatheter aortic valve replacement (TAVR) is unknown and determined empirically. The direct factor Xa inhibitor rivaroxaban may potentially reduce TAVR-related thrombotic complications and premature valve failure. GALILEO is an international, randomized,

  7. Do all hemolytic anemias that occur after mitral valve repair require surgical treatment?

    Science.gov (United States)

    Gungunes, Askin; Akpinar, Ibrahim; Dogan, Mehmet; Baser, Kazim; Yildirim, Ismail Safa; Haznedaroglu, Ibrahim C

    2010-12-01

    We report on a 29-year-old woman with severe hemolytic anemia following mitral valve annuloplasty. Although hemolysis due to mechanical prosthetic mitral valve is well recognized, hemolytic anemia associated with mitral valve repair is an uncommon condition. Reoperation may be considered if the patient has serious and persistent anemia. Although valve replacement is suggested to be a unique intervention, it may not be the solution every time because of mechanical effects. Various mechanisms of hemolysis related to mitral valve repair were suggested, but sufficient and precise data is not available. In this case, we tried to emphasize whether all hemolytic anemias that occur after mitral valve repair require surgical treatment. Copyright © 2010 Wiley Periodicals, Inc.

  8. Maintenance guide for air-operated valves, pneumatic actuators, and accessories

    Energy Technology Data Exchange (ETDEWEB)

    Preckwinkle, S.E. (Fossil Technologies, Inc., Kelso, WA (United States))

    1992-07-01

    Air Operated Valves (AOVs) are used extensively in the power generation industry for process control and system isolation functions. Their proper operation is essential to reliable power plant operation. This guide discusses major components such as actuators, valves, and positioners, and explains the inter-relationship of these components. Diagrams indicating the application and operation of various types of actuators are presented as an aid for thorough investigation of malfunctioning equipment. Recent developments on diagnostic equipment for AOVs are covered and valve traces on valves with maintenance related problems are used to demonstrate how the diagnostic equipment can quickly solve complex valve problems. In addition, predictive and preventive maintenance recommendations based on specific failure data are included. The guide also includes a troubleshooting section with tables providing easily accessible information to minimize troubleshooting costs. Appendices augment the guide by providing a glossary of terms and various engineering schedules including useful engineering parameters for the proper maintenance of air operated valves and accessories.

  9. Deep venous thrombosis: The valve cusp hypoxia thesis and its incompatibility with modern orthodoxy.

    Science.gov (United States)

    Malone, P Colm; Agutter, Paul S

    2016-01-01

    The valve cusp hypoxia thesis (VCHT) of the aetiology of deep venous thrombosis (DVT) was adumbrated in this journal in 1977 and fully articulated in 2008, the original hypothesis having been strongly corroborated by experiments published in 1981 and 1984. It presents a unitary account of the pathogenesis of venous thrombosis and embolism that is rooted in the pathophysiological tradition of Hunter, Virchow, Lister, Welch and Aschoff, a tradition traceable back to Harvey. In this paper we summarise the thesis in its mature form, consider its compatibility with recent advances in the DVT field, and ask why it has not yet been assimilated into the mainstream literature, which during the past half century has been dominated by a haematology-orientated 'consensus model'. We identify and discuss seven ways in which the VCHT is incompatible with these mainstream beliefs about the aetiology of venous thrombosis, drawing attention to: (1) the spurious nature of 'Virchow's triad'; (2) the crucial differences between 'venous thrombus' and 'clot'; the facts that (3) venous thrombi form in the valve pockets (VVPs), (4) DVT is not a primarily haematological condition, (5) the so-called 'thrombophilias' are not thrombogenic per se; (6) the conflict between the single unitary aetiology of DVT and the tacit assumption that the condition is 'multicausal'; (7) the inability of anticoagulants to prevent the initiation of venous thrombogenesis, though they do prevent the growth of thrombi to clinically significant size. In discussing point (7), we show that the VCHT indicates new approaches to mechanical prophylaxis against DVT. These approaches are then formulated as experimentally testable hypotheses, and we suggest methods for testing them preclinically using animal trials. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Valve Repair Is Superior to Replacement in Most Patients With Coexisting Degenerative Mitral Valve and Coronary Artery Diseases.

    Science.gov (United States)

    Javadikasgari, Hoda; Gillinov, A Marc; Idrees, Jay J; Mihaljevic, Tomislav; Suri, Rakesh M; Raza, Sajjad; Houghtaling, Penny L; Svensson, Lars G; Navia, José L; Mick, Stephanie L; Desai, Milind Y; Sabik, Joseph F; Blackstone, Eugene H

    2017-06-01

    For mitral regurgitation (MR) from degenerative mitral disease in patients with coexisting coronary artery disease, the appropriate surgical strategy remains controversial. From 1985 to 2011, 1,071 adults (age 70 ± 9.3 years, 77% men) underwent combined coronary artery bypass grafting and either mitral valve repair (n = 872, 81%) or replacement (n=199, 19%) for degenerative MR. Propensity matching (177 patient pairs, 89% of possible matches) was used to compare early outcomes and time-related recurrence of MR after mitral valve repair, mitral valve reoperation, and mortality. Risk factors for death were identified with multivariable, multiphase hazard-function analysis. Patients undergoing valve replacement were older, with more valve calcification and a higher prevalence of preoperative atrial fibrillation and heart failure (all p < .0001). Among matched pairs, mitral replacement versus repair was associated with higher hospital mortality (5.0% vs 1.0%, p = .0001) and more postoperative renal failure (7.0% vs 3.2%, p = .01), reexplorations for bleeding (6.0% vs 3.1%, p = .05), and respiratory failure (14% vs 4.7%, p < .0001). Of matched patients undergoing repair, 18% had MR above 3+ by 5 years. Mitral valve durability was similar between matched groups, but survival at 15 years was 18% after replacement versus 52% after repair. Nomograms from the multivariable equation revealed that in 94% of cases, 10-year survival was calculated to be higher after repair than after replacement. In patients with coexisting degenerative mitral valve and coronary artery diseases, mitral valve repair is expected to confer a long-term survival advantage over replacement despite some recurrence of MR. When feasible, it is the procedure of choice for these patients. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  11. Covalent surface modification of a titanium alloy with a phosphorylcholine-containing copolymer for reduced thrombogenicity in cardiovascular devices.

    Science.gov (United States)

    Ye, Sang-Ho; Johnson, Carl A; Woolley, Joshua R; Snyder, Trevor A; Gamble, Lara J; Wagner, William R

    2009-10-01

    Our objective was to develop a surface modification strategy for a titanium alloy (TiAl6V4) to provide thromboresistance for surfaces in rigorous blood-contacting cardiovascular applications, such as that found in ventricular assist devices. We hypothesized that this could be accomplished by the covalent attachment of a phospholipid polymer, poly(2-methacryloyloxyethylphosphorylcholine (MPC)-co-methacryl acid) (PMA). TiAl6V4 was H2O plasma treated by radio frequency glow discharge, silanated with 3-aminopropyltriethoxysilane (APS), and ammonia plasma treated to increase surface reactivity. The TiAl6V4 surface was then modified with PMA via a condensation reaction between the amino groups on the TiAl6V4 surface and the carboxyl groups on PMA. The surface composition was verified by X-ray photoelectron spectroscopy, confirming successful modification of the TiAl6V4 surfaces with APS and PMA as evidenced by increased Si and P. Plasma treatments with H2O and ammonia were effective at further increasing the surface reactivity of TiAl6V4 as evidenced by increased surface PMA. The adsorption of ovine fibrinogen onto PMA-modified surfaces was reduced relative to unmodified surfaces, and in vitro ovine blood contact through a rocking test revealed marked reductions in platelet deposition and bulk phase platelet activation relative to unmodified TiAl6V4 and polystyrene controls. The results indicate that the PMA-modification scheme for TiAl6V4 surfaces offers a potential pathway to improve the thromboresistance of the blood-contacting surfaces of cardiovascular devices.

  12. Valve performance concept move from preventive to condition-oriented maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Zanner, G.; Kradepohl, P.

    1996-12-01

    As a turnkey supplier of nuclear and fossil power plants, Siemens must pay attention in concentrating, maintaining, and developing the expertise in many areas such as system design, components, materials, quality assurance, and qualification testing within centralized organizations. In the company segment VALVES, Siemens/KWU is staffed with experienced professionals who have serviced the power plant industry for about 25 years. The valve engineers deal with all kinds of valve and actuator-related activities like design ratings, development, qualifications, and ongoing improvements. In this regard, the engineers are involved in nearly all actual problems and suggested solutions through continuing dialogues with utilities, authorities, and vendors of valves and actuators.

  13. Transcatheter Replacement of Failed Bioprosthetic Valves

    DEFF Research Database (Denmark)

    Simonato, Matheus; Webb, John; Kornowski, Ran

    2016-01-01

    valve mechanism of failure (stenosis/mixed baseline failure: odds ratio, 3.12; confidence interval, 1.51-6.45; P=0.002). Conclusions-High implantation inside failed bioprosthetic valves is a strong independent correlate of lower postprocedural gradients in both self-and balloon-expandable transcatheter......Background-Transcatheter valve implantation inside failed bioprosthetic surgical valves (valve-in-valve [ViV]) may offer an advantage over reoperation. Supra-annular transcatheter valve position may be advantageous in achieving better hemodynamics after ViV. Our objective was to define targets...... for implantation that would improve hemodynamics after ViV. Methods and Results-Cases from the Valve-in-Valve International Data (VIVID) registry were analyzed using centralized core laboratory assessment blinded to clinical events. Multivariate analysis was performed to identify independent predictors of elevated...

  14. Development of an effective valve packing program

    Energy Technology Data Exchange (ETDEWEB)

    Hart, K.A.

    1996-12-01

    Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

  15. Ahmed glaucoma valve implant: surgical technique and complications.

    Science.gov (United States)

    Riva, Ivano; Roberti, Gloria; Oddone, Francesco; Konstas, Anastasios Gp; Quaranta, Luciano

    2017-01-01

    Implantation of Ahmed glaucoma valve is an effective surgical technique to reduce intraocular pressure in patients affected with glaucoma. While in the past, the use of this device was reserved to glaucoma refractory to multiple filtration surgical procedures, up-to-date mounting experience has encouraged its use also as a primary surgery for selected cases. Implantation of Ahmed glaucoma valve can be challenging for the surgeon, especially in patients who already underwent previous multiple surgeries. Several tips have to be acquired by the surgeon, and a long learning curve is always needed. Although the valve mechanism embedded in the Ahmed glaucoma valve decreases the risk of postoperative hypotony-related complications, it does not avoid the need of a careful follow-up. Complications related to this type of surgery include early and late postoperative hypotony, excessive capsule fibrosis around the plate, erosion of the tube or plate edge, and very rarely infection. The aim of this review is to describe surgical technique for Ahmed glaucoma valve implantation and to report related complications.

  16. Sutureless Valves Reduce Hospital Costs Compared to Traditional Valves.

    Science.gov (United States)

    Laborde, François; Folliguet, Thierry; Ghorayeb, Gabriel; Zannis, Konstantinos

    2017-01-01

    The study aim was to assess differences in clinical outcome, safety, and associated costs between sutureless and aortic isolated aortic valve replacement (AVR) with a standard bioprosthesis. A retrospective comparative study was conducted to investigate 65 patients, each of whom had undergone isolated AVR with a traditional aortic valve (T) or a Perceval S sutureless aortic prosthesis (P) between January 2010 and December 2012. Cost data were drawn from the proprietary cost accounting system of the hospital, excluding acquisition costs of the devices. A linear regression model was used to estimate the mean total costs difference between groups. The mean cardiopulmonary bypass time and aortic cross-clamp times in the T and P groups were 80 ± 41 min and 58 ± 26 min versus 38 ± 16 min and 26 ± 10 min, respectively (p costs savings for group P compared to group T were €3,801 (p = 0.13), mainly driven by hospital stay costs. Savings between the P and T groups increased with age: €4,992 in patients aged 70-79 years and €9,326 in those aged 80+ years, and with risk (€4,296 for high-risk patients). Sutureless aortic valves present shorter procedural times and lower hospital costs compared to traditional valves, with higher cost savings at increased patient age and risk. Sutureless aortic valves seem to be cost-effective in patients undergoing AVR.

  17. Robotically assisted mitral valve replacement.

    Science.gov (United States)

    Gao, Changqing; Yang, Ming; Xiao, Cangsong; Wang, Gang; Wu, Yang; Wang, Jiali; Li, Jiachun

    2012-04-01

    In the present study, we determined the safety and efficacy of robotic mitral valve replacement using robotic technology. From January 2007 through March 2011, more than 400 patients underwent various types of robotic cardiac surgery in our department. Of these, 22 consecutive patients underwent robotically assisted mitral valve replacement. Of the 22 patients with isolated rheumatic mitral valve stenosis (9 men and 13 women), the mean age was 44.7 ± 19.8 years (range, 32-65). Preoperatively, all patients underwent a complete workup, including coronary angiography and transthoracic echocardiography. Of the 22 patients, 15 had concomitant atrial fibrillation. The surgical approach was through 4 right-side chest ports with femoral perfusion. Aortic occlusion was performed with a Chitwood crossclamp, and antegrade cardioplegia was administered directly by way of the anterior chest. Using 3 port incisions in the right side of the chest and a 2.5- to 3.0-cm working port, all the procedures were completed with the da Vinci S robot. All patients underwent successful robotic surgery. Of the 22 patients, 16 received a mechanical valve and 6 a tissue valve. The mean cardiopulmonary bypass time and aortic crossclamp time was 137.1 ± 21.9 minutes (range, 105-168) and 99.3 ± 17.9 minutes (range, 80-133), respectively. No operative deaths, stroke, or other complications occurred, and no incisional conversions were required. After surgery, all the patients were followed up echocardiographically. Robotically assisted mitral valve replacement can be performed safely in patients with isolated mitral valve stenosis, and surgical results are excellent. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  18. What Are the Signs and Symptoms of Heart Valve Disease?

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  19. Overview of Prevention for Water Hammer by Check Valve Action in Nuclear Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dayong; Yoon, Hyungi; Seo, Kyoungwoo; Kim, Seonhoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Water hammer can cause serious damage to pumping system and unexpected system pressure rise in the pipeline. In nuclear reactor, water hammer can influence on the integrity of safety related system. Water hammer in nuclear reactor have been caused by voiding in normally water-filled lines, steam condensation line containing both steam and water, as well as by rapid check valve action. Therefore, this study focuses on the water hammer by check valve among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. This study focuses on the water hammer by check valve action among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. If the inadvertent pump trip or pipe rupture in high velocity and pressure pipe is predicted, the fast response check valve such as tiled disc, dual disc and nozzle check valve should be installed in the system. If the inadvertent pump trip or pipe rupture in very high velocity and pressure pipe and excessively large revered flow velocity are predicted, the very slowly closing check valve such as controlled closure check valve should be installed in the system.

  20. Comparison of Modified Chandler, Roller Pump, and Ball Valve Circulation Models for In Vitro Testing in High Blood Flow Conditions: Application in Thrombogenicity Testing of Different Materials for Vascular Applications

    Directory of Open Access Journals (Sweden)

    Wim van Oeveren

    2012-01-01

    We concluded that the Hemobile minimally affects blood and could be adjusted to high blood flows, simulating arterial shear stress. The Hemobile was used to measure hemocompatibility of graft material and showed Dyneema Purity UHMWPE fiber in many ways more hemocompatible than ePTFE and PET.

  1. Increased amount of atrial fibrosis in patients with atrial fibrillation secondary to mitral valve disease

    NARCIS (Netherlands)

    Geuzebroek, Guillaume S. C.; van Amersfoorth, Shirley C. M.; Hoogendijk, Mark G.; Kelder, Johannes C.; van Hemel, Norbert M.; de Bakker, Jacques M. T.; Coronel, Ruben

    2012-01-01

    Objective: Atrial fibrosis is related to atrial fibrillation but may differ in patients with mitral valve disease or lone atrial fibrillation. Therefore, we studied atrial fibrosis in patients with atrial fibrillation + mitral valve disease or with lone atrial fibrillation and compared it with

  2. Experimental results of the tracheoesophageal tissue connector for improved fixation of shunt valves in laryngectomized patients.

    NARCIS (Netherlands)

    Hallers, E.J.O. ten; Marres, H.A.M.; Houwen, E.B. van der; Jansen, J.A.; Rakhorst, G.; Schutte, H.K.; Kooten, T.G. van; Loon, J.P. van; Verkerke, G.J.

    2006-01-01

    BACKGROUND: After total laryngectomy and voice rehabilitation using a tracheoesophageal shunt valve, patients often have valve-related complications such as leakage. To solve these problems, a tracheoesophageal tissue connector (TE-TC) was devised to serve as an interface between the patient's

  3. Chylopericardium After Mitral Valve Repair for Rheumatic Valve Disease Treated with Surgery

    OpenAIRE

    Likaj, Ermal; Kacani, Andi; Dumani, Selman; Dibra, Laureta; Refatllari, Ali

    2014-01-01

    ABSTRACT Chylopericardium is a rare disorder that may be primary (idiopathic) or secondary to injury of the thoracic duct or thymus gland. Pediatric cardiac operations are more commonly related to this complication because thymus gland is very active in this population and atrophies in the adult patients. We present a case of chylopericardium after mitral valve repair for rheumatic disease, due to thymus gland tributaries injury.

  4. Chylopericardium after mitral valve repair for rheumatic valve disease treated with surgery.

    Science.gov (United States)

    Likaj, Ermal; Kacani, Andi; Dumani, Selman; Dibra, Laureta; Refatllari, Ali

    2014-01-01

    Chylopericardium is a rare disorder that may be primary (idiopathic) or secondary to injury of the thoracic duct or thymus gland. Pediatric cardiac operations are more commonly related to this complication because thymus gland is very active in this population and atrophies in the adult patients. We present a case of chylopericardium after mitral valve repair for rheumatic disease, due to thymus gland tributaries injury.

  5. Butterfly valve of all rubber lining type

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Shosaku; Nakatsuma, Sumiya (Kubota Ltd., Osaka (Japan)); Sasaki, Iwao; Aoki, Naoshi

    1982-08-01

    The valves used for the circulating water pipes for condensers in nuclear and thermal power stations have become large with the increase of power output, and their specifications have become strict. The materials for the valves change from cast iron to steel plate construction. To cope with sea water corrosion, rubber lining has been applied to the internal surfaces of valve boxes, and the build-up welding of stainless steel has been made on the edges of valves. However, recently it is desired to develop butterfly valves, of which the whole valve disks are lined with hard rubber. For the purpose of confirming the performance of large bore valves, a 2600 mm bore butterfly valve of all rubber lining type was used, and the opening and closing test of 1100 times was carried out by applying thermal cycle and pressure difference and using artifical sea water. Also the bending test of hard rubber lining was performed with test pieces. Thus, it was confirmed that the butterfly valves of all rubber lining type have the performance exceeding that of the valves with build-up welding. The course of development of the valves of all rubber lining type, the construction and the items of confirmation by tests of these valves, and the tests of the valve and the hard rubber lining described above are reported.

  6. Mitral valve aneurysm associated with aortic valve endocarditis and regurgitation.

    Science.gov (United States)

    Raval, Amish N; Menkis, Alan H; Boughner, Derek R

    2002-01-01

    Mitral valve aneurysms are rare complications occurring most commonly in association with aortic valve infective endocarditis. [Decroly 1989, Chua 1990, Northridge 1991, Karalis 1992, Roguin 1996, Mollod 1997, Vilacosta 1997, Cai 1999, Vilacosta 1999, Teskey 1999, Chan 2000, Goh 2000, Marcos- Alberca 2000] While the mechanism of the development of this lesion is unclear, complications such as perforation can occur and lead to significant mitral regurgitation. [Decroly 1989, Karalis 1992, Teskey 1999, Vilacosta 1999]; The case of a 69-year-old male with Streptococcus Sanguis aortic valve endocarditis and associated anterior mitral leaflet aneurysm is presented. Following surgery, tissue pathology of the excised lesion revealed myxomatous degeneration and no active endocarditis or inflammatory cells. This may add support to the hypothesis that physical stress due to severe aortic insufficiency and structural weakening, without infection of the anterior mitral leaflet, can lead to the development of this lesion.

  7. Valved stent for off-pump mitral valve replacement

    OpenAIRE

    Ma, L.(School of Physics, Shandong University, Shandong, China)

    2004-01-01

    Résumé Objectif : Evaluer un remplacement de valve mitrale hors-pompe avec des stents valvés Méthode: Des homografts préservés dans du glutaraldehyde ont été suturés dans une prothèse tubulaire avant d'être soudés à deux stents Z en nitinol pour créer deux couronnes auto- extensibles. A) Nous avons testé la valve in vitro en utilisant un circuit pulsatile fermé (mock loop) ayant de débuter les expériences sur les porcs. (n=8, 46 .0± 4.3 kg : B). L'oreillette gauche a été exposée p...

  8. Are bioprostheses associated with better outcome than mechanical valves in patients with chronic kidney disease requiring dialysis who undergo valve surgery?

    Science.gov (United States)

    Bianchi, Giacomo; Solinas, Marco; Bevilacqua, Stefano; Glauber, Mattia

    2012-09-01

    valves during the follow-up, while bioprostheses showed an average event rate of 3.9%. All but one of the selected studies reported no differences in survival between mechanical and biological valves; in five of seven studies, the patients who received bioprostheses were older (mechanical vs biological average 53 years vs 61.4 years), in one study, patients had undergone dialysis for longer period of time, and, in another study, they had suffered from more previous myocardial infarction (mechanical vs biological 9.1% vs 36.2%). Therefore, survivals have been biased in favour of mechanical valves. Taking together these data, biological valves are a suitable treatment for dialysis-dependent patients and, while not superior to mechanical valves in survival due to the aforementioned study biases, exhibit lower valve-related and anti-coagulation related events.

  9. Minimally Invasive Heart Valve Surgery.

    Science.gov (United States)

    Bouhout, Ismail; Morgant, Marie-Catherine; Bouchard, Denis

    2017-09-01

    Minimally invasive valve surgery represents a recent and significant advance in modern heart surgery. Indeed, many less invasive approaches for both the aortic and mitral valves have been developed in the past 2 decades. These procedures were hypothesized to result in less operative trauma, which might translate into better patient outcomes. However, this clinical benefit remains controversial in the literature. The aim of this review is to discuss the evidence surrounding minimally invasive heart valve surgery in the current era. A systematic search of the literature from 2006-2016 was performed looking for articles reporting early or late outcomes after minimally invasive valve surgery. Less invasive valve surgery is safe and provides long-term surgical outcomes similar to those of standard sternotomy. In addition, these approaches result in a reduction in overall hospital length of stay and may mitigate the risk of early morbidity-mainly postoperative bleeding, transfusions, and ventilation duration. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  10. Structural valve deterioration in the Mitroflow biological heart valve prosthesis

    DEFF Research Database (Denmark)

    Issa, Issa Farah; Poulsen, Steen Hvitfeldt; Waziri, Farhad

    2018-01-01

    OBJECTIVES: Concern has been raised regarding the long-term durability of the Mitroflow biological heart valve prosthesis. Our aim was to assess the incidence of structural valve degeneration (SVD) for the Mitroflow bioprosthesis in a nationwide study in Denmark including all patients alive...... in Denmark who had received a Mitroflow aortic bioprosthesis since 2000. METHODS: Patients alive in Denmark with a Mitroflow bioprosthesis implanted since January 2000 were invited to participate in a nationwide cross-sectional study with a predefined definition of SVD. Of 1552 patients, 861 patients had...

  11. Development of mechanical heart valves - an inspiring tale

    Directory of Open Access Journals (Sweden)

    P Rajashekar

    2015-01-01

    Full Text Available The historical evolution of the prosthetic heart valves from the first attempts with the Hufnagel′s valve in the treatment of the aortic insufficiency to the Starr-Edwards′ ball valve and later the tilting disc valves (Bjork-Shiley etc., and finally the bileaflet valves (St. Jude are discussed. The Indian contribution with Chitra valve is also described.

  12. Depth profiling of fluorine-doped diamond-like carbon (F-DLC) film: Localized fluorine in the top-most thin layer can enhance the non-thrombogenic properties of F-DLC

    Energy Technology Data Exchange (ETDEWEB)

    Hasebe, Terumitsu [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Department of Radiology, Tachikawa Hospital, 4-2-22, Nishiki-cho, Tachikawa, Tokyo 190-8531 (Japan)], E-mail: teru_hasebe@hotmail.com; Nagashima, So [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Kamijo, Aki [Department of Transfusion Medicine, the University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Yoshimura, Taichi; Ishimaru, Tetsuya; Yoshimoto, Yukihiro; Yohena, Satoshi; Kodama, Hideyuki; Hotta, Atsushi [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Takahashi, Koki [Department of Transfusion Medicine, the University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Suzuki, Tetsuya [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan)

    2007-12-03

    Fluorine-doped diamond-like carbon (F-DLC) has recently drawn a great deal of attention as a more non-thrombogenic coating than conventional DLC for blood-contacting medical devices. We conducted quantitative depth profiling of F-DLC film by X-ray photoelectron spectroscopy (XPS) in order to elucidate the effects of fluorine and fluorine distribution in F-DLC film in connection with the prevention of surface blood adhesion. F-DLC films were prepared on silicon substrates using the radio frequency plasma enhanced chemical vapor deposition method, and the thickness of films was {approx} 50 nm. 50-nm-thick F-DLC film samples were etched at 10-nm thickness intervals using argon plasma, and each surface was examined by XPS. Thereafter, each etched film layer was incubated with platelet-rich plasma isolated from human whole blood, and the platelet-covered area per unit area was evaluated for each surface. XPS spectra showed the localization of doped fluorine in the top-most thin layer of the film. Platelet-covered areas represented progressively larger portions of the surfaces of deeper etched layers, corresponding to the decreasing fluorine content in such sample surfaces. These results indicate that the localized fluorine in the top-most thin layer is one of the key factors in the promotion of the non-thrombogenicity of F-DLC film.

  13. A retrospective analysis of mitral valve pathology in the setting of bicuspid aortic valves

    Science.gov (United States)

    van Rensburg, Annari; Doubell, Anton

    2017-01-01

    The therapeutic implications of bicuspid aortic valve associations have come under scrutiny in the transcatheter aortic valve implantation era. We evaluate the spectrum of mitral valve disease in patients with bicuspid aortic valves to determine the need for closer echocardiographic scrutiny/follow-up of the mitral valve. A retrospective analysis of echocardiograms done at a referral hospital over five years was conducted in patients with bicuspid aortic valves with special attention to congenital abnormalities of the mitral valve. One hundred and forty patients with a bicuspid aortic valve were included. A congenital mitral valve abnormality was present in eight (5.7%, P = 0.01) with a parachute mitral valve in four (2.8%), an accessory mitral valve leaflet in one (0.7%), mitral valve prolapse in one, a cleft in one and the novel finding of a trileaflet mitral valve in one. Minor abnormalities included an elongated anterior mitral valve leaflet (P abnormal papillary muscles (P = 0.002) and an additional chord or tendon in the left ventricle cavity (P = 0.007). Mitral valve abnormalities occur more commonly in patients with bicuspid aortic valves than matched healthy individuals. The study confirms that abnormalities in these patients extend beyond the aorta. These abnormalities did not have a significant functional effect. PMID:28515127

  14. Transcatheter valve-in-valve implantation due to severe aortic regurgitation in a degenerated aortic homograft

    DEFF Research Database (Denmark)

    Olsen, Lene Kjaer; Engstrøm, Thomas; Søndergaard, Lars

    2009-01-01

    a successful valve-in-valve implantation of a CoreValve aortic valve prosthesis through the right subclavian artery in a case of severe aortic regurgitation within a degenerated aortic homograft. The case exemplifies the possibilities of expanding the indications for TAVI, as well as other vascular access...

  15. A retrospective analysis of mitral valve pathology in the setting of bicuspid aortic valves.

    Science.gov (United States)

    van Rensburg, Annari; Herbst, Philip; Doubell, Anton

    2017-06-01

    The therapeutic implications of bicuspid aortic valve associations have come under scrutiny in the transcatheter aortic valve implantation era. We evaluate the spectrum of mitral valve disease in patients with bicuspid aortic valves to determine the need for closer echocardiographic scrutiny/follow-up of the mitral valve. A retrospective analysis of echocardiograms done at a referral hospital over five years was conducted in patients with bicuspid aortic valves with special attention to congenital abnormalities of the mitral valve. One hundred and forty patients with a bicuspid aortic valve were included. A congenital mitral valve abnormality was present in eight (5.7%, P = 0.01) with a parachute mitral valve in four (2.8%), an accessory mitral valve leaflet in one (0.7%), mitral valve prolapse in one, a cleft in one and the novel finding of a trileaflet mitral valve in one. Minor abnormalities included an elongated anterior mitral valve leaflet (P mitral regurgitation (P Mitral valve abnormalities occur more commonly in patients with bicuspid aortic valves than matched healthy individuals. The study confirms that abnormalities in these patients extend beyond the aorta. These abnormalities did not have a significant functional effect. © 2017 The authors.

  16. Should a Regurgitant Mitral Valve Be Replaced Simultaneously with a Stenotic Aortic Valve?

    OpenAIRE

    Christenson, Jan T.; Jordan, Bernard; Bloch, Antoine; Schmuziger, Martin

    2000-01-01

    Mitral valve regurgitation frequently accompanies aortic valve stenosis. It has been suggested that mitral regurgitation improves after aortic valve replacement alone and that the mitral valve need not be replaced simultaneously. Furthermore, mitral regurgitation associated with coronary artery disease, particularly in patients with poor left ventricular function, shows immediate improvement after coronary artery bypass grafting.

  17. Geometry and fusion of aortic valves from pulsatile flow ventricular assist device patients.

    Science.gov (United States)

    May-Newman, Karen; Mendoza, Annamarie; Abulon, Dina J K; Joshi, Mrunalini; Kunda, Anand; Dembitsky, Walter

    2011-03-01

    Aortic valve commissural fusion is a process in which fibrous tissue is deposited at the aortic valve commissures, creating adhesion between leaflets and preventing opening. Fusion has recently been associated with the implantation of left ventricular assist devices (VADs), affecting upwards of 50% of patients in recent studies. Aortic incompetence has also been associated with pulsatile VAD use, but a specific structural mechanism has not been identified. The study aim was to measure aortic valve geometry and fusion in tissue samples from explanted hearts of VAD recipients and to identify features that might explain the development of aortic valve dysfunction. The diameter, perimeter and thickness of the aortic root, as well as the height, edge length and thickness of each of the three aortic leaflets were measured in seven valves. Histological studies were performed of both fused and unfused leaflets. The aortic root geometry showed an elliptical aorta, with asymmetric leaflets. The right coronary leaflet had the greatest edge length, but was thinnest. The other two leaflets were smaller, but slightly thicker. Overall, the aorta and valve geometry was within the normal range. Fusion was found in five of the seven valves studied, and often observed in multiple leaflets. Fusion length correlated loosely with the time of VAD support. Tissue from both fused and unfused valves showed unilateral fibrosis in the leaflets, and a loss of the laminar tissue structure that was related to the duration of VAD support. These findings support previous observations that pathological changes occur in the aortic valves of VAD patients shortly after implantation. While the tissue exhibits abnormalities in the structure, the geometry does not show gross remodeling such as annular dilatation or leaflet lengthening that might precede the development of aortic valve dysfunction. These changes are associated with the development of aortic valve fusion, and may be related to the

  18. Active combustion flow modulation valve

    Science.gov (United States)

    Hensel, John Peter; Black, Nathaniel; Thorton, Jimmy Dean; Vipperman, Jeffrey Stuart; Lambeth, David N; Clark, William W

    2013-09-24

    A flow modulation valve has a slidably translating hollow armature with at least one energizable coil wound around and fixably attached to the hollow armature. The energizable coil or coils are influenced by at least one permanent magnet surrounding the hollow armature and supported by an outer casing. Lorentz forces on the energizable coils which are translated to the hollow armature, increase or decrease the flow area to provide flow throttling action. The extent of hollow armature translation depends on the value of current supplied and the direction of translation depends on the direction of current flow. The compact nature of the flow modulation valve combined with the high forces afforded by the actuator design provide a flow modulation valve which is highly responsive to high-rate input control signals.

  19. Promising results after percutaneous mitral valve repair

    DEFF Research Database (Denmark)

    Ihlemann, Nikolaj; Franzen, Olaf; Jørgensen, Erik

    2011-01-01

    Mitral valve regurgitation (MR) is the secondmost frequent valve disease in Europe. Untreated MR causes considerable morbidity and mortality. In the elderly, as many as half of these patients are denied surgery because of an estimated high surgical risk. Percutaneous mitral valve repair...... with the MitraClip system resembles the Alfieristitch where a clip is used to connect the tip of the mitral valve leaflets....

  20. Infective endocarditis following percutaneous pulmonary valve replacement

    DEFF Research Database (Denmark)

    Cheung, Gary; Vejlstrup, Niels; Ihlemann, Nikolaj

    2013-01-01

    Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult.......Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult....

  1. Pregnancy-induced remodeling of heart valves.

    Science.gov (United States)

    Pierlot, Caitlin M; Moeller, Andrew D; Lee, J Michael; Wells, Sarah M

    2015-11-01

    Recent studies have demonstrated remodeling of aortic and mitral valves leaflets under the volume loading and cardiac expansion of pregnancy. Those valves' leaflets enlarge with altered collagen fiber architecture, content, and cross-linking and biphasic changes (decreases, then increases) in extensibility during gestation. This study extends our analyses to right-sided valves, with additional compositional measurements for all valves. Valve leaflets were harvested from nonpregnant heifers and pregnant cows. Leaflet structure was characterized by leaflet dimensions, and ECM composition was determined using standard biochemical assays. Histological studies assessed changes in cellular and ECM components. Leaflet mechanical properties were assessed using equibiaxial mechanical testing. Collagen thermal stability and cross-linking were assessed using denaturation and hydrothermal isometric tension tests. Pulmonary and tricuspid leaflet areas increased during pregnancy by 35 and 55%, respectively. Leaflet thickness increased by 20% only in the pulmonary valve and largely in the fibrosa (30% thickening). Collagen crimp length was reduced in both the tricuspid (61%) and pulmonary (42%) valves, with loss of crimped area in the pulmonary valve. Thermomechanics showed decreased collagen thermal stability with surprisingly maintained cross-link maturity. The pulmonary leaflet exhibited the biphasic change in extensibility seen in left side valves, whereas the tricuspid leaflet mechanics remained largely unchanged throughout pregnancy. The tricuspid valve exhibits a remodeling response during pregnancy that is significantly diminished from the other three valves. All valves of the heart remodel in pregnancy in a manner distinct from cardiac pathology, with much similarity valve to valve, but with interesting valve-specific responses in the aortic and tricuspid valves. Copyright © 2015 the American Physiological Society.

  2. Pregnancy After Transcatheter Pulmonary Valve Implantation.

    Science.gov (United States)

    Kozicka, Urszula; Weroński, Krzysztof; Rużyłło, Witold; Demkow, Marcin; Kowalski, Mirosław; Śpiewak, Mateusz; Piotrowicz, Ewa; Siudalska, Hanna; Hoffman, Piotr; Biernacka, Elżbieta K

    2017-12-01

    Transcatheter pulmonary valve implantation (TPVI) is a relatively new method of treating patients with significant pulmonary regurgitation or pulmonary stenosis, or both, after reconstruction of the right ventricular outflow tract. It is an attractive alternative to conduit replacement in this group of patients, who are typically young and active. This report includes 4 young women who after successful TPVI became pregnant and gave birth. Transthoracic echocardiography, cardiopulmonary exercise testing, and cardiac magnetic resonance imaging were performed in all patients. The results suggest that pregnancy and delivery after successful TPVI is safe when the appropriate precautions have been taken. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  3. Effects of the blockage ratio of a valve disk on loss coefficient in a butterfly valve

    Energy Technology Data Exchange (ETDEWEB)

    Rho, Hyung Joon; Lee, Jee Keun [Chonbuk National Univ., Jeonju (Korea, Republic of); Choi, Hee Joo [Firstec Co., Ltd., Changwon (Korea, Republic of)

    2008-01-15

    The loss coefficient of the butterfly valve which allows partial opening of the valve at closed position and is applicable to the small-sized pipe system with the diameter of 1 inch was measured for the variation of the valve disk blockage ratio. Two different types of the valve disk configuration to adjust the blockage ratio were considered. One was the solid type valve disk of which the diameter was changed into the smaller size rather than the pipe diameter, and the other was the perforate type valve disk on which some holes were perforated. The results from two types of valve disk were compared to identify their characteristics in the loss coefficient distributions. The loss coefficient and the controllable angle of the valve disk were decreased exponentially with the decrease of the blockage ratio. In addition, the perforate valve disk had the effect on the higher loss coefficient rather than the solid type valve disk.

  4. Double orifice mitral valve; a coincidental finding

    NARCIS (Netherlands)

    Westendorp, Iris C. D.; de Bruin-Bon, H. A. C. M.; Hrudova, Jana

    2006-01-01

    A double orifice mitral valve (DOMV) represents a rare congenital malformation characterised by two valve orifices with two separate subvalvular apparatus. This case demonstrates the necessity of careful imaging of the mitral valve apparatus, not only in patients with atrioventricular septal

  5. Transcatheter mitral valve implantation via transapical approach

    DEFF Research Database (Denmark)

    Sondergaard, Lars; Brooks, Matthew; Ihlemann, Nikolaj

    2015-01-01

    OBJECTIVES: As many as 50% of patients with severe symptomatic mitral valve regurgitation are denied surgical valve replacement or repair due to high operative risk. We describe an early series of cases of transcatheter implantation with a CardiAQ™ mitral valve via a transapical approach. METHODS...

  6. Valve-sparing aortic root replacement†

    NARCIS (Netherlands)

    Koolbergen, David R.; Manshanden, Johan S. J.; Bouma, Berto J.; Blom, Nico A.; Mulder, Barbara J. M.; de Mol, Bas A. J. M.; Hazekamp, Mark G.

    2015-01-01

    To evaluate our results of valve-sparing aortic root replacement and associated (multiple) valve repair. From September 2003 to September 2013, 97 patients had valve-sparing aortic root replacement procedures. Patient records and preoperative, postoperative and recent echocardiograms were reviewed.

  7. Porcine Tricuspid Valve Anatomy and Human Compatibility

    DEFF Research Database (Denmark)

    Waziri, Farhad; Lyager Nielsen, Sten; Hasenkam, J. Michael

    2016-01-01

    before clinical use. The study aim was to evaluate and compare the tricuspid valve anatomy of porcine and human hearts. METHODS: The anatomy of the tricuspid valve and the surrounding structures that affect the valve during a cardiac cycle were examined in detail in 100 fresh and 19 formalin...

  8. Acute Right Coronary Ostial Stenosis during Aortic Valve Replacement

    Directory of Open Access Journals (Sweden)

    Sarwar Umran

    2012-01-01

    Full Text Available We report a rare case of acute right coronary artery stenosis developing in a patient undergoing aortic valve replacement. We present a case report with a brief overview of the literature relating to coronary artery occlusion associated with cardiac valve surgery - the theories and treatments are discussed. A 85 year-old female was admitted under the care of the cardiothoracic team with signs and symptoms of heart failure. Investigations, including cardiac echocardiography and coronary angiography, indicated a critical aortic valve stenosis. Intraoperative right ventricular failure ensued post aortic valve replacement. Subsequent investigations revealed an acute occlusion of the proximal right coronary artery with resultant absence of distal flow supplying the right ventricle. An immediate right coronary artery bypass procedure was performed with resolution of the right ventricular failure. Subsequent weaning off cardiopulmonary bypass was uneventful and the patient continued to make excellent recovery in the postoperative phase. To our knowledge this is one of the few documented cases of intraoperative acute coronary artery occlusion developing during valve surgery. However, surgeons should be aware of the potential for acute occlusion so that early recognition and rapid intervention can be instituted.

  9. Robotic mitral valve surgery: overview, methodology, results, and perspective

    Science.gov (United States)

    2016-01-01

    Robotic mitral valve repair began in 1998 and has advanced remarkably. It arose from an interest in reducing patient trauma by operating through smaller incisions with videoscopic assistance. In the United States, following two clinical trials, the FDA approved the daVinci Surgical System in 2002 for intra-cardiac surgery. This device has undergone three iterations, eventuating in the current daVinci XI. At present it is the only robotic device approved for mitral valve surgery. Many larger centers have adopted its use as part of their routine mitral valve repair armamentarium. Although these operations have longer perfusion and arrest times, complications have been either similar or less than other traditional methods. Preoperative screening is paramount and leads to optimal patient selection and outcomes. There are clear contraindications, both relative and absolute, that must be considered. Three-dimensional (3D) echocardiographic studies optimally guide surgeons in operative planning. Herein, we describe the selection criteria as well as our operative management during a robotic mitral valve repair. Major complications are detailed with tips to avoid their occurrence. Operative outcomes from the author’s series as well as those from the largest experiences in the United States are described. They show that robotic mitral valve repair is safe and effective, as well as economically reasonable due to lower costs of hospitalization. Thus, the future of this operative technique is bright for centers adopting the “heart team” approach, adequate clinical volume and a dedicated and experienced mitral repair surgeon. PMID:27942486

  10. [The Starr-Edwards heart valve: one of the oldest mechanical heart valves still functioning today].

    Science.gov (United States)

    Schoenaker, Michiel H; van Wetten, Herbert B; Morshuis, Wim J

    2015-01-01

    In the 1960s, the Starr-Edwards valve was the first artificial heart valve to be successfully implanted in humans. This valve has now been in use for decades with outstanding results: patients whose life expectancy had previously been short acquired a good prognosis with this development. Nowadays the Starr-Edwards valve is not used anymore, but patients are being described today in whom these valves are still functioning well after more than 40 years.

  11. Effects on fatigue life of gate valves due to higher torque switch settings during operability testing

    Energy Technology Data Exchange (ETDEWEB)

    Richins, W.D.; Snow, S.D.; Miller, G.K.; Russell, M.J.; Ware, A.G.

    1995-12-01

    Some motor operated valves now have higher torque switch settings due to regulatory requirements to ensure valve operability with appropriate margins at design basis conditions. Verifying operability with these settings imposes higher stem loads during periodic inservice testing. These higher test loads increase stresses in the various valve internal parts which may in turn increase the fatigue usage factors. This increased fatigue is judged to be a concern primarily in the valve disks, seats, yokes, stems, and stem nuts. Although the motor operators may also have significantly increased loading, they are being evaluated by the manufacturers and are beyond the scope of this study. Two gate valves representative of both relatively weak and strong valves commonly used in commercial nuclear applications were selected for fatigue analyses. Detailed dimensional and test data were available for both valves from previous studies at the Idaho National Engineering Laboratory. Finite element models were developed to estimate maximum stresses in the internal parts of the valves and to identity the critical areas within the valves where fatigue may be a concern. Loads were estimated using industry standard equations for calculating torque switch settings prior and subsequent to the testing requirements of USNRC Generic Letter 89--10. Test data were used to determine both; (1) the overshoot load between torque switch trip and final seating of the disk during valve closing and (2) the stem thrust required to open the valves. The ranges of peak stresses thus determined were then used to estimate the increase in the fatigue usage factors due to the higher stem thrust loads. The usages that would be accumulated by 100 base cycles plus one or eight test cycles per year over 40 and 60 years of operation were calculated.

  12. Imaging of Cardiac Valves by Computed Tomography

    OpenAIRE

    Gudrun Feuchtner

    2013-01-01

    This paper describes “how to” examine cardiac valves with computed tomography, the normal, diseased valves, and prosthetic valves. A review of current scientific literature is provided. Firstly, technical basics, “how to” perform and optimize a multislice CT scan and “how to” interpret valves on CT images are outlined. Then, diagnostic imaging of the entire spectrum of specific valvular disease by CT, including prosthetic heart valves, is highlighted. The last part gives a guide “how to” use ...

  13. Field Experience with Lock Culvert Valves

    Science.gov (United States)

    2013-12-01

    interesting accounts regarding their lock culvert valves. ST. LAWRENCE SEAWAY Eisenhower and Snell Locks. The valves on the Eisenhower and Snell Locks...Tainter Valve Design Lift, ft Eisenhower St. Lawrence Seaway 80 x 860 12 x 14 21.0 DSP 43 Snell St. Lawrence Seaway 80 x 860 12 x 14 21.0 3 DSP, 1 VF 49...vertical-frame valves were furnished to the SLSDC in January 2011, and one was installed in the south filling-valve location at Snell Lock. An option

  14. Digital valve for high pressure high flow applications

    Science.gov (United States)

    Badescu, Mircea; Sherrit, Stewart; Lewis, Derek; Bao, Xiaoqi; Bar-Cohen, Yoseph; Hall, Jeffery L.

    2016-04-01

    To address the challenges, which are involved with the development of flow control valves that can meet high demand requirements such as high pressure, high flow rate, limited power and limited space, the authors have conceived a novel design configuration. This design consists of a digitalized flow control valve with multipath and multistage pressure reduction structures. Specifically, the valve is configured as a set of parallel flow paths from the inlet to the outlet. A choke valve controls the total flow rate by digitally opening different paths or different combination of the paths. Each path is controlled by a poppet cap valve basically operated in on-off states. The number of flow states is 2N where N is the number of flow paths. To avoid erosion from sand in the fluid and high speed flow, the seal area of the poppet cap valve is located at a distance from the flow inlet away from the high speed flow and the speed is controlled to stay below a predefined erosion safe limit. The path is a multistage structure composed of a set of serial nozzles-expansion chambers that equally distribute the total pressure drop to each stage. The pressure drop of each stage and, therefore, the flow speed at the nozzles and expansion chambers is controlled by the number of stages. The paths have relatively small cross section and could be relatively long for large number of stages and still fit in a strict annular space limit. The paper will present the design configuration, analysis and preliminary test results.

  15. Isolated tricuspid valve infective endocarditis

    African Journals Online (AJOL)

    1990-07-07

    Jul 7, 1990 ... Case 2. Initial chest radiograph showing rounded shadows with cavitation. Fig. 2. Case 2. Chest radiograph showing progression to effusion. nuc/eacum was Isolated from repeated blood cultures. Two- dimensional echocardiography revealed vegetations on the tricuspid valve (Fig. 3). The patient was now ...

  16. Optothermally actuated capillary burst valve

    DEFF Research Database (Denmark)

    Eriksen, Johan; Bilenberg, Brian; Kristensen, Anders

    2017-01-01

    be burst by raising the temperature due to the temperature dependence of the fluid surface tension. We address individual valves by using a local heating platform based on a thin film of near infrared absorber dye embedded in the lid used to seal the microfluidic device [L. H. Thamdrup et al., Nano Lett...

  17. Mitral valve surgery - minimally invasive

    Science.gov (United States)

    ... be able to store blood in the blood bank for transfusions during and after your surgery. Ask ... Mechanical heart valves do not fail often. However, blood clots can develop on them. If a blood clot forms, you may have a stroke. Bleeding can occur, ...

  18. Aortic valve surgery - minimally invasive

    Science.gov (United States)

    ... be able to store blood in the blood bank for transfusions during and after your surgery. Ask ... Mechanical heart valves do not fail often. However, blood clots can develop on them. If a blood clot forms, you may have a stroke. Bleeding can occur, ...

  19. Hemodynamics driven cardiac valve morphogenesis.

    Science.gov (United States)

    Steed, Emily; Boselli, Francesco; Vermot, Julien

    2016-07-01

    Mechanical forces are instrumental to cardiovascular development and physiology. The heart beats approximately 2.6 billion times in a human lifetime and heart valves ensure that these contractions result in an efficient, unidirectional flow of the blood. Composed of endocardial cells (EdCs) and extracellular matrix (ECM), cardiac valves are among the most mechanically challenged structures of the body both during and after their development. Understanding how hemodynamic forces modulate cardiovascular function and morphogenesis is key to unraveling the relationship between normal and pathological cardiovascular development and physiology. Most valve diseases have their origins in embryogenesis, either as signs of abnormal developmental processes or the aberrant re-expression of fetal gene programs normally quiescent in adulthood. Here we review recent discoveries in the mechanobiology of cardiac valve development and introduce the latest technologies being developed in the zebrafish, including live cell imaging and optical technologies, as well as modeling approaches that are currently transforming this field. 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. Copyright © 2015. Published by Elsevier B.V.

  20. Sequential transcatheter aortic valve implantation due to valve dislodgement - a Portico valve implanted over a CoreValve bioprosthesis

    DEFF Research Database (Denmark)

    Campante Teles, Rui; Costa, Cátia; Almeida, Manuel

    2017-01-01

    Transcatheter aortic valve implantation (TAVI) has become an important treatment in high surgical risk patients with severe aortic stenosis (AS), whose complications need to be managed promptly. The authors report the case of an 86-year-old woman presenting with severe symptomatic AS, rejected fo...

  1. What Is Heart Valve Surgery?

    Science.gov (United States)

    ... called stenosis). • Don’t close properly and let blood leak where it shouldn’t. This is called incompetence, insufficiency or regurgitation. • Prolapse — mitral valve flaps don’t close properly (more common in women).As pressure builds inside the left ventricle, it pushes the ...

  2. An improved gate valve for critical applications in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Kalsi, M.S.; Alvarez, P.D.; Wang, J.K.; Somagyi, D. [Kalsi Engineering, Inc., Sugar Land, TX (United States)] [and others

    1996-12-01

    U.S. Nuclear Regulatory Commission Generic Letters 89-10 for motor-operated valves (MOVs) and 95-07 for all power-operated valves document in detail the problems related to the performance of the safety-related valves in nuclear power plants. The problems relate to lack of reliable operation under design basis conditions including higher than anticipated stem thrust, unpredictable valve behavior, damage to the valve internals under blowdown/high flow conditions, significant degradation of performance when cycled under AP and flow, thermal binding, and pressure locking. This paper describes an improved motor-operated flexible wedge gate valve design, the GE Sentinel Valve, which is the outcome of a comprehensive and systematic development effort undertaken to resolve the issues identified in the NRC Generic Letters 89-10 and 95-07. The new design provides a reliable, long-term, low maintenance cost solution to the nuclear power industry. One of the key features incorporated in the disc permits the disc flexibility to be varied independently of the disc thickness (pressure boundary) dictated by the ASME Section III Pressure Vessel & Piping Code stress criteria. This feature allows the desired flexibility to be incorporated in the disc, thus eliminating thermal binding problems. A matrix of analyses was performed using finite element and computational fluid dynamics approaches to optimize design for stresses, flexibility, leak-tightness, fluid flow, and thermal effects. The design of the entire product line was based upon a consistent set of analyses and design rules which permit scaling to different valve sizes and pressure classes within the product line. The valve meets all of the ASME Section III Code design criteria and the N-Stamp requirements. The performance of the valve was validated by performing extensive separate effects and plant in-situ tests. This paper summarizes the key design features, analyses, and test results.

  3. Manufacturable plastic microfluidic valves using thermal actuation.

    Science.gov (United States)

    Pitchaimani, Karthik; Sapp, Brian C; Winter, Adam; Gispanski, Austin; Nishida, Toshikazu; Hugh Fan, Z

    2009-11-07

    A low-cost, manufacturable, thermally actuated, plastic microfluidic valve has been developed. The valve contains an encapsulated, temperature-sensitive fluid, which expands, deflecting a thin elastomeric film into a fluidic channel to control fluid flow. The power input for thermal expansion of each microfluidic valve can be controlled using a printed circuit board (PCB)-based controller, which is suitable for mass production and large-scale integration. A plastic microfluidic device with such valves was fabricated using compression molding and thermal lamination. The operation of the valves was investigated by measuring a change in the microchannel's ionic conduction current mediated by the resistance variation corresponding to the deflection of the microvalve. Valve closing was also confirmed by the disappearance of fluorescence when a fluorescent solution was displaced in the valve region. Valve operation was characterized for heater power ranging from 36 mW to 80 mW. When the valve was actuating, the local channel temperature was 10 to 19 degrees C above the ambient temperature depending on the heater power used. Repetitive valve operations (up to 50 times) have been demonstrated with a flow resulting from a hydrostatic head. Valve operation was tested for a flow rate of 0.33-4.7 microL/min.

  4. Presence of Coxiella burnetii DNA in inflamed bovine cardiac valves

    DEFF Research Database (Denmark)

    Agerholm, Jørgen S.; Jensen, Tim Kåre; Agger, Jens F.

    2017-01-01

    is relatively common in cattle affected with valvular endocarditis. The role of C. burnetii remains however unknown as lesions did not differ between C. burnetii infected and non-infected cattle and because T. pyogenes-like bacteria were present in the inflamed valves; a bacterium able to induce the observed...

  5. Mitral Valve Disease: a Comprehensive Review.

    Science.gov (United States)

    Harb, Serge C; Griffin, Brian P

    2017-08-01

    This review aims to provide a comprehensive assessment of mitral valve disease, both mitral stenosis and mitral regurgitation, starting with an overview of the valve anatomy. The advent of three-dimensional imaging has allowed a better representation of the valve anatomy. Rheumatic disease is still the number one cause of mitral stenosis worldwide and percutaneous balloon mitral valvuloplasty remains the therapy of choice when indicated and in anatomically eligible patients. Mitral regurgitation (MR) is classified as primary (i.e., lesion in the mitral apparatus) or secondary (caused by left ventricular geometrical alterations). While surgery, preferably repair, is still the recommended therapy for severe primary MR, percutaneous approaches to repair and/or replace the mitral valve are being extensively investigated. Mitral valve disease is common. A careful understanding of mitral valve anatomy and the disease processes that affect the valve are crucial for providing optimal patient care.

  6. Mitral Valve Repair: The Chordae Tendineae

    Directory of Open Access Journals (Sweden)

    Carlos-A Mestres

    2015-10-01

    Full Text Available Repair of the mitral valve is the treatment of choice for mitral valve regurgitation when the anatomy is favorable. It is well known that mitral valve repair enjoys better clinical and functional results than any other type of valve substitute. This fact is beyond doubt regardless of the etiology of the valve lesion and is of particular importance in degenerative diseases.This review analyzes the most important advances in the knowledge of the anatomy, pathophysiology, and chordal function of the mitral valve as well as the different alternatives in the surgical repair and clinical results of the most prevalent diseases of the mitral valve. An attempt has been made to organize the acquired information available in a practical way.

  7. Development and experimental characterization of a pneumatic valve actuated by a dielectric elastomer membrane

    Science.gov (United States)

    Hill, Marc; Rizzello, Gianluca; Seelecke, Stefan

    2017-08-01

    Due to their many features including lightweight and low energy consumption, dielectric elastomer (DE) membrane actuators are of interest for a number of industrial applications, such as pumping systems or valve control units. In particular, the use of DEs in valve control units offers advantages over traditional solenoid valves, including lower power requirements and relative simplicity in achieving proportional control. Additionally, DEs generate low thermal dissipation and are capable of virtually silent operation. The contribution of this work is the development of a new valve system based on a circular DE membrane pre-loaded with a linear spring. The valve is designed for pressurized air and operates by actuating a lever mechanism that opens and closes an outlet port. After presenting the operating principle and system design, several experiments are presented to compare actuator force, stroke, and dissipated energy for several pressure differentials and associated volume flows. It is observed that the DE-driven valve achieves a performance similar to a solenoid-based valve, while requiring a significantly lower amount of input energy. In addition, it is shown that DE-membrane valves can be controlled proportionally by simply adjusting the actuator voltage.

  8. Experimental study on the effect of an artificial cardiac valve on the left ventricular flow

    Science.gov (United States)

    Wang, JiangSheng; Gao, Qi; Wei, RunJie; Wang, JinJun

    2017-09-01

    The use of artificial valves to replace diseased human heart valves is currently the main solution to address the malfunctioning of these valves. However, the effect of artificial valves on the ventricular flow still needs to be understood in flow physics. The left ventricular flow downstream of a St. Jude Medical (SJM) bileaflet mechanical heart valve (BMHV), which is a widely implanted mechanical bileaflet valve, is investigated with time-resolved particle image velocimetry in the current work. A tilting-disk valve is installed on the aortic orifice to guarantee unidirectional flow. Several post-processing tools are applied to provide combined analyses of the physics involved in the ventricular flow. The triple jet pattern that is closely related to the characteristics of the bileaflet valve is discussed in detail from both Eulerian and Lagrangian views. The effects of large-scale vortices on the transportation of blood are revealed by the combined analysis of the tracking of Lagrangian coherent structures, the Eulerian monitoring of the shear stresses, and virtual dye visualization. It is found that the utilization of the SJM BMHV complicates the ventricular flow and could reduce the efficiency of blood transportation. In addition, the kinematics of the bileaflets is presented to explore the effects of flow structures on their motion. These combined analyses could elucidate the properties of SJM BMHV. Furthermore, they could provide new insights into the understanding of other complex blood flows.

  9. Scleraxis is required for cell lineage differentiation and extracellular matrix remodeling during murine heart valve formation in vivo.

    Science.gov (United States)

    Levay, Agata K; Peacock, Jacqueline D; Lu, Yinhui; Koch, Manuel; Hinton, Robert B; Kadler, Karl E; Lincoln, Joy

    2008-10-24

    Heart valve structures, derived from mesenchyme precursor cells, are composed of differentiated cell types and extracellular matrix arranged to facilitate valve function. Scleraxis (scx) is a transcription factor required for tendon cell differentiation and matrix organization. This study identified high levels of scx expression in remodeling heart valve structures at embryonic day 15.5 through postnatal stages using scx-GFP reporter mice and determined the in vivo function using mice null for scx. Scx(-/-) mice display significantly thickened heart valve structures from embryonic day 17.5, and valves from mutant mice show alterations in valve precursor cell differentiation and matrix organization. This is indicated by decreased expression of the tendon-related collagen type XIV, increased expression of cartilage-associated genes including sox9, as well as persistent expression of mesenchyme cell markers including msx1 and snai1. In addition, ultrastructure analysis reveals disarray of extracellular matrix and collagen fiber organization within the valve leaflet. Thickened valve structures and increased expression of matrix remodeling genes characteristic of human heart valve disease are observed in juvenile scx(-/-) mice. In addition, excessive collagen deposition in annular structures within the atrioventricular junction is observed. Collectively, our studies have identified an in vivo requirement for scx during valvulogenesis and demonstrate its role in cell lineage differentiation and matrix distribution in remodeling valve structures.

  10. Endothelial Microparticles From Acute Coronary Syndrome Patients Induce Premature Coronary Artery Endothelial Cell Aging and Thrombogenicity: Role of the Ang II/AT1 Receptor/NADPH Oxidase-Mediated Activation of MAPKs and PI3-Kinase Pathways.

    Science.gov (United States)

    Abbas, Malak; Jesel, Laurence; Auger, Cyril; Amoura, Lamia; Messas, Nathan; Manin, Guillaume; Rumig, Cordula; León-González, Antonio J; Ribeiro, Thais P; Silva, Grazielle C; Abou-Merhi, Raghida; Hamade, Eva; Hecker, Markus; Georg, Yannick; Chakfe, Nabil; Ohlmann, Patrick; Schini-Kerth, Valérie B; Toti, Florence; Morel, Olivier

    2017-01-17

    Microparticles (MPs) have emerged as a surrogate marker of endothelial dysfunction and cardiovascular risk. This study examined the potential of MPs from senescent endothelial cells (ECs) or from patients with acute coronary syndrome (ACS) to promote premature EC aging and thrombogenicity. Primary porcine coronary ECs were isolated from the left circumflex coronary artery. MPs were prepared from ECs and venous blood from patients with ACS (n=30) and from healthy volunteers (n=4) by sequential centrifugation. The level of endothelial senescence was assessed as senescence-associated β-galactosidase activity using flow cytometry, oxidative stress using the redox-sensitive probe dihydroethidium, tissue factor activity using an enzymatic Tenase assay, the level of target protein expression by Western blot analysis, platelet aggregation using an aggregometer, and shear stress using a cone-and-plate viscometer. Senescence, as assessed by senescence-associated β-galactosidase activity, was induced by the passaging of porcine coronary artery ECs from passage P1 to P4, and was associated with a progressive shedding of procoagulant MPs. Exposure of P1 ECs to MPs shed from senescent P3 cells or circulating MPs from ACS patients induced increased senescence-associated β-galactosidase activity, oxidative stress, early phosphorylation of mitogen-activated protein kinases and Akt, and upregulation of p53, p21, and p16. Ex vivo, the prosenescent effect of circulating MPs from ACS patients was evidenced only under conditions of low shear stress. Depletion of endothelial-derived MPs from ACS patients reduced the induction of senescence. Prosenescent MPs promoted EC thrombogenicity through tissue factor upregulation, shedding of procoagulant MPs, endothelial nitric oxide synthase downregulation, and reduced nitric oxide-mediated inhibition of platelet aggregation. These MPs exhibited angiotensin-converting enzyme activity and upregulated AT1 receptors and angiotensin

  11. Conical Seat Shut-Off Valve

    Science.gov (United States)

    Farner, Bruce

    2013-01-01

    A moveable valve for controlling flow of a pressurized working fluid was designed. This valve consists of a hollow, moveable floating piston pressed against a stationary solid seat, and can use the working fluid to seal the valve. This open/closed, novel valve is able to use metal-to-metal seats, without requiring seat sliding action; therefore there are no associated damaging effects. During use, existing standard high-pressure ball valve seats tend to become damaged during rotation of the ball. Additionally, forces acting on the ball and stem create large amounts of friction. The combination of these effects can lead to system failure. In an attempt to reduce damaging effects and seat failures, soft seats in the ball valve have been eliminated; however, the sliding action of the ball across the highly loaded seat still tends to scratch the seat, causing failure. Also, in order to operate, ball valves require the use of large actuators. Positioning the metal-to-metal seats requires more loading, which tends to increase the size of the required actuator, and can also lead to other failures in other areas such as the stem and bearing mechanisms, thus increasing cost and maintenance. This novel non-sliding seat surface valve allows metal-to-metal seats without the damaging effects that can lead to failure, and enables large seating forces without damaging the valve. Additionally, this valve design, even when used with large, high-pressure applications, does not require large conventional valve actuators and the valve stem itself is eliminated. Actuation is achieved with the use of a small, simple solenoid valve. This design also eliminates the need for many seals used with existing ball valve and globe valve designs, which commonly cause failure, too. This, coupled with the elimination of the valve stem and conventional valve actuator, improves valve reliability and seat life. Other mechanical liftoff seats have been designed; however, they have only resulted in

  12. Clinical performance of mechanical versus bioprosthetic valves in patients aged 60-70 years

    Directory of Open Access Journals (Sweden)

    Si-ming ZHU

    2017-06-01

    Full Text Available Objective To compare the mortality, valve-related morbidity and reoperation rate between mechanical prostheses and bioprostheses in patients aged 60 to 70 years. Methods The pre-operative characteristics of 119 patients who received mechanical prostheses and 181 those with bioprosthesis implantation in our department between January 2006 and December 2014 were analyzed, and their mortality, valve-related morbidity and reoperation rate were compared. Results Follow-up revealed mechanical prostheses had a lower all-cause mortality after mitral valve replacement than bioprostheses at 6 years after the operation (P=0.033, but there was no statistical difference in valve-related mortality (P=0.277. The complications after mechanical prosthesis replacement had embolism (8.4% and bleeding (5.0%, bioprosthesis' those consisted of structural valvular deterioration (2.2%, nonstructural dysfunction (1.1%, thrombosis (2.8%, embolism (5.0%, bleeding (0.6% and operated valvular endocarditis (1.1%. There was no statistically significant difference in total complication rate between the two groups (P=0.318. Biological group had 3 patients receiving reoperation in 8 years, while there was no reoperation in the mechanical group, but without statistical group difference. Conclusion Patients aged 60-70 years old could have a similar valve-related mortality, morbidity and reoperation rate after mitral valve replacement between mechanical and biological valves. DOI: 10.11855/j.issn.0577-7402.2017.05.19

  13. Kangaroo vs. porcine aortic valves: calcification potential after glutaraldehyde fixation.

    Science.gov (United States)

    Narine, K; Chéry, Cyrille C; Goetghebeur, Els; Forsyth, R; Claeys, E; Cornelissen, Maria; Moens, L; Van Nooten, G

    2005-01-01

    The aim of this study was to evaluate and compare the calcification potential of kangaroo and porcine aortic valves after glutaraldehyde fixation at both low (0.6%) and high (2.0%) concentrations of glutaraldehyde in the rat subcutaneous model. To our knowledge this is the first report comparing the time-related, progressive calcification of these two species in the rat subcutaneous model. Twenty-two Sprague-Dawley rats were each implanted with two aortic valve leaflets (porcine and kangaroo) after fixation in 0.6% glutaraldehyde and two aortic valve leaflets (porcine and kangaroo) after fixation in 2% glutaraldehyde respectively. Animals were sacrificed after 24 h and thereafter weekly for up to 10 weeks after implantation. Calcium content was determined using inductively coupled plasma-mass spectrometry and confirmed histologically. Mean calcium content per milligram of tissue (dry weight) treated with 0.6 and 2% glutaraldehyde was 116.2 and 110.4 microg/mg tissue for kangaroo and 95.0 and 106.8 microg/mg tissue for porcine valves. Calcium content increased significantly over time (8.8 microg/mg tissue per week) and was not significantly different between groups. Regression analysis of calcification over time showed no significant difference in calcification of valves treated with 0.6 or 2% glutaraldehyde within and between the two species. Using the subcutaneous model, we did not detect a difference in calcification potential between kangaroo and porcine aortic valves treated with either high or low concentrations of glutaraldehyde. Copyright 2005 S. Karger AG, Basel.

  14. A New Hemostasis Valve for Neuroendovascular Procedures

    Science.gov (United States)

    Namba, K.; Song, J.K.; Niimi, Y.; Heran, N.S.; Berenstein, A.

    2007-01-01

    Summary A hemostasis valve is routinely used in neuroendovascular procedures to decrease the risk of thromboembolism1,2. Recently, a new hemostasis valve that is designed to minimize blood loss has been introduced. We report our initial experience in using this new hemostasis valve. In neuroendovascular procedures, a hemostasis valve is commonly used for continuous irrigation of guide and microcatheters to decrease the risk of thromboembolism1,2,3. A conventional hemostasis valve has a rotating seal at the end, which is turned open or closed each time a wire or microcatheter/guidewire is introduced or extracted. Often this results in significant back bleeding. When a rotating seal is adjusted suboptimally during a wire or microcatheter manipulation, leakage of pressurized saline from the end of a hemostasis valve results in stagnation of blood within a guiding catheter, which becomes a potential source of emboli during a procedure. The Guardian Haemostasis Valve (Zerusa Limited, Galway, Ireland) is a new hemostasis valve that is designed to minimize blood loss during interventional procedures by minimizing the opening time of the valve during wire or microcatheter insertion. A continuous sealing mechanism during wire or microcatheter positioning minimizes blood loss and stagnation of blood within the guide catheter. We report our initial experience with the Guardian hemostasis valve. PMID:20566129

  15. Transcatheter aortic valve-in-valve implantation of a CoreValve in a JenaValve prosthesis: a case report.

    Science.gov (United States)

    Lotfi, Shahram; Becker, Michael; Moza, Ajay; Autschbach, Rüdiger; Marx, Nikolaus; Schröder, Jörg

    2017-09-10

    Transcatheter aortic valve implantation has become an accepted treatment modality for inoperable or high-risk surgical patients with symptomatic severe aortic stenosis. We report the case of a 70-year-old white man who was treated for severe symptomatic aortic regurgitation using transcatheter aortic valve implantation from the apical approach. Because of recurrent cardiac decompensation 4 weeks after implantation he underwent the implantation of a left ventricular assist device system. A year later echocardiography showed a severe transvalvular central insufficiency. Our heart team decided to choose a valve-in-valve approach while reducing the flow rate of left ventricular assist device to minimum and pacing with a frequency of 140 beats/minute. There was an excellent result and our patient is doing well with no relevant insufficiency of the aortic valve at 12-month follow-up. This is the first report about a successful treatment of a stenotic JenaValve using a CoreValve Evolut R; the use of a CoreValve Evolut R prosthesis may be an optimal option for valve-in-valve procedures.

  16. Contemporary outcomes in reoperative mitral valve surgery.

    Science.gov (United States)

    Mehaffey, Hunter J; Hawkins, Robert B; Schubert, Sarah; Fonner, Clifford; Yarboro, Leora T; Quader, Mohammed; Speir, Alan; Rich, Jeff; Kron, Irving L; Ailawadi, Gorav

    2017-10-05

    Data suggest that redo mitral valve surgery is being performed in increasing numbers, possibly with superior results according to single-centre studies. The purpose of this study is to describe outcomes of redo mitral valve surgery and identify risk-adjusted predictors of poor outcomes. All (11 973) open mitral valve cases were evaluated (2002-2016) from a regional Society of Thoracic Surgery (STS) database. Patients were stratified by primary versus redo mitral valve surgery. Mixed effects logistic regression models including hospital as a random effect were used to identify risk factors for patients undergoing redo mitral valve surgery. Of all mitral valve cases, 1096 (9.7%) had a previous mitral operation. Redo patients had higher rates of valve replacement and preoperative comorbidities resulting in more complications, operative mortalities (11.1%vs6.5%, pmitral valve surgery increased 10% per year and the observed-to-expected ratios (O/E) for operative mortality in redo mitral surgery improved from 1.44 early in the study period to 0.72 in the most recent era. Redo mitral valve surgery accounts for approximately 10% of mitral valve operations and is associated with increased risk and resource utilisation. However, as the volume of redo mitral surgery increases, outcomes have dramatically improved and are now better than predicted. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  17. Traumatic Mitral Valve and Pericardial Injury

    Directory of Open Access Journals (Sweden)

    Nissar Shaikh

    2013-01-01

    Full Text Available Cardiac injury after blunt trauma is common but underreported. Common cardiac trauma after the blunt chest injury (BCI is cardiac contusion; it is very rare to have cardiac valve injury. The mitral valve injury during chest trauma occurs when extreme pressure is applied at early systole during the isovolumic contraction between the closure of the mitral valve and the opening of the aortic valve. Traumatic mitral valve injury can involve valve leaflet, chordae tendineae, or papillary muscles. For the diagnosis of mitral valve injury, a high index of suspicion is required, as in polytrauma patients, other obvious severe injuries will divert the attention of the treating physician. Clinical picture of patients with mitral valve injury may vary from none to cardiogenic shock. The echocardiogram is the main diagnostic modality of mitral valve injuries. Patient’s clinical condition will dictate the timing and type of surgery or medical therapy. We report a case of mitral valve and pericardial injury in a polytrauma patient, successfully treated in our intensive care unit.

  18. Experiments and Valve Modelling in Thermoacoustic Device

    Science.gov (United States)

    Duthil, P.; Baltean Carlès, D.; Bétrancourt, A.; François, M. X.; Yu, Z. B.; Thermeau, J. P.

    2006-04-01

    In a so called heat driven thermoacoustic refrigerator, using either a pulse tube or a lumped boost configuration, heat pumping is induced by Stirling type thermodynamic cycles within the regenerator. The time phase between acoustic pressure and flow rate throughout must then be close to that met for a purely progressive wave. The study presented here relates the experimental characterization of passive elements such as valves, tubes and tanks which are likely to act on this phase relationship when included in the propagation line of the wave resonator. In order to carry out a characterization — from the acoustic point of view — of these elements, systematic measurements of the acoustic field are performed varying various parameters: mean pressure, oscillations frequency, supplied heat power. Acoustic waves are indeed generated by use of a thermoacoustic prime mover driving a pulse tube refrigerator. The experimental results are then compared with the solutions obtained with various one-dimensional linear models including non linear correction factors. It turns out that when using a non symmetrical valve, and for large dissipative effects, the measurements disagree with the linear modelling and non linear behaviour of this particular element is shown.

  19. Weaving for heart valve tissue engineering.

    Science.gov (United States)

    Liberski, Albert; Ayad, Nadia; Wojciechowska, Dorota; Kot, Radoslaw; Vo, Duy M P; Aibibu, Dilibaier; Hoffmann, Gerald; Cherif, Chokri; Grobelny-Mayer, Katharina; Snycerski, Marek; Goldmann, Helmut

    2017-11-01

    Weaving is a resourceful technology which offers a large selection of solutions that are readily adaptable for tissue engineering (TE) of artificial heart valves (HV). The different ways that the yarns are interlaced in this technique could be used to produce complex architectures, such as the three-layer architecture of the leaflets. Once the assembly is complete, growth of cells in the scaffold would occur in the orientation of the yarn, enabling the deposition of extra cellular matrixes proteins in an oriented manner. Weaving technology is a rapidly evolving field that, first, needs to be understood, and then explored by tissue engineers, so that it could be used to create efficient scaffolds. Similarly, the textile engineers need to gain a basic understanding of key structural and mechanical aspects of the heart valve. The aim of this review is to provide the platform for joining these two fields and to enable cooperative research efforts. Moreover, examples of woven medical products and patents as well as related publication are discussed in this review, nevertheless due to the large, and continuously growing volume of data, only the aspects strictly associated with HVTE lay in the scope of this paper. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Morbidity and mortality of nonagenarians undergoing CoreValve implantation

    Directory of Open Access Journals (Sweden)

    Akin Ibrahim

    2012-09-01

    elevated comorbidity index, clinical endpoints and valve-associated results are relatively favorable in nonagenarians treated with CoreValve.

  1. Tricuspid valve endocarditis caused by Haemophilus parainfluenzae: a case report and review of the literature.

    Science.gov (United States)

    Nwaohiri, Nnamdi; Urban, Carl; Gluck, Jason; Ahluwalia, Maneesha; Wehbeh, Wehbeh

    2009-06-01

    Haemophilus parainfluenzae is a Gram-negative bacterium that is often difficult to isolate and identify. We report a rare case of tricuspid valve and pacemaker endocarditis caused by this organism and explore factors related to etiopathogenesis, prevention, and treatment.

  2. Twenty years' single-center experience with mechanical heart valves: a critical review of anticoagulation policy.

    Science.gov (United States)

    Van Nooten, Guido J; Caes, Frank; François, Katrien; Van Bellleghem, Yves; Bové, Thierry; Vandenplas, Guy; Taeymans, Yves

    2012-01-01

    Since January 1990, a variety of mechanical valves (St. Jude Medical, CarboMedics, ATS Medical) have been implanted routinely at the authors' institution. The study aim was to analyze, retrospectively, the 20-year clinical results of those mechanical valves, and to challenge the anticoagulation policy employed over the years. Between January 1990 and December 2008, a total of 2,108 mechanical valves was inserted into 1,887 consecutive patients (1,346 aortic, 725 mitral, 27 tricuspid, 10 pulmonary). The mean age of the patients was 63 +/- 13.2 years, and the majority (61%) were males. Preoperatively, 71% the patients were in NYHA class > or = III (average 3.01). The most frequent comorbidities included: atrial fibrillation (n = 594), coronary disease (n = 567) and diabetes (n = 398). The follow up (99% complete) totaled 13,721 patient-years (pt-yr), and ranged from 12 to 241 months (average 84 months). In-hospital mortality was 5.2% (n = 98, 14 valve-related). Of the 629 late deaths, the majority were cardiac (n = 276). Survival (Kaplan-Meier estimation) was significantly better for aortic valve patients compared to mitral or multiple valve replacement (Mantel-Cox, p valve thrombosis 0.31, thromboembolism 1.08, and bleeding 0.91. However, as repeated events occurred in several patients, the hazard function was not constant. Multivariate analysis (Cox regression model) showed age > 70 years (p or = III (p II as significant risk factors for thromboembolism, while long-acting coumadin and NYHA class > II were significant risk factors for bleeding. This 20-year experience demonstrated excellent clinical outcomes for patients with mechanical prostheses, with no valve structural failure and an acceptable incidence of adverse events. INR values between 2-2.5 for aortic valve patients, and 3-3.5 for mitral valve patients, yielded the fewest major adverse events.

  3. Flow Characteristics of Butterfly Valve by PIV and CFD

    Science.gov (United States)

    Kim, S. W.; Kim, J. H.; Choi, Y. D.; Lee, Y. H.

    Butterfly valves are widely used as on-off and control valves for industrial process. The importance of butterfly valves as control valves has been increasing because the pressure loss is smaller than other types of valves and compactness is very desirable for installation. These features are desirable for saving energy and high efficiency of instruments.

  4. Mechanical valves in the pulmonary position : An international retrospective analysis

    NARCIS (Netherlands)

    Pragt, Hanna; van Melle, Joost P.; Javadikasgari, Hoda; Seo, Dong Man; Stulak, John M.; Knez, Igor; Hoerer, Juergen; Munoz-Guijosa, Christian; Dehaki, Mahyar G.; Shin, Hong Ju; Dearani, Joseph A.; Dehaki, Maziar G.; Pieper, Petronella G.; Eulenburg, Christine; Dos, Laura; Ebels, Tjark

    2017-01-01

    Objective: Life expectancy of patients with congenital heart disease has improved over the past decades, increasing the need for a durable pulmonary prosthetic valve. Biological valves in various forms have become the valve of choice for pulmonary valve replacement (PVR), but structural valve

  5. Aerococcus viridans Native Valve Endocarditis

    Directory of Open Access Journals (Sweden)

    Wenwan Zhou

    2013-01-01

    Full Text Available Aerococcus viridans is an infrequent human pathogen and few cases of infective endocarditis have been reported. A case involving a 69-year-old man with colon cancer and hemicolectomy 14 years previously, without recurrence, is reported. A diagnosis of native mitral valve endocarditis was established on the basis of clinical presentation, characteristic echocardiographic findings and pathological specimen examination after urgent valve replacement. A viridans endocarditis appears to be particularly virulent, requiring a surgical approach in four of 10 cases reported and death in one of nine. Given the aggressive nature of A viridans endocarditis and the variable time to diagnosis (a few days to seven months, prompt recognition of symptoms and echocardiography, in addition to blood cultures, should be performed when symptoms persist.

  6. Development of Long-Lifetime Pulsed Gas Valves for Pulsed Electric Thrusters

    Science.gov (United States)

    Burkhardt, Wendel M.; Crapuchettes, John M.; Addona, Brad M.; Polzin, Kurt A.

    2015-01-01

    even 10(exp 9) cycles is well above anything demonstrated, this lower value was selected as the design point for the present work. The valve seal must remain leak-tight throughout operation, and the body must maintain a low internal leakage at relatively high operating temperatures. The full set of design requirements used for this program are summarized in Table 1. In this work, we describe two pulsed gas valves that have been fabricated to have long lifetime and demonstrate the characteristics listed above. The first is a miniaturized, conventional electromagnet-based valve while the second is a piezoelectric-based valve design. The conventional valve, shown in Fig. 1, is opened by use of a solenoid electromagnetic actuator. When current is applied to the solenoid coil, magnetic forces pull the plunger away from the valve seat, allowing fluid to flow through the valve. Removal of electrical current permits the spring and fluid pressure to seat the plunger, halting the flow of fluid. The valve body is fabricated from 304L corrosion resistant steel (CRES) and while the parts that form the magnetic circuit are fabricated from 430 CRES. This material does not have optimum magnetic properties, but its corrosion resistance permits incorporation into a design without requiring an additional plating process. A viton O-ring compound (Parker V0884-75), selected for its mechanical strength at elevated temperatures, was used for the valve seat seal. The design was based solely on the use of analytical sizing calculations, as opposed to a more rigorous finite element analysis. While this valve is small and relatively lightweight, it does not represent a design that is optimized for mass and/or a given volume envelope. The piezoelectric valve is a "puller" valve design. Applying a voltage to the piezo crystal causes it to elongate and pull a pintle off the seat, opening the valve. The valve seal consists of the pintle with an external, spherically-formed tip fabricated from

  7. Long-term results of mechanical and biological heart valves in dialysis and non-dialysis patients.

    Science.gov (United States)

    Böning, A; Boedeker, R H; Rosendahl, U P; Niemann, B; Haberer, S; Roth, P; Ennker, J A C

    2011-12-01

    We wanted to answer the question whether biological heart valves are inferior compared to mechanical heart valves in end-stage renal disease (ESRD) patients. Between 01/1996 und 12/2006, 44 of 3293 patients undergoing aortic valve replacement (AVR) in a single institution suffered from dialysis-dependent ESRD and underwent a follow-up investigation after 1.9 years (median). Twelve (28.9 %) of these patients received a biological, 32 (71.1 %) of these patients a mechanical aortic valve prosthesis. To evaluate a possible influence of the valve type (biological/mechanical) on survival, uni- and multivariate logistic regression was used. ESRD patients after AVR had a relatively poor short-term (30-day mortality: 22.7 %) and long-term survival (median survival time: 24.7 months; 95 % CI: 0.2-47.7 months), irrespective of the type of heart valve prosthesis (hazard ratio for mortality depending on heart valve type in dialysis patients: 1.31, P = 0.400). Dialysis-dependent patients were not reoperated due to valve-related reasons. The long-term survival of dialysis-dependent patients after AVR is low (5-year survival: 29.5 %) irrespective of the type of heart valve prosthesis. Therefore, the use of biological AVR is not contraindicated in this group of patients. © Georg Thieme Verlag KG Stuttgart · New York.

  8. A 3D velocimetry study of the flow through prosthetic heart valves

    Science.gov (United States)

    Ledesma, R.; Zenit, R.; Pulos, G.; Sanchez, E.; Juarez, A.

    2006-11-01

    Blood damage commonly appears in medical valve prothesis. It is a mayor concern for the designers and surgeons. It is well known that this damage and other complications result from the modified fluid dynamics through the replacement valve. To evaluate the performance of prosthetic heart valves, it is necessary to study the flow through them. To conduct this study , we have built a flow channel that emulates cardiac conditions and allows optical access such that a 3D-PIV velocimetry system could be used. The experiments are aimed to reconstruct the downstream structure of the flow through a mechanical and a bio-material tricuspid heart valve prothesis. Preliminary results show that the observed coherent structures can be related with haemolysis and trombosis, illnesses commonly found in valve prothesis recipients. The mean flow, the levels of strain rate and the turbulence intensity generated by the valves can also be directly related to blood damage. In general, bio-material made valves tend to reduce these complications.

  9. 3D Printed Multimaterial Microfluidic Valve.

    Directory of Open Access Journals (Sweden)

    Steven J Keating

    Full Text Available We present a novel 3D printed multimaterial microfluidic proportional valve. The microfluidic valve is a fundamental primitive that enables the development of programmable, automated devices for controlling fluids in a precise manner. We discuss valve characterization results, as well as exploratory design variations in channel width, membrane thickness, and membrane stiffness. Compared to previous single material 3D printed valves that are stiff, these printed valves constrain fluidic deformation spatially, through combinations of stiff and flexible materials, to enable intricate geometries in an actuated, functionally graded device. Research presented marks a shift towards 3D printing multi-property programmable fluidic devices in a single step, in which integrated multimaterial valves can be used to control complex fluidic reactions for a variety of applications, including DNA assembly and analysis, continuous sampling and sensing, and soft robotics.

  10. 3D Printed Multimaterial Microfluidic Valve.

    Science.gov (United States)

    Keating, Steven J; Gariboldi, Maria Isabella; Patrick, William G; Sharma, Sunanda; Kong, David S; Oxman, Neri

    2016-01-01

    We present a novel 3D printed multimaterial microfluidic proportional valve. The microfluidic valve is a fundamental primitive that enables the development of programmable, automated devices for controlling fluids in a precise manner. We discuss valve characterization results, as well as exploratory design variations in channel width, membrane thickness, and membrane stiffness. Compared to previous single material 3D printed valves that are stiff, these printed valves constrain fluidic deformation spatially, through combinations of stiff and flexible materials, to enable intricate geometries in an actuated, functionally graded device. Research presented marks a shift towards 3D printing multi-property programmable fluidic devices in a single step, in which integrated multimaterial valves can be used to control complex fluidic reactions for a variety of applications, including DNA assembly and analysis, continuous sampling and sensing, and soft robotics.

  11. Two-Year Outcomes in Patients With Severe Aortic Valve Stenosis Randomized to Transcatheter Versus Surgical Aortic Valve Replacement

    DEFF Research Database (Denmark)

    Søndergaard, Lars; Steinbrüchel, Daniel Andreas; Ihlemann, Nikolaj

    2016-01-01

    BACKGROUND: The Nordic Aortic Valve Intervention (NOTION) trial was the first to randomize all-comers with severe native aortic valve stenosis to either transcatheter aortic valve replacement (TAVR) with the CoreValve self-expanding bioprosthesis or surgical aortic valve replacement (SAVR), inclu...... population. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01057173....

  12. Simplified surgical-hybrid Melody® valve implantation for paediatric mitral valve disease

    OpenAIRE

    Hofmann, Michael; Dave, Hitendu; Hübler, Michael; Kretschmar, Oliver

    2017-01-01

    Children suffering from left atrioventricular valve (LAVV) disease not amenable to repair represent a significant challenge. The results of surgical reconstruction are not optimal. Valve replacement as an alternative is associated with poor results. The surgical-hybrid approach with implantation of a stented biological valve (bovine jugular vein graft, Melody® valve) seems to represent a new therapeutic option. Here we demonstrate our case, the consideration and the approach to extreme clinic...

  13. Propellant actuated nuclear reactor steam depressurization valve

    Science.gov (United States)

    Ehrke, Alan C.; Knepp, John B.; Skoda, George I.

    1992-01-01

    A nuclear fission reactor combined with a propellant actuated depressurization and/or water injection valve is disclosed. The depressurization valve releases pressure from a water cooled, steam producing nuclear reactor when required to insure the safety of the reactor. Depressurization of the reactor pressure vessel enables gravity feeding of supplementary coolant water through the water injection valve to the reactor pressure vessel to prevent damage to the fuel core.

  14. Transapical JenaValve in a patient with mechanical mitral valve prosthesis.

    LENUS (Irish Health Repository)

    O' Sullivan, Katie E

    2014-01-29

    We report the first case of transcatheter aortic valve replacement implantation using JenaValve™ in a patient with mechanical mitral valve prosthesis. We believe that the design features of this valve may be particularly suited for use in this setting. © 2014 Wiley Periodicals, Inc.

  15. Outcome of pregnancy in women after pulmonary autograft valve replacement for congenital aortic valve disease.

    NARCIS (Netherlands)

    Yap, S.C.; Drenthen, W.; Pieper, P.G.; Moons, P.; Mulder, B.J.M.; Klieverik, L.M.; Vliegen, H.W.; Dijk, A.P.J. van; Meijboom, F.J.; Roos-Hesselink, J.W.

    2007-01-01

    BACKGROUND AND AIM OF THE STUDY: The pulmonary autograft has been recommended as the valve of choice for aortic valve replacement (AVR) in young women contemplating pregnancy. However, current information on maternal and perinatal outcome of pregnancy in women with pulmonary autograft valve

  16. Outcome of pregnancy in women after pulmonary autograft valve replacement for congenital aortic valve disease

    NARCIS (Netherlands)

    Yap, Sing-Chien; Drenthen, Willem; Pieper, Petronella G.; Moons, Philip; Mulder, Barbara J. M.; Klieverik, Loes M.; Vliegen, Hubert W.; van Dijk, Arie P. J.; Meijboom, Folkert J.; Roos-Hesselink, Jolien W.

    Background and aim of the study: The pulmonary autograft has been recommended as the valve of choice for aortic valve replacement (AVR) in young women contemplating pregnancy. However, current information on maternal and perinatal outcome of pregnancy in women with pulmonary autograft valve

  17. Successful salvage treatment of native valve Enterococcus faecalis infective endocarditis with telavancin: two case reports.

    Science.gov (United States)

    Thompson, Mickala M; Hassoun, Ali

    2017-07-01

    Infective endocarditis (IE) one-year mortality rates approach 40%. Here, we report two native valve Enterococcus faecalis IE cases in patients successfully treated with telavancin. An 88-year-old with mitral valve endocarditis and a penicillin allergy, initially treated with intravenous vancomycin, was switched to telavancin. A 69-year-old, who previously received amoxicillin and intravenous vancomycin for presumed enterococcal bacteraemia, was diagnosed with dual valve endocarditis for which he received telavancin. Both received six weeks of telavancin. Neither had telavancin-related adverse events, evidence of infection at six months, nor required telavancin dosing adjustments. Documented use of novel treatments for serious enterococcal infections is needed.

  18. Stentless aortic valve replacement: an update

    Directory of Open Access Journals (Sweden)

    Kobayashi J

    2011-06-01

    Full Text Available Junjiro KobayashiDepartment of Cardiovascular Surgery, National Cerebral and Cardiovascular Center, Osaka, JapanAbstract: Although porcine aortic valves or pericardial tissue mounted on a stent have made implantation techniques easier, these valves sacrifice orifice area and increase stress at the attachment of the stent, which causes primary tissue failure. Optimizing hemodynamics to prevent patient–prosthetic mismatch and improve durability, stentless bioprostheses use was revived in the early 1990s. The purpose of this review is to provide a current overview of stentless valves in the aortic position. Retrospective and prospective randomized controlled studies showed similar operative mortality and morbidity in stented and stentless aortic valve replacement (AVR, though stentless AVR required longer cross-clamp and cardiopulmonary bypass time. Several cohort studies showed improved survival after stentless AVR, probably due to better hemodynamic performance and earlier left ventricular (LV mass regression compared with stented AVR. However, there was a bias of operation age and nonrandomization. A randomized trial supported an improved 8-year survival of patients with the Freestyle or Toronto valves compared with Carpentier–Edwards porcine valves. On the contrary, another randomized study did not show improved clinical outcomes up to 12 years. Freedom from reoperation at 12 years in Toronto stentless porcine valves ranged from 69% to 75%, which is much lower than for Carpentier–Edwards Perimount valves. Cusp tear with consequent aortic regurgitation was the most common cause of structural valve deterioration. Cryolife O'Brien valves also have shorter durability compared with stent valves. Actuarial freedom from reoperation was 44% at 10 years. Early prosthetic valve failure was also reported in patients who underwent root replacement with Shelhigh stentless composite grafts. There was no level I or IIa evidence of more effective orifice

  19. Pump arrangement Comprising a Savety Valve

    OpenAIRE

    Richter, M.; Kruckow, J.

    2009-01-01

    A pump arrangement comprises a pump (20) having a pump inlet (22) and a pump outlet (24), which are designed to pump a fluid from the pump inlet to the pump outlet, and it further comprises a safety valve (40), which is disposed between the pump outlet (24) and an outlet (48) of the pump arrangement and comprises a valve set (42) and a valve cover (44). The valve seat, the pump outlet, and the pump inlet are structured in a first surface of a first single-piece part (14) of the pump arrangeme...

  20. Fracturing a dysfunctional Edwards Perimount bioprosthetic valve to facilitate percutaneous valve-in-valve placement of SAPIEN 3 valve with modified delivery system.

    Science.gov (United States)

    Shahanavaz, Shabana; Rockefeller, Toby; Nicolas, Ramzi; Balzer, David

    2017-10-10

    Pulmonary valve replacement via surgical implantation of a bioprosthetic valve (BPV) is a well-established treatment for patients with dysfunctional RV outflow tracts. BPVs are prone to structural deterioration, and will eventually require replacement. Recently, percutaneous valve-in-valve (VIV) placement of transcatheter valves has established itself as a safe and effective alternative to surgical revision. Unfortunately, VIV therapy is inherently limited by the inner diameter of the BPV, which restricts the number of eligible patients. Other centers have reported on the feasibility of cracking certain BPVs with ultra high-pressure balloons in bench testing. We now report cracking an Edwards Perimount BPV in the pulmonary position to facilitate VIV placement of an Edwards SAPIEN 3. The ability to crack the Perimount valve allowed placement of a larger valve than previously considered and minimized the final valve gradient. In an effort to avoid the morbidity and mortality of surgical pulmonary valve replacement, this new strategy will expand the number of patients eligible for percutaneous VIV therapy. © 2017 Wiley Periodicals, Inc.

  1. Aortic Calcification: An Early Sign of Heart Valve Problems?

    Science.gov (United States)

    ... the aortic valve — a condition called aortic valve stenosis. Aortic valve calcification may be an early sign ... have any other heart disease symptoms. Calcification and stenosis generally affects people older than age 65. When ...

  2. 40 CFR 63.175 - Quality improvement program for valves.

    Science.gov (United States)

    2010-07-01

    ... (e.g., ball, gate, check); valve manufacturer; valve design (e.g., external stem or actuating... categories, or classes, of valves as needed to distinguish among operating conditions and services associated...

  3. The mechanobiology of drug-induced cardiac valve disease.

    Science.gov (United States)

    Lam, Ngoc Thien; Balachandran, Kartik

    2015-01-01

    Drug-related adverse reactions leading to valve disease or valvulopathy were first identified in the 1960s. These were associated with patients taking anti-migraine ergot-derivative drugs, anti-anorectics, anti-Parkinson's drugs, or other anti-depressant drugs. In general, these drugs have serotonergic, dopaminergic, or β-adrenergic activity, being either agonists or reuptake inhibitors of the aforementioned neurotransmitter pathways. Recent work has focused on several possible mechanisms for valvulopathy, specifically highlighting the serotonin or 5-hydroxy-trypta-mine-2B (5-HT2B) receptor subtype and the 5-HT transporter as mediators that cause expression of myofibroblast phenotype, excessive cell proliferation, leading to valve fibrosis. Most of these studies and reviews, however, were not reported in the context of the mechanical environment of the valve, which by itself is an important factor in the initiation and progression of valve disease. It is also not known whether patients who have altered mechanical environments in their cardiovascular system, such as those who are hypertensive or have functional cardiac disease, such as ischemic ventricular dilation, or those who have an increased propensity for developing drug-induced valvulopathy. In the present review, we highlight the potential role of hemodynamics and the mechanical environment in influencing these drug-induced valvulopathies, focusing on serotonin-mediated disease and the need for further study of this topic.

  4. Multi-scale biomechanical remodeling in aging and genetic mutant murine mitral valve leaflets: insights into Marfan syndrome.

    Science.gov (United States)

    Gould, Russell A; Sinha, Ravi; Aziz, Hamza; Rouf, Rosanne; Dietz, Harry C; Judge, Daniel P; Butcher, Jonathan

    2012-01-01

    Mitral valve degeneration is a key component of the pathophysiology of Marfan syndrome. The biomechanical consequences of aging and genetic mutation in mitral valves are poorly understood because of limited tools to study this in mouse models. Our aim was to determine the global biomechanical and local cell-matrix deformation relationships in the aging and Marfan related Fbn1 mutated murine mitral valve. To conduct this investigation, a novel stretching apparatus and gripping method was implemented to directly quantify both global tissue biomechanics and local cellular deformation and matrix fiber realignment in murine mitral valves. Excised mitral valve leaflets from wild-type and Fbn1 mutant mice from 2 weeks to 10 months in age were tested in circumferential orientation under continuous laser optical imaging. Mouse mitral valves stiffen with age, correlating with increases in collagen fraction and matrix fiber alignment. Fbn1 mutation resulted in significantly more compliant valves (modulus 1.34 ± 0.12 vs. 2.51 ± 0.31 MPa, respectively, Paging. In comparison, Fbn1 mutated valves have decoupled cellular deformation and fiber alignment with tissue stretch. Taken together, quantitative understanding of multi-scale murine planar tissue biomechanics is essential for establishing consequences of aging and genetic mutations. Decoupling of local cell-matrix deformation kinematics with global tissue stretch may be an important mechanism of normal and pathological biomechanical remodeling in valves.

  5. Living nano-micro fibrous woven fabric/hydrogel composite scaffolds for heart valve engineering.

    Science.gov (United States)

    Wu, Shaohua; Duan, Bin; Qin, Xiaohong; Butcher, Jonathan T

    2017-03-15

    Regeneration and repair of injured or diseased heart valves remains a clinical challenge. Tissue engineering provides a promising treatment approach to facilitate living heart valve repair and regeneration. Three-dimensional (3D) biomimetic scaffolds that possess heterogeneous and anisotropic features that approximate those of native heart valve tissue are beneficial to the successful in vitro development of tissue engineered heart valves (TEHV). Here we report the development and characterization of a novel composite scaffold consisting of nano- and micro-scale fibrous woven fabrics and 3D hydrogels by using textile techniques combined with bioactive hydrogel formation. Embedded nano-micro fibrous scaffolds within hydrogel enhanced mechanical strength and physical structural anisotropy of the composite scaffold (similar to native aortic valve leaflets) and also reduced its compaction. We determined that the composite scaffolds supported the growth of human aortic valve interstitial cells (HAVIC), balanced the remodeling of heart valve ECM against shrinkage, and maintained better physiological fibroblastic phenotype in both normal and diseased HAVIC over single materials. These fabricated composite scaffolds enable the engineering of a living heart valve graft with improved anisotropic structure and tissue biomechanics important for maintaining valve cell phenotypes. Heart valve-related disease is an important clinical problem, with over 300,000 surgical repairs performed annually. Tissue engineering offers a promising strategy for heart valve repair and regeneration. In this study, we developed and tissue engineered living nano-micro fibrous woven fabric/hydrogel composite scaffolds by using textile technique combined with bioactive hydrogel formation. The novelty of our technique is that the composite scaffolds can mimic physical structure anisotropy and the mechanical strength of natural aortic valve leaflet. Moreover, the composite scaffolds prevented the

  6. Coronary artery anomalies and aortic valve morphology in the Syrian hamster.

    Science.gov (United States)

    Fernández, M C; Durán, A C; Real, R; López, D; Fernández, B; de Andrés, A V; Arqué, J M; Gallego, A; Sans-Coma, V

    2000-04-01

    aortic valve from its normal (tricuspid) design. The present findings suggest that in the Syrian hamster, the morphogenetic mechanisms involved in the formation of congenital anomalous aortic valves and anomalies in the origin of the left coronary artery, respectively, are strongly related from an aetiological viewpoint.

  7. Transcatheter heart valve selection and permanent pacemaker implantation in patients with pre-existent right bundle branch block

    NARCIS (Netherlands)

    van Gils, Lennart; Tchetche, Didier; Lhermusier, Thibault; Abawi, Masieh; Dumonteil, Nicolas; Rodriguez Olivares, R; de Nicolas, Javier Molina Martin; Stella, Pieter R.; Carrié, Didier; De Jaegere, Peter P.; Van Mieghem, Nicolas M.

    2017-01-01

    Background-Right bundle branch block is an established predictor for new conduction disturbances and need for a permanent pacemaker (PPM) after transcatheter aortic valve replacement. The aim of the study was to evaluate the absolute rates of transcatheter aortic valve replacement related PPM

  8. Increased nitric oxide release and expression of endothelial and inducible nitric oxide synthases in mildly changed porcine mitral valve leaflets

    DEFF Research Database (Denmark)

    Moesgaard, Sophia Gry; Olsen, Lisbeth Høier; Viuff, Birgitte

    2007-01-01

    NOS) in relation to early local changes in porcine mitral valves. Methods: A histological evaluation of mitral valve leaflets from slaughter pigs and sows was made, and the expression of eNOS and iNOS protein measured using immunohistochemistry. Furthermore, mRNA levels of eNOS and iNOS were measured using real...

  9. Increased nitric oxide release and expression of endothelial and inducible nitric oxide synthases in mildly changed porcine mitral valve leaflets

    DEFF Research Database (Denmark)

    Moesgaard, Sophia G; Olsen, Lisbeth H; Viuff, Birgitte M

    2007-01-01

    NOS) in relation to early local changes in porcine mitral valves. METHODS: A histological evaluation of mitral valve leaflets from slaughter pigs and sows was made, and the expression of eNOS and iNOS protein measured using immunohistochemistry. Furthermore, mRNA levels of eNOS and iNOS were measured using real...

  10. Dynamic Behavior of Reciprocating Plunger Pump Discharge Valve Based on Fluid Structure Interaction and Experimental Analysis.

    Science.gov (United States)

    Wang, Guorong; Zhong, Lin; He, Xia; Lei, Zhongqing; Hu, Gang; Li, Rong; Wang, Yunhai

    2015-01-01

    The influence of spring stiffness and valve quality on the motion behaviors of reciprocating plunger pump discharge valves was investigated by fluid structure interaction (FSI) simulation and experimental analysis. The mathematical model of the discharge valve motion of a 2000-fracturing pump was developed and the discrete differential equations were solved according to FSI and results obtained by ANDINA software. Results indicate that spring stiffness influences the maximum lift, the opening resistance and shut-off lag angle, as well as the fluid velocity of the clearance, the impact stress and the volume efficiency of the pump valve in relation to the valve quality. An optimal spring stiffness parameter of 14.6 N/mm was obtained, and the volumetric efficiency of the pumping valve increased by 4‰ in comparison to results obtained with the original spring stiffness of 10.09N/mm. The experimental results indicated that the mathematical model and FSI method could provide an effective approach for the subsequent improvement of valve reliability, volumetric efficiency and lifespan.

  11. Calcific Aortic Valve Disease Is Associated with Layer-Specific Alterations in Collagen Architecture

    Science.gov (United States)

    Hutson, Heather N.; Marohl, Taylor; Anderson, Matthew; Eliceiri, Kevin; Campagnola, Paul

    2016-01-01

    Disorganization of the valve extracellular matrix (ECM) is a hallmark of calcific aortic valve disease (CAVD). However, while microarchitectural features of the ECM can strongly influence the biological and mechanical behavior of tissues, little is known about the ECM microarchitecture in CAVD. In this work, we apply advanced imaging techniques to quantify spatially heterogeneous changes in collagen microarchitecture in CAVD. Human aortic valves were obtained from individuals between 50 and 75 years old with no evidence of valvular disease (healthy) and individuals who underwent valve replacement surgery due to severe stenosis (diseased). Second Harmonic Generation microscopy and subsequent image quantification revealed layer-specific changes in fiber characteristics in healthy and diseased valves. Specifically, the majority of collagen fiber changes in CAVD were found to occur in the spongiosa, where collagen fiber number increased by over 2-fold, and fiber width and density also significantly increased. Relatively few fibrillar changes occurred in the fibrosa in CAVD, where fibers became significantly shorter, but did not otherwise change in terms of number, width, density, or alignment. Immunohistochemical staining for lysyl oxidase showed localized increased expression in the diseased fibrosa. These findings reveal a more complex picture of valvular collagen enrichment and arrangement in CAVD than has previously been described using traditional analysis methods. Changes in fiber architecture may play a role in regulating the pathobiological events and mechanical properties of valves during CAVD. Additionally, characterization of the ECM microarchitecture can inform the design of fibrous scaffolds for heart valve tissue engineering. PMID:27685946

  12. Regurgitation Hemodynamics Alone Cause Mitral Valve Remodeling Characteristic of Clinical Disease States In Vitro.

    Science.gov (United States)

    Connell, Patrick S; Azimuddin, Anam F; Kim, Seulgi E; Ramirez, Fernando; Jackson, Matthew S; Little, Stephen H; Grande-Allen, K Jane

    2016-04-01

    Mitral valve regurgitation is a challenging clinical condition that is frequent, highly varied, and poorly understood. While the causes of mitral regurgitation are multifactorial, how the hemodynamics of regurgitation impact valve tissue remodeling is an understudied phenomenon. We employed a pseudo-physiological flow loop capable of long-term organ culture to investigate the early progression of remodeling in living mitral valves placed in conditions resembling mitral valve prolapse (MVP) and functional mitral regurgitation (FMR). Valve geometry was altered to mimic the hemodynamics of controls (no changes from native geometry), MVP (5 mm displacement of papillary muscles towards the annulus), and FMR (5 mm apical, 5 mm lateral papillary muscle displacement, 65% larger annular area). Flow measurements ensured moderate regurgitant fraction for regurgitation groups. After 1-week culture, valve tissues underwent mechanical and compositional analysis. MVP conditioned tissues were less stiff, weaker, and had elevated collagen III and glycosaminoglycans. FMR conditioned tissues were stiffer, more brittle, less extensible, and had more collagen synthesis, remodeling, and crosslinking related enzymes and proteoglycans, including decorin, matrix metalloproteinase-1, and lysyl oxidase. These models replicate clinical findings of MVP (myxomatous remodeling) and FMR (fibrotic remodeling), indicating that valve cells remodel extracellular matrix in response to altered mechanical homeostasis resulting from disease hemodynamics.

  13. Current Progress in Tissue Engineering of Heart Valves: Multiscale Problems, Multiscale Solutions

    Science.gov (United States)

    Cheung, Daniel Y; Duan, Bin; Butcher, Jonathan T.

    2016-01-01

    Introduction Heart valve disease is an increasingly prevalent and clinically serious condition. There are no clinically effective biological diagnostics or treatment strategies. The only recourse available is replacement with a prosthetic valve, but the inability of these devices to grow or respond biologically to their environments necessitates multiple resizing surgeries and life-long coagulation treatment, especially in children. Tissue engineering has a unique opportunity to impact heart valve disease by providing a living valve conduit, capable of growth and biological integration. Areas covered This review will cover current tissue engineering strategies in fabricating heart valves and their progress towards the clinic, including molded scaffolds using naturally-derived or synthetic polymers, decellularization, electrospinning, 3D bioprinting, hybrid techniques, and in vivo engineering. Expert opinion While much progress has been made to create functional living heart valves, a clinically viable product is not yet realized. The next leap in engineered living heart valves will require a deeper understanding of how the natural multi-scale structural and biological heterogeneity of the tissue ensures its efficient function. Related, improved fabrication strategies must be developed that can replicate this de novo complexity, which is likely instructive for appropriate cell differentiation and remodeling whether seeded with autologous stem cells in vitro or endogenously recruited cells. PMID:26027436

  14. Calcific Aortic Valve Disease Is Associated with Layer-Specific Alterations in Collagen Architecture.

    Directory of Open Access Journals (Sweden)

    Heather N Hutson

    Full Text Available Disorganization of the valve extracellular matrix (ECM is a hallmark of calcific aortic valve disease (CAVD. However, while microarchitectural features of the ECM can strongly influence the biological and mechanical behavior of tissues, little is known about the ECM microarchitecture in CAVD. In this work, we apply advanced imaging techniques to quantify spatially heterogeneous changes in collagen microarchitecture in CAVD. Human aortic valves were obtained from individuals between 50 and 75 years old with no evidence of valvular disease (healthy and individuals who underwent valve replacement surgery due to severe stenosis (diseased. Second Harmonic Generation microscopy and subsequent image quantification revealed layer-specific changes in fiber characteristics in healthy and diseased valves. Specifically, the majority of collagen fiber changes in CAVD were found to occur in the spongiosa, where collagen fiber number increased by over 2-fold, and fiber width and density also significantly increased. Relatively few fibrillar changes occurred in the fibrosa in CAVD, where fibers became significantly shorter, but did not otherwise change in terms of number, width, density, or alignment. Immunohistochemical staining for lysyl oxidase showed localized increased expression in the diseased fibrosa. These findings reveal a more complex picture of valvular collagen enrichment and arrangement in CAVD than has previously been described using traditional analysis methods. Changes in fiber architecture may play a role in regulating the pathobiological events and mechanical properties of valves during CAVD. Additionally, characterization of the ECM microarchitecture can inform the design of fibrous scaffolds for heart valve tissue engineering.

  15. Resurgery for recurrent heart valve diseases

    Directory of Open Access Journals (Sweden)

    Chong-lei REN

    2017-02-01

    Full Text Available Objective To summarize the experience with resurgery for recurrent valvular heart diseases. Methods From June 2004 to June 2015, 28 patients (15 males and 13 females with ages ranging from 44 to 67 years (55.6±6.5 years with recurrent heart valve disease underwent resurgery. The reasons for resurgery included perivalvular leakage (7 cases, bioprosthetic valve decline (6 cases in mitral valve and 3 in tricuspid valve, mechanical prostheses dysfunction (2cases, infective endocarditis after valve replacement (2 cases, restenosis of repaired native valve (1 case, and severe tricuspid insufficiency after left-side valve surgery (7 cases. Resurgery included mitral valve replacement in 18 patients and tricuspid valve replacement in 10. All the patients underwent third or fourth or even fifth cardiac surgery for valve replacement. Results There were 2 hospital deaths with a mortality of 7.1% (2/28. The main causes of early-stage deaths were low cardiac output syndrome. The main postoperative complications were respiratory failure in 3, low cardiac output syndrome in 2, reexploration for bleeding in 2 and serious infectious shock in 1. All the patients were found with the great improvement in heart function and the re-implanted prostheses worked well during follow-up. Conclusions Although resurgery for recurrent heart valve disease poses a continuing challenge to cardiac surgeon, it could be performed with the satisfactory results. The keys to a successful cardiac resurgery include appropriate operational timing, refined surgical technique and reasonable perioperative managements. DOI: 10.11855/j.issn.0577-7402.2017.01.11

  16. Transcatheter Aortic Valve Replacement Versus Aortic Valve Bypass: A Comparison of Outcomes and Economics.

    Science.gov (United States)

    Brown, John W; Boyd, Jack H; Patel, Parth M; Baker, Mary L; Syed, Amjad; Ladowski, Joe; Corvera, Joel

    2016-01-01

    Transcatheter aortic valve replacement (TAVR) is currently offered to patients who are high-risk candidates for conventional surgical aortic valve replacement. For the past 37 years, off-pump aortic valve bypass (AVB) has been used in elderly patients at our center for this similarly high-risk group. Although TAVR and AVB were offered to similar patients at our center, comparisons of clinical outcomes and hospital economics for each strategy were not reported. We reviewed the clinical and financial records of 53 consecutive AVB procedures performed since 2008 with the records of 51 consecutive TAVR procedures performed since 2012. Data included demographics, hemodynamics, The Society of Thoracic Surgeons (STS) risk score, extent of coronary disease, and ventricular function. Follow-up was 100% in both groups. Hospital financial information for both cohorts was obtained. Mean risk score for the TAVR group was 10.1% versus 17.6% for AVB group (p < 0.001). Kaplan-Meier hospital rates of 3- and 6-month survival and of 1-year survival were 88%, 86%, 81%, and 61% and 89%, 83%, 83%, and 70% for the TAVR and AVB groups, respectively (p = 0.781). Two patients who had undergone TAVR had a procedure-related stroke. The one stroke in an AVB recipient was late and not procedure related. At discharge, mild and moderate perivalvular and central aortic insufficiency were present in 31% and 16% of TAVR recipients, respectively; no AVB valve leaked. Transvalvular gradients were reduced to less than 10 mm Hg in both groups. The average hospital length of stay for the AVB-treated patients was 13 days, and it was 9 days for the TAVR-treated patients. Median hospital charges were $253,000 for TAVR and $158,000 for AVB. Mean payment to the hospital was $65,000 (TAVR) versus $64,000 (AVB), and the mean positive contribution margin (profit) to the hospital was $14,000 for TAVR versus $29,000 for AVB. TAVR and AVB relieve aortic stenosis and have similar and acceptable procedural mortality

  17. Sutureless replacement of aortic valves with St Jude Medical mechanical valve prostheses and Nitinol attachment rings: feasibility in long-term (90-day) pig experiments.

    Science.gov (United States)

    Berreklouw, Eric; Koene, Bart; De Somer, Filip; Bouchez, Stefaan; Chiers, Koen; Taeymans, Yves; Van Nooten, Guido J

    2011-05-01

    Nitinol attachment rings (devices) used to attach mechanical aortic valve prostheses suturelessly were studied in long-term (90 days) pig experiments. The aortic valve was removed and replaced by a device around a St Jude Medical mechanical valve prosthesis in 10 surviving pigs. Supravalvular angiography was done at the end of the operation. No coumarin derivates were given. No or minimal aortic regurgitation was confirmed in all surviving pigs at the end of the operation. Total follow-up was 846 days. In 4 pigs, follow-up was shorter than 90 days (28-75 days); the other 6 pigs did reach 90 days' survival or more. Repeat angiography in 4 pigs at the end of follow-up confirmed the unchanged position of the device at the aortic annulus, without aortic regurgitation. At autopsy, in all pigs the devices proved to be well grown in at the annulus, covered with endothelium, and sometimes tissue overgrowth related to not using coumarin derivates. There was no case of para-device leakage, migration, or embolization. No damage to surrounding anatomic structures or prosthetic valves was found. Nitinol attachment rings can be used to replace the aortic valve suturelessly with St Jude Medical mechanical aortic valve prostheses, without para-device leakage, migration, or damage to the surrounding tissues, in long-term pig experiments during a follow-up of 90 days or more. Refraining from anticoagulation in pigs with mechanical valve prostheses can lead to tissue overgrowth of the valve prosthesis. Further studies are needed to determine long-term feasibility of this method in human beings. Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  18. Robotic mitral valve surgery: a United States multicenter trial.

    Science.gov (United States)

    Nifong, L Wiley; Chitwood, W R; Pappas, P S; Smith, C R; Argenziano, M; Starnes, V A; Shah, P M

    2005-06-01

    In a prospective phase II Food and Drug Administration trial, robotic mitral valve repairs were performed in 112 patients at 10 centers by using the da Vinci surgical system. The safety of performing valve repairs with computerized telemanipulation was studied. After institutional review board approval, informed consent was obtained. Patients had moderate to severe mitral regurgitation. Operative technique included peripheral cardiopulmonary bypass, a 4- to 5-cm right minithoracotomy, a transthoracic aortic crossclamp, and antegrade cardioplegia. The successful study end point was grade 0 or 1 mitral regurgitation by transthoracic echocardiography at 1 month after surgery. Valve repairs included quadrangular resections, sliding plasties, edge-to-edge approximations, and both chordal transfers and replacements. The average age was 56.4 +/- 0.09 years (mean +/- SEM). There were 77 (68.8%) men and 35 (31.2%) women. Valve pathology was myxomatous degeneration in 105 (91.1%), and 103 (92.0%) had type II leaflet prolapse. Leaflet repair times averaged 36.7 +/- 0.2 minutes, with annuloplasty times of 39.6 +/- 0.1 minutes. Total robot, aortic crossclamp, and cardiopulmonary bypass times were 77.9 +/- 0.3 minutes, 2.1 +/- 0.1 hours, and 2.8 +/- 0.1 hours, respectively. On 1-month transthoracic echocardiography, 9 (8.0%) had grade 2 mitral regurgitation, and 6 (5.4%) of these had reoperations (5 replacements and 1 repair). There were no deaths, strokes, or device-related complications. Multiple surgical teams performed robotic mitral valve repairs safely early in development of this procedure, with a reoperation rate of 5.4%. Advancements in robotic design and adjunctive technologies may help in the evolution of this minimally invasive technique by decreasing operative times.

  19. The evolution of minimally invasive valve surgery--2 year experience.

    Science.gov (United States)

    Mohr, F W; Onnasch, J F; Falk, V; Walther, T; Diegeler, A; Krakor, R; Schneider, F; Autschbach, R

    1999-03-01

    The aim of the study was to evaluate the evolution of Port-Access minimally invasive mitral valve surgery to a robot assisted video assisted solo surgery approach. One hundred and twenty-nine patients with non-ischemic mitral valve disease underwent 3D-video assisted mitral valve surgery via a 4 cm right lateral minithoracotomy using femoro-femoral bypass and endoaortic clamping. Transcranial Doppler and continuous transesophageal echocardiography were used to monitor placement and positional stability of the endoclamp. After the initial series (group I, n = 62), a simplified solo surgical technique using voice controlled robotic assistance for videoscope guidance was used in the last 67 patients (group II). After an initial learning curve and modifications of catheter design, the procedure could be steadily redefined and simplified. In the last 67 patients, the procedure was completed without the need for an additional assistant as 'solo surgery'. The mitral valve was repaired in 72 and replaced in all other patients. Duration of bypass and clamp time steadily improved during our study and in the most recent 67 patients average 107 +/- 34 and 48 +/- 16 min, respectively. The voice controlled robotic arm (AESOP 3000, Automated Endoscope System for Optimal Positioning) provided a stable and precise video image with excellent exposure of all valvular and subvalvular structures. Hospital mortality was high in the early series (mean survival 88.7% at 804 +/- 35 days; 95% CI: 735-873) and partially procedure related (aortic dissection in two patients). In group II, hospital mortality has declined to 3.0% (mean survival 97.0% at 568 +/- 12 days; 95% CI: 553-600). Port-Access minimally invasive mitral valve surgery has evolved to be a reliable video assisted technique with reproducible results. Surgery can now be performed almost in the same time as with conventional techniques. Robotic assistance has enabled a solo surgery approach.

  20. Defining indicators to motorize block valves aiming to reduce potential leakage applied to OSBRA pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Pires, L.F.G. [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil); Sousa, A.G.; Castro, N.C.; Spagnolo, R. [Petrobras Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The discussion about motorizing block valves is a constant point being brought up when it is intended to control or reduce the amount of liquid leaking in the event of a pipe rupture. During the pipeline's project stage the installation of blocking valves along the pipeline must be taken into consideration to meet the operation and maintenance requirements as well as to reduce the potential amounts of volume being leaked. In existing pipelines, the main concern is the definition of which valves are candidates to be motorized. In both situations criteria should be established to define this choice. A math algorithm was developed to define the potential leakage due to gravity along the pipeline profile where the influence of a valve over another is verified, as well as the contribution of the check valves existing in the pipeline. The present work defines a parameter based on the extension protected by the valve and the reduction of the potential leakage. This parameter is then fed to a worksheet where the efficiency indicators are calculated to each valve eligible to be motorized. It also takes into consideration factors relative to the valve location, such as the environmental sensitivity, risk assessment, social diagnosis and device's proximity to contingency resources. Finally, after considering all the above aspects, it's possible to come up with a final classification, recommending specific valves to be prioritized on an eventual process of motorization adequacies. This methodology was applied, experimentally on a pipe segment of TRANSPETRO's Sao Paulo-Brasilia pipeline - OSBRA , where it proved to be an important technological and management tool. (author)

  1. Cylinder valve packing nut studies

    Energy Technology Data Exchange (ETDEWEB)

    Blue, S.C. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    The design, manufacture, and use of cylinder valve packing nuts have been studied to improve their resistance to failure from stress corrosion cracking. Stress frozen photoelastic models have been analyzed to measure the stress concentrations at observed points of failure. The load effects induced by assembly torque and thermal expansion of stem packing were observed by strain gaging nuts. The effects of finishing operations and heat treatment were studied by the strain gage hole boring and X-ray methods. Modifications of manufacturing and operation practices are reducing the frequency of stress corrosion failures.

  2. Adaptive Backstepping Control of Nonlinear Hydraulic-Mechanical System Including Valve Dynamics

    Directory of Open Access Journals (Sweden)

    M. Choux

    2010-01-01

    Full Text Available The main contribution of the paper is the development of an adaptive backstepping controller for a nonlinear hydraulic-mechanical system considering valve dynamics. The paper also compares the performance of two variants of an adaptive backstepping tracking controller with a simple PI controller. The results show that the backstepping controller considering valve dynamics achieves significantly better tracking performance than the PI controller, while handling uncertain parameters related to internal leakage, friction, the orifice equation and oil characteristics.

  3. The Heimlich Valve for Pleural Cavity Drainage

    African Journals Online (AJOL)

    The valve drains into a plastic bag that can be held at any level, allowing the patient to be ambulatory by carrying the bag. The construction and function of the valve is easily understood by medical and nursing staff. It is pre sterilized, stored in a sterile package, and readily utilized on emergency vehicles and in the operating.

  4. Numerical Analysis of Large Diameter Butterfly Valve

    Science.gov (United States)

    Youngchul, Park; Xueguan, Song

    In this paper, a butterfly valve with the diameter of 1,800 mm was studied. Three-dimensional numerical technique by using commercial code CFX were conducted to observe the flow patterns and to measure flow coefficient, hydrodynamic torque coefficient and so on, when the large butterfly valve operated with various angles and uniform incoming velocity.

  5. Successful Thrombolysis of Aortic Prosthetic Valve Thrombosis ...

    African Journals Online (AJOL)

    Arun Kumar Agnihotri

    She delivered a normal baby uneventfully in follow up at full term of pregnancy with no complications. Fibrinolytic therapy for mechanical valve thrombosis is a reasonable alternative to surgery in first trimester of pregnancy. KEY WORDS: Prosthetic valve thrombosis; Echocardiography; Streptokinase;. Thrombolysis; Fetus.

  6. High Temperature Resistant Exhaust Valve Spindle

    DEFF Research Database (Denmark)

    Bihlet, Uffe Ditlev

    of the engine, new high temperature alloys are required for a specific engine component, the exhaust valve spindle. Two alloys are used for an exhaust valve spindle; one for the bottom of the spindle, and one for the spindle seat. Being placed in the exhaust gas stream, combustion products such as V2O5 and Na2...

  7. Anatomical challenges for transcatheter mitral valve intervention

    DEFF Research Database (Denmark)

    De Backer, Ole; Luk, Ngai H V; Søndergaard, Lars

    2016-01-01

    , most of these transcatheter mitral valve interventions are still in their early clinical or preclinical development phase. Challenges arising from the complex anatomy of the mitral valve and the interplay of the mitral apparatus with the left ventricle (LV) have contributed to a more difficult...

  8. Anatomical challenges for transcatheter mitral valve intervention

    DEFF Research Database (Denmark)

    De Backer, Ole; Luk, Ngai H V; Søndergaard, Lars

    2016-01-01

    system, most of these transcatheter mitral valve interventions are still in their early clinical or preclinical development phase. Challenges arising from the complex anatomy of the mitral valve and the interplay of the mitral apparatus with the left ventricle (LV) have contributed to a more difficult...

  9. Device at valves. Anordning vid ventiler

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, M.; Hedlund, P.O.

    1990-07-02

    The invention is intended to be utilized in pipes and at valves where there are risks for accumulation of oxyhydrogen gas. In or at the pipe/valve is located a body of recombining material such as platinum or other platinum metals or its alloys in order to recombine oxyhydrogen gas. (L.F.).

  10. AN ACTIVE VALVE WITH A CLAMPED MEMBRANE

    DEFF Research Database (Denmark)

    2009-01-01

    An active valve for use e.g. in fluidic microsystems is provided, wherein the active valve comprises a membrane having at least one flow gate, arranged between a first and a second substantially rigid element. Adjusting means provides an adjustment of the clamping force on membrane arranged between...

  11. Oil pipeline valve automation for spill reduction

    Energy Technology Data Exchange (ETDEWEB)

    Mohitpour, Mo; Trefanenko, Bill [Enbridge Technology Inc, Calgary (Canada); Tolmasquim, Sueli Tiomno; Kossatz, Helmut [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    Liquid pipeline codes generally stipulate placement of block valves along liquid transmission pipelines such as on each side of major river crossings where environmental hazards could cause or are foreseen to potentially cause serious consequences. Codes, however, do not stipulate any requirement for block valve spacing for low vapour pressure petroleum transportation, nor for remote pipeline valve operations to reduce spills. A review of pipeline codes for valve requirement and spill limitation in high consequence areas is thus presented along with a criteria for an acceptable spill volume that could be caused by pipeline leak/full rupture. A technique for deciding economically and technically effective pipeline block valve automation for remote operation to reduce oil spilled and control of hazards is also provided. In this review, industry practice is highlighted and application of the criteria for maximum permissible oil spill and the technique for deciding valve automation thus developed, as applied to ORSUB pipeline is presented. ORSUB is one of the three initially selected pipelines that have been studied. These pipelines represent about 14% of the total length of petroleum transmission lines operated by PETROBRAS Transporte S.A. (TRANSPETRO) in Brazil. Based on the implementation of valve motorization on these three pipeline, motorization of block valves for remote operation on the remaining pipelines is intended, depending on the success of these implementations, on historical records of failure and appropriate ranking. (author)

  12. Heart Valve Disease among Patients with Hyperprolactinaemia

    DEFF Research Database (Denmark)

    Steffensen, Charlotte; Maegbaek, Merete Lund; Laurberg, Peter

    2012-01-01

    Increased risk of heart valve disease during treatment with certain dopamine agonists, such as cabergoline, has been observed in patients with Parkinson's disease. The same compound is used to treat hyperprolactinemia, but it is unknown whether this also associates with heart valve disease....

  13. Mitral valve repair in acquired dextrocardia.

    Science.gov (United States)

    Elmistekawy, Elsayed; Chan, Vincent; Hynes, Mark; Mesana, Thierry

    2015-10-01

    Surgical correction of valvular heart disease in patients with dextrocardia is extremely rare. We report a surgical case of mitral valve repair in a patient with acquired dextrocardia. Successful mitral valve repair was performed through a right lateral thoracotomy. We describe our surgical strategy and summarize the literature. © The Author(s) 2014.

  14. Multidisciplinary optimization of a butterfly valve.

    Science.gov (United States)

    Song, Xue Guan; Wang, Lin; Baek, Seok Heum; Park, Young Chul

    2009-07-01

    A butterfly valve is a type of flow control device, typically used to regulate fluid flow. This paper proposes a new process to meet desired needs in valve design that is characterized by the complex configuration. First, the need is identified according to the valve user/company, and then the problem is defined with a characteristic function. Second, the initial model of valve is made, and then the initial analysis including fluid and/or structural analysis is carried out to predict the fluid and/or structural performance of the valve. Third, the optimization in the form of mathematical functions, which considers single or multiple objective and/or discipline, is handled. This part includes the design of computer experiment, approximation technique, topology optimization and sizing optimization. Finally, the validation experiment is conducted based on the optimum result to verify the accuracy of the optimization. An example is provided to confirm the availability of the process proposed here.

  15. Comments on compressible flow through butterfly valves

    Science.gov (United States)

    Blakenship, John G.

    In the flow analysis of process piping systems, it is desirable to treat control valves in the same way as elbow, reducers, expansions, and other pressure loss elements. In a recently reported research program, the compressible flow characteristics of butterfly valves were investigated. Fisher Controls International, Inc., manufacturer of a wide range of control valves, publishes coefficients that can be used to calculate flow characteristics for the full range of valve movement. The use is described of the manufacturer's data to calculate flow parameters as reported by the researchers who investigated compressible flow through butterfly valves. The manufacturer's data produced consistent results and can be used to predict choked flow and the pressure loss for unchoked flow.

  16. The Leipzig experience with robotic valve surgery.

    Science.gov (United States)

    Autschbach, R; Onnasch, J F; Falk, V; Walther, T; Krüger, M; Schilling, L O; Mohr, F W

    2000-01-01

    The study describes the single-center experience using robot-assisted videoscopic mitral valve surgery and the early results with a remote telemanipulator-assisted approach for mitral valve repair. Out of a series of 230 patients who underwent minimally invasive mitral valve surgery, in 167 patients surgery was performed with the use of robotic assistance. A voice-controlled robotic arm was used for videoscopic guidance in 152 cases. Most recently, a computer-enhanced telemanipulator was used in 15 patients to perform the operation remotely. The mitral valve was repaired in 117 and replaced in all other patients. The voice-controlled robotic arm (AESOP 3000) facilitated videoscopic-assisted mitral valve surgery. The procedure was completed without the need for an additional assistant as "solo surgery." Additional procedures like radiofrequency ablation and tricuspid valve repair were performed in 21 and 4 patients, respectively. Duration of bypass and clamp time was comparable to conventional procedures (107 A 34 and 50 A 16 min, respectively). Hospital mortality was 1.2%. Using the da Vinci telemanipulation system, remote mitral valve repair was successfully performed in 13 of 15 patients. Robotic-assisted less invasive mitral valve surgery has evolved to a reliable technique with reproducible results for primary operations and for reoperations. Robotic assistance has enabled a solo surgery approach. The combination with radiofrequency ablation (Mini Maze) in patients with chronic atrial fibrillation has proven to be beneficial. The use of telemanipulation systems for remote mitral valve surgery is promising, but a number of problems have to be solved before the introduction of a closed chest mitral valve procedure.

  17. Pathogenic Mechanisms of Bicuspid Aortic Valve Aortopathy

    Science.gov (United States)

    Yassine, Noor M.; Shahram, Jasmine T.; Body, Simon C.

    2017-01-01

    Bicuspid aortic valve (BAV) is the most common congenital valvular defect and is associated with ascending aortic dilation (AAD) in a quarter of patients. AAD has been ascribed both to the hemodynamic consequences of normally functioning and abnormal BAV morphology, and to the effect of rare and common genetic variation upon function of the ascending aortic media. AAD manifests in two overall and sometimes overlapping phenotypes: that of aortic root aneurysm, similar to the AAD of Marfan syndrome; and that of tubular AAD, similar to the AAD seen with tricuspid aortic valves (TAVs). These aortic phenotypes appear to be independent of BAV phenotype, have different embryologic origins and have unique etiologic factors, notably, regarding the role of hemodynamic changes inherent to the BAV phenotype. Further, in contrast to Marfan syndrome, the AAD seen with BAV is infrequently present as a strongly inherited syndromic phenotype; rather, it appears to be a less-penetrant, milder phenotype. Both reduced levels of normally functioning transcriptional proteins and structurally abnormal proteins have been observed in aneurysmal aortic media. We provide evidence that aortic root AAD has a stronger genetic etiology, sometimes related to identified common non-coding fibrillin-1 (FBN1) variants and other aortic wall protein variants in patients with BAV. In patients with BAV having tubular AAD, we propose a stronger hemodynamic influence, but with pathology still based on a functional deficit of the aortic media, of genetic or epigenetic etiology. Although it is an attractive hypothesis to ascribe common mechanisms to BAV and AAD, thus far the genetic etiologies of AAD have not been associated to the genetic etiologies of BAV, notably, not including BAV variants in NOTCH1 and GATA4. PMID:28993736

  18. Airbag vent valve and system

    Science.gov (United States)

    Peterson, Leslie D. (Inventor); Zimmermann, Richard E. (Inventor)

    2001-01-01

    An energy absorbing airbag system includes one or more vent valve assemblies for controlling the release of airbag inflation gases to maintain inflation gas pressure within an airbag at a substantially constant pressure during a ride-down of an energy absorbing event. Each vent valve assembly includes a cantilever spring that is flat in an unstressed condition and that has a free end portion. The cantilever spring is secured to an exterior surface of the airbag housing and flexed to cause the second free end portion of the cantilever spring to be pressed, with a preset force, against a vent port or a closure covering the vent port to seal the vent port until inflation gas pressure within the airbag reaches a preselected value determined by the preset force whereupon the free end portion of the cantilever spring is lifted from the vent port by the inflation gases within the airbag to vent the inflation gases from within the airbag. The resilience of the cantilever spring maintains a substantially constant pressure within the airbag during a ride-down portion of an energy absorbing event by causing the cantilever spring to vent gases through the vent port whenever the pressure of the inflation gases reaches the preselected value and by causing the cantilever spring to close the vent port whenever the pressure of the inflation gases falls below the preselected value.

  19. Study on decellularized porcine aortic valve/poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) hybrid heart valve in sheep model.

    Science.gov (United States)

    Wu, Song; Liu, Ying-Long; Cui, Bin; Qu, Xiang-Hua; Chen, Guo-Qiang

    2007-09-01

    To overcome shortcomings of current heart valve prostheses, novel hybrid valves were fabricated from decellularized porcine aortic valves coated with poly (3-hydroxybutyrate-co-3-hydroxyhexanoate [PHBHHx]). In the mechanical test in vitro, the biomechanical performance of hybrid valve was investigated. In an in vivo study, hybrid valve conduits were implanted in pulmonary position in sheep without cardiopulmonary bypass. Uncoated grafts were used as control. The valves were explanted and examined histologically and biochemically 16 weeks after surgery. The hybrid valve conduits maintained original shapes, were covered by a confluent layer of cells, and had less calcification than uncoated control. The mechanical test in vitro revealed that PHBHHx coating improved tensile strength. The results in vivo indicated that PHBHHx coating reduced calcification and promoted the repopulation of hybrid valve with the recipient's cells resembling native valve tissue. The hybrid valve may provide superior valve replacement with current techniques.

  20. The role of the sewing ring in tissue healing: a pathologic study of explanted mechanical heart valves.

    Science.gov (United States)

    Kurian, Mathew V; Sabareeswaran, Arumugam; Kanchanamala, Muniraj; Balachandran, Seetharaman; Mogileswari, Dhananjayan; Subban, Vijayakumar

    2012-03-01

    Serious complications may occur after heart valve replacement, and many such patients will require reoperation. The study aim was to identify the pattern of tissue response around the sewing ring of those valves that have been explanted as a result of various valve-associated complications. A total of 51 mechanical heart valves (MHVs) was explanted from 45 patients who had undergone reoperation for valve-related complications. The examination of the valves included an analysis of the operative findings, macroscopic findings, histopathology, and dissection of the sewing ring. The extent of tissue hyperplasia was variable around the sewing rings of valves explanted for various pathologies. In pannus, the hyperplastic tissue extended into the valve orifice and produced an obstruction to flow, whereas in thrombosed valves the thrombus was attached to the tissue at the annulus. In non-infective pathologies, the histology revealed cellular infiltration that was limited to the peripheral fabric layers of the sewing ring, though the extent of infiltration was not increased with the duration of implantation. In prosthetic valve endocarditis (PVE), the surrounding hyperplastic tissue was granulomatous, but cellular infiltration into the sewing ring was absent. The dissection of various models of explanted valves revealed that different types of filler and fixing mechanisms had increased the bulk of the sewing ring. Tissue hyperplasia of varying extent occurs around the sewing ring after MHV implantation. The cellular elements grow into the peripheral layers, but not the deeper layers, of the sewing ring. In PVE, there was an absence of cellular infiltration into the sewing ring.

  1. A method for evaluating pressure locking and thermal binding of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, T.

    1996-12-01

    A method is described to evaluate the susceptibility of gate valves to pressure locking and thermal binding. Binding of the valve disc in the closed position due to high pressure water trapped in the bonnet cavity (pressure locking) or differential thermal expansion of the disk in the seat (thermal binding) represents a potential mechanism that can prevent safety-related systems from functioning when called upon. The method described here provides a general equation that can be applied to a given gate valve design and set of operating conditions to determine the susceptibility of the valve to fail due to disc binding. The paper is organized into three parts. The first part discusses the physical mechanisms that cause disc binding. The second part describes the mathematical equations. The third part discusses the conclusions.

  2. Cost-utility analysis of cardiac rehabilitation after conventional heart valve surgery versus usual care

    DEFF Research Database (Denmark)

    Hansen, Tina Birgitte; Zwisler, Ann Dorthe; Kikkenborg Berg, Selina

    2017-01-01

    Background While cardiac rehabilitation in patients with ischaemic heart disease and heart failure is considered cost-effective, this evidence may not be transferable to heart valve surgery patients. The aim of this study was to investigate the cost-effectiveness of cardiac rehabilitation following...... heart valve surgery. Design We conducted a cost-utility analysis based on a randomised controlled trial of 147 patients who had undergone heart valve surgery and were followed for 6 months. Methods Patients were randomised to cardiac rehabilitation consisting of 12 weeks of physical exercise training...... rehabilitation compared to usual care is at minimum 75%, driven by a tendency towards costs savings. Conclusions Cardiac rehabilitation after heart valve surgery may not have improved health-related quality of life in this study, but is likely to be cost-effective for society, outweighing the extra costs...

  3. Outcome of bioprosthetic valve replacement in dogs with tricuspid valve dysplasia.

    Science.gov (United States)

    Bristow, P; Sargent, J; Luis Fuentes, V; Brockman, D

    2017-04-01

    To describe the short-term and long-term outcome in dogs with tricuspid valve dysplasia undergoing tricuspid valve replacement under cardiopulmonary bypass. Data were collected from the hospital records of all dogs that had undergone tricuspid valve replacement under cardiopulmonary bypass between 2006 and 2012. Dogs were considered candidates for tricuspid valve replacement if they had severe tricuspid valve regurgitation associated with clinical signs of cardiac compromise. Nine dogs of six different breeds were presented. Median age was 13 months (range 7 to 61 months), median weight 26·5 kg (range 9·7 to 59 kg). Eight bovine pericardial valves and one porcine aortic valve were used. One non-fatal intraoperative complication occurred. Complications during hospitalisation occurred in six dogs, four of which were fatal. Of the five dogs discharged, one presented dead due to haemothorax after minor trauma seven days later. The four remaining dogs survived a median of 533 days; all of these dogs received a bovine pericardial valve. Based on our results, tricuspid valve replacement with bovine or porcine prosthetic valves is associated with a high incidence of complications. © 2017 British Small Animal Veterinary Association.

  4. Quadruple valve replacement with mechanical valves: an 11-year follow-up study.

    Science.gov (United States)

    Cao, Yukun; Gu, Chunhu; Sun, Guocheng; Yu, Shiqiang; Wang, Hongbing; Yi, Dinghua

    2012-06-01

    We performed the first quadruple valve replacement with mechanical valves, combined with the correction of complex congenital heart disease on November 17, 1999. We report here the 11-year follow-up study. A 47-year-old man with subacute rheumatic endocarditis, a ventricular septal defect, and an obstruction of the right ventricular outflow tract required replacement of the aortic, mitral, tricuspid, and pulmonary valves; repair of the ventricular septal defect; and relief of the obstruction of the right ventricular outflow tract. The surgery was done on November 17, 1999, after careful systemic preparation of the patient. Warfarin therapy with a target international normalized ratio (INR) range of 1.5 to 2.0 was used. Follow-up included monitoring the INR, recording the incidences of thromboembolic and bleeding events, electrocardiography, radiography, and echocardiography evaluations. The patient's INR was maintained between 1.5 and 2.0. All 4 mechanical prosthetic heart valves worked well. He is in generally good health without any thromboembolic or bleeding complications. Long-term management is challenging for patients who have experienced quadruple valve replacement with mechanical valves; however, promising results could mean that replacement of all 4 heart valves in 1 operation is feasible in patients with quadruple valve disease, and an INR of 1.5 to 2.0 could be appropriate for Chinese patients with undergoing valve replacement with mechanical valves.

  5. THE RESULTS OF SURGICAL TREATMENT OF TRICUSPID VALVE INFECTIVE ENDOCARDITIS USING VALVE REPAIR AND VALVE REPLACEMENT OPERATIONS

    Directory of Open Access Journals (Sweden)

    S. A. Kovalev

    2015-01-01

    Full Text Available Aim. To evaluate in-hospital and long-term results of surgical treatment of patients with infective endocarditis of the tricuspid valve, to compare the effectiveness of valve repair and valve replacement techniques, and to identify risk factors of mortality and reoperations. Materials and methods. 31 surgical patients with tricuspid valve infective endocarditis were evaluated. Patients were divided into 2 groups. In Group 1 (n = 14 repairs of the tricuspid valve were performed, in Group 2 (n = 17 patients had undergone tricuspid valve replacements. Epidemiological, clinical, microbiological and echocardiographic data were studied. Methods of comparative analysis, the Kaplan–Meier method, and Cox risk models were applied. Results. The most common complication of in-hospital stay was atrioventricular block (17.7% of cases in Group 2. In Group 1, this type of complication was not found. Hospital mortality was 7.14% in Group 1, and 0% in Group 2. Long-term results have shown the significant reduction of heart failure in general cohort and in both groups. In Group 1 the severity of heart failure in the long term was less than in Group 2. No significant differences in the severity of tricuspid regurgitation were found between the groups. In 7-year follow up no cases of death were registered in Group 1. Cumulative survival rate in Group 2 within 60 months was 67.3 ± 16.2%. No reoperations were performed in patients from Group 1. In Group 2, the freedom from reoperation within 60 months was 70.9 ± 15.3%. Combined intervention was found as predictor of postoperative mortality. Prosthetic valve endocarditis was identified as risk factor for reoperation. Conclusion. Valve repair and valve replacement techniques of surgical treatment of tricuspid valve endocarditis can provide satisfactory hospital and long-term results. Tricuspid valve repair techniques allowed reducing the incidence of postoperative atrioventricular block. In the long-term, patients

  6. [Balloon valvuloplasty for congenital aortic valve stenosis in children].

    Science.gov (United States)

    Wu, Lin; Qi, Chunhua; He, Lan; Liu, Fang; Lu, Ying; Huang, Guoying

    2014-09-01

    To evaluate the efficacy and safety of percutaneous balloon aortic valvuloplasty (PBAV) for congenital aortic valve stenosis in children. This is a retrospective clinical study including 14 children treated with PBAV for congenital aortic valve stenosis from October 2006 to December 2012 in our institute. During clinical follow-up, aortic residual stenosis and restenosis, left ventricular function and the procedure-related complications, including the approach artery injury, and aortic regurgitation were particularly assessed. A total of 14 patients consisting of 12 boys and 2 girls underwent the procedure, with mean age (17.1 ± 10.5) months (range from 8 days to 6 years) and the mean body weight (8.9 ± 5.5) kg (range from 1.9 kg to 23.0 kg). The indication for PBAV was a Doppler-derived peak instaneous gradient of ≥ 75 mmHg(1 mmHg = 0.133 kPa) or a smaller gradient with signs of severe left ventricular dysfunction or left ventricular strain on the ECG. The mean ratio of balloon-annulus was 0.92 ± 0.09 (range from 0.75 to 1.09). The catheter-measured peak systolic valve gradient was successfully relieved in all the patients, decreasing from (69 ± 26) mmHg to (29 ± 13) mmHg immediately after balloon valvuloplasty (t = 7.628, P = 0.000). The Doppler-derived peak and mean gradient decreased from (95 ± 21) mmHg and (50 ± 7) mmHg to (49 ± 16) mmHg and (24 ± 11) mmHg, respectively (t = 7.630, 10.401; P = 0.000, 0.000) . The mean follow-up period was 1 day to 61 months. At follow-up, 2 patients (2/14, 14%) underwent the second balloon valvuloplasty for the significant restenosis, and both showed successful relief of restenosis, however 1 patient required surgical Ross procedure due to significant recurrent systolic pressure gradient and moderate aortic regurgitation 4 years after the second balloon valvuloplasty. Among the 3 young infants who presented with congestive heart failure before intervention, 1 died 1 day after the procedure, the other 2 patients had

  7. 49 CFR 192.193 - Valve installation in plastic pipe.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valve installation in plastic pipe. 192.193... Components § 192.193 Valve installation in plastic pipe. Each valve installed in plastic pipe must be designed so as to protect the plastic material against excessive torsional or shearing loads when the valve...

  8. Towards new therapies for calcific aortic valve disease

    NARCIS (Netherlands)

    Riem Vis, P.W.

    2011-01-01

    Calcific aortic valve disease (CAVD) is characterized by progressive calcification of the aortic valve cusps. The end-stage (stenosis), can lead to heart failure and death. Approximately 2-3% of adults over 65 years of age are thought to suffer from valve stenosis, requiring aortic valve

  9. 46 CFR 56.20-9 - Valve construction.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Valve construction. 56.20-9 Section 56.20-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Valves § 56.20-9 Valve construction. (a) Each valve must close with a right-hand (clockwise...

  10. [Clinical analysis of robotic mitral valve repair].

    Science.gov (United States)

    Gao, Chang-Qing; Yang, Ming; Xiao, Cang-Song; Wang, Gang; Wang, Jia-Li; Wu, Yang; Wang, Yao

    2011-07-01

    To determine the safety and efficacy of robotic mitral valve repair using da Vinci S Surgical system. Method From January 2007 to April 2011, over 400 cases of robotic cardiac surgery have been performed, in which 60 patients with isolated mitral valve insufficiency underwent robotic mitral valve repair, including 42 male and 18 female patients with a mean age of (44 ± 13) years (ranging from 14 to 70 years). Forty-eight patients were in NYHA class I-II and 12 patients in class III. Fourteen patients were concomitant with atrial fibrillation. Surgery approach was achieved through 4 right chest ports with femoral perfusion and Chitwood aortic occlusion. Antegrade cold blood cardioplegia was administered directly via chest for myocardial protection. The transesophageal echocardiography was used intraoperatively to estimate the surgical results. All patients had successful valve repair including quadrangular resections, sliding plasties and chordal replacement. There was no conversion to median sternotomy. The mean cardiopulmonary bypass and arrested heart time were (132 ± 30) min and (88 ± 22) min. One patient had hemolysis after operation, and required mitral valve replacement. Echocardiographic follow-up revealed trace to mild regurgitation in 2 patients with a mean of (16 ± 9) months. Robotic mitral valve repair is safe and efficacious in the patients with isolated mitral valve insufficiency.

  11. Motor operated valves problems tests and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pinier, D.; Haas, J.L.

    1996-12-01

    An analysis of the two refusals of operation of the EAS recirculation shutoff valves enabled two distinct problems to be identified on the motorized valves: the calculation methods for the operating torques of valves in use in the power plants are not conservative enough, which results in the misadjustement of the torque limiters installed on their motorizations, the second problem concerns the pressure locking phenomenon: a number of valves may entrap a pressure exceeding the in-line pressure between the disks, which may cause a jamming of the valve. EDF has made the following approach to settle the first problem: determination of the friction coefficients and the efficiency of the valve and its actuator through general and specific tests and models, definition of a new calculation method. In order to solve the second problem, EDF has made the following operations: identification of the valves whose technology enables the pressure to be entrapped: the tests and numerical simulations carried out in the Research and Development Division confirm the possibility of a {open_quotes}boiler{close_quotes} effect: determination of the necessary modifications: development and testing of anti-boiler effect systems.

  12. Percutaneous management of prosthetic valve thrombosis.

    Science.gov (United States)

    Hariram, Vuppaladadhiam

    2014-01-01

    Thrombosis of a prosthetic valve is a serious complication in patients with prosthetic heart valves. Thrombolysis is the initial choice of treatment. Patients who do not respond to thrombolysis are subjected to surgery which carries a high risk. We report a case series of 5 patients with prosthetic mitral valve thrombosis who did not respond to thrombolysis and were subjected to percutaneous manipulation of the prosthetic valves successfully and improved. Five patients who were diagnosed to have prosthetic mitral valve thrombosis and failed to respond to a minimum of 36 h of thrombolysis (persistent symptoms with increased gradients, abnormal findings on fluoroscopy),were subjected to percutaneous treatment after receiving proper consent. None of them had a visible thrombus on transthoracic echocardiogram. All patients underwent transseptal puncture following which a 6F JR4 guiding catheter was passed into the left atrium. The valve leaflets were repeatedly hit gently under fluoroscopic guidance till they regained their normal mobility. Mean age was 38.8 years. Average peak and mean gradients prior to the procedure were 38 and 25 and after the procedure were 12 and 6 mm of Hg respectively. All patients had successful recovery of valve motion on fluoroscopy with normalization of gradients and complete resolution of symptoms. None of the patients had any focal neurological deficits, embolic manifestations or bleeding complications. Percutaneous manipulation of prosthetic valves in selected patients with prosthetic valve thrombosis who do not respond to thrombolytic therapy is feasible and can be used as an alternative to surgery. Copyright © 2014 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

  13. Transcatheter Aortic Valve Replacement: A Review Article

    Directory of Open Access Journals (Sweden)

    Juan A Siordia

    2016-06-01

    Full Text Available Transcatheter aortic valve replacement (TAVR is a novel therapeutic intervention for the replacement of severely stenotic aortic valves in high-risk patients for standard surgical procedures. Since the initial PARTNER trial results, use of TAVR has been on the rise each year. New delivery methods and different valves have been developed and modified in order to promote the minimally invasive procedure and reduce common complications, such as stroke. This review article focuses on the current data on the indications, risks, benefits, and future directions of TAVR. Recently, TAVR has been considered as a standard-of-care procedure. While this technique is used frequently in high-risk surgical candidates, studies have been focusing on the application of this method for younger patients with lower surgical risk. Moreover, several studies have proposed promising results regarding the use of valve-in-valve technique or the procedure in which the valve is placed within a previously implemented bioprosthetic valve. However, ischemic strokes and paravalvular leak remain a matter of debate in these surgeries. New methods and devices have been developed to reduce the incidence of post-procedural stroke. While the third generation of TAVR valves (i.e., Edwards Sapien 3 and Medtronic Evolut R addresses the issue of paravalvular leak structurally, results on their efficacy in reducing the risk of paravalvular leak are yet to be obtained. Furthermore, TAVR enters the field of hybrid methods in the treatment of cardiac issues via both surgical and catheter-based approaches. Finally, while TAVR is primarily performed on cases with aortic stenosis, new valves and methods have been proposed regarding the application of this technique in aortic regurgitation, as well as other aortic pathologies. TAVR is a suitable therapeutic approach for the treatment of aortic stenosis in high-risk patients. Considering the promising results in the current patient population

  14. System of monitoring and diagnosis of motor-operated valves using fuzzy logic; Sistema de monitoracao e diagnostico de valvula moto-operada, utilizando logica nebulosa

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, Alvaro Luiz G.; Silva, Aucyone A. da [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Silva, Aucyone A. da; Andrade, Marco Tulio C. de [Sao Paulo Univ., SP (Brazil). Escola Politecnica

    2000-07-01

    The issue about of reliability of components, more specifically motor-operated valves related to safety systems, has became one of the most important factors to be investigated in nuclear power plants. This work has presented a direct application of fuzzy logic in monitoring and diagnosis systems of motor-operated valves used in nuclear power plants safety systems, based on motor signature power analysis during the operation of opening and closure of valve.

  15. Misleading image of mechanical valve leaflet by transesophageal echocardiography.

    Science.gov (United States)

    Orihashi, Kazumasa

    2011-04-01

    Although bileaflet prosthetic valve function is commonly assessed by means of transesophageal echocardiography (TEE) during surgery, the author reports that the leaflet image is not a real image but an artifact. As the depth of the transducer is altered, the leaflet image is gradually skewed in relation to the plane of the prosthetic valve ring. The leaflet-like image consistently overlaps the line that is drawn from the transducer position to the atrial side edge of the leaflet, indicating that this image is caused by reverberations. Three-dimensional TEE shows that the leaflet image is not semilunar but is elongated towards the left ventricle and unusually tilted. As viewed from the ventricular side, the ring image is elongated and forms a cylinder-like image in the left ventricle, and the leaflets appear to be opening and closing at the bottom of this cylinder. Therefore, TEE assessment of leaflets in the open position can be misleading.

  16. Percutaneous mitral valve repair: A new treatment for mitral regurgitation

    Directory of Open Access Journals (Sweden)

    Claire Kelley

    2016-05-01

    Full Text Available Mitral valve disease affects more than 4 million people in the United States. The gold standard of treatment in these patients is surgical repair or replacement of the valve with a prosthesis. The MitraClip (Abbott Vascular, Menlo Park, CA is a new technology, which offers an alternative to open surgical repair or replacement via a minimally invasive route. We present an evidence-based clinical update that provides an overview of this technology as it relates to managing patients with significant mitral regurgitation. This review article is particularly useful to noninterventional cardiologists and interventional cardiologists who will be managing patients with this novel technology in increased volumes over the next decade but who do not perform this procedure.

  17. Computed Flow Through An Artificial Heart Valve

    Science.gov (United States)

    Rogers, Stewart E.; Kwak, Dochan; Kiris, Cetin; Chang, I-Dee

    1994-01-01

    Report discusses computations of blood flow through prosthetic tilting disk valve. Computational procedure developed in simulation used to design better artificial hearts and valves by reducing or eliminating following adverse flow characteristics: large pressure losses, which prevent hearts from working efficiently; separated and secondary flows, which causes clotting; and high turbulent shear stresses, which damages red blood cells. Report reiterates and expands upon part of NASA technical memorandum "Computed Flow Through an Artificial Heart and Valve" (ARC-12983). Also based partly on research described in "Numerical Simulation of Flow Through an Artificial Heart" (ARC-12478).

  18. Sensitivity study of a valve recession model

    OpenAIRE

    Vera-Cardenas, E.E.; Lewis, R; Slatter, T.

    2017-01-01

    The aim of this work was to carry out a sensitivity\\ud analysis of a valve recession model. \\ud For the sensitivity study, the effects of the param\\ud eters on the valve recession mode\\ud l were \\ud investigated, for both, light duty and heavy duty \\ud engines. It was seen that for light duty \\ud engines, the impact component parameters had the gr\\ud eatest effect on valve recession and \\ud for heavy duty engines the sliding wear component p\\ud arameters have an increasing con-\\ud tribution t...

  19. PUMP ARRANGEMENT COMPRISING A SAFETY VALVE ARRANGEMENT

    OpenAIRE

    Richter, Martin; Wackerle, Martin

    2014-01-01

    A pump arrangement comprises a microfluidic pump (20) having a pump inlet (22) and a pump outlet (24), which is configured to pump a fluid from the pump inlet to the pump outlet, wherein the pump inlet (22) and an inlet (46) of the pump arrangement are fluidically connected. The pump arrangement further comprises a safety valve arrangement having first safety valve (40), the first safety valve (40) being arranged between the pump outlet (24) and an outlet (48) of the pump arrangement and comp...

  20. Rotary Valve FY 2016 Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Fitsos, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-07

    The fiscal year started with the Rotary Valve (RV) being reassembled after having crashed in June of 2015. The crash occurred when the RV inner surface contacted the housing. The cause of the crash was never confirmed. No particles were found in the 2.5 thousandths of an inch gap and the filters the helium gas passed through were all clean. There were marks on the bearings that looked like electrostatic discharge as shown below in Figure 1. These marks hadn’t been seen before and there were similar discharge marks on some of the ball bearings. Examples of this were found in a literature search of bearing failures. This leads to a possible cause due to this arcing affecting the rotational accuracy of the bearings driving the RV into the housing.

  1. Conical seat shut off valve

    Science.gov (United States)

    Farner, Bruce R. (Inventor)

    2012-01-01

    A valve includes a housing defining a bore having an inlet and extending along a longitudinal axis. A head is attached to the housing and defines a head passage having an outlet. A piston is disposed within the bore and includes a piston passage extending through the piston along the longitudinal axis. The piston is moveable between a closed position in which a sealing end of the piston abuts a seat of the head to close fluid communication through the piston passage and an open position in which the sealing end of the piston is axially spaced along the longitudinal axis from the seat of the head to permit fluid communication through the piston passage between the inlet and the outlet. The housing defines an equalizing chamber in fluid communication with the head passage for damping movement of the piston.

  2. Valve Corporation: Composing Internal Markets

    Directory of Open Access Journals (Sweden)

    Todd R. Zenger

    2015-07-01

    Full Text Available Discussions of the Valve Corporation are always enlightening. The skeptic wonders how much is rhetoric and recruiting ploy and how much is real. Is there clear evidence that this organizational design actually works – that it is efficient in this setting? While revenues per employee are quite remarkable, cause and effect are unclear. Is “boss-less-ness” the cause of high sales per employee or simply the result of high sales per employee, fueled from earlier success? The same question could be asked of Google’s unusual organizational approach. Is Google’s success the result of its extensive autonomy granted to employees, or is its past success the enabling cause of such autonomy? Such questions, of course, are empirically unanswerable here. I therefore set them aside and assume this organizational specimen is efficient – well-suited to its environment – and proceed with further commentary.

  3. In vitro balloon dilatation of mitral valve stenosis: the importance of subvalvar involvement as a cause of mitral valve insufficiency

    NARCIS (Netherlands)

    Sadee, A. S.; Becker, A. E.

    1991-01-01

    To investigate the mechanism that increases the orifice area of the mitral valve during balloon dilatation 43 surgically excised intact rheumatic mitral valves were studied. The main pathological features were (a) fibrosis of mitral valve leaflets and commissures (10 valves); (b) fibrosis with

  4. 46 CFR 153.361 - Arrangements for removal of valves from venting systems having multiple relief valves.

    Science.gov (United States)

    2010-10-01

    ... having multiple relief valves. 153.361 Section 153.361 Shipping COAST GUARD, DEPARTMENT OF HOMELAND... removal of valves from venting systems having multiple relief valves. A venting system having multiple... arranged so that cargo vapor will not escape through the opening left after a valve has been removed. ...

  5. Transcatheter aortic valve implantation with balloonexpandable valve: early experience from China

    Directory of Open Access Journals (Sweden)

    Qingsheng Lu

    2015-08-01

    Full Text Available Abstract Objective: The aim of the current study was to evaluate the early experience of the application of transcatheter aortic valve implantation with the balloon-expandable system in China. The transcatheter aortic valve implantation technology has been widely used for patients with inoperable severe aortic stenosis in the developed world. The application of transcatheter aortic valve implantation is still in the early stages of testing in China, particularly for the balloon-expandable valve procedure. Methods: This was a retrospective study. All patients undergoing transcatheter aortic valve implantation with balloon-expandable system in our hospital between 2011 and 2014 were included. Edwards SAPIEN XT Transcatheter Heart Valve was used. The improvement of valve and heart function was evaluated as well as 30-day mortality and major complications according to the VARC-2 definition. Results: A total of 10 transcatheter aortic valve implantation procedures with the balloon-expandable system were performed in our hospital, of which 9 were transfemoral and 1 was transapical. The median age was 76 years, and the median STS score and Logistic EuroSCORE (% were 8.9 and 16.2. The implantation was successfully conducted in all patients, only 2 patients had mild paravalvular leak. There was no second valve implantation. Moreover, no 30-day mortality or complications was reported. Following the transcatheter aortic valve implantation procedure, the heart and valve functions had improved significantly. During the follow-up period of 3-34 months, one patient died of lung cancer 13 months after the operation. Conclusion: This early experience has provided preliminary evidence for the safety and efficacy of transcatheter aortic valve implantation procedure with the balloon-expandable system in the developing world with an increasing aging population.

  6. Osteoprotegerin inhibits aortic valve calcification and preserves valve function in hypercholesterolemic mice.

    Directory of Open Access Journals (Sweden)

    Robert M Weiss

    Full Text Available There are no rigorously confirmed effective medical therapies for calcific aortic stenosis. Hypercholesterolemic Ldlr (-/- Apob (100/100 mice develop calcific aortic stenosis and valvular cardiomyopathy in old age. Osteoprotegerin (OPG modulates calcification in bone and blood vessels, but its effect on valve calcification and valve function is not known.To determine the impact of pharmacologic treatment with OPG upon aortic valve calcification and valve function in aortic stenosis-prone hypercholesterolemic Ldlr (-/- Apob (100/100 mice.Young Ldlr (-/- Apob (100/100 mice (age 2 months were fed a Western diet and received exogenous OPG or vehicle (N = 12 each 3 times per week, until age 8 months. After echocardiographic evaluation of valve function, the aortic valve was evaluated histologically. Older Ldlr (-/- Apob (100/100 mice were fed a Western diet beginning at age 2 months. OPG or vehicle (N = 12 each was administered from 6 to 12 months of age, followed by echocardiographic evaluation of valve function, followed by histologic evaluation.In Young Ldlr (-/- Apob (100/100 mice, OPG significantly attenuated osteogenic transformation in the aortic valve, but did not affect lipid accumulation. In Older Ldlr (-/- Apob (100/100 mice, OPG attenuated accumulation of the osteoblast-specific matrix protein osteocalcin by ∼80%, and attenuated aortic valve calcification by ∼ 70%. OPG also attenuated impairment of aortic valve function.OPG attenuates pro-calcific processes in the aortic valve, and protects against impairment of aortic valve function in hypercholesterolemic aortic stenosis-prone Ldlr (-/- Apob (100/100 mice.

  7. Computational Fluid Dynamics Analysis of Butterfly Valve Performance Factors

    OpenAIRE

    Del Toro, Adam

    2012-01-01

    Butterfly valves are commonly used in industrial applications to control the internal flow of both compressible and incompressible fluids. A butterfly valve typically consists of a metal disc formed around a central shaft, which acts as its axis of rotation. As the valve's opening angle is increased from 0 degrees (fully closed) to 90 degrees (fully open), fluid is able to more readily flow past the valve. Characterizing a valve's performance factors, such as pressure drop, hydrodynamic torqu...

  8. The 3 S's of the Sapien balloon expandable valve.

    Science.gov (United States)

    Kornowski, Ran

    2016-09-01

    The Sapien 3 (S3) balloon expandable aortic valve equipped with an outer skirt to minimize paravalvular leakage (PVL) was built upon the predecessor Sapien XT (SXT) valve. There is scant comparative data of transcatheter aortic valve replacement using S3 versus SXT valve. The study shows that S3 valve is associated with reduced PVL rate compared with SXT, which is an important clinical advantage. © 2016 Wiley Periodicals, Inc.

  9. Robotic mitral valve repair for anterior leaflet and bileaflet prolapse.

    Science.gov (United States)

    Rodriguez, Evelio; Nifong, L Wiley; Chu, Michael W A; Wood, William; Vos, Paul W; Chitwood, W Randolph

    2008-02-01

    Centers have expanded indications for robotic mitral valve repairs to include complex pathologic features. We studied our results after robotic mitral valve repair for anterior leaflet or bileaflet prolapse. Data were collected contemporaneously on 289 patients operated on from May 2000 to September 2006. Every patient underwent preoperative transesophageal echocardiography. Follow-up consisted of serial echocardiograms, clinic visits, and phone conversations with patients and their physicians. A total of 66 patients (anterior leaflet, n = 14; and bileaflet, n = 52) were identified. Mean age was 52.6 +/- 7.1 years, and 57 (86%) patients had New York Heart Association functional class II or III symptoms. Cardiopulmonary bypass and cross-clamp times were 171 +/- 52 and 132 +/- 39 minutes, respectively. The 30-day and late mortality rates were 3% (n = 2) for each time point. There were no device-related or perfusion-related complications or sternotomy conversions. Complications included 2 strokes (3%), 2 bleeding reexplorations (3%), and 10 pleural effusions requiring intervention (15%). The length of hospital stay for surviving patients was 5 +/- 3 days, and time to extubation averaged 9.5 +/- 13 hours. A total of 6 (9%) patients required valve reoperation. Mean follow-up was 795 +/- 495 days, and echocardiographic mitral regurgitation (n = 60) was none or trace (n = 35, 58.3%), mild (n = 19, 31.6%), moderate (n = 2, 3.3%), and severe (n = 4, 6.7%). Robotic mitral valve repair for anterior leaflet and bileaflet prolapse is feasible and safe. Outcomes and degree of late mitral regurgitation are similar to series using conventional techniques. Long-term follow-up is required to formally address the efficacy of robotic repair techniques.

  10. Midterm evaluation of biological prosthetic valves in the pulmonary position of grown-up patients.

    Science.gov (United States)

    Vohra, Hunaid A; Whistance, Robert N; Baliulis, Gedrius; Janusauskas, Vilius; Kaarne, Marrkku; Veldtman, Gruschen R; Roman, Kevin; Vettukattil, Joseph J; Gnanapragasam, James; Salmon, Anthony P; Haw, Marcus P

    2012-04-01

    To examine the midterm clinical outcome of pulmonary valve replacement (PVR) with prosthetic valves. We reviewed 37 consecutive patients who underwent PVR with biological prosthetic valves between September 1999 and June 2010. The median age was 22.6 years (range: 6 to 70 years; three children). The primary diagnosis was Tetralogy of Fallot in 20 patients (54%). Valve pathology was regurgitation in 27 patients (72.9%). Cardiac surgery had been previously performed in 35 patients (94.5%). The median size of the prosthesis was 25 mm (range: 21 to 31 mm). The median follow-up was 42 months (range: 1.2 to 129 months). There were no early valve-related deaths. Hospital mortality was 2.7% (n = 1) and no patient required early rereplacement of prosthesis. Two patients required permanent pacemaker insertion. During follow-up, there was no late death, reoperation for structural valve degeneration, or valve thrombosis. Only one patient required repeated operation for endocarditis at 37 months follow-up. The actuarial survival at 5 years was 95.1 ± 3.8%. Overall freedom from reoperation after PVR at 5 years was 93.0 ± 8.6%. At last follow-up, 34 patients (91.8%) were NYHA class I versus 20 patients (54%) preoperatively (p right ventricular function compared with 26 patients (74.2%) preoperatively. PVR with biological prosthetic valves can be performed with good midterm survival, functional status, and haemodynamics. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  11. Long-Term Clinical Outcomes of Silzone Era St. Jude Medical Mechanical Heart Valves.

    Science.gov (United States)

    Brennan, J Matthew; Zhao, Yue; Williams, Judson; O'Brien, Sean; Dokholyan, Rachel; Gammie, James; Edwards, Fred; Loyo-Berrios, Nilsa; Canos, Daniel; Gross, Thomas; Marinac-Dabic, Danica; Peterson, Eric

    2015-01-01

    Since the voluntary recall of St. Jude Medical (SJM) Silzone impregnated heart valves, no large-scale study has examined their long-term outcomes. Using Medicare-linked records from the Society of Thoracic Surgeons Adult Cardiac Surgery Database (1993-2004), the clinical outcomes were evaluated through eight years among those patients who received SJM mechanical heart valves during the Silzone era (March 1998 to December 1999; n = 3,775), relative to those in both the pre-Silzone era (January 1993 to February 1998; n = 13,570) and the post-Silzone era (January 2000 to December 2004; n = 6,882). An inverse probability weighting was used to balance the observed differences in case mix. During the Silzone era, 79% of all implanted mechanical heart valves were manufactured by SJM. By eight years post-implantation, the most common adverse events in this Medicare-linked cohort (median age 71 years) were death (43.5%) and thromboembolism (14.7%), while valve reoperation (1.7%) and endocarditis (1.4%) were less common. Patients treated during the Silzone era experienced a lower associated risk of mortality to eight years than those in both the pre-Silzone era (adjusted hazards ratio (HR) 0.93, 95% confidence interval (CI) 0.88-0.98) and post-Silzone era (adjusted HR 0.92, CI 0.67-0.98), while the adjusted eight-year risks of reoperation, thromboembolism and endocarditis were similar across the three eras for the overall cohort and among both aortic valve and mitral valve patients. Medicare patients who received SJM mechanical heart valves during the Silzone era experienced similar clinical outcomes as those treated before or after the Silzone era. These data do not substantiate continued public health concerns associated with Silzone era valve prostheses among older individuals.

  12. Large scale steam valve test: Performance testing of large butterfly valves and full scale high flowrate steam testing

    Energy Technology Data Exchange (ETDEWEB)

    Meadows, J.B.; Robbins, G.E.; Roselius, D.G. [and others

    1995-05-01

    This report presents the results of the design testing of large (36-inch diameter) butterfly valves under high flow conditions. The two butterfly valves were pneumatically operated air-open, air-shut valves (termed valves 1 and 2). These butterfly valves were redesigned to improve their ability to function under high flow conditions. Concern was raised regarding the ability of the butterfly valves to function as required with high flow-induced torque imposed on the valve discs during high steam flow conditions. High flow testing was required to address the flow-induced torque concerns. The valve testing was done using a heavily instrumented piping system. This test program was called the Large Scale Steam Valve Test (LSSVT). The LSSVT program demonstrated that the redesigned valves operated satisfactorily under high flow conditions.

  13. No evidence of a detrimental effect of cabergoline therapy on cardiac valves in patients with acromegaly.

    Science.gov (United States)

    Maione, Luigi; Garcia, Cyril; Bouchachi, Amir; Kallel, Nozha; Maison, Patrick; Salenave, Sylvie; Young, Jacques; Assayag, Patrick; Chanson, Philippe

    2012-09-01

    The effects of cabergoline on cardiac valves have been extensively studied in Parkinson's disease and hyperprolactinemia but not in acromegaly, a condition at risk of cardiac valve abnormalities. We examined the prevalence and incidence of heart valve disease and regurgitation in a series of patients with acromegaly treated with cabergoline, by comparison with matched patients who had never received this drug. We conducted a cross-sectional and longitudinal study in a single referral center. Forty-two patients who had received cabergoline at a median cumulative dose of 203 mg for a median of 35 months were compared to 46 patients with acromegaly who had never received cabergoline and who were matched for age, sex, and disease duration. A subgroup of patients receiving cabergoline (n = 26) was evaluated longitudinally before and during cabergoline treatment and compared to a group not receiving cabergoline and followed during the same period (n = 26). Two-dimensional and Doppler echocardiographic findings were reviewed by two cardiologists blinded to treatment. Demographic and clinical features were not significantly different between the groups. Compared to acromegalic controls, patients receiving cabergoline did not have a higher prevalence or incidence of valve abnormalities. A slightly higher prevalence of aortic valve regurgitation and remodeling was found in the controls relative to the cabergoline-treated patients (P Cabergoline therapy is not associated with an increased risk of cardiac valve regurgitation or remodeling in acromegalic patients at the doses used in this study.

  14. A Hybrid Double Access for Transcatheter Mitral Valve-In-Valve Implantation.

    Science.gov (United States)

    Pagnotta, Paolo; Mennuni, Marco G; Ferrante, Giuseppe; Ornaghi, Diego; Bragato, Renato; Cappai, Antioco; Presbitero, Patrizia

    2015-06-01

    We present a case of hybrid mitral valve-in valve implantation. The planned transapical approach failed due to the inability to cross the degenerated stenotic mitral bioprosthesis. An alternative strategy was performed: first, an anterograde crossing of mitral stenosis, and then, a guidewire externalization through the apex by using a snare. To our knowledge, this is the first described case of double approach mitral valve-in valve implantation. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  15. In vitro evaluation of the iValve: a novel hands-free speech valve.

    Science.gov (United States)

    van der Houwen, Eduard B; van Kalkeren, Tjouwke A; Burgerhof, Johannes G M; van der Laan, Bernard F A M; Verkerke, Gijsbertus J

    2011-12-01

    We performed in vitro evaluation of a novel, disposable, automatic hands-free tracheostoma speech valve for laryngectomy patients based upon the principle of inhalation. The commercially available automatic speech valves close upon strong exhalation and open again when the pressure drops. This method makes long sentences or pauses difficult. The novel iValve is designed to allow almost natural speech, with mid-sentence pausing and whispering. The inhalation closing flows and exhalation opening pressures of 6 iValve prototype versions at different settings were compared with physiological values. The airflow resistance at inhalation was compared to physiological values and to commercial valve values. The iValve prototypes showed flow and pressure ranges in concordance with the physiological values in the literature. The airflow resistance in the breathing mode was within the physiological airflow resistance range, yet above the values from the two commercial valves. The resistance in the speaking mode was above the physiological airflow resistance range. In vitro tests show that the iValve versions can be selected and adjusted to operate within the physiological range. The airflow resistance in the breathing mode is good. In speaking mode, inhalation should, and can, be decreased. The iValve should offer the patient a more intuitively useable alternative with more dynamic speech. Its low cost allows disposability and wider use.

  16. Full metal jacket: transfemoral aortic valve implantation for regurgitant valve after endovascular aortic repair†.

    Science.gov (United States)

    Tanyeli, Omer; Dereli, Yuksel; Gormus, Niyazi; Duzenli, Mehmet Akif

    2017-07-25

    Transfemoral aortic valve implantation has become an almost routine interventional procedure for severe aortic stenosis in high-risk patients. Over time an increased number of experiences has led to unusual procedures. In this report, we present a successful valve-in-valve transfemoral aortic valve implantation in a patient with aortic regurgitation, who previously had debranching and thoracic endovascular aortic repair operations. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  17. Valve selection handbook engineering fundamentals for selecting the right valve design for every industrial flow application

    CERN Document Server

    Smith, Peter

    2004-01-01

    Valves are the components in a fluid flow or pressure system that regulate either the flow or the pressure of the fluid. They are used extensively in the process industries, especially petrochemical. Though there are only four basic types of valves, there is an enormous number of different kinds of valves within each category, each one used for a specific purpose. No other book on the market analyzes the use, construction, and selection of valves in such a comprehensive manner.-Covers new environmentally-conscious equipment and practices, the most important hot-button issue in the p

  18. On-line valve monitoring at the Ormen Lange gas plant

    Energy Technology Data Exchange (ETDEWEB)

    Greenlees, R.; Hale, S. [Score Atlanta Inc., Kennesaw, Georgia (United States)

    2011-07-01

    The purpose of this presentation is to discuss replacing time and labor intensive nuclear outage activities with on line condition monitoring solutions, primarily the periodic verification of MOV functionality discussed in USNRC Generic Letter 96.05. This regulation requires that MOV age related performance degradations are properly identified and accounted for, causing utilities to have to retest valves periodically for the duration of the plants operating license. AECL designed CANDU reactors have a world class performance and safety record, with typical average annual capacity factors of 90%. The CANDU reactor design has the ability to refuel on line, as a result (a) it can be a challenge scheduling all required valve testing into limited duration outage work windows, (b) at multi unit sites, Unit 0 valves can be difficult to test because they are rarely ever out of service, (c) deuterium-oxide (heavy water) moderator is expensive to manufacture, as a result, effective through valve leakage monitoring is essential. These three factors alone make CANDU sites the most suitable candidates for on line valve monitoring systems. Nuclear industry regulations have been instrumental in the development of 'at the valve' diagnostic systems, but diagnostic testing has not typically been utilized to the same degree in other less regulated industries. However, that trend is changing, and the move toward valve diagnostics and condition monitoring has moved fastest in the offshore oil and gas industry on the Norwegian side of the North Sea. The Ormen Lange plant, located on Nyhamna Island on the west coast of Norway, operated by Shell, is one of the worlds most advanced gas processing plants. A stated maintenance goal for the plant is that 70% of the maintenance budget and spend should be based on the results of on line condition monitoring, utilizing monitoring systems equipped with switch sensing, strain gages, hydraulic and pneumatic pressure transducers and

  19. Low-Mass VOST Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Two low-mass, linear throttling, high-efficiency, leak-proof cryogenic valves of diameters 1/2" and 4" will be built and tested. Based upon cryogenically-proven...

  20. Fluid-solid modeling of lymphatic valves

    Science.gov (United States)

    Caulk, Alexander; Ballard, Matthew; Nepiyushchikh, Zhanna; Dixon, Brandon; Alexeev, Alexander

    2015-11-01

    The lymphatic system performs important physiological functions such as the return of interstitial fluid to the bloodstream to maintain tissue fluid balance, as well as the transport of immune cells in the body. It utilizes contractile lymphatic vessels, which contain valves that open and close to allow flow in only one direction, to directionally pump lymph against a pressure gradient. We develop a fluid-solid model of geometrically representative lymphatic valves. Our model uses a hybrid lattice-Boltzmann lattice spring method to capture fluid-solid interactions with two-way coupling between a viscous fluid and lymphatic valves in a lymphatic vessel. We use this model to investigate the opening and closing of lymphatic valves, and its effect on lymphatic pumping. This helps to broaden our understanding of the fluid dynamics of the lymphatic system.

  1. VOST Flow-Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Two cryogenic flow-control valves of diameters 1/2" and 2" will be built and tested. Based on cryogenically-proven Venturi Off-Set Technology (VOST) they have no...

  2. Modeling study of the ABS relay valve

    Science.gov (United States)

    Lei, Ming; Lin, Min; Guo, Bin; Luo, Zai; Xu, Weidong

    2011-05-01

    The ABS (anti-lock braking system) relay valve is the key component of anti-lock braking system in most commercial vehicles such as trucks, tractor-trailers, etc. In this paper, structure of ABS relay valve and its work theory were analyzed. Then a mathematical model of ABS relay valve, which was investigated by dividing into electronic part, magnetic part, pneumatic part and mechanical part, was set up. The displacement of spools and the response of pressure increasing, holding, releasing of ABS relay valve were simulated and analyzed under conditions of control pressure 500 KPa, braking pressure 600 KPa, atmospheric pressure 100 KPa and air temperature 310 K. Thisarticle provides reliable theory for improving the performance and efficiency of anti-lock braking system of vehicles.

  3. Computed Tomography of Prosthetic Heart Valves

    NARCIS (Netherlands)

    Habets, J.

    2012-01-01

    Prosthetic heart valve (PHV) dysfunction is an infrequent but potentially life-threatening disease with a heterogeneous clinical presentation. Patients with PHV dysfunction clinically can present with symptoms of congestive heart failure (dyspnea, fatigue, edema), fever, angina pectoris, dizziness

  4. VOST Flow-Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A cryogenic flow-control valve based on Venturi-Offset Technology (VOST) will be designed and modeled. VOST provides precise linear flow control within a...

  5. Heart Valve Surgery Recovery and Follow Up

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Heart Valve Surgery Recovery and Follow Up Updated:Sep 14,2016 ... resources from Adam Pick's blog: Traveling Timeline After Heart Surgery 5 Things to Do While Your Heart Mends ( ...

  6. Posterior Urethral Valves with Severe Unilateral Vesicoureteral ...

    African Journals Online (AJOL)

    2004-08-10

    Aug 10, 2004 ... urinary catheter drainage, with no pedal oedema. There ... In patients with posterior urethral valves (PUV), severe unilateral vesicoureteral reflux (VUR) is one ... evaluation of urinary tract infection (UTI), voiding dysfunction, or ...

  7. Automatic balancing valves in distribution networks today

    Energy Technology Data Exchange (ETDEWEB)

    Golestan, F. [Flow Design, Inc., Dallas, TX (United States)

    1996-12-31

    Automatic flow-limiting (self-actuated) valves have been in the heating, ventilating, and air-conditioning (HVAC) market for some time now. Their principle of operation is based on fluid momentum and Bernoulli`s theorem. Basically, they absorb pressure to keep the flow rate constant. The general operation and their flow characteristics are described in the 1992 ASHRAE Handbook--Systems and Equipment, chapter 43 (ASHRAE 1992). The application and interaction of these valves with other system components, when installed in hydronic distribution networks, are outlined in this presentation. A simple, multilevel piping network is analyzed. The network consists of a pump, connecting piping, an automatic temperature control valve (ATC), a coil, and balancing valves.

  8. Novel passive normally closed microfluidic valve

    CSIR Research Space (South Africa)

    Land, K

    2009-09-01

    Full Text Available -8 lithography and replication molding processes. It was successfully implemented, and initial results show the relationship between the applied pressure and flow rate. In addition to being used as a toggle valve, this design also allows...

  9. Minimally Invasive Transcatheter Aortic Valve Replacement (TAVR)

    Medline Plus

    Full Text Available Watch a Broward Health surgeon perform a minimally invasive Transcatheter Aortic Valve Replacement (TAVR) Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. All rights reserved.

  10. Low-Mass VOST Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A cylindrical, low-mass, high-efficiency, leak-proof cryogenic valve will be designed using composites and exotic metals. Based upon cryogenically-proven Venturi...

  11. Minimally Invasive Transcatheter Aortic Valve Replacement (TAVR)

    Medline Plus

    Full Text Available Watch a Broward Health surgeon perform a minimally invasive Transcatheter Aortic Valve Replacement (TAVR) Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. ...

  12. A Hybrid Tissue-Engineered Heart Valve

    National Research Council Canada - National Science Library

    Alavi, S Hamed; Kheradvar, Arash

    2015-01-01

    This study describes the efforts to develop and test the first hybrid tissue-engineered heart valve whose leaflets are composed of an extra-thin superelastic Nitinol mesh tightly enclosed by uniform...

  13. Glovebox pressure relief and check valve

    Energy Technology Data Exchange (ETDEWEB)

    Blaedel, K.L.

    1986-03-17

    This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury.

  14. Basis of valve operator selection for SMART

    Energy Technology Data Exchange (ETDEWEB)

    Kang, H. S.; Lee, D. J.; See, J. K.; Park, C. K.; Choi, B. S

    2000-05-01

    SMART, an integral reactor with enhanced safety and operability, is under development for use of the nuclear energy. The valve operator of SMART system were selected through the data survey and technical review of potential valve fabrication vendors, and it will provide the establishment and optimization of the basic system design of SMART. In order to establish and optimize the basic system design of SMART, the basis of selection for the valve operator type were provided based on the basic design requirements. The basis of valve operator selection for SMART will be used as a basic technical data for the SMART basic and detail design and a fundamental material for the new reactor development in the future.

  15. Successful Thrombolysis of Aortic Prosthetic Valve Thrombosis ...

    African Journals Online (AJOL)

    Arun Kumar Agnihotri

    threatening. Standard surgical treatment using cardiopulmonary bypass carries high maternal and fetal complications. Here we report a case of an antenatal female in first trimester with aortic prosthetic valve thrombosis (PVT), who was successfully ...

  16. Frostless heat pump having thermal expansion valves

    Science.gov (United States)

    Chen, Fang C [Knoxville, TN; Mei, Viung C [Oak Ridge, TN

    2002-10-22

    A heat pump system having an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant and further having a compressor, an interior heat exchanger, an exterior heat exchanger, a heat pump reversing valve, an accumulator, a thermal expansion valve having a remote sensing bulb disposed in heat transferable contact with the refrigerant piping section between said accumulator and said reversing valve, an outdoor temperature sensor, and a first means for heating said remote sensing bulb in response to said outdoor temperature sensor thereby opening said thermal expansion valve to raise suction pressure in order to mitigate defrosting of said exterior heat exchanger wherein said heat pump continues to operate in a heating mode.

  17. Can contrast-enhanced multi-detector computed tomography replace transesophageal echocardiography for the detection of thrombogenic milieu and thrombi in the left atrial appendage. A prospective study with 124 patients; Kann die kontrastmittelverstaerkte Mehrzeilen-Computertomografie die transoesophageale Echokardiografie bei der Detektion von thrombogenem Milieu und Vorhofohrthromben ersetzen? Eine prospektive Studie mit 124 Patienten

    Energy Technology Data Exchange (ETDEWEB)

    Homsi, R.; Luetkens, J.A.; Schild, H.H.; Naehle, C.P. [Bonn Univ. (Germany). Dept. of Radiology; Nath, B. [SHG-KLliniken Voelklingen (Germany). Dept. of Medicine I - Cardiology; Schwab, J.O. [Bonn Univ. (Germany). Dept. of Medicine I - Cardiology

    2016-01-15

    To assess the diagnostic value of contrast-enhanced multi-detector computed tomography (MD-CT) for identifying patients with left atrial appendage (LAA) thrombus or circulatory stasis. 124 patients with a history of atrial fibrillation and/or cerebral ischemia (83 men, mean age 58.6 ± 12.4 years) and with a clinical indication for MD-CT of the heart and for transesophageal echocardiography (TEE) were included in the study. LAA thrombus or thrombogenic milieu was visually identified in TEE and MD-CT. In addition, MD-CT was analyzed quantitatively measuring the Hounsfield units (HU) of the left atrium (LA), the LAA and the ascending aorta (AA), and calculating the HU ratios LAA/AA (HU [LAA/AA]) und LAA/LA (HU [LAA/LA]). Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were calculated. The prevalence of a thrombus or thrombogenic milieu as assessed by TEE was 21.8 %. The HU ratio was lower in patients with thrombus or thrombogenic milieu (HU [LAA/AA]: 0.590 ± 0.248 vs. 0.909 ± 0.141; p < 0.001 und HU [LAA/LA] 0.689 ± 0.366 vs. 1.082 ± 0.228; p < 0.001). For the diagnosis of thrombus or a thrombogenic milieu, visual analysis yielded a sensitivity of 81.5 %, a specificity of 96.9 %, a PPV of 87.5 % and a NPV of 95.2 %. By combining visual and quantitative analysis with one criterion being positive, the specificity decreased to 91.8 %, the sensitivity to 77.8 %, the PPV to 72.4 %, and the NPV to 94.9 %. Visual analysis of the LAA in the evaluation of thrombus or thrombogenic milieu yields a high NPV of 95.1 % and may especially be useful to rule out LAA thrombi in patients with contraindications for TEE. Additional calculation of HU ratios did not improve the diagnostic performance of MD-CT.

  18. Infective endocarditis following transcatheter aortic valve replacement-

    DEFF Research Database (Denmark)

    Loh, Poay Huan; Bundgaard, Henning; S�ndergaard, Lars

    2013-01-01

    Transcatheter aortic valve replacement (TAVR) can improve the symptoms and prognosis of patients with severe aortic stenosis who, due to a high expected operative risk, would not have otherwise been treated surgically. If these patients develop prosthetic valve endocarditis, their presentations m...... treated medically, discuss the challenges in the diagnosis and management of such patients, and review available literature on the incidence and outcome of the condition. © 2012 Wiley Periodicals, Inc....

  19. Numerical simulation of mitral valve function

    OpenAIRE

    Lau, K. D.

    2012-01-01

    In the mammalian heart there are four heart valves (HV), of which the largest is the mitral valve (MV). Key components in the circulatory system, correct HV function is vital to cardiovascular health. A tethered and asymmetric structure, the MV regulates unidirectional flow between the left atrium and left ventricle. MVfunction is divided between systole/closure, where theMVis required to sustain a pressure load ~120 mmHg whilst minimising flow reversal, and diastole/opening in wh...

  20. Native valve Escherichia coli endocarditis following urosepsis

    Directory of Open Access Journals (Sweden)

    D Rangarajan

    2013-01-01

    Full Text Available Gram-negative organisms are a rare cause of infective endocarditis. Escherichia coli, the most common cause of urinary tract infection and gram-negative septicemia involves endocardium rarely. In this case report, we describe infection of native mitral valve by E. coli following septicemia of urinary tract origin in a diabetic male; subsequently, he required prosthetic tissue valve replacement indicated by persistent sepsis and congestive cardiac failure.

  1. Native valve Escherichia coli endocarditis following urosepsis

    OpenAIRE

    Rangarajan, D.; Ramakrishnan, S.; Patro, K. C.; Devaraj, S.; Krishnamurthy, V.; Kothari, Y.; Satyaki, N.

    2013-01-01

    Gram-negative organisms are a rare cause of infective endocarditis. Escherichia coli, the most common cause of urinary tract infection and gram-negative septicemia involves endocardium rarely. In this case report, we describe infection of native mitral valve by E. coli following septicemia of urinary tract origin in a diabetic male; subsequently, he required prosthetic tissue valve replacement indicated by persistent sepsis and congestive cardiac failure.

  2. Potential problems will drillstring safety valves

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-06-01

    In the paper titled ``New generation drill string safety valves,`` presented at the IADC Well Control Conference for Europe, Aberdeen, May 22--24, 1996, documented limitations of presently available drillstring safety valves commonly used as kelly valves and stabbing valves were presented, and industry efforts to develop solutions to these problems were described. Authors of the paper are B.A. Tarr and R.A. Sukup (Mobil E and P Technology Center, Dallas), Dr. R. Luy (ITE, Clausthal, Germany), G. Rabby (Hi-Kalibre, Edmonton, Alberta) and J. Mertsch (ITAG, Celle, Germany). In 1995, the Task Group developed a draft of a new spec, and a DSSV testing program was initiated as a joint industry project, with the Gas Research Institute (GRI) as the major sponsor. Two manufacturers, Hi-Kalibre and ITAG, agreed to build new valves for the testing program. Hi-Kalibre, Edmonton, Alberta, supplied an already-commercial twin floating ball valve for November 1995 testing. This product is being used by Tesco in its portable top drive system. ITAG of Germany supplied a radically improved DSSV design, which was tested in December, and was to be retested in May following modifications.

  3. Europa Propulsion Valve Seat Material Testing

    Science.gov (United States)

    Addona, Brad M.

    2017-01-01

    The Europa mission and spacecraft design presented unique challenges for selection of valve seat materials that met the fluid compatibility requirements, and combined fluid compatibility and high radiation exposure level requirements. The Europa spacecraft pressurization system valves will be exposed to fully saturated propellant vapor for the duration of the mission. The effects of Nitrogen Tetroxide (NTO) and Monomethylhydrazine (MMH) propellant vapors on heritage valve seat materials, such as Vespel SP-1 and Polychlorotrifluoroethylene (PCTFE), were evaluated to determine if an alternate material is required. In liquid system applications, Teflon is the only available compatible valve seat material. Radiation exposure data for Teflon in an air or vacuum environment has been previously documented. Radiation exposure data for Teflon in an oxidizer environment such as NTO, was not available, and it was unknown whether the effects would be similar to those on air-exposed samples. Material testing was conducted by Marshall Space Flight Center (MSFC) and White Sands Test Facility (WSTF) to determine the effects of propellant vapor on heritage seat materials for pressurization valve applications, and the effects of combined radiation and NTO propellant exposure on Teflon. The results indicated that changes in heritage pressurization valve seat materials' properties rendered them unsuitable for the Europa application. The combined radiation and NTO exposure testing of Teflon produced results equivalent to combined radiation and air exposure results.

  4. A Hybrid Tissue-Engineered Heart Valve.

    Science.gov (United States)

    Alavi, S Hamed; Kheradvar, Arash

    2015-06-01

    This study describes the efforts to develop and test the first hybrid tissue-engineered heart valve whose leaflets are composed of an extra-thin superelastic Nitinol mesh tightly enclosed by uniform tissue layers composed of multiple cell types. The trileaflet Nitinol mesh scaffolds underwent three-dimensional cell culture with smooth muscle and fibroblast/myofibroblast cells enclosing the mesh, which were finally covered by an endothelial cell layer. Quantitative and qualitative assays were performed to analyze the microstructure of the tissues. A tissue composition almost similar to that of natural heart valve leaflets was observed. The function of the valves and their Nitinol scaffolds were tested in a heart flow simulator that confirmed the trileaflet valves open and close robustly under physiologic flow conditions with an effective orifice area of 75%. The tissue-metal attachment of the leaflets once exposed to physiologic flow rates was tested and approved. Our preliminary results indicate that the novel hybrid approach with nondegradable scaffold for engineering heart valves is viable and may address the issues associated with current tissue-engineered valves developed with degradable scaffolds. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  5. Experimental study of asymmetric heart valve prototype

    Science.gov (United States)

    Vukicevic, M.; Fortini, S.; Querzoli, G.; Cenedese, A.; Pedrizzetti, G.

    2011-11-01

    The mechanical heart valves (MHVs) are extremely important medical devices, commonly used for diseased heart valves replacement. Despite the long term of use and constant design refinement, the MHVs are very far from ideal and their performance is very diverse from that of the native ones. It has been approved that small variations in geometry of valvular leaflets influence the significant change in the intraventricular vortical flow, known as one of the most important factors for the overall functionality of the heart. We have experimentally examined the home-made heart valve prototypes, exclusively modeled for the mitral valve replacement. The performance and energetic properties of the prototypes have been compared with those in the presence of standard MHVs. The analysis was based on the testing of intraventricular fluid dynamics, usually missing criteria for the quality of the valve performance. It has been shown that the asymmetric prototype, with unequal leaflets and D-shaped orifice produces flow patterns and energetic properties close to those found in the healthy subjects. Thus, the break of symmetry in the standard bi-leaflet MHV prosthesis, at least from the fluid dynamics point of view, is worthwhile to be considered for the design of MHVs for the mitral valve replacement.

  6. Comparison of polypropylene and silicone Ahmed Glaucoma Valves.

    Science.gov (United States)

    Ishida, Kyoko; Netland, Peter A; Costa, Vital P; Shiroma, Lineu; Khan, Baseer; Ahmed, Iqbal Ike K

    2006-08-01

    To evaluate and compare the clinical outcomes after implantation of the silicone plate and the polypropylene plate Ahmed Glaucoma Valves. Prospective, multicenter, comparative series. A total of 132 patients with uncontrolled glaucoma were treated with either the silicone or polypropylene Ahmed Glaucoma Valve implant. Success was defined according to 2 criteria: (1) intraocular pressure (IOP) of 6 mmHg or more or 21 mmHg or less, and (2) IOP reduction of at least 30% relative to preoperative values. Eyes requiring further glaucoma surgery, including cyclophotocoagulation, or showing loss of light perception were classified as failures. Average follow-up was 12.8 months (range, 6-30 months) for the silicone plate group and 14.5 months (range, 6-30 months) for the polypropylene plate group (P = 0.063). At the last follow-up examination, the mean IOP was 13.8+/-3.9 mmHg and 17.3+/-6.5 mmHg (PAhmed Glaucoma Valve (model FP7) showed improved IOP reduction compared with the polypropylene (model S2) implant. Differences observed in mean IOP, success rate, and complications suggest that plate material may influence clinical outcome.

  7. Recent NRC research activities addressing valve and pump issues

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, D.L.

    1996-12-01

    The mission of the U.S. Nuclear Regulatory Commission (NRC) is to ensure the safe design, construction, and operation of commercial nuclear power plants and other facilities in the U.S.A. One of the main roles that the Office of Nuclear Regulatory Research (RES) plays in achieving the NRC mission is to plan, recommend, and implement research programs that address safety and technical issues deemed important by the NRC. The results of the research activities provide the bases for developing NRC positions or decisions on these issues. Also, RES performs confirmatory research for developing the basis to evaluate industry responses and positions on various regulatory requirements. This presentation summarizes some recent RES supported research activities that have addressed safety and technical issues related to valves and pumps. These activities include the efforts on determining valve and motor-operator responses under dynamic loads and pressure locking events, evaluation of monitoring equipment, and methods for detecting and trending aging of check valves and pumps. The role that RES is expected to play in future years to fulfill the NRC mission is also discussed.

  8. Presence of Coxiella burnetii DNA in inflamed bovine cardiac valves.

    Science.gov (United States)

    Agerholm, Jørgen S; Jensen, Tim K; Agger, Jens F; Engelsma, Marc Y; Roest, Hendrik I J

    2017-03-09

    Bacterial endocarditis is a recognised disease in humans and animals. In humans, infection with Coxiella burnetii can cause endocarditis, but this has not been investigated thoroughly in animals. Endocarditis in cattle is a common post-mortem finding in abattoirs and studies have identified Trueperella pyogenes as a major cause. Despite exposure of cattle to C. burnetii, the significance of this particular bacterium for development and progression of endocarditis has not been studied in detail. Cardiac valves of cattle affected with endocarditis (n = 100) were examined by histology, fluorescence in situ hybridization (FISH) and real time quantitative polymerase chain reaction (PCR). Serum was examined for anti-C. burnetii antibodies by enzyme-linked immunosorbent assay (ELISA). Serology revealed that 70% of the cattle were positive for antibodies to C. burnetii, while PCR analysis identified 25% of endocarditis valve samples as being positive. C. burnetii was not detected by FISH, probably due to the low infection levels. Most cattle had chronic valvular vegetative endocarditis with lesions being characterised by a core of fibrous tissue covered by significant amounts of fibrin, sometimes with areas of liquefaction, and with a coagulum covering the surface. In a few cases, including the case with the highest infection level, lesions were characterized by extensive fibrosis and calcification. Histologically, bacteria other than C. burnetii were observed in most cases. The presence of C. burnetii DNA is relatively common in cattle affected with valvular endocarditis. The role of C. burnetii remains however unknown as lesions did not differ between C. burnetii infected and non-infected cattle and because T. pyogenes-like bacteria were present in the inflamed valves; a bacterium able to induce the observed lesions. Heart valves of normal cattle should be investigated to assess if C. burnetii may be present without preexisting lesions.

  9. Hybrid Palliation for Interrupted Aortic Arch With Small Aortic Valve.

    Science.gov (United States)

    Uno, Yoshimasa; Masuoka, Ayumu; Hotoda, Kentarou; Katogi, Toshiyuki; Suzuki, Takaaki

    2017-05-01

    Open heart surgery for interrupted aortic arch in the neonatal period is still a high-risk procedure related in part to patient factors such as low birth weight, other morphologic anomalies, and, especially, small aortic valve size. Recently, we performed hybrid palliation with bilateral pulmonary artery banding and ductal stenting as the first-stage palliation for such cases. In this study, the outcomes of this procedure were examined. Six cases of interrupted aortic arch with a small aortic valve underwent the hybrid procedure in the neonatal period in our institute from 2010 to 2015 (mean age: 6.8 days, mean body weight: 3.2 kg, mean z score of the aortic valve annulus: -8.3). Their postoperative clinical courses and results of the second-stage surgery were evaluated. No mortality or severe morbidity was seen in association with initial hybrid palliation. Five of six patients were discharged from the hospital; the one exception had a significant urinary tract anomaly. None needed an additional catheter intervention or surgical procedure postoperatively. All surviving patients underwent second-stage surgery; three had biventricular repair by the conventional method or Damus-Kaye-Stansel anastomosis with the Rastelli procedure and the other three proceeded toward staged Fontan reconstruction. Growth of the aortic valve was seen in four patients, and increased indexed left ventricle volume was recognized in one after the palliation. Hybrid palliation could be useful not only to avoid high-risk neonatal surgery but also to allow for eventual selection of the second-stage surgery based on the observations of potential interval development of left ventricular structures.

  10. Comparative Matched Outcome of Evolut-R vs CoreValve Transcatheter Aortic Valve Implantation.

    Science.gov (United States)

    Landes, Uri; Bental, Tamir; Barsheshet, Alon; Assali, Abid; Vaknin Assa, Hana; Levi, Amos; Orvin, Katia; Kornowski, Ran

    2017-02-01

    The Evolut-R (Medtronic, Inc) is a transcatheter aortic valve implantation (TAVI) system that was built on the well-established foundation of Medtronic's CoreValve device platform. Although already in extensive clinical utilization, it is unknown if the Evolut-R improves TAVI outcomes. Herein, we compared TAVI outcomes of the Evolut-R and CoreValve devices. A propensity score 1:1 matching was conducted on 358 Evolut-R patients (n = 75) and CoreValve patients (n = 283). Thirty-day outcomes were compared using Valve Academic Research Consortium (VARC)-2 criteria. A combined 30-day endpoint including all-cause death, stroke, major vascular complication, major bleeding, implantation failure, paravalvular leak (PVL) ≥ moderate, and new pacemaker implantation was also tested. The final study group included 146 patients (73 Evolut-R; 73 CoreValve). Post matching, baseline characteristics were similar between the two groups. Mean patient age was 82 ± 6 years, mean STS score was 5.2 ± 3.8, 72% were female, and 17% were deemed frail. Implantation success reached 99% with Evolut-R and 94% with CoreValve (P=.10). Both groups had low periprocedural stroke/myocardial infarction/mortality rates and there was also no difference in 30-day vascular complications (P=.18), bleeding (P=.37), PVL (P=.24), and new pacemaker (P=.14). The combined outcome rate was 24% with Evolut-R and 37% with CoreValve (P=.10). This study indicates that the efficacy and safety of the self-expandable second-generation Evolut-R transcatheter valve is at least comparable with the first-generation CoreValve. The observed improved performance in correct positioning of a single valve and the numerically lower chance to suffer a combined TAVI endpoint needs further investigation.

  11. Conceptual model for early health technology assessment of current and novel heart valve interventions.

    Science.gov (United States)

    Huygens, Simone A; Rutten-van Mölken, Maureen P M H; Bekkers, Jos A; Bogers, Ad J J C; Bouten, Carlijn V C; Chamuleau, Steven A J; de Jaegere, Peter P T; Kappetein, Arie Pieter; Kluin, Jolanda; van Mieghem, Nicolas M D A; Versteegh, Michel I M; Witsenburg, Maarten; Takkenberg, Johanna J M

    2016-01-01

    The future promises many technological advances in the field of heart valve interventions, like tissue-engineered heart valves (TEHV). Prior to introduction in clinical practice, it is essential to perform early health technology assessment. We aim to develop a conceptual model (CM) that can be used to investigate the performance and costs requirements for TEHV to become cost-effective. After scoping the decision problem, a workgroup developed the draft CM based on clinical guidelines. This model was compared with existing models for cost-effectiveness of heart valve interventions, identified by systematic literature search. Next, it was discussed with a Delphi panel of cardiothoracic surgeons, cardiologists and a biomedical scientist (n=10). The CM starts with the valve implantation. If patients survive the intervention, they can remain alive without complications, die from non-valve-related causes or experience a valve-related event. The events are separated in early and late events. After surviving an event, patients can experience another event or die due to non-valve-related causes. Predictors will include age, gender, NYHA class, left ventricular function and diabetes. Costs and quality adjusted life years are to be attached to health conditions to estimate long-term costs and health outcomes. We developed a CM that will serve as foundation of a decision-analytic model that can estimate the potential cost-effectiveness of TEHV in early development stages. This supports developers in deciding about further development of TEHV and identifies promising interventions that may result in faster take-up in clinical practice by clinicians and reimbursement by payers.

  12. Transcatheter aortic valve implantation with the self-expandable venus A-Valve and CoreValve devices: Preliminary Experiences in China.

    Science.gov (United States)

    Liao, Yan-Biao; Zhao, Zhen-Gang; Wei, Xin; Xu, Yuan-Ning; Zuo, Zhi-Liang; Li, Yi-Jian; Zheng, Ming-Xia; Feng, Yuan; Chen, Mao

    2017-03-01

    Transcatheter aortic valve implantation (TAVI) has been demonstrated to be an effective alternative to surgical aortic valve replacement (SAVR) in patients with aortic stenosis who are deemed high risk or inoperable. Currently, TAVI procedures in China mostly make use of the domestic Venus A-Valve and the CoreValve; however, there is no data on their comparative performance. Consecutive patients undergoing TAVI with the aforementioned devices were included. The outcomes were reported according to the Valve Academic Research Consortium-2 (VARC) definitions. A total of 54 TAVI procedures were performed, 27 with the CoreValve and the other 27 with the Venus A-Valve. An additional valve was required in 4 (14.8%) and 3 (11.1%) patients, and the VARC-2 device success rates were 81.5 and 85.2%, respectively. The incidences of common complications were similar, except for the significantly less frequent pacemaker insertion in the Venus A-Valve group (7.4 vs. 37.0%, P = 0.03). Within 30 days, 2 (3.7%) patients died, 1 in each group, and both had a bicuspid aortic valve (BAV). No other serious complications, such as annular rupture, coronary obstruction and aortic dissection, occurred in the 32 BAV patients treated with the Venus A-Valve (14) or the CoreValve (18). After 2-years of follow-up, there was no significant difference between CoreValve group and Venus-A group (11.1 vs. 7.4%, P = 0.64). TAVI with the domestic Venus A-Valve is feasible, safe, and can produce favorable short-term outcomes comparable to those with the CoreValve in inoperable or high-risk patients with tricuspid and bicuspid aortic valve stenosis. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  13. Causes of repair failure for degenerative mitral valve disease and reoperation outcomes.

    Science.gov (United States)

    Nishida, Hidefumi; Fukui, Toshihiro; Kasegawa, Hitoshi; Kin, Hajime; Yamazaki, Masataka; Takanashi, Shuichiro

    2018-01-03

    This study aimed to evaluate the causes of initial mitral valve (MV) repair failure, the details of reoperation and the long-term outcomes of mitral valve re-repair (Re-MVP). We retrospectively reviewed 86 patients who underwent reoperation after MV repair for MR due to degenerative disease from October 1991 to December 2015. First, we analysed the initial MV repair data, causes of MV repair failure, reoperation data and long-term outcomes including survival. Second, the patients were classified into 2 groups based on valve related failure or procedure related failure , and the differences between the groups were analysed. Leaflet prolapse at the initial operation affected the bilateral leaflets in 37 (43%) patients, the anterior leaflet in 30 (35%) patients and the posterior leaftlet in 19 (22%) patients. Median duration from first operation to reoperation was 47.5 (interquartile range 4.8-85.8) months. Reoperation indication included recurrent mitral regurgitation alone in 59 patients, haemolysis combined with recurrent mitral regurgitation in 15 patients, infectious endocarditis combined with recurrent mitral regurgitation in 8 patients, mitral stenosis in 2 patients and left ventricular pseudoaneurysm in 2 patients. The cause of MV repair failure was valve-related in 61 (71%) patients, procedure-related in 20 (23%) patients and both in 5 (6%) patients. Re-MVP was successful in 23 (27%) patients. Re-MVP was more common in patients with procedure-related failure, which occurred earlier than valve-related failure. Freedom from all-cause death was significantly better after Re-MVP. The 5-year freedom from reoperation after Re-MVP was 95.7%. Re-MVP was more common in patients with procedure-related failure, which occurred earlier than valve-related failure. Durability of re-repaired MVs and survival of re-repaired patients were acceptable.

  14. Shape Memory Actuated Normally Open Permanent Isolation Valve

    Science.gov (United States)

    Ramspacher, Daniel J. (Inventor); Bacha, Caitlin E. (Inventor)

    2017-01-01

    A valve assembly for an in-space propulsion system includes an inlet tube, an outlet tube, a valve body coupling the inlet tube to the outlet tube and defining a propellant flow path, a valve stem assembly disposed within the valve body, an actuator body coupled to the valve body, the valve stem assembly extending from an interior of the valve body to an interior of the actuator body, and an actuator assembly disposed within the actuator body and coupled to the valve stem assembly, the actuator assembly including a shape memory actuator member that when heated to a transition temperature is configured to enable the valve stem assembly to engage the outlet tube and seal the propellant flow path.

  15. Baseline MDCT findings after prosthetic heart valve implantation provide important complementary information to echocardiography for follow-up purposes

    Energy Technology Data Exchange (ETDEWEB)

    Sucha, Dominika; Mali, Willem P.T.M.; Habets, Jesse [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Chamuleau, Steven A.J. [University Medical Center Utrecht, Department of Cardiology, Utrecht (Netherlands); Symersky, Petr [VU Medical Center, Department of Cardiothoracic Surgery, Amsterdam (Netherlands); Meijs, Matthijs F.L. [Thoraxcentrum Twente, Medisch Spectrum Twente, Department of Cardiology, Enschede (Netherlands); Brink, Renee B.A. van den [Academic Medical Center, Department of Cardiology, Amsterdam (Netherlands); Mol, Bas A.J.M. de [Academic Medical Center, Department of Cardiothoracic Surgery, Amsterdam (Netherlands); Herwerden, Lex A. van [University Medical Center Utrecht, Department of Cardiothoracic Surgery, Utrecht (Netherlands); Budde, Ricardo P.J. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Erasmus University Medical Center, Department of Radiology, Rotterdam (Netherlands)

    2016-04-15

    Recent studies have proposed additional multidetector-row CT (MDCT) for prosthetic heart valve (PHV) dysfunction. References to discriminate physiological from pathological conditions early after implantation are lacking. We present baseline MDCT findings of PHVs 6 weeks post implantation. Patients were prospectively enrolled and TTE was performed according to clinical guidelines. 256-MDCT images were systematically assessed for leaflet excursions, image quality, valve-related artefacts, and pathological and additional findings. Forty-six patients were included comprising 33 mechanical and 16 biological PHVs. Overall, MDCT image quality was good and relevant regions remained reliably assessable despite mild-moderate PHV-artefacts. MDCT detected three unexpected valve-related pathology cases: (1) prominent subprosthetic tissue, (2) pseudoaneurysm and (3) extensive pseudoaneurysms and valve dehiscence. The latter patient required valve surgery to be redone. TTE only showed trace periprosthetic regurgitation, and no abnormalities in the other cases. Additional findings were: tilted aortic PHV position (n = 3), pericardial haematoma (n = 3) and pericardial effusion (n = 3). Periaortic induration was present in 33/40 (83 %) aortic valve patients. MDCT allowed evaluation of relevant PHV regions in all valves, revealed baseline postsurgical findings and, despite normal TTE findings, detected three cases of unexpected, clinically relevant pathology. (orig.)

  16. Valve-in-valve outcome: design impact of a pre-existing bioprosthesis on the hydrodynamics of an Edwards Sapien XT valve.

    Science.gov (United States)

    Doose, Christian; Kütting, Maximilian; Egron, Sandrine; Farhadi Ghalati, Pejman; Schmitz, Christoph; Utzenrath, Marc; Sedaghat, Alexander; Fujita, Buntaro; Schmitz-Rode, Thomas; Ensminger, Stephan; Steinseifer, Ulrich

    2017-03-01

    Bioprosthetic aortic heart valves are increasingly implanted in younger patients. Therefore, a strategy for potential valve failure should be developed before implanting the 'first valve'. The goal of this in vitro study was to provide insight into the effects of the design of a bioprosthesis on a valve-in-valve implanted Sapien XT valve. The hydrodynamic performance of a 23-mm Sapien XT valve implanted in Vascutek Aspire, Edwards Perimount, Medtronic Mosaic and St. Jude Medical Trifecta heart valves was investigated in a left heart simulator. In addition to the hydrodynamic results, the leaflet dynamics were analysed in high-speed video recordings of the tests. All valve-in-valve combinations in this study fulfilled the minimum acceptance criteria defined by relevant approval standards (e.g. ISO 5840) but displayed significant differences in their performances. Small inner diameters of the bioprostheses were associated with increased mean pressure gradients, decreased effective orifice areas and geometric opening areas as well as with pin-wheeling and uneven leaflet motion. In addition, implantation in bioprostheses with internally mounted leaflets was associated with lower paravalvular leakage. The results of this study suggest that a surgical bioprosthesis with a large inner diameter and internally mounted leaflets improves the heamodynamics and potentially the durability of a valve-in-valve combination. These results should give the attending physicians critical information to consider when deciding on a bioprosthesis for younger patients.

  17. Mitral valve repair for degenerative mitral valve disease: surgical approach, patient selection and long-term outcomes.

    Science.gov (United States)

    Coutinho, Gonçalo F; Antunes, Manuel J

    2017-11-01

    Mitral valve repair (MVRepair) has become the procedure of choice to correct severe degenerative mitral regurgitation (MR), due to its documented superiority to valve replacement regarding long-term survival, freedom from valve-related adverse events and preservation of left ventricular (LV) function. The refinement of MVRepair techniques has rendered almost all valves (more than 95%) amenable to repair with a 15-year freedom from reoperation of 90%. The concept of 'centres of excellence for MVRepair' has emerged, encouraging referring doctors to select the most experienced institutions or individual surgeons to deal with the most complex cases, based on repair volume, appropriate peri-procedural imaging and data regarding expected outcomes (repair, mortality and durability of repair). Based on the good results, operating on asymptomatic patients with severe MR is now widely accepted, prophylactically avoiding the dire consequences of chronic MR, such as LV function deterioration/enlargement, and development of atrial fibrillation and pulmonary hypertension. In reference centres, where the repair rate is over 95% for all types of disease with <1% mortality, it has become standard practice in nearly 50%-60% of all patients submitted to MVRepair. Finally, recent advances in the surgical treatment with the purpose of reducing invasiveness and surgical trauma, through partial sternotomy or mini-thoracotomy (video-assisted with or without robotics), are now being increasingly performed in 20%-30% of centres, claiming comparable results to conventional surgery. In addition, transcatheter technology, particularly the MitraClip, is evolving and treading its way in the treatment of high-risk patients with severe MR, but the results are still short of ideal. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  18. THE PROGNOSIS IN TRANSCATHETER AORTIC VALVE IMPLANTATION

    Directory of Open Access Journals (Sweden)

    T. E. Imaev

    2016-01-01

    Full Text Available Aim. To study the effect of transcatheter aortic valve implantation (TAVI, performed by different types of prostheses and various surgical access, on the prognosis of patients with critical aortic stenosis and comorbidities.Material and methods. Patients (n=130 that had consistently performed 80 TAVI by Edwards valve transfemoral (n=50 and transapical (n=30 access, as well as 50 transcatheter aortic valve replacement by CoreValve system were included into the study. Complications including perioperative mortality, total 30-day mortality, as well as post-hospital mortality were registered during aortic valve replacement, immediately after surgery, before the expiry of 30 days. Mean follow-up was 2.2 years (range 0.2 to 5.2 years.Results. Hospital mortality was on average 6.9%. 121 patients had been discharged from the department after the surgery. The number of deaths in the post-hospital period was 14.8%. Valve type and the type of access had no effect on post-hospital mortality. Men died more than 2.5 times often than women, regardless of age. Atrioventricular block, pacemaker implantation, and history of chronic obstructive pulmonary disease were the most significant prognostic factors. An important role of minor stroke and renal failure should be noted. Mortality did not depend on the surgical access or valve type. All parameters characterizing the intervention were significantly associated with mortality, both during and after surgery. The proportion of survivors at the end of the first year of observation using Corvalve system was 86.9%, Edwards valve by transfemoral access - 88% and Edwards valve by transapical access – 85.4% (insignificant differences for all groups, p>0.05. Two-year survival was 77.5%, 82.5% and 82.7%, respectively (also insignificant differences for all groups, p>0.05.Conclusion. TAVI is the method of choice, reasonable alternative approach for surgical valve replacement in patients with high surgical risk, although

  19. Transcatheter Aortic Valve Replacement With Early- and New-Generation Devices in Bicuspid Aortic Valve Stenosis

    DEFF Research Database (Denmark)

    Yoon, Sung Han; Lefèvre, Thierry; Ahn, Jung Ming

    2016-01-01

    Background Few studies have evaluated the clinical outcomes of transcatheter aortic valve replacement (TAVR) in patients with bicuspid aortic valve stenosis (AS). Particularly, limited data exist comparing the results of TAVR with new-generation devices versus early-generation devices.  Objective...

  20. Anterior mitral valve aneurysm perforation secondary to aortic valve endocarditis detected by Doppler colour flow mapping.

    Science.gov (United States)

    Decroly, P; Vandenbossche, J L; Englert, M

    1989-02-01

    We report a case of mitral valve aneurysm formation and perforation, secondary to Streptococcus sanguis endocarditis of the aortic valve. Aneurysm formation was documented by cross-sectional echocardiography and its perforation was established by Doppler colour flow mapping, and subsequently confirmed at surgery.

  1. In Vitro Evaluation of the iValve : A Novel Hands-Free Speech Valve

    NARCIS (Netherlands)

    van der Houwen, E.B.; van Kalkeren, T.A.; Burgerhof, J.G.; van der Laan, B.F.; Verkerke, G.J.

    2011-01-01

    Objectives: We performed in vitro evaluation of a novel, disposable, automatic hands-free tracheostoma speech valve for laryngectomy patients based upon the principle of inhalation. The commercially available automatic speech valves close upon strong exhalation and open again when the pressure

  2. Bjork-Shiley convexoconcave valves: Susceptibility artifacts at brain MR imaging and mechanical valve fractures

    NARCIS (Netherlands)

    van Gorp, Maarten J.; van der Graaf, Yolanda; de Mol, Bas A. J. M.; Bakker, Chris J. G.; Witkamp, Theo D.; Ramos, Lino M. P.; Mali, Willem P. T. M.

    2004-01-01

    PURPOSE: To assess the relationship between heart valve history and susceptibility artifacts at magnetic resonance (MR) imaging of the brain in patients with Bjork-Shiley convexoconcave (BSCC) valves. MATERIALS AND METHODS: MR images of the brain were obtained in 58 patients with prosthetic heart

  3. A WEAR MODEL FOR DIESEL ENGINE EXHAUST VALVES

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL

    2009-11-01

    run for hundreds of hours in heavy-duty diesels provided insights into the kinds of complexity that the contact conditions in engines can produce, and suggested the physical basis for the current approach to modeling. The model presented here involves four terms, two representing the valve response and two for its mating seat material. The model's structure assumes that wear that takes place under a complex combination of plastic deformation, tangential shear, and oxidation. Tribolayers form, are removed, and may reform. Layer formation affects the friction forces in the interface, and in turn, the energy available to do work on the materials to cause wear. To provide friction data for the model at various temperatures, sliding contact experiments were conducted from 22 to 850 C in a pin-on-disk apparatus at ORNL. In order to account for the behavior of different materials and engine designs, parameters in all four terms of the model can be adjusted to account for wear-in and incubation periods before the dominant wear processes evolve to their steady-state rates. For example, the deformation rate is assumed to be maximum during the early stages of operation, and then, due to material work-hardening and the increase in nominal contact area (which reduces the load per unit area), decreases to a lower rate at long times. Conversely, the rate of abrasion increases with time or number of cycles due to the build-up of oxides and tribo-layers between contact surfaces. The competition between deformation and abrasion results in complex, non-linear behavior of material loss per cycle of operation. Furthermore, these factors are affected by valve design features, such as the angle of incline of the valve seat. Several modeling scenarios are presented to demonstrate how the wear profile versus number of cycles changes in response to: (a) different relative abrasion rates of the seat and valve materials, (b) the friction coefficient as a function of temperature, (c) the

  4. [Heart valve prosthesis and pregnancy].

    Science.gov (United States)

    Ben-Ismail, M; Fekih, M; Taktak, M; Chelli, M

    1979-02-01

    Sixteen pregnancies were followed up in 13 patients with prosthetic heart valves: 8 pregnancies went to term under oral anticoagulation, 4 under heparin and 4 without anticoagulation. 9 healthy normal children were delivered; there were 2 still births and 5 abortions. On the maternal side 3 haemorrhages and thromboembolic episodes which involved 2 patients on heparin, one of whom died, were observed. The following points are apparent from our observations and a review of the existing medical literature: --the risk of thromboembolism is not increased. The marked clotting tendency of maternal blood post-partum contraindicates the withdrawal of anticoagulants during this critical period; --haemorrhagic complications are common with anticoagulants; --foetal loss is greatly increased; --the teratogenecity of vitamin-K antagonists is certain, but the risk is small. The problems of anticoagulation are discussed; theoretically heparin should be given during the 1st trimestre and from the 38th week to the second post-partum week. The patients should be closely supervised by both obstetrician and cardiologist and hospitalisation is advised for the last month of pregnancy. Normal vaginal delivery is usually possible.

  5. Simulant Development for Hanford Tank Farms Double Valve Isolation (DVI) Valves Testing

    Energy Technology Data Exchange (ETDEWEB)

    Wells, Beric E.

    2012-12-21

    Leakage testing of a representative sample of the safety-significant isolation valves for Double Valve Isolation (DVI) in an environment that simulates the abrasive characteristics of the Hanford Tank Farms Waste Transfer System during waste feed delivery to the Waste Treatment and Immobilization Plant (WTP) is to be conducted. The testing will consist of periodic leak performed on the DVI valves after prescribed numbers of valve cycles (open and close) in a simulated environment representative of the abrasive properties of the waste and the Waste Transfer System. The valve operations include exposure to cycling conditions that include gravity drain and flush operation following slurry transfer. The simulant test will establish the performance characteristics and verify compliance with the Documented Safety Analysis. Proper simulant development is essential to ensure that the critical process streams characteristics are represented, National Research Council report “Advice on the Department of Energy's Cleanup Technology Roadmap: Gaps and Bridges”

  6. Thrombolytic therapy in prosthetic valve thrombosis during early pregnancy

    Directory of Open Access Journals (Sweden)

    B.C. Srinivas

    2012-01-01

    Full Text Available Regardless of the improvements in the design of prosthetic heart valves and the use of anticoagulation, systemic embolism and valve thrombosis remains the most dreaded complications of mechanical heart valve replacement. A course of thrombolytic therapy may be considered as a first-line therapy for prosthetic heart valve thrombosis. The safety of thrombolysis in early pregnancy is not known. We describe a primigravida with mitral valve replacement status presenting with acute prosthetic valve thrombosis and treated successfully with intravenous streptokinase.

  7. Fluid Dynamic Characterization of a Polymeric Heart Valve Prototype (Poli-Valve) tested under Continuous and Pulsatile Flow Conditions

    Science.gov (United States)

    De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D.; Costantino, Maria Laura

    2016-01-01

    Introduction Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy, the latter display better fluid dynamic behaviour but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the haemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of two groups of newly developed supra-annular tri-leaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. Methods Two types of Poli-Valves made of SBC differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. An ad - hoc designed pulse duplicator allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the valve’s behaviour. Results Both types Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by ISO 5840 Standard. Results were compared with five mechanical heart valves (MHVs) and five tissue heart valves (THVs), currently available on the market. Conclusion Based on these results, polymeric heart valves based on styrenic block copolymers, as Poli-Valves are, can be considered as promising alternative for heart valve replacement in near future. PMID:26689146

  8. Pilot licensing after aortic valve surgery.

    Science.gov (United States)

    Syburra, Thomas; Schnüriger, Hans; Kwiatkowski, Barbara; Graves, Kirk; Reuthebuch, Oliver; Genoni, Michele

    2010-05-01

    Bicuspid aortic valve is the most common congenital heart malformation, and a high percentage of patients with this condition will develop complications over time. It is rare that pilots undergo aortic valve surgery, and the confirmation of flight-licensing requirements after aortic valve replacement (AVR) is a challenge for the patient's cardiac surgeon and, particularly, for the Aeromedical Examiner (AME). Only AMEs are able to determine the flight status of pilots. Furthermore, in military and in civil aviation (e.g., Red Bull Air Race), the high G-load environment experienced by pilots is an exceptional physiological parameter, which must be considered postoperatively. A review was conducted of the aeronautical, surgical and medical literature, and of European pilot-licensing regulations. Case studies are also reported for two Swiss Air Force pilots. According to European legislation, pilots can return to flight duty from the sixth postoperative month, with the following limitations: that an aortic bioprosthesis presents no restrictions in cardiac function, requires no cardioactive medications, yet requires a flight operation with co-pilot, the avoidance of accelerations over +3 Gz and, in military aviation, restricts the pilot to non-ejection-seat aircraft. The patient follow up must include both echocardiographic and rhythm assessments every six months. Mechanical prostheses cannot be certified because the required anticoagulation therapy is a disqualifying condition for pilot licensing. Pilot licensing after aortic valve surgery is possible, but with restrictions. The +Gz exposition is of concern in both military and civilian aviation (aerobatics). The choice of bioprosthesis type and size is determinant. Pericardial and stentless valves seem to show better flow characteristics under high-output conditions. Repetitive cardiological controls are mandatory for the early assessment of structural valve disease and rhythm disturbances. A pre-emptive timing is

  9. Lined 10'' butterfly valve outlasts competitive valves in brine filter system

    Energy Technology Data Exchange (ETDEWEB)

    Gaines, A.

    1982-03-01

    One of the world's largest chlorine production units located in the Gulf Coast area has an extensive brine piping system with a large number of valves. Some of the valves performed well but many failed to meet the service requirements, especially in the brine filtering system with the salt solution at ambient temperatures and pressures about 100 psi. One of these was a 10'' valve. Various types of gear-operated butterfly valves, with an elastomer lining to withstand the somewhat corrosive solution, had been tried but developed leaks and had to be repaired or replaced after 4 to 6 months. The valves became difficult or impossible to operate in some cases when brine leaking past the stem seal attacked the inner surface of the metal valve body and the liner was dislodged by the movement of the disc. In September 1980, a 10'' butterfly valve specifically designed for bubble-tight shut off and zero stem leakage was installed in the brine filter line on a trial basis. The valve has a 1-piece, epoxy-coated ductile iron body with a molded one-piece liner of Hypalon rubber, and a stainless steel stem and disc with splines instead of pins to provide a trouble-free connection. The stem is positively sealed against leakage by a patented spherical machining process on both the disc and the liner. The valve was furnished with a variable ratio gear actuator that has higher torque output when the disc begins to make contact with the seat to assure a bubble-tight shutoff with minimum input torque. The butterfly valve has provided leaktight performance since it was installed in September 1980 and is still easy to open and close by the geared actuator.

  10. Loss of Axin2 results in impaired heart valve maturation and subsequent myxomatous valve disease.

    Science.gov (United States)

    Hulin, Alexia; Moore, Vicky; James, Jeanne M; Yutzey, Katherine E

    2017-01-01

    Myxomatous valve disease (MVD) is the most common aetiology of primary mitral regurgitation. Recent studies suggest that defects in heart valve development can lead to heart valve disease in adults. Wnt/β-catenin signalling is active during heart valve development and has been reported in human MVD. The consequences of increased Wnt/β-catenin signalling due to Axin2 deficiency in postnatal valve remodelling and pathogenesis of MVD were determined. To investigate the role of Wnt/β-catenin signalling, we analysed heart valves from mice deficient in Axin2 (KO), a negative regulator of Wnt/β-catenin signalling. Axin2 KO mice display enlarged mitral and aortic valves (AoV) after birth with increased Wnt/β-catenin signalling and cell proliferation, whereas Sox9 expression and collagen deposition are decreased. At 2 months in Axin2 KO mice, the valve extracellular matrix (ECM) is stratified but distal AoV leaflets remain thickened and develop aortic insufficiency. Progressive myxomatous degeneration is apparent at 4 months with extensive ECM remodelling and focal aggrecan-rich areas, along with increased BMP signalling. Infiltration of inflammatory cells is also observed in Axin2 KO AoV prior to ECM remodelling. Overall, these features are consistent with the progression of human MVD. Finally, Axin2 expression is decreased and Wnt/β-catenin signalling is increased in myxomatous mitral valves in a murine model of Marfan syndrome, supporting the importance of Wnt/β-catenin signalling in the development of MVD. Altogether, these data indicate that Axin2 limits Wnt/β-catenin signalling after birth and allows proper heart valve maturation. Moreover, dysregulation of Wnt/β-catenin signalling resulting from loss of Axin2 leads to progressive MVD. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For Permissions, please email: journals.permissions@oup.com.

  11. Comparison of the occurrence of thromboembolic and bleeding complications in patients with mechanical heart valve prosthesis with one and two leaflets in the mitral position

    Science.gov (United States)

    de Campos, Nelson Leonardo Kerdahi Leite

    2014-01-01

    Introduction Patients with mechanical heart valve prostheses must continuously be treated with oral anticoagulants to prevent thromboembolic events related to prosthetesis. These patients should be continually evaluated for the control of oral anticoagulation. Objective To compare the occurrence of thromboembolic and hemorragic complications in patients with mechanical heart valve prosthesis with one (mono) and two (bi) leaflets in the mitral position in anticoagulant therapy. Methods We studied the 10-year interval, 117 patients with prosthesis in the mitral position, 48 with prosthetic single leaflet and 69 with two leaflets. We evaluated the occurrence of thromboembolic and hemorrhagic major and minor degree under gravity. The results are presented in an actuarial study and the frequency of occurrence of linear events. Results The actuarial survival curves showed that over time, patients with prosthetic heart valve with one leaflet were less free of thromboembolic complications than patients with two leaflet prosthetic valve, while the latter (two leaflet) were less free of hemorrhagic accidents. The linearized frequency of occurrence of thromboembolism were higher in patients with mono leaflet prosthesis. Bleeding rates were higher for patients with bi leaflet prosthetic valve. Conclusion Patients with mono leaflet prosthetic heart valve showed that they are more prone to the occurrence of serious thromboembolic events compared to those with bi leaflet prosthetic valve. Patients with bi leaflet prosthetic valve had more bleeding than patients with mono leaflet prosthetic valve, however this difference was restricted to the bleeding of minor nature. PMID:24896164

  12. Echocardiographic evaluation of mitral durability following valve repair in rheumatic mitral valve disease: impact of Maze procedure.

    Science.gov (United States)

    Kim, Gwan Sic; Lee, Chee Hoon; Kim, Joon Bum; Jung, Sung-Ho; Choo, Suk Jung; Chung, Cheol Hyun; Lee, Jae Won

    2014-01-01

    The data on echocardiographic evaluation of mitral durability after rheumatic mitral repair is scarce. A total of 193 patients (mean age, 39.4 ± 12.8 years; 154 females) who underwent mitral valve repair for rheumatic valve disease from 1997 to 2010 were included in the study. A Maze operation was performed in 90.3% (n = 102) of the patients with atrial fibrillation (n = 113). Survival, valve-related complications, and echocardiographic data were evaluated. Mitral regurgitation was the predominant disease in 75.6% of patients (n = 146). There was one early death (0.5%) . During the mean follow-up period of 76.7 ± 45.6 months, there were 9 late deaths and 5 mitral reoperations. Valve-related, event-free survival at 10 years was 85.5% ± 3.3%. In serial postoperative echocardiographic evaluations (mean follow-up duration, 53.7 ± 43.5 months), 40 patients showed either mitral regurgitation (>mild; n = 31) or mitral stenosis (mitral valve area ≤1.5 cm(2); n = 9). At 10 years, 66.4% ± 5.4% of the patients did not have moderate to severe mitral dysfunction. By multivariate analysis, no Maze operation for atrial fibrillation was an independent predictor of mitral dysfunctions (hazard ratio, 3.72; 95% confidence interval, 1.47-9.42; P = .005), whereas the presence of hypertension had borderline significance (hazard ratio, 3.15; 95% confidence interval, 0.96-10.38; P = .059). Although rheumatic mitral repair showed excellent long-term clinical outcomes, a significant proportion of patients experienced moderate to severe mitral dysfunctions postoperatively. Atrial fibrillation without a Maze procedure increased significantly the risks of mitral dysfunctions and adverse outcomes. Therefore, routine performance of a Maze procedure is warranted in the presence of atrial fibrillation whenever possible. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  13. LMFBR large valve development. Comparison study of advantages and disadvantages of foreign design of offset pivot butterfly valves with AMCO's offset pivot ball valve

    Energy Technology Data Exchange (ETDEWEB)

    DeWall, L.

    1975-02-01

    The purpose of this effort was to compare the advantages and disadvantages of foreign designs of offset pivot butterfly valves presented during a specialists meeting on Operating Experience and Design Criteria of Sodium Valves with the characteristics of the present AMCO offset pivot ball valve design concept. In addition, the comparison was directed to indicating if work on a butterfly concept should be initiated by AMCO. This work could be in parallel with or in lieu of, the present AMCO effort on an offset pivot ball valve for isolation valve purposes.

  14. Durability of pericardial versus porcine bioprosthetic heart valves.

    Science.gov (United States)

    Grunkemeier, Gary L; Furnary, Anthony P; Wu, YingXing; Wang, Lian; Starr, Albert

    2012-12-01

    To compare the probability, and modes, of explantation for Carpentier-Edwards pericardial versus porcine valves. Our porcine series began in 1974 and our pericardial series in 1991, with annual prospective follow-up. We used the Kaplan-Meier method and Cox regression for estimation and analysis of patient mortality, and the cumulative incidence function and competing risks regression for estimation and analysis of valve durability. Through the end of 2010, we had implanted 506 porcine and 2449 pericardial aortic valves and 181 porcine and 163 pericardial mitral valves. The corresponding total and maximum follow-up years were 3471 and 24, 11,517 and 18, 864 and 22, and 645 and 9. The corresponding probabilities (cumulative incidence function) of any valve explant were 7%, 8%, 22%, and 8%, and of explant for structural valve deterioration were 4%, 5%, 16%, and 5% at 15 years for the first 3 series and at 8 years for the fourth (pericardial mitral valve) series. Using competing risks regression for structural valve deterioration explant, with age, gender, valve size, and concomitant coronary bypass surgery as covariates, a slight (subhazard ratio, 0.79), but nonsignificant, protective effect was found for the pericardial valve in the aortic position and a greater (subhazard ratio, 0.31) and almost significant (P = .08) protective effect of the pericardial valve in the mitral position. Leaflet tear was responsible for 61% of the structural valve deterioration explants in the porcine series and 46% in the pericardial series. Using competing risks regression, the pericardial valve had a subhazard ratio for structural valve deterioration explant of less than 1 in both positions, approaching statistical significance in the mitral position. The mode of structural valve deterioration was predominantly leaflet tear for porcine valves and fibrosis/calcification for pericardial valves. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc

  15. Survey of industrial coal conversion equipment capabilities: valves

    Energy Technology Data Exchange (ETDEWEB)

    Bush, W. A.; Slade, E. C.

    1978-06-01

    A survey of the industrial capabilities of the valve and valve-actuator industry to supply large, high-pressure stop valves for the future coal conversion industry is presented in this report. Also discussed are development and testing capabilities of valve and valve-actuator manufacturers and anticipated lead times required to manufacture advanced design valves for the most stringent service applications. Results indicate that the valve and valve-actuator industry is capable of manufacturing in quantity equipment of the size and for the pressure and temperature ranges which would be required in the coal conversion industry. Valve manufacturers do not, however, have sufficient product application experience to predict the continuing functional ability of valves used for lock-hopper feeders, slurry feeders, and slag-char letdown service. Developmental and testing efforts to modify existing valve designs or to develop new valve concepts for these applications were estimated to range from 1 to 6 years. A testing facility to simulate actuation of critical valves under service conditions would be beneficial.

  16. Cardiac crossroads: deciding between mechanical or bioprosthetic heart valve replacement

    Directory of Open Access Journals (Sweden)

    Maggie N Tillquist

    2011-02-01

    Full Text Available Maggie N Tillquist1, Thomas M Maddox21School of Medicine, University of Colorado Denver, Denver, CO, USA; 2VA Eastern Colorado Health Care System, and Department of Medicine (Cardiology, University of Colorado Denver, Denver, CO, USAAbstract: Nearly 15 million people in the United States suffer from either aortic or mitral valvular disease. For patients with severe and symptomatic valvular heart disease, valve replacement surgery improves morbidity and mortality outcomes. In 2009, 90,000 valve replacement surgeries were performed in the United States. This review evaluates the advantages and disadvantages of mechanical and bioprosthetic prosthetic heart valves as well as the factors for consideration in deciding the appropriate valve type for an individual patient. Although many caveats exist, the general recommendation is for patients younger than 60 to 65 years to receive mechanical valves due to the valve's longer durability and for patients older than 60 to 65 years to receive a bioprosthetic valve to avoid complications with anticoagulants. Situations that warrant special consideration include patient co-morbidities, the need for anticoagulation, and the potential for pregnancy. Once these characteristics have been considered, patients' values, anxieties, and expectations for their lifestyle and quality of life should be incorporated into final valve selection. Decision aids can be useful in integrating preferences in the valve decision. Finally, future directions in valve technology, anticoagulation, and medical decision-making are discussed.Keywords: prosthetic heart valves, patient preference, valve type, anticoagulant, structural valve deterioration 

  17. Valvular Heart Disease in Adults: Management of Prosthetic Heart Valves.

    Science.gov (United States)

    Trujillo, John F; Hollenberg, Steven M

    2017-06-01

    Patients undergoing cardiac valve replacement may receive mechanical or bioprosthetic valves. Mechanical valves require lifelong anticoagulation but are durable and the need for a second surgery is up to eightfold times less than with bioprosthetic valves. Bioprosthetic valves do not require lifelong anticoagulation and thus are associated with fewer bleeding complications but they are less durable and associated with higher morbidity and mortality rates, particularly in younger patients. Anticoagulation with mechanical valves is achieved using warfarin; use of direct-acting oral anticoagulants is not indicated. Concomitant low-dose aspirin is recommended for patients with mechanical valves and as sole thromboembolism prophylaxis for patients receiving aortic or mitral bioprosthetic valves. If a patient taking warfarin is to undergo a surgical procedure that requires interruption of anticoagulation, bridging therapy with heparin is indicated if the patient has a mechanical aortic valve and any risk of thromboembolism, an older-generation mechanical aortic valve, or a mechanical mitral valve. Warfarin is teratogenic; pregnant women should take heparin. Patients with mechanical or bioprosthetic valves should receive antibiotic prophylaxis before some dental and surgical procedures to prevent endocarditis. Thrombolytic therapy should be considered in patients who develop a thrombus on a valve that does not resolve with heparin. Written permission from the American Academy of Family Physicians is required for reproduction of this material in whole or in part in any form or medium.

  18. Risk-based approach to appraise valve closure in the clam Corbicula fluminea in response to waterborne metals

    Energy Technology Data Exchange (ETDEWEB)

    Liao, C.-M. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, Taiwan 10617 (China)]. E-mail: cmliao@ntu.edu.tw; Jou, L.-J. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, Taiwan 10617 (China); Department of Biomechatronic Engineering, National Ilan University, Ilan, Taiwan 260 (China); Chen, B.-C. [Department of Post-Modern Agriculture, Mingdao University, Changhua, Taiwan 52345 (China)

    2005-05-01

    We developed a risk-based approach to assess how the valve closure behavior of Asiatic clam Corbicula fluminea responds to waterborne copper (Cu) and cadmium (Cd). We reanalyzed the valve closure response data from published literature to reconstruct the response time-dependent dose-response profiles based on an empirical three-parameter Hill equation model. We integrated probabilistic exposure profiles of measured environmental Cu and Cd concentrations in the western coastal areas of Taiwan with the reconstructed dose-response relationships at different integration times of response to quantitatively estimate the valve response risk. The risk assessment results implicate exposure to waterborne Cu and Cd may pose no significant risk to clam valve activity in the short-time response periods (e.g., <30 min), yet a relative high risk for valve closure response to waterborne Cu at response times greater than 120 min is alarming. We successfully linked reconstructed dose-response profiles and EC50-time relationships associated with the fitted daily valve opening/closing rhythm characterized by a three-parameter lognormal function to predict the time-varying bivalve closure rhythm response to waterborne metals. We parameterized the proposed predictive model that should encourage a risk-management framework for discussion of future design of biological monitoring systems. - A model was developed to link valve closure in clams to concentrations of metals in water.

  19. Valve-gaping behavior of raft-cultivated mussels in the Ría de Arousa, Spain

    Directory of Open Access Journals (Sweden)

    Luc A. Comeau

    2018-02-01

    Full Text Available We describe the valve-opening behavior of raft-cultivated mussels (Mytilus galloprovincialis in the Ría de Arousa (Arousa estuary, Spain. Eight rope-grown mussels [mean ± standard error (SEM, shell length 61.6 ± 2.1 mm] were connected to a non-invasive valvometry apparatus that monitored (one measurement min−1 the magnitude of valve openness systematically over a 10 day period. It was found that valves were open 97.5 ± 1.3% percent of the time. Valve closures were not synchronized among the eight monitored mussels, suggesting that feeding cessation was physiologically-regulated rather than environmentally-mediated. The opening amplitudes that were most frequently observed were in the range of 60–90%, indicating that, when open, valves are usually opened relatively close to their maximum possible extent. The majority (7/8 of mussels displayed a circadian rhythm (τ = 24.0 h in valve opening amplitude. They tended to exhibit maximum valve opening during nighttime and minimum opening during daytime. It is possible that the light:dark cycle represents an environmental zeitgeber entraining an endogenous gaping rhythm in this bivalve.

  20. Transient flow characteristics of a high speed rotary valve

    Science.gov (United States)

    Browning, Patrick H.

    Pressing economic and environmental concerns related to the performance of fossil fuel burning internal combustion engines have revitalized research in more efficient, cleaner burning combustion methods such as homogeneous charge compression ignition (HCCI). Although many variations of such engines now exist, several limiting factors have restrained the full potential of HCCI. A new method patented by West Virginia University (WVU) called Compression Ignition by Air Injection (CIBAI) may help broaden the range of effective HCCI operation. The CIBAI process is ideally facilitated by operating two synchronized piston-cylinders mounted head-to-head with one of the cylinders filled with a homogeneous mixture of air and fuel and the other cylinder filled with air. A specialized valve called the cylinder connecting valve (CCV) separates the two cylinders, opens just before reaching top dead center (TDC), and allows the injection air into the charge to achieve autoignition. The CCV remains open during the entire power stroke such that upon ignition the rapid pressure rise in the charge cylinder forces mass flow back through the CCV into the air-only cylinder. The limited mass transfer between the cylinders through the CCV limits the theoretical auto ignition timing capabilities and thermal efficiency of the CIBAI cycle. Research has been performed to: (1) Experimentally measure the transient behavior of a potential CCV design during valve opening between two chambers maintained at constant pressure and again at constant volume; (2) Develop a modified theoretical CCV mass flow model based upon the measured cold flow valve performance that is capable of predicting the operating conditions required for successful mixture autoignition; (3) Make recommendations for future CCV designs to maximize CIBAI combustion range. Results indicate that the modified-ball CCV design offers suitable transient flow qualities required for application to the CIBAI concept. Mass injection events

  1. Osseous and chondromatous metaplasia in calcific aortic valve stenosis.

    Science.gov (United States)

    Torre, Matthew; Hwang, David H; Padera, Robert F; Mitchell, Richard N; VanderLaan, Paul A

    2016-01-01

    Aortic valve replacement for calcific aortic valve stenosis is one of the more common cardiac surgical procedures. However, the underlying pathophysiology of calcific aortic valve stenosis is poorly understood. We therefore investigated the histologic findings of aortic valves excised for calcific aortic valve stenosis and correlated these findings with their associated clinical features. We performed a retrospective analysis on 6685 native aortic valves excised for calcific stenosis and 312 prosthetic tissue aortic valves with calcific degeneration at a single institution between 1987 and 2013. Patient demographics were correlated with valvular histologic features diagnosed on formalin-fixed, decalcified, and paraffin embedded hematoxylin and eosin stained sections. Of the analyzed aortic valves, 5200 (77.8%) were tricuspid, 1473 (22%) were bicuspid, 11 (0.2%) were unicuspid, and 1 was quadricuspid. The overall prevalence of osseous and/or chondromatous metaplasia was 15.6%. Compared to tricuspid valves, bicuspid valves had a higher prevalence of metaplasia (30.1% vs. 11.5%) and had an earlier mean age of excision (60.2 vs. 75.1 years old). In addition, the frequency of osseous metaplasia and/or chondromatous metaplasia increased with age at time of excision of bicuspid aortic valves, while tricuspid aortic valves showed the same incidence regardless of patient age. Males had a higher prevalence of metaplasia in both bicuspid (33.5% vs. 22.3%) and tricuspid (13.8% vs. 8.6%) aortic valves compared to females. Osseous metaplasia and/or chondromatous metaplasia was also more common in patients with bicuspid aortic valves and concurrent chronic kidney disease or atherosclerosis than in those without (33.6% vs. 28.3%). No osseous or chondromatous metaplasia was observed within the cusps of any of the prosthetic tissue valves. Osseous and chondromatous metaplasia are common findings in native aortic valves but do not occur in prosthetic tissue aortic valves. Bicuspid

  2. Status of Functional Qualification System for Nuclear Valve Assembly in KIMM

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. H.; Park, T. J.; Kim, Y. J. [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2016-05-15

    In this paper, the status of the test facility, the basic concept of the ASME QME-1 test, and the future work are presented. The measured performance parameter, such as pressure, temperature, flow rate, thrust, stroke, and time, is used for the maintenance method and the evaluation of the aging and fatigue in the operating valve. In these days, the survival of the safety related valve in severe accident is important issue. In Korea Institute of Machinery and Materials (KIMM), the functional facility and related Quality Assure (QA) system are made. In addition, the qualification research was made for the functional test of the valve as ASME QME-1. The methodology is based on the ASME QME-1 1997. But the future work for the ASME QME-1 2007 was performed. In real situation, the engineering work is needed for the functional test of the nuclear valve in QA system. So the research work for the qualification is needed. The functional qualification of the valve in the nuclear power plant is performed in KIMM The development of the research and facility required in the functional qualification is in progress. Now the functional qualification is possible domestically, that was impossible in previous time due to the lack of qualification technology and facility.

  3. Electrical Textile Valves for Paper Microfluidics.

    Science.gov (United States)

    Ainla, Alar; Hamedi, Mahiar M; Güder, Firat; Whitesides, George M

    2017-10-01

    This paper describes electrically-activated fluidic valves that operate based on electrowetting through textiles. The valves are fabricated from electrically conductive, insulated, hydrophobic textiles, but the concept can be extended to other porous materials. When the valve is closed, the liquid cannot pass through the hydrophobic textile. Upon application of a potential (in the range of 100-1000 V) between the textile and the liquid, the valve opens and the liquid penetrates the textile. These valves actuate in less than 1 s, require low energy (≈27 µJ per actuation), and work with a variety of aqueous solutions, including those with low surface tension and those containing bioanalytes. They are bistable in function, and are, in a sense, the electrofluidic analog of thyristors. They can be integrated into paper microfluidic devices to make circuits that are capable of controlling liquid, including autonomous fluidic timers and fluidic logic. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Acoustic-Modal Testing of the Ares I Launch Abort System Attitude Control Motor Valve

    Science.gov (United States)

    Davis, R. Benjamin; Fischbach, Sean R.

    2010-01-01

    The Attitude Control Motor (ACM) is being developed for use in the Launch Abort System (LAS) of NASA's Ares I launch vehicle. The ACM consists of a small solid rocket motor and eight actuated pintle valves that directionally allocate.thrust_- 1t.has-been- predicted-that significant unsteady. pressure.fluctuations.will.exist. inside the-valves during operation. The dominant frequencies of these oscillations correspond to the lowest several acoustic natural frequencies of the individual valves. An acoustic finite element model of the fluid volume inside the valve has been critical to the prediction of these frequencies and their associated mode shapes. This work describes an effort to experimentally validate the acoustic finite model of the valve with an acoustic modal test. The modal test involved instrumenting a flight-like valve with six microphones and then exciting the enclosed air with a loudspeaker. The loudspeaker was configured to deliver broadband noise at relatively high sound pressure levels. The aquired microphone signals were post-processed and compared to results generated from the acoustic finite element model. Initial comparisons between the test data and the model results revealed that additional model refinement was necessary. Specifically, the model was updated to implement a complex impedance boundary condition at the entrance to the valve supply tube. This boundary condition models the frequency-dependent impedance that an acoustic wave will encounter as it reaches the end of the supply tube. Upon invoking this boundary condition, significantly improved agreement between the test data and the model was realized.

  5. Uraemic hyperparathyroidism causes a reversible inflammatory process of aortic valve calcification in rats.

    Science.gov (United States)

    Shuvy, Mony; Abedat, Suzan; Beeri, Ronen; Danenberg, Haim D; Planer, David; Ben-Dov, Iddo Z; Meir, Karen; Sosna, Jacob; Lotan, Chaim

    2008-08-01

    Renal failure is associated with aortic valve calcification (AVC). Our aim was to develop an animal model for exploring the pathophysiology and reversibility of AVC, utilizing rats with diet-induced kidney disease. Sprague-Dawley rats (n = 23) were fed a phosphate-enriched, uraemia-inducing diet for 7 weeks followed by a normal diet for 2 weeks ('diet group'). These rats were compared with normal controls (n = 10) and with uraemic controls fed with phosphate-depleted diet ('low-phosphate group', n = 10). Clinical investigations included serum creatinine, phosphate and parathyroid hormone (PTH) levels, echocardiography, and multislice computed tomography. Pathological examinations of the valves included histological characterization, Von Kossa staining, and antigen and gene expression analyses. Eight diet group rats were further assessed for reversibility of valve calcification following normalization of their kidney function. At 4 weeks, all diet group rats developed renal failure and hyperparathyroidism. At week 9, renal failure resolved with improvement in the hyperparathyroid state. Echocardiography demonstrated valve calcifications only in diet group rats. Tomographic calcium scores were significantly higher in the diet group compared with controls. Von Kossa stain in diet group valves revealed calcium deposits, positive staining for osteopontin, and CD68. Gene expression analyses revealed overexpression of osteoblast genes and nuclear factor kappaB activation. Valve calcification resolved after diet cessation in parallel with normalization of PTH levels. Resolution was associated with down-regulation of inflammation and osteoblastic features. Low-phosphate group rats developed kidney dysfunction similar to that of the diet group but with normal levels of PTH. Calcium scores and histology showed only minimal valve calcification. We developed an animal model for AVC. The process is related to disturbed mineral metabolism. It is associated with inflammation and

  6. Physiological vortices in the sinuses of Valsalva: An in vitro approach for bio-prosthetic valves.

    Science.gov (United States)

    Toninato, Riccardo; Salmon, Jacob; Susin, Francesca Maria; Ducci, Andrea; Burriesci, Gaetano

    2016-09-06

    The physiological flow dynamics within the Valsalva sinuses, in terms of global and local parameters, are still not fully understood. This study attempts to identify the physiological conditions as closely as possible, and to give an explanation of the different and sometime contradictory results in literature. An in vitro approach was implemented for testing porcine bio-prosthetic valves operating within different aortic root configurations. All tests were performed on a pulse duplicator, under physiological pressure and flow conditions. The fluid dynamics established in the various cases were analysed by means of 2D Particle Image Velocimetry, and related with the achieved hydrodynamic performance. Each configuration is associated with substantially different flow dynamics, which significantly affects the valve performance. The configuration most closely replicating healthy native anatomy was characterised by the best hemodynamic performance, and any mismatch in size and position between the valve and the root produced substantial modification of the fluid dynamics downstream of the valve, hindering the hydrodynamic performance of the system. The worst conditions were observed for a configuration characterised by the total absence of the Valsalva sinuses. This study provides an explanation for the different vortical structures described in the literature downstream of bioprosthetic valves, enlightening the experimental complications in valve testing. Most importantly, the results clearly identify the fluid mechanisms promoted by the Valsalva sinuses to enhance the ejection and closing phases, and this study exposes the importance of an optimal integration of the valve and root, to operate as a single system. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. TCT-670 Optimal Transcatheter Heart Valve Sizing in Aortic Valve in Valve Implantation: Insights from the Valve in Valve International Data (VIVID) Registry

    DEFF Research Database (Denmark)

    Alnasser, Sami; Cheema, Asim N; Horlick, Eric

    2016-01-01

    )/true ID x 100. Results: A total of 595 patients (359 for standard size and 236 for oversized group) were included in the analysis. Baseline clinical, hemodynamic and surgical valve parameters were similar in these two groups. Both groups used similar THV devices in each matched comparison. The oversized.......1±8.1mmHg vs. 17.4±8.5mmHg, p=0.002) in comparison to the standard cohort. The oversized group however, had a higher rate of moderate to severe AI (6.9% vs. 2.7%, p=0.001) and second THV requirement (5.5%vs. 2.2%, p=0.04). THV mal-positioning, coronary obstruction and postoperative pacemaker requirement...

  8. Transcatheter pulmonary valve replacement by hybrid approach using a novel polymeric prosthetic heart valve: proof of concept in sheep.

    Science.gov (United States)

    Zhang, Ben; Chen, Xiang; Xu, Tong-yi; Zhang, Zhi-gang; Li, Xin; Han, Lin; Xu, Zhi-yun

    2014-01-01

    Since 2000, transcatheter pulmonary valve replacement has steadily advanced. However, the available prosthetic valves are restricted to bioprosthesis which have defects like poor durability. Polymeric heart valve is thought as a promising alternative to bioprosthesis. In this study, we introduced a novel polymeric transcatheter pulmonary valve and evaluated its feasibility and safety in sheep by a hybrid approach. We designed a novel polymeric trileaflet transcatheter pulmonary valve with a balloon-expandable stent, and the valve leaflets were made of 0.1-mm expanded polytetrafluoroethylene (ePTFE) coated with phosphorylcholine. We chose glutaraldehyde-treated bovine pericardium valves as control. Pulmonary valve stents were implanted in situ by a hybrid transapical approach in 10 healthy sheep (8 for polymeric valve and 2 for bovine pericardium valve), weighing an average of 22.5±2.0 kg. Angiography and cardiac catheter examination were performed after implantation to assess immediate valvular functionality. After 4-week follow-up, angiography, echocardiography, computed tomography, and cardiac catheter examination were used to assess early valvular function. One randomly selected sheep with polymeric valve was euthanized and the explanted valved stent was analyzed macroscopically and microscopically. Implantation was successful in 9 sheep. Angiography at implantation showed all 9 prosthetic valves demonstrated orthotopic position and normal functionality. All 9 sheep survived at 4-week follow-up. Four-week follow-up revealed no evidence of valve stent dislocation or deformation and normal valvular and cardiac functionality. The cardiac catheter examination showed the peak-peak transvalvular pressure gradient of the polymeric valves was 11.9±5.0 mmHg, while that of two bovine pericardium valves were 11 and 17 mmHg. Gross morphology demonstrated good opening and closure characteristics. No thrombus or calcification was seen macroscopically. This design of the

  9. Transseptal transcatheter mitral valve-in-valve: A step by step guide from preprocedural planning to postprocedural care.

    Science.gov (United States)

    Guerrero, Mayra; Salinger, Michael; Pursnani, Amit; Pearson, Paul; Lampert, Mark; Levisay, Justin; Russell, Hyde; Feldman, Ted

    2017-05-30

    Transcatheter mitral valve replacement has been successfully performed with the use of aortic transcatheter heart valves in hundreds of patients worldwide with severe dysfunction of a degenerated mitral bioprosthesis and high surgical risk for repeat operation. The delivery approach in the vast majority of the mitral valve-in-valve procedures has been transapical. Although the transseptal approach may be more technically challenging, it is less invasive and may be preferred by patients. Data from case series and a large international registry suggest that patients treated with transseptal mitral valve-in-valve have faster recovery, more improvement in left ventricular ejection fraction and possibly lower mortality compared with patients treated with transapical approach. A prospective clinical trial, the MITRAL trial (Mitral Implantation of TRAnscatheter vaLves) is evaluating the safety and feasibility of transvenous transseptal mitral valve-in-valve. The experience from this trial has allowed us to improve our procedural approach. In anticipation of a wider adoption of the transseptal approach for mitral valve-in-valve, we describe our current method step-by-step from planning the procedure through postprocedural management. This is an evolving technique that has changed with experience and the transition to newer generation transcatheter heart valve devices. We discuss the use of cardiac computed tomography for planning the procedure including transseptal puncture and valve size selection, provide procedural and technical tips, and discuss postprocedural care. © 2017 Wiley Periodicals, Inc.

  10. Mechanical Designs for Relief Valves for Cryogenic Apparatuses and Installations

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    There are also pressure relief valves with warm seat available on which the set pressure is based on an adjustment of forces by permanent magnets. Pressure vessel rules allows also the choice for an active triggered pressure relief valve (Cont...

  11. Recognizing the Symptoms of Worsening Heart Valve Disease

    Science.gov (United States)

    ... be hard to separate our habits from the mechanics of our hearts, which is one important reason ... About Heart Valves • Heart Valve Problems and Causes • Risks, Signs and Symptoms Introduction Understanding Symptoms Recognizing Symptoms ...

  12. TRINITY heart valve prosthesis: a novel repositionable and retrievable transapical transcatheter aortic valve system.

    Science.gov (United States)

    Hengstenberg, Christian; Condado, Jose; Garcia, David; Martinez, Milka Marin; La Forgia, Giambattista; Ebner, Adrian; Gallo, Santiago; Silva, Enrique; Holzamer, Andreas; Husser, Oliver; Hilker, Michael

    2015-03-01

    Transcatheter aortic valve implantation (TAVI) has become a viable option for selected high-risk patients with severe and symptomatic aortic stenosis. First- and second-generation TAVI devices are either self- or balloon-expandable, and are often not repositionable or not fully retrievable, leading to suboptimal positioning in some cases. This may result in paravalvular regurgitation, AV conduction delay, or compromise of coronary perfusion. A broader application of TAVI requires advances in both valve and delivery systems. Therefore, in order to facilitate accurate positioning, to minimise paravalvular leakage, possibly to reduce the risk of AV conduction delay, and possibly to be able to abort the procedure, a "next-generation" TAVI system has been developed which is repositionable and retrievable, the TRINITY heart valve system. The TRINITY heart valve system was implanted in a first-in-human study using the transapical approach to demonstrate feasibility and procedural success. All endpoints were adjudicated according to VARC definitions at seven and 30 days. The TRINITY heart valve system was implanted in a 74-year-old patient with severe symptomatic aortic valve stenosis. In this case, repositioning of the TRINITY resulted in optimal position without paravalvular leakage and with perfect function. The TRINITY heart valve is a repositionable and retrievable TAVI system. Both the implantation result and short-term clinical and haemodynamic outcome were excellent.

  13. Multi-scale biomechanical remodeling in aging and genetic mutant murine mitral valve leaflets: insights into Marfan syndrome.

    Directory of Open Access Journals (Sweden)

    Russell A Gould

    Full Text Available Mitral valve degeneration is a key component of the pathophysiology of Marfan syndrome. The biomechanical consequences of aging and genetic mutation in mitral valves are poorly understood because of limited tools to study this in mouse models. Our aim was to determine the global biomechanical and local cell-matrix deformation relationships in the aging and Marfan related Fbn1 mutated murine mitral valve. To conduct this investigation, a novel stretching apparatus and gripping method was implemented to directly quantify both global tissue biomechanics and local cellular deformation and matrix fiber realignment in murine mitral valves. Excised mitral valve leaflets from wild-type and Fbn1 mutant mice from 2 weeks to 10 months in age were tested in circumferential orientation under continuous laser optical imaging. Mouse mitral valves stiffen with age, correlating with increases in collagen fraction and matrix fiber alignment. Fbn1 mutation resulted in significantly more compliant valves (modulus 1.34 ± 0.12 vs. 2.51 ± 0.31 MPa, respectively, P<.01 at 4 months, corresponding with an increase in proportion of GAGs and decrease in elastin fraction. Local cellular deformation and fiber alignment change linearly with global tissue stretch, and these slopes become more extreme with aging. In comparison, Fbn1 mutated valves have decoupled cellular deformation and fiber alignment with tissue stretch. Taken together, quantitative understanding of multi-scale murine planar tissue biomechanics is essential for establishing consequences of aging and genetic mutations. Decoupling of local cell-matrix deformation kinematics with global tissue stretch may be an important mechanism of normal and pathological biomechanical remodeling in valves.

  14. Determinants of image quality of rotational angiography for on-line assessment of frame geometry after transcatheter aortic valve implantation.

    Science.gov (United States)

    Rodríguez-Olivares, Ramón; El Faquir, Nahid; Rahhab, Zouhair; Maugenest, Anne-Marie; Van Mieghem, Nicolas M; Schultz, Carl; Lauritsch, Guenter; de Jaegere, Peter P T

    2016-07-01

    To study the determinants of image quality of rotational angiography using dedicated research prototype software for motion compensation without rapid ventricular pacing after the implantation of four commercially available catheter-based valves. Prospective observational study including 179 consecutive patients who underwent transcatheter aortic valve implantation (TAVI) with either the Medtronic CoreValve (MCS), Edward-SAPIEN Valve (ESV), Boston Sadra Lotus (BSL) or Saint-Jude Portico Valve (SJP) in whom rotational angiography (R-angio) with motion compensation 3D image reconstruction was performed. Image quality was evaluated from grade 1 (excellent image quality) to grade 5 (strongly degraded). Distinction was made between good (grades 1, 2) and poor image quality (grades 3-5). Clinical (gender, body mass index, Agatston score, heart rate and rhythm, artifacts), procedural (valve type) and technical variables (isocentricity) were related with the image quality assessment. Image quality was good in 128 (72 %) and poor in 51 (28 %) patients. By univariable analysis only valve type (BSL) and the presence of an artefact negatively affected image quality. By multivariate analysis (in which BMI was forced into the model) BSL valve (Odds 3.5, 95 % CI [1.3-9.6], p = 0.02), presence of an artifact (Odds 2.5, 95 % CI [1.2-5.4], p = 0.02) and BMI (Odds 1.1, 95 % CI [1.0-1.2], p = 0.04) were independent predictors of poor image quality. Rotational angiography with motion compensation 3D image reconstruction using a dedicated research prototype software offers good image quality for the evaluation of frame geometry after TAVI in the majority of patients. Valve type, presence of artifacts and higher BMI negatively affect image quality.

  15. Stent and leaflet stresses in a 26-mm first-generation balloon-expandable transcatheter aortic valve.

    Science.gov (United States)

    Xuan, Yue; Krishnan, Kapil; Ye, Jian; Dvir, Danny; Guccione, Julius M; Ge, Liang; Tseng, Elaine E

    2017-05-01

    Transcatheter aortic valve replacement is established therapy for high-risk and inoperable patients with severe aortic stenosis, but questions remain regarding long-term durability. Valve design influences durability. Increased leaflet stresses in surgical bioprostheses have been correlated with degeneration; however, transcatheter valve leaflet stresses are unknown. From 2007 to 2014, a majority of US patients received first-generation balloon-expandable transcatheter valves. Our goal was to determine stent and leaflet stresses in this valve design using finite element analyses. A 26-mm Sapien Transcatheter Heart Valve (Edwards Lifesciences, Inc, Irvine, Calif) underwent high-resolution microcomputed tomography scanning to develop precise 3-dimensional geometry of the leaflets, the stent, and the polyethylene terephthalate elements. The stent was modeled using 3-dimensional elements and the leaflets were modeled using shell elements. Stent material properties were based on stainless steel, whereas those for leaflets were obtained from surgical bioprostheses. Noncylindrical Sapien valve geometry was also simulated. Pressure loading to 80 mm Hg and 120 mm Hg was performed using ABAQUS finite element software (Dassault Systèmes, Waltham, Mass). At 80 mm Hg, maximum principal stresses on Sapien leaflets were 1.31 megaspascals (MPa). Peak leaflet stress was observed at commissural tips where leaflets connected to the stent. Maximum principal stresses for the stent were 188.91 MPa and located at stent tips where leaflet commissures were attached. Noncylindrical geometry increased peak principal leaflet stresses by 16%. Using exact geometry from high-resolution scans, the 26-mm Sapien Transcatheter Heart Valve showed that peak stresses for both stent and leaflets were present at commissural tips where leaflets were attached. These regions would be prone to leaflet degeneration. Understanding stresses in first-generation transcatheter valves allows comparison to

  16. Compact UHV valve with field replaceable windows

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, E.D. (Brookhaven National Lab., Upton, NY (United States)); Freeman, J. (VAT, Inc., Woburn, MA (United States)); Powell, F. (Luxel, Inc., Friday Harbor, WA (United States))

    1991-01-01

    There are many applications in synchrotron radiation research where window valves can be usefully employed. Examples include gas cells for monochromator calibration, filters for high order light rejection, and as vacuum isolation elements between machine and experimental vacua. Often these devices are fairly expensive, and have only fixed (ie non-removable) windows. The development of a new type of seal technology by VAT for their series 01 valves provides a gate surface which is free from obstructions due to internal mechanical elements. This feature allows a threaded recess to be machined into the gate to receive a removable window frame which can carry standard size Luxel thin film windows. The combination of these features results in a DN 40 (2.75in. conflat flange) valve which provides a clear aperture of 21mm diameter for the window material. 8 refs., 2 figs.

  17. Cardiac Rehabilitation After Heart Valve Surgery

    DEFF Research Database (Denmark)

    Pollmann, Agathe Gerwina Elena; Frederiksen, Marianne; Prescott, Eva

    2017-01-01

    PURPOSE: Evidence of the effect of cardiac rehabilitation (CR) after heart valve surgery is scarce, but nevertheless CR is recommended for this group of patients. Therefore, this study assessed the effect of CR on exercise capacity, cardiovascular risk factors, and long-term mortality and morbidity......, as well as predictors for enrolment in or failing to complete CR. METHODS: A review of medical records identified 250 patients who underwent heart valve surgery between January 2009 and August 2013. Of these, 211 patients eligible for CR were identified. Effect of CR was assessed by peak oxygen uptake.......58-15.06). CONCLUSIONS: CR after heart valve surgery improved exercise capacity and was associated with reduced morbidity. Elderly and ethnic minorities were less likely to attend or complete CR and deserve special attention....

  18. Piezogenic pedal papules with mitral valve prolapse

    Directory of Open Access Journals (Sweden)

    Cihan Altin

    2016-01-01

    Full Text Available Piezogenic pedal papules (PPP are herniations of subcutaneous adipose tissue into the dermis. PPP are skin-colored to yellowish papules and nodules on lateral surfaces of feet that typically become apparent when the patient stands flat on his/her feet. Some connective tissue diseases and syndromes have been reported in association with PPP. Mitral valve prolapse (MVP is a myxomatous degeneration of the mitral valve, characterized by the displacement of an abnormally thickened mitral valve leaflet into the left atrium during systole. MVP may be isolated or part of a heritable connective tissue disorder. PPP, which is generally considered as an isolated lesion, might be also a predictor of some cardiac diseases associated with connective tissue abnormalities such as MVP. A detailed systemic investigation including cardiac examination should be done in patients with PPP. Since in the literature, there are no case reports of association of PPP with MVP, we report these cases.

  19. Three-dimensional echocardiography in valve disease

    Directory of Open Access Journals (Sweden)

    Cesare Fiorentini

    2009-08-01

    Full Text Available This review covers the role of three-dimensional (3D echocardiography in the diagnosis of heart valve disease. Several factors have contributed to the evolution of this technique, which is currently a simple and routine method: rapid evolution in probe and computer technologies, demonstration that 3D data sets allowed more complete and accurate evaluation of cardiac structures, emerging clinical experience indicating the strong potential particularly in valve diseases, volume and function of the two ventricle measurements and several other fields. This report will review current and future applications of 3D echocardiography in mitral, aortic and tricuspid valve diseases underlying both qualitative (morphologic and quantitative advantages of this technique. (Heart International 2007; 3: 35-41

  20. Magneto-Seebeck effect in spin valves

    Science.gov (United States)

    Zhang, X. M.; Wan, C. H.; Wu, H.; Tang, P.; Yuan, Z. H.; Zhang, Q. T.; Zhang, X.; Tao, B. S.; Fang, C.; Han, X. F.

    2017-10-01

    The magneto-Seebeck (MS) effect, which is also called magneto-thermo-power, was observed in Co/Cu/Co and NiFe/Cu/Co spin valves. Their Seebeck coefficients in the parallel state were larger than those in the antiparallel state, and the MS ratio defined as (SAP -SP)/SP could reach -9% in our case. The MS effect originated not only from trivial giant magnetoresistance but also from spin current generated due to spin-polarized thermoelectric conductivity of ferromagnetic materials and subsequent modulation of the spin current by different spin configurations in spin valves. A simple Mott two-channel model reproduced a -11% MS effect for the Co/Cu/Co spin valves, qualitatively consistent with our observations. The MS effect could be applied for simultaneously sensing the temperature gradient and the magnetic field and also be possibly applied to determine spin polarization of thermoelectric conductivity and the Seebeck coefficient of ferromagnetic thin films.