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Sample records for human carotid bifurcation

  1. Targeted particle tracking in computational models of human carotid bifurcations.

    Science.gov (United States)

    Marshall, Ian

    2011-12-01

    A significant and largely unsolved problem of computational fluid dynamics (CFD) simulation of flow in anatomically relevant geometries is that very few calculated pathlines pass through regions of complex flow. This in turn limits the ability of CFD-based simulations of imaging techniques (such as MRI) to correctly predict in vivo performance. In this work, I present two methods designed to overcome this filling problem, firstly, by releasing additional particles from areas of the flow inlet that lead directly to the complex flow region ("preferential seeding") and, secondly, by tracking particles both "downstream" and "upstream" from seed points within the complex flow region itself. I use the human carotid bifurcation as an example of complex blood flow that is of great clinical interest. Both idealized and healthy volunteer geometries are investigated. With uniform seeding in the inlet plane (in the common carotid artery (CCA)) of an idealized bifurcation geometry, approximately half the particles passed through the internal carotid artery (ICA) and half through the external carotid artery. However, of those particles entering the ICA, only 16% passed directly through the carotid bulb region. Preferential seeding from selected regions of the CCA was able to increase this figure to 47%. In the second method, seeding of particles within the carotid bulb region itself led to a very high proportion (97%) of pathlines running from CCA to ICA. Seeding of particles in the bulb plane of three healthy volunteer carotid bifurcation geometries led to much better filling of the bulb regions than by particles seeded at the inlet alone. In all cases, visualization of the origin and behavior of recirculating particles led to useful insights into the complex flow patterns. Both seeding methods produced significant improvements in filling the carotid bulb region with particle tracks compared with uniform seeding at the inlet and led to an improved understanding of the complex

  2. Reproducibility study of 3D geometrical reconstruction of the human carotid bifurcation from magnetic resonance images.

    Science.gov (United States)

    Long, Q; Ariff, B; Zhao, S Z; Thom, S A; Hughes, A D; Xu, X Y

    2003-04-01

    The combined magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) modeling approach is playing an increasingly important role in advancing our understanding of the relationship between hemodynamics and arterial disease. Nevertheless, such a modeling approach involves a number of uncertainties associated with various stages of the process. The present study is concerned with the reproducibility of geometry reconstruction, one of the most crucial steps in the modeling process. The reproducibility test was conducted on the right carotid bifurcation of eight normal human subjects, each of whom were scanned twice using the same MR protocol with an in-plane resolution of 0.625 mm. Models constructed from different scans of the same subject were compared and assessed using four quantitative measures: centerline distance, cross-sectional area, contour shape factors, and mean radius difference. The difference in the maximum carotid bulb area between the two scans was found to be impact of geometrical differences on CFD-predicted flow patterns and wall shear stress (WSS) will be investigated and discussed in a separate paper. Copyright 2003 Wiley-Liss, Inc.

  3. [Intracranial carotid artery bifurcation aneurysms].

    Science.gov (United States)

    Vega-Basulto, S D; Montejo-Montejo, J

    Intracranial carotid artery bifurcation aneurysms are infrequent but its clinical behavior, high risk of bleeding and complex anatomic relationships of the sac permit to consider these lesions as a challenge cases. 497 patients harboring intracranial aneurysms were operated on at Manuel Ascunce Domenech Hospital, Camagüey, Cuba between January 1982 to august 2001. We utilized microsurgical procedures, optical magnification, specialized neuroanesthesia and Intensive Care Unit postoperatory following. All patients were evaluated clinically with World Federation Neurological Surgeon Scale and Glasgow Outcome Scale. There were 16 patients with intracranial carotid artery bifurcation aneurysms (3.2 %). 12 patients were under 40 years and 50% were between 16 and 30 years old. All patients present intracranial bleeding. There was 87.5% of total or partial recuperation. There was one death only. Postoperative deficit were observed at 44% but 31% disappeared three month later. Intracranial carotid artery bifurcation aneurysms are complex anatomoclinical lesions. Clinically, we observed high tendency to bleed and multiplicity. Anatomically, these sacs have complex arterial relationship that difficult dissection and clipping. They have frequent postoperative morbidity. Multiple or bilateral aneurysmal sacs will be clipped by one surgical procedure.

  4. Wall shear stress evolution in carotid artery bifurcation

    Science.gov (United States)

    Bernad, S. I.; Bosioc, A. I.; Totorean, A. F.; Petre, I.; Bernad, E. S.

    2017-07-01

    The steady flow in an anatomically realistic human carotid bifurcation was simulated numerically. Main parameters such as wall shear stress (WSS), velocity profiles and pressure distributions are investigated in the carotid artery, namely in bifurcation and sinusoidal enlargement regions. Flow in the carotid sinus is dominated by a single secondary vortex motion accompanied by a strong helical flow. This type of flow is induced primarily by the curvature and asymmetry of the in vivo geometry. Low wall shear stress concentration occurs at both the anterior and posterior aspects of the proximal internal bulb.

  5. Simple classification of carotid bifurcation: is it possible to predict twisted carotid artery during carotid endarterectomy?

    Science.gov (United States)

    Kamide, Tomoya; Nomura, Motohiro; Tamase, Akira; Mori, Kentaro; Seki, Shunsuke; Kitamura, Yoshihisa; Nakada, Mitsutoshi

    2016-12-01

    The internal carotid artery (ICA) usually runs posterolaterally to the external carotid artery (ECA), but occasionally we encounter the twisted carotid bifurcation, a variant in which the ICA courses medially to the ECA during carotid endarterectomy (CEA). Prediction of this anomaly in the preoperative evaluation is mandatory, although descriptions in the literature are limited. We reviewed the clinical features of patients who underwent CEA and analyzed preoperative cerebral angiography, especially the anteroposterior (AP) view to determine whether it could be a predictive modality. In 58 consecutive CEA cases, we simply classified them into three groups; type 1 (the ICA runs laterally and the ECA runs medially), type 2 (the ICA and ECA run to overlap each other), and type 3 (the ICA runs medially and the ECA runs laterally), based on the findings of AP view of cerebral angiography. We compared the clinical features and intraoperative findings of these groups. Of 58 cases, types 1-3 were 24, 30, and four cases, respectively. Twisted carotid bifurcations were recognized in seven cases (12.4 %), including three cases in type 2 and four in type 3, and all twisted cases were found on the right side. Twisted carotids and right-sided lesion were significantly frequent in type 3, but no statistical differences of coexisting diseases were recognized among the three groups. CEAs of twisted carotid bifurcations were performed successfully with correction of the carotid position in three and as it was in four cases. Twisted carotid bifurcations were observed during operation in 10 % in type 2 and 100 % in type 3. CEA of twisted carotid bifurcations can be performed safely with or without correction of the carotid position. AP view of cerebral angiography could be useful for preoperative evaluation.

  6. Percutaneous transluminal angioplasty and stenting for carotid bifurcation stenosis

    NARCIS (Netherlands)

    Vos, J.A.

    2009-01-01

    Carotid Endartectomy (CEA) has been proven to benefit patients with carotid bifurcation stenosis. For patients unfit for this therapy an alternative has been developed, namely Carotid Angioplasty and Stenting (CAS). No anesthesia or neck dissection is necessary in this procedure. In this thesis

  7. Anatomical Considerations on Surgical Anatomy of the Carotid Bifurcation

    Directory of Open Access Journals (Sweden)

    Adamantios Michalinos

    2016-01-01

    Full Text Available Surgical anatomy of carotid bifurcation is of unique importance for numerous medical specialties. Despite extensive research, many aspects such as precise height of carotid bifurcation, micrometric values of carotid arteries and their branches as their diameter, length, and degree of tortuosity, and variations of proximal external carotid artery branches are undetermined. Furthermore carotid bifurcation is involved in many pathologic processes, atheromatous disease being the commonest. Carotid atheromatous disease is a major predisposing factor for disabling and possibly fatal strokes with geometry of carotid bifurcation playing an important role in its natural history. Consequently detailed knowledge of various anatomic parameters is of paramount importance not only for understanding of the disease but also for design of surgical treatment, especially selection between carotid endarterectomy and carotid stenting. Carotid bifurcation paragangliomas constitute unique tumors with diagnostic accuracy, treatment design, and success of operative intervention dependent on precise knowledge of anatomy. Considering those, it becomes clear that selection and application of proper surgical therapy should consider anatomical details. Further research might ameliorate available treatment options or even lead to innovative ones.

  8. Race-ethnic variation in carotid bifurcation geometry.

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    Koch, Sebastian; Nelson, Donoffa; Rundek, Tatjana; Mandrekar, Jay; Rabinstein, Alejandro

    2009-01-01

    Disturbances in local blood flow influenced by arterial geometry contribute to atherogenesis. Carotid bifurcation hemodynamics depend on the relative sizes of the common carotid artery (CCA), internal carotid artery (ICA), and external carotid artery (ECA), which vary considerably among individuals. The prevalence of carotid bifurcation atherosclerosis differs among race-ethnic groups and is generally lower in African Americans despite a more adverse vascular risk factor profile. We here examine whether there are race-ethnic differences in carotid bifurcation anatomy. The diameters of the CCA, carotid bulb, ICA, and ECA were measured from consecutive cerebral angiograms of African American, white, and Caribbean Hispanic patients. The bulb/CCA, ICA/CCA, ECA/CCA, ECA/ICA, and total cross-sectional outflow/inflow ratio ([ICA(2) + ECA(2)]/CCA(2)) were calculated. The final analysis included 272 bifurcations of which 103 were among white, 87 Hispanic, and 82 African American patients. The mean age of the population was 59.8 +/- 15.8 years and 148 (54.4%) were men. African Americans had a lower ICA/CCA ratio (P ECA ratio (P ECA/CCA ratio (P groups. We found significant differences in the relative sizes of the ICA, ECA, and CCA among race-ethnic groups. African Americans had a proportionally smaller ICA and larger ECA in comparison with whites and Caribbean Hispanics.

  9. Increased Vessel Depiction of the Carotid Bifurcation with a Specialized 16-Channel Phased Array Coil at 3T

    Science.gov (United States)

    Tate, Quinn; Kim, Seong-Eun; Treiman, Gerald; Parker, Dennis L.; Hadley, J. Rock

    2012-01-01

    The purpose of this work was to design and construct a multi-channel receive-only RF coil for 3 Tesla magnetic resonance imaging of the human carotid artery and bifurcation with optimized signal to noise ratio in the carotid vessels along the full extent of the neck. A neck phantom designed to match the anatomy of a subject with a neck representing the body habitus often seen in subjects with carotid arterial disease, was constructed. Sixteen circular coil elements were arranged on a semi-rigid fiberglass former that closely fit the shape of the phantom, resulting in a 16-channel bilateral phased array coil. Comparisons were made between this coil and a typical 4-channel carotid coil in a study of 10 carotid vessels in 5 healthy volunteers. The 16-channel carotid coil showed a 73% average improvement in signal to noise ratio (SNR) at the carotid bifurcation. This coil also maintained an SNR greater than the peak SNR of the 4-channel coil over a vessel length of 10 cm. The resulting increase in SNR improved vessel depiction of the carotid arteries over an extended field of view, and demonstrated better image quality for higher parallel imaging reduction factors compared to the 4-channel coil. PMID:22777692

  10. Prediction of fibre architecture and adaptation in diseased carotid bifurcations.

    LENUS (Irish Health Repository)

    Creane, Arthur

    2011-12-01

    Many studies have used patient-specific finite element models to estimate the stress environment in atherosclerotic plaques, attempting to correlate the magnitude of stress to plaque vulnerability. In complex geometries, few studies have incorporated the anisotropic material response of arterial tissue. This paper presents a fibre remodelling algorithm to predict the fibre architecture, and thus anisotropic material response in four patient-specific models of the carotid bifurcation. The change in fibre architecture during disease progression and its affect on the stress environment in the plaque were predicted. The mean fibre directions were assumed to lie at an angle between the two positive principal strain directions. The angle and the degree of dispersion were assumed to depend on the ratio of principal strain values. Results were compared with experimental observations and other numerical studies. In non-branching regions of each model, the typical double helix arterial fibre pattern was predicted while at the bifurcation and in regions of plaque burden, more complex fibre architectures were found. The predicted change in fibre architecture in the arterial tissue during plaque progression was found to alter the stress environment in the plaque. This suggests that the specimen-specific anisotropic response of the tissue should be taken into account to accurately predict stresses in the plaque. Since determination of the fibre architecture in vivo is a difficult task, the system presented here provides a useful method of estimating the fibre architecture in complex arterial geometries.

  11. Denervation of carotid baro- and chemoreceptors in humans

    NARCIS (Netherlands)

    Timmers, H.J.L.M.

    2004-01-01

    Carotid baro- and chemoreceptors play an important role in blood pressure and blood gas homeostasis. Inadvertent denervation of these receptors in humans has been reported following surgery and radiotherapy in the area of the carotid bifurcation. The resulting syndrome of baroreflex failure is

  12. Walled Carotid Bifurcation Phantoms for Imaging Investigations of Vessel Wall Motion and Blood Flow Dynamics.

    Science.gov (United States)

    Chee, Adrian J Y; Ho, Chung Kit; Yiu, Billy Y S; Yu, Alfred C H

    2016-07-18

    As a major application domain of vascular ultrasound, the carotid artery has long been the subject of anthropomorphic phantom design. It is nevertheless not trivial to develop walled carotid phantoms that are compatible for use in integrative imaging of carotid wall motion and flow dynamics. In this paper, we present a novel phantom design protocol that can enable efficient fabrication of walled carotid bifurcation phantoms with: (i) high acoustic compatibility, (ii) artery-like vessel elasticity, and (iii) stenotic narrowing feature. Our protocol first involved direct fabrication of the vessel core and an outer mold using computer-aided design tools and 3-D printing technology; these built parts were then used to construct an elastic vessel tube through investment casting of a polyvinyl alcohol containing mixture, and an agar-gelatin tissue mimicking slab was formed around the vessel tube. For demonstration, we applied our protocol to develop a set of healthy and stenosed (25%, 50%, 75%) carotid bifurcation phantoms. Plane wave imaging experiments were performed on these phantoms using an ultrasound scanner with channel-level configurability. Results show that the wall motion dynamics of our phantoms agreed with pulse wave propagation in an elastic vessel (pulse wave velocity of 4.67±0.71 m/s measured at the common carotid artery), and their flow dynamics matched the expected ones in healthy and stenosed bifurcation (recirculation and flow jet formation observed). Integrative imaging of vessel wall motion and blood flow dynamics in our phantoms was also demonstrated, from which we observed fluid-structure interaction differences between healthy and diseased bifurcation phantoms. These findings show that the walled bifurcation phantoms developed with our new protocol are useful in vascular imaging studies that individually or jointly assess wall motion and flow dynamics.

  13. Volumetric assessment of the carotid bifurcation: an alternative concept to stenosis grading.

    Science.gov (United States)

    Miralles, Manuel; Arrébola, Manel; Bruguer, Sara; Lago, Aida; Lara, Raúl

    2015-04-01

    To design a volumetric method for the assessment of carotid atheromatosis (CA) based on computed tomography (CT) angiography and three-dimensional (3D) reconstructions; to analyze the accuracy and optimal threshold values to differentiate between equivalent degrees of severity by duplex scanning and CT angiography (two-dimensional maximum intensity projection [2D MIP]; internal carotid artery stenosis [ICS] 50%); and to assess the method's suitability to detect progression of CA. suitability and accuracy of a new diagnostic method. 90 carotid bifurcations (45 patients) were assessed with duplex scanning and CT angiography, and reevaluated after 12 ± 2 months follow-up. Determinations: Assessment of internal carotid artery (ICA) stenosis degree with duplex scanning and 2D MIP CT angiography projections. Volumetric assessment of carotid bifurcation by CT angiography (contrast volume [mm(3)] and density [Hounsfield units, H.U.] between 2-cm below and 1-cm above the anatomic bifurcation of the carotid artery [BifV], and its ratio with 1-cm segment of the common carotid artery [CCV]). descriptive statistics; intraobserver and interobserver agreement (Bland-Altman plot and intraclass correlation coefficient [ICC], accuracy of 3D volumetry and duplex scanning as referred to MIP 2D CT angiography as gold standard: sensitivity (Sens), specificity (Sp), kappa index, and receiver operating characteristic curves (ROCs). Estimation of MIP 2D images (CT angiography) confirmed the findings of duplex scanning in 23 of 30 ICS 50% (Sens, 0.91; Sp, 0.77% kappa = 0.68). Three-dimensional volumetric assessment of carotid bifurcation showed an intraobserver and interobserver agreement with an ICC of 0.96 (95% confidence interval [CI], 0.904-0.985) and 0.94 (95% CI, 0.822-0.977), respectively. The BifV-to-CCV ratio was 5.2 ± 1.8 in the ICS 50% group (P = 0.001). The optimal cutoff point of the BifV-to-CCV relationship was identified from the ROC curve in 4.1 (Sens, 0.75; Sp, 0

  14. Synchronous Carotid Bifurcation Endarterectomy and Retrograde Kissing Stenting of the Innominate and Left Common Carotid Artery in a Patient with a Bovine Aortic Arch

    OpenAIRE

    Alessandro Robaldo; Guido Carignano; Alberto Balderi; Claudio Novali

    2017-01-01

    Management of the symptomatic multiple stenosis of supra-aortic vessels (MSSVs) in a “bovine” aortic arch (BAA) configuration is infrequently reported. The optimal treatment choice remains debatable. A successful hybrid treatment for a proximal critical stenosis of the innominate and left common carotid artery was performed in a high-risk patient with a tandem symptomatic lesion in the right carotid bifurcation and a concentric vulnerable plaque in the bovine trunk. This case supports the fea...

  15. Machine Learning Approach for Predicting Wall Shear Distribution for Abdominal Aortic Aneurysm and Carotid Bifurcation Models.

    Science.gov (United States)

    Jordanski, Milos; Radovic, Milos; Milosevic, Zarko; Filipovic, Nenad; Obradovic, Zoran

    2016-12-14

    Computer simulations based on the finite element method (FEM) represent powerful tools for modeling blood flow through arteries. However, due to its computational complexity, this approach may be inappropriate when results are needed quickly. In order to reduce computational time, in this paper we proposed an alternative machine learning based approach for calculation of wall shear stress (WSS) distribution, which may play an important role in mechanisms related to initiation and development of atherosclerosis. In order to capture relationships between geometric parameters, blood density, dynamic viscosity and velocity and WSS distribution of geometrically parameterized abdominal aortic aneurysm (AAA) and carotid bifurcation models, we proposed multivariate linear regression (MLR), multilayer perceptron neural network (MLP) and gaussian conditional random fields (GCRF). Results obtained in this paper show that machine learning approaches can successfully predict WSS distribution at different cardiac cycle time points. Even though all proposed methods showed high potential for WSS prediction, GCRF achieved the highest coefficient of determination (0.930 to 0.948 for AAA model and 0.946 to 0.954 for carotid bifurcation model) demonstrating benefits of accounting for spatial correlation. The proposed approach can be used as an alternative method for real time calculation of wall shear stress distribution.

  16. Asymmetric pulsation of rat carotid artery bifurcation in three-dimension observed by ultrasound imaging.

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    Jin, Changzhu; Nam, Kweon-Ho; Paeng, Dong-Guk

    2016-10-01

    The arterial structure cyclically fluctuates in three-dimensions (3-D) caused by pulsatile blood flow. The evaluation of arterial wall motion and hemodynamics contributes to early diagnosis of carotid atherosclerosis. Ultrasound is one of the most appropriate imaging modalities to evaluate arterial wall motion in real time. Although many previous studies have discussed the mechanical properties of the carotid artery bifurcation (CAB) from the two-dimensional (2-D) view, the spatio-temporal variation of carotid artery geometry in 3-D has not yet been investigated in detail. In this study, the 3-D data set of CAB from rats was acquired using a high spatio-temporal resolution ultrasound imaging system with a 40 MHz probe using mechanical sector scanning. A total of 31 slices of cross-section images were stored and a spoke scan algorithm was implemented to radially scan the lumen area in polar coordinates based on a pre-tracked seed point. The boundary of the arterial lumen was segmented using intensity-threshold-based boundary detection and fitted by polynomial regression. Two operators, who were trained with the same protocol to minimize inter- and intra-operator variability, manually segmented the lumen boundary on systolic and diastolic phase from the gray-scale images. Finally, the 3-D lumen geometries of CAB during one cardiac cycle were constructed based on the segmented lumen boundaries. From this constructed 3-D geometry, we observed that the CAB geometry favorably expanded to the anterior/posterior direction, parallel to the sagittal plane; and the manually segmented geometry also confirmed the asymmetrical change in bifurcation geometry. This is the first study on visualization and quantification on the asymmetrical variation of the CAB geometry of a rat in 3-D during a whole cardiac cycle. This finding may be useful in understanding hemodynamic etiology of various cardiovascular diseases such as arterial stenosis and its complications, and also provides

  17. High-frame-rate Imaging of a Carotid Bifurcation using a Low-complexity Velocity Estimation Approach

    DEFF Research Database (Denmark)

    di Ianni, Tommaso; Villagómez Hoyos, Carlos Armando; Ewertsen, Caroline

    2017-01-01

    In this paper, a 2-D vector flow imaging (VFI) method developed by combining synthetic aperture sequential beamforming and directional transverse oscillation is used to image a carotid bifurcation. Ninety-six beamformed lines are sent from the probe to the host system for each VFI frame, enabling...

  18. Preliminary study of hemodynamic distribution in patient-specific stenotic carotid bifurcation by image-based computational fluid dynamics.

    Science.gov (United States)

    Xue, Y-J; Gao, P-Y; Duan, Q; Lin, Y; Dai, C-B

    2008-06-01

    Regions prone to atherosclerosis, such as bends and bifurcations, tend to exhibit a certain degree of non-planarity or curvature, and these geometric features are known to strongly influence local flow patterns. Recently, computational fluid dynamics (CFD) has been used as a means of enhancing understanding of the mechanisms involved in atherosclerotic plaque formation and development. To analyze flow patterns and hemodynamic distribution in stenotic carotid bifurcation in vivo by combining CFD with magnetic resonance angiography (MRA). Twenty-one patients with carotid atherosclerosis proved by digital subtraction angiography (DSA) and/or Doppler ultrasound underwent contrast-enhanced MR angiography of the carotid bifurcation by a 3.0T MR scanner. Hemodynamic variables and flow patterns of the carotid bifurcation were calculated and visualized by combining vascular imaging postprocessing with CFD. In mild stenotic cases, there was much more streamlined flow in the bulbs, with reduced or disappeared areas of weakly turbulent flow. Also, the corresponding areas of low wall shear stress (WSS) were reduced or even disappeared. As the extent of stenosis increased, stronger blood jets formed at the portion of narrowing, and more prominent eddy flows and slow back flows were noted in the lee of the stenosis. Regions of elevated WSS were predicted at the portion of stenosis and in the path of the downstream jet. Areas of low WSS were predicted on the leeward side of the stenosis, corresponding with the location of slowly turbulent flows. CFD combined with MRA can simulate flow patterns and calculate hemodynamic variables in stenotic carotid bifurcations as well as normal ones. It provides a new method to investigate the relationship of vascular geometry and flow condition with atherosclerotic pathological changes.

  19. A remodelling metric for angular fibre distributions and its application to diseased carotid bifurcations.

    LENUS (Irish Health Repository)

    Creane, Arthur

    2012-07-01

    Many soft biological tissues contain collagen fibres, which act as major load bearing constituents. The orientation and the dispersion of these fibres influence the macroscopic mechanical properties of the tissue and are therefore of importance in several areas of research including constitutive model development, tissue engineering and mechanobiology. Qualitative comparisons between these fibre architectures can be made using vector plots of mean orientations and contour plots of fibre dispersion but quantitative comparison cannot be achieved using these methods. We propose a \\'remodelling metric\\' between two angular fibre distributions, which represents the mean rotational effort required to transform one into the other. It is an adaptation of the earth mover\\'s distance, a similarity measure between two histograms\\/signatures used in image analysis, which represents the minimal cost of transforming one distribution into the other by moving distribution mass around. In this paper, its utility is demonstrated by considering the change in fibre architecture during a period of plaque growth in finite element models of the carotid bifurcation. The fibre architecture is predicted using a strain-based remodelling algorithm. We investigate the remodelling metric\\'s potential as a clinical indicator of plaque vulnerability by comparing results between symptomatic and asymptomatic carotid bifurcations. Fibre remodelling was found to occur at regions of plaque burden. As plaque thickness increased, so did the remodelling metric. A measure of the total predicted fibre remodelling during plaque growth, TRM, was found to be higher in the symptomatic group than in the asymptomatic group. Furthermore, a measure of the total fibre remodelling per plaque size, TRM\\/TPB, was found to be significantly higher in the symptomatic vessels. The remodelling metric may prove to be a useful tool in other soft tissues and engineered scaffolds where fibre adaptation is also present.

  20. Complete transposition of carotid bifurcation: can it be an additional risk factor of injury to the cranial nerves during carotid endarterectomy?

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    Marcucci, Giustino; Accrocca, Federico; Gabrielli, Roberto; Antonelli, Roberto; Giordano, Alessandro G; De Vivo, Gennaro; Siani, Andrea

    2011-11-01

    The internal carotid artery (ICA) usually, lies posterolaterally to the external carotid artery (ECA). Sometimes a complete carotid transposition can occur, with the ECA in a lateral position and the ICA on the medial side can occur. Our study evaluated the significance and impact that this anomaly may have on cranial nerve injuries. From January 2008 to November 2010, 296 patients underwent 360 consecutive primary carotid endarterectomy (CEA) procedures. During carotid isolation, we detected an unexpected lateral position of the ECA in 11 cases (3.6%). χ(2) analysis and the Student's t-test were used to compare the incidence of cranial nerve injuries between the 11 patients with the lateral ECA who underwent CEA (group A) and 11 randomized patients with a normal bifurcation (group B). Statistical significance was inferred at χ(2)>3.84 and Pgroups A and B (18.1%, 2/11 in group A vs. 0%, 0/11 in group B; χ(2)>3.84; PECA and ICA is needed to perform CEA, but superior laryngeal nerve injury can occur despite the use of a safe and meticulous surgical technique.

  1. Effect of calcification on the mechanical stability of plaque based on a three-dimensional carotid bifurcation model

    Directory of Open Access Journals (Sweden)

    Wong Kelvin KL

    2012-02-01

    Full Text Available Abstract Background This study characterizes the distribution and components of plaque structure by presenting a three-dimensional blood-vessel modelling with the aim of determining mechanical properties due to the effect of lipid core and calcification within a plaque. Numerical simulation has been used to answer how cap thickness and calcium distribution in lipids influence the biomechanical stress on the plaque. Method Modelling atherosclerotic plaque based on structural analysis confirms the rationale for plaque mechanical examination and the feasibility of our simulation model. Meaningful validation of predictions from modelled atherosclerotic plaque model typically requires examination of bona fide atherosclerotic lesions. To analyze a more accurate plaque rupture, fluid-structure interaction is applied to three-dimensional blood-vessel carotid bifurcation modelling. A patient-specific pressure variation is applied onto the plaque to influence its vulnerability. Results Modelling of the human atherosclerotic artery with varying degrees of lipid core elasticity, fibrous cap thickness and calcification gap, which is defined as the distance between the fibrous cap and calcification agglomerate, form the basis of our rupture analysis. Finite element analysis shows that the calcification gap should be conservatively smaller than its threshold to maintain plaque stability. The results add new mechanistic insights and methodologically sound data to investigate plaque rupture mechanics. Conclusion Structural analysis using a three-dimensional calcified model represents a more realistic simulation of late-stage atherosclerotic plaque. We also demonstrate that increases of calcium content that is coupled with a decrease in lipid core volume can stabilize plaque structurally.

  2. Intramural location and size of arterial calcification are associated with stenosis at carotid bifurcation

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    Yamada, Shigeki, E-mail: shigekiyamada3@gmail.com [Department of Neurosurgery and Stroke Center, Rakuwakai Otowa Hospital, Otowachinji-cho 2, Yamashina-ku, Kyoto 607-8602 (Japan); Department of Neurosurgery, Hamamatsu Rosai Hospital, 25 Shogen-cho, Higashi-ku, Hamamatsu city, Shizuoka 430-8525 (Japan); Interfaculty Initiative in Information Studies/Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Oshima, Marie, E-mail: marie@iis.u-tokyo.ac.jp [Interfaculty Initiative in Information Studies/Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Watanabe, Yoshihiko, E-mail: ynabe@magic.odn.ne.jp [Department of Neurosurgery, Hamamatsu Rosai Hospital, 25 Shogen-cho, Higashi-ku, Hamamatsu city, Shizuoka 430-8525 (Japan); Ogata, Hideki, E-mail: hidogata@gmail.com [Department of Neurosurgery, Hamamatsu Rosai Hospital, 25 Shogen-cho, Higashi-ku, Hamamatsu city, Shizuoka 430-8525 (Japan); Hashimoto, Kenji, E-mail: hashiken8022@yahoo.co.jp [Department of Neurosurgery, Kishiwada Municipal Hospital, 1001 Gakuhara-cho, Kishiwada city, Osaka 596-8501 (Japan); Miyake, Hidenori, E-mail: hi-miyake@hamamatsuh.rofuku.go.jp [Department of Neurosurgery, Hamamatsu Rosai Hospital, 25 Shogen-cho, Higashi-ku, Hamamatsu city, Shizuoka 430-8525 (Japan)

    2014-06-15

    Purpose: The purpose of this study was to investigate the association between internal carotid artery (ICA) stenosis and intramural location and size of calcification at the ICA origins and the origins of the cervical arteries proximal to the ICA. Method: A total of 1139 ICAs were evaluated stenosis and calcification on the multi-detector row CT angiography. The intramural location was categorized into none, outside and inside location. The calcification size was evaluated on the 4-point grading scale. The multivariate analyses were adjusted for age, serum creatinine level, hypertension, hyperlipidemia, diabetes mellitus, smoking and alcohol habits. Results: Outside calcification at the ICA origins showed the highest multivariate odds ratio (OR) for the presence of ICA stenosis (30.0) and severe calcification (a semicircle or more of calcification at the arterial cross-sectional surfaces) did the second (14.3). In the subgroups of >70% ICA stenosis, the multivariate OR of outside location increased to 44.8 and that of severe calcification also increased to 32.7. Four of 5 calcified carotid plaque specimens extracted by carotid endarterectomy were histologically confirmed to be calcified burdens located outside the internal elastic lamia which were defined as arterial medial calcification. Conclusions: ICA stenosis was strongly associated with severe calcification located mainly outside the carotid plaque. Outside calcification at the ICA origins should be evaluated separately from inside calcification, as a marker for the ICA stenosis. Additionally, we found that calcification at the origins of the cervical arteries proximal to the ICA was significantly associated with the ICA stenosis.

  3. Three-dimensional modelling of the human carotid artery using the lattice Boltzmann method: I. Model and velocity analysis

    Science.gov (United States)

    Boyd, J.; Buick, J. M.

    2008-10-01

    Numerical modelling is a powerful tool in the investigation of human blood flow and arterial diseases such as atherosclerosis. It is known that near wall velocity and shear are important in the pathogenesis and progression of atherosclerosis. In this paper results for a simulation of blood flow in a three-dimensional carotid artery geometry using the lattice Boltzmann method are presented. The velocity fields in the body of the fluid are analysed at six times of interest during a physiologically accurate velocity waveform. It is found that the three-dimensional model agrees well with previous literature results for carotid artery flow. Regions of low near wall velocity and circulatory flow are observed near the outer wall of the bifurcation and in the lower regions of the external carotid artery, which are regions that are typically prone to atherosclerosis.

  4. Carotid canal dehiscence in the human skull

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    Pastor Vazquez, J.F.; Gil Verona, J.A. [Department of Anatomy, Faculty of Medicine, University of Valladolid, Ramon y Cajal, 7, E-47005 Valladolid (Spain); Garcia Porrero, M. [Department of Radiology, Faculty of Medicine, University of Valladolid (Spain)

    1999-06-01

    Abnormalities of the floor of the carotid canal have been studied in 538 skulls. These abnormalities range from a fissure to total absence of the floor. This variation may be caused by abnormalities of the internal carotid artery or deficiencies in ossification of the skull base. CT suggests that these changes should be taken into account by surgeons working on the skull base. (orig.) With 4 figs., 8 refs.

  5. Anatomical variations of the carotid arteries in adult Kenyans ...

    African Journals Online (AJOL)

    Objective: To describe the topography and anatomical variations of the carotid arteries among Kenyans. Design: A descriptive cross-sectional study. Setting: Department of Human Anatomy, University of Nairobi. Subjects: Eighty carotid arteries of forty cadavers were dissected. Results: The bifurcation of the commonest ...

  6. Activation of calpain-1 in human carotid artery atherosclerotic lesions

    Directory of Open Access Journals (Sweden)

    Pedro Luis M

    2009-06-01

    Full Text Available Abstract Background In a previous study, we observed that oxidized low-density lipoprotein-induced death of endothelial cells was calpain-1-dependent. The purpose of the present paper was to study the possible activation of calpain in human carotid plaques, and to compare calpain activity in the plaques from symptomatic patients with those obtained from patients without symptoms. Methods Human atherosclerotic carotid plaques (n = 29, 12 associated with symptoms were removed by endarterectomy. Calpain activity and apoptosis were detected by performing immunohistochemical analysis and TUNEL assay on human carotid plaque sections. An antibody specific for calpain-proteolyzed α-fodrin was used on western blots. Results We found that calpain was activated in all the plaques and calpain activity colocalized with apoptotic cell death. Our observation of autoproteolytic cleavage of the 80 kDa subunit of calpain-1 provided further evidence for enzyme activity in the plaque samples. When calpain activity was quantified, we found that plaques from symptomatic patients displayed significantly lower calpain activity compared with asymptomatic plaques. Conclusion These novel results suggest that calpain-1 is commonly active in carotid artery atherosclerotic plaques, and that calpain activity is colocalized with cell death and inversely associated with symptoms.

  7. Tensile and compressive properties of fresh human carotid atherosclerotic plaques.

    LENUS (Irish Health Repository)

    Maher, Eoghan

    2009-12-11

    Accurate characterisation of the mechanical properties of human atherosclerotic plaque is important for our understanding of the role of vascular mechanics in the development and treatment of atherosclerosis. The majority of previous studies investigating the mechanical properties of human plaque are based on tests of plaque tissue removed following autopsy. This study aims to characterise the mechanical behaviour of fresh human carotid plaques removed during endarterectomy and tested within 2h. A total of 50 radial compressive and 17 circumferential tensile uniaxial tests were performed on samples taken from 14 carotid plaques. The clinical classification of each plaque, as determined by duplex ultrasound is also reported. Plaques were classified as calcified, mixed or echolucent. Experimental data indicated that plaques were highly inhomogeneous; with variations seen in the mechanical properties of plaque obtained from individual donors and between donors. The mean behaviour of samples for each classification indicated that calcified plaques had the stiffest response, while echolucent plaques were the least stiff. Results also indicated that there may be a difference in behaviour of samples taken from different anatomical locations (common, internal and external carotid), however the large variability indicates that more testing is needed to reach significant conclusions. This work represents a step towards a better understanding of the in vivo mechanical behaviour of human atherosclerotic plaque.

  8. Microsurgical anatomy of the human carotid body (glomus caroticum): Features of its detailed topography, syntopy and morphology.

    Science.gov (United States)

    Schulz, Sissy-Amelie; Wöhler, Aliona; Beutner, Dirk; Angelov, Doychin N

    2016-03-01

    The human glomus caroticum (GC) is not readily accessible during ordinary anatomical teaching courses because of insufficient time and difficulties encountered in the preparation. Accordingly, most anatomical descriptions of its location, relationship to neighboring structures, size and shape are supported only by drawings, but not by photographs. The aim of this study is to present the GC with all associated roots and branches. Following microscope-assisted dissection and precise photo-documentation, a detailed analysis of location, syntopy and morphology was performed. We carried out this study on 46 bifurcations of the common carotid artery (CCA) into the external (ECA) and internal (ICA) carotid arteries and identified the GC in 40 (91%) of them. We found significant variations regarding the location of the GC and its syntopy: GC was associated with CCA (42%), ECA (28%) and ICA (30%) lying on the medial or lateral surface (82% or 13%, respectively) or exactly in the middle (5%) of the bifurcation. The short and long diameter of its oval form varied from 1.0 × 2.0 to 5.0 × 5.0mm. Connections with the sympathetic trunk (100%), glossopharyngeal (93%), vagus (79%) and hypoglossal nerve (90%) could be established in 29 cadavers. We conclude that precise knowledge of this enormous variety might be very helpful not only to students in medicine and dentistry during anatomical dissection courses, but also to surgeons working in this field. Copyright © 2015 Elsevier GmbH. All rights reserved.

  9. Increased expression of TFPI in human carotid stenosis.

    Science.gov (United States)

    Stavik, Benedicte; Holm, Sverre; Espada, Sandra; Iversen, Nina; Sporsheim, Bjørnar; Bjerkeli, Vigdis; Dahl, Tuva Børresdatter; Sandset, Per Morten; Skjelland, Mona; Espevik, Terje; Skretting, Grethe; Halvorsen, Bente

    2017-07-01

    Tissue factor (TF) pathway inhibitor (TFPI) is the physiological inhibitor of TF induced blood coagulation and two isoforms exists, TFPIα and TFPIβ. In atherosclerotic plaques, TFPI may inhibit TF activity and thrombus formation, which is the main cause of ischemic stroke in carotid artery disease. We aimed to identify the isoforms of TFPI present in human carotid plaques and potential sources of TFPI. Human atherosclerotic plaques from carotid endarterectomies were used for mRNA and immunohistochemistry analyses. hPBMCs isolated from buffy coats and THP-1 cells were differentiated and polarized into M1 or M2 macrophages, and subsequently cultured with or without cholesterol crystals (CC). mRNA and protein expression were measured with qRT-PCR and ELISA, respectively, and procoagulant activity was assessed using a two-stage chromogenic assay. TFPIα and TFPIβ mRNA levels were significantly increased in carotid plaques, whereas TF levels were unchanged as compared to healthy arteries. Antibodies against total TFPI showed elevated levels compared to antibodies against free TFPIα, both by immunohistochemical and ELISA detection in plaques. The antibody against total TFPI also co-localized with CD68 and the M1 and M2 markers CD80 and CD163, respectively. The TFPI mRNA expression was elevated and the procoagulant activity was decreased in M2 compared to M1 polarized human macrophages. TFPI was present in early foam cell formation and CC treatment increased the TFPI mRNA expression even further in M2 macrophages. Our data indicate that both isoforms of TFPI are present in advanced plaques and that anti-inflammatory M2 macrophages may be a potential source of TFPI. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Research Progress on the Risk Factors and Outcomes of Human Carotid Atherosclerotic Plaques.

    Science.gov (United States)

    Xiong, Xiang-Dong; Xiong, Wei-Dong; Xiong, Shang-Shen; Chen, Gui-Hai

    2017-03-20

    Atherosclerosis is an inflammatory process that results in complex lesions or plaques that protrude into the arterial lumen. Carotid atherosclerotic plaque rupture, with distal atheromatous debris embolization, causes cerebrovascular events. This review aimed to explore research progress on the risk factors and outcomes of human carotid atherosclerotic plaques, and the molecular and cellular mechanisms of human carotid atherosclerotic plaque vulnerability for therapeutic intervention. We searched the PubMed database for recently published research articles up to June 2016, with the key words of "risk factors", "outcomes", "blood components", "molecular mechanisms", "cellular mechanisms", and "human carotid atherosclerotic plaques". The articles, regarding the latest developments related to the risk factors and outcomes, atherosclerotic plaque composition, blood components, and consequences of human carotid atherosclerotic plaques, and the molecular and cellular mechanisms of human carotid atherosclerotic plaque vulnerability for therapeutic intervention, were selected. This review described the latest researches regarding the interactive effects of both traditional and novel risk factors for human carotid atherosclerotic plaques, novel insights into human carotid atherosclerotic plaque composition and blood components, and consequences of human carotid atherosclerotic plaque. Carotid plaque biology and serologic biomarkers of vulnerability can be used to predict the risk of cerebrovascular events. Furthermore, plaque composition, rather than lesion burden, seems to most predict rupture and subsequent thrombosis.

  11. Multimodal optoacoustic and multiphoton microscopy of human carotid atheroma

    Directory of Open Access Journals (Sweden)

    Markus Seeger

    2016-09-01

    Full Text Available Carotid artery atherosclerosis is a main cause of stroke. Understanding atherosclerosis biology is critical in the development of targeted prevention and treatment strategies. Consequently, there is demand for advanced tools investigating atheroma pathology. We consider hybrid optoacoustic and multiphoton microscopy for the integrated and complementary interrogation of plaque tissue constituents and their mutual interactions. Herein, we visualize human carotid plaque using a hybrid multimodal imaging system that combines optical resolution optoacoustic (photoacoustic microscopy, second and third harmonic generation microscopy, and two-photon excitation fluorescence microscopy. Our data suggest more comprehensive insights in the pathophysiology of atheroma formation and destabilization, by enabling congruent visualization of structural and biological features critical for the atherosclerotic process and its acute complications, such as red blood cells and collagen.

  12. Assessment of permeation of lipoproteins in human carotid tissue

    Science.gov (United States)

    Ghosn, Mohamad G.; Syed, Saba H.; Leba, Michael; Morrisett, Joel D.; Tuchin, Valery V.; Larin, Kirill V.

    2010-02-01

    Cardiovascular disease is among the leading causes of death in the United States. Specifically, atherosclerosis is an increasingly devastating contributor to the tally and has been found to be a byproduct of arterial permeability irregularities in regards to lipoprotein penetration. To further explore arterial physiology and molecular transport, the imaging technique of Optical Coherence Tomography (OCT) was employed. With OCT, the permeation of glucose (MW = 180 Da), low density lipoprotein (LDL; MW = 2.1 × 106 Da), and high density lipoprotein (HDL; MW = 2.5 × 105 Da) in human carotid tissue was studied to determine the effect of different molecular characteristics on permeation in atherosclerotic tissues. The permeability rates calculated from the diffusion of the molecular agents into the abnormal carotid tissue samples is compared to those of normal, healthy tissue. The results show that in the abnormal tissue, the permeation of agents correlate to the size constraints. The larger molecules of LDL diffuse the slowest, while the smallest molecules of glucose diffuse the fastest. However, in normal tissue, LDL permeates at a faster rate than the other two agents, implying the existence of a transport mechanism that facilitates the passage of LDL molecules. These results highlight the capability of OCT as a sensitive and specific imaging technique as well as provide significant information to the understanding of atherosclerosis and its effect on tissue properties.

  13. Computational modeling of hypertensive growth in the human carotid artery

    Science.gov (United States)

    Sáez, Pablo; Peña, Estefania; Martínez, Miguel Angel; Kuhl, Ellen

    2014-06-01

    Arterial hypertension is a chronic medical condition associated with an elevated blood pressure. Chronic arterial hypertension initiates a series of events, which are known to collectively initiate arterial wall thickening. However, the correlation between macrostructural mechanical loading, microstructural cellular changes, and macrostructural adaptation remains unclear. Here, we present a microstructurally motivated computational model for chronic arterial hypertension through smooth muscle cell growth. To model growth, we adopt a classical concept based on the multiplicative decomposition of the deformation gradient into an elastic part and a growth part. Motivated by clinical observations, we assume that the driving force for growth is the stretch sensed by the smooth muscle cells. We embed our model into a finite element framework, where growth is stored locally as an internal variable. First, to demonstrate the features of our model, we investigate the effects of hypertensive growth in a real human carotid artery. Our results agree nicely with experimental data reported in the literature both qualitatively and quantitatively.

  14. Stent Placement for Carotid Web.

    Science.gov (United States)

    Martinez-Perez, Rafael; Lownie, Stephen P; Pandey, Sachin K; Boulton, Mel R

    2017-02-01

    The carotid web is an intraluminal shelf-like projection arising from the posterior wall of the carotid bifurcation and an uncommon etiology of ischemic strokes. We describe the feasibility of endovascular stent placement to treat this condition. A 47-year-old woman presented with a sudden occlusion of the right middle cerebral artery. Computed tomography angiography and digital subtraction angiography showed a carotid web in the ipsilateral carotid bifurcation. Treatment included mechanical thrombectomy for the middle cerebral artery occlusion and carotid stent placement to prevent further ischemic episodes from the carotid web. At the 6-month follow-up, good apposition of the stent against the artery wall was noted, and the patient was free of neurologic symptoms. Carotid artery stent placement is a feasible option in the management of carotid webs. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. The role of carotid chemoreceptors in the sympathetic activation by adenosine in humans.

    NARCIS (Netherlands)

    Timmers, H.J.L.M.; Rongen, G.A.P.J.M.; Karemaker, J.M.; Wieling, W.; Marres, H.A.M.; Lenders, J.W.M.

    2004-01-01

    The direct vasodilatory and negative chronotropic effects of adenosine in humans are counterbalanced by a reflex increase in sympathetic nerve traffic. A suggested mechanism for this reflex includes peripheral chemoreceptor activation. We, therefore, assessed the contribution of carotid

  16. Relação anatômica entre o nervo hipoglosso e a bifurcação carotídea Anatomical relation between the hypoglossal nerve and the carotid artery bifurcation

    Directory of Open Access Journals (Sweden)

    Felipe S. G. Fortes

    to establish the anatomical relation between the carotid artery bifurcation and hypoglossal nerve. Study design: experimental. Material and method: Carotid artery and hypoglossal nerve dissections were carried out in 38 fresh corpses. All the individuals were placed in standard position and the dissections were performed with surgical technique. The measurements were done in centimeters and millimeters from the dissected carotid bifurcation to the XII nerve in the cervical area. Results: Twenty-six individuals were male and 12 female. The majority were whites, 30, and 8 were non-whites. The distance between hypoglossal nerve and carotid artery bifurcation ranged from 0.5 cm to 4.3 cm, with mean of 2.1 cm, median 2.0 cm and standard deviation of 0.63 cm. Neck length, age, gender and race were related with the measurements and failed to show significant statistic correlation (a > 0.05. Conclusion: In this sample there is a great anatomic variation of the distance between hypoglossal nerve and carotid artery bifurcation and there was no statistical difference concerning age, gender, race and neck length. A better understanding of the anatomic course of this nerve and its variation in relation to carotid artery bifurcation, are relevant to prevent hypoglossal nerve lesions in the carotid artery surgery.

  17. Plasticity of central chemoreceptors: effect of bilateral carotid body resection on central CO2 sensitivity.

    OpenAIRE

    Albert Dahan; Diederik Nieuwenhuijs; Luc Teppema

    2007-01-01

    Background Human breathing is regulated by feedback and feed-forward control mechanisms, allowing a strict matching between metabolic needs and the uptake of oxygen in the lungs. The most important control mechanism, the metabolic ventilatory control system, is fine-tuned by two sets of chemoreceptors, the peripheral chemoreceptors in the carotid bodies (located in the bifurcation of the common carotid arteries) and the central CO2 chemoreceptors in the ventral medulla. Animal data indicate t...

  18. Automaticity in acute ischemia: Bifurcation analysis of a human ventricular model

    Science.gov (United States)

    Bouchard, Sylvain; Jacquemet, Vincent; Vinet, Alain

    2011-01-01

    Acute ischemia (restriction in blood supply to part of the heart as a result of myocardial infarction) induces major changes in the electrophysiological properties of the ventricular tissue. Extracellular potassium concentration ([Ko+]) increases in the ischemic zone, leading to an elevation of the resting membrane potential that creates an “injury current” (IS) between the infarcted and the healthy zone. In addition, the lack of oxygen impairs the metabolic activity of the myocytes and decreases ATP production, thereby affecting ATP-sensitive potassium channels (IKatp). Frequent complications of myocardial infarction are tachycardia, fibrillation, and sudden cardiac death, but the mechanisms underlying their initiation are still debated. One hypothesis is that these arrhythmias may be triggered by abnormal automaticity. We investigated the effect of ischemia on myocyte automaticity by performing a comprehensive bifurcation analysis (fixed points, cycles, and their stability) of a human ventricular myocyte model [K. H. W. J. ten Tusscher and A. V. Panfilov, Am. J. Physiol. Heart Circ. Physiol.AJPHAP0363-613510.1152/ajpheart.00109.2006 291, H1088 (2006)] as a function of three ischemia-relevant parameters [Ko+], IS, and IKatp. In this single-cell model, we found that automatic activity was possible only in the presence of an injury current. Changes in [Ko+] and IKatp significantly altered the bifurcation structure of IS, including the occurrence of early-after depolarization. The results provide a sound basis for studying higher-dimensional tissue structures representing an ischemic heart.

  19. The carotid baroreflex is reset following prolonged exercise in humans

    DEFF Research Database (Denmark)

    Hart, E. C.; Rasmussen, P.; Secher, N. H.

    2010-01-01

    Alterations in the carotid baroreflex (CBR) control of arterial pressure may explain the reduction in arterial pressure and left ventricular (LV) function after prolonged exercise. We examined the CBR control of heart rate (HR) and mean arterial pressure (MAP), in addition to changes in LV functi...

  20. A Single-Cell Roadmap of Lineage Bifurcation in Human ESC Models of Embryonic Brain Development.

    Science.gov (United States)

    Yao, Zizhen; Mich, John K; Ku, Sherman; Menon, Vilas; Krostag, Anne-Rachel; Martinez, Refugio A; Furchtgott, Leon; Mulholland, Heather; Bort, Susan; Fuqua, Margaret A; Gregor, Ben W; Hodge, Rebecca D; Jayabalu, Anu; May, Ryan C; Melton, Samuel; Nelson, Angelique M; Ngo, N Kiet; Shapovalova, Nadiya V; Shehata, Soraya I; Smith, Michael W; Tait, Leah J; Thompson, Carol L; Thomsen, Elliot R; Ye, Chaoyang; Glass, Ian A; Kaykas, Ajamete; Yao, Shuyuan; Phillips, John W; Grimley, Joshua S; Levi, Boaz P; Wang, Yanling; Ramanathan, Sharad

    2017-01-05

    During human brain development, multiple signaling pathways generate diverse cell types with varied regional identities. Here, we integrate single-cell RNA sequencing and clonal analyses to reveal lineage trees and molecular signals underlying early forebrain and mid/hindbrain cell differentiation from human embryonic stem cells (hESCs). Clustering single-cell transcriptomic data identified 41 distinct populations of progenitor, neuronal, and non-neural cells across our differentiation time course. Comparisons with primary mouse and human gene expression data demonstrated rostral and caudal progenitor and neuronal identities from early brain development. Bayesian analyses inferred a unified cell-type lineage tree that bifurcates between cortical and mid/hindbrain cell types. Two methods of clonal analyses confirmed these findings and further revealed the importance of Wnt/β-catenin signaling in controlling this lineage decision. Together, these findings provide a rich transcriptome-based lineage map for studying human brain development and modeling developmental disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Methodology to study intimal failure mechanics in human internal carotid arteries.

    Science.gov (United States)

    Stemper, Brian D; Yoganandan, Narayan; Pintar, Frank A

    2005-12-01

    While the incidence of blunt carotid artery injuries is low, the mortality rate is extremely high (40%). Clinical evidence indicates that the intimal region of the artery often sustains failure, while maintaining the integrity of the outer layers. This condition may lead to delayed ischemic symptoms, commonly reported in clinical literature. To date, the mechanical properties of the intima relative to the outer vessel layers have not been quantified in the human carotid artery. The purpose of the present study was to develop a methodology to determine the longitudinal mechanical properties of the human internal carotid artery in tension, with an emphasis on intimal failure. This was accomplished by opening the vessel at the mid-diameter level, creating an 'I'-shaped testing specimen, subjecting the specimen to failure loading, documenting the stretch characteristics of the intimal and adventitial sides in the temporal domain, and correlating the synchronized videography with mechanical loading. Intimal failure data were quantified using stress and strain parameters in conjunction with digital videography of the intimal and adventitial sides. The present methodology can be used to determine the mechanical properties of the intima relative to ultimate carotid artery failure. These data will assist in the understanding of blunt carotid artery injuries, its diagnosis and treatment.

  2. Electron Bifurcation

    Energy Technology Data Exchange (ETDEWEB)

    Peters, John W.; Miller, Anne-Frances; Jones, Anne K.; King, Paul W.; Adams, Michael W. W.

    2016-04-01

    Electron bifurcation is the recently recognized third mechanism of biological energy conservation. It simultaneously couples exergonic and endergonic oxidation-reduction reactions to circumvent thermodynamic barriers and minimize free energy loss. Little is known about the details of how electron bifurcating enzymes function, but specifics are beginning to emerge for several bifurcating enzymes. To date, those characterized contain a collection of redox cofactors including flavins and iron-sulfur clusters. Here we discuss the current understanding of bifurcating enzymes and the mechanistic features required to reversibly partition multiple electrons from a single redox site into exergonic and endergonic electron transfer paths.

  3. In vivo transfer of lipoprotein(a) into human atherosclerotic carotid arterial intima

    DEFF Research Database (Denmark)

    Nielsen, Lars Bo; Grønholdt, Marie-Louise; Schroeder, T V

    1997-01-01

    The aim of this study was to compare the atherogenic potential of lipoprotein(a) [Lp(a)] and LDL by measuring the intimal clearance of these two plasma lipoproteins in the atherosclerotic intima of the human carotid artery in vivo. Autologous 131I-Lp(a) and 125I-LDL were mixed and reinjected intr...

  4. The role of carotid chemoreceptors in the sympathetic activation by adenosine in humans.

    Science.gov (United States)

    Timmers, Henri J L M; Rongen, Gerard A; Karemaker, John M; Wieling, Wouter; Marres, Henri A M; Lenders, Jacques W M

    2004-01-01

    The direct vasodilatory and negative chronotropic effects of adenosine in humans are counterbalanced by a reflex increase in sympathetic nerve traffic. A suggested mechanism for this reflex includes peripheral chemoreceptor activation. We, therefore, assessed the contribution of carotid chemoreceptors to sympatho-excitation by adenosine. Muscle sympathetic nerve activity was recorded during adenosine infusion (140 microg.kg(-1).min(-1) for 5 min) in five patients lacking carotid chemoreceptors after bilateral carotid body tumour resection (one male and four female, mean age 51 +/- 11 years) and in six healthy controls (two male and four female, mean age 50 +/- 7 years). Sympathetic responses to sodium nitroprusside injections were assessed to measure baroreceptor-mediated sympathetic activation. In response to adenosine, controls showed no change in blood pressure, an increase in heart rate (+48.2 +/- 13.2%; Pactivity (+195 +/- 103%; Pactivity. Adenosine-induced hypotension in individual patients elicited less sympathetic activation than equihypotensive sodium nitroprusside injections. In humans lacking carotid chemoreceptors, adenosine infusion elicits hypotension due to the absence of significant sympatho-excitation. Chemoreceptor activation is essential for counterbalancing the direct vasodilation by adenosine. In addition, blunting of the baroreflex sympathetic response to adenosine-induced hypotension may indicate a direct sympatho-inhibitory effect of adenosine.

  5. Effects of acute hyperthermia on the carotid baroreflex control of heart rate in humans

    Science.gov (United States)

    Yamazaki, F.; Sagawa, S.; Torii, R.; Endo, Y.; Shiraki, K.

    The purpose of this study was to examine the effect of hyperthermia on the carotid baroreceptor-cardiac reflexes in humans. Nine healthy males underwent acute hyperthermia (esophageal temperature 38.0° C) produced by hot water-perfused suits. Beat-to-beat heart rate (HR) responses were determined during positive and negative R-wave-triggered neck pressure steps from +40 to -65 mm Hg during normothermia and hyperthermia. The carotid baroreceptor-cardiac reflex sensitivity was evaluated from the maximum slope of the HR response to changes in carotid distending pressure. Buffering capacity of the HR response to carotid distending pressure was evaluated in % from a reference point calculated as (HR at 0 mm Hg neck pressure-minimum HR)/HR range ×100. An upward shift of the curve was evident in hyperthermia because HR increased from 57.7+/-2.4 beats/min in normothermia to 88.7+/-4.1 beats/min in hyperthermia (Phypotension is reduced and the capacity for bradycardia response to sudden hypertension is increased during acute hyperthermia.

  6. Hypoxia regulates microRNA expression in the human carotid body

    Energy Technology Data Exchange (ETDEWEB)

    Mkrtchian, Souren, E-mail: souren.mkrtchian@ki.se [Section for Anesthesiology and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77 Stockholm (Sweden); Lee, Kian Leong, E-mail: csilkl@nus.edu.sg [Cancer Science Institute of Singapore, National University of Singapore, 117599 Singapore (Singapore); Kåhlin, Jessica [Section for Anesthesiology and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77 Stockholm (Sweden); Function Perioperative Medicine and Intensive Care, Karolinska University Hospital, SE-171 76 Stockholm (Sweden); Ebberyd, Anette [Section for Anesthesiology and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77 Stockholm (Sweden); Poellinger, Lorenz [Cancer Science Institute of Singapore, National University of Singapore, 117599 Singapore (Singapore); Department of Cell and Molecular Biology, Karolinska Institute, SE-171 77 Stockholm (Sweden); Fagerlund, Malin Jonsson; Eriksson, Lars I. [Section for Anesthesiology and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77 Stockholm (Sweden); Function Perioperative Medicine and Intensive Care, Karolinska University Hospital, SE-171 76 Stockholm (Sweden)

    2017-03-15

    The carotid body (CB) is the key sensing organ for physiological oxygen levels in the body. Under conditions of low oxygen (hypoxia), the CB plays crucial roles in signaling to the cardiorespiratory center in the medulla oblongata for the restoration of oxygen homeostasis. How hypoxia regulates gene expression in the human CB remains poorly understood. While limited information on transcriptional regulation in animal CBs is available, the identity and impact of important post-transcriptional regulators such as non-coding RNAs, and in particular miRNAs are not known. Here we show using ex vivo experiments that indeed a number of miRNAs are differentially regulated in surgically removed human CB slices when acute hypoxic conditions were applied. Analysis of the hypoxia-regulated miRNAs shows that they target biological pathways with upregulation of functions related to cell proliferation and immune response and downregulation of cell differentiation and cell death functions. Comparative analysis of the human CB miRNAome with the global miRNA expression patterns of a large number of different human tissues showed that the CB miRNAome had a unique profile which reflects its highly specialized functional status. Nevertheless, the human CB miRNAome is most closely related to the miRNA expression pattern of brain tissues indicating that they may have the most similar developmental origins. - Highlights: • Hypoxia triggers differential expression of many miRNAs in the human carotid body. • This can lead to the upregulation of proliferation and immune response functions. • CB expression profile in the carotid body resembles the miRNA expression pattern in the brain. • miRNAs are involved in the regulation of carotid body functions including oxygen sensing.

  7. Fluid-structure interaction analysis on the effect of vessel wall hypertrophy and stiffness on the blood flow in carotid artery bifurcation

    Science.gov (United States)

    Lee, Sang Hoon; Choi, Hyoung Gwon; Yoo, Jung Yul

    2012-11-01

    The effect of artery wall hypertrophy and stiffness on the flow field is investigated using three-dimensional finite element method for simulating the blood flow. To avoid the complexity due to the necessity of additional mechanical constraints, we use the combined formulation which includes both the fluid and structural equations of motion into single coupled variational equation. A P2P1 Galerkin finite element method is used to solve the Navier-Stokes equations for fluid flow and arbitrary Lagrangian-Eulerian formulation is used to achieve mesh movement. The Newmark method is employed for solving the dynamic equilibrium equations for linear elastic solid mechanics. The pulsatile, incompressible flows of Newtonian fluids constrained in the flexible wall are analyzed with Womersley velocity profile at the inlet and constant pressure at the outlet. The study shows that the stiffness of carotid artery wall affects significantly the flow phenomena during the pulse cycle. Similarly, it is found that the flow field is also strongly influenced by wall hypertrophy. This work was supported by Mid-career Researcher Program and Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2009-0079936 & 2011-0029613).

  8. Mapeamento ecográfico da bifurcação das artérias carótidas extracranianas para planejamento cirúrgico: diferenças baseadas no gênero do paciente Ultrasonographic mapping of the extracranial carotid artery bifurcation for surgical planning: gender differences

    Directory of Open Access Journals (Sweden)

    Sandra Maria Pontes

    2011-09-01

    Full Text Available CONTEXTO: A ecografia das artérias carótidas extracranianas já se estabeleceu como método diagnóstico de imagem pré-operatória, e para seguimento de pacientes. OBJETIVO: Avaliar diferenças do mapeamento ecográfico em função do gênero masculino ou feminino dos pacientes. MÉTODOS: Ultrassonografia de alta resolução foi realizada antes do tratamento cirúrgico de 500 bifurcações carotídeas em 192 mulheres e 308 homens. Análise de diferenças baseadas no gênero foi feita em imagens modo B e fluxo a cor, transversal e longitudinal, e medidas duplex doppler de velocidades. Porcentual de estenose expressa em redução de diâmetro, comprimento de placa, diâmetros das artérias carótida interna distal e comum, e distância da bifurcação ao lóbulo da orelha foram comparados. Média, desvio padrão, mínimo e máximo foram descritos. Comparações estatísticas foram baseadas em testes t de Student e do Χ2. RESULTADOS: Estenoses carotídeas mediram 70±11% (30-95% em mulheres e 72±12% (40-98% em homens (p=0,013. Prevalência de estenoses no intervalo 90-99% foi mais alta em homens, 14,3 vs 7,8% (p=0,029. As placas foram mais extensas nos homens, 2,3±0,8 vs 1,9±0,6 cm (pCONTEXT: Doppler ultrasonography is an established method for diagnosis, preoperative imaging and follow-up of extracranial carotid artery disease. OBJETIVE: The evaluation of gender differences in carotid artery bifurcation Doppler ultrasonography mapping. METHODS: High resolution Doppler ultrasonography of 500 carotid bifurcations was performed in 192 women and 308 men before surgical treatment. Gender differences were analyzed based on B-mode, color-flow, duplex doppler transverse and longitudinal images. Diameter percent stenoses, plaque length, distal internal and common carotid artery diameters, and distance from the carotid bifurcation to the ear lobe were compared. Mean, standard deviation, minimum and maximum values were described. Statistical

  9. Dual roles of heparanase in vascular calcification associated with human carotid atherosclerosis

    DEFF Research Database (Denmark)

    Aldi, S.; Eriksson, L.; Kronqvist, M.

    2017-01-01

    Vascular intimal calcification is a hallmark of advanced atherosclerosis and an active process akin to bone remodeling. Heparanase (HPSE) is an endo-β-glucuronidase, which cleaves glycosaminoglycan chains of heparan sulfate proteoglycans. The role of heparanase in osteogenesis and bone remodeling...... is controversial. Previously, we have reported the upregulation of HPSE in human carotid endarterectomies from symptomatic patients and showed that the HPSE expression levels correlated with markers of inflammation and increased thrombogenicity....

  10. Dynamic Bifurcations

    CERN Document Server

    1991-01-01

    Dynamical Bifurcation Theory is concerned with the phenomena that occur in one parameter families of dynamical systems (usually ordinary differential equations), when the parameter is a slowly varying function of time. During the last decade these phenomena were observed and studied by many mathematicians, both pure and applied, from eastern and western countries, using classical and nonstandard analysis. It is the purpose of this book to give an account of these developments. The first paper, by C. Lobry, is an introduction: the reader will find here an explanation of the problems and some easy examples; this paper also explains the role of each of the other paper within the volume and their relationship to one another. CONTENTS: C. Lobry: Dynamic Bifurcations.- T. Erneux, E.L. Reiss, L.J. Holden, M. Georgiou: Slow Passage through Bifurcation and Limit Points. Asymptotic Theory and Applications.- M. Canalis-Durand: Formal Expansion of van der Pol Equation Canard Solutions are Gevrey.- V. Gautheron, E. Isambe...

  11. The human carotid body transcriptome with focus on oxygen sensing and inflammation--a comparative analysis.

    Science.gov (United States)

    Mkrtchian, Souren; Kåhlin, Jessica; Ebberyd, Anette; Gonzalez, Constancio; Sanchez, Diego; Balbir, Alexander; Kostuk, Eric W; Shirahata, Machiko; Fagerlund, Malin Jonsson; Eriksson, Lars I

    2012-08-15

    The carotid body (CB) is the key oxygen sensing organ. While the expression of CB specific genes is relatively well studied in animals, corresponding data for the human CB are missing. In this study we used five surgically removed human CBs to characterize the CB transcriptome with microarray and PCR analyses, and compared the results with mice data. In silico approaches demonstrated a unique gene expression profile of the human and mouse CB transcriptomes and an unexpected upregulation of both human and mouse CB genes involved in the inflammatory response compared to brain and adrenal gland data. Human CBs express most of the genes previously proposed to be involved in oxygen sensing and signalling based on animal studies, including NOX2, AMPK, CSE and oxygen sensitive K+ channels. In the TASK subfamily of K+ channels, TASK-1 is expressed in human CBs, while TASK-3 and TASK-5 are absent, although we demonstrated both TASK-1 and TASK-3 in one of the mouse reference strains. Maxi-K was expressed exclusively as the spliced variant ZERO in the human CB. In summary, the human CB transcriptome shares important features with the mouse CB, but also differs significantly in the expression of a number of CB chemosensory genes. This study provides key information for future functional investigations on the human carotid body.

  12. Impact of age and sex on carotid and peripheral arterial wall thickness in humans.

    Science.gov (United States)

    van den Munckhof, I; Scholten, R; Cable, N T; Hopman, M T E; Green, D J; Thijssen, D H J

    2012-12-01

    Although previous studies have reported age-related wall thickening in carotid arteries, it is not clear whether this is a systemic phenomenon which is also apparent in peripheral conduit arteries or whether conduit wall thickness (WT) changes occur to a similar degree in men and women. To determine whether sex modifies the impact of ageing on WT or wall-to-lumen ratio (W:L) in atherosclerosis-prone (i.e. carotid artery, femoral, superficial femoral, popliteal artery) and atherosclerosis-resistant (i.e. brachial artery) conduit arteries. We included 30 young (23 ± 2 year; 15M : 15F) and 31 older (70 ± 5 year; 18M : 13F) healthy subjects. High-resolution ultrasound was used to measure diameter, WT and wall-to-lumen ratio (W/L) in all arteries. Older subjects had increased WT and W/L in the carotid, femoral, superficial femoral, popliteal and brachial arteries (all P < 0.05). Compared with women, men demonstrated larger diameter and WT (both P < 0.01) across all arteries. Sex did not impact upon age-related changes in WT or W/L (P = 0.39 and 0.43 respectively). Our data suggest that age-related wall thickening, evident in the carotid artery, is also apparent in the arteries of the upper and lower limbs. The impact of age on wall thickening did not differ between men and women. These data support the presence of systemic increases in WT and W/L with age in apparently healthy humans, independent of sex. © 2012 The Authors Acta Physiologica © 2012 Scandinavian Physiological Society.

  13. External ventricular drain as a nontraumatic suction device in carotid endarterectomy

    OpenAIRE

    Jukes, Alistair; Allan, Rodney

    2017-01-01

    Carotid endarterectomy is a commonly performed operation to remove plaque at the region of the carotid bifurcation. We present our technique to keep the field clear and to minimize potential trauma to the carotid using a neurosurgical external ventricular drain passed behind the common carotid and placed in the dependent position under the arteriotomy.

  14. External ventricular drain as a nontraumatic suction device in carotid endarterectomy

    Directory of Open Access Journals (Sweden)

    Alistair Jukes, MBBS(Hons, BLibStud

    2017-03-01

    Full Text Available Carotid endarterectomy is a commonly performed operation to remove plaque at the region of the carotid bifurcation. We present our technique to keep the field clear and to minimize potential trauma to the carotid using a neurosurgical external ventricular drain passed behind the common carotid and placed in the dependent position under the arteriotomy.

  15. Laser microdissection-based analysis of hypoxia- and thioredoxin-related genes in human stable carotid plaques.

    Science.gov (United States)

    Okami, Nobuya; Kawamata, Takakazu; Yamamoto, Gou; Okada, Yoshikazu; Hori, Tomokatsu; Tachikawa, Tetsuhiko

    2009-01-01

    Neovascularization in the carotid atherosclerotic plaque is a common pathogenetic feature in carotid artery stenosis. To investigate whether the neovascular region of the stable plaque differentially expresses specific genes, we analyzed the patterns of angiogenesis-related gene expression in regions of the plaque isolated by laser microdissection and examined by immunohistochemistry and real-time reverse transcription (RT)-polymerase chain reaction (PCR). Carotid plaque samples were obtained by carotid endarterectomy in 27 clinically asymptomatic patients with high-grade internal carotid artery stenosis. Among these 27 plaque samples, 23 plaques were confirmed to be stable pathologically, and 14 stable plaques had neovascularization. The medial, shoulder, and neovascular regions of the 14 carotid plaques were determined by immunohistochemical staining. These 3 regions were microdissected, and total RNA was extracted for real-time RT-PCR analysis. The expressions of hypoxia inducible factor 1alpha, vascular endothelial growth factor-A, thioredoxin, and thioredoxin interacting protein were analyzed at mRNA level. Real-time RT-PCR was performed on 42 laser microdissected regions of 14 plaques. The expressions of all four genes examined were significantly lower in the medial region at mRNA level. High expressions were noted in both shoulder and neovascular regions, with no significant difference between the two. Furthermore, these expression patterns were related significantly to macrophage infiltration. In conclusion, hypoxia- and thioredoxin-related genes are significantly overexpressed in human stable carotid atherosclerotic plaques and strongly correlate with macrophage infiltration rather than neovascularization. Macrophage infiltration may lead to overexpression of these genes and promote angiogenesis in stable carotid plaques.

  16. Hybrid microscopy of human carotid atheroma by means of optical-resolution optoacoustic and non-linear optical microscopy

    Science.gov (United States)

    Seeger, Markus; Karlas, Angelos; Soliman, Dominik; Pelisek, Jaroslav; Ntziachristos, Vasilis

    2017-03-01

    Carotid atheromatosis is causally related to stroke, a leading cause of disability and death. We present the analysis of a human carotid atheroma using a novel hybrid microscopy system that combines optical-resolution optoacoustic (photoacoustic) microscopy and several non-linear optical microscopy modalities (second and third harmonic generation, as well as, two-photon excitation fluorescence) to achieve a multimodal examination of the extracted tissue within the same imaging framework. Our system enables the label-free investigation of atheromatous human carotid tissue with a resolution of about 1 μm and allows for the congruent interrogation of plaque morphology and clinically relevant constituents such as red blood cells, collagen, and elastin. Our data reveal mutual interactions between blood embeddings and connective tissue within the atheroma, offering comprehensive insights into its stage of evolution and severity, and potentially facilitating the further development of diagnostic tools, as well as treatment strategies.

  17. [Carotid body paraganglioma in a teenager. Case report].

    Science.gov (United States)

    López-Vázquez, María Elisa; Llamas-Macías, Francisco Javier; Nuño-Escobar, César; González-Ojeda, Alejandro; Fuentes-Orozco, Clotilde; Macías-Amezcua, Michel Dassaejv

    2014-01-01

    Paragangliomas of the head and neck are neuroendocrine tumors. They have a low incidence (0.6%), are generally benign, have a poorly defined etiology, and multiple factors have been associated with their origin. Humans and other species living at high altitudes (>2000 m above sea level) are subjected to a relatively chronic hypoxia and there is a high prevalence of the development of carotid body hyperplasia and eventually paragangliomas. This disease is usually seen in patients in their 50s and in their 30s if there is a family history. We present the case of a 16 year-old female with acute pharyngitis and growing tumor located on the left side of the neck, without symptoms. A duplex Doppler ultrasound showed a solid nodular lesion on the left carotid bifurcation. A left lateral cervicotomy was performed, finding a highly vascularized tumor of 4 × 3 × 3 cm involving the common carotid from its middle third, the internal carotid up to the cranial base, and the external carotid to its upper third, and intimately related to the trachea, esophagus and cervical spine. The tumor was completely resected and the histopathological analysis corroborated the presence of paragangliomas. The publication of this case is relevant and of clinical interest due to the uncommon age of presentation and the fact that it should be considered as a diagnostic possibility.

  18. Association between Human Plasma Chondroitin Sulfate Isomers and Carotid Atherosclerotic Plaques

    Directory of Open Access Journals (Sweden)

    Elisabetta Zinellu

    2012-01-01

    Full Text Available Several studies have evidenced variations in plasma glycosaminoglycans content in physiological and pathological conditions. In normal human plasma GAGs are present mainly as undersulfated chondroitin sulfate (CS. The aim of the present study was to evaluate possible correlations between plasma CS level/structure and the presence/typology of carotid atherosclerotic lesion. Plasma CS was purified from 46 control subjects and 47 patients undergoing carotid endarterectomy showing either a soft or a hard plaque. The concentration and structural characteristics of plasma CS were assessed by capillary electrophoresis of constituent unsaturated fluorophore-labeled disaccharides. Results showed that the concentration of total CS isomers was increased by 21.4% (P<0.01 in plasma of patients, due to a significant increase of undersulfated CS. Consequently, in patients the plasma CS charge density was significantly reduced with respect to that of controls. After sorting for plaque typology, we found that patients with soft plaques and those with hard ones differently contribute to the observed changes. In plasma from patients with soft plaques, the increase in CS content was not associated with modifications of its sulfation pattern. On the contrary, the presence of hard plaques was associated with CS sulfation pattern modifications in presence of quite normal total CS isomers levels. These results suggest that the plasma CS content and structure could be related to the presence and the typology of atherosclerotic plaque and could provide a useful diagnostic tool, as well as information on the molecular mechanisms responsible for plaque instability.

  19. Effect of dynamic exercise on human carotid-cardiac baroreflex latency

    Science.gov (United States)

    Potts, J. T.; Raven, P. B.

    1995-01-01

    We compared the beat-to-beat responses of heart rate (HR) after brief activation of carotid baroreceptors in resting humans with the responses obtained during mild-to-moderate levels of dynamic exercise [25 and 50% of peak O2 uptake (VO2peak)] to investigate the effect of exercise on baroreflex latency. Carotid baroreceptors were activated by a pressure pulse (5 s) of neck suction (NS, -80 Torr) and neck pressure (NP, +40 Torr) during held expiration. At rest the peak change in HR to NS/NP occurred during the first several heartbeats (1st-3rd beat), whereas during mild and moderate exercise peak HR responses occurred near the end of the NS/NP pulse (6th-8th beat). In contrast, time (s) to the peak change in HR was not different between rest and exercise (P > 0.05). Reflex tachycadia to NP progressively decreased during exercise (17 +/- 3, 10 +/- 1, and 4 +/- 1% of control, rest vs. 25% VO2peak, vs. 50% VO2peak, respectively, P tachycardia and a measure of HR variability (cardiac vagal tone index, r = 0.74, P < 0.0001). Reflex bradycardia to NS gradually increased during exercise (13 +/- 2, 17 +/- 2, and 18 +/- 2% of control, rest vs. 25% VO2peak, vs. 50% VO2peak, respectively, P = 0.10) and was negatively correlated with cardiac vagal tone (r = 0.42, P < 0.06).(ABSTRACT TRUNCATED AT 250 WORDS).

  20. Carotid Ultrasound

    Science.gov (United States)

    ... this page from the NHLBI on Twitter. Carotid Ultrasound Also known as carotid duplex. Carotid ultrasound is a painless imaging test that uses high- ... of your carotid arteries. This test uses an ultrasound machine, which includes a computer, a screen, and ...

  1. Feasibility of in vivo {sup 18}F-florbetaben PET/MR imaging of human carotid amyloid-β

    Energy Technology Data Exchange (ETDEWEB)

    Bucerius, Jan [Maastricht University Medical Center (MUMC+), Department of Radiology/Nuclear Medicine, Maastricht (Netherlands); Maastricht University Medical Center (MUMC+), Cardiovascular Research Institute Maastricht (CARIM), Maastricht (Netherlands); University Hospital RWTH Aachen, Department of Nuclear Medicine, Aachen (Germany); Maastricht University Medical Center (MUMC+), Department of Nuclear Medicine/Radiology and Cardiovascular Research Institute Maastricht (CARIM), Maastricht (Netherlands); Barthel, Henryk; Tiepolt, Solveig; Werner, Peter; Patt, Marianne; Sabri, Osama [Leipzig University Medical Centre, Department of Nuclear Medicine, Leipzig (Germany); Sluimer, Judith C.; Biessen, Erik A.L. [Maastricht University Medical Center (MUMC+), Department of Pathology, Experimental Vascular Pathology, Maastricht (Netherlands); Wildberger, Joachim E. [Maastricht University Medical Center (MUMC+), Department of Radiology/Nuclear Medicine, Maastricht (Netherlands); Maastricht University Medical Center (MUMC+), Cardiovascular Research Institute Maastricht (CARIM), Maastricht (Netherlands); Hesse, Swen [Leipzig University Medical Centre, Department of Nuclear Medicine, Leipzig (Germany); Leipzig University Medical Centre, Integrated Treatment and Research Centre (IFB) Adiposity Diseases, Leipzig (Germany); Gertz, Hermann-Josef [Leipzig University Medical Centre, Department of Psychiatry, Leipzig (Germany); Mottaghy, Felix M. [Maastricht University Medical Center (MUMC+), Department of Radiology/Nuclear Medicine, Maastricht (Netherlands); University Hospital RWTH Aachen, Department of Nuclear Medicine, Aachen (Germany)

    2017-07-15

    Amyloid-beta (Aβ) peptides are involved in the inflammatory pathology of atherosclerosis. {sup 18}F-Florbetaben is a PET tracer for clinical imaging of cerebral Aβ plaques in Alzheimer's disease (AD). We sought to determine whether specific uptake of {sup 18}F-florbetaben in the carotid arteries can be identified using a fully integrated hybrid PET/MRI system and whether this uptake is associated with clinical cardiovascular disease (CVD) risk factors. Carotid {sup 18}F-florbetaben uptake was quantified as the mean of the maximum target-to-background ratio ({sub mean}TBR{sub max}) in 40 cognitively impaired subjects (age 68.2 ± 9.5 years) undergoing {sup 18}F-florbetaben PET/MRI to diagnose AD. Associations between carotid {sup 18}F-florbetaben uptake and several CVD risk factors were assessed by univariate analysis followed by a multivariate linear regression analysis. Furthermore, carotid {sup 18}F-florbetaben uptake was compared between patients with and without a positive cerebral Aβ PET scan. {sup 18}F-Florbetaben uptake was clearly visualized in the carotid arteries. Values of{sub mean}TBR{sub max} corrected for the blood pool activity of the tracer showed specific {sup 18}F-florbetaben uptake in the carotid wall. Male gender was associated with carotid {sup 18}F-florbetaben uptake in the univariate analysis, and was found to be an independent predictor of {sup 18}F-florbetaben uptake in the multivariate regression analysis (standardized regression coefficient β = 0.407, p = 0.009). Carotid {sup 18}F-florbetaben{sub mean}TBR{sub max} in patients with a positive cerebral Aβ scan did not differ from that in patients without cerebral Aβ deposits. Specific {sup 18}F-florbetaben uptake in human carotid arteries was detected. Male gender was identified as an independent clinical risk factor. Therefore, {sup 18}F-florbetaben PET/MRI might provide new insights into the pathophysiological process in atherosclerosis. (orig.)

  2. Bilateral symmetry of local inflammatory activation in human carotid atherosclerotic plaques.

    Science.gov (United States)

    Benetos, Georgios; Toutouzas, Konstantinos; Drakopoulou, Maria; Tolis, Elias; Masoura, Constantina; Nikolaou, Charalampia; Tsekoura, Dorothea; Tsiamis, Eleftherios; Grassos, Harris; Siores, Elias; Stefanadis, Christodoulos; Tousoulis, Dimitris

    2015-01-01

    Only a few studies have investigated the structural and functional characteristics of carotid arteries bilaterally. Furthermore, there is controversy as to whether inflammation in paired vascular beds is a local or systemic phenomenon. We aimed to examine, in patients with coronary artery disease, whether intra-subject left and right carotid arteries have similar inflammatory status, as determined non-invasively by microwave radiometry (MWR). Consecutive patients (n=200) with significant coronary artery disease were evaluated via an ultrasound echo-colour Doppler (US-ECD) study of both carotid arteries and temperature measurements with MWR. During thermography, thermal heterogeneity (ΔT) was defined as the maximum temperature along the carotid artery minus the minimum temperature. Mean T was similar between the left and right carotid arteries (0.78 ± 0.48 vs. 0.84 ± 0.52°C, p=0.12). Mean right intima-media thickness (IMT) was greater compared to mean left IMT (2.16 ± 1.20 vs. 1.93 ± 0.94 mm, p<0.01). In all carotids, there was a correlation between left and right carotid plaque ΔT (R=0.38, p<0.001) and between left and right IMT (R=0.48, p<0.001). Independent predictors for the presence of bilateral carotid plaques were found to be the extent of coronary artery disease, high ΔT, and therapy with angiotensin II receptor blockers; predictors for the presence of high ΔT bilaterally were bilateral carotid plaques, male sex, diabetes mellitus, and hypertension. There is bilateral inflammatory activation in the carotid atherosclerotic lesions of patients with coronary artery disease. At this stage of carotid disease, arterial hypertension and diabetes mellitus are more strongly correlated with bilateral functional abnormalities in carotid plaques than with structural changes.

  3. Cell population structure prior to bifurcation predicts efficiency of directed differentiation in human induced pluripotent cells.

    Science.gov (United States)

    Bargaje, Rhishikesh; Trachana, Kalliopi; Shelton, Martin N; McGinnis, Christopher S; Zhou, Joseph X; Chadick, Cora; Cook, Savannah; Cavanaugh, Christopher; Huang, Sui; Hood, Leroy

    2017-02-28

    Steering the differentiation of induced pluripotent stem cells (iPSCs) toward specific cell types is crucial for patient-specific disease modeling and drug testing. This effort requires the capacity to predict and control when and how multipotent progenitor cells commit to the desired cell fate. Cell fate commitment represents a critical state transition or "tipping point" at which complex systems undergo a sudden qualitative shift. To characterize such transitions during iPSC to cardiomyocyte differentiation, we analyzed the gene expression patterns of 96 developmental genes at single-cell resolution. We identified a bifurcation event early in the trajectory when a primitive streak-like cell population segregated into the mesodermal and endodermal lineages. Before this branching point, we could detect the signature of an imminent critical transition: increase in cell heterogeneity and coordination of gene expression. Correlation analysis of gene expression profiles at the tipping point indicates transcription factors that drive the state transition toward each alternative cell fate and their relationships with specific phenotypic readouts. The latter helps us to facilitate small molecule screening for differentiation efficiency. To this end, we set up an analysis of cell population structure at the tipping point after systematic variation of the protocol to bias the differentiation toward mesodermal or endodermal cell lineage. We were able to predict the proportion of cardiomyocytes many days before cells manifest the differentiated phenotype. The analysis of cell populations undergoing a critical state transition thus affords a tool to forecast cell fate outcomes and can be used to optimize differentiation protocols to obtain desired cell populations.

  4. Novel flow quantification of the carotid bulb and the common carotid artery with vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Haugaard, Per

    2014-01-01

    complexity. A secondary aim was to establish accuracy parameters to detect flow changes/patterns in the common carotid artery (CCA) and the carotid bulb (CB). The right carotid bifurcation including the CCA and CB of eight healthy volunteers were scanned in a longitudinal plane with vector flow ultrasound...... and by vector concentration calculation. A vortex with complex flow was found in all carotid bulbs, whereas the CCA had mainly laminar flow. The medical experts evaluated the flow to be mainly laminar in the CCA (0.82 +/- 0.14) and mainly complex (0.23 +/- 0.22) in the CB. Likewise, the estimated vector...

  5. KISS1 and KISS1R expression in the human and rat carotid body and superior cervical ganglion

    Directory of Open Access Journals (Sweden)

    A. Porzionato

    2011-05-01

    Full Text Available KISS1 and its receptor, KISS1R, have both been found to be expressed in central nervous system, but few data are present in the literature about their distribution in peripheral nervous structures. Thus, the aim of the present study was to investigate, through immunohistochemistry, the expression and distribution of KISS1 and KISS1R in the rat and human carotid bodies and superior cervical ganglia, also with particular reference to the different cellular populations. Materials consisted of carotid bodies and superior cervical ganglia were obtained at autopsy from 10 adult subjects and sampled from 10 adult Sprague-Dawley rats. Immunohistochemistry revealed diffuse expression of KISS1 and KISS1R in type I cells of both human and rat carotid bodies, whereas type II cells were negative. In both human and rat superior cervical ganglia positive anti-KISS1 and -KISS1R immunostainings were also selectively found in ganglion cells, satellite cells being negative. Endothelial cells also showed moderate immunostaining for both KISS1 and KISS1R. The expression of both kisspeptins and kisspeptin receptors in glomic type I cells and sympathetic ganglion cells supports a modulatory role of KISS1 on peripheral chemoreception and sympathetic function. Moreover, local changes in blood flow have been considered to be involved in carotid body chemoreceptor discharge and kisspeptins and kisspeptin receptors have also been found in the endothelial cells. As a consequence, a possible role of kisspeptins in the regulation of carotid body blood flow and, indirectly, in chemoreceptor discharge may also be hypothesized.

  6. MR imaging of carotid webs

    Energy Technology Data Exchange (ETDEWEB)

    Boesen, Mari E. [University of Calgary, Department of Biomedical Engineering, Calgary (Canada); Foothills Medical Centre, Seaman Family MR Research Centre, Calgary (Canada); Eswaradass, Prasanna Venkatesan; Singh, Dilip; Mitha, Alim P.; Menon, Bijoy K. [University of Calgary, Department of Clinical Neurosciences, Calgary (Canada); Foothills Medical Centre, Calgary Stroke Program, Calgary (Canada); Goyal, Mayank [Foothills Medical Centre, Calgary Stroke Program, Calgary (Canada); University of Calgary, Department of Radiology, Calgary (Canada); Frayne, Richard [Foothills Medical Centre, Seaman Family MR Research Centre, Calgary (Canada); University of Calgary, Hotchkiss Brain Institute, Calgary (Canada)

    2017-04-15

    We propose a magnetic resonance (MR) imaging protocol for the characterization of carotid web morphology, composition, and vessel wall dynamics. The purpose of this case series was to determine the feasibility of imaging carotid webs with MR imaging. Five patients diagnosed with carotid web on CT angiography were recruited to undergo a 30-min MR imaging session. MR angiography (MRA) images of the carotid artery bifurcation were acquired. Multi-contrast fast spin echo (FSE) images were acquired axially about the level of the carotid web. Two types of cardiac phase resolved sequences (cineFSE and cine phase contrast) were acquired to visualize the elasticity of the vessel wall affected by the web. Carotid webs were identified on MRA in 5/5 (100%) patients. Multi-contrast FSE revealed vessel wall thickening and cineFSE demonstrated regional changes in distensibility surrounding the webs in these patients. Our MR imaging protocol enables an in-depth evaluation of patients with carotid webs: morphology (by MRA), composition (by multi-contrast FSE), and wall dynamics (by cineFSE). (orig.)

  7. Perspective: carotid stenting and the history of disruptive technology in vascular surgery.

    Science.gov (United States)

    Veith, Frank J

    2008-06-01

    This article defines disruptive technology and discusses such technologies in Vascular Surgery. It considers the question: Is carotid artery stenting (CAS) a disruptive technology? Although CAS will impact positively on the treatment of carotid bifurcation disease, it will probably never displace carotid endarterectomy in the majority of patients. The precise role of CAS remains to be determined.

  8. Bilateral carotid artery injury response in side impact using a vessel model integrated with a human body model.

    Science.gov (United States)

    Danelson, Kerry A; Gayzik, F Scott; Yu, Mao M; Martin, R Shayn; Duma, Stefan M; Stitzel, Joel D

    2009-10-01

    In a far-side crash configuration, the occupant can experience severe excursion from the seat space. Given this challenge, there are research efforts focused on alternate restraints, such as four-point belts. A potential implication of this geometry would be interaction of the belt with the occupant's neck. This study examines the response of the carotid arteries using a Finite Element Model (FEM) in a far-side crash configuration with a reversed three-point restraint. A FEM of the carotid artery and neck fascia was developed and integrated with the Total Human Model for Safety (THUMS) version 1.44. This model was subjected to four test conditions simulating far-side crashes. Load conditions included a low velocity impact of approximately 4 m/s and a higher velocity impact of approximately 10 m/s. For each velocity, the model was restrained with a belt placed low on the neck and a belt placed higher on the neck. Strain data in each element of the carotid arteries was analyzed. The overall response of the vessel was examined to determine locations of high strain values. Low belt placement resulted in more head excursion, stretching the carotid on the non-struck side. High belt placement resulted in compression of the artery on the struck side due to direct loading of the vessel from the belt. Strain values in the carotid artery elements increased with increasing speed of impact. The lower and higher speed tests with a low belt configuration resulted in a maximum principal strains, at maximal belt engagement, of 0.223 and 0.459, respectively. Corresponding values for the high belt configuration were 0.222 and 0.563. In both belt configurations, the non-struck side vessel stretched more than the struck side vessel; however, the non-struck side vessel experienced higher compressive forces. Strain values measured during the simulations can be compared to a value of 0.31 to intimal failure in previous experimental tests. These results quantitatively illustrate the two

  9. The baboon (Papio anubis extracranial carotid artery: An anatomical guide for endovascular experimentation

    Directory of Open Access Journals (Sweden)

    Laufer Ilya

    2001-12-01

    Full Text Available Abstract Background As novel endovascular strategies are developed for treating neurological disease, there is an increasing need to evaluate these techniques in relevant preclinical models. The use of non-human primates is especially critical given their structural and physiological homology with humans. In order to conduct primate endovascular studies, a comprehensive understanding of the carotid anatomy is necessary. We therefore performed a detailed examination of the vessel lengths, lumen diameters and angles of origin of the baboon extracranial carotid system. Methods We characterized the extracranial carotid system often male baboons (Papio anubis, range 15.1–28.4 kg by early post-mortem dissection. Photographic documentation of vessel lengths, lumen diameters, and angles of origin were measured for each segment of the carotid bilaterally. Results The common carotid arteries averaged 94.7 ± 1.7 mm (left and 87.1 ± 1.6 mm (right in length. The average minimal common carotid lumen diameters were 3.0 ± 0.3 mm (left and 2.9 ± 0.2 mm (right. Each animal had a common brachiocephalic artery arising from the aorta which bifurcated into the left common carotid artery and right braciocephalic artery after 21.5 ± 1.6 mm. The vascular anatomy was found to be consistent among animals despite a wide range of animal weights. Conclusions The consistency in the Papio anubis extracranial carotid system may promote the use of this species in the preclinical investigation of neuro-interventional therapies.

  10. A cardiologist in the carotids.

    Science.gov (United States)

    Gray, William A

    2004-05-05

    Carotid endarterectomy for stroke prevention has been the standard of care for 50 years in patients with extra-cranial carotid bifurcation disease. Over the past decade, carotid stenting has emerged as a viable alternative to surgery. Combined with filter embolic protection devices, both a randomized control trial (Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy registry [SAPPHIRE]) as well as registry data (ACCULINK for Revascularization of Carotids in High Risk Patients registry [ARCHeR] and Registry Study to evaluate the Neuroshield Bare-Wire Cerebral Protection System and X-Act Stent in patients at high risk for Carotid Endarterectomy [SECuRITY]) have compared favorably to endarterectomy in patients at high risk for operative revascularization. Conditions associated with high operative risk included patients with significant cardiac, pulmonary, and renal disease; previous neck operation; previous radiation; and anatomically difficult surgical access. On the basis of these results, a carotid stent system approved by the Food and Drug Administration (FDA) is anticipated in 2004. Although this will be a welcome addition to endarterectomy in the armamentarium of therapeutic options for patients with carotid disease, several challenges lie ahead. Coverage and reimbursement for the carotid stenting has been severely restricted to include only those procedures performed as part of an FDA investigational device exemption trial protocol, and a national noncoverage decision will have to be reckoned with before broader coverage can be put into place (assuming FDA approval). In addition, the level of national expertise in carotid endovascular intervention is limited, and training will need to be tailored to the three specialties likely to perform the procedure: cardiology, radiology, and vascular surgery. Each of these specialties will have specific, and different, requirements for their training, further complicating the task of

  11. Stiffness Properties of Adventitia, Media, and Full Thickness Human Atherosclerotic Carotid Arteries in the Axial and Circumferential Directions.

    Science.gov (United States)

    Hoffman, Allen H; Teng, Zhongzhao; Zheng, Jie; Wu, Zheyang; Woodard, Pamela K; Billiar, Kristen L; Wang, Liang; Tang, Dalin

    2017-12-01

    Arteries can be considered as layered composite material. Experimental data on the stiffness of human atherosclerotic carotid arteries and their media and adventitia layers are very limited. This study used uniaxial tests to determine the stiffness (tangent modulus) of human carotid artery sections containing American Heart Association type II and III lesions. Axial and circumferential oriented adventitia, media, and full thickness specimens were prepared from six human carotid arteries (total tissue strips: 71). Each artery yielded 12 specimens with two specimens in each of the following six categories; axial full thickness, axial adventitia (AA), axial media (AM), circumferential full thickness, circumferential adventitia (CA), and circumferential media (CM). Uniaxial testing was performed using Inspec 2200 controlled by software developed using labview. The mean stiffness of the adventitia was 3570 ± 667 and 2960 ± 331 kPa in the axial and circumferential directions, respectively, while the corresponding values for the media were 1070 ± 186 and 1800 ± 384 kPa. The adventitia was significantly stiffer than the media in both the axial (p = 0.003) and circumferential (p = 0.010) directions. The stiffness of the full thickness specimens was nearly identical in the axial (1540 ± 186) and circumferential (1530 ± 389 kPa) directions. The differences in axial and circumferential stiffness of media and adventitia were not statistically significant.

  12. Evidence for shear stress-mediated dilation of the internal carotid artery in humans

    DEFF Research Database (Denmark)

    Carter, Howard Henry; Atkinson, Ceri L; Heinonen, Ilkka H A

    2016-01-01

    Increases in arterial carbon dioxide tension (hypercapnia) elicit potent vasodilation of cerebral arterioles. Recent studies have also reported vasodilation of the internal carotid artery during hypercapnia, but the mechanism(s) mediating this extracranial vasoreactivity are unknown. Hypercapnia ...

  13. Dynamics of motion of a clot through an arterial bifurcation: a finite element analysis

    Science.gov (United States)

    Abolfazli, Ehsan; Fatouraee, Nasser; Vahidi, Bahman

    2014-10-01

    Although arterial embolism is important as a major cause of brain infarction, little information is available about the hemodynamic factors which govern the path emboli tend to follow. A method which predicts the trajectory of emboli in carotid arteries would be of a great value in understanding ischemic attack mechanisms and eventually devising hemodynamically optimal techniques for prevention of strokes. In this paper, computational models are presented to investigate the motion of a blood clot in a human carotid artery bifurcation. The governing equations for blood flow are the Navier-Stokes formulations. To achieve large structural movements, the arbitrary Lagrangian-Eulerian formulation (ALE) with an adaptive mesh method was employed for the fluid domain. The problem was solved by simultaneous solution of the fluid and the structure equations. In this paper, the phenomenon was simulated under laminar and Newtonian flow conditions. The measured stress-strain curve obtained from ultrasound elasticity imaging of the thrombus was set to a Sussman-Bathe material model representing embolus material properties. Shear stress magnitudes in the inner wall of the internal carotid artery (ICA) were measured. High magnitudes of wall shear stress (WSS) occurred in the areas in which the embolus and arterial are in contact with each other. Stress distribution in the embolus was also calculated and areas prone to rapture were identified. Effects of embolus size and embolus density on its motion velocity were investigated and it was observed that an increase in either embolus size or density led to a reduction in movement velocity of the embolus. Embolus trajectory and shear stress from a simulation of embolus movement in a three-dimensional model with patient-specific carotid artery bifurcation geometry are also presented.

  14. Effect of aspirin and ticlopidine on platelet deposition in carotid atherosclerosis: assessment by indium-111 platelet scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Isaka, Y.; Kimura, K.; Etani, H.; Uehara, A.; Uyama, O.; Yoneda, S.; Kamada, T.; Kusunoki, M.

    1986-11-01

    The antiplatelet effects of aspirin and ticlopidine were studied by a dual-tracer method, using indium-111 labeled platelets and technetium-99m human serum albumin, in a group of 12 patients with suspected ischemic cerebrovascular disease. The magnitude of platelet accumulation at the carotid bifurcation was expressed as the ratio of radioactivity of indium-111 platelets deposited on the vascular wall to those circulating in the blood-pool (PAI, platelet accumulation index), 48 hr after injection of labeled platelets. PAI values were measured before (baseline studies) and after the antithrombotic therapies (aspirin studies: 325 mg bid for 22.3 +/- 1.3 days, ticlopidine studies: 100 mg tid for 21.8 +/- 2.1 days). At the baseline, the mean PAI value at 24 carotid bifurcations in the patient group was 15.7 +/- 15.3% (mean +/- S.D.) compared to -4.3 +/- 9.1 at 24 carotid bifurcations in 12 normal subjects (p less than 0.01). We defined the upper limit for a normal PAI (%) value to be +13.9, namely the mean PAI plus 2 SD for the carotid bifurcation in normal subjects and used this value for semiquantitative analysis. At the baseline, significant elevation of PAI (more than 13.9%; positive scintigram) was observed at 12 of 24 vessels, while 12 other regions were negative (less than 13.9%). In the lesions with positive scintigraphic results at the baseline, the mean PAI (%) value from the baseline, aspirin and ticlopidine studies was 29.5 +/- 7.0, 11.2 +/- 8.5 (p less than 0.01 versus baseline) and 21.4 +/- 21.3 (not significant from baseline), respectively.

  15. About Bifurcational Parametric Simplification

    CERN Document Server

    Gol'dshtein, V; Yablonsky, G

    2015-01-01

    A concept of "critical" simplification was proposed by Yablonsky and Lazman in 1996 for the oxidation of carbon monoxide over a platinum catalyst using a Langmuir-Hinshelwood mechanism. The main observation was a simplification of the mechanism at ignition and extinction points. The critical simplification is an example of a much more general phenomenon that we call \\emph{a bifurcational parametric simplification}. Ignition and extinction points are points of equilibrium multiplicity bifurcations, i.e., they are points of a corresponding bifurcation set for parameters. Any bifurcation produces a dependence between system parameters. This is a mathematical explanation and/or justification of the "parametric simplification". It leads us to a conjecture that "maximal bifurcational parametric simplification" corresponds to the "maximal bifurcation complexity." This conjecture can have practical applications for experimental study, because at points of "maximal bifurcation complexity" the number of independent sys...

  16. Dangerous Bifurcations Revisited

    Science.gov (United States)

    Avrutin, Viktor; Zhusubaliyev, Zhanybai T.; Saha, Arindam; Banerjee, Soumitro; Sushko, Irina; Gardini, Laura

    2016-12-01

    A dangerous border collision bifurcation has been defined as the dynamical instability that occurs when the basins of attraction of stable fixed points shrink to a set of zero measure as the parameter approaches the bifurcation value from either side. This results in almost all trajectories diverging off to infinity at the bifurcation point, despite the eigenvalues of the fixed points before and after the bifurcation being within the unit circle. In this paper, we show that similar bifurcation phenomena also occur when the stable orbit in question is of a higher periodicity or is chaotic. Accordingly, we propose a generalized definition of dangerous bifurcation suitable for any kind of attracting sets. We report two types of dangerous border collision bifurcations and show that, in addition to the originally reported mechanism typically involving singleton saddle cycles, there exists one more situation where the basin boundary is formed by a repelling closed invariant curve.

  17. Associations between Carotid Artery Plaque Score, Carotid Hemodynamics and Coronary Heart Disease

    Directory of Open Access Journals (Sweden)

    Huiping Zhang

    2015-11-01

    Full Text Available Background: The carotid artery plaque score (PS is an independent predictor of Coronary Heart Disease (CHD. This study aims to evaluate the combination of PS and carotid hemodynamics to predict CHD. Methods: A total of 476 patients who underwent carotid ultrasonography and coronary angiography were divided into two groups depending on the presence of CHD. PS, carotid intima-media thickness, and carotid blood flow were measured. Receiver operating characteristic curve analysis was performed to establish the best prediction model for CHD presence. Results: Age, sex, carotid intima-media thickness of internal carotid artery and carotid bifurcation, PS, peak systolic velocity (PSA of right internal carotid artery (RICA, and most resistance index data were significantly related with the presence of CHD. The area under the curve for a collective model, which included factors of the PS, carotid hemodynamics and age, was significantly higher than the other model. Age, PS, and PSA of RICA were significant contributors for predicting CHD presence. Conclusions: The model of PS and PSA of RICA has greater predictive value for CHD than PS alone. Adding age to PS and PSA of RICA further improves predictive value over PS alone.

  18. Associations between Carotid Artery Plaque Score, Carotid Hemodynamics and Coronary Heart Disease

    Science.gov (United States)

    Zhang, Huiping; Liu, Mengxue; Ren, Tiantian; Wang, Xiangqian; Liu, Dandan; Xu, Mingliang; Han, LingFei; Wu, Zewei; Li, Haibo; Zhu, Yu; Wen, Yufeng; Sun, Wenjie

    2015-01-01

    Background: The carotid artery plaque score (PS) is an independent predictor of Coronary Heart Disease (CHD). This study aims to evaluate the combination of PS and carotid hemodynamics to predict CHD. Methods: A total of 476 patients who underwent carotid ultrasonography and coronary angiography were divided into two groups depending on the presence of CHD. PS, carotid intima-media thickness, and carotid blood flow were measured. Receiver operating characteristic curve analysis was performed to establish the best prediction model for CHD presence. Results: Age, sex, carotid intima-media thickness of internal carotid artery and carotid bifurcation, PS, peak systolic velocity (PSA) of right internal carotid artery (RICA), and most resistance index data were significantly related with the presence of CHD. The area under the curve for a collective model, which included factors of the PS, carotid hemodynamics and age, was significantly higher than the other model. Age, PS, and PSA of RICA were significant contributors for predicting CHD presence. Conclusions: The model of PS and PSA of RICA has greater predictive value for CHD than PS alone. Adding age to PS and PSA of RICA further improves predictive value over PS alone. PMID:26569275

  19. Bifurcation and Nonlinear Oscillations.

    Science.gov (United States)

    1980-09-28

    Structural stability and bifurcation theory. pp. 549-560 in Dinamical Systems (Ed. MI. Peixoto), Academic Press, 1973. [211 J. Sotomayor, Generic one...the specific structure of the bifurcation near the homo- clinic orbit. Near the Hopf bifurcation, our results could also be obtained from known...on U which maps orbits of f onto orbits of g preserving the sense of time. An f E9 is structurally stable if there is a neighborhood U of f such that

  20. [Diagnostic and treatment of carotid bodies tumors].

    Science.gov (United States)

    Tonev, A; Zakhariev, T

    2007-01-01

    Carotid body tumor is rare neoplasm (about 0,5 per cent of all tumors).[28]. The tumor arise from paraganglionic cells of carotid body, which develops from both mesodermal elements of the third branchial arch and neural elements originating from the neural crest ectoderm.[25]. Mathews warned: "this rare tumor presents unusual difficulties to the surgeon, and should one encounter it without having suspected the diagnosis, the experience will not soon be forgotten".[19]. The aim of this retrospective study is to investigate the frequency, number of spreading and results from the treatment in patients with carotid bodies tumors. Eleven patients (2,58%) with carotid bodies tumors were diagnosed and operated under upon from January 1990 to June 2007 at the "Department of Vascular surgery and Angiology" of "St. Ekaterina" University hospital - Sofia, from commonly 427 surgical intervention in the area of carotid triangle for the same period. The clinical picture, operating time and blood loss during the surgery were examined. Careful subadventitial dissection was used like a method, which have to reduce the number of postoperative complications and blood loss. All 11 patients were operated upon with endotrachial anesthesia and in two of them there was intracranial nerves injure, reconstruction of carotid artery has established in two of the patients. In the early postoperative period there was disphagia in three of the patients, four were with partial damage of n. hypoglossus, two- with damage of the face branch of n. facialis and six with parasthesia at the operated side. CT angiography of carotid bifurcation has established as basic method in the diagnostic. Total extirpation of the tumor remains the basic method of treatment from high quality specialists in carotid surgery. Careful subadvetitial dissection and accuracy excision allow the whole separation of the tumor from the carotid bifurcation without traumatic lesion. [28].

  1. Resetting of the carotid arterial baroreflex during dynamic exercise in humans

    DEFF Research Database (Denmark)

    Norton, K H; Boushel, Robert Christopher; Andersen, Line Strange

    1999-01-01

    Recent investigations have demonstrated that at the onset of low-to-moderate-intensity leg cycling exercise (L) the carotid baroreflex (CBR) was classically reset in direct relation to the intensity of exercise. On the basis of these data, we proposed that the CBR would also be classically reset ...

  2. Bifurcation without parameters

    CERN Document Server

    Liebscher, Stefan

    2015-01-01

    Targeted at mathematicians having at least a basic familiarity with classical bifurcation theory, this monograph provides a systematic classification and analysis of bifurcations without parameters in dynamical systems. Although the methods and concepts are briefly introduced, a prior knowledge of center-manifold reductions and normal-form calculations will help the reader to appreciate the presentation. Bifurcations without parameters occur along manifolds of equilibria, at points where normal hyperbolicity of the manifold is violated. The general theory, illustrated by many applications, aims at a geometric understanding of the local dynamics near the bifurcation points.

  3. Early control of distal internal carotid artery during carotid endarterectomy: does it reduce cerebral microemboli?

    Science.gov (United States)

    Mommertz, G; Das, M; Langer, S; Koeppel, T A; Krings, T; Mess, W H; Schiefer, J; Jacobs, M J

    2010-06-01

    According to the results of the large trials on carotid endarterectomy (CEA), this type of surgery is only warranted if perioperative mortality and morbidity are kept considerably low. Less attention has been paid to methods of cerebral protection during CEA, although intraoperative transcranial Doppler (TCD) can visualise intracerebral microemboli (MES) during routine carotid dissection, although MES occur throughout the CEA, only those during dissection are related to neurological outcome. Prevention of MES by means of early control of the distal internal carotid artery dislodging from the carotid artery plaque during dissection is very likely the mechanism behind an eventual benefit from this approach. Hence, the amount of MES might serve as a surrogate parameter for the risk of periprocedural neurological events. So, the aim of the present study was to evaluate whether early control of the distal carotid artery during CEA is capable of reducing the number of MES by means of a prospective randomised trial. Twenty-eight patients (29 procedures) could be prospectively included in our study. Before surgery we randomly assigned the patients to two groups: group A (N.=12): CEA by means of early control of the distal internal carotid artery; group B (N.=17): CEA with dissection of the total carotid bifurcation before clamping the arteries. Periprocedurally, we continuously monitored the cerebral blood flow in the ipsilateral middle cerebral artery by means of TCD. Pre- and postoperative morbidity were independently verified by a neurologist control of the distal internal carotid artery did not reduce the occurrence of MES during dissection of the carotid bifurcation. Also, the total number of MES throughout the procedure and postoperatively was comparable between both groups. The procedure related times as well as the clinical outcome did not differ significantly. Thus, early control of the distal internal carotid artery has got no advantage but also no disadvantage

  4. Long-term use of first-line highly active antiretroviral therapy is not associated with carotid artery stiffness in human immunodeficiency virus-positive patients

    Directory of Open Access Journals (Sweden)

    Haohui Zhu

    2014-09-01

    Conclusion: The first-line highly active antiretroviral therapy currently used in China is not associated with carotid artery stiffness in human immunodeficiency virus-positive patients with good highly active antiretroviral therapy compliance. Human immunodeficiency virus may play a role in the development of atherosclerosis.

  5. Increased Vascularization in the Vulnerable Upstream Regions of Both Early and Advanced Human Carotid Atherosclerosis.

    Directory of Open Access Journals (Sweden)

    Ola Hjelmgren

    Full Text Available Vascularization of atherosclerotic plaques has been linked to plaque vulnerability. The aim of this study was to test if the vascularization was increased in upstream regions of early atherosclerotic carotid plaques and also to test if the same pattern of vascularization was seen in complicated, symptomatic plaques.We enrolled 45 subjects with early atherosclerotic lesions for contrast enhanced ultrasound and evaluated the percentage of plaque area in a longitudinal ultrasound section which contained contrast agent. Contrast-agent uptake was evaluated in both the upstream and downstream regions of the plaque. We also collected carotid endarterectomy specimens from 56 subjects and upstream and downstream regions were localized using magnetic resonance angiography and analyzed using histopathology and immunohistochemistry.Vascularization was increased in the upstream regions of early carotid plaques compared with downstream regions (30% vs. 23%, p = 0.033. Vascularization was also increased in the upstream regions of advanced atherosclerotic lesions compared with downstream regions (4.6 vs. 1.4 vessels/mm2, p = 0.001 and was associated with intra-plaque hemorrhage and inflammation.Vascularization is increased in the upstream regions of both early and advanced plaques and is in advanced lesions mainly driven by inflammation.

  6. Differential mechanical response and microstructural organization between non-human primate femoral and carotid arteries

    Science.gov (United States)

    Raykin, Julia; Li, Haiyan; Gleason, Rudolph L.

    2014-01-01

    Unique anatomic locations and physiologic functions predispose different arteries to varying mechanical responses and pathologies. However, the underlying causes of these mechanical differences are not well understood. The objective of this study was to first identify structural differences in the arterial matrix that would account for the mechanical differences between healthy femoral and carotid arteries and second to utilize these structural observations to perform a microstructurally motivated constitutive analysis. Femoral and carotid arteries were subjected to cylindrical biaxial loading and their microstructure was quantified using two-photon microscopy. The femoral arteries were found to be less compliant than the carotid arteries at physiologic loads, consistent with previous studies, despite similar extracellular compositions of collagen and elastin (P > 0.05). The femoral arteries exhibited significantly less circumferential dispersion of collagen fibers (P arteries. Elastin transmural distribution, in vivo axial stretch, and opening angles were also found to be distinctly different between the arteries. Lastly, we modeled the arteries’ mechanical behaviors using a microstructural-based, distributed collagen fiber constitutive model. With this approach, the material parameters of the model were solved using the experimental microstructural observations. The findings of this study support an important role for microstructural organization in arterial stiffness. PMID:24532266

  7. A comparative study of CFD of canine model of common carotid fusiform aneurysm and vertebrobasilar fusiform aneurysm in human patients.

    Science.gov (United States)

    Guo, Shewei; Jiang, Peng; Liu, Jian; Yang, Xinjian; Jiang, Chuhan; Li, Youxiang; Wu, Zhongxue

    2017-09-22

    Intracranial fusiform aneurysm (IFA) is a relatively uncommon subgroup of aneurysms. There are few reports that focus on the hemodynamics of IFA. In this study, we compared the hemodynamics of the canine model of common carotid fusiform aneurysm and vertebrobasilar fusiform aneurysms in human patients. Five male mongrel dogs were randomly chosen, and there unilateral common carotid artery (CCA) and external jugular vein were surgically exposed individually. The CCA was transected and interposed by the free segment of the external jugular vein through end-to-end anastomosis to form a fusiform aneurysm. 3D digital substraction angiography data of each dog's and five randomly chosen male patients' vertebrobasilar fusiform aneurysms were obtained and then analysed by computational fluid dynamics software. The morphological and hemodynamic parameters were compared between the dogs and the patients. The morphological and hemodynamic parameters of the fusiform aneurysms were similar between the dogs and the patients. However, the hemodynamics was more complex in the patients. The canine fusiform aneurysm model exhibits high similarity in morphology and hemodynamics with human patients'. Therefore, this model can be used to study the fluid-solid interaction in the aneurysm and to explore the underlying mechanisms of the development, rupture and occurrence of IFAs, which offers a pathophysiological tool to seek better treatments of IFAs.

  8. Comparison of grey scale median (GSM) measurement in ultrasound images of human carotid plaques using two different softwares.

    Science.gov (United States)

    Östling, Gerd; Persson, Margaretha; Hedblad, Bo; Gonçalves, Isabel

    2013-11-01

    Grey scale median (GSM) measured on ultrasound images of carotid plaques has been used for several years now in research to find the vulnerable plaque. Centres have used different software and also different methods for GSM measurement. This has resulted in a wide range of GSM values and cut-off values for the detection of the vulnerable plaque. The aim of this study was to compare the values obtained with two different softwares, using different standardization methods, for the measurement of GSM on ultrasound images of carotid human plaques. GSM was measured with Adobe Photoshop(®) and with Artery Measurement System (AMS) on duplex ultrasound images of 100 consecutive medium- to large-sized carotid plaques of the Beta-blocker Cholesterol-lowering Asymptomatic Plaque Study (BCAPS). The mean values of GSM were 35·2 ± 19·3 and 55·8 ± 22·5 for Adobe Photoshop(®) and AMS, respectively. Mean difference was 20·45 (95% CI: 19·17-21·73). Although the absolute values of GSM differed, the agreement between the two measurements was good, correlation coefficient 0·95. A chi-square test revealed a kappa value of 0·68 when studying quartiles of GSM. The intra-observer variability was 1·9% for AMS and 2·5% for Adobe Photoshop. The difference between softwares and standardization methods must be taken into consideration when comparing studies. To avoid these problems, researcher should come to a consensus regarding software and standardization method for GSM measurement on ultrasound images of plaque in the arteries. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  9. Carotid artery surgery

    Science.gov (United States)

    Carotid endarterectomy; CAS surgery; Carotid artery stenosis - surgery; Endarterectomy - carotid artery ... results of stenting versus endarterectomy for carotid-artery stenosis. N Engl J Med . 2016;374(11):1021- ...

  10. Segment-specific carotid intima-media thickness and cardiovascular risk factors in Koreans: the Healthy Twin Study.

    Science.gov (United States)

    Lee, Kayoung; Sung, Joohon; Lee, Sang Cheol; Park, Seung Woo; Kim, Youn Sic; Lee, Joo Yeon; Ebrahim, Shah; Song, Yun-Mi

    2012-10-01

    Increased carotid intima-media thickness is associated with higher cardiovascular disease risk. This study aimed to evaluate the contributions of cardiovascular risk factors and inheritance to segment-specific carotid intima-media thickness. Cross-sectional observational study. A total of 706 Korean adults was selected from the Healthy Twin Study. The intima-media thickness of common, carotid bifurcation, and internal carotid artery were measured using B-mode ultrasound. Behavioral and biological cardiovascular risk factors were measured. Quantitative genetic and linear mixed analyses were performed to examine inherited and environmental contributions to intima-media thickness variation. Heritability of intima-media thickness was moderately high with estimates (95% confidence intervals) of 0.48 (0.37, 0.59), 0.38(0.27, 0.49), and 0.45(0.34, 0.55) for common, carotid bifurcation, and internal carotid artery, respectively. The additive genetic cross-trait correlations between the segments ranged between 0.43 and 0.75, suggesting a shared genetic influence on the three carotid segments. Additive inherited effects contributed 21% and 31% (common and internal carotid, respectively) to the total variance of the intima-media thickness, while measured cardiovascular risk factors accounted for 46% and 26% (common and internal carotid, respectively). The cardiovascular risk factors significantly associated with carotid intima-media thickness were as follows: in men, alcohol use (bifurcation); physical activity (common and internal); BMI (all segments); diabetes (bifurcation and internal); hypertension (internal); and HDL-cholesterol (common and bifurcation); and in women, smoking (bifurcation), hypertension (common), total and LDL cholesterol (bifurcation and internal), and hs-CRP (common and internal). Individual cardiovascular risk factors were differentially associated with carotid intima-media thickness by segments and sex. Inherited effects made a heterogeneous

  11. Treatment of a symptomatic intrathoracic internal carotid artery

    Directory of Open Access Journals (Sweden)

    Christopher R. Brown

    2017-09-01

    Full Text Available Intrathoracic common carotid artery bifurcations are an anatomic anomaly with such rarity that only six cases have been reported to date. The true incidence of and preferred treatment options for a diseased intrathoracic common carotid artery bifurcation or internal carotid artery (ICA have not been clearly described. This case report describes a 72-year-old man who experienced a postoperative right hemispheric stoke after an aortic valve replacement, radiofrequency maze procedure, and left atrial appendage clip. Postoperative cerebrovascular evaluation revealed a severely diseased intrathoracic ICA that was treated by ligation of the diseased proximal ICA and transposition of the distal ICA to the disease-free external carotid artery. The patient provided written consent to present the history, data, and images in this manuscript.

  12. Carotid baroreceptor stimulation blood pressure response mapped in patients undergoing carotid endarterectomy (C-Map study).

    Science.gov (United States)

    Kansal, Nikhil; Clair, Daniel G; Jaye, Deborah A; Scheiner, Avram

    2016-12-01

    Continuous stimulation of the carotid baroreceptors has been shown to evoke a sustained systolic blood pressure (SBP) reduction in hypertensive subjects. This study conducted a detailed mapping of the SBP and heart rate response to electrical stimulus at different locations in the carotid sinus region in patients undergoing a carotid endarterectomy (CEA). The Carotid Sinus Autonomic Response Mapping (C-Map) Study is a multicenter, prospective, non-randomized, acute feasibility study conducted in 10 hypertensive subjects undergoing CEA. Electrode pairs were placed in multiple locations in the region of the carotid sinus for acute stimulation, and the tests were repeated after plaque removal and vessel repair. The configuration that elicited the largest pressure reduction in 8 of 10 patients was with the electrodes arranged longitudinally along the medial (in relation to the bifurcation) wall of the internal carotid artery (ICA) near the bifurcation (11.2±8.1mmHg, pEndarterectomy surgery did not affect maximal acute stimulation response but improved baroreflex sensitivity acutely. Acute extravascular baroreceptor stimulation (BRS) mapping demonstrated that blood pressure reductions are dependent on electrode location and orientation. In most subjects, the largest SBP reductions were elicited in the region of the medial wall of the ICA. This area can be targeted for future BRS lead design and implant. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Relative Lyapunov Center Bifurcations

    DEFF Research Database (Denmark)

    Wulff, Claudia; Schilder, Frank

    2014-01-01

    Relative equilibria (REs) and relative periodic orbits (RPOs) are ubiquitous in symmetric Hamiltonian systems and occur, for example, in celestial mechanics, molecular dynamics, and rigid body motion. REs are equilibria, and RPOs are periodic orbits of the symmetry reduced system. Relative Lyapunov...... center bifurcations are bifurcations of RPOs from REs corresponding to Lyapunov center bifurcations of the symmetry reduced dynamics. In this paper we first prove a relative Lyapunov center theorem by combining recent results on the persistence of RPOs in Hamiltonian systems with a symmetric Lyapunov...

  14. Endogenous Cholesterol Excretion Is Negatively Associated With Carotid Intima-Media Thickness in Humans.

    Science.gov (United States)

    Lin, Xiaobo; Racette, Susan B; Ma, Lina; Wallendorf, Michael; Dávila-Román, Victor G; Ostlund, Richard E

    2017-12-01

    Epidemiological studies strongly suggest that lipid factors independent of low-density lipoprotein cholesterol contribute significantly to cardiovascular disease risk. Because circulating lipoproteins comprise only a small fraction of total body cholesterol, the mobilization and excretion of cholesterol from plasma and tissue pools may be an important determinant of cardiovascular disease risk. Our hypothesis is that fecal excretion of endogenous cholesterol is protective against atherosclerosis. Cholesterol metabolism and carotid intima-media thickness were quantitated in 86 nondiabetic adults. Plasma cholesterol was labeled by intravenous infusion of cholesterol-d 7 solubilized in a lipid emulsion and dietary cholesterol by cholesterol-d 5 and the nonabsorbable stool marker sitostanol-d 4 . Plasma and stool samples were collected while subjects consumed a cholesterol- and phytosterol-controlled metabolic kitchen diet and were analyzed by mass spectrometry. Carotid intima-media thickness was negatively correlated with fecal excretion of endogenous cholesterol ( r =-0.426; P cholesterol ( r =-0.472; P ≤0.0001), and daily percent excretion of cholesterol from the rapidly mixing cholesterol pool ( r =-0.343; P =0.0012) and was positively correlated with percent cholesterol absorption ( r =+0.279; P =0.0092). In a linear regression model controlling for age, sex, systolic blood pressure, hemoglobin A1c, low-density lipoprotein, high-density lipoprotein cholesterol, and statin drug use, fecal excretion of endogenous cholesterol remained significant ( P =0.0008). Excretion of endogenous cholesterol is strongly, independently, and negatively associated with carotid intima-media thickness. The reverse cholesterol transport pathway comprising the intestine and the rapidly mixing plasma, and tissue cholesterol pool could be an unrecognized determinant of cardiovascular disease risk not reflected in circulating lipoproteins. Further work is needed to relate measures of

  15. Data on consistency among different methods to assess atherosclerotic plaque echogenicity on standard ultrasound and intraplaque neovascularization on contrast-enhanced ultrasound imaging in human carotid artery

    Directory of Open Access Journals (Sweden)

    Mattia Cattaneo

    2016-12-01

    Full Text Available Here we provide the correlation among different carotid ultrasound (US variables to assess echogenicity n standard carotid US and to assess intraplaque neovascularization on contrast enhanced US. We recruited 45 consecutive subjects with an asymptomatic≥50% carotid artery stenosis. Carotid plaque echogenicity at standard US was visually graded according to Gray–Weale classification (GW and measured by the greyscale median (GSM, a semi-automated computerized measurement performed by Adobe Photoshop®. On CEUS imaging IPNV was graded according to the visual appearance of contrast within the plaque according to three different methods: CEUS_A (1=absent; 2=present; CEUS_B a three-point scale (increasing IPNV from 1 to 3; CEUS_C a four-point scale (increasing IPNV from 0 to 3. We have also implemented a new simple quantification method derived from region of interest (ROI signal intensity ratio as assessed by QLAB software. Further information is available in “Contrast-enhanced ultrasound imaging of intraplaque neovascularization and its correlation to plaque echogenicity in human carotid arteries atherosclerosis (M. Cattaneo, D. Staub, A.P. Porretta, J.M. Gallino, P. Santini, C. Limoni et al., 2016 [1].

  16. Unusual looping of the internal carotid artery in relation to an enlarged lymph node

    Directory of Open Access Journals (Sweden)

    Nayak SB

    2010-06-01

    Full Text Available Knowledge of variations of internal carotid artery is important to surgeons doing head and neck surgery as well as to radiologists doing imaging and invasive techniques. In the current case, the right internal carotid artery showed a characteristic loop at its beginning. An abnormal, enlarged lymph node was found at the carotid bifurcation, which was projecting into the loop. The left internal carotid artery was normal. The unusual looping of internal carotid artery at its beginning might result in altered blood flow to the brain and may lead to confusions in surgical, imaging and invasive techniques.

  17. Numerical Bifurcation Analysis

    NARCIS (Netherlands)

    Meijer, Hil Gaétan Ellart; Dercole, Fabio; Oldeman, Bart; Myers, R.A.

    The theory of dynamical systems studies the behavior of solutions of systems, like nonlinear ordinary differential equations (ODEs), depending upon parameters. Using qualitative methods of bifurcation theory, the behavior of the system is characterized for various parameter combinations. In

  18. Pathology of Human Coronary and Carotid Artery Atherosclerosis and Vascular Calcification in Diabetes Mellitus.

    Science.gov (United States)

    Yahagi, Kazuyuki; Kolodgie, Frank D; Lutter, Christoph; Mori, Hiroyoshi; Romero, Maria E; Finn, Aloke V; Virmani, Renu

    2017-02-01

    The continuing increase in the prevalence of diabetes mellitus in the general population is predicted to result in a higher incidence of cardiovascular disease. Although the mechanisms of diabetes mellitus-associated progression of atherosclerosis are not fully understood, at clinical and pathological levels, there is an appreciation of increased disease burden and higher levels of arterial calcification in these subjects. Plaques within the coronary arteries of patients with diabetes mellitus generally exhibit larger necrotic cores and significantly greater inflammation consisting mainly of macrophages and T lymphocytes relative to patients without diabetes mellitus. Moreover, there is a higher incidence of healed plaque ruptures and positive remodeling in hearts from subjects with type 1 diabetes mellitus and type 2 diabetes mellitus, suggesting a more active atherogenic process. Lesion calcification in the coronary, carotid, and other arterial beds is also more extensive. Although the role of coronary artery calcification in identifying cardiovascular disease and predicting its outcome is undeniable, our understanding of how key hormonal and physiological alterations associated with diabetes mellitus such as insulin resistance and hyperglycemia influence the process of vascular calcification continues to grow. Important drivers of atherosclerotic calcification in diabetes mellitus include oxidative stress, endothelial dysfunction, alterations in mineral metabolism, increased inflammatory cytokine production, and release of osteoprogenitor cells from the marrow into the circulation. Our review will focus on the pathophysiology of type 1 diabetes mellitus- and type 2 diabetes mellitus-associated vascular disease with particular focus on coronary and carotid atherosclerotic calcification. © 2016 American Heart Association, Inc.

  19. Attenuation of human carotid-cardiac vagal baroreflex responses after physical detraining

    Science.gov (United States)

    Convertino, Victor A.; Fritsch, Janice M.

    1992-01-01

    Astronauts who are occupied with prelaunch schedules may have to limit their regular physical exercise routines. To assess a potential effect on blood pressure control, carotid baroreceptor-cardiac reflex responses of 16 men were evaluated before and after two weeks of exercise detraining that followed ten weeks of regular scheduled exercise (30 min/d, 4 d/week at 75 percent V(O2) max). After detraining, the baroreflex stimulus-response relationship had a reduced slope 0.4 msec/mmHg and range of response. In addition, there was a resetting of the relationship on the R-R interval axis. Both the minimum and maximum R-R interval responses to the stimulus were significantly reduced after detraining. Baseline systolic pressure did not change with detraining, and the carotid baroreceptor-cardiac response relationship did not shift on the pressure axis. These results suggest that detraining from regular exercise can compromise vagally-mediated mechanisms of blood pressure regulation.

  20. Análisis de la variación del flujo sanguíneo en la bifurcación carótida con diferentes grados de estenosamiento, utilizando MEF. // Analysis of the blood flow rate variation at the carotid bifurcation with different stenosis levels, using FEM.

    Directory of Open Access Journals (Sweden)

    G. Vilalta

    2008-05-01

    section of the arteries as a result of lipid deposit in the inner layer of the vessel. Thepresent paper studies the influence of the blood viscosity in the flow at the carotid bifurcation through the numericalmodeling. The study was carried out for three stenosis levels, (SS=30, 60 and 75 % and five viscosity values, (3,5 cP, 7 cP,20 cP, 35 cP, 50 cP.The results obtained show a significant reduction in the blood flow for viscosities increasing up to 7cP. For greater viscosities values the system flow remains constant, which is consistent with the medical practice.Key words: Fluid dynamic, polymer addition, finite element formulation, carotid bifurcation.

  1. Plasticity of central chemoreceptors: effect of bilateral carotid body resection on central CO2 sensitivity.

    Directory of Open Access Journals (Sweden)

    Albert Dahan

    2007-07-01

    Full Text Available Human breathing is regulated by feedback and feed-forward control mechanisms, allowing a strict matching between metabolic needs and the uptake of oxygen in the lungs. The most important control mechanism, the metabolic ventilatory control system, is fine-tuned by two sets of chemoreceptors, the peripheral chemoreceptors in the carotid bodies (located in the bifurcation of the common carotid arteries and the central CO2 chemoreceptors in the ventral medulla. Animal data indicate that resection of the carotid bodies results, apart from the loss of the peripheral chemoreceptors, in reduced activity of the central CO2 sensors. We assessed the acute and chronic effect of carotid body resection in three humans who underwent bilateral carotid body resection (bCBR after developing carotid body tumors.The three patients (two men, one woman were suffering from a hereditary form of carotid body tumors. They were studied prior to surgery and at regular intervals for 2-4 y following bCBR. We obtained inspired minute ventilation (Vi responses to hypoxia and CO2. The Vi-CO2 responses were separated into a peripheral (fast response and a central (slow response with a two-compartment model of the ventilatory control system. Following surgery the ventilatory CO2 sensitivity of the peripheral chemoreceptors and the hypoxic responses were not different from zero or below 10% of preoperative values. The ventilatory CO2 sensitivity of the central chemoreceptors decreased by about 75% after surgery, with peak reduction occurring between 3 and 6 mo postoperatively. This was followed by a slow return to values close to preoperative values within 2 y. During this slow return, the Vi-CO2 response shifted slowly to the right by about 8 mm Hg.The reduction in central Vi-CO2 sensitivity after the loss of the carotid bodies suggests that the carotid bodies exert a tonic drive or tonic facilitation on the output of the central chemoreceptors that is lost upon their resection

  2. Plasticity of central chemoreceptors: effect of bilateral carotid body resection on central CO2 sensitivity.

    Science.gov (United States)

    Dahan, Albert; Nieuwenhuijs, Diederik; Teppema, Luc

    2007-07-24

    Human breathing is regulated by feedback and feed-forward control mechanisms, allowing a strict matching between metabolic needs and the uptake of oxygen in the lungs. The most important control mechanism, the metabolic ventilatory control system, is fine-tuned by two sets of chemoreceptors, the peripheral chemoreceptors in the carotid bodies (located in the bifurcation of the common carotid arteries) and the central CO2 chemoreceptors in the ventral medulla. Animal data indicate that resection of the carotid bodies results, apart from the loss of the peripheral chemoreceptors, in reduced activity of the central CO2 sensors. We assessed the acute and chronic effect of carotid body resection in three humans who underwent bilateral carotid body resection (bCBR) after developing carotid body tumors. The three patients (two men, one woman) were suffering from a hereditary form of carotid body tumors. They were studied prior to surgery and at regular intervals for 2-4 y following bCBR. We obtained inspired minute ventilation (Vi) responses to hypoxia and CO2. The Vi-CO2 responses were separated into a peripheral (fast) response and a central (slow) response with a two-compartment model of the ventilatory control system. Following surgery the ventilatory CO2 sensitivity of the peripheral chemoreceptors and the hypoxic responses were not different from zero or below 10% of preoperative values. The ventilatory CO2 sensitivity of the central chemoreceptors decreased by about 75% after surgery, with peak reduction occurring between 3 and 6 mo postoperatively. This was followed by a slow return to values close to preoperative values within 2 y. During this slow return, the Vi-CO2 response shifted slowly to the right by about 8 mm Hg. The reduction in central Vi-CO2 sensitivity after the loss of the carotid bodies suggests that the carotid bodies exert a tonic drive or tonic facilitation on the output of the central chemoreceptors that is lost upon their resection. The

  3. Prevention of Intra-operative Cerebral Ischemia during Carotid Endarterectomy, Loco-regional versus General Anesthesia

    Science.gov (United States)

    Tawfic, Qutaiba A.; Ismaili, Mohamed Al; Ahmed, Mooyad A.

    2012-01-01

    Carotid endarterectomy (CEA), as a prophylactic operation is becoming more popular. It is performed in patients who are at risk of stroke from dislodged atheromatous plaque at the carotid bifurcation. The major concern during CEA is the detection of cerebral hypoperfusion or ischemia during carotid cross clamping. Some studies have shown that the introduction of loco-regional anesthesia has lowered the incidence of major complications compared with general anesthesia since ischemia detection is easier in conscious patient. PMID:22811781

  4. Stenotic lesion level did not affect outcomes of carotid endarterectomy.

    Science.gov (United States)

    Suhara, Masamitsu; Hoshina, Katsuyuki; Akai, Atsushi; Isaji, Toshihiko; Akagi, Daisuke; Yamamoto, Kota; Miyahara, Takuya; Watanabe, Toshiaki

    2017-05-01

    Background Carotid endarterectomy is the established treatment for carotid artery stenosis, and remains the primary surgical option due to its superior outcomes compared to carotid arterial stenting. However, Japanese patients are known to have unfavorable anatomical conditions for carotid endarterectomy, with a relatively higher level of the carotid artery bifurcation than in the Western population. We investigated the outcomes of carotid endarterectomy in our institute and evaluated the procedural quality by comparing patients based on higher or lower lesion levels. Methods The clinical data of 65 patients who underwent carotid endarterectomy were collected retrospectively. The outcomes reviewed included stroke-free survival and stroke-free rate. The patients were divided into a higher group ( n = 25) and a lower group ( n = 40), based on lesion location in respect of the 2nd cervical vertebral level. Results There was no perioperative death and only one case of stroke in the higher group within 30 days after carotid endarterectomy. At 5 years after carotid endarterectomy, the stroke-free survival rates were 83.4% in the higher group and 87.8% in the lower group, while the stroke-free rates were 96.0% and 94.0%, respectively; there were no significant differences between groups. Conclusions Stenotic lesion level did not affect the outcome or procedural quality of carotid endarterectomy.

  5. Temporal dependence of in vivo USPIO-enhanced MRI signal changes in human carotid atheromatous plaques

    Energy Technology Data Exchange (ETDEWEB)

    Tang, T.Y.; Sadat, U. [Cambridge University Hospitals NHS Foundation Trust, University Department of Radiology, Cambridge (United Kingdom); Cambridge University Hospitals NHS Foundation Trust, Cambridge Vascular Unit, Cambridge (United Kingdom); Patterson, A.J.; Graves, M.J.; Howarth, S.P.S.; U-King-Im, J.M.; Li, Z.Y.; Young, V.E.; Gillard, J.H. [Cambridge University Hospitals NHS Foundation Trust, University Department of Radiology, Cambridge (United Kingdom); Miller, S.R. [GlaxoSmithKline, Biostatistics and Data Sciences, Harlow (United Kingdom); Walsh, S.R.; Boyle, J.R.; Gaunt, M.E. [Cambridge University Hospitals NHS Foundation Trust, Cambridge Vascular Unit, Cambridge (United Kingdom)

    2009-07-15

    Ultrasmall superparamagnetic iron oxide (USPIO)-enhanced MRI has been shown to be a useful modality to image activated macrophages in vivo, which are principally responsible for plaque inflammation. This study determined the optimum imaging time-window to detect maximal signal change post-USPIO infusion using T{sub 1}-weighted (T{sub 1}w), T{sub 2}*-weighted (T{sub 2}*w) and quantitative T{sub 2}* (qT{sub 2}*) imaging. Six patients with an asymptomatic carotid stenosis underwent high resolution T{sub 1}w, T{sub 2}*w and qT{sub 2}* MR imaging of their carotid arteries at 1.5 T. Imaging was performed before and at 24, 36, 48, 72 and 96 h after USPIO (Sinerem trademark, Guerbet, France) infusion. Each slice showing atherosclerotic plaque was manually segmented into quadrants and signal changes in each quadrant were fitted to an exponential power function to model the optimum time for post-infusion imaging. The power function determining the mean time to convergence for all patients was 46, 41 and 39 h for the T{sub 1}w, T{sub 2}*w and qT{sub 2}* sequences, respectively. When modelling each patient individually, 90% of the maximum signal intensity change was observed at 36 h for three, four and six patients on T{sub 1}w, T{sub 2}*w and qT{sub 2}*, respectively. The rates of signal change decrease after this period but signal change was still evident up to 96 h. This study showed that a suitable imaging window for T{sub 1}w, T{sub 2}*w and qT{sub 2}* signal changes post-USPIO infusion was between 36 and 48 h. Logistically, this would be convenient in bringing patients back for one post-contrast MRI, but validation is required in a larger cohort of patients. (orig.)

  6. Expression of the vitamin K-dependent proteins GAS6 and protein S and the TAM receptor tyrosine kinases in human atherosclerotic carotid plaques.

    Science.gov (United States)

    Hurtado, B; Muñoz, X; Recarte-Pelz, P; García, N; Luque, A; Krupinski, J; Sala, N; García de Frutos, P

    2011-05-01

    The GAS6/ProS-TAM system is composed of two vitamin K-dependent ligands (GAS6 and protein S) and their three protein tyrosine kinase receptors TYRO3, AXL and MERTK, known as the TAM receptors. The system plays a prominent role in conditions of injury, inflammation and repair. In murine models of atherosclerotic plaque formation, mutations in its components affect atherosclerosis severity. Here we used Taqman low-density arrays and immunoblotting to study mRNA and protein expression of GAS6, ProS and the TAM receptors in human carotid arteries with different degrees of atherosclerosis. The results show a clear down-regulation of the expression of AXL in atheroma plaques with respect to normal carotids that is matched by decreased abundance of AXL in protein extracts detected by immunoblotting. A similar decrease was observed in PROS1 mRNA expression in atherosclerotic carotids compared to the normal ones, but in this case protein S (ProS) was clearly increased in protein extracts of carotid arteries with increasing grade of atherosclerosis, suggesting that ProS is carried into the plaque. MERTK was also increased in atherosclerotic carotid arteries with respect to the normal ones, suggesting that the ProS-MERTK axis is functional in advanced human atherosclerotic plaques. MERTK was expressed in macrophages, frequently in association with ProS, while ProS was abundant also in the necrotic core. Our data suggest that the ProS-MERTK ligand-receptor pair was active in advanced stages of atherosclerosis, while AXL signalling is probably down-regulated.

  7. Multiple cusp bifurcations.

    Science.gov (United States)

    Izhikevich, Eugene M.

    1998-04-01

    The cusp bifurcation provides one of the simplest routes leading to bistability and hysteresis in neuron dynamics. We show that weakly connected networks of neurons near cusp bifurcations that satisfy a certain adaptation condition have quite interesting and complicated dynamics. First, we prove that any such network can be transformed into a canonical model by an appropriate continuous change of variables. Then we show that the canonical model can operate as a multiple attractor neural network or as a globally asymptotically stable neural network depending on the choice of parameters.

  8. Influence of ageing on carotid baroreflex peak response latency in humans

    DEFF Research Database (Denmark)

    Fisher, J.P.; Kim, A.; Young, C.N.

    2009-01-01

    ) and older (61 +/- 1 years) subjects, using 5 s pulses of neck pressure (NP, +35 Torr) and neck suction (NS, -80 Torr). Second, CBR latency was assessed following pharmacological blockade of cardiac parasympathetic nerve activity in eight young subjects, to better understand how known age-related reductions......, little attention has been given to the influence of ageing on the latency of peak baroreflex responses. First, we compared the temporal pattern of heart rate (HR) and mean arterial blood pressure (BP) responses to selective carotid baroreceptor (CBR) unloading and loading in 14 young (22 +/- 1 years...... in parasympathetic nerve activity influence CBR response latency. In response to NP, the time to the peak increase in HR and mean BP were similar in young and older groups. In contrast, in response to NS the time to peak decrease in HR (2.1 +/- 0.2 vs. 3.8 +/- 0.2 s) and mean BP (6.7 +/- 0.4 vs. 8.3 +/- 0.2 s) were...

  9. Reduction in deposition of indium 111-labeled platelets after autologous endothelial cell seeding of Dacron aortic bifurcation grafts in humans: a preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    Ortenwall, P.; Wadenvik, H.; Kutti, J.; Risberg, B.

    1987-07-01

    Autologous endothelial seeding (AES) of vascular prostheses in dogs increases thrombus-free surface and improves prosthetic prostacyclin production, patency, and the ability to withstand hematogenous challenge with bacteria. No such information is available in human subjects. In the present study one limb of an aortic Dacron bifurcation prosthesis was seeded with autologous endothelial cells (ECs) harvested from the distal portion of the saphenous vein by enzymatic treatment. The deposition of indium 111-labeled platelets on the vascular prostheses was studied 1 and 4 months after operation. In seven of nine patients seeding resulted in decreased accumulation of radiolabeled platelets compared with sham-seeded control limbs (p less than 0.04), when studied 1 month after surgery. A decrease in platelet accumulation occurred over the whole prosthesis between 1 and 4 months, and no significant difference was noted at 4 months between seeded and nonseeded graft limbs. Although the seeding density was very low (440 ECs/cm2), the observed difference in platelet accumulation for AES-treated graft limbs in the early postoperative course merits further investigation of this technique in human beings.

  10. Bifurcation of Hyperbolic Planforms

    Science.gov (United States)

    Chossat, Pascal; Faye, Grégory; Faugeras, Olivier

    2011-02-01

    Motivated by a model for the perception of textures by the visual cortex in primates, we analyze the bifurcation of periodic patterns for nonlinear equations describing the state of a system defined on the space of structure tensors, when these equations are further invariant with respect to the isometries of this space. We show that the problem reduces to a bifurcation problem in the hyperbolic plane {D} (Poincaré disc). We make use of the concept of a periodic lattice in {D} to further reduce the problem to one on a compact Riemann surface {D}/\\varGamma, where Γ is a cocompact, torsion-free Fuchsian group. The knowledge of the symmetry group of this surface allows us to use the machinery of equivariant bifurcation theory. Solutions which generically bifurcate are called "H-planforms", by analogy with the "planforms" introduced for pattern formation in Euclidean space. This concept is applied to the case of an octagonal periodic pattern, where we are able to classify all possible H-planforms satisfying the hypotheses of the Equivariant Branching Lemma. These patterns are, however, not straightforward to compute, even numerically, and in the last section we describe a method for computation illustrated with a selection of images of octagonal H-planforms.

  11. Autotransplantation of human carotid body cell aggregates for treatment of Parkinson's disease.

    Science.gov (United States)

    Arjona, Ventura; Mínguez-Castellanos, Adolfo; Montoro, Rafael J; Ortega, Angel; Escamilla, Francisco; Toledo-Aral, Juan José; Pardal, Ricardo; Méndez-Ferrer, Simón; Martín, José M; Pérez, Miguel; Katati, Majed J; Valencia, Eduardo; García, Teresa; López-Barneo, José

    2003-08-01

    In this study, we assessed the feasibility of autotransplantation of carotid body (CB) cell aggregates into the striatum for the treatment of patients with Parkinson's disease (PD). Six patients with advanced PD underwent bilateral autotransplantation of CB cell aggregates into the striatum. They were evaluated clinically preoperatively and for 18 months after surgery according to the recommendations of the Core Assessment Program for Intracerebral Transplantation. No major complications or adverse events resulted from the cell implantation or surgical procedures. During the course of the study, there was no significant aggravation of dyskinesia or decline in cognitive function in any of the patients. Five of the six patients who underwent transplantation manifested a measurable degree of clinical improvement evidenced by standardized clinical rating scales for PD. A decrease in the blinded Unified Parkinson's Disease Rating Scale Part III in the "off" state, the main measure of transplant efficacy in our study, was found to be maximal (between 26 and 74%) at 6 months after surgery. At 1 year, clear reductions in the blinded Unified Parkinson's Disease Rating Scale Part III were maintained in three patients (24, 38, and 52%, respectively). Modest improvement was seen in two patients (13 and 17%), and the sole patient who showed no improvement had the most fibrosis in the CB. The age of the patient and the state of the CB tissue were adversely correlated with clinical improvement after CB autotransplantation. This pilot study indicates that CB autograft transplantation is a relatively simple, safe, and viable therapeutical approach for the treatment of patients with advanced PD. More studies are needed to optimize the procedure and to assess its general applicability for the treatment of patients with PD.

  12. Prevalence of carotid and pulp calcifications: a correlation using digital panoramic radiographs

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Stephen J. [School of Dentistry, University of Louisville, Department of Periodontics, Endodontics and Dental Hygiene, Louisville, KY (United States); Scheetz, James P.; Khan, Zafrulla [University of Louisville, Department of Diagnostic Sciences, Prosthodontics and Restorative Dentistry, School of Dentistry, Louisville, KY (United States); Farman, Allan G. [School of Dentistry, University of Louisville, Department of Periodontics, Endodontics and Dental Hygiene, Louisville, KY (United States); Horsley, Scott H.; Beckstrom, Brice

    2009-03-15

    To compare the prevalence of pulp calcification with that of carotid calcification using digital panoramic dental radiographs. Digital panoramic radiographs of patients at a dental oncology clinic were included if (1) the carotid artery bifurcation region was visible bilaterally and (2) the patient had non-restored or minimally restored molars and/or canines. An endodontist evaluated the images for pulpal calcifications in the selected teeth. An oral and maxillofacial radiologist independently evaluated the same images for calcifications in the carotid bifurcation region. Odds-ratio and Pearson {chi}{sup 2} were used for data analysis. Presence of pulpal calcification was also evaluated as a screening test for the presence of carotid calcification. A total of 247 panoramic radiographs were evaluated. 32% (n=80) had pulpal calcifications and 25% (n=61) had carotid calcifications with 12% (n=29) having both carotid and pulp calcifications. A significantly higher prevalence of both pulp and carotid calcification was found in subjects older than age 60 years compared to younger age groups. Accuracy of pulpal calcification in screening for carotid calcification was 66.4%. Both pulp and carotid calcifications were more prevalent in older individuals. The presence of pulp calcification was not a strong predictor for the presence of carotid calcification. (orig.)

  13. CD36 Is Significantly Correlated with Adipophilin in Human Carotid Lesions and Inversely Correlated with Plasma ApoAI

    Directory of Open Access Journals (Sweden)

    Sophie Collot-Teixeira

    2008-01-01

    Full Text Available OxLDL uptake and cholesterol efflux inhibition in macrophages play a key role in atherosclerotic plaque formation, rupture, and thrombotic ischemia. This study investigates genes implicated in OxLDL uptake (CD36, SRA, cholesterol efflux inhibition (adipophilin, ADFP, and inflammatory recruitments of leukocytes (IL-8 in plaque lesion areas (PLAs compared to nonplaque lesion areas NPLAs in human carotid endarterectomy specimens. Gene and protein expressions were assayed using quantitative PCR and quantitative immunohistochemistry. Pearson tests were used to investigate potential correlation between (a different gene expressions and (b gene expression and patient's plasma constituents. CD36, SRA, ADFP, and IL-8 were shown to be significantly more expressed in PLA compared to NPLA. In PLA, a significant correlation was observed between CD36, SRA, ADFP, and IL-8 mRNA levels. Moreover, CD36 expression level was significantly inversely correlated to plasma marker ApoAI. The above investigated genes/proteins may play a key role in the maturation of atherosclerotic lesions.

  14. Pulsatility Index of Blood Echogenicity of the Human Radial and Common Carotid Arteries: Relation with Age and Stroke

    Energy Technology Data Exchange (ETDEWEB)

    Bok, Tae Hoon; Kong, Qi; Nam, Kweon Ho; Choi, Jay Chol; Paeng, Dong Guk [Department of Ocean System Engineering, Jeju National University, Jeju (Korea, Republic of)

    2012-10-15

    In the present paper, the ultrasound blood images were measured at both the human radial artery(RA) and common carotid artery(CCA), depending on the age, and the pulsatility index of blood echogenicity(PIBE) was analyzed. In addition, the ultrasound blood images were measured at both RA and CCA of both the stroke patients and the control group, and PIBE was compared. PIBE of RA for the young group was similar with that for the old group (0.13{+-}0.21 and 0.16{+-}0.03). PIBE of CCA for the young group, however, was larger than that for the old group (0.70{+-}0.21 and 0.32{+-}0.01), and was more variable depending on the subject. Similarly, the fibrinogen concentrations of the patients (336{+-}61 and 340{+-}126 mg/dl) were more than that of the control group (264{+-}38 and 43 mg/dl), for both RA and CCA. The results indicate the possibility of the ultrasonic test on the correlation between erythrocyte aggregation and stroke, and it is expected that the in-vivo EA measurement would be clinically useful.

  15. Fast LC-MS/MS analysis of free oxysterols derived from reactive oxygen species in human plasma and carotid plaque.

    Science.gov (United States)

    Helmschrodt, Christin; Becker, Susen; Schröter, Jenny; Hecht, Max; Aust, Gabriela; Thiery, Joachim; Ceglarek, Uta

    2013-10-21

    A rapid liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the quantification of reactive oxygen species (ROS) derived free oxysterols and cholesterol in human plasma and atherosclerotic plaque. In vitro autoxidation of cholesterol during sample pretreatment was avoided by applying only one protein precipitation and re-concentration step using 80 μl plasma. For preparation of 10mg atherosclerotic plaques an additional liquid-liquid extraction was included. Free 7-keto-, 7-α/ß-hydroxy-, 5,6-α-epoxy-, 5,6-β-epoxycholesterol, cholestane-3ß,5α,6ß-triol and cholesterol were separated within 7 min on a monolithic column. An API 4000 tandem mass spectrometer was applied in positive ionization mode using atmospheric pressure chemical ionization. The detection limit was 0.1 ng/ml and the linearity ranged from 0.5 to 0.75 to 2000 ng/ml for the oxysterols and from 50 to 1000 μg/ml for cholesterol. Recovery was between 80.9 and 107.9%. Between-run imprecision ranged from 7.9 to 11.7%. Analysis of plasma samples from additional 50 middle-aged volunteers revealed a large inter-individual variability (e.g. 7-ketocholesterol 2.63-30.47 ng/ml). Oxysterol concentrations normalized to cholesterol were about 43 times higher in carotid plaque compared to plasma (n=5). This rapid LC-MS/MS method enables reliable quantification focused on especially ROS-derived oxysterols in human plasma and atherosclerotic plaque samples under high-throughput conditions. © 2013. Published by Elsevier B.V. All rights reserved.

  16. Cervical sympathetic chain schwannoma masquerading as a carotid body tumour with a postoperative complication of first-bite syndrome.

    LENUS (Irish Health Repository)

    Casserly, Paula

    2012-01-31

    Carotid body tumours (CBT) are the most common tumours at the carotid bifurcation. Widening of the bifurcation is usually demonstrated on conventional angiography. This sign may also be produced by a schwannoma of the cervical sympathetic plexus. A 45-year-old patient presented with a neck mass. Investigations included contrast-enhanced CT, MRI and magnetic resonance arteriography with contrast enhancement. Radiologically, the mass was considered to be a CBT due to vascular enhancement and splaying of the internal and external carotid arteries. Intraoperatively, it was determined to be a cervical sympathetic chain schwannoma (CSCS). The patient had a postoperative complication of first-bite syndrome (FBS).Although rare, CSCS should be considered in the differential diagnosis for tumours at the carotid bifurcation. Damage to the sympathetic innervation to the parotid gland can result in severe postoperative pain characterised by FBS and should be considered in all patients undergoing surgery involving the parapharyngeal space.

  17. Carotid and Aortic Stiffness in Patients with Heterozygous Familial Hypercholesterolemia.

    Directory of Open Access Journals (Sweden)

    Alexandra I Ershova

    Full Text Available The role of plasma cholesterol in impairing arterial function and elasticity remains unclear. We evaluated arterial stiffness, measured locally in the common carotid artery by high-resolution echo-tracking, and aortic stiffness, using carotid-femoral pulse wave velocity (PWV (the "gold-standard" measurement of arterial stiffness, in treatment-naive patients with heterozygous familial hypercholesterolemia (FH.The study included 66 patients with FH (10-66 years old and 57 first-degree relatives without FH (11-61 years old. Carotid-femoral PWV was determined by SphygmoCor (AtCor, Australia. The parameters of carotid stiffness β-index, Peterson elastic modulus and local PWV were assessed with regard to the common carotid artery at a distance of 1cm from the bifurcation (AlokaProsound Alpha7, Japan.FH patients showed significantly higher β-index (6.3(4.8-8.2 vs. 5.2(4.2-6.4, p = 0.005, Ep (78(53-111 kPa vs. 62(48-79 kPa, p = 0.006, local PWV (5.4(4.5-6.4 m/c vs. 4.7(4.2-5.4 m/c, p = 0.005, but comparable values of carotid-femoral PWV (6.76(7.0-7.92 m/c vs. 6.48(6.16-7.12 m/c, p = 0.138. Carotid arteries and the aorta stiffened with age in patients with FH, but after 30 years, carotid arteries stiffened more significantly than the aorta.Our study demonstrated that treatment-naive patients with FH had stiffer carotid arteries than their relatives, but showed no difference in aortic stiffness. We also found out that the rate of reduction of elasticity of the aorta and carotid arteries in FH patients varies: it is observed earlier in carotid arteries than in the aorta.

  18. Combining carotid intima-media thickness with carotid plaque on screening for coronary heart disease.

    Science.gov (United States)

    Wald, David S; Bestwick, Jonathan P; Morton, Geraint; Drummond, Linda; Jenkins, Nick; Khodabakhsh, Pouran; Curzen, Nick P

    2009-01-01

    Ultrasound-detected carotid artery intima-media thickness (IMT) and carotid plaque are possible screening tests for coronary heart disease (CHD) among asymptomatic individuals. To assess the increase in screening performance of combining carotid IMT and plaque compared with each measurement alone in the identification of individuals with CHD. Ultrasound examination of left and right carotid arteries was performed on 100 individuals (median age 57), 55 with a history of CHD (unstable angina or myocardial infarction) and 45 without. IMT measurements were taken from the common carotid artery and plaque was identified above, at and below the carotid bifurcation. Associations between IMT and plaque were determined using logistic regression, and screening performance was assessed from the distributions of IMT and plaque among cases and controls. At a false-positive rate of 5%, IMT (cut-off >0.75 mm) identified 30% (95% CI 14-58) of affected individuals. There was an increase in the detection rate of 8 percentage points (1-33%) using IMT and plaque combined compared with IMT alone. As the false-positive increased, the difference in the detection rate increased, up to a maximum of 20 percentage points (5-38%) at a false-positive rate of 20%. The comparison of IMT and plaque combined with plaque alone could only be estimated for the false-positive rate observed using plaque alone (18%); at this point the detection rate was 72% for plaque and 75% for plaque and IMT combined, an increase of 3 percentage points (0-4%). In screening for CHD, combining carotid IMT measurement with plaque assessment is better than using either measurement alone, but the improvement in discrimination is not sufficient to make carotid ultrasound screening for CHD worthwhile.

  19. Expansion of the Multi-Link Frontier™ Coronary Bifurcation Stent: Micro-Computed Tomographic Assessment in Human Autopsy and Porcine Heart Samples

    Science.gov (United States)

    Kralev, Stefan; Haag, Benjamin; Spannenberger, Jens; Lang, Siegfried; Brockmann, Marc A.; Bartling, Soenke; Marx, Alexander; Haase, Karl-Konstantin; Borggrefe, Martin; Süselbeck, Tim

    2011-01-01

    Background Treatment of coronary bifurcation lesions remains challenging, beyond the introduction of drug eluting stents. Dedicated stent systems are available to improve the technical approach to the treatment of these lesions. However dedicated stent systems have so far not reduced the incidence of stent restenosis. The aim of this study was to assess the expansion of the Multi-Link (ML) Frontier™ stent in human and porcine coronary arteries to provide the cardiologist with useful in-vitro information for stent implantation and selection. Methodology/Principal Findings Nine ML Frontier™ stents were implanted in seven human autopsy heart samples with known coronary artery disease and five ML Frontier™ stents were implanted in five porcine hearts. Proximal, distal and side branch diameters (PD, DD, SBD, respectively), corresponding opening areas (PA, DA, SBA) and the mean stent length (L) were assessed by micro-computed tomography (micro-CT). PD and PA were significantly smaller in human autopsy heart samples than in porcine heart samples (3.54±0.47 mm vs. 4.04±0.22 mm, p = 0.048; 10.00±2.42 mm2 vs. 12.84±1.38 mm2, p = 0.034, respectively) and than those given by the manufacturer (3.54±0.47 mm vs. 4.03 mm, p = 0.014). L was smaller in human autopsy heart samples than in porcine heart samples, although data did not reach significance (16.66±1.30 mm vs. 17.30±0.51 mm, p = 0.32), and significantly smaller than that given by the manufacturer (16.66±1.30 mm vs. 18 mm, p = 0.015). Conclusions/Significance Micro-CT is a feasible tool for exact surveying of dedicated stent systems and could make a contribution to the development of these devices. The proximal diameter and proximal area of the stent system were considerably smaller in human autopsy heart samples than in porcine heart samples and than those given by the manufacturer. Special consideration should be given to the stent deployment procedure (and to the follow-up) of dedicated

  20. Expansion of the Multi-Link Frontier™ coronary bifurcation stent: micro-computed tomographic assessment in human autopsy and porcine heart samples.

    Science.gov (United States)

    Kralev, Stefan; Haag, Benjamin; Spannenberger, Jens; Lang, Siegfried; Brockmann, Marc A; Bartling, Soenke; Marx, Alexander; Haase, Karl-Konstantin; Borggrefe, Martin; Süselbeck, Tim

    2011-01-01

    Treatment of coronary bifurcation lesions remains challenging, beyond the introduction of drug eluting stents. Dedicated stent systems are available to improve the technical approach to the treatment of these lesions. However dedicated stent systems have so far not reduced the incidence of stent restenosis. The aim of this study was to assess the expansion of the Multi-Link (ML) Frontier™ stent in human and porcine coronary arteries to provide the cardiologist with useful in-vitro information for stent implantation and selection. Nine ML Frontier™ stents were implanted in seven human autopsy heart samples with known coronary artery disease and five ML Frontier™ stents were implanted in five porcine hearts. Proximal, distal and side branch diameters (PD, DD, SBD, respectively), corresponding opening areas (PA, DA, SBA) and the mean stent length (L) were assessed by micro-computed tomography (micro-CT). PD and PA were significantly smaller in human autopsy heart samples than in porcine heart samples (3.54±0.47 mm vs. 4.04±0.22 mm, p = 0.048; 10.00±2.42 mm(2) vs. 12.84±1.38 mm(2), p = 0.034, respectively) and than those given by the manufacturer (3.54±0.47 mm vs. 4.03 mm, p = 0.014). L was smaller in human autopsy heart samples than in porcine heart samples, although data did not reach significance (16.66±1.30 mm vs. 17.30±0.51 mm, p = 0.32), and significantly smaller than that given by the manufacturer (16.66±1.30 mm vs. 18 mm, p = 0.015). Micro-CT is a feasible tool for exact surveying of dedicated stent systems and could make a contribution to the development of these devices. The proximal diameter and proximal area of the stent system were considerably smaller in human autopsy heart samples than in porcine heart samples and than those given by the manufacturer. Special consideration should be given to the stent deployment procedure (and to the follow-up) of dedicated stent systems, considering final intravascular ultrasound or

  1. Expansion of the Multi-Link Frontier™ coronary bifurcation stent: micro-computed tomographic assessment in human autopsy and porcine heart samples.

    Directory of Open Access Journals (Sweden)

    Stefan Kralev

    Full Text Available BACKGROUND: Treatment of coronary bifurcation lesions remains challenging, beyond the introduction of drug eluting stents. Dedicated stent systems are available to improve the technical approach to the treatment of these lesions. However dedicated stent systems have so far not reduced the incidence of stent restenosis. The aim of this study was to assess the expansion of the Multi-Link (ML Frontier™ stent in human and porcine coronary arteries to provide the cardiologist with useful in-vitro information for stent implantation and selection. METHODOLOGY/PRINCIPAL FINDINGS: Nine ML Frontier™ stents were implanted in seven human autopsy heart samples with known coronary artery disease and five ML Frontier™ stents were implanted in five porcine hearts. Proximal, distal and side branch diameters (PD, DD, SBD, respectively, corresponding opening areas (PA, DA, SBA and the mean stent length (L were assessed by micro-computed tomography (micro-CT. PD and PA were significantly smaller in human autopsy heart samples than in porcine heart samples (3.54±0.47 mm vs. 4.04±0.22 mm, p = 0.048; 10.00±2.42 mm(2 vs. 12.84±1.38 mm(2, p = 0.034, respectively and than those given by the manufacturer (3.54±0.47 mm vs. 4.03 mm, p = 0.014. L was smaller in human autopsy heart samples than in porcine heart samples, although data did not reach significance (16.66±1.30 mm vs. 17.30±0.51 mm, p = 0.32, and significantly smaller than that given by the manufacturer (16.66±1.30 mm vs. 18 mm, p = 0.015. CONCLUSIONS/SIGNIFICANCE: Micro-CT is a feasible tool for exact surveying of dedicated stent systems and could make a contribution to the development of these devices. The proximal diameter and proximal area of the stent system were considerably smaller in human autopsy heart samples than in porcine heart samples and than those given by the manufacturer. Special consideration should be given to the stent deployment procedure (and to the follow

  2. Bifurcation of Mobility, Bifurcation of Law : Externalization of migration policy before the EU Court of Justice

    NARCIS (Netherlands)

    Spijkerboer, T.P.

    2017-01-01

    The externalization of European migration policy has resulted in a bifurcation of global human mobility, which is divided along a North/South axis. In two judgments, the EU Court of Justice was confronted with cases challenging the exclusion of Syrian refugees from Europe. These cases concern core

  3. Asymmetric bifurcated halogen bonds.

    Science.gov (United States)

    Novák, Martin; Foroutan-Nejad, Cina; Marek, Radek

    2015-03-07

    Halogen bonding (XB) is being extensively explored for its potential use in advanced materials and drug design. Despite significant progress in describing this interaction by theoretical and experimental methods, the chemical nature remains somewhat elusive, and it seems to vary with the selected system. In this work we present a detailed DFT analysis of three-center asymmetric halogen bond (XB) formed between dihalogen molecules and variously 4-substituted 1,2-dimethoxybenzene. The energy decomposition, orbital, and electron density analyses suggest that the contribution of electrostatic stabilization is comparable with that of non-electrostatic factors. Both terms increase parallel with increasing negative charge of the electron donor molecule in our model systems. Depending on the orientation of the dihalogen molecules, this bifurcated interaction may be classified as 'σ-hole - lone pair' or 'σ-hole - π' halogen bonds. Arrangement of the XB investigated here deviates significantly from a recent IUPAC definition of XB and, in analogy to the hydrogen bonding, the term bifurcated halogen bond (BXB) seems to be appropriate for this type of interaction.

  4. Carotid Artery Disease

    Science.gov (United States)

    ... head with blood. If you have carotid artery disease, the arteries become narrow or blocked, usually because ... other substances found in the blood. Carotid artery disease is serious because it can block the blood ...

  5. Carotid artery surgery - slideshow

    Science.gov (United States)

    ... right- and left-internal carotid arteries, and the right- and left-external carotid arteries. The carotid arteries deliver oxygen-rich blood from the heart to both the head and brain. Review Date 6/1/2015 Updated by: Daniel ...

  6. Bifurcations sights, sounds, and mathematics

    CERN Document Server

    Matsumoto, Takashi; Kokubu, Hiroshi; Tokunaga, Ryuji

    1993-01-01

    Bifurcation originally meant "splitting into two parts. " Namely, a system under­ goes a bifurcation when there is a qualitative change in the behavior of the sys­ tem. Bifurcation in the context of dynamical systems, where the time evolution of systems are involved, has been the subject of research for many scientists and engineers for the past hundred years simply because bifurcations are interesting. A very good way of understanding bifurcations would be to see them first and study theories second. Another way would be to first comprehend the basic concepts and theories and then see what they look like. In any event, it is best to both observe experiments and understand the theories of bifurcations. This book attempts to provide a general audience with both avenues toward understanding bifurcations. Specifically, (1) A variety of concrete experimental results obtained from electronic circuits are given in Chapter 1. All the circuits are very simple, which is crucial in any experiment. The circuits, howev...

  7. Transport and Deposition of Micro-and Nano-Particles in Human Tracheobronchial Tree by an Asymmetric Multi-Level Bifurcation Model

    Directory of Open Access Journals (Sweden)

    Lin Tian

    2012-06-01

    Full Text Available Transport and deposition of particles in the upper tracheobronchial tree were analyzed using a multi-level asymmetric lung bifurcation model. The first three generations of tracheobronchial tree were included in the study. The laryngeal jet at the trachea entrance was modeled as an effective turbulence disturbance, and the study was focused on how to accurately simulate the airflow and predict the motion of the inhaled particles. Downstream in the lower level of the bronchial region, a laminar flow model was used, as smoother flow condition was expected. Transport and deposition of nano- and micro-scale spherical particles in the range of 0.01 μm to 30 μm were evaluated. The particle local deposition pattern and deposition rate in the lung bifurcation was discussed. The proposed multi-level asymmetric lung bifurcation model was found to be flexible, easy to use and computationally highly efficient. It was also shown that the selection of the anisotropic Reynolds stress transport turbulence model (RSTM was appropriate, and the use of the enhanced two-layer model boundary treatment was needed for accurate simulation of the turbulent airflow conditions in the upper airways.

  8. A CT study of the prevalence of carotid artery calcification in dental patients

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Suk Ja; Lee, Jae Seo; Yoon, Woong [Chonnam National Univ. Medical School, Gwangju (Korea, Republic of)

    2006-09-15

    Stroke is one of the leading causes of death in Korea. Atherosclerotic disease in the carotid artery bifurcation is the most common cause of stroke. The carotid artery calcification is easily appreciated by CT(Computed tomography). CT is often taken in a dental hospital for the diagnosis of inflammation. injury, cyst or tumor on maxillofacial region. However, there was no report of carotid artery calcification on CT in dental patients. The presence of carotid artery calcification was evaluated by an experienced radiologist on CT scans of 287 patients (166 males, 121 females, average age 42, range 6 to 86 years) and the medical history of the patient and the interpretation of CT were reviewed. Carotid artery calcification was detected on CT scans of 57 patients (19.8%; 35 males, 22 females). All the male patients with carotid artery calcification were older than 50, and all the female patients with carotid artery calcification were older than 60. Among the 57 patients, 10 had Diabetes mellitus, 20 had cardiovascular disease, 3 had history of stroke and 3 underwent radiation therapy for head and neck cancer. Carotid artery calcification was not included in the interpretation of CT of dental patients except one patient. The prevalence of carotid artery calcification on CT of dental patients was about 20% in this study. Carotid artery calcification should be included in the interpretation of CT of dental patients.

  9. Experimental Study of Flow in a Bifurcation

    Science.gov (United States)

    Fresconi, Frank; Prasad, Ajay

    2003-11-01

    An instability known as the Dean vortex occurs in curved pipes with a longitudinal pressure gradient. A similar effect is manifest in the flow in a converging or diverging bifurcation, such as those found in the human respiratory airways. The goal of this study is to characterize secondary flows in a bifurcation. Particle image velocimetry (PIV) and laser-induced fluorescence (LIF) experiments were performed in a clear, plastic model. Results show the strength and migration of secondary vortices. Primary velocity features are also presented along with dispersion patterns from dye visualization. Unsteadiness, associated with a hairpin vortex, was also found at higher Re. This work can be used to assess the dispersion of particles in the lung. Medical delivery systems and pollution effect studies would profit from such an understanding.

  10. Bifurcations in two-dimensional reversible maps

    NARCIS (Netherlands)

    Post, T.; Capel, H.W.; Quispel, G.R.W.; van der Weele, J.P.

    1990-01-01

    We give a treatment of the non-resonant bifurcations involving asymmetric fixed points with Jacobian J≠1 in reversible mappings of the plane. These bifurcations include the saddle-node bifurcation not in the neighbourhood of a fixed point with J≠1, as well as the so-called transcritical bifurcations

  11. Bifurcation Adds Flavor to Basketball

    CERN Document Server

    Min, Byeong June

    2016-01-01

    We report an emergence of bifurcation in basketball, a single-particle system governed by Newtonian mechanics. When shooting the basketball, the obvious control parameters are the launch speed and the launch angle. We propose to use the three-dimensional velocity phase-space volume associated with the given launch parameters to quantify the difficulty of the shooting. The optimal launch angle that maximizes the associated phase-space volume undergoes a bifurcation as the launch speed is increased, if the shooter is farther than a critical distance away from the hoop. Thus, the bifurcation makes it very important to control the launch speed accurately. If the air resistance is removed, the bifurcation disappears and the phase-space volume distribution becomes dispersionless and shrinks in magnitude.

  12. [Revascularization of the carotid and vertebral arteries in the elderly].

    Science.gov (United States)

    Illuminati, G; Bezzi, M; D'Urso, A; Giacobbi, D; Ceccanei, G; Vietri, F

    2004-01-01

    From January 1994 to July 2004, 323 patients underwent 348 revascularization of carotid bifurcation for atherosclerotic stenoses. Eighty eight patients (group A) were 75 year-old or older, whereas 235 (group B) were younger than 75 years. Postoperative mortality/neurologic morbidity rate was 1% in group A, and 1.4% in group B. At 5 years, patency and freedom from symptoms/stroke were, respectively, 91% and 92% in group A, and 89% and 91% in group B. None of these differences was statistically significant. In the same time period, 26 internal carotid arteries were revascularized in 24 patients, 75 or more aged, for a symptomatic kinking. Postoperative mortality/morbidity rate was absent, whereas, at 5 years, patency and freedom from symptoms/stroke were, respectively, 88% and 92%. Twelve vertebral arteries were revascularized in 12 patients, 75 or more aged, for invalidating symptoms of vertebrobasilar insufficiency. Postoperative mortality/neurologic morbidity rate was absent. In one case postoperative recurrence of symptoms occurred, despite a patent revascularization. Patency and freedom from symptoms/stroke were 84% and 75%, at 5 years. Revascularization of carotid and vertebral arteries in the elderly can be accomplished with good results, superposable to those of standard revascularization of carotid bifurcation in a younger patients' population.

  13. Protective effect of posterior cerebral circulation on carotid body ischemia.

    Science.gov (United States)

    Aydin, M D; Ozkan, U; Gündoğdu, C; Onder, A

    2002-04-01

    Carotid Bodies (CB) are fed mainly by External Carotid Artery (ECA) and rarely by Internal Carotid Artery (ICA). We aimed to investigate the effect of Bilateral Common Carotid Artery ligation and BCCAL plus bilateral external carotid artery ligation on CB. This study has been conducted on 30 hybrid male rabbits. Normal CB analyses were made in six of these animals and others divided into two groups. BCCAL has been applied to the 1st group, and the 2nd group has undergone bilateral ECA ligation in addition to BCCAL. After sacrificing the animals, both sides CB were histopathologically observed. Normal and ischemic cells were counted. Bilateral Common Carotid Artery ligation did not cause total atrophy in CB. Partial reversible atrophy of CB was seen in group I, but that atrophy was found to be irreversible and all animals died within one week after ligation in group II. Retrograde blood flow mechanisms and collateral circulation impede the oligemic CB atrophy after BCCAL. But bilateral ECA ligation, in addition to BCCAL, causes both sides irreversible CB atrophy and death of animals within one week of ligation. The CB are parasympathetic paraganglia. They are chemoreceptors and located at the bifurcation zone of common carotid arteries. They are fed mainly by ECA or by its branches and rarely by ICA. As a consequence of this, BCCAL and/or ligation of external branches of common carotid artery may lead to an ischemic impairment of CB. In order to analyse the effect of carotid stenosis on CB, CB were directly examined in 6 of 30 hybrid rabbits. BCCAL was applied to twelve rabbits (group I) with ligation of both ECA in addition to BCCAL were made to the others (group II). Animals were followed up four months in group I; but all of the animals in group II died within one week. From both sides the CB were taken including the carotid bifurcation and histopathological changes were evaluated. As a result, it has been observed that incomplete ischemic lesions have developed

  14. Inraoperative and Histological Visualization of Disrupted Vulnerable Plaques following Diagnostic Angiography of Moderate Carotid Stenosis

    Directory of Open Access Journals (Sweden)

    Tatsushi Mutoh

    2010-01-01

    Full Text Available Background. Digital subtraction angiography (DSA remains an important tool for diagnosis of carotid stenosis but is associated with risk for periprocedural complications. This is the first report of direct intraoperative and histolopathologic visualization of DSA-related carotid plaque disruption. Case. A 64-year-old man diagnosed to have a 60% right carotid stenosis received diagnostic DSA for therapeutic decision-making. He developed transient left hand numbness and weakness immediately after the procedure. Intraoperative imaging during carotid endarterectomy revealed a fragile plaque with sharp surface laceration and intraplaque hemorrhage at the bifurcation. Microscopy of the specimen demonstrated a large atheromatous plaque with fibrous hypertrophy and intraplaque hemorrhage filled with recent hemorrhagic debris. Conclusion. The visualized carotid lesion was more serious than expected, warning the danger of embolization or occlusion associated with the catheter maneuvers. Thus the highest level of practitioner training and technical expertise that ensures precise assessment of plaque characteristics should be encouraged.

  15. Quantitative angiography methods for bifurcation lesions: a consensus statement update from the European Bifurcation Club

    NARCIS (Netherlands)

    Collet, Carlos; Onuma, Yoshinobu; Cavalcante, Rafael; Grundeken, Maik; Généreux, Philippe; Popma, Jeffrey; Costa, Ricardo; Stankovic, Goran; Tu, Shengxian; Reiber, Johan H. C.; Aben, Jean-Paul; Lassen, Jens Flensted; Louvard, Yves; Lansky, Alexandra; Serruys, Patrick W.

    2017-01-01

    Bifurcation lesions represent one of the most challenging lesion subsets in interventional cardiology. The European Bifurcation Club (EBC) is an academic consortium whose goal has been to assess and recommend the appropriate strategies to manage bifurcation lesions. The quantitative coronary

  16. Human carotid plaque phosphatidylcholine specifically interacts with paraoxonase 1, increases its activity, and enhances its uptake by macrophage at the expense of its binding to HDL.

    Science.gov (United States)

    Cohen, Elad; Aviram, Michael; Khatib, Soliman; Artoul, Fadi; Rabin, Asaf; Mannheim, Dalit; Karmeli, Ron; Salamon, Tal; Vaya, Jacob

    2014-11-01

    Human carotid atherosclerotic plaque is in direct contact with circulatory blood components. Thus, plaque and blood components may affect each other. The current study presents the effects of plaque chloroform:methanol (C:M) extract on the HDL-associated enzyme paraoxnase 1 (PON1). This study is part of our investigation on the mutual effects of the interactions between atherosclerotic lesions and blood components. Recombinant PON1 (rePON1) was incubated with the human carotid plaques C:M extract and PON1 activities were analyzed. Lactonase and paraoxonase activities were elevated due to C:M treatment, by 140 and by 69%, respectively. Analytical chemistry analyses revealed specific phosphatidylcholines (PCs) as the plaque active components. Tryptophan fluorescence quenching assay, together with molecular docking, shows that PON1 activity is enhanced in correlation with the level of PC affinity to PON1. Molecular docking revealed that PCs interact specifically with H2-PON1 α-helix, which together with H1 enzyme α-helix links the protein to the HDL surface. These findings are supported by additional results from the PON1 ∆20 mutant that lack its H1-α-helix. Incubation of this mutant with the plaque C:M extract increased PON1 activity by only 20%, much less than the wild-type PON1 that elevated PON1 activity at the same concentration by as much as 95%. Furthermore, as much as the affinity of the enzyme to the PC was augmented, the ability of PON1 to bind to the HDL particle decreased. Finally, PON1 interaction with PC enhance its uptake into the macrophage cytoplasm. In conclusions, Specific lesion phosphatidylcholines (PCs) present in the human carotid plaque significantly enhance PON1 catalytic activities due to their interaction with the enzyme. Such a lesion׳s PC-PON1 interaction, in turn, competes with HDL PCs and enhances PON1 uptake by macrophage at the expense of PON1 binding to the HDL. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Influence of Cannulation Site on Carotid Perfusion During Extracorporeal Membrane Oxygenation in a Compliant Human Aortic Model.

    Science.gov (United States)

    Geier, Andreas; Kunert, Andreas; Albrecht, Günter; Liebold, Andreas; Hoenicka, Markus

    2017-10-01

    Blood oxygenized by veno-arterial extracorporeal membrane oxygenation (ECMO) can be returned to the aorta (central cannulation) or to peripheral arteries (axillar, femoral). Hemodynamic effects of these cannulation types were analyzed in a mock loop with an aortic model representative of normal anatomy and compliance under physiological pressures and flow rates. Pressures, flow rates, and contribution of ECMO flow to total flow as a measure of oxygen supply were monitored in the carotids. Steady or pulsatile ECMO flow, residual or no cardiac output, and intraaortic balloon pump counterpulsation were tested as independent factors. With residual heart function, central cannulation provided the best oxygenated flow and pressure to the carotid arteries (CA). Axillar cannulation preferentially perfused the right CA at the expense of the left CA. Femoral cannulation provided only lower amounts of oxygenated blood to both CA. Pulsation increased the surplus hemodynamic energy. Counterpulsation reduced flow with femoral cannulation but improved flow and pressure with axillar cannulation. Femoral cannulation failed to provide oxygenated blood to coronary and supraaortic arteries with residual heart function. Central cannulation provided the best hemodynamics and oxygen supply to the brain. With a resting heart but not with an ejecting heart, pulsatile ECMO flow enhanced CA hemodynamics.

  18. Percutaneous reconstruction of the innominate bifurcation using the retrograde 'kissing stents' technique

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, Shun-ichi; Kazekawa, Kiyoshi; Matsubara, Shuko [Fukuoka University Chikushi Hospital, Department of Neurosurgery, Chikushino, Fukuoka (Japan); Sugata, Sei [Bironoki Neurosurgical Hospital, Shibushi, Kagoshima (Japan)

    2006-08-15

    Obstructions of the supraaortic vessels are an important cause of morbidity associated with a variety of symptoms. Percutaneous transluminal angioplasty has evolved as an effective and safe treatment modality for occlusive lesions of the supraaortic vessels. However, the endovascular management of an innominate bifurcation has not previously been reported. A 53-year-old female with a history of systematic hypertension, diabetes mellitus and hypercholesterolemia presented with left hemiparesis and dysarthria. Angiography of the innominate artery showed a stenosis of the innominate bifurcation. The lesion was successfully treated using the retrograde kissing stent technique via a brachial approach and an exposed direct carotid approach. The retrograde kissing stent technique for the treatment of a stenosis of the innominate bifurcation was found to be a safe and effective alternative to conventional surgery. (orig.)

  19. Carotid Stump Syndrome

    Directory of Open Access Journals (Sweden)

    Lara Toufic Dakhoul MD

    2014-08-01

    Full Text Available Objectives. To highlight the case of a patient with multiple transient ischemic attacks and visual disturbances diagnosed with carotid stump syndrome and managed with endovascular approach. Case Presentation. We present the case of a carotid stump syndrome in an elderly patient found to have moderate left internal carotid artery stenosis in response to an advertisement for carotid screening. After a medical therapeutic approach and a close follow-up, transient ischemic attacks recurred. Computed tomographic angiography showed an occlusion of the left internal carotid artery and the presence of moderate stenosis in the right internal carotid artery, which was treated by endovascular stenting and balloon insertion. One month later, the patient presented with visual disturbances due to the left carotid stump and severe stenosis of the left external carotid artery that was reapproached by endovascular stenting. Conclusion. Considerations should be given to the carotid stump syndrome as a source of emboli for ischemic strokes, and vascular assessment could be used to detect and treat this syndrome.

  20. Carotid artery stenting; Karotisangioplastie

    Energy Technology Data Exchange (ETDEWEB)

    Fiehler, Jens [Universitaetsklinikum Eppendorf, Hamburg (Germany). Klinik und Poliklinik fuer Neuroradiologische Diagnostik und Intervention, Diagnostikzentrum

    2009-09-15

    An ipsilateral stenosis of the internal carotid artery is found in 10 - 15 % of all ischemic strokes and indicates an increased risk of a second stroke. Carotid artery stenting (CAS) is a therapy that is established for many years. CAS reveals complication rates and long-term efficacy comparable to carotid endarterectomy (TEA). Especially younger patients seem to benefit from CAS. Abilities and experiences of the therapist and the choice of the techniques used are critical for patient safety. The efficacy of CAS for treatment of asymptomatic carotid stenosis is probable but still unproven in prospective-randomized trial. (orig.)

  1. Increased Levels of Human Carotid Lesion Linoleic Acid Hydroperoxide in Symptomatic and Asymptomatic Patients Is Inversely Correlated with Serum HDL and Paraoxonase 1 Activity

    Directory of Open Access Journals (Sweden)

    Elad Cohen

    2012-01-01

    Full Text Available Human carotid plaque components interact directly with circulating blood elements and thus they might affect each other. We determined plaque paraoxonase1 (PON1 hydrolytic-catalytic activity and compared plaque and blood levels of lipids, HDL, PON1, and HbA1c, as well as plaque-oxidized lipids in symptomatic and asymptomatic patients. Human carotid plaques were obtained from symptomatic and asymptomatic patients undergoing routine endarterectomy, and the lesions were ground and extracted for PON activity and lipid content determinations. Plaque PONs preserved paraoxonase, arylesterase, and lactonase activities. The PON1-specific inhibitor 2-hydroxyquinoline almost completely inhibited paraoxonase and lactonase activities, while only moderately inhibiting arylesterase activity. Oxysterol and triglyceride levels in plaques from symptomatic and asymptomatic patients did not differ significantly, but plaques from symptomatic patients had significantly higher (135% linoleic acid hydroperoxide (LA-13OOH levels. Their serum PON1 activity, cholesterol and triglyceride levels did not differ significantly, but symptomatic patients had significantly lower (28% serum HDL levels and higher (18% HbA1c levels. Thus LA-13OOH, a major atherogenic plaque element, showed significant negative correlations with serum PON1 activity and HDL levels, and a positive correlation with the prodiabetic atherogenic HbA1c. Plaque PON1 retains its activity and may decrease plaque atherogenicity by reducing specific oxidized lipids (e.g., LA-13OOH. The inverse correlation between plaque LA-13OOH level and serum HDL level and PON1 activity suggests a role for serum HDL and PON1 in LA-13OOH accumulation.

  2. Quantitative angiography methods for bifurcation lesions

    DEFF Research Database (Denmark)

    Collet, Carlos; Onuma, Yoshinobu; Cavalcante, Rafael

    2017-01-01

    Bifurcation lesions represent one of the most challenging lesion subsets in interventional cardiology. The European Bifurcation Club (EBC) is an academic consortium whose goal has been to assess and recommend the appropriate strategies to manage bifurcation lesions. The quantitative coronary...... angiography (QCA) methods for the evaluation of bifurcation lesions have been subject to extensive research. Single-vessel QCA has been shown to be inaccurate for the assessment of bifurcation lesion dimensions. For this reason, dedicated bifurcation software has been developed and validated. These software...

  3. HIV Infection and Carotid Artery Intima-media Thickness: Pooled Analyses Across 5 Cohorts of the NHLBI HIV-CVD Collaborative.

    Science.gov (United States)

    Hanna, David B; Guo, Mengye; Bůžková, Petra; Miller, Tracie L; Post, Wendy S; Stein, James H; Currier, Judith S; Kronmal, Richard A; Freiberg, Matthew S; Bennett, Siiri N; Shikuma, Cecilia M; Anastos, Kathryn; Li, Yanjie; Tracy, Russell P; Hodis, Howard N; Delaney, Joseph A; Kaplan, Robert C

    2016-07-15

    Age and human immunodeficiency virus (HIV) treatment may affect the association of HIV infection with atherosclerosis. We used identical carotid artery B-mode ultrasonographic methods in 5 cohorts participating in the National Heart, Lung, and Blood Institute HIV-CVD Collaborative to measure intima-media thickness of the right far wall of the common carotid artery (CCA-IMT) and carotid artery bifurcation (BIF-IMT) between 2010 and 2013. Participants aged 6-75 years were either HIV infected or uninfected. Linear regression assessed associations of CCA-IMT and BIF-IMT with HIV infection and cardiovascular disease risk factors, within age and HIV treatment groups. Adjustment variables included sex, race/ethnicity, smoking, height, weight, and use of antihypertensive and lipid-lowering drugs. We studied 867 HIV-infected and 338 HIV-uninfected male and 696 HIV-infected and 246 HIV-uninfected female participants. Among both middle-aged (30-49 years) and older adults (50-75 years), HIV-infected participants had CCA-IMT and BIF-IMT values that were similar to or lower than those in HIV-uninfected participants. In contrast, among those aged 6-29 years, HIV infection was associated with higher CCA-IMT and BIF-IMT values. Among HIV-infected participants, associations of higher systolic blood pressure and lower high-density lipoprotein cholesterol with Carotid artery intima-media thickness strengthened with age. The effects of HIV on carotid artery structure may differ across the lifespan, with traditional determinants of cardiovascular disease burden playing a larger role and HIV playing a lesser role in older adults than in young adults and children. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  4. Optimal MR Plaque Imaging for Cervical Carotid Artery Stenosis in Predicting the Development of Microembolic Signals during Exposure of Carotid Arteries in Endarterectomy: Comparison of 4 T1-Weighted Imaging Techniques.

    Science.gov (United States)

    Sato, Y; Ogasawara, K; Narumi, S; Sasaki, M; Saito, A; Tsushima, E; Namba, T; Kobayashi, M; Yoshida, K; Terayama, Y; Ogawa, A

    2016-06-01

    Preoperative identification of plaque vulnerability may allow improved risk stratification for patients considered for carotid endarterectomy. The present study aimed to determine which plaque imaging technique, cardiac-gated black-blood fast spin-echo, magnetization-prepared rapid acquisition of gradient echo, source image of 3D time-of-flight MR angiography, or noncardiac-gated spin-echo, most accurately predicts development of microembolic signals during exposure of carotid arteries in carotid endarterectomy. Eighty patients with ICA stenosis (≥70%) underwent the 4 sequences of preoperative MR plaque imaging of the affected carotid bifurcation and then carotid endarterectomy under transcranial Doppler monitoring of microembolic signals in the ipsilateral middle cerebral artery. The contrast ratio of the carotid plaque was calculated by dividing plaque signal intensity by sternocleidomastoid muscle signal intensity. Microembolic signals during exposure of carotid arteries were detected in 23 patients (29%), 3 of whom developed new neurologic deficits postoperatively. Those deficits remained at 24 hours after surgery in only 1 patient. The area under the receiver operating characteristic curve to discriminate between the presence and absence of microembolic signals during exposure of the carotid arteries was significantly greater with nongated spin-echo than with black-blood fast spin-echo (difference between areas, 0.258; P carotid arteries in carotid endarterectomy more accurately than other MR plaque imaging techniques. © 2016 by American Journal of Neuroradiology.

  5. Carotid stenting and endarterectomy.

    Science.gov (United States)

    Yip, Hon-Kan; Sung, Pei-Hsun; Wu, Chiung-Jen; Yu, Cheuk-Man

    2016-07-01

    Stroke, either ischemic or hemorrhagic, remains the second commonest cause of death worldwide in the last decade. Etiologies for ischemic stroke (IS) vary widely. Atherothrombotic occlusion is an essential cause to which carotid artery stenosis (CAS) is a major contributor. Administration of anti-platelet agent to patients with CAS has been shown to reduce incidence of long-term IS. In additional, in patients with symptomatic CAS, clinical trials have demonstrated that carotid endarterectomy (CEA) is superior to medical therapy for prevention of future CAS-related IS. However, CEA is not suitable for CAS post-radiotherapy or those located at higher level of the internal carotid artery; and major complications of this procedure including cranial nerve injuries have stimulated the interest of using percutaneous transfemoral carotid stenting as an alternative approach. Although transfemoral arterial approach of carotid stenting is not inferior to CEA in improving clinical outcomes, it has been reported to be associated with vascular complication and has its limitations in patients with athero-occlusive disease of abdominal aorta or bilateral iliac arteries, level II or III aortic arch, or bovine type carotid arterial anatomy. Therefore, transradial/transbrachial arterial approach has emerged as a novel method for carotid stenting. This article provides a critical review on interventional approaches for the treatment of CAS. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. The influence of obesity on the assessment of carotid intima-media thickness.

    Science.gov (United States)

    Gállego Pérez-Larraya, Jaime; Irimia, Pablo; Martínez-Vila, Eduardo; Barba, Joaquín; Guembe, María Jesús; Varo, Nerea; Castellano, José María; Viñes, José Javier; Díez, Javier

    2012-10-01

    The assessment of carotid intima-media thickness (CIMT) may improve cardiovascular risk prediction. The optimal protocol for CIMT measurement is unclear. CIMT may be measured in the common carotid artery (CCA), carotid bifurcation (CB), and internal carotid artery (ICA), but measurements from CB and ICA are more difficult to obtain. We studied the influence of body mass index (BMI) and atheroma plaques on the capacity to obtain CIMT measurements at different carotid sites. Using an automatic system, CIMT was measured in 700 subjects aged 45-75, in the near and far walls of CCA, CB, and ICA bilaterally. The presence of atheroma plaques, BMI and vascular risk factors were recorded. CIMT measurements in CCA were possible in all except one subject. It was not possible to obtain CIMT measurements at CB or ICA in 24.1% of normal weight and 58.8% of obese subjects. The likelihood of obtaining CIMT measurement at all carotid sites decreased as the BMI increased. Atheroma plaques in a carotid segment did not preclude CIMT measurement at this site. CIMT measurements in distal carotid segments are more challenging in obese subjects. Measuring CIMT at CCA remains feasible in obese subjects and should be the primary endpoint in these subjects. Nevertheless, CB and ICA measurements, when feasible, would improve risk classification. Copyright © 2012 Wiley Periodicals, Inc.

  7. Current Approaches for Carotid Endarterectomy

    Directory of Open Access Journals (Sweden)

    Cengiz Köksal

    2010-12-01

    Full Text Available Permanent neurologic injuries and death following stroke, necessitates more vigorous treatment of carotid disease. Carotid stenting and carotid endarterectomy are treatment options in many centers besides medical treatment. Whether the patient is symptomatic or asymtomatic, indications and management strategies for treatment remain controversial. Despite the debate, carotid endarterectomy is still accepted to be the most efficientintervention to decrease risk of stroke due to carotid artery stenosis.

  8. Bifurcations analysis of turbulent energy cascade

    Energy Technology Data Exchange (ETDEWEB)

    Divitiis, Nicola de, E-mail: n.dedivitiis@gmail.com

    2015-03-15

    This note studies the mechanism of turbulent energy cascade through an opportune bifurcations analysis of the Navier–Stokes equations, and furnishes explanations on the more significant characteristics of the turbulence. A statistical bifurcations property of the Navier–Stokes equations in fully developed turbulence is proposed, and a spatial representation of the bifurcations is presented, which is based on a proper definition of the fixed points of the velocity field. The analysis first shows that the local deformation can be much more rapid than the fluid state variables, then explains the mechanism of energy cascade through the aforementioned property of the bifurcations, and gives reasonable argumentation of the fact that the bifurcations cascade can be expressed in terms of length scales. Furthermore, the study analyzes the characteristic length scales at the transition through global properties of the bifurcations, and estimates the order of magnitude of the critical Taylor-scale Reynolds number and the number of bifurcations at the onset of turbulence.

  9. A systematic literature review of the effect of carotid atherosclerosis on local vessel stiffness and elasticity.

    Science.gov (United States)

    Boesen, Mari E; Singh, Dilip; Menon, Bijoy K; Frayne, Richard

    2015-11-01

    This systematic literature review sought to determine the effects of carotid atherosclerotic plaque on local arterial stiffness. MedLine, EMBASE, and grey literature were searched with the following term: ("atherosclerosis" or "carotid atherosclerosis" or "carotid artery disease" or "carotid plaque") AND ("distensibility" or "elasticity" or "stiffness" or "compliance") NOT ("pulse wave velocity" or "PWV" or "carotid-ankle" or "ankle-brachial" or "augmentation index" or "cardio-ankle" or "CAVI" or "flow mediated dilation" or "FMD"). Results were restricted to English language articles reporting local arterial stiffness in human subjects with carotid atherosclerosis. Of the 1466 search results, 1085 abstracts were screened and 191 full-text articles were reviewed for relevance. The results of the 50 studies that assessed some measure of carotid arterial elasticity or stiffness in patients with carotid plaque were synthesized and reviewed. A number of different measures of carotid elasticity were found in the literature. Regardless of which metric was used, the majority of studies found increased carotid stiffness (or decreased distensibility) to be associated with carotid plaque presence, the degree of atherosclerosis, and incident stroke. Carotid artery mechanics are influenced by the presence of atherosclerotic plaque. The clinical applicability of carotid elasticity measures may be limited by the lack of reference values and standardized techniques. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  10. Common carotid artery occlusion presenting with recurrent syncopal episodes

    Directory of Open Access Journals (Sweden)

    Imran Kader

    2017-01-01

    Full Text Available Symptomatic common carotid artery (CCA occlusion is an uncommon occurrence that may require surgical intervention. We aim to describe a case of CCA occlusion that presented with the unusual symptom of recurrent syncope. A 69-year-old lady presented with a history of recurrent syncopal episodes and amaurosis fugax associated with left leg weakness. She was found to have a right CCA occlusion on duplex ultrasound and angiography. She underwent a right common carotid endarterectomy and intraoperative findings revealed a heavily calcified plaque in the CCA just proximal to the bifurcation with organised thrombus filling the CCA proximally. CCA occlusion can rarely present with recurrent syncopal episodes. Surgery may be curative.

  11. Carotid stenting versus carotid endarterectomy : Evidence basis and cost implications

    NARCIS (Netherlands)

    Janssen, M. P.; de Borst, G. J.; Mali, W. P. Th. M.; Kappelle, L. J.; Moll, F. L.; Ackerstaff, R. G. A.; Rothwell, P. M.; Brown, M. M.; van Sambeek, M. R.; Buskens, E.

    Objective: Carotid Angioplasty combined with Stenting (CAS) is increasingly performed because of its presumed benefits. A study was performed to identify key factors that determine the cost-effectiveness as compared to conventional carotid endarterectomy (CEA). Methods: The incremental

  12. Eversion carotid endarterectomy generates fewer microemboli than standard carotid endarterectomy

    DEFF Research Database (Denmark)

    Nielsen, Mingyuan; Sillesen, H H; Lorentzen, Jørgen E

    2000-01-01

    to test whether the occurrence of microembolism differed between eversion and standard carotid endarterectomy (CEA).......to test whether the occurrence of microembolism differed between eversion and standard carotid endarterectomy (CEA)....

  13. Carotid Artery Stenting Successfully Prevents Progressive Stroke Due to Mobile Plaque

    Directory of Open Access Journals (Sweden)

    Masahiro Oomura

    2015-05-01

    Full Text Available We report a case of progressive ischemic stroke due to a mobile plaque, in which carotid artery stenting successfully prevented further infarctions. A 78-year-old man developed acute multiple infarcts in the right hemisphere, and a duplex ultrasound showed a mobile plaque involving the bifurcation of the left common carotid artery. Maximal medical therapy failed to prevent further infarcts, and the number of infarcts increased with his neurological deterioration. Our present case suggests that the deployment of a closed-cell stent is effective to prevent the progression of the ischemic stroke due to the mobile plaque.

  14. Screening for Carotid Artery Stenosis

    Science.gov (United States)

    Understanding Task Force Recommendations Screening for Carotid Artery Stenosis The U.S. Preventive Services Task Force (Task Force) ... final recommendation statement on Screening for Carotid Artery Stenosis. This final recommendation statement applies to adults who ...

  15. Unilateral Carotid Body Resection in Resistant Hypertension

    Directory of Open Access Journals (Sweden)

    Krzysztof Narkiewicz, MD

    2016-08-01

    Full Text Available Animal and human data indicate pathological afferent signaling emanating from the carotid body that drives sympathetically mediated elevations in blood pressure in conditions of hypertension. This first-in-man, proof-of-principle study tested the safety and feasibility of unilateral carotid body resection in 15 patients with drug-resistant hypertension. The procedure proved to be safe and feasible. Overall, no change in blood pressure was found. However, 8 patients showed significant reductions in ambulatory blood pressure coinciding with decreases in sympathetic activity. The carotid body may be a novel target for treating an identifiable subpopulation of humans with hypertension.

  16. Bifurcations in the regularized Ericksen bar model

    OpenAIRE

    Grinfeld, M.; Lord, G. J. (Gabriel J.)

    2007-01-01

    We consider the regularized Ericksen model of an elastic bar on an elastic foundation on an interval with Dirichlet boundary conditions as a two-parameter bifurcation problem. We explore, using local bifurcation analysis and continuation methods, the structure of bifurcations from double zero eigenvalues. Our results provide evidence in support of M\\"uller's conjecture \\cite{Muller} concerning the symmetry of local minimizers of the associated energy functional and describe in detail the stru...

  17. Calcification of the intracranial carotid artery and its relation to the clinical and angiographic picture: an angiographic classification of asteriosclerosis cerebri

    Directory of Open Access Journals (Sweden)

    Valter Seixas

    1968-03-01

    Full Text Available Fifty six patients with arteriosclerosis cerebri confirmed by X-rays examinations were clinically and angiographically studied. Calcifications of the carotid artery were found predominantly in human beings between the ages of 55 and 65 and more often among men than among women, the proportion being 2.5 to 1. Nearly all arteriosclerotic patients with calcium deposits in the carotid artery showed several neurological and mental deficits, the most frequent initial symptoms being motor disturbances. Angiographic anormalities found in these patients can be classed into 3 groups: (a grade I— wavy course of the cerebral vessels, small number of peripheral brain vessels, formation of small knots, prolonged circulation time, arteria cerebri anterior with angular form, straight course and broad caliber; (b grade II— partial block, irregularities of wall and caliber, aneurysmal formations; (c grade III— total block of some vessels of the carotid system preventing a generalized or localized cerebral blood supply. Grades II and III angiographic abnormalities were most often seen at the syphon and at the carotid bifurcation in the neck (site of predilection. Most patients with a progressive clinical course belonged to the I group. The course of the disease did not differ in patients with grades II and III angiographic changes since usually the illness had an apoplectiform onset. Arteriosclerotic degenerative irregularities within the layers of the arteries (up to atheromatous patches may occur without reducing the arterial lumen. In such cases the patients may remain asymptomatic until there is a decompensation in the brain circulation due to many causes.

  18. Antiplatelet Therapy in Carotid Artery Stenting and Carotid Endarterectomy in the Asymptomatic Carotid Surgery Trial-2

    NARCIS (Netherlands)

    Huibers, A; Halliday, A; Bulbulia, R; Coppi, G; de Borst, G J|info:eu-repo/dai/nl/237108151

    OBJECTIVE: Strokes are infrequent but potentially serious complications following carotid intervention, but antiplatelet therapy can reduce these risks. There are currently no specific guidelines on dose or duration of peri-procedural antiplatelet treatment for patients undergoing carotid

  19. Staged bilateral carotid endarterectomy

    DEFF Research Database (Denmark)

    Schroeder, T; Sillesen, H; Engell, Hans Christian

    1986-01-01

    In a series of 56 staged bilateral carotid endarterectomies, new neurologic symptoms developed in 5% and 20% following the first and second procedure, respectively. All complications were transient or minor. The incidence of postendarterectomy hypertension was significantly higher following...... the second procedure, when operations were staged less than 3 weeks apart. A correlation between these hypertensive episodes and the occurrence of new neurologic symptoms could not be shown. However, as this correlation has been proved in several other reports, bilateral carotid endarterectomy is advised...

  20. Bifurcations in dissipative fermionic dynamics

    Science.gov (United States)

    Napolitani, Paolo; Colonna, Maria; Di Prima, Mariangela

    2014-05-01

    The Boltzmann-Langevin One-Body model (BLOB), is a novel one-body transport approach, based on the solution of the Boltzmann-Langevin equation in three dimensions; it is used to handle large-amplitude phase-space fluctuations and has a broad applicability for dissipative fermionic dynamics. We study the occurrence of bifurcations in the dynamical trajectories describing heavy-ion collisions at Fermi energies. The model, applied to dilute systems formed in such collisions, reveals to be closer to the observation than previous attempts to include a Langevin term in Boltzmann theories. The onset of bifurcations and bimodal behaviour in dynamical trajectories, determines the fragment-formation mechanism. In particular, in the proximity of a threshold, fluctuations between two energetically favourable mechanisms stand out, so that when evolving from the same entrance channel, a variety of exit channels is accessible. This description gives quantitative indications about two threshold situations which characterise heavy-ion collisions at Fermi energies. First, the fusion-to-multifragmentation threshold in central collisions, where the system either reverts to a compact shape, or splits into several pieces of similar sizes. Second, the transition from binary mechanisms to neck fragmentation (in general, ternary channels), in peripheral collisions.

  1. Non-clinical and Pre-clinical Testing to Demonstrate Safety of the Barostim Neo Electrode for Activation of Carotid Baroreceptors in Chronic Human Implants.

    Science.gov (United States)

    Wilks, Seth J; Hara, Seth A; Ross, Erika K; Nicolai, Evan N; Pignato, Paul A; Cates, Adam W; Ludwig, Kip A

    2017-01-01

    The Barostim neo™ electrode was developed by CVRx, Inc.to deliver baroreflex activation therapy (BAT)™ to treat hypertension and heart failure. The neo electrode concept was designed to deliver electrical stimulation to the baroreceptors within the carotid sinus bulb, while minimizing invasiveness of the implant procedure. This device is currently CE marked in Europe, and in a Pivotal (akin to Phase III) Trial in the United States. Here we present the in vitro and in vivo safety testing that was completed in order to obtain necessary regulatory approval prior to conducting human studies in Europe, as well as an FDA Investigational Device Exemption (IDE) to conduct a Pivotal Trial in the United States. Stimulated electrodes (10 mA, 500 μs, 100 Hz) were compared to unstimulated electrodes using optical microscopy and several electrochemical techniques over the course of 27 weeks. Electrode dissolution was evaluated by analyzing trace metal content of solutions in which electrodes were stimulated. Lastly, safety testing under Good Laboratory Practice guidelines was conducted in an ovine animal model over a 12 and 24 week time period, with results processed and evaluated by an independent histopathologist. Long-term stimulation testing indicated that the neo electrode with a sputtered iridium oxide coating can be stimulated at maximal levels for the lifetime of the implant without clinically significant dissolution of platinum or iridium, and without increasing the potential at the electrode interface to cause hydrolysis or significant tissue damage. Histological examination of tissue that was adjacent to the neo electrodes indicated no clinically significant signs of increased inflammation and no arterial stenosis as a result of 6 months of continuous stimulation. The work presented here involved rigorous characterization and evaluation testing of the neo electrode, which was used to support its safety for chronic implantation. The testing strategies discussed

  2. Objective Validation of Perfusion-Based Human Cadaveric Simulation Training Model for Management of Internal Carotid Artery Injury in Endoscopic Endonasal Sinus and Skull Base Surgery.

    Science.gov (United States)

    Shen, Jasper; Hur, Kevin; Zhang, Zhipeng; Minneti, Michael; Pham, Martin; Wrobel, Bozena; Zada, Gabriel

    2017-12-29

    The emergence of minimally invasive endoscopic endonasal skull base surgery has necessitated reproducible and realistic simulators of rare vascular injuries. To assess the face and content validity of an innovative perfusion-based cadaveric model developed to simulate internal carotid artery (ICA) injury during endoscopic surgery. Otolaryngology and neurosurgery trainees attempted 3 consecutive trials of endoscopic control of a parasellar ICA injury, with standardized technical feedback. Time to hemostasis (TTH) and blood loss were trended. All participants completed validated questionnaires using a 5-point Likert scale to assess the domains of confidence gain, face validity, content validity, and curriculum applicability. Among all participants (n = 35), TTH and mean blood loss significantly decreased between first vs second attempt (P = .005), and first vs third attempt (P = .03). Following the first attempt, trainees experienced an average 63% reduction in blood loss and 59% reduction in TTH. In the quartile of most improved participants, average blood loss reduction was 1115 mL (84% reduction) and TTH of 259 s (84% reduction). There were no significant differences between trainees of varying postgraduate year or specialty. Average pre and postprocedural confidence scores were 1.38 and 3.16, respectively (P < .0001). All trainees reported model realism, which achieved mean face validity 4.82 ± 0.41 and content validity 4.88 ± 0.33. The perfusion-based human cadaveric ICA injury model achieves high ratings of face and content validity across all levels of surgical trainees, and enables safe, realistic simulation for standardized skull base simulation and future curriculum development. Objective improvements in performance metrics may translate to improved patient outcomes.

  3. REM sleep complicates period adding bifurcations from monophasic to polyphasic sleep behavior in a sleep-wake regulatory network model for human sleep

    OpenAIRE

    Kalmbach, K.; Booth, V.; Behn, C. G. Diniz

    2017-01-01

    The structure of human sleep changes across development as it consolidates from the polyphasic sleep of infants to the single nighttime sleep period typical in adults. Across this same developmental period, time scales of the homeostatic sleep drive, the physiological drive to sleep that increases with time spent awake, also change and presumably govern the transition from polyphasic to monophasic sleep behavior. Using a physiologically-based, sleep-wake regulatory network model for human sle...

  4. Carotid Artery Screening

    Science.gov (United States)

    ... that look for inherited genetic markers linked to disease, and imaging tests that produce pictures of the inside of the body. These ... a risk factor. Risk factors for carotid artery disease include: age high blood pressure diabetes tobacco smoking high cholesterol coronary artery disease (CAD) obesity ...

  5. Crisis bifurcations in plane Poiseuille flow.

    Science.gov (United States)

    Zammert, Stefan; Eckhardt, Bruno

    2015-04-01

    Many shear flows follow a route to turbulence that has striking similarities to bifurcation scenarios in low-dimensional dynamical systems. Among the bifurcations that appear, crisis bifurcations are important because they cause global transitions between open and closed attractors, or indicate drastic increases in the range of the state space that is covered by the dynamics. We here study exterior and interior crisis bifurcations in direct numerical simulations of transitional plane Poiseuille flow in a mirror-symmetric subspace. We trace the state space dynamics from the appearance of the first three-dimensional exact coherent structures to the transition from an attractor to a chaotic saddle in an exterior crisis. For intermediate Reynolds numbers, the attractor undergoes several interior crises, in which new states appear and intermittent behavior can be observed. The bifurcations contribute to increasing the complexity of the dynamics and to a more dense coverage of state space.

  6. Voltage stability, bifurcation parameters and continuation methods

    Energy Technology Data Exchange (ETDEWEB)

    Alvarado, F.L. [Wisconsin Univ., Madison, WI (United States)

    1994-12-31

    This paper considers the importance of the choice of bifurcation parameter in the determination of the voltage stability limit and the maximum power load ability of a system. When the bifurcation parameter is power demand, the two limits are equivalent. However, when other types of load models and bifurcation parameters are considered, the two concepts differ. The continuation method is considered as a method for determination of voltage stability margins. Three variants of the continuation method are described: the continuation parameter is the bifurcation parameter the continuation parameter is initially the bifurcation parameter, but is free to change, and the continuation parameter is a new `arc length` parameter. Implementations of voltage stability software using continuation methods are described. (author) 23 refs., 9 figs.

  7. Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study) : an interim analysis of a randomised controlled trial

    NARCIS (Netherlands)

    Ederle, Joerg; Dobson, Joanna; Featherstone, Roland L.; Bonati, Leo H.; van der Worp, H. Bart; de Borst, Gert J.; Lo, T. Hauw; Gaines, Peter; Dorman, Paul J.; Macdonald, Sumaira; Lyrer, Philippe A.; Hendriks, Johanna M.; McCollum, Charles; Nederkoorn, Paul J.; Brown, Martin M.; Algra, A.; Bamford, J.; Beard, J.; Bland, M.; Bradbury, A. W.; Brown, M. M.; Clifton, A.; Gaines, P.; Hacke, W.; Halliday, A.; Malik, I.; Mas, J. L.; McGuire, A. J.; Sidhu, P.; Venables, G.; Bradbury, A.; Brown, M. M.; Clifton, A.; Gaines, P.; Collins, R.; Molynewc, A.; Naylor, R.; Warlow, C.; Ferro, J. M.; Thomas, D.; Bonati, L. H.; Coward, L.; Dobson, J.; Ederle, J.; Featherstone, R. F.; Tindall, H.; McCabe, D. J. H.; Wallis, A.; Brooks, M.; Chambers, B.; Chan, A.; Chu, P.; Clark, D.; Dewey, H.; Donnan, G.; Fell, G.; Hoare, M.; Molan, M.; Roberts, A.; Roberts, N.; Beiles, B.; Bladin, C.; Clifford, C.; Fell, G.; Grigg, M.; New, G.; Bell, R.; Bower, S.; Chong, W.; Holt, M.; Saunder, A.; Than, P. G.; Gett, S.; Leggett, D.; McGahan, T.; Quinn, J.; Ray, M.; Wong, A.; Woodruff, P.; Foreman, R.; Schultz, D.; Scroop, R.; Stanley, B.; Allard, B.; Atkinson, N.; Cambell, W.; Davies, S.; Field, P.; Milne, P.; Mitchell, P.; Tress, B.; Yan, B.; Beasley, A.; Dunbabin, D.; Stary, D.; Walker, S.; Cras, P.; d'Archambeau, O.; Hendriks, J. M. H.; Van Schil, P.; Bosiers, M.; Deloose, K.; van Buggenhout, E.; De Letter, J.; Devos, V.; Ghekiere, J.; Vanhooren, G.; Astarci, P.; Hammer, F.; Lacroix, V.; Peeters, A.; Verhelst, R.; DeJaegher, L.; Peeters, A.; Verbist, J.; Blair, J-F; Caron, J. L.; Daneault, N.; Giroux, M-F; Guilbert, F.; Lanthier, S.; Lebrun, L-H; Oliva, V.; Raymond, J.; Roy, D.; Soulez, G.; Weill, A.; Hill, M.; Hu, W.; Hudion, M.; Morrish, W.; Sutherland, G.; Wong, J.; Alback, A.; Harno, H.; Ijas, P.; Kaste, M.; Lepantalo, M.; Mustanoja, S.; Paananen, T.; Porras, M.; Putaala, J.; Railo, M.; Sairanen, T.; Soinne, L.; Vehmas, A.; Vikatmaa, P.; Goertler, M.; Halloul, Z.; Skalej, M.; Brennan, P.; Kelly, C.; Leahy, A.; Moroney, J.; Thornton, J.; Koelemay, M. J. W.; Nederkoorn, P. J.; Reekers, J. A. A.; Roos, Y. B. W. E. M.; Hendriks, J. M.; Koudstaal, P. J.; Pattynama, P. M. T.; van der Lugt, A.; van Dijk, L. C.; van Sambeek, M. R. H. M.; van Urk, H.; Verhagen, H. J. M.; Bruininckx, C. M. A.; de Bruijn, S. F.; Keunen, R.; Knippenberg, B.; Mosch, A.; Treurniet, F.; van Dijk, L.; van Overhagen, H.; Wever, J.; de Beer, F. C.; van den Berg, J. S. P.; van Hasselt, B. A. A. M.; Zeilstra, D. J.; Boiten, J.; van Otterloo, J. C. A. de Mol; de Vries, A. C.; Nieholt, G. J. Lycklama A.; van der Kallen, B. F. W.; Blankensteijn, J. D.; De Leeuw, F. E.; Kool, L. J. Schultze; van der Vliet, J. A.; de Borst, G. J.; de Kort, G. A. P.; Kapelle, L. J.; Lo, T. H.; Mali, W. P. Th M.; Moll, F.; van der Worp, H. Bart; Verhagen, H.; Barber, P. A.; Bourchier, R.; Hill, A.; Holden, A.; Stewart, J.; Bakke, S. J.; Krohg-Sorensen, K.; Skjelland, M.; Tennoe, B.; Bialek, P.; Biejat, Z.; Czepiel, W.; Czlonkowska, A.; Dowzenko, A.; Jedrzejewska, J.; Kobayashi, A.; Lelek, M.; Polanski, J.; Kirbis, J.; Milosevic, Z.; Zvan, B.; Blasco, J.; Chamorro, A.; Macho, J.; Obach, V.; Riambau, V.; San Roman, L.; Branera, J.; Canovas, D.; Estela, Jordi; Gimenez Gaibar, A.; Perendreu, J.; Bjorses, K.; Gottsater, A.; Ivancev, K.; Maetzsch, T.; Sonesson, B.; Berg, B.; Delle, M.; Formgren, J.; Gillgren, P.; Kall, T-B; Konrad, P.; Nyman, N.; Takolander, R.; Andersson, T.; Malmstedt, J.; Soderman, M.; Wahlgren, C.; Wahlgren, N.; Binaghi, S.; Hirt, L.; Michel, P.; Ruchat, P.; Bonati, L. H.; Engelter, S. T.; Fluri, F.; Guerke, L.; Jacob, A. L.; Kirsch, E.; Lyrer, P. A.; Radue, E-W; Stierli, P.; Wasner, M.; Wetzel, S.; Bonvin, C.; Kalangos, A.; Lovblad, K.; Murith, N.; Ruefenacht, D.; Sztajzel, R.; Higgins, N.; Kirkpatrick, P. J.; Martin, P.; Adam, D.; Bell, J.; Bradbury, A. W.; Crowe, P.; Gannon, M.; Henderson, M. J.; Sandler, D.; Shinton, R. A.; Scriven, J. M.; Wilmink, T.; D'Souza, S.; Egun, A.; Guta, R.; Punekar, S.; Seriki, D. M.; Thomson, G.; Brennan, A.; Enevoldson, T. P.; Gilling-Smith, G.; Gould, D. A.; Harris, P. L.; McWilliams, R. G.; Nasser, H-C; White, R.; Prakash, K. G.; Serracino-Inglott, F.; Subramanian, G.; Symth, J. V.; Walker, M. G.; Clarke, M.; Davis, M.; Dixit, S. A.; Dolman, P.; Dyker, A.; Ford, G.; Golkar, A.; Jackson, R.; Jayakrishnan, V.; Lambert, D.; Lees, T.; Louw, S.; Macdonald, S.; Mendelow, A. D.; Rodgers, H.; Rose, J.; Stansby, G.; Wyatt, M.; Baker, T.; Baldwin, N.; Jones, L.; Mitchell, D.; Munro, E.; Thornton, M.; Baker, D.; Davis, N.; Hamilton, G.; McCabe, D.; Platts, A.; Tibballs, J.; Beard, J.; Cleveland, T.; Dodd, D.; Gaines, P.; Lonsdale, R.; Nair, R.; Nassef, A.; Nawaz, S.; Venables, G.; Belli, A.; Clifton, A.; Cloud, G.; Halliday, A.; Markus, H.; McFarland, R.; Morgan, R.; Pereira, A.; Thompson, A.; Chataway, J.; Cheshire, N.; Gibbs, R.; Hammady, M.; Jenkins, M.; Malik, I.; Wolfe, J.; Adiseshiah, M.; Bishop, C.; Brew, S.; Brookes, J.; Brown, M. M.; Jaeger, R.; Kitchen, N.; Ashleigh, R.; Butterfield, S.; Gamble, G. E.; McCollum, C.; Nasim, A.; O'Neill, P.; Wong, J.; Edwards, R. D.; Lees, K. R.; MacKay, A. J.; Moss, J.; Rogers, P.

    2010-01-01

    Background Stents are an alternative treatment to carotid endarterectomy for symptomatic carotid stenosis, but previous trials have not established equivalent safety and efficacy. We compared the safety of carotid artery stenting with that of carotid endarterectomy. Methods The International Carotid

  8. Computational solution of the velocity and wall shear stress distribution inside a left carotid artery under pulsatile flow conditions

    Science.gov (United States)

    Arslan, Nurullah; Turmuş, Hakan

    2014-08-01

    Stroke is still one of the leading causes for death after heart diseases and cancer in all over the world. Strokes happen because an artery that carries blood uphill from the heart to the head is clogged. Most of the time, as with heart attacks, the problem is atherosclerosis, hardening of the arteries, calcified buildup of fatty deposits on the vessel wall. In this study, the fluid dynamic simulations were done in a left carotid bifurcation under the pulsatile flow conditions computationally. Pulsatile flow waveform is given in the paper. In vivo geometry and boundary conditions were obtained from a patient who has stenosis located at external carotid artery (ECA) and internal carotid artery (ICA) of his common carotid artery (CCA). The location of critical flow fields such as low wall shear stress (WSS), stagnation regions and separation regions were detected near the highly stenosed region and at branching region.

  9. Oxidative stress in carotid arteries of patients submitted to carotid endarterectomy. The role of aging process.

    Science.gov (United States)

    Lucas, Márcio Luís; Carraro, Cristina Campos; Belló-Klein, Adriane; Kalil, Antônio Nocchi; Aerts, Newton

    2016-08-01

    To evaluated the role of oxidative stress on aging process in patients submitted to carotid endarterectomy. Twenty patients were divided into two groups: older group (≥ 70 years old); and the younger group (aging is associated with increased concentrations of oxygen species and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity as so as nitrite reduction in human carotid artery specimens. Maybe therapies that block NADPH oxidase activity and enhance nitrite stores would be a good strategy to reduce the effect of oxidative stress in arterial aging.

  10. Carotid revascularization: risks and benefits

    Directory of Open Access Journals (Sweden)

    O'Brien M

    2014-07-01

    Full Text Available Marlene O'Brien, Ankur Chandra Department of Surgery, Division of Vascular Surgery, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA Abstract: Despite a decline during the recent decades in stroke-related death, the incidence of stroke has remained unchanged or slightly increased, and extracranial carotid artery stenosis is implicated in 20%–30% of all strokes. Medical therapy and risk factor modification are first-line therapies for all patients with carotid occlusive disease. Evidence for the treatment of patients with symptomatic carotid stenosis greater than 70% with either carotid artery stenting (CAS or carotid endarterectomy (CEA is compelling, and several trials have demonstrated a benefit to carotid revascularization in the symptomatic patient population. Asymptomatic carotid stenosis is more controversial, with the largest trials only demonstrating a 1% per year risk stroke reduction with CEA. Although there are sufficient data to advocate for aggressive medical therapy as the primary mode of treatment for asymptomatic carotid stenosis, there are also data to suggest that certain patient populations will benefit from a stroke risk reduction with carotid revascularization. In the United States, consensus and practice guidelines dictate that CEA is reasonable in patients with high-grade asymptomatic stenosis, a reasonable life expectancy, and perioperative risk of less than 3%. Regarding CAS versus CEA, the best-available evidence demonstrates no difference between the two procedures in early perioperative stroke, myocardial infarction, or death, and no difference in 4-year ipsilateral stroke risk. However, because of the higher perioperative risks of stroke in patients undergoing CAS, particularly in symptomatic, female, or elderly patients, it is difficult to recommend CAS over CEA except in populations with prohibitive cardiac risk, previous carotid surgery, or prior neck radiation. Current treatment

  11. Carotid endarterectomy: The procedure of choice for carotid stenosis

    Directory of Open Access Journals (Sweden)

    B.V. Savitr Sastri

    2013-01-01

    Full Text Available Ischemic stroke is the commonest cause of neurological morbidity and mortality. Carotid endarterectomy has been shown to be beneficial in preventing ischemic strokes in patients with significant stenosis of the carotid artery, both in symptomatic and asymptomatic patients. Carotid artery stenting has been proposed as an alternative to CEA for this population. This paper reviews the available literature on carotid endarterectomy comparing it to the best medical therapy and carotid artery stenting in the prevention of ischemic strokes in patients with carotid stenosis. The use of newer imaging techniques and tools to redefine the existing idea of "asymptomatic" stenosis and post procedural strokes has also been reviewed. We present a concise review of existing data that shows unequivocally that endarterectomy still remains superior to stenting and best medical therapy as of now.

  12. Semiclassical catastrophe theory of simple bifurcations

    Science.gov (United States)

    Magner, A. G.; Arita, K.

    2017-10-01

    The Fedoriuk-Maslov catastrophe theory of caustics and turning points is extended to solve the bifurcation problems by the improved stationary phase method (ISPM). The trace formulas for the radial power-law (RPL) potentials are presented by the ISPM based on the second- and third-order expansion of the classical action near the stationary point. A considerable enhancement of contributions of the two orbits (pair consisting of the parent and newborn orbits) at their bifurcation is shown. The ISPM trace formula is proposed for a simple bifurcation scenario of Hamiltonian systems with continuous symmetries, where the contributions of the bifurcating parent orbits vanish upon approaching the bifurcation point due to the reduction of the end-point manifold. This occurs since the contribution of the parent orbits is included in the term corresponding to the family of the newborn daughter orbits. Taking this feature into account, the ISPM level densities calculated for the RPL potential model are shown to be in good agreement with the quantum results at the bifurcations and asymptotically far from the bifurcation points.

  13. Attractivity and bifurcation for nonautonomous dynamical systems

    CERN Document Server

    Rasmussen, Martin

    2007-01-01

    Although, bifurcation theory of equations with autonomous and periodic time dependence is a major object of research in the study of dynamical systems since decades, the notion of a nonautonomous bifurcation is not yet established. In this book, two different approaches are developed which are based on special definitions of local attractivity and repulsivity. It is shown that these notions lead to nonautonomous Morse decompositions, which are useful to describe the global asymptotic behavior of systems on compact phase spaces. Furthermore, methods from the qualitative theory for linear and nonlinear systems are derived, and nonautonomous counterparts of the classical one-dimensional autonomous bifurcation patterns are developed.

  14. Angioplasty and stent placement - carotid artery

    Science.gov (United States)

    ... and stenting; CAS; Angioplasty - carotid artery; Carotid artery stenosis - angioplasty; ... Stenting versus endarterectomy for treatment of carotid-arery stenosis. N Engl J Med . 2010;363(1):11- ...

  15. Carotid artery stenosis -- self-care

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000717.htm Carotid artery stenosis - self-care To use the sharing features on ... feel their pulse under your jawline. Carotid artery stenosis occurs when the carotid arteries become narrowed or ...

  16. Spontaneous carotid dissection

    Directory of Open Access Journals (Sweden)

    Carolina Dutra Queiroz Flumignan

    Full Text Available Summary Carotid dissection is a rare occurrence but it is the main cause of stroke in individuals aged less than 45 years, and can be the etiology in up to 25% of strokes in young adults. We report a case with classic image of ying yang on vascular ultrasound, which was treated according to the best available medical evidence, yielding a favorable outcome.

  17. (18)F-FDG imaging of human atherosclerotic carotid plaques reflects gene expression of the key hypoxia marker HIF-1α

    DEFF Research Database (Denmark)

    Pedersen, Sune Folke; Græbe, Martin; Hag, Anne Mette F

    2013-01-01

    To investigate the association between gene expression of key molecular markers of hypoxia and inflammation in atherosclerotic carotid lesions with 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) uptake as determined clinically by positron emission tomography (PET). Studies using PET have demonstra......To investigate the association between gene expression of key molecular markers of hypoxia and inflammation in atherosclerotic carotid lesions with 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) uptake as determined clinically by positron emission tomography (PET). Studies using PET have...... between hypoxia and glucose metabolism in vivo. The marker of inflammation CD68 is also associated with (18)F-FDG-uptake (SUVmax). As CD68 and HIF-1α gene expression co-variate their information is overlapping....

  18. On a quasi-periodic Hopf bifurcation

    NARCIS (Netherlands)

    Braaksma, B.L.J.; Broer, H.W.

    1987-01-01

    In this paper we study quasi-periodic Hopf bifurcations for the model problem of a quasi-periodically forced oscillator, where the frequencies remain fixed. For this purpose we first consider Stoker's problem for small damping.

  19. Bifurcation and instability problems in vortex wakes

    DEFF Research Database (Denmark)

    Aref, Hassan; Brøns, Morten; Stremler, Mark A.

    2007-01-01

    A number of instability and bifurcation problems related to the dynamics of vortex wake flows are addressed using various analytical tools and approaches. We discuss the bifurcations of the streamline pattern behind a bluff body as a vortex wake is produced, a theory of the universal Strouhal......-Reynolds number relation for vortex wakes, the bifurcation diagram for "exotic" wake patterns behind an oscillating cylinder first determined experimentally by Williamson & Roshko, and the bifurcations in topology of the streamlines pattern in point vortex streets. The Hamiltonian dynamics of point vortices...... in a periodic strip is considered. The classical results of von Kármán concerning the structure of the vortex street follow from the two-vortices-in-a-strip problem, while the stability results follow largely from a four-vortices-in-a-strip analysis. The three-vortices-in-a-strip problem is argued...

  20. Bifurcating optical pattern recognition in photorefractive crystals

    Science.gov (United States)

    Liu, Hua-Kuang

    1993-01-01

    A concept of bifurcating optical pattern rocognizer (BIOPAR) is described and demonstrated experimentally, using barium titanate crystal. When an input is applied to BIOPAR, the output may be directed to two ports.

  1. Transcarotid Artery Endovascular Reconstruction of the Aortic Arch by Modified Bifurcated Stent Graft for Stanford Type A Dissection

    Directory of Open Access Journals (Sweden)

    Wei Guo

    2007-10-01

    Full Text Available A 40-year-old man with Stanford type B dissection underwent his first endovascular repair (EVAR in April 2004 by Talent thoracic stent graft. He had an uncomplicated recovery and maintained good blood pressure control. However, a new retrograde dissection appeared in September 2004. The new dissection involved his aortic arch and ascending thoracic aorta to the opening of the coronary arteries. To reconstruct the aortic arch, bypasses between the right common carotid artery (RCCA, left common carotid artery and left subclavian artery were performed before endovascular repair. A modified bifurcated Talent stent graft was deployed from the RCCA to the ascending thoracic aorta with a long limb in the innominate artery and a short limb in the aortic arch. A further two pieces of graft were deployed via the common femoral artery. The ascending thoracic aorta and aortic arch were reconstructed completely by the bifurcated stent graft. The final angiography confirmed that there was good stent graft configuration, normal blood flow, and stable haemodynamics. No endoleak or other major complications were encountered. This result indicated that it is possible to reconstruct the aortic arch with a bifurcated stent graft and could be a new endovascular repair model for complex thoracic aortic aneurysm and dissection.

  2. Uniform semiclassical approximations for umbilic bifurcation catastrophes

    CERN Document Server

    Main, J

    1998-01-01

    Gutzwiller's trace formula for the semiclassical density of states diverges at the bifurcation points of periodic orbits and has to be replaced with uniform semiclassical approximations. We present a method to derive these expressions from the standard representations of the elementary catastrophes and to directly relate the uniform solutions to classical periodic orbit parameters. The method is simple even for ungeneric bifurcations with corank 2 such as the umbilic catastrophes. We demonstrate the technique on a hyperbolic umbilic in the diamagnetic Kepler problem.

  3. Discretization analysis of bifurcation based nonlinear amplifiers

    Directory of Open Access Journals (Sweden)

    S. Feldkord

    2017-09-01

    Full Text Available Recently, for modeling biological amplification processes, nonlinear amplifiers based on the supercritical Andronov–Hopf bifurcation have been widely analyzed analytically. For technical realizations, digital systems have become the most relevant systems in signal processing applications. The underlying continuous-time systems are transferred to the discrete-time domain using numerical integration methods. Within this contribution, effects on the qualitative behavior of the Andronov–Hopf bifurcation based systems concerning numerical integration methods are analyzed. It is shown exemplarily that explicit Runge–Kutta methods transform the truncated normalform equation of the Andronov–Hopf bifurcation into the normalform equation of the Neimark–Sacker bifurcation. Dependent on the order of the integration method, higher order terms are added during this transformation.A rescaled normalform equation of the Neimark–Sacker bifurcation is introduced that allows a parametric design of a discrete-time system which corresponds to the rescaled Andronov–Hopf system. This system approximates the characteristics of the rescaled Hopf-type amplifier for a large range of parameters. The natural frequency and the peak amplitude are preserved for every set of parameters. The Neimark–Sacker bifurcation based systems avoid large computational effort that would be caused by applying higher order integration methods to the continuous-time normalform equations.

  4. Discretization analysis of bifurcation based nonlinear amplifiers

    Science.gov (United States)

    Feldkord, Sven; Reit, Marco; Mathis, Wolfgang

    2017-09-01

    Recently, for modeling biological amplification processes, nonlinear amplifiers based on the supercritical Andronov-Hopf bifurcation have been widely analyzed analytically. For technical realizations, digital systems have become the most relevant systems in signal processing applications. The underlying continuous-time systems are transferred to the discrete-time domain using numerical integration methods. Within this contribution, effects on the qualitative behavior of the Andronov-Hopf bifurcation based systems concerning numerical integration methods are analyzed. It is shown exemplarily that explicit Runge-Kutta methods transform the truncated normalform equation of the Andronov-Hopf bifurcation into the normalform equation of the Neimark-Sacker bifurcation. Dependent on the order of the integration method, higher order terms are added during this transformation.A rescaled normalform equation of the Neimark-Sacker bifurcation is introduced that allows a parametric design of a discrete-time system which corresponds to the rescaled Andronov-Hopf system. This system approximates the characteristics of the rescaled Hopf-type amplifier for a large range of parameters. The natural frequency and the peak amplitude are preserved for every set of parameters. The Neimark-Sacker bifurcation based systems avoid large computational effort that would be caused by applying higher order integration methods to the continuous-time normalform equations.

  5. AN ULTRASONOGRAPHIC STUDY OF CAROTID ARTERY PATHOLOGY IN ISCHAEMIC STROKE PATIENTS

    Directory of Open Access Journals (Sweden)

    Puthiya Maliyakkal

    2016-03-01

    Full Text Available BACKGROUND Majority of ischaemic strokes are due to extracranial carotid artery disease. Ultrasonography of the carotid arteries is easily available, cost-effective noninvasive method of evaluation in preventing ischaemic strokes. OBJECTIVES To evaluate the carotid artery pathology, and grade the stenotic lesions by ultrasonography in ischaemic stroke patients. MATERIAL AND METHODS In 25 patients of clinically diagnosed cerebrovascular insufficiency, carotid and vertebral arteries on both sides were examined. The site, size, echogenicity, luminal narrowing and velocity changes at the site of atherosclerotic plaque was recorded. The observations in percentages were compared and analysed. RESULTS Hemiparesis was the commonest presenting complaint. Among these 25 patients, 58% of them had atheromatous plaque. Smoking had a strong association with the development of plaque. 64% of these patients with atheromatous plaque were males with a sex ratio of 1.8:1, 57% of plaques were found at carotid bifurcation predominantly on left side, 57% of these plaques had significant stenosis and one had complete occlusion. Predominant type of these plaque were strongly echogenic with calcification (52%, 35% of these patients had a PSV ratio of 2-4 and 14% >4. CONCLUSION The study showed atheromatous plaque changes with significant stenosis among cerebrovascular insufficiency patients. The findings were consistent with the other studies.

  6. Simple or Complex Stenting for Bifurcation Coronary Lesions: A Patient-Level Pooled-Analysis of the Nordic Bifurcation Study and the British Bifurcation Coronary Study

    DEFF Research Database (Denmark)

    Behan, Miles W; Holm, Niels Ramsing; Curzen, Nicholas P

    2011-01-01

    Background— Controversy persists regarding the correct strategy for bifurcation lesions. Therefore, we combined the patient-level data from 2 large trials with similar methodology: the NORDIC Bifurcation Study (NORDIC I) and the British Bifurcation Coronary Study (BBC ONE). Methods and Results— B...

  7. Studies on the Existence of Unstable Oscillatory Patterns Bifurcating from Hopf Bifurcations in a Turing Model

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2014-01-01

    Full Text Available We revisit a homogeneous reaction-diffusion Turing model subject to the Neumann boundary conditions in the one-dimensional spatial domain. With the help of the Hopf bifurcation theory applicable to the reaction-diffusion equations, we are capable of proving the existence of Hopf bifurcations, which suggests the existence of spatially homogeneous and nonhomogeneous periodic solutions of this particular system. In particular, we also prove that the spatial homogeneous periodic solutions bifurcating from the smallest Hopf bifurcation point of the system are always unstable. This together with the instability results of the spatially nonhomogeneous periodic solutions by Yi et al., 2009, indicates that, in this model, all the oscillatory patterns from Hopf bifurcations are unstable.

  8. Quantification of carotid plaque lipid content with magnetic resonance T2 mapping in patients undergoing carotid endarterectomy.

    Science.gov (United States)

    Alkhalil, Mohammad; Biasiolli, Luca; Chai, Joshua T; Galassi, Francesca; Li, Linqing; Darby, Christopher; Halliday, Alison; Hands, Linda; Magee, Timothy; Perkins, Jeremy; Sideso, Ed; Jezzard, Peter; Robson, Matthew D; Handa, Ashok; Choudhury, Robin P

    2017-01-01

    Techniques to stratify subgroups of patients with asymptomatic carotid artery disease are urgently needed to guide decisions on optimal treatment. Reliance on estimates of % luminal stenosis has not been effective, perhaps because that approach entirely disregards potentially important information on the pathological process in the wall of the artery. Since plaque lipid is a key determinant of plaque behaviour we used a newly validated, high-sensitivity T2-mapping MR technique for a systematic survey of the quantity and distribution of plaque lipid in patients undergoing endarterectomy. Lipid percentage was quantified in 50 carotid endarterectomy patients. Lipid distribution was tested, using two imaging indices (contribution of the largest lipid deposit towards total lipid (LLD %) and a newly-developed LAI 'lipid aggregation index'). The bifurcation contained maximal lipid volume. Lipid percentage was higher in symptomatic vs. asymptomatic patients with degree of stenosis (DS ≥ 50%) and in the total cohort (P = 0.013 and P = 0.005, respectively). Both LLD % and LAI was higher in symptomatic patients (P = 0.028 and P = 0.018, respectively), suggesting that for a given plaque lipid volume, coalesced deposits were more likely to be associated with symptomatic events. There was no correlation between plaque volume or lipid content and degree of luminal stenosis measured on ultrasound duplex (r = -0.09, P = 0.53 and r = -0.05, P = 0.75), respectively. However, there was a strong correlation in lipid between left and right carotid arteries (r = 0.5, P carotid plaque. Importantly, plaque lipid content was not related to the degree of luminal stenosis assessed by ultrasound. Determination of plaque lipid content may prove useful for stratification of asymptomatic patients, including selection of optimal invasive treatments.

  9. Intima-Media Thickness in the Carotid and Femoral Arteries for Detection of Arteriosclerosis in Human Immunodeficiency Virus-Positive Individuals.

    Science.gov (United States)

    Godoi, Emmanuelle Tenório Albuquerque Madruga; Brandt, Carlos Teixeira; Lacerda, Heloisa Ramos; Godoi, Jocelene Tenório Albuquerque Madruga; Oliveira, Dinaldo Cavalcanti de; Costa, Gabriela Farias Araujo Sousa; Santos Junior, Gerson Gomes Dos; Leite, Kaliene Maria Estevão; Godoi, Juannicelle Tenório Albuquerque Madruga; Vasconcelos, Adriana Ferraz de

    2017-01-01

    The prevalence of atherosclerosis is higher in HIV-positive people, who also experience it earlier than the general population. To assess and compare the prevalence of atherosclerosis evaluated by the intima-media thickness of carotid and femoral arteries, and by the ankle-brachial pressure index (ABPI) in HIV patients treated or not treated with protease inhibitors (PIs) and controls. Eighty HIV+ subjects (40 using PIs and 40 not using PIs) and 65 controls were included in the study. Atherosclerosis was diagnosed by (carotid and femoral) ITM measurement and ABPI. Classical risk factors for atherosclerosis and HIV were compared between the groups by statistical tests. A p ≤ 0.05 was considered significant. An IMT > P75 or the presence of plaque was higher in the HIV+ than in the control group (37.5% vs 19%, p = 0.04). Comparative analysis showed a significant difference (p=0.014) in carotid IMT between HIV+ with PIs (0.71 ± 0.28 mm), without PIs 0.63 ± 0.11 mm and, and controls (0.59 ± 0.11 mm). There was no significant difference in femoral IMT between the groups or in ABPI between HIV+ subjects and controls. However, a significant difference (p=0.015) was found between HIV+ patients not treated with PIs (1.17 [1.08 - 1.23]), and controls 1.08 [1.07 - 1.17]). In HIV patients, atherosclerosis is more prevalent and seems to occur earlier with particular characteristics compared with HIV-negative subjects.

  10. A clear map of the lower cranial nerves at the superior carotid triangle.

    Science.gov (United States)

    Cavalcanti, Daniel D; Garcia-Gonzalez, Ulises; Agrawal, Abhishek; Tavares, Paulo L M S; Spetzler, Robert F; Preul, Mark C

    2010-07-01

    The lower cranial nerves must be identified to avoid iatrogenic injury during skull base and high cervical approaches. Prompt recognition of these structures using basic landmarks could reduce surgical time and morbidity. The anterior triangle of the neck was dissected in 30 cadaveric head sides. The most superficial segments of the glossopharyngeal, vagus and its superior laryngeal nerves, accessory, and hypoglossal nerves were exposed and designated into smaller anatomic triangles. The midpoint of each nerve segment inside the triangles was correlated to the angle of the mandible (AM), mastoid tip (MT), and bifurcation of the common carotid artery. A triangle bounded by the styloglossus muscle, external carotid artery, and facial artery housed the glossopharyngeal nerve. This nerve segment was 0.06 ± 0.71 cm posterior to the AM and 2.50 ± 0.59 cm inferior to the MT. The vagus nerve ran inside the carotid sheath posterior to internal carotid artery and common carotid artery bifurcation in 48.3% of specimens. A triangle formed by the posterior belly of digastric muscle, sternocleidomastoid muscle, and internal jugular vein housed the accessory nerve, 1.90 ± 0.60 cm posterior to the AM and 2.30 ± 0.57 cm inferior to the MT. A triangle outlined by the posterior belly of digastric muscle, internal jugular vein, and common facial vein housed the hypoglossal nerve, which was 0.82 ± 0.84 cm posterior to the AM and 3.64 ± 0.70 cm inferior to the MT. Comprehensible landmarks can be defined to help expose the lower cranial nerves to avoid injury to this complex region. Copyright © 2010 Elsevier Inc. All rights reserved.

  11. Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): an interim analysis of a randomised controlled trial.

    NARCIS (Netherlands)

    Ederle, J.; Dobson, J.; Featherstone, R.L.; Bonati, L.H.; Worp, H.B. van der; Borst, G.J. de; Lo, T.H.; Gaines, P.; Dorman, P.J.; Macdonald, S.; Lyrer, P.A.; Hendriks, J.M.; McCollum, C.; Nederkoorn, P.J.; Brown, M.M.; Blankensteijn, J.D.; Leeuw, F.E. de; Kool, L.J.; Vliet, J.A. van der

    2010-01-01

    BACKGROUND: Stents are an alternative treatment to carotid endarterectomy for symptomatic carotid stenosis, but previous trials have not established equivalent safety and efficacy. We compared the safety of carotid artery stenting with that of carotid endarterectomy. METHODS: The International

  12. Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): an interim analysis of a randomised controlled trial.

    LENUS (Irish Health Repository)

    Ederle, Jörg

    2010-03-20

    Stents are an alternative treatment to carotid endarterectomy for symptomatic carotid stenosis, but previous trials have not established equivalent safety and efficacy. We compared the safety of carotid artery stenting with that of carotid endarterectomy.

  13. Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): an interim analysis of a randomised controlled trial

    NARCIS (Netherlands)

    Ederle, Jörg; Dobson, Joanna; Featherstone, Roland L.; Bonati, Leo H.; van der Worp, H. Bart; de Borst, Gert J.; Lo, T. Hauw; Gaines, Peter; Dorman, Paul J.; Macdonald, Sumaira; Lyrer, Philippe A.; Hendriks, Johanna M.; McCollum, Charles; Nederkoorn, Paul J.; Brown, Martin M.; Algra, A.; Bamford, J.; Beard, J.; Bland, M.; Bradbury, A. W.; Brown, M. M.; Clifton, A.; Gaines, P.; Collins, R.; Molyneux, A.; Naylor, R.; Warlow, C.; Ferro, J. M.; Thomas, D.; Bonati, L. H.; Coward, L.; Dobson, J.; Ederle, J.; Featherstone, R. F.; Tindall, H.; McCabe, D. J. H.; Wallis, A.; Brooks, M.; Chambers, B.; Chan, A.; Chu, P.; Clark, D.; Dewey, H.; Donnan, G.; Fell, G.; Hoare, M.; Molan, M.; Roberts, A.; Roberts, N.; Beiles, B.; Bladin, C.; Clifford, C.; Grigg, M.; New, G.; Bell, R.; Bower, S.; Chong, W.; Holt, M.; Saunder, A.; Than, P. G.; Gett, S.; Leggett, D.; McGahan, T.; Quinn, J.; Ray, M.; Wong, A.; Woodruff, P.; Foreman, R.; Schultz, D.; Scroop, R.; Stanley, B.; Allard, B.; Atkinson, N.; Cambell, W.; Davies, S.; Field, P.; Milne, P.; Mitchell, P.; Tress, B.; Yan, B.; Beasley, A.; Dunbabin, D.; Stary, D.; Walker, S.; Cras, P.; d'Archambeau, O.; Hendriks, J. M. H.; van Schil, P.; St Blasius, A. Z.; Bosiers, M.; Deloose, K.; van Buggenhout, E.; de Letter, J.; Devos, V.; Ghekiere, J.; Vanhooren, G.; Astarci, P.; Hammer, F.; Lacroix, V.; Peeters, A.; Verbist, J.; Blair, J.-F.; Caron, J. L.; Daneault, N.; Giroux, M.-F.; Guilbert, F.; Lanthier, S.; Lebrun, L.-H.; Oliva, V.; Raymond, J.; Roy, D.; Soulez, G.; Weill, A.; Hill, M.; Hu, W.; Hudion, M.; Morrish, W.; Sutherland, G.; Wong, J.; Albäck, A.; Harno, H.; Ijäs, P.; Kaste, M.; Lepäntalo, M.; Mustanoja, S.; Paananen, T.; Porras, M.; Putaala, J.; Railo, M.; Sairanen, T.; Soinne, L.; Vehmas, A.; Vikatmaa, P.; Goertler, M.; Halloul, Z.; Skalej, M.; Brennan, P.; Kelly, C.; Leahy, A.; Moroney, J.; Thornton, J.; Koelemay, M. J. W.; Reekers, J. A. A.; Roos, Y. B. W. E. M.; Hendriks, J. M.; Koudstaal, P. J.; Pattynama, P. M. T.; van der Lugt, A.; van Dijk, L. C.; van Sambeek, M. R. H. M.; van Urk, H.; Verhagen, H. J. M.; Bruijninckx, C. M. A.; de Bruijn, S. F.; Keunen, R.; Knippenberg, B.; Mosch, A.; Treurniet, F.; van Dijk, L.; van Overhagen, H.; Wever, J.; de Beer, F. C.; van den Berg, J. S. P.; van Hasselt, B. A. A. M.; Zeilstra, D. J.; Boiten, J.; van Otterloo, J. C. A. de Mol; de Vries, A. C.; Lycklama a Nijeholt, G. J.; van der Kallen, B. F. W.; Blankensteijn, J. D.; de Leeuw, F. E.; Kool, L. J. Schultze; van der Vliet, J. A.; de Borst, G. J.; de Kort, G. A. P.; Kapelle, L. J.; Lo, T. H.; Mali, W. P. Th M.; Moll, F.; van der Worp, H. B.; Verhagen, H.; Barber, P. A.; Bourchier, R.; Hill, A.; Holden, A.; Stewart, J.; Bakke, S. J.; Krohg-Sørensen, K.; Skjelland, M.; Tennøe, B.; Bialek, P.; Biejat, Z.; Czepiel, W.; Czlonkowska, A.; Dowzenko, A.; Jedrzejewska, J.; Kobayashi, A.; Lelek, M.; Polanski, J.; Kirbis, J.; Milosevic, Z.; Zvan, B.; Blasco, J.; Chamorro, A.; Macho, J.; Obach, V.; Riambau, V.; San Roman, L.; Branera, J.; Canovas, D.; Estela, Jordi; Gaibar, A. Gimenez; Perendreu, J.; Björses, K.; Gottsater, A.; Ivancev, K.; Maetzsch, T.; Sonesson, B.; Berg, B.; Delle, M.; Formgren, J.; Gillgren, P.; Kall, T.-B.; Konrad, P.; Nyman, N.; Takolander, R.; Andersson, T.; Malmstedt, J.; Soderman, M.; Wahlgren, C.; Wahlgren, N.; Binaghi, S.; Hirt, L.; Michel, P.; Ruchat, P.; Engelter, S. T.; Fluri, F.; Guerke, L.; Jacob, A. L.; Kirsch, E.; Lyrer, P. A.; Radue, E.-W.; Stierli, P.; Wasner, M.; Wetzel, S.; Bonvin, C.; Kalangos, A.; Lovblad, K.; Murith, M.; Ruefenacht, D.; Sztajzel, R.; Higgins, N.; Kirkpatrick, P. J.; Martin, P.; Varty, K.; Adam, D.; Bell, J.; Crowe, P.; Gannon, M.; Henderson, M. J.; Sandler, D.; Shinton, R. A.; Scriven, J. M.; Wilmink, T.; D'Souza, S.; Egun, A.; Guta, R.; Punekar, S.; Seriki, D. M.; Thomson, G.; Brennan, J. A.; Enevoldson, T. P.; Gilling-Smith, G.; Gould, D. A.; Harris, P. L.; McWilliams, R. G.; Nasser, H.-C.; White, R.; Prakash, K. G.; Serracino-Inglott, F.; Subramanian, G.; Symth, J. V.; Walker, M. G.; Clarke, M.; Davis, M.; Dixit, S. A.; Dorman, P.; Dyker, A.; Ford, G.; Golkar, A.; Jackson, R.; Jayakrishnan, V.; Lambert, D.; Lees, T.; Louw, S.; Macdonald, S.; Mendelow, A. D.; Rodgers, H.; Rose, J.; Stansby, G.; Wyatt, M.; Baker, T.; Baldwin, N.; Jones, L.; Mitchell, D.; Munro, E.; Thornton, M.; Baker, D.; Davis, N.; Hamilton, G.; McCabe, D.; Platts, A.; Tibballs, J.; Cleveland, T.; Dodd, D.; Lonsdale, R.; Nair, R.; Nassef, A.; Nawaz, S.; Venables, G.; Belli, A.; Cloud, G.; Halliday, A.; Markus, H.; McFarland, R.; Morgan, R.; Pereira, A.; Thompson, A.; Chataway, J.; Cheshire, N.; Gibbs, R.; Hammady, M.; Jenkins, M.; Malik, I.; Wolfe, J.; Adiseshiah, M.; Bishop, C.; Brew, S.; Brookes, J.; Jäger, R.; Kitchen, N.; Ashleigh, R.; Butterfield, S.; Gamble, G. E.; McCollum, C.; Nasim, A.; O'Neill, P.; Edwards, R. D.; Lees, K. R.; MacKay, A. J.; Moss, J.

    2010-01-01

    BACKGROUND: Stents are an alternative treatment to carotid endarterectomy for symptomatic carotid stenosis, but previous trials have not established equivalent safety and efficacy. We compared the safety of carotid artery stenting with that of carotid endarterectomy. METHODS: The International

  14. Variations in branching pattern of external carotid artery in a black ...

    African Journals Online (AJOL)

    Two hundred and twenty-four common carotid arteries of 112 black adult Kenyans were exposed by cadaveric dissection at Department of Human Anatomy, University of Nairobi, Kenya. The sternocleidomastoid muscle and body of mandible were removed and the external carotid artery and its branches exposed.

  15. Clipping Surgery for Paraclinoid Carotid Aneurysm.

    Science.gov (United States)

    Horiuchi, Tetsuyoshi; Yamamoto, Yasunaga; Suzuki, Yota; Kobayashi, Masayoshi; Ichinose, Shunsuke; Hongo, Kazuhiro

    2016-01-01

    Paraclinoid carotid aneurysm is widely treated with coil embolization. However, all paraclinoid carotid aneurysms cannot be obliterated by the endovascular approach. Our direct surgical procedure was presented. The clinical data of surgically treated paraclinoid carotid aneurysms were retrospectively reviewed. One hundred ninety paraclinoid carotid aneurysms in 181 patients were directly obliterated at the Shinshu University Hospital and its affiliated hospitals between 1991 and 2013. Direct surgical repair of the paraclinoid carotid aneurysm is still useful, even in the era of endovascular treatment.

  16. The dynamo bifurcation in rotating spherical shells

    CERN Document Server

    Morin, Vincent; 10.1142/S021797920906378X

    2010-01-01

    We investigate the nature of the dynamo bifurcation in a configuration applicable to the Earth's liquid outer core, i.e. in a rotating spherical shell with thermally driven motions. We show that the nature of the bifurcation, which can be either supercritical or subcritical or even take the form of isola (or detached lobes) strongly depends on the parameters. This dependence is described in a range of parameters numerically accessible (which unfortunately remains remote from geophysical application), and we show how the magnetic Prandtl number and the Ekman number control these transitions.

  17. Bifurcation structure of a model of bursting pancreatic cells

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Lading, B.; Yanchuk, S.

    2001-01-01

    One- and two-dimensional bifurcation studies of a prototypic model of bursting oscillations in pancreatic P-cells reveal a squid-formed area of chaotic dynamics in the parameter plane, with period-doubling bifurcations on one side of the arms and saddle-node bifurcations on the other. The transit......One- and two-dimensional bifurcation studies of a prototypic model of bursting oscillations in pancreatic P-cells reveal a squid-formed area of chaotic dynamics in the parameter plane, with period-doubling bifurcations on one side of the arms and saddle-node bifurcations on the other....... The transition from this structure to the so-called period-adding structure is found to involve a subcritical period-doubling bifurcation and the emergence of type-III intermittency. The period-adding transition itself is not smooth but consists of a saddle-node bifurcation in which (n + 1)-spike bursting...

  18. Codimension-2 bifurcations of the Kaldor model of business cycle

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiaoqin P., E-mail: xpaul_wu@yahoo.co [Department of Mathematics, Computer and Information Sciences, Mississippi Valley State University, Itta Bena, MS 38941 (United States)

    2011-01-15

    Research highlights: The conditions are given such that the characteristic equation may have purely imaginary roots and double zero roots. Purely imaginary roots lead us to study Hopf and Bautin bifurcations and to calculate the first and second Lyapunov coefficients. Double zero roots lead us to study Bogdanov-Takens (BT) bifurcation. Bifurcation diagrams for Bautin and BT bifurcations are obtained by using the normal form theory. - Abstract: In this paper, complete analysis is presented to study codimension-2 bifurcations for the nonlinear Kaldor model of business cycle. Sufficient conditions are given for the model to demonstrate Bautin and Bogdanov-Takens (BT) bifurcations. By computing the first and second Lyapunov coefficients and performing nonlinear transformation, the normal forms are derived to obtain the bifurcation diagrams such as Hopf, homoclinic and double limit cycle bifurcations. Some examples are given to confirm the theoretical results.

  19. Intracerebral haemorrhage after carotid endarterectomy

    DEFF Research Database (Denmark)

    Schroeder, T; Sillesen, H; Boesen, J

    1987-01-01

    Among 662 consecutive carotid endarterectomies eight cases of postoperative ipsilateral intracerebral haemorrhage were identified, occurring into brain areas which, preoperatively were without infarction. As blood pressures across the stenosis were routinely measured during surgery, the internal...

  20. Secondary bifurcation for a nonlocal Allen-Cahn equation

    Science.gov (United States)

    Kuto, Kousuke; Mori, Tatsuki; Tsujikawa, Tohru; Yotsutani, Shoji

    2017-09-01

    This paper studies the Neumann problem of a nonlocal Allen-Cahn equation in an interval. A main result finds a symmetry breaking (secondary) bifurcation point on the bifurcation curve of solutions with odd-symmetry. Our proof is based on a level set analysis for the associated integral map. A method using the complete elliptic integrals proves the uniqueness of secondary bifurcation point. We also show some numerical simulations concerning the global bifurcation structure.

  1. Estimation of an image derived input function with MR-defined carotid arteries in FDG-PET human studies using a novel partial volume correction method

    DEFF Research Database (Denmark)

    Sari, Hasan; Erlandsson, Kjell; Law, Ian

    2017-01-01

    segmentation of the carotid arteries from MR images. The simulation study results showed that at least 92% of the true intensity could be recovered after the partial volume correction. Results from 19 subjects showed that the mean cerebral metabolic rate of glucose calculated using arterial samples and partial...... volume corrected image derived input function were 26.9 and 25.4 mg/min/100 g, respectively, for the grey matter and 7.2 and 6.7 mg/min/100 g for the white matter. No significant difference in the estimated cerebral metabolic rate of glucose values was observed between arterial samples and corrected......Kinetic analysis of (18)F-fluorodeoxyglucose positron emission tomography data requires an accurate knowledge the arterial input function. The gold standard method to measure the arterial input function requires collection of arterial blood samples and is an invasive method. Measuring an image...

  2. Dynamic Analysis of the Carotid-Kundalini Map

    Science.gov (United States)

    Wang, Xingyuan; Liang, Qingyong; Meng, Juan

    The nature of the fixed points of the Carotid-Kundalini (C-K) map was studied and the boundary equation of the first bifurcation of the C-K map in the parameter plane is presented. Using the quantitative criterion and rule of chaotic system, the paper reveals the general features of the C-K Map transforming from regularity to chaos. The following conclusions are obtained: (i) chaotic patterns of the C-K map may emerge out of double-periodic bifurcation; (ii) the chaotic crisis phenomena are found. At the same time, the authors analyzed the orbit of critical point of the complex C-K Map and put forward the definition of Mandelbrot-Julia set of the complex C-K Map. The authors generalized the Welstead and Cromer's periodic scanning technique and using this technology constructed a series of the Mandelbrot-Julia sets of the complex C-K Map. Based on the experimental mathematics method of combining the theory of analytic function of one complex variable with computer aided drawing, we investigated the symmetry of the Mandelbrot-Julia set and studied the topological inflexibility of distribution of the periodic region in the Mandelbrot set, and found that the Mandelbrot set contains abundant information of the structure of Julia sets by finding the whole portray of Julia sets based on Mandelbrot set qualitatively.

  3. Symmetric/asymmetric bifurcation behaviours of a bogie system

    DEFF Research Database (Denmark)

    Xue-jun, Gao; Ying-hui, Li; Yuan, Yue

    2013-01-01

    Based on the bifurcation and stability theory of dynamical systems, the symmetric/asymmetric bifurcation behaviours and chaotic motions of a railway bogie system under a complex nonlinear wheel–rail contact relation are investigated in detail by the ‘resultant bifurcation diagram’ method with slo...

  4. Codimension 2 Bifurcations of Iterated Maps

    NARCIS (Netherlands)

    Meijer, H.G.E.

    2006-01-01

    This thesis investigates some properties of discrete-time dynamical systems, generated by iterated maps. In particular we study local bifurcations where two parameters are essential to describe the dynamical properties of the system near a fixed point or a cycle. There are 11 such cases. Knowledge

  5. Percutaneous coronary intervention for coronary bifurcation disease

    DEFF Research Database (Denmark)

    Lassen, Jens Flensted; Holm, Niels Ramsing; Banning, Adrian

    2016-01-01

    of combining the opinions of interventional cardiologists with the opinions of a large variety of other scientists on bifurcation management. The present 11th EBC consensus document represents the summary of the up-to-date EBC consensus and recommendations. It points to the fact that there is a multitude...

  6. Bifurcation of self-folded polygonal bilayers

    Science.gov (United States)

    Abdullah, Arif M.; Braun, Paul V.; Hsia, K. Jimmy

    2017-09-01

    Motivated by the self-assembly of natural systems, researchers have investigated the stimulus-responsive curving of thin-shell structures, which is also known as self-folding. Self-folding strategies not only offer possibilities to realize complicated shapes but also promise actuation at small length scales. Biaxial mismatch strain driven self-folding bilayers demonstrate bifurcation of equilibrium shapes (from quasi-axisymmetric doubly curved to approximately singly curved) during their stimulus-responsive morphing behavior. Being a structurally instable, bifurcation could be used to tune the self-folding behavior, and hence, a detailed understanding of this phenomenon is appealing from both fundamental and practical perspectives. In this work, we investigated the bifurcation behavior of self-folding bilayer polygons. For the mechanistic understanding, we developed finite element models of planar bilayers (consisting of a stimulus-responsive and a passive layer of material) that transform into 3D curved configurations. Our experiments with cross-linked Polydimethylsiloxane samples that change shapes in organic solvents confirmed our model predictions. Finally, we explored a design scheme to generate gripper-like architectures by avoiding the bifurcation of stimulus-responsive bilayers. Our research contributes to the broad field of self-assembly as the findings could motivate functional devices across multiple disciplines such as robotics, artificial muscles, therapeutic cargos, and reconfigurable biomedical devices.

  7. Climate bifurcation during the last deglaciation?

    NARCIS (Netherlands)

    Lenton, T.M.; Livina, V.N.; Dakos, V.; Scheffer, M.

    2012-01-01

    There were two abrupt warming events during the last deglaciation, at the start of the Bolling-Allerod and at the end of the Younger Dryas, but their underlying dynamics are unclear. Some abrupt climate changes may involve gradual forcing past a bifurcation point, in which a prevailing climate state

  8. Dynamics and geometry near resonant bifurcations

    NARCIS (Netherlands)

    Broer, Hendrik; Holtman, Sijbo J.; Vegter, Gert; Vitolo, Renato

    This paper provides an overview of the universal study of families of dynamical systems undergoing a Hopf-NeAmarck-Sacker bifurcation as developed in [1-4]. The focus is on the local resonance set, i.e., regions in parameter space for which periodic dynamics occurs. A classification of the

  9. Evaluation of virtual monoenergetic imaging algorithms for dual-energy carotid and intracerebral CT angiography: Effects on image quality, artefacts and diagnostic performance for the detection of stenosis.

    Science.gov (United States)

    Leithner, Doris; Mahmoudi, Scherwin; Wichmann, Julian L; Martin, Simon S; Lenga, Lukas; Albrecht, Moritz H; Booz, Christian; Arendt, Christophe T; Beeres, Martin; D'Angelo, Tommaso; Bodelle, Boris; Vogl, Thomas J; Scholtz, Jan-Erik

    2018-02-01

    To investigate the impact of traditional (VMI) and noise-optimized virtual monoenergetic imaging (VMI+) algorithms on quantitative and qualitative image quality, and the assessment of stenosis in carotid and intracranial dual-energy CTA (DE-CTA). DE-CTA studies of 40 patients performed on a third-generation 192-slice dual-source CT scanner were included in this retrospective study. 120-kVp image-equivalent linearly-blended, VMI and VMI+ series were reconstructed. Quantitative analysis included evaluation of contrast-to-noise ratios (CNR) of the aorta, common carotid artery, internal carotid artery, middle cerebral artery, and basilar artery. VMI and VMI+ with highest CNR, and linearly-blended series were rated qualitatively. Three radiologists assessed artefacts and suitability for evaluation at shoulder height, carotid bifurcation, siphon, and intracranial using 5-point Likert scales. Detection and grading of stenosis were performed at carotid bifurcation and siphon. Highest CNR values were observed for 40-keV VMI+ compared to 65-keV VMI and linearly-blended images (P evaluation at shoulder and bifurcation height. Suitability was significantly higher in VMI+ and VMI compared to linearly-blended images for intracranial and ICA assessment (P performance. 40-keV VMI+ showed improved quantitative image quality compared to 65-keV VMI and linearly-blended series in supraaortic DE-CTA. VMI and VMI+ provided increased suitability for carotid and intracranial artery evaluation with excellent assessment of stenosis, but did not translate into increased diagnostic performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Climate bifurcation during the last deglaciation

    Science.gov (United States)

    Lenton, T. M.; Livina, V. N.; Dakos, V.; Scheffer, M.

    2012-01-01

    The last deglaciation was characterised by two abrupt warming events, at the start of the Bølling-Allerød and at the end of the Younger Dryas, but their underlying causes are unclear. Some abrupt climate changes may involve gradual forcing past a bifurcation point, in which a prevailing climate state loses its stability and the climate tips into an alternative state, providing an early warning signal in the form of slowing responses to perturbations. However, the abrupt Dansgaard-Oeschger (DO) events during the last ice age were probably triggered by stochastic fluctuations without bifurcation or early warning, and whether the onset of the Bølling-Allerød (DO event 1) was preceded by slowing down or not is debated. Here we show that the interval from the Last Glacial Maximum to the end of the Younger Dryas, as recorded in three Greenland ice cores with two different climate proxies, was accompanied by a robust slowing down in climate dynamics and an increase in climate variability, consistent with approaching bifurcation. Prior to the Bølling warming there was a robust increase in climate variability but no consistent slowing down signal, suggesting this abrupt change was probably triggered by a stochastic fluctuation. The Bølling warming marked a distinct destabilisation of the climate system, which excited an internal mode of variability in Atlantic meridional overturning circulation strength, causing multi-centennial climate fluctuations. There is some evidence for slowing down in the transition to and during the Younger Dryas. We infer that a bifurcation point was finally approached at the end of the Younger Dryas, in which the cold climate state, with weak Atlantic overturning circulation, lost its stability, and the climate tipped irreversibly into a warm interglacial state. The lack of a large triggering perturbation at the end of the Younger Dryas, and the fact that subsequent meltwater perturbations did not cause sustained cooling, support the

  11. A 22-year Northern Irish experience of carotid body tumours.

    Science.gov (United States)

    O'Neill, Stephen; O'Donnell, Mark; Harkin, Denis; Loughrey, Maurice; Lee, Bernard; Blair, Paul

    2011-09-01

    Carotid body tumours (CBTs) are rare vascular neoplasms originating in paraganglionic cells of the carotid bifurcation. The aim of this study was to review all patients diagnosed with CBTs in Northern Ireland. A retrospective review was performed of all patients who had CBTs treated at our institutions between 1987 and 2009. Patient demographics, clinical symptomatology, investigative modality, therapeutic intervention, pathological analysis and long-term outcomes were assessed. Twenty-nine patients were identified with 33 CBTs and three glomus intravagale tumours (GITs). Six patients had bilateral CBTs (21%), one of whom had a synchronous GIT. Twenty-six patients underwent a total of 30 operative procedures for the resection of 28 CBTs and 3 GITs. Conventional operative treatment included subadventitial tumour excision. A vascular shunt facilitated arterial reconstruction following the removal of seven (23%) tumours and on six of these occasions (19%) continuity was restored with an interposition vein graft. For access the external carotid artery was ligated during the removal of four tumours (13%). Two tumours were considered malignant. No peri-operative mortalities were recorded. Immediate complications included peri-operative stroke secondary to an occluded vein graft (n=1), requirement of tracheostomy (n=2), emergency haematoma drainage (n=2) and transient cranial nerve damage (n=8). Late complications included pseudoaneurysm of vein graft with subsequent stoke (n=1), permanent cranial nerve damage (n=9), Horner's syndrome (n=1) and an asymptomatic vein graft occlusion (n=1). One patient had tumour recurrence two years post-operatively and died due to pulmonary metastases. Two other patients died of unrelated causes. All other patients remain well with no evidence of tumour recurrence at mean followup of 1801 days (range 159-9208 days). Our long-term experience is comparable with other reported case series where surgical intervention conferred a long

  12. Electrical carotid sinus stimulation in treatment resistant arterial hypertension.

    Science.gov (United States)

    Jordan, Jens; Heusser, Karsten; Brinkmann, Julia; Tank, Jens

    2012-12-24

    Treatment resistant arterial hypertension is commonly defined as blood pressure that remains above goal in spite of the concurrent use of three antihypertensive agents of different classes. The sympathetic nervous system promotes arterial hypertension and cardiovascular as well as renal damage, thus, providing a logical treatment target in these patients. Recent physiological studies suggest that baroreflex mechanisms contribute to long-term control of sympathetic activity and blood pressure providing an impetus for the development of electrical carotid sinus stimulators. The concept behind electrical stimulation of baroreceptors or baroreflex afferent nerves is that the stimulus is sensed by the brain as blood pressure increase. Then, baroreflex efferent structures are adjusted to counteract the perceived blood pressure increase. Electrical stimulators directly activating afferent baroreflex nerves were developed years earlier but failed for technical reasons. Recently, a novel implantable device was developed that produces an electrical field stimulation of the carotid sinus wall. Carefully conducted experiments in dogs provided important insight in mechanisms mediating the depressor response to electrical carotid sinus stimulation. Moreover, these studies showed that the treatment success may depend on the underlying pathophysiology of the hypertension. Clinical studies suggest that electrical carotid sinus stimulation attenuates sympathetic activation of vasculature, heart, and kidney while augmenting cardiac vagal regulation, thus lowering blood pressure. Yet, not all patients respond to treatment. Additional clinical trials are required. Patients equipped with an electrical carotid sinus stimulator provide a unique opportunity gaining insight in human baroreflex physiology. Copyright © 2012. Published by Elsevier B.V.

  13. Intraoperative Completion Studies, Local Anesthesia, and Antiplatelet Medication Are Associated With Lower Risk in Carotid Endarterectomy.

    Science.gov (United States)

    Knappich, Christoph; Kuehnl, Andreas; Tsantilas, Pavlos; Schmid, Sofie; Breitkreuz, Thorben; Kallmayer, Michael; Zimmermann, Alexander; Eckstein, Hans-Henning

    2017-04-01

    In Germany, all surgical and endovascular procedures on the carotid bifurcation must be documented in a statutory nationwide quality assurance database. We aimed to analyze the association between procedural and perioperative variables and in-hospital stroke or death rates after carotid endarterectomy. Between 2009 and 2014, overall 142 074 elective carotid endarterectomy procedures for asymptomatic or symptomatic carotid artery stenosis were documented in the database. The primary outcome of this secondary data analysis was in-hospital stroke or death. Major stroke or death, stroke, and death, each until discharge were secondary outcomes. Adjusted relative risks (RRs) were assessed by multivariable multilevel regression analyses. The primary outcome occurred in 1.8% of patients, with a rate of 1.4% in asymptomatic and 2.5% in symptomatic patients, respectively. In the multivariable analysis, lower risks of stroke or death were independently associated with local anesthesia (versus general anesthesia: RR, 0.85; 95% confidence interval [CI], 0.75-0.95), carotid endarterectomy with patch plasty compared with primary closure (RR, 0.71; 95% CI, 0.52-0.97), intraoperative completion studies by duplex ultrasound (RR, 0.74; 95% CI, 0.63-0.88) or angiography (RR, 0.80; 95% CI, 0.71-0.90), and perioperative antiplatelet medication (RR, 0.83; 95% CI, 0.71-0.97). No shunting and a short cross-clamp time were also associated with lower risks; however, these are suspected to be confounded. Local anesthesia, patch plasty compared with primary closure, intraoperative completion studies by duplex ultrasound or angiography, and perioperative antiplatelet medication were independently associated with lower in-hospital stroke or death rates after carotid endarterectomy. © 2017 American Heart Association, Inc.

  14. Colour Doppler evaluation of extracranial carotid artery in patients presenting with features of cerebrovascular disease: A clinical and radiological correlation

    Directory of Open Access Journals (Sweden)

    Sanjeev Sehrawat

    2012-01-01

    atheromatous plaque was found to be carotid bifurcation (33.3%. Significant stenosis, i.e., >50% was found in 12 (60% of the cases. Peak systolic velocity ratio showed significant stenosis in 12 (60% of symptomatic cases and in 4 (20% of asymptomatic controls. Plaque characteristics showed 9 hyperechogenic, 8 calcific, 4 low echogenic and 5 moderate or heterogeneous plaques. Conclusion: The role of carotid Doppler in detecting the site and morphology of atherosclerotic plaque with quantifying the amount of stenosis is very well-justified. In addition carotid Doppler can also be used to assess the prognosis in potential symptomatic and asymptomatic patients with one or the other risk factors for cerebrovascular disease.

  15. Bifurcation Behavior Analysis in a Predator-Prey Model

    Directory of Open Access Journals (Sweden)

    Nan Wang

    2016-01-01

    Full Text Available A predator-prey model is studied mathematically and numerically. The aim is to explore how some key factors influence dynamic evolutionary mechanism of steady conversion and bifurcation behavior in predator-prey model. The theoretical works have been pursuing the investigation of the existence and stability of the equilibria, as well as the occurrence of bifurcation behaviors (transcritical bifurcation, saddle-node bifurcation, and Hopf bifurcation, which can deduce a standard parameter controlled relationship and in turn provide a theoretical basis for the numerical simulation. Numerical analysis ensures reliability of the theoretical results and illustrates that three stable equilibria will arise simultaneously in the model. It testifies the existence of Bogdanov-Takens bifurcation, too. It should also be stressed that the dynamic evolutionary mechanism of steady conversion and bifurcation behavior mainly depend on a specific key parameter. In a word, all these results are expected to be of use in the study of the dynamic complexity of ecosystems.

  16. Stochastic bifurcation in a model of love with colored noise

    Science.gov (United States)

    Yue, Xiaokui; Dai, Honghua; Yuan, Jianping

    2015-07-01

    In this paper, we wish to examine the stochastic bifurcation induced by multiplicative Gaussian colored noise in a dynamical model of love where the random factor is used to describe the complexity and unpredictability of psychological systems. First, the dynamics in deterministic love-triangle model are considered briefly including equilibrium points and their stability, chaotic behaviors and chaotic attractors. Then, the influences of Gaussian colored noise with different parameters are explored such as the phase plots, top Lyapunov exponents, stationary probability density function (PDF) and stochastic bifurcation. The stochastic P-bifurcation through a qualitative change of the stationary PDF will be observed and bifurcation diagram on parameter plane of correlation time and noise intensity is presented to find the bifurcation behaviors in detail. Finally, the top Lyapunov exponent is computed to determine the D-bifurcation when the noise intensity achieves to a critical value. By comparison, we find there is no connection between two kinds of stochastic bifurcation.

  17. Cardiovascular magnetic resonance in carotid atherosclerotic disease

    Directory of Open Access Journals (Sweden)

    Chen Huijun

    2009-12-01

    Full Text Available Abstract Atherosclerosis is a chronic, progressive, inflammatory disease affecting many vascular beds. Disease progression leads to acute cardiovascular events such as myocardial infarction, stroke and death. The diseased carotid alone is responsible for one third of the 700,000 new or recurrent strokes occurring yearly in the United States. Imaging plays an important role in the management of atherosclerosis, and cardiovascular magnetic resonance (CMR of the carotid vessel wall is one promising modality in the evaluation of patients with carotid atherosclerotic disease. Advances in carotid vessel wall CMR allow comprehensive assessment of morphology inside the wall, contributing substantial disease-specific information beyond luminal stenosis. Although carotid vessel wall CMR has not been widely used to screen for carotid atherosclerotic disease, many trials support its potential for this indication. This review summarizes the current state of knowledge regarding carotid vessel wall CMR and its potential clinical application for management of carotid atherosclerotic disease.

  18. Carotid plaque thickness and carotid plaque burden predict future cardiovascular events in asymptomatic adult Americans

    DEFF Research Database (Denmark)

    Sillesen, Henrik; Sartori, Samantha; Sandholt, Benjamin

    2018-01-01

    Introduction: Prediction of cardiovascular events improves using imaging, i.e. coronary calcium score and ultrasound assessment of carotid plaque. This study analysed the predictive value of two ultrasound measures of carotid plaque size: carotid plaque thickness and carotid and intima......-media thickness (IMT). Methods and results: A total of 6102 asymptomatic persons underwent assessment of conventional risk factors and imaging by carotid ultrasound. Carotid plaque burden (cPB) and maximum carotid plaque thickness (cPTmax) were measured from 'cross-sectional sweep' video acquisition...

  19. Estimation of an image derived input function with MR-defined carotid arteries in FDG-PET human studies using a novel partial volume correction method.

    Science.gov (United States)

    Sari, Hasan; Erlandsson, Kjell; Law, Ian; Larsson, Henrik Bw; Ourselin, Sebastien; Arridge, Simon; Atkinson, David; Hutton, Brian F

    2017-04-01

    Kinetic analysis of 18 F-fluorodeoxyglucose positron emission tomography data requires an accurate knowledge the arterial input function. The gold standard method to measure the arterial input function requires collection of arterial blood samples and is an invasive method. Measuring an image derived input function is a non-invasive alternative but is challenging due to partial volume effects caused by the limited spatial resolution of the positron emission tomography scanners. In this work, a practical image derived input function extraction method is presented, which only requires segmentation of the carotid arteries from MR images. The simulation study results showed that at least 92% of the true intensity could be recovered after the partial volume correction. Results from 19 subjects showed that the mean cerebral metabolic rate of glucose calculated using arterial samples and partial volume corrected image derived input function were 26.9 and 25.4 mg/min/100 g, respectively, for the grey matter and 7.2 and 6.7 mg/min/100 g for the white matter. No significant difference in the estimated cerebral metabolic rate of glucose values was observed between arterial samples and corrected image derived input function (p > 0.12 for grey matter and white matter). Hence, the presented image derived input function extraction method can be a practical alternative to noninvasively analyze dynamic 18 F-fluorodeoxyglucose data without the need for blood sampling.

  20. Partitioning of red blood cell aggregates in bifurcating microscale flows

    Science.gov (United States)

    Kaliviotis, E.; Sherwood, J. M.; Balabani, S.

    2017-03-01

    Microvascular flows are often considered to be free of red blood cell aggregates, however, recent studies have demonstrated that aggregates are present throughout the microvasculature, affecting cell distribution and blood perfusion. This work reports on the spatial distribution of red blood cell aggregates in a T-shaped bifurcation on the scale of a large microvessel. Non-aggregating and aggregating human red blood cell suspensions were studied for a range of flow splits in the daughter branches of the bifurcation. Aggregate sizes were determined using image processing. The mean aggregate size was marginally increased in the daughter branches for a range of flow rates, mainly due to the lower shear conditions and the close cell and aggregate proximity therein. A counterintuitive decrease in the mean aggregate size was apparent in the lower flow rate branches. This was attributed to the existence of regions depleted by aggregates of certain sizes in the parent branch, and to the change in the exact flow split location in the T-junction with flow ratio. The findings of the present investigation may have significant implications for microvascular flows and may help explain why the effects of physiological RBC aggregation are not deleterious in terms of in vivo vascular resistance.

  1. Asymptomatic carotid arterial stenosis - population based screening

    NARCIS (Netherlands)

    2010-01-01

    Screening for asymptomatic carotid artery stenosis in the general population is discussed in many countries because of the benefits of carotid endarterectomy in the three trials. Many factors influence the cost-effectiveness of screening. These factors are the prevalence of carotid stenosis, the

  2. Carotid artery stenting : a 2009 update

    NARCIS (Netherlands)

    Zeebregts, Clark J.; Meerwaldt, Robbert; Geelkerken, Robert H.

    2009-01-01

    Purpose of review Carotid endarterectomy (CEA) is is still considered the gold standard in the treatment of patients with significant carotid stenosis and has proven its value over the past decades. Endovascular techniques have evolved, and carotid artery stenting (CAS) is challenging CEA to become

  3. The Interaction Between Carotid Baroreceptor and Chemoreceptor ...

    African Journals Online (AJOL)

    Hypertension and hypoxia often occur together in the clinical setting implying that the carotid baroreceptor and carotid chemoreceptors are affected simultaneously. This work was designed to study the effects of increased reflex sympathetic activity following carotid baroreceptor and chemoreceptor stimulation on reflex ...

  4. Cerebral hyperperfusion following carotid endarterectomy

    DEFF Research Database (Denmark)

    Schroeder, T; Sillesen, H; Sørensen, O

    1987-01-01

    Serial measurements of cerebral blood flow (CBF) were performed in 56 patients before and one to four times after uncomplicated carotid endarterectomy. The findings were related to the ratio between internal carotid artery (ICA) and common carotid artery (CCA) mean pressures. Within the 1st...... postoperative day CBF increased by a median of 37% in the ipsilateral and 33% in the contralateral hemisphere. Later recordings showed a gradual return of CBF toward the preoperative level. Sixteen patients with an ICA/CCA pressure ratio below 0.7 showed a significantly more pronounced and longer-lasting flow......, occurred in the low pressure ratio group, while the hemispheric asymmetry on average was unchanged in the high pressure ratio group. This relative hyperemia was most pronounced 2 to 4 days following reconstruction. The marked hyperemia, absolute as well as relative, in patients with a low ICA/CCA pressure...

  5. Carotid endarterectomy with regional anesthesia.

    Science.gov (United States)

    Harbaugh, R E; Pikus, H J

    2001-09-01

    The senior author (REH) has changed his technique for performing carotid endarterectomy from the use of general anesthesia to the use of cervical block anesthesia. Because a randomized study was not performed, it is difficult to separate effects of increased surgical experience from those caused by a change in anesthetic regimen. Nonetheless, there has been a substantial decrease in complications, length of hospital stay, and costs concomitant with the change to regional anesthesia; we think there is a causal relationship. The use of cervical block anesthesia has practically eliminated the non-stroke-related complications associated with carotid endarterectomy in our practice. The technique for performing carotid endarterectomy under cervical block anesthesia is described in detail.

  6. Standard duplex criteria overestimate the degree of stenosis after eversion carotid endarterectomy.

    Science.gov (United States)

    Benzing, Travis; Wilhoit, Cameron; Wright, Sharee; McCann, P Aaron; Lessner, Susan; Brothers, Thomas E

    2015-06-01

    The eversion technique for carotid endarterectomy (eCEA) offers an alternative to longitudinal arteriotomy and patch closure (pCEA) for open carotid revascularization. In some reports, eCEA has been associated with a higher rate of >50% restenosis of the internal carotid when it is defined as peak systolic velocity (PSV) >125 cm/s by duplex imaging. Because the conformation of the carotid bifurcation may differ after eCEA compared with native carotid arteries, it was hypothesized that standard duplex criteria might not accurately reflect the presence of restenosis after eCEA. In a case-control study, the outcomes of all patients undergoing carotid endarterectomy by one surgeon during the last 10 years were analyzed retrospectively, with a primary end point of PSV >125 cm/s. Duplex flow velocities were compared with luminal diameter measurements for any carotid computed tomography arteriography or magnetic resonance angiography study obtained within 2 months of duplex imaging, with the degree of stenosis calculated by the methodology used in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST) as well as cross-sectional area (CSA) reduction. Simulations were generated and analyzed by computational model simulations of the eCEA and pCEA arteries. Eversion and longitudinal arteriotomy with patch techniques were used in 118 and 177 carotid arteries, respectively. Duplex follow-up was available in 90 eCEA arteries at a median of 16 (range, 2-136) months and in 150 pCEA arteries at a median of 41 (range, 3-115) months postoperatively. PSV >125 cm/s was present at some time during follow-up in 31% of eCEA and pCEA carotid arteries, each, and in the most recent duplex examination in 7% after eCEA and 21% after pCEA (P = .003), with no eCEA and two pCEA arteries occluding completely during follow-up (P = .29). In 19 carotid arteries with PSV >125 cm/s after angle correction (median, 160 cm/s; interquartile range

  7. Bifurcations at the dawn of Modern Science

    Science.gov (United States)

    Coullet, Pierre

    2012-11-01

    In this article we review two classical bifurcation problems: the instability of an axisymmetric floating body studied by Archimedes, 2300 years ago and the multiplicity of images observed in curved mirrors, a problem which has been solved by Alhazen in the 11th century. We will first introduce these problems in trying to keep some of the flavor of the original analysis and then, we will show how they can be reduced to a question of extremal distances studied by Apollonius.

  8. Perturbed period-doubling bifurcation. I. Theory

    DEFF Research Database (Denmark)

    Svensmark, Henrik; Samuelsen, Mogens Rugholm

    1990-01-01

    -defined way that is a function of the amplitude and the frequency of the signal. New scaling laws between the amplitude of the signal and the detuning δ are found; these scaling laws apply to a variety of quantities, e.g., to the shift of the bifurcation point. It is also found that the stability...... of a microwave-driven Josephson junction confirm the theory. Results should be of interest in parametric-amplification studies....

  9. Sex differences in intracranial arterial bifurcations

    DEFF Research Database (Denmark)

    Lindekleiv, Haakon M; Valen-Sendstad, Kristian; Morgan, Michael K

    2010-01-01

    Subarachnoid hemorrhage (SAH) is a serious condition, occurring more frequently in females than in males. SAH is mainly caused by rupture of an intracranial aneurysm, which is formed by localized dilation of the intracranial arterial vessel wall, usually at the apex of the arterial bifurcation. T....... The female preponderance is usually explained by systemic factors (hormonal influences and intrinsic wall weakness); however, the uneven sex distribution of intracranial aneurysms suggests a possible physiologic factor-a local sex difference in the intracranial arteries....

  10. The prognostic role of carotid plaque ultrasonography in cardiac damage after carotid endarterectomy: carotid plaque and cardiac risk.

    Science.gov (United States)

    Galyfos, George; Toutouzas, Konstantinos P; Benetos, George; Konstadoulakis, Manousos; Theodorou, Dimitrios; Katsaragakis, Stilianos; Stefanadis, Christodoulos; Zografos, Georgios; Filis, Konstantinos

    2016-10-01

    This study evaluates the correlation of ultrasound determined carotid plaque morphology with coronary risk and cardiac damage after carotid endarterectomy. Fifty patients (in a series of 162) scheduled for carotid endarterectomy had the indication for coronary CT-angiography preoperatively and were included in this study. Patients were classified according to ultrasonographic characteristics of carotid plaque. The Duke Criteria were used to assess the degree of coronary risk (low, medium and high risk). Cardiac damage after carotid endarterectomy was evaluated based on symptoms, cardiac Troponin I measurement and electrocardiographic findings. There were no deaths, strokes or symptomatic myocardial infarctions postoperatively (30-day results). Ten patients (20%) showed asymptomatic cardiac damage postoperatively. Cardiac damage after surgery did not show any difference between the three cardiac risk groups. Echogenic and specifically Type IV carotid artery plaques (Gray-Weale Criteria) were associated with high cardiac risk preoperatively and with postoperative cardiac damage. The degree of carotid artery stenosis, and echolucent carotid plaques were not associated with postoperative cardiac damage. Asymptomatic postoperative cardiac damage occurs often after carotid endarterectomy and presents independently from coronary risk. Carotid plaques of higher echogenicity are associated with severity of coronary artery disease and cardiac damage after carotid endarterectomy.

  11. Carotid cavernous fistula after elective carotid endarterectomy: Case report

    Directory of Open Access Journals (Sweden)

    Andres Asser

    2014-12-01

    This is a case to illustrate a rare complication of carotid artery surgery. The patient had atherosclerotic vessel damage of ICA visible on earlier CT scans. This combined with abrupt increase of transmural pressure due to the revascularization procedure could possibly lead to arterial wall rupture and fistula formation.

  12. Results of the ANSWER Trial Using the PulseRider for the Treatment of Broad-Necked, Bifurcation Aneurysms.

    Science.gov (United States)

    Spiotta, Alejandro M; Derdeyn, Colin P; Tateshima, Satoshi; Mocco, Jay; Crowley, R Webster; Liu, Kenneth C; Jensen, Lee; Ebersole, Koji; Reeves, Alan; Lopes, Demetrius K; Hanel, Ricardo A; Sauvageau, Eric; Duckwiler, Gary; Siddiqui, Adnan; Levy, Elad; Puri, Ajit; Pride, Lee; Novakovic, Roberta; Chaudry, M Imran; Turner, Raymond D; Turk, Aquilla S

    2017-07-01

    The safety and probable benefit of the PulseRider (Pulsar Vascular, Los Gatos, California) for the treatment of broad-necked, bifurcation aneurysms was studied in the context of the prospective, nonrandomized, single arm clinical trial-the Adjunctive Neurovascular Support of Wide-neck aneurysm Embolization and Reconstruction (ANSWER) Trial. To present the results of the United States cases employing the PulseRider device as part of the ANSWER clinical trial. Aneurysms treated with the PulseRider device among sites enrolling in the ANSWER trial were prospectively studied and the results are summarized. Aneurysms arising at either the carotid terminus or basilar apex that were relatively broad necked were considered candidates for inclusion into the ANSWER study. Thirty-four patients were enrolled (29 female and 5 male) with a mean age of 60.9 years (27 basilar apex and 7 carotid terminus). Mean aneurysm height ranged from 2.4 to 15.9 mm with a mean neck size of 5.2 mm (range 2.3-11.6 mm). In all patients, the device was delivered and deployed. Immediate Raymond I or II occlusion was achieved in 82.4% and progressed to 87.9% at 6-month follow-up. A modified Rankin Score of 2 or less was seen in 94% of patients at 6 months. The results from the ANSWER trial demonstrate that the PulseRider device is safe and offers probable benefit as for the treatment of bifurcation aneurysms arising at the basilar apex or carotid terminus. As such, it represents a useful addition to the armamentarium of the neuroendovascular specialist.

  13. Stenting of bifurcation lesions: a rational approach.

    Science.gov (United States)

    Lefèvre, T; Louvard, Y; Morice, M C; Loubeyre, C; Piéchaud, J F; Dumas, P

    2001-12-01

    The occurrence of stenosis in or next to coronary bifurcations is relatively frequent and generally underestimated. In our experience, such lesions account for 15%-18% of all percutaneous coronary intervention > (PCI). The main reasons for this are (1) the coronary arteries are like the branches of a tree with many ramifications and (2) because of axial plaque redistribution, especially after stent implantation, PCI of lesions located next to a coronary bifurcation almost inevitably cause plaque shifting in the side branches. PCI treatment of coronary bifurcation lesions remains challenging. Balloon dilatation treatment used to be associated with less than satisfactory immediate results, a high complication rate, and an unacceptable restenosis rate. The kissing balloon technique resulted in improved, though suboptimal, outcomes. Several approaches were then suggested, like rotative or directional atherectomy, but these techniques did not translate into significantly enhanced results. With the advent of second generation stents, in 1996, the authors decided to set up an observational study on coronary bifurcation stenting combined with a bench test of the various stents available. Over the last 5 years, techniques, strategies, and stent design have improved. As a result, the authors have been able to define a rational approach to coronary bifurcation stenting. This bench study analyzed the behavior of stents and allowed stents to be discarded that are not compatible with the treatment of coronary bifurcations. Most importantly, this study revealed that stent deformation due to the opening of a strut is a constant phenomenon that must be corrected by kissing balloon inflation. Moreover, it was observed that the opening of a stent strut into a side branch could permit the stenting, at least partly, of the side branch ostium. This resulted in the provocative concept of "stenting both branches with a single stent." Therefore, a simple approach is currently implemented

  14. Carotid revascularization and medical management for asymptomatic carotid stenosis: Protocol of the CREST-2 clinical trials.

    Science.gov (United States)

    Howard, Virginia J; Meschia, James F; Lal, Brajesh K; Turan, Tanya N; Roubin, Gary S; Brown, Robert D; Voeks, Jenifer H; Barrett, Kevin M; Demaerschalk, Bart M; Huston, John; Lazar, Ronald M; Moore, Wesley S; Wadley, Virginia G; Chaturvedi, Seemant; Moy, Claudia S; Chimowitz, Marc; Howard, George; Brott, Thomas G

    2017-10-01

    Rationale Trials conducted decades ago demonstrated that carotid endarterectomy by skilled surgeons reduced stroke risk in asymptomatic patients. Developments in carotid stenting and improvements in medical prevention of stroke caused by atherothrombotic disease challenge understanding of the benefits of revascularization. Aim Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial (CREST-2) will test whether carotid endarterectomy or carotid stenting plus contemporary intensive medical therapy is superior to intensive medical therapy alone in the primary prevention of stroke in patients with high-grade asymptomatic carotid stenosis. Methods and design CREST-2 is two multicenter randomized trials of revascularization plus intensive medical therapy versus intensive medical therapy alone. One trial randomizes patients to carotid endarterectomy plus intensive medical therapy versus intensive medical therapy alone; the other, to carotid stenting plus intensive medical therapy versus intensive medical therapy alone. The risk factor targets of centrally directed intensive medical therapy are LDL cholesterol medical therapy alone arm is 4.8% higher or 2.8% lower than an anticipated 3.6% rate in the revascularization arm. Discussion Management of asymptomatic carotid stenosis requires contemporary randomized trials to address whether carotid endarterectomy or carotid stenting plus intensive medical therapy is superior in preventing stroke beyond intensive medical therapy alone. Whether carotid endarterectomy or carotid stenting has favorable effects on cognition will also be tested. Trial registration United States National Institutes of Health Clinicaltrials.gov NCT02089217.

  15. Carotid and femoral ultrasound morphology screening and cardiovascular events in low risk subjects: a 10-year follow-up study (the CAFES-CAVE study(1)).

    Science.gov (United States)

    Belcaro, G; Nicolaides, A N; Ramaswami, G; Cesarone, M R; De Sanctis, M; Incandela, L; Ferrari, P; Geroulakos, G; Barsotti, A; Griffin, M; Dhanjil, S; Sabetai, M; Bucci, M; Martines, G

    2001-06-01

    Subclinical arteriosclerotic lesions at the carotid and femoral bifurcations may be related to the occurrence of future cardiovascular events and of occult arteriosclerotic coronary disease. B-mode ultrasound of carotid and femoral arteriosclerotic bifurcation lesions may provide a simple screening method to select asymptomatic subjects at risk of future events. 13221 low-risk, healthy, asymptomatic individuals were included in a 10-year, prospective, follow-up based on carotid and femoral bifurcation morphology defined by B-mode ultrasound. Four classes were considered at inclusion (I: normal wall, II: wall thickening, III: non-stenosing plaques, IV: stenosing plaques). When 10000 subjects (75.6% of included subjects; 6055 males, 3945 females) completed the 10-year follow-up the study was concluded. At 10 years there were 10 events (out of 7989 subjects) in class I and 81 events in II (930 subjects; incidence=8.6%); 239 events were observed in class III (611 subjects; 39.28%) and 381 events (470 subjects; 81.06%) in IV; 61 deaths occurred in classes III+IV (1081 subjects) producing a death rate within these two classes of 5.5% (51 out of 61=81.5% in class IV). The increased event rates in classes III and IV were significant (log rank; P<0.02) in comparison with I and II. Carotid and femoral morphology identified 2011 subjects (20.1% of the population) in classes II,III,IV including 98.6% of cardiovascular events and deaths in the following 10 years. A higher (P<0.05) rate of progression in classes III and IV in comparison with I and II was also observed. The ultrasound carotid and femoral classification was useful in selecting subjects at very low risk of cardiovascular events (class I), those at limited risk (class II) and a group at moderate risk (class III). A subpopulation at high risk of cardiovascular events (IV) was identified.

  16. AnAtomicAl vAriAtions of the cArotid Arteries in Adult KenyAns

    African Journals Online (AJOL)

    2008-05-05

    May 5, 2008 ... Adult KenyAns d. anangwE, H. saidi, J. ogEng'o and K.o. awori. ABstrAct. Objective: to describe the topography and anatomical variations of the carotid arteries among. Kenyans. Design: A descriptive cross-sectional study. Setting: department of human Anatomy, university of nairobi. Subjects: eighty carotid ...

  17. Bifurcation and Firing Patterns of the Pancreatic β-Cell

    Science.gov (United States)

    Wang, Jing; Liu, Shenquan; Liu, Xuanliang; Zeng, Yanjun

    Using a model of individual isolated pancreatic β-cells, we investigated bifurcation diagrams of interspike intervals (ISIs) and largest Lyapunov exponents (LLE), which clearly demonstrated a wide range of transitions between different firing patterns. The numerical simulation results revealed the effect of different time constants and ion channels on the neuronal discharge rhythm. Furthermore, an individual cell exhibited tonic spiking, square-wave bursting, and tapered bursting. Additionally, several bifurcation phenomena can be observed in this paper, such as period-doubling, period-adding, inverse period-doubling and inverse period-adding scenarios. In addition, we researched the mechanisms underlying two kinds of bursting (tapered and square-wave bursting) by use of fast-slow dynamics analysis. Finally, we analyzed the codimension-two bifurcation of the fast subsystem and studied cusp bifurcation, generalized Hopf (or Bautin) bifurcation and Bogdanov-Takens bifurcation.

  18. Understanding a Period-Doubling Bifurcation in Cardiac Cells

    Science.gov (United States)

    Berger, Carolyn; Zhao, Xiaopeng; Schaeffer, David; Idriss, Salim; Gauthier, Daniel

    2008-03-01

    Bifurcations in the electrical response of cardiac tissue can destabilize spatio-temporal waves of electrochemical activity in the heart, leading to tachycardia or even fibrillation. Therefore, it is important to classify these bifurcations so that we can understand the mechanisms that cause instabilities in cardiac tissue. We have determined that the period-doubling bifurcation in paced myocardium is of the unfolded border-collision type. To understand how this new type of bifurcation manifest itself in cardiac tissue, we have also studied the role of calcium in inducing the bifurcation. We will discuss the nature of the unfolded border-collision bifurcation and present our results of dual voltage and calcium measurements in a frog ventricle preparation.

  19. Global Bifurcation of a Novel Computer Virus Propagation Model

    Directory of Open Access Journals (Sweden)

    Jianguo Ren

    2014-01-01

    Full Text Available In a recent paper by J. Ren et al. (2012, a novel computer virus propagation model under the effect of the antivirus ability in a real network is established. The analysis there only partially uncovers the dynamics behaviors of virus spread over the network in the case where around bifurcation is local. In the present paper, by mathematical analysis, it is further shown that, under appropriate parameter values, the model may undergo a global B-T bifurcation, and the curves of saddle-node bifurcation, Hopf bifurcation, and homoclinic bifurcation are obtained to illustrate the qualitative behaviors of virus propagation. On this basis, a collection of policies is recommended to prohibit the virus prevalence. To our knowledge, this is the first time the global bifurcation has been explored for the computer virus propagation. Theoretical results and corresponding suggestions may help us suppress or eliminate virus propagation in the network.

  20. Mechanical Stresses in Carotid Plaques

    DEFF Research Database (Denmark)

    Samuel, Samuel Alberg

    simulationer, som tillod beregning af longitudinelle stress-niveauer i den fibrøse kappe. Afhandlingen indeholder tre artikler, som beskriver denne metode. Den første; “Mechanical Stresses in Carotid Plaques using MRI-Based Fluid Structure Interaction Models”, beskriver i detaljer metoden til at danne de...

  1. Nonlinear physical systems spectral analysis, stability and bifurcations

    CERN Document Server

    Kirillov, Oleg N

    2013-01-01

    Bringing together 18 chapters written by leading experts in dynamical systems, operator theory, partial differential equations, and solid and fluid mechanics, this book presents state-of-the-art approaches to a wide spectrum of new and challenging stability problems.Nonlinear Physical Systems: Spectral Analysis, Stability and Bifurcations focuses on problems of spectral analysis, stability and bifurcations arising in the nonlinear partial differential equations of modern physics. Bifurcations and stability of solitary waves, geometrical optics stability analysis in hydro- and magnetohydrodynam

  2. Kidney function during arterial chemoreceptor stimulation. I. Influence of unilateral renal nerve section, bilateral cervical vagotomy, constant artificial ventilation, and carotid body chemoreceptor inactivation.

    Science.gov (United States)

    Schmidt, M; Ledderhos, C; Honig, A

    1985-01-01

    The reactions of renal hemodynamics and excretory function elicited by perfusion of the vascularly isolated carotid bodies with venous blood were studied in four groups of chloralosed cats in which the Nn. vagi, the breathing reactions, and the carotid body chemoreceptors were excluded successively. The kidney function was determined using clearance-techniques in both the innervated right and denervated left kidneys. In the animals with intact carotid chemoreceptors perfusion of the carotid bifurcations with venous blood caused a weak (4-6 mm Hg on the average) and transient increase of the mean systemic arterial blood pressure as well as a vasoconstriction and a fall of the blood flow and glomerular filtration rate in the innervated kidneys. In the spontaneously breathing animals carotid body chemoreceptor stimulation effected a rise of fractional sodium excretion only in the denervated kidneys whereas the relaxed and constantly ventilated cats showed a natriuretic response both at the innervated and denervated side. The reactions of renal excretory function did not correlate with those of renal hemodynamics. Vagotomy, relaxation, and constant artificial ventilation failed to abolish the responses elicited by stimulation of the chemoreceptors. Inactivation of the carotid body chemoreceptors by injecting acetic acid into the vascularly isolated carotid sinuses prevented both the hemodynamic and tubular reactions due to hypoxic-hypercapnic perfusion of the carotid bodies. The findings suggest that the arterial chemoreceptors control kidney function by specific reflex mechanisms. The influence of the carotid body chemoreceptors on kidney vasculature is mediated by the efferent renal nerves, whereas the control of renal tubular sodium reabsorption requires hormone action.

  3. Bifurcation and stability for a nonlinear parabolic partial differential equation

    Science.gov (United States)

    Chafee, N.

    1973-01-01

    Theorems are developed to support bifurcation and stability of nonlinear parabolic partial differential equations in the solution of the asymptotic behavior of functions with certain specified properties.

  4. Hopf bifurcation for tumor-immune competition systems with delay

    Directory of Open Access Journals (Sweden)

    Ping Bi

    2014-01-01

    Full Text Available In this article, a immune response system with delay is considered, which consists of two-dimensional nonlinear differential equations. The main purpose of this paper is to explore the Hopf bifurcation of a immune response system with delay. The general formula of the direction, the estimation formula of period and stability of bifurcated periodic solution are also given. Especially, the conditions of the global existence of periodic solutions bifurcating from Hopf bifurcations are given. Numerical simulations are carried out to illustrate the the theoretical analysis and the obtained results.

  5. Sequences of gluing bifurcations in an analog electronic circuit

    Energy Technology Data Exchange (ETDEWEB)

    Akhtanov, Sayat N.; Zhanabaev, Zeinulla Zh. [Physico-Technical Department, Al Farabi Kazakh National University, Al Farabi Av. 71, Almaty, 050038 Kazakhstan (Kazakhstan); Zaks, Michael A., E-mail: zaks@math.hu-berlin.de [Institute of Mathematics, Humboldt University, Rudower Chaussee 25, D-12489 Berlin (Germany)

    2013-10-01

    We report on the experimental investigation of gluing bifurcations in the analog electronic circuit which models a dynamical system of the third order: Lorenz equations with an additional quadratic nonlinearity. Variation of one of the resistances in the circuit changes the coefficient at this nonlinearity and replaces the Lorenz route to chaos by a different scenario which leads, through the sequence of homoclinic bifurcations, from periodic oscillations of the voltage to the irregular ones. Every single bifurcation “glues” in the phase space two stable periodic orbits and creates a new one, with the doubled length: a sequence of such bifurcations results in the birth of the chaotic attractor.

  6. Bifurcations in two coupled Rössler systems

    DEFF Research Database (Denmark)

    Rasmussen, J; Mosekilde, Erik; Reick, C.

    1996-01-01

    The paper presents a detailed bifurcation analysis of two symmetrically coupled Rössler systems. The symmetry in the coupling does not allow any one direction to become preferred, and the coupled system is therefore an example of a dissipative system that cannot be considered as effectively one......-dimensional. The results are presented in terms of one- and two-parmeter bifurcation diagrams. A particularly interesting finding is the replacement of some of the period-doubling bifurcations by torus bifurcations. By virtue of this replacement, instead of a Feigenbaum transition to chaos a transition via torus...

  7. Fate of the external carotid artery following carotid interventions.

    Science.gov (United States)

    Casey, Kevin; Zhou, Wei; Tedesco, Maureen M; Al-Khatib, Weesam K; Hernandez-Boussard, Tina; Bech, Fritz

    2009-01-01

    The external carotid artery (ECA) is an important collateral pathway for cerebral blood flow. Carotid artery stenting (CAS) typically crosses the ECA, while carotid endarterectomy (CEA) includes deliberate ECA plaque removal. The purpose of the present study was to compare the long-term patency of the ECA following CAS and CEA as determined by carotid duplex ultrasound. Duplex ultrasounds and hospital records were reviewed for consecutive patients undergoing CAS between February 2002 and April 2008, and were compared with those undergoing CEA in the same time period. Preoperative and postoperative ECA peak systolic velocities were normalized to the common carotid artery (CCA) as ECA/CCA ratios. A significant (80% or greater) ECA stenosis was defined as an ECA/CCA ratio of 4.0. A change of ratio by more than 1 was defined as significant. Data were analyzed using Student's t test and χ(2) analysis. A total of 86 CAS procedures in 83 patients were performed (81 men, mean age 69.9 years). Among them, 38.4% of patients had previous CEA, 9.6% of whom had contralateral internal carotid artery occlusion. Sixty-seven CAS and 65 CEA patients with complete duplex data in the same time period were included in the analyses. There was no difference in the incidence of severe ECA stenosis on preoperative ultrasound evaluations. During a mean follow-up of 34 months (range four to 78 months), three postprocedure ECA occlusions were found in the CAS group. The likelihood of severe stenosis or occlusion following CAS was 28.3%, compared with 11% following CEA (PECA status. Reduction in the patient's degree of ECA stenosis was observed in 9.4% of CAS versus 26.6% of CEA patients. Overall, immediate postoperative ratios of both groups were slightly improved, but there was a trend of more disease progression in the CAS group during follow-up. CAS is associated with a higher incidence of post-procedure ECA stenosis. Despite the absence of neurological symptoms, a trend toward late

  8. After Science and Technology Studies: Recomposing the Psychological and Experience Before the Bifurcation of Nature

    Directory of Open Access Journals (Sweden)

    Patricio Rojas

    2017-11-01

    Full Text Available In this article I present a theoretical inquiry into the ways in which we can understand the psychological and experience, considering the challenges posed to these notions by the field of science and technology studies (STS. STS have developed a form of constructivist critique that rejects the 'bifurcation of nature', that is to say, the divide of the world between primary qualities -the material world, reality itself-, and secondary qualities -experience, consciousness and human affairs. Taking as guideline theoretical questions that emerged during an empirical research about public health users’ “experience of being a patient”, I argue that the critique of the bifurcation of nature often assumes notions of the psychological and human experience that positions them as a dead end. I claim that process philosophy provides useful tools to refute this simplification, articulating the psychological as a constant flux of co-affectation of the human and the world, where experience is not separated from nature.

  9. Correlation between US-PSV and 64-Row MDCTA with Advanced Vessel Analysis in the Quantification of 50–70% Carotid Artery Stenosis

    Directory of Open Access Journals (Sweden)

    Matteo Stefanini

    2012-01-01

    Full Text Available Purpose. To correlate ultrasonographic peak systolic velocity (US-PSV and 64-row multidetector computed tomography angiography (MDCTA with advanced vessel analysis (AVA software in the quantification of 50–70% carotid artery stenosis. Materials and methods. 199 consecutive patients (247 arteries with internal carotid artery (ICA or third proximal bifurcation stenosis. Each patient was studied by duplex US (DUS and 64-row MDCTA with AVA software. Results. DUS showed PSV measurements less than 125 cm/s in 51 carotid stenosis and a value greater than this in 196 arteries. 64-row MDCTA AVA software showed a grade of stenosis less than 50% in 42 carotid arteries while a greater 70% was found in 4 carotid arteries; then, carotid arteries with stenosis percentage between 50% and 70% were 201. Linear regression analysis showed a good linear correlation (=0.88 between MDCTA-AVA software percentage stenosis and PSV: between 50% grade of stenosis and PSV value corresponding to 133,6 cm/sec and between 70% stenosis and PSV value corresponding to 268 cm/sec. The sensitivity, specificity, positive predictive value(PPV, negative predictive value(NPV of this analysis were 93%, 82%, 97%, 75%, respectively. Conclusion. Linear correlation between PSV data and grade of stenosis from 50% to 70% obtained with 64-row MDCTA AVA software. Main PSV value corresponding to 50% and 70% grade of stenosis at AVA analysis.

  10. Correlation between US-PSV and 64-Row MDCTA with Advanced Vessel Analysis in the Quantification of 50-70% Carotid Artery Stenosis.

    Science.gov (United States)

    Stefanini, Matteo; Gaspari, Eleonora; Boi, Luca; Del Giudice, Costantino; Mastrangeli, Roberta; Nucera, Francesca; Simonetti, Giovanni

    2012-01-01

    Purpose. To correlate ultrasonographic peak systolic velocity (US-PSV) and 64-row multidetector computed tomography angiography (MDCTA) with advanced vessel analysis (AVA) software in the quantification of 50-70% carotid artery stenosis. Materials and methods. 199 consecutive patients (247 arteries) with internal carotid artery (ICA) or third proximal bifurcation stenosis. Each patient was studied by duplex US (DUS) and 64-row MDCTA with AVA software. Results. DUS showed PSV measurements less than 125 cm/s in 51 carotid stenosis and a value greater than this in 196 arteries. 64-row MDCTA AVA software showed a grade of stenosis less than 50% in 42 carotid arteries while a greater 70% was found in 4 carotid arteries; then, carotid arteries with stenosis percentage between 50% and 70% were 201. Linear regression analysis showed a good linear correlation (r = 0.88) between MDCTA-AVA software percentage stenosis and PSV: between 50% grade of stenosis and PSV value corresponding to 133,6 cm/sec and between 70% stenosis and PSV value corresponding to 268 cm/sec. The sensitivity, specificity, positive predictive value(PPV), negative predictive value(NPV) of this analysis were 93%, 82%, 97%, 75%, respectively. Conclusion. Linear correlation between PSV data and grade of stenosis from 50% to 70% obtained with 64-row MDCTA AVA software. Main PSV value corresponding to 50% and 70% grade of stenosis at AVA analysis.

  11. Periodic orbits near a bifurcating slow manifold

    DEFF Research Database (Denmark)

    Kristiansen, Kristian Uldall

    2015-01-01

    (\\epsilon^{1/3})$-distance from the union of the normally elliptic slow manifolds that occur as a result of the bifurcation. Here $\\epsilon\\ll 1$ measures the time scale separation. These periodic orbits are predominantly unstable. The proof is based on averaging of two blowup systems, allowing one to estimate...... the effect of the singularity, combined with results on asymptotics of the second Painleve equation. The stable orbits of smallest amplitude that are {persistently} obtained by these methods remain slightly further away from the slow manifold being distant by an order $\\mathcal O(\\epsilon^{1/3}\\ln^{1/2}\\ln...

  12. Differential effects of carotid artery stenting versus carotid endarterectomy on external carotid artery patency.

    Science.gov (United States)

    Woo, Edward Y; Karmacharya, Jagajan; Velazquez, Omaida C; Carpenter, Jeffrey P; Skelly, Christopher L; Fairman, Ronald M

    2007-04-01

    To determine the effect of stent coverage of the external carotid artery (ECA) after carotid artery stenting (CAS) compared to eversion endarterectomy of the ECA after carotid endarterectomy (CEA). The records of 101 CAS and 165 CEA procedures performed over 2 years were reviewed. Duplex velocities and history and physical examinations were taken prior to the procedure, at 1 month, and at 6-month intervals subsequently. CAS was performed by extending the stent across the internal carotid artery (ICA) lesion into the common carotid artery (CCA) thereby covering the ECA. CEA was performed with eversion endarterectomy of the ECA. The mean peak systolic velocities (PSV) in the ICA pre-CAS and pre-CEA were 361 and 352 cm/s, respectively. In terms of CAS, there was a significant increase in ECA velocities versus baseline at 12 (p = 0.009), 18 (p = 0.00001), and 24 (p = 0.005) months. In the CEA group, there was a significant decrease in ECA velocities versus baseline at 1 (p = 0.01) and 6 (p = 0.004) months. There were 2 occluded ECAs in follow-up in the CAS group and none in the CEA group. No significant differences were noted when comparing preprocedural ICA or ECA velocities. However, at the 1-, 6-, and 12-month intervals, the ECA velocities in the CAS group were significantly higher than in the CEA group (p = 0.03, p = 0.001, and p = 0.0004, respectively). There were no neurological symptoms in any patients during the study period. Although progressive stenosis of the ECA is noted during CAS, the ECA usually does not occlude. Furthermore, there are no associated neurological symptoms. Thus, apprehension for progressive ECA occlusion should not be a contraindication to CAS. In addition, concern for ECA coverage should not deter stent extension from the ICA to the CCA during CAS.

  13. Serum Osteoprotegerin Is Associated With Calcified Carotid Plaque

    Science.gov (United States)

    Kwon, Ami; Choi, Yun-Seok; Choi, Yong-Won; Chung, Woo-Baek; Park, Chul-Soo; Chung, Wook-Sung; Lee, Man-Young; Youn, Ho-Joong

    2016-01-01

    Abstract Osteoprotegerin (OPG) is a kind of tumor necrosis factor, which is related to bone metabolism and vascular calcification. The increase of Osteoprotegerin concentration in serum is related to cardiovascular diseases in humans. The purpose of this study was to figure out the relevance between osteoprotegerin in serum and carotid calcification. Serum OPG concentrations were compared in 145 patients who underwent carotid sonography (average age: 68 ± 9 years old, male: female = 81:64). A calcified plaque (CP) (37 people [27%]), a noncalcified plaque (NCP) (54 people [37%]), and a nonplaque (NP) (54 people [37%]) were classified for this study. No significant differences among 3 groups were demonstrated in the distribution of age, diabetes, high blood pressure, and hyperlipidemia. Serum osteoprotegerin concentrations were significantly increased in CP group rather than NCP group or NP group; (median [interquartile range], 4016 [1410] vs 3210 [1802] pg/mL, P osteoprotegerin concentrations did not indicate a significant difference between NCP Group or NP Group. This study had proved that patient group accompanied with carotid calcification in carotid artery disease had an increased serum OPG concentration, so it could consider that OPG plays an important function on calcification related to arteriosclerosis. PMID:27082605

  14. Acute internal carotid artery occlusion after carotid endarterectomy

    Directory of Open Access Journals (Sweden)

    Masatoshi Yunoki

    2016-09-01

    Full Text Available We report two cases of acute carotid artery (CA occlusion following carotid endarterectomy (CEA. Case 1: a 58-year-old man was admitted with transient right-sided hemiparesis. Magnetic resonance imaging (MRI and MR angiography (MRA revealed cerebral infarction in the left cerebral hemisphere and left CA stenosis. Ten days after admission, he underwent CEA. 24 h after surgery, he developed right hemiplegia. MRI and MRA demonstrated a slightly enlarged infarction and left internal carotid artery (ICA occlusion. Emergency reoperation was performed and complete recanalization achieved. The patient made a clinically significant recovery. Case 2: a 65 year-old man underwent a right-sided CEA for an asymptomatic 80% CA stenosis. 48 h after surgery, his family noticed he was slightly disorientated. MRI and MRA revealed multiple infarctions and right ICA occlusion. He was treated with antiplatelet therapy without reoperation because sufficient cross-flow from the left ICA through the anterior communicating artery was demonstrated by angiography, and his neurological symptoms were mild. His symptoms gradually alleviated and he was discharged 14 days after surgery. With ICA occlusion after CEA, immediate re-operation is mandatory with severe neurological symptoms, whereas individualized judgement is needed when the symptoms are mild.

  15. Carotid endarterectomy and carotid artery stenting utilization trends over time.

    Science.gov (United States)

    Skerritt, Matthew R; Block, Robert C; Pearson, Thomas A; Young, Kate C

    2012-03-29

    Carotid endarterectomy (CEA) has been the standard in atherosclerotic stroke prevention for over 2 decades. More recently, carotid artery stenting (CAS) has emerged as a less invasive alternative for revascularization. The purpose of this study was to investigate whether an increase in stenting parallels a decrease in endarterectomy, if there are specific patient factors that influence one intervention over the other, and how these factors may have changed over time. Using a nationally representative sample of US hospital discharge records, data on CEA and CAS procedures performed from 1998 to 2008 were obtained. In total, 253,651 cases of CEA and CAS were investigated for trends in utilization over time. The specific data elements of age, gender, payer source, and race were analyzed for change over the study period, and their association with type of intervention was examined by multiple logistic regression analysis. Rates of intervention decreased from 1998 to 2008 (P use displayed a significant downward trend (P use over the study period (P time, the proportion of white patients who received intervention decreased significantly (P gender, white race, and earlier in the study period were significant positive predictors of CEA use. Rates of carotid revascularization have decreased over time, although this has been the result of a reduction in CEA despite an overall increase in CAS. Among the specific patient factors analyzed, age, gender, race, and time were significantly associated with the utilization of these two interventions.

  16. [Surgical treatment of tumors of the carotid body with reconstruction of the internal carotid artery].

    Science.gov (United States)

    Reparaz, L; Magallón, P; Riera, L; Capilla, M T; Merino, M J; Martínez, I; Hernández, A; Sáez, L; Alamo, O; Jiménez Cossío, J A

    1990-01-01

    The experience about treatment in infiltrating tumors of Carotid Corpus, III Degree (Shamblin), is presented. Different methods of carotid reconstruction, and biologic and evolutive characteristics are emphasized, discussing preoperatory study and surgical technics.

  17. [Sports-related carotid artery dissection].

    Science.gov (United States)

    Berrouschot, J; Bormann, A; Routsi, D; Stoll, A

    2009-09-01

    Sports-related carotid artery dissection are very rare and were described in different kinds of sports. We report on a 45-year old man who suffered bilateral brain infarctions caused by bilateral extracranial internal carotid artery dissection after excessive weight lifting in a gym. As possible trigger factors for the dissections we assumed the abrupt extension of the neck during weight lifting and the frequent Valsalva manoeuvers with massive rise in the pressure in the carotid artery system. The patient underwent angioplasty and stenting of the stenosis of right carotid artery, the primarily occluded left carotid artery recanalized spontaneously. Secondary prevention was established by platelet aggregation inhibitors. The patient recovered completely. The pathogenesis of sports-related dissections is multifactorial. In addition to sporting activities hereditary or acquired structural aberrations in the arterial walls could be discussed. Acute focal neurological symptoms after sport should always focus on carotid or vertebral artery dissection. (c) Georg Thieme Verlag KG Stuttgart-New York.

  18. A Case of Hybrid Carotid Revascularization

    Directory of Open Access Journals (Sweden)

    Hari Prasad

    2017-04-01

    Full Text Available Cerebral infarction attributed to extracranial carotid and vertebral artery disease is defined as clinical stroke with evidence of infarction on brain imaging associated with >50% stenosis or occlusion of an extracranial carotid or vertebral artery documented by noninvasive imaging or angiography. Radiation to the neck poses a high risk for developing carotid stenosis. Even though the standard treatment for extracranial artery stenosis is carotid endarterectomy (CEA, higher rates of cranial nerve injury and wound complications including infection limit CEA applications in patients with prior radiation. Carotid angioplasty and stenting (CAS should be considered as an alternative to CEA for those patients with high surgical risk. We report a case of CAS in a patient who had prior neck radiation for malignancy, presenting with carotid stenosis.

  19. Droplet Breakup Dynamics in Bi-Layer Bifurcating Microchannel

    Directory of Open Access Journals (Sweden)

    Yong Ren

    2018-01-01

    Full Text Available Breakup of droplets at bi-layer bifurcating junction in polydimethylsiloxane (PDMS microchannel has been investigated by experiments and numerical simulation. The pressure drop in bi-layer bifurcating channel was investigated and compared with single-layer bifurcating channel. Daughter droplet size variation generated in bi-layer bifurcating microchannel was analyzed. The correlation was proposed to predict the transition between breakup and non-breakup conditions of droplets in bi-layer bifurcating channel using a phase diagram. In the non-breakup regime, droplets exiting port can be switched via tuning flow resistance by controlling radius of curvature, and or channel height ratio. Compared with single-layer bifurcating junction, 3-D cutting in diagonal direction from bi-layer bifurcating junction induces asymmetric fission to form daughter droplets with distinct sizes while each size has good monodispersity. Lower pressure drop is required in the new microsystem. The understanding of the droplet fission in the novel microstructure will enable more versatile control over the emulsion formation, fission and sorting. The model system can be developed to investigate the encapsulation and release kinetics of emulsion templated particles such as drug encapsulated microcapsules as they flow through complex porous media structures, such as blood capillaries or the porous tissue structures, which feature with bifurcating junctions.

  20. Bifurcation of learning and structure formation in neuronal maps

    DEFF Research Database (Denmark)

    Marschler, Christian; Faust-Ellsässer, Carmen; Starke, Jens

    2014-01-01

    to map formation in the laminar nucleus of the barn owl's auditory system. Using equation-free methods, we perform a bifurcation analysis of spatio-temporal structure formation in the associated synaptic-weight matrix. This enables us to analyze learning as a bifurcation process and follow the unstable...

  1. Emergence and bifurcations of Lyapunov manifolds in nonlinear wave equations

    NARCIS (Netherlands)

    Bakri, Taoufik; Meijer, Hil Gaétan Ellart; Verhulst, Ferdinand

    2009-01-01

    Persistence and bifurcations of Lyapunov manifolds can be studied by a combination of averaging-normalization and numerical bifurcation methods. This can be extended to infinite-dimensional cases when using suitable averaging theorems. The theory is applied to the case of a parametrically excited

  2. Sediment discharge division at two tidally influenced river bifurcations

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Vermeulen, B.; Hidayat, H.

    2013-01-01

    [1] We characterize and quantify the sediment discharge division at two tidally influenced river bifurcations in response to mean flow and secondary circulation by employing a boat-mounted acoustic Doppler current profiler (ADCP), to survey transects at bifurcating branches during a semidiurnal

  3. Views on the Hopf bifurcation with respect to voltage instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Roa-Sepulveda, C.A. [Universidad de Concepcion, Concepcion (Chile). Dept. de Ingenieria Electrica; Knight, U.G. [Imperial Coll. of Science and Technology, London (United Kingdom). Dept. of Electrical and Electronic Engineering

    1994-12-31

    This paper presents a sensitivity study of the Hopf bifurcation phenomenon which can in theory appear in power systems, with reference to the dynamics of the process and the impact of demand characteristics. Conclusions are drawn regarding power levels at which these bifurcations could appear and concern the concept of the imaginary axis as a `hard` limit eigenvalue analyses. (author) 20 refs., 31 figs.

  4. Quantum Localization near Bifurcations in Classically Chaotic Systems

    CERN Document Server

    Varga, I; Eckhardt, B

    1999-01-01

    We show that strongly localized wave functions occur around classical bifurcations. Near a saddle node bifurcation the scaling of the inverse participation ratio on Planck's constant and the dependence on the parameter is governed by an Airy function. Analytical estimates are supported by numerical calculations for the quantum kicked rotor.

  5. Analysis of Vehicle Steering and Driving Bifurcation Characteristics

    Directory of Open Access Journals (Sweden)

    Xianbin Wang

    2015-01-01

    Full Text Available The typical method of vehicle steering bifurcation analysis is based on the nonlinear autonomous vehicle model deriving from the classic two degrees of freedom (2DOF linear vehicle model. This method usually neglects the driving effect on steering bifurcation characteristics. However, in the steering and driving combined conditions, the tyre under different driving conditions can provide different lateral force. The steering bifurcation mechanism without the driving effect is not able to fully reveal the vehicle steering and driving bifurcation characteristics. Aiming at the aforementioned problem, this paper analyzed the vehicle steering and driving bifurcation characteristics with the consideration of driving effect. Based on the 5DOF vehicle system dynamics model with the consideration of driving effect, the 7DOF autonomous system model was established. The vehicle steering and driving bifurcation dynamic characteristics were analyzed with different driving mode and driving torque. Taking the front-wheel-drive system as an example, the dynamic evolution process of steering and driving bifurcation was analyzed by phase space, system state variables, power spectral density, and Lyapunov index. The numerical recognition results of chaos were also provided. The research results show that the driving mode and driving torque have the obvious effect on steering and driving bifurcation characteristics.

  6. Seasonal Variation of the North/South Equatorial Current Bifurcation

    Science.gov (United States)

    Chen, Z.

    2016-02-01

    The seasonal variation of the North/South Equatorial Current (NEC/SEC) bifurcation off the Philippine/Madagascar/Australian coast is investigated. It is shown that the seasonal cycles of the NEC/SEC bifurcation are generally analogous to each other, all of which shift synchronously back and forth seasonally and arrive at their southernmost positions in boreal late spring and early summer. It is demonstrated that the linear, reduced gravity, long Rossby model, which works well for the NEC bifurcation, is insufficient to reproduce the seasonal cycles of the SEC bifurcation off the Madagascar/Australian coast particularly in their south-north migrations. This can be attributed to the existence of the isolated island in the Madagascar case and the seasonally-varying wind forcing around the Australian coast, while they are almost absent in the NEC bifurcation case. Without considering the existence of an island and the alongshore winds, we propose a simple bifurcation model under the framework of linear Rossby wave dynamics. It is found that the seasonal bifurcation latitude is predominantly determined by the spatial pattern of the wind and baroclinic Rossby wave propagation. This model explains the roles of local/remote wind forcing and baroclinic adjustment in the south-north migration and peak seasons of the bifurcation latitude.

  7. Energy conservation via electron bifurcating ferredoxin reduction and proton/Na(+) translocating ferredoxin oxidation.

    Science.gov (United States)

    Buckel, Wolfgang; Thauer, Rudolf K

    2013-02-01

    The review describes four flavin-containing cytoplasmatic multienzyme complexes from anaerobic bacteria and archaea that catalyze the reduction of the low potential ferredoxin by electron donors with higher potentials, such as NAD(P)H or H(2) at ≤ 100 kPa. These endergonic reactions are driven by concomitant oxidation of the same donor with higher potential acceptors such as crotonyl-CoA, NAD(+) or heterodisulfide (CoM-S-S-CoB). The process called flavin-based electron bifurcation (FBEB) can be regarded as a third mode of energy conservation in addition to substrate level phosphorylation (SLP) and electron transport phosphorylation (ETP). FBEB has been detected in the clostridial butyryl-CoA dehydrogenase/electron transferring flavoprotein complex (BcdA-EtfBC), the multisubunit [FeFe]hydrogenase from Thermotoga maritima (HydABC) and from acetogenic bacteria, the [NiFe]hydrogenase/heterodisulfide reductase (MvhADG-HdrABC) from methanogenic archaea, and the transhydrogenase (NfnAB) from many Gram positive and Gram negative bacteria and from anaerobic archaea. The Bcd/EtfBC complex that catalyzes electron bifurcation from NADH to the low potential ferredoxin and to the high potential crotonyl-CoA has already been studied in some detail. The bifurcating protein most likely is EtfBC, which in each subunit (βγ) contains one FAD. In analogy to the bifurcating complex III of the mitochondrial respiratory chain and with the help of the structure of the human ETF, we propose a conformational change by which γ-FADH(-) in EtfBC approaches β-FAD to enable the bifurcating one-electron transfer. The ferredoxin reduced in one of the four electron bifurcating reactions can regenerate H(2) or NADPH, reduce CO(2) in acetogenic bacteria and methanogenic archaea, or is converted to ΔμH(+)/Na(+) by the membrane-associated enzyme complexes Rnf and Ech, whereby NADH and H(2) are recycled, respectively. The mainly bacterial Rnf complexes couple ferredoxin oxidation by NAD(+) with

  8. DURAL CAROTID-CAVERNOUS FISTULAS

    Directory of Open Access Journals (Sweden)

    Barbara Cvenkel

    2002-12-01

    Full Text Available Background. Dural carotid-cavernous sinus fistulas (CCF are communications fed by meningeal branches of the intracavernous internal carotid artery (ACI or/and external carotid artery (ACE. In contrast to typical CCF, the arteriovenous shunting of blood is usually low flow and low pressure. Spontaneous dural CCF are more common in postmenopausal women. Aetiology is unknown, but congenital malformation or rupture of thin-walled dural arteries within venous sinuses is believed to be the cause.Case reports. 3 cases lacking the typical clinical signs of CCF who had been treated as chronic conjunctivitis, myositis of the extraocular muscle and orbital pseudotumour are presented. Clinical presentation depends on the direction and magnitude of fistular flow and on the anatomy of the collateral branches. If increased blood flow is directed anteriorly in ophthalmic veins the signs of orbito-ocular congestion are present (»redeyed shunt syndrome«. Drainage primarly in the inferior petrosal sinus may cause painful oculomotor and abducens palsies without signs of ocular congestion (»white-eyed shunt syndrome«. Also different therapeutic approaches as well as possible complications are described.Conclusions. For definite diagnosis angiography is obligatory and is also therapeutic as one third to one half of dural CCF close spontaneously. Because of potential severe eye and systemic complications, surgical intervention is indicated only in cases with uncontrolled secondary glaucoma and hypoxic retinopathy.

  9. Hopf Bifurcation of Compound Stochastic van der Pol System

    Directory of Open Access Journals (Sweden)

    Shaojuan Ma

    2016-01-01

    Full Text Available Hopf bifurcation analysis for compound stochastic van der Pol system with a bound random parameter and Gaussian white noise is investigated in this paper. By the Karhunen-Loeve (K-L expansion and the orthogonal polynomial approximation, the equivalent deterministic van der Pol system can be deduced. Based on the bifurcation theory of nonlinear deterministic system, the critical value of bifurcation parameter is obtained and the influence of random strength δ and noise intensity σ on stochastic Hopf bifurcation in compound stochastic system is discussed. At last we found that increased δ can relocate the critical value of bifurcation parameter forward while increased σ makes it backward and the influence of δ is more sensitive than σ. The results are verified by numerical simulations.

  10. Critical bifurcation surfaces of 3D discrete dynamics

    Directory of Open Access Journals (Sweden)

    Michael Sonis

    2000-01-01

    Full Text Available This paper deals with the analytical representation of bifurcations of each 3D discrete dynamics depending on the set of bifurcation parameters. The procedure of bifurcation analysis proposed in this paper represents the 3D elaboration and specification of the general algorithm of the n-dimensional linear bifurcation analysis proposed by the author earlier. It is proven that 3D domain of asymptotic stability (attraction of the fixed point for a given 3D discrete dynamics is bounded by three critical bifurcation surfaces: the divergence, flip and flutter surfaces. The analytical construction of these surfaces is achieved with the help of classical Routh–Hurvitz conditions of asymptotic stability. As an application the adjustment process proposed by T. Puu for the Cournot oligopoly model is considered in detail.

  11. Endarterectomy for a symptomatic carotid web.

    Science.gov (United States)

    Phair, John; Trestman, Eric B; Yean, Chetra; Lipsitz, Evan C

    2017-10-01

    Background We report a symptomatic carotid web successfully treated with carotid endarterectomy. A healthy 43-year-old woman presented with acute-onset left-sided weakness. Carotid web was evident on computed tomography angiography as a focal filling defect in the right common carotid artery. This right common carotid artery web extended into the ICA created an eddy resulting in turbulent flow. Subsequent acute embolus formation led to embolization and acute stroke. Method Review of the literature was performed using Medline Plus and PubMed databases. Result The patient underwent carotid endarterectomy with primary closure. Procedure was well tolerated and there was an uneventful recovery. Conclusion Arterial webs are a rare arteriopathy and a usual arrangement of fibromuscular intralumenal in-growth with unclear etiology. It is however, an important potential etiology of stroke in patients without traditional atherosclerotic risk factors. Carotid web and atypical carotid fibromuscular dysplasia should be considered in young, otherwise healthy patients presenting with stroke and without the typical risk factors for atherosclerotic carotid disease and stroke.

  12. 3D Isotropic MR Culprit Plaque Visualization of Carotid Plaque Edema and Hemorrhage with Motion Sensitized Blood Suppression

    DEFF Research Database (Denmark)

    Søvsø Szocska Hansen, Esben; Pedersen, Steen Fjord; Bloch, Lars Ø.

    2014-01-01

    hemorrhage and plaque edema may represent advanced stages of atherosclerosis[1, 2]. In this study, we present a novel multi-contrast 3D motion sensitized black-blood CMR imaging sequence, which detects both plaque edema and hemorrhage with positive contrast. Subjects and Methods The 3D imaging sequence...... formatting in all three dimensions was possible to provide a comprehensive and exhaustive evaluation of the vessel wall. For the symptomatic carotid artery plaque, hyperintensive signal intensity was detected with a signal-to-noise ratio (SNR) that was significantly higher compared to the vessel wall...... proximal to the bifurcation (43.36±8.01 versus 16.91±3.49, respectively P plaque compared to the proximal carotid vessel wall was 26.45±4.60 and CNR plaque...

  13. Climate bifurcation during the last deglaciation?

    Directory of Open Access Journals (Sweden)

    T. M. Lenton

    2012-07-01

    Full Text Available There were two abrupt warming events during the last deglaciation, at the start of the Bølling-Allerød and at the end of the Younger Dryas, but their underlying dynamics are unclear. Some abrupt climate changes may involve gradual forcing past a bifurcation point, in which a prevailing climate state loses its stability and the climate tips into an alternative state, providing an early warning signal in the form of slowing responses to perturbations, which may be accompanied by increasing variability. Alternatively, short-term stochastic variability in the climate system can trigger abrupt climate changes, without early warning. Previous work has found signals consistent with slowing down during the last deglaciation as a whole, and during the Younger Dryas, but with conflicting results in the run-up to the Bølling-Allerød. Based on this, we hypothesise that a bifurcation point was approached at the end of the Younger Dryas, in which the cold climate state, with weak Atlantic overturning circulation, lost its stability, and the climate tipped irreversibly into a warm interglacial state. To test the bifurcation hypothesis, we analysed two different climate proxies in three Greenland ice cores, from the Last Glacial Maximum to the end of the Younger Dryas. Prior to the Bølling warming, there was a robust increase in climate variability but no consistent slowing down signal, suggesting this abrupt change was probably triggered by a stochastic fluctuation. The transition to the warm Bølling-Allerød state was accompanied by a slowing down in climate dynamics and an increase in climate variability. We suggest that the Bølling warming excited an internal mode of variability in Atlantic meridional overturning circulation strength, causing multi-centennial climate fluctuations. However, the return to the Younger Dryas cold state increased climate stability. We find no consistent evidence for slowing down during the Younger Dryas, or in a longer

  14. Climate bifurcation during the last deglaciation?

    Science.gov (United States)

    Lenton, T. M.; Livina, V. N.; Dakos, V.; Scheffer, M.

    2012-07-01

    There were two abrupt warming events during the last deglaciation, at the start of the Bølling-Allerød and at the end of the Younger Dryas, but their underlying dynamics are unclear. Some abrupt climate changes may involve gradual forcing past a bifurcation point, in which a prevailing climate state loses its stability and the climate tips into an alternative state, providing an early warning signal in the form of slowing responses to perturbations, which may be accompanied by increasing variability. Alternatively, short-term stochastic variability in the climate system can trigger abrupt climate changes, without early warning. Previous work has found signals consistent with slowing down during the last deglaciation as a whole, and during the Younger Dryas, but with conflicting results in the run-up to the Bølling-Allerød. Based on this, we hypothesise that a bifurcation point was approached at the end of the Younger Dryas, in which the cold climate state, with weak Atlantic overturning circulation, lost its stability, and the climate tipped irreversibly into a warm interglacial state. To test the bifurcation hypothesis, we analysed two different climate proxies in three Greenland ice cores, from the Last Glacial Maximum to the end of the Younger Dryas. Prior to the Bølling warming, there was a robust increase in climate variability but no consistent slowing down signal, suggesting this abrupt change was probably triggered by a stochastic fluctuation. The transition to the warm Bølling-Allerød state was accompanied by a slowing down in climate dynamics and an increase in climate variability. We suggest that the Bølling warming excited an internal mode of variability in Atlantic meridional overturning circulation strength, causing multi-centennial climate fluctuations. However, the return to the Younger Dryas cold state increased climate stability. We find no consistent evidence for slowing down during the Younger Dryas, or in a longer spliced record of the

  15. Pre-clinical carotid atherosclerosis and sCD163 among virally suppressed HIV patients in Botswana compared with uninfected controls

    OpenAIRE

    Mosepele, Mosepele; Hemphill, Linda C.; Moloi, Walter; Moyo, Sikhulile; Nkele, Isaac; Makhema, Joseph; Bennett, Kara,; Triant, Virginia A.; Lockman, Shahin

    2017-01-01

    Objectives Human immune deficiency virus (HIV) is associated with increased cardiovascular disease (CVD) risk, yet the relationship between HIV and carotid atherosclerosis / monocyte activation among virally suppressed HIV-infected patients in sub-Saharan Africa is not well understood. Methods We measured traditional CVD risk factors, bilateral distal common carotid intima media thickness (cIMT), presence of carotid plaque and plasma sCD163 levels among virally suppressed HIV-infected adults ...

  16. Endothelial shear stress: a critical determinant of arterial remodeling and arterial stiffness in humans--a carotid 3.0-T MRI study.

    NARCIS (Netherlands)

    Duivenvoorden, R.; Bavel, E. van; Groot, E. de; Stroes, E.S.; Disselhorst, J.A.; Hutten, B.A.; Lameris, J.S.; Kastelein, J.J.; Nederveen, A.J.

    2010-01-01

    BACKGROUND: Low endothelial shear stress (ESS) elicits endothelial dysfunction. However, the relationship between ESS and arterial remodeling and arterial stiffness is unknown in humans. We developed a 3.0-T MRI protocol to evaluate the contribution of ESS to arterial remodeling and stiffness.

  17. Bifurcated intraarticular long head of biceps tendon

    Directory of Open Access Journals (Sweden)

    Vivek Pandey

    2014-01-01

    Full Text Available Though rare, many anomalous origins of long head of the biceps tendon (LHBT have been reported in the literature. Anatomic variations commonly explained are a third humeral head, anomalous insertion, congenital absence and adherence to the rotator cuff. We report a rare case who underwent shoulder arthroscopy with impingement symptoms where in LHBT was found to be bifurcated with a part attached to superior labrum and the other part to the posterior capsule of joint. Furthermore, intraarticular portion of LHBT was adherent to the undersurface of the supraspinatus tendon. Awareness of such an anatomical aberration during the shoulder arthroscopy is of great importance as it can potentially avoid unnecessary confusion and surgery.

  18. Bifurcated SEN with Fluid Flow Conditioners

    Directory of Open Access Journals (Sweden)

    F. Rivera-Perez

    2014-01-01

    Full Text Available This work evaluates the performance of a novel design for a bifurcated submerged entry nozzle (SEN used for the continuous casting of steel slabs. The proposed design incorporates fluid flow conditioners attached on SEN external wall. The fluid flow conditioners impose a pseudosymmetric pattern in the upper zone of the mold by inhibiting the fluid exchange between the zones created by conditioners. The performance of the SEN with fluid flow conditioners is analyzed through numerical simulations using the CFD technique. Numerical results were validated by means of physical simulations conducted on a scaled cold water model. Numerical and physical simulations confirmed that the performance of the proposed SEN is superior to a traditional one. Fluid flow conditioners reduce the liquid free surface fluctuations and minimize the occurrence of vortexes at the free surface.

  19. Oscillatory bifurcation for semilinear ordinary differential equations

    Directory of Open Access Journals (Sweden)

    Tetsutaro Shibata

    2016-06-01

    \\] where $f(u = u + (1/2\\sin^k u$ ($k \\ge 2$ and $\\lambda > 0$ is a bifurcation parameter. It is known that $\\lambda$ is parameterized by the maximum norm $\\alpha = \\Vert u_\\lambda\\Vert_\\infty$ of the solution $u_\\lambda$ associated with $\\lambda$ and is written as $\\lambda = \\lambda(k,\\alpha$. When we focus on the asymptotic behavior of $\\lambda(k,\\alpha$ as $\\alpha \\to \\infty$, it is natural to expect that $\\lambda(k, \\alpha \\to \\pi^2/4$, and its convergence rate is common to $k$. Contrary to this expectation, we show that $\\lambda(2n_1+1,\\alpha$ tends to $\\pi^2/4$ faster than $\\lambda(2n_2,\\alpha$ as $\\alpha \\to \\infty$, where $n_1\\ge 1,\\ n_2 \\ge 1$ are arbitrary given integers.

  20. Clausius entropy for arbitrary bifurcate null surfaces

    Science.gov (United States)

    Baccetti, Valentina; Visser, Matt

    2014-02-01

    Jacobson’s thermodynamic derivation of the Einstein equations was originally applied only to local Rindler horizons. But at least some parts of that construction can usefully be extended to give meaningful results for arbitrary bifurcate null surfaces. As presaged in Jacobson’s original article, this more general construction sharply brings into focus the questions: is entropy objectively ‘real’? Or is entropy in some sense subjective and observer-dependent? These innocent questions open a Pandora’s box of often inconclusive debate. A consensus opinion, though certainly not universally held, seems to be that Clausius entropy (thermodynamic entropy, defined via a Clausius relation {\\rm{d}}S = \\unicode{x111} Q/T) should be objectively real, but that the ontological status of statistical entropy (Shannon or von Neumann entropy) is much more ambiguous, and much more likely to be observer-dependent. This question is particularly pressing when it comes to understanding Bekenstein entropy (black hole entropy). To perhaps further add to the confusion, we shall argue that even the Clausius entropy can often be observer-dependent. In the current article we shall conclusively demonstrate that one can meaningfully assign a notion of Clausius entropy to arbitrary bifurcate null surfaces—effectively defining a ‘virtual Clausius entropy’ for arbitrary ‘virtual (local) causal horizons’. As an application, we see that we can implement a version of the generalized second law (GSL) for this virtual Clausius entropy. This version of GSL can be related to certain (nonstandard) integral variants of the null energy condition. Because the concepts involved are rather subtle, we take some effort in being careful and explicit in developing our framework. In future work we will apply this construction to generalize Jacobson’s derivation of the Einstein equations.

  1. The haemodynamic effect of carotid endarterectomy

    DEFF Research Database (Denmark)

    Nielsen, Ming-Yuan; Sillesen, H H; Jørgensen, Lisbeth

    2002-01-01

    to assess the haemodynamic effect of carotid artery surgery, and to relate postoperative changes to the state of cerebral circulation before revascularisation.......to assess the haemodynamic effect of carotid artery surgery, and to relate postoperative changes to the state of cerebral circulation before revascularisation....

  2. Microanatomy of the Supracavernous Internal Carotid - Anterior ...

    African Journals Online (AJOL)

    This anatomic variety is often associated with aneurysms and other vascular anomalies. The discovery of a case and the review of the literature allow us to evoke some embryological hypotheses. Keywords: Anterior cerebral artery, Internal carotid artery, Optic nerve, Aneuryom, Artère cérébrale antérieure, Artère carotide ...

  3. Angioplasty and stent placement - carotid artery - discharge

    Science.gov (United States)

    ... E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine . 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 60. Read More Carotid artery disease Carotid artery surgery Recovering after stroke Risks of tobacco Smoking - tips on how to quit Stent Stroke ...

  4. Medical treatment in carotid artery intervention

    NARCIS (Netherlands)

    Kolkert, J. L.; Meerwaldt, R.; Lefrandt, Johan; Geelkerken, R. H.; Zeebregts, C. J.

    2011-01-01

    Medical treatment has a pivotal role in the treatment of patients with occlusive carotid artery disease. Large trials have provided the justification for operative treatment besides medical treatment in patients with recent significant carotid artery stenosis two decades ago. Since then, medical

  5. Retrograde Suction Decompression Through Direct Puncture of the Common Carotid Artery for Paraclinoid Aneurysm.

    Science.gov (United States)

    Otani, Naoki; Wada, Kojiro; Toyooka, Terushige; Fujii, Kazuya; Ueno, Hideaki; Tomura, Satoshi; Tomiyama, Arata; Nakao, Yasuaki; Yamamoto, Takuji; Mori, Kentaro

    2016-01-01

    Surgical clipping of paraclinoid aneurysm can be very difficult because strong adhesions may hinder the dissection of the perforators and surrounding anatomical structures from the aneurysm dome. We describe our experience with using retrograde suction decompression during the clipping of paraclinoid aneurysms and discuss the relative advantages and pitfalls. This study included 23 patients with large and giant paraclinoid aneurysms who underwent surgical treatment consisting of direct clipping with suction decompression between March 2004 and August 2014. Direct puncture of the common carotid artery (CCA) was performed with a 20-gauge needle. The aneurysm was temporarily trapped by clamping of the CCA and external carotid artery (ECA), followed by temporary clipping of the intracranial internal carotid artery (ICA) distal to the aneurysm neck. Blood was then gently aspirated through a catheter introduced into the cervical ICA, resulting in collapse of the aneurysm. Therefore, safe aneurysm dissection was feasible during interruption of the blood flow, which could be maintained for up to 5 min. This procedure was repeated until dissection and clipping of the aneurysm were completed. Seven patients were admitted with SAH, 11 with asymptomatic unruptured aneurysm, and 5 with symptomatic unruptured aneurysm. The aneurysms were located on the paraclinoidal segment of the ICA in 15 cases, on the ICA-posterior communicating artery (PComA) in 6, at the ICA bifurcation in 1, and on the anterior wall of the ICA in 1. None of them suffered complications related to the CCA puncture. Surgical outcome was good recovery in 13 patients, moderate disability in 4, severe disability in 4, and vegetative state in 1. Retrograde suction decompression through direct puncture of the common carotid artery is a useful adjunct technique for the clipping of paraclinoid ICA aneurysms.

  6. FFT Bifurcation Analysis of Routes to Chaos via Quasiperiodic Solutions

    Directory of Open Access Journals (Sweden)

    L. Borkowski

    2015-01-01

    Full Text Available The dynamics of a ring of seven unidirectionally coupled nonlinear Duffing oscillators is studied. We show that the FFT analysis presented in form of a bifurcation graph, that is, frequency distribution versus a control parameter, can provide a valuable and helpful complement to the corresponding typical bifurcation diagram and the course of Lyapunov exponents, especially in context of detailed identification of the observed attractors. As an example, bifurcation analysis of routes to chaos via 2-frequency and 3-frequency quasiperiodicity is demonstrated.

  7. Optimization Design and Application of Underground Reinforced Concrete Bifurcation Pipe

    Directory of Open Access Journals (Sweden)

    Chao Su

    2015-01-01

    Full Text Available Underground reinforced concrete bifurcation pipe is an important part of conveyance structure. During construction, the workload of excavation and concrete pouring can be significantly decreased according to optimized pipe structure, and the engineering quality can be improved. This paper presents an optimization mathematical model of underground reinforced concrete bifurcation pipe structure according to real working status of several common pipe structures from real cases. Then, an optimization design system was developed based on Particle Swarm Optimization algorithm. Furthermore, take the bifurcation pipe of one hydropower station as an example: optimization analysis was conducted, and accuracy and stability of the optimization design system were verified successfully.

  8. Pulsatile flow in coronary bifurcations for different stenting techniques

    OpenAIRE

    García García, Javier; Manuel Martín, Fernando Jaime; Doce Carrasco, Y.; Castro Ruiz, F.; Crespo Martínez, Antonio; Goicolea Marin, P.; Fernandez Diaz, J.A.

    2012-01-01

    The objective of this work is to analyze the local hem odynamic changes caused in a coronary bifurcation by three different stenting techniques: simple stenting of the main vessel, simple stenting of the main vessel with kissing balloon in the side branch and culotte. To carry out this study an idealized geometry of a coronary bifurcation is used, and two bifurcation angles, 45º and 90º, are chosen as representative of the wide variety of re al configurations. In order to quantify th...

  9. The Persistence of a Slow Manifold with Bifurcation

    DEFF Research Database (Denmark)

    Kristiansen, Kristian Uldall; Palmer, P.; Robert, M.

    2012-01-01

    his paper considers the persistence of a slow manifold with bifurcation in a slow-fast two degree of freedom Hamiltonian system. In particular, we consider a system with a supercritical pitchfork bifurcation in the fast space which is unfolded by the slow coordinate. The model system is motivated...... by tethered satellites. It is shown that an almost full measure subset of a neighborhood of the slow manifold's normally elliptic branches persists in an adiabatic sense. We prove this using averaging and a blow-up near the bifurcation....

  10. Bifurcation control in the Burgers-KdV equation

    Energy Technology Data Exchange (ETDEWEB)

    Maccari, Attilio [Technical Institute ' G. Cardano' , Piazza della Resistenza 1, 00015 Monterotondo (Rome) (Italy)], E-mail: solitone@yahoo.it

    2008-03-15

    We consider the bifurcation control for the forced Burgers-KdV equation by means of delay feedback linear terms. We use a perturbation method in order to find amplitude and phase modulation equations as well as external force-response and frequency-response curves. We observe in the resonance response a saddle-node bifurcation that leads to jump and hysteresis phenomena. We compare the uncontrolled and controlled systems and demonstrate that control terms can delay or remove the occurrence of the saddle-node bifurcation and reduce the amplitude peak of the resonant response.

  11. Obesity and carotid artery remodeling

    DEFF Research Database (Denmark)

    Kozakova, M; Palombo, C; Morizzo, C

    2015-01-01

    characterized by body size-dependent increase in stroke volume (SV) and blood pressure (BP). SUBJECTS/METHODS: Common carotid artery (CCA) luminal diameter (LD), IMT and CWS were measured in three different populations in order to study: (A) cross-sectional associations between SV, BP, anthropometric parameters...... the luminal enlargement caused by body size-induced increase in SV, and therefore, to normalize the wall stress. CCA diameter in obesity could represent an additional biomarker, depicting the impact of altered hemodynamics on arterial wall....

  12. The importance of internal carotid artery occlusion tolerance test in carotid endarterectomy under locoregional anesthesia.

    Science.gov (United States)

    Dellaretti, Marcos; de Vasconcelos, Laura T; Dourado, Jules; de Souza, Renata F; Fontoura, Renato R; de Sousa, Atos A

    2016-06-01

    Carotid endarterectomy is considered a safe and effective method for preventing stroke in the short and long term in patients with severe carotid stenosis. The internal carotid artery (ICA) occlusion tolerance test was performed to evaluate cerebral tolerance during temporary carotid occlusion, defined as the capacity of the cerebral hemisphere to maintain adequate cerebral blood flow during occlusion of the ICA. Thus, the aim of the present study is to determine the importance of this test in patients undergoing carotid endarterectomy. From August 2008 to May 2015, 115 consecutive patients (39 female, 77 male) were referred for carotid endarterectomy at the Santa Casa de Belo Horizonte by the main author. Of the 115 patients who participated in the study, 107 were submitted to carotid endarterectomy. Morbi-mortality was 2.7 %. The presence of deficits during the ICA occlusion tolerance test in less than 30 s was associated with the presence of complications. Among the 104 patients who showed no deficits during the test, only one case (0.9 %) presented complications, while among the three cases that showed deficits during the test and who were submitted to carotid endarterectomy, two cases presented complications (p carotid endarterectomy under locoregional anesthesia is a safe surgical procedure. The internal carotid artery occlusion tolerance test can help identify high-risk patients who have been assigned this treatment.

  13. Variant termination of the common carotid artery: Cases of ...

    African Journals Online (AJOL)

    In all cases of trifurcation, superior thyroid artery was the third branch. The common carotid artery quadrifurcated into external, internal carotid, superior thyroid and ascending pharyngeal arteries. The pentafurcations comprised internal carotid, external carotid, superior thyroid, occipital and posterior auricular arteries.

  14. 21 CFR 882.5175 - Carotid artery clamp.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carotid artery clamp. 882.5175 Section 882.5175...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5175 Carotid artery clamp. (a) Identification. A carotid artery clamp is a device that is surgically placed around a patient's carotid artery...

  15. Bifurcation dynamics of the tempered fractional Langevin equation.

    Science.gov (United States)

    Zeng, Caibin; Yang, Qigui; Chen, YangQuan

    2016-08-01

    Tempered fractional processes offer a useful extension for turbulence to include low frequencies. In this paper, we investigate the stochastic phenomenological bifurcation, or stochastic P-bifurcation, of the Langevin equation perturbed by tempered fractional Brownian motion. However, most standard tools from the well-studied framework of random dynamical systems cannot be applied to systems driven by non-Markovian noise, so it is desirable to construct possible approaches in a non-Markovian framework. We first derive the spectral density function of the considered system based on the generalized Parseval's formula and the Wiener-Khinchin theorem. Then we show that it enjoys interesting and diverse bifurcation phenomena exchanging between or among explosive-like, unimodal, and bimodal kurtosis. Therefore, our procedures in this paper are not merely comparable in scope to the existing theory of Markovian systems but also provide a possible approach to discern P-bifurcation dynamics in the non-Markovian settings.

  16. Bifurcation dynamics of the tempered fractional Langevin equation

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Caibin, E-mail: macbzeng@scut.edu.cn; Yang, Qigui, E-mail: qgyang@scut.edu.cn [School of Mathematics, South China University of Technology, Guangzhou 510640 (China); Chen, YangQuan, E-mail: ychen53@ucmerced.edu [MESA LAB, School of Engineering, University of California, Merced, 5200 N. Lake Road, Merced, California 95343 (United States)

    2016-08-15

    Tempered fractional processes offer a useful extension for turbulence to include low frequencies. In this paper, we investigate the stochastic phenomenological bifurcation, or stochastic P-bifurcation, of the Langevin equation perturbed by tempered fractional Brownian motion. However, most standard tools from the well-studied framework of random dynamical systems cannot be applied to systems driven by non-Markovian noise, so it is desirable to construct possible approaches in a non-Markovian framework. We first derive the spectral density function of the considered system based on the generalized Parseval's formula and the Wiener-Khinchin theorem. Then we show that it enjoys interesting and diverse bifurcation phenomena exchanging between or among explosive-like, unimodal, and bimodal kurtosis. Therefore, our procedures in this paper are not merely comparable in scope to the existing theory of Markovian systems but also provide a possible approach to discern P-bifurcation dynamics in the non-Markovian settings.

  17. Bifurcation theory for hexagonal agglomeration in economic geography

    CERN Document Server

    Ikeda, Kiyohiro

    2014-01-01

    This book contributes to an understanding of how bifurcation theory adapts to the analysis of economic geography. It is easily accessible not only to mathematicians and economists, but also to upper-level undergraduate and graduate students who are interested in nonlinear mathematics. The self-organization of hexagonal agglomeration patterns of industrial regions was first predicted by the central place theory in economic geography based on investigations of southern Germany. The emergence of hexagonal agglomeration in economic geography models was envisaged by Krugman. In this book, after a brief introduction of central place theory and new economic geography, the missing link between them is discovered by elucidating the mechanism of the evolution of bifurcating hexagonal patterns. Pattern formation by such bifurcation is a well-studied topic in nonlinear mathematics, and group-theoretic bifurcation analysis is a well-developed theoretical tool. A finite hexagonal lattice is used to express uniformly distri...

  18. Defining Electron Bifurcation in the Electron-Transferring Flavoprotein Family.

    Science.gov (United States)

    Garcia Costas, Amaya M; Poudel, Saroj; Miller, Anne-Frances; Schut, Gerrit J; Ledbetter, Rhesa N; Fixen, Kathryn R; Seefeldt, Lance C; Adams, Michael W W; Harwood, Caroline S; Boyd, Eric S; Peters, John W

    2017-11-01

    Electron bifurcation is the coupling of exergonic and endergonic redox reactions to simultaneously generate (or utilize) low- and high-potential electrons. It is the third recognized form of energy conservation in biology and was recently described for select electron-transferring flavoproteins (Etfs). Etfs are flavin-containing heterodimers best known for donating electrons derived from fatty acid and amino acid oxidation to an electron transfer respiratory chain via Etf-quinone oxidoreductase. Canonical examples contain a flavin adenine dinucleotide (FAD) that is involved in electron transfer, as well as a non-redox-active AMP. However, Etfs demonstrated to bifurcate electrons contain a second FAD in place of the AMP. To expand our understanding of the functional variety and metabolic significance of Etfs and to identify amino acid sequence motifs that potentially enable electron bifurcation, we compiled 1,314 Etf protein sequences from genome sequence databases and subjected them to informatic and structural analyses. Etfs were identified in diverse archaea and bacteria, and they clustered into five distinct well-supported groups, based on their amino acid sequences. Gene neighborhood analyses indicated that these Etf group designations largely correspond to putative differences in functionality. Etfs with the demonstrated ability to bifurcate were found to form one group, suggesting that distinct conserved amino acid sequence motifs enable this capability. Indeed, structural modeling and sequence alignments revealed that identifying residues occur in the NADH- and FAD-binding regions of bifurcating Etfs. Collectively, a new classification scheme for Etf proteins that delineates putative bifurcating versus nonbifurcating members is presented and suggests that Etf-mediated bifurcation is associated with surprisingly diverse enzymes.IMPORTANCE Electron bifurcation has recently been recognized as an electron transfer mechanism used by microorganisms to maximize

  19. Can carotid stenosis be operated without arteriography? Contribution of magnetic resonance and helical computerized tomography angiography; Peut-on operer une stenose carotidienne sans arteriographie? Apport de l`angioMR et/ou de l`angioscanner helicoidal

    Energy Technology Data Exchange (ETDEWEB)

    Auffrau-Calvier, E.; Kersaint-Gilly, A. de; Desal, H.A.; Viarouge, M.P.; Havet, T. [Hopital Laennec, 44 - Nantes (France)

    1996-09-01

    The aim of this work is to ascertain the role of the magnetic resonance angiography (MRA) and to compare it with the Doppler effect, the X-ray angiography and the new method of helical computerized tomography. Seventy one carotid bifurcations in 37 patients with suspected cerebral vascular events has been evaluated with the MRA and digitalized angiography, the reference method. The obtained data corroborate the good results proposed by other authors reporting in the literature and allow to propose this examination as a new means of investigating carotid bifurcations. Work with the helical computerized tomography appears to be promising too but there are few reported series. Therefore, there appears to be two interesting points: the reliability of distinguishing between very severe stenosis and occlusion, and the fine-tuned analysis of the plaque with detection of ulcerations. When a consistent approach is used to the evaluation of the carotid bifurcation, the Willis circle and the cerebral parenchyma, the MRA can complete the Doppler echo data and the preoperative arteriography can only be used in patients when the MRA and the Doppler echo results disagree. (authors)

  20. Bunch lengthening with bifurcation in electron storage rings

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun-San; Hirata, Kohji [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    The mapping which shows equilibrium particle distribution in synchrotron phase space for electron storage rings is discussed with respect to some localized constant wake function based on the Gaussian approximation. This mapping shows multi-periodic states as well as double bifurcation in dynamical states of the equilibrium bunch length. When moving around parameter space, the system shows a transition/bifurcation which is not always reversible. These results derived by mapping are confirmed by multiparticle tracking. (author)

  1. HIGH BIFURCATION OF THE BRACHIAL ARTERY - A COMMON VARIANT

    Directory of Open Access Journals (Sweden)

    Sesi

    2015-10-01

    Full Text Available 28 cadavers were dissected for variations in the bifurcation of brachial artery bilaterally {n=56} at the department of anatomy, Rangaraya Medical College, Kakinada, A.P. from 2010 to 2015 . Found variations during routine dissections for first year MBBS students. The findings have thrown light on the common as well as rare variants in the anatomy of brachial artery bifurcation and the course of radial and ulnar arteries in current study

  2. Delayed Feedback Control and Bifurcation Analysis of an Autonomy System

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    2013-01-01

    Full Text Available An autonomy system with time-delayed feedback is studied by using the theory of functional differential equation and Hassard’s method; the conditions on which zero equilibrium exists and Hopf bifurcation occurs are given, the qualities of the Hopf bifurcation are also studied. Finally, several numerical simulations are given; which indicate that when the delay passes through certain critical values, chaotic oscillation is converted into a stable state or a stable periodic orbit.

  3. Visual estimation versus different quantitative coronary angiography methods to assess lesion severity in bifurcation lesions.

    Science.gov (United States)

    Grundeken, Maik J; Collet, Carlos; Ishibashi, Yuki; Généreux, Philippe; Muramatsu, Takashi; LaSalle, Laura; Kaplan, Aaron V; Wykrzykowska, Joanna J; Morel, Marie-Angèle; Tijssen, Jan G; de Winter, Robbert J; Onuma, Yoshinobu; Leon, Martin B; Serruys, Patrick W

    2017-08-24

    To compare visual estimation with different quantitative coronary angiography (QCA) methods (single-vessel versus bifurcation software) to assess coronary bifurcation lesions. QCA has been developed to overcome the limitations of visual estimation. Conventional QCA however, developed in "straight vessels," has proved to be inaccurate in bifurcation lesions. Therefore, bifurcation QCA was developed. However, the impact of these different modalities on bifurcation lesion severity classification is yet unknown METHODS: From a randomized controlled trial investigating a novel bifurcation stent (Clinicaltrials.gov NCT01258972), patients with baseline assessment of lesion severity by means of visual estimation, single-vessel QCA, 2D bifurcation QCA and 3D bifurcation QCA were included. We included 113 bifurcations lesions in which all 5 modalities were assessed. The primary end-point was to evaluate how the different modalities affected the classification of bifurcation lesion severity and extent of disease. On visual estimation, 100% of lesions had side-branch diameter stenosis (%DS) >50%, whereas in 83% with single-vessel QCA, 27% with 2D bifurcation QCA and 26% with 3D bifurcation QCA a side-branch %DS >50% was found (P < 0.0001). With regard to the percentage of "true" bifurcation lesions, there was a significant difference between visual estimate (100%), single-vessel QCA (75%) and bifurcation QCA (17% with 2D bifurcation software and 13% with 3D bifurcation software, P < 0.0001). Our study showed that bifurcation lesion complexity was significantly affected when more advanced bifurcation QCA software were used. "True" bifurcation lesion rate was 100% on visual estimation, but as low as 13% when analyzed with dedicated bifurcation QCA software. © 2017 Wiley Periodicals, Inc.

  4. Nonenhanced hybridized arterial spin labeled magnetic resonance angiography of the extracranial carotid arteries using a fast low angle shot readout at 3 Tesla.

    Science.gov (United States)

    Koktzoglou, Ioannis; Walker, Matthew T; Meyer, Joel R; Murphy, Ian G; Edelman, Robert R

    2016-04-12

    To evaluate ungated nonenhanced hybridized arterial spin labeling (hASL) magnetic resonance angiography (MRA) of the extracranial carotid arteries using a fast low angle shot (FLASH) readout at 3 Tesla. In this retrospective, institutional review board-approved and HIPAA-compliant study, we evaluated the image quality (4-point scale) of nonenhanced hASL MRA using a FLASH readout with respect to contrast-enhanced MRA (CEMRA) in 37 patients presenting with neurologic symptoms. Two certified neuroradiologists independently evaluated 407 arterial segments (11 per patient) for image quality. The presence of vascular pathology was determined by consensus reading. Gwet's AC1 was used to assess inter-rater agreement in image quality scores, and image quality scores were correlated with age and body mass index. Objective measurements of arterial lumen area and sharpness in the carotid arteries were compared to values obtained with CEMRA. Comparisons were also made with conventional nonenhanced 2D time-of-flight (TOF) MRA. CEMRA provided the best image quality, while nonenhanced hASL FLASH MRA provided image quality that exceeded 2D TOF at the carotid bifurcation and in the internal and external carotid arteries. All nine vascular abnormalities of the carotid and intracranial arteries detected by CEMRA were depicted with hASL MRA, with no false positives. Inter-rater agreement of image quality scores was highest for CEMRA (AC1 = 0.87), followed by hASL (AC1 = 0.61) and TOF (AC1 = 0.43) (P < 0.001, all comparisons). With respect to CEMRA, agreement in cross-sectional lumen area was significantly better with hASL than TOF in the common carotid artery (intraclass correlation (ICC) = 0.90 versus 0.66; P < 0.05) and at the carotid bifurcation (ICC = 0.87 versus 0.54; P < 0.05). Nonenhanced hASL MRA provided superior arterial sharpness with respect to CEMRA and 2D TOF (P < 0.001). Although inferior to CEMRA in terms of image quality and inter

  5. Midazolam depresses carotid body chemoreceptor activity.

    Science.gov (United States)

    Kim, C; Shvarev, Y; Takeda, S; Sakamoto, A; Lindahl, S G E; Eriksson, L I

    2006-02-01

    Although the contribution of the gamma-aminobutyric acid (GABA) receptor system in peripheral chemosensation is unclear, immunohistochemistry has demonstrated the presence of GABA-ergic receptors in mammalian carotid bodies. We hypothesized that an activation of the carotid body GABA receptors would counteract the depolarizing effect of hypoxia. The carotid body with arterial supply and the carotid sinus nerve was removed en bloc from New Zealand White rabbits and placed in a perfusion chamber. The carotid body preparation was perfused via the cut common carotid artery with a modified Tyrode's solution at a rate of 3.5-4.5 ml/min with a constant pressure of 45 cmH2O. The carotid sinus nerve firing frequency (Hz) was recorded at two different oxygen tension levels during perfusion with midazolam of 1, 10 and 100 microg/l. The frequency was decreased by midazolam in a dose-dependent manner (n = 8). Firing frequencies (mean +/- SEM) at the low oxygen tension level decreased from 643.13 +/- 67.2 Hz in the control to 554.5 +/- 67.7 Hz (P = 0.054 vs. control), 509.01 +/- 100.5 Hz (P chemoreceptor activity in a dose-dependent manner.

  6. Carotid artery stenting vs carotid endarterectomy: meta-analysis and diversity-adjusted trial sequential analysis of randomized trials

    DEFF Research Database (Denmark)

    Bangalore, Sripal; Kumar, Sunil; Wetterslev, Jørn

    2011-01-01

    The role of carotid artery stenting (CAS) when compared with carotid endarterectomy (CEA) is controversial, with recent trials showing an increased risk of harm with CAS.......The role of carotid artery stenting (CAS) when compared with carotid endarterectomy (CEA) is controversial, with recent trials showing an increased risk of harm with CAS....

  7. Exploration of cervical carotid stenosis using helical CT angiography. A prospective trial on the detection of candidates for surgery in the Gujo area, Gifu

    Energy Technology Data Exchange (ETDEWEB)

    Yamakawa, Hiroyasu; Sumi, Yasuhiko [Sumi Hospital, Gifu (Japan); Kaku, Yasuhiko; Sakai, Noboru; Yamada, Hiromu

    1995-04-01

    To detect cervical carotid stenosis as a candidate for carotid endarterectomy (CEA), the authors attempted a prospective trial by exploring stenosis for one year in a rural district with a population of 20,000, employing helical CT angiography which apparently displayed three-dimensional reconstructed images of the carotid bifurcation. Thirty-three patients, 24 males and 9 females, with a mean age of 71.8 years, suffering from TIA, RIND or stroke were investigated for their carotid systems. The clinical symptoms of the patients were briefly as follows: motor weakness in 30 cases, dysarthria in 8 cases and aphasia in 4 cases; and 6 of 22 (27%) stroke cases had previously suffered an episode of TIA. The risk factors of the whole group of patients were hypertension in 13 cases, diabetes mellitus in 6, heart disease in 17, and hypercholesteremia in 4. Helical CT angiography was performed in 11 cases of TIA, 2 cases of RIND, and 16 cases of stroke. Only 3 cases of the TIA group and 3 cases of the stroke group were found to have extracranial carotid stenosis of more than 50%, which subsequently required conventional angiography. For the detection of stenosis, CT angiography was beneficial as well as conventional angiography. Finally, CEA was performed in 2 of 3 cases with severe carotid stonosis in the TIA group, while such cases in the stroke group were only observed. The above results meant that the occurrence of extracranial carotid stenosis was 6 out of 6,589 elderly inhabitants (over 60 years old), although the possible detection rate of candidates for CEA was 2 out of 20,000 population per year. (author).

  8. Turbulence intensity measurements using particle image velocimetry in diseased carotid artery models: effect of stenosis severity, plaque eccentricity, and ulceration.

    Science.gov (United States)

    Kefayati, Sarah; Holdsworth, David W; Poepping, Tamie L

    2014-01-03

    Clinical decision-making for the treatment of patients with diseased carotid artery is mainly based on the severity of the stenosis. However, stenosis severity alone is not a sensitive indicator, and other local factors for the assessment of stroke risk are required. Flow disturbance is of particular interest due to its proven association with increased thromboembolic activities. The objective of this study was to investigate the level of turbulence intensity (TI) with regards to certain geometrical features of the plaque - namely stenosis severity, eccentricity, and ulceration. A family of eight carotid-artery bifurcation models was examined using particle image velocimetry. Results showed a marked difference in turbulence intensity among these models; increasing degree of stenosis severity resulted in increased turbulence intensity, going from 0.12 m/s for mild stenosis to 0.37 m/s for severe stenosis (with concentric geometry). Moreover, independent of stenosis severity, eccentricity led to further elevations in turbulence intensity, increasing TI by 0.05-0.10 m/s over the counterpart concentric plaque. The presence of ulceration (in a 50% eccentric plaque) produced a larger portion of moderate turbulence intensity (~0.10 m/s) compared to the non-ulcerated model, more proximal to the bifurcation apex in the post-stenotic recirculation zone. The effect of plaque eccentricity and ulceration in enhancing the downstream turbulence has potential clinical implications for a more sensitive assessment of stroke risk beyond stenosis severity alone. © 2013 Elsevier Ltd. All rights reserved.

  9. Bifurcation magnetic resonance in films magnetized along hard magnetization axis

    Energy Technology Data Exchange (ETDEWEB)

    Vasilevskaya, Tatiana M., E-mail: t_vasilevs@mail.ru [Ulyanovsk State University, Leo Tolstoy 42, 432017 Ulyanovsk (Russian Federation); Sementsov, Dmitriy I.; Shutyi, Anatoliy M. [Ulyanovsk State University, Leo Tolstoy 42, 432017 Ulyanovsk (Russian Federation)

    2012-09-15

    We study low-frequency ferromagnetic resonance in a thin film magnetized along the hard magnetization axis performing an analysis of magnetization precession dynamics equations and numerical simulation. Two types of films are considered: polycrystalline uniaxial films and single-crystal films with cubic magnetic anisotropy. An additional (bifurcation) resonance initiated by the bistability, i.e. appearance of two closely spaced equilibrium magnetization states is registered. The modification of dynamic modes provoked by variation of the frequency, amplitude, and magnetic bias value of the ac field is studied. Both steady and chaotic magnetization precession modes are registered in the bifurcation resonance range. - Highlights: Black-Right-Pointing-Pointer An additional bifurcation resonance arises in a case of a thin film magnetized along HMA. Black-Right-Pointing-Pointer Bifurcation resonance occurs due to the presence of two closely spaced equilibrium magnetization states. Black-Right-Pointing-Pointer Both regular and chaotic precession modes are realized within bifurcation resonance range. Black-Right-Pointing-Pointer Appearance of dynamic bistability is typical for bifurcation resonance.

  10. Editorial: at the bifurcation of the last frontiers.

    Science.gov (United States)

    Nguyen, Thach; Chen, Shao Liang; Xu, Bo; Kwan, Tak; Nguyen, Katrina; Nanjundappa, Aravinda; Van Ho, Bao; Gao, Run-Lin

    2010-08-01

    The concept of coronary angioplasty percutaneous coronary intervention (PCI) was pioneered by Andreas Gruntzig. Since then, several modifications, innovative devices, techniques, and advances have revolutionized the practice of interventional cardiology. Coronary bifurcation and chronic total occlusion are the last two frontiers that continue to challenge the skills of the interventional cardiologists. Proceedings of the second Bifurcation Summit held from November 26 to 28, 2009 in Nanjing, China are published in this symposium. In a general review, the state of the art in management of bifurcation lesion is summarized in the statement of the "Bifurcation Club in KOKURA." A new-presented concept was the "extension distance" between the main vessel and the sidebranch ostia and its association with restenosis. The results of two studies on shear stress (SS) after PCI showed that contradictory lower SS after stenting was associated with lower in-stent restenosis. There was better fractional flow reserve after double kissing crush technique than provisional one-stent technique. There was also lower rate of stent thrombosis after bifurcation stenting with excellent final angiographic results. In a negative note, the SYNTAX score had no predictive values on trifurcated left main stenting. In summary, different aspects of percutaneous management for bifurcated lesion are described seen from different perspectives and evidenced by novel techniques and strategies.

  11. Attractors, bifurcations, & chaos nonlinear phenomena in economics

    CERN Document Server

    Puu, Tönu

    2003-01-01

    The present book relies on various editions of my earlier book "Nonlinear Economic Dynamics", first published in 1989 in the Springer series "Lecture Notes in Economics and Mathematical Systems", and republished in three more, successively revised and expanded editions, as a Springer monograph, in 1991, 1993, and 1997, and in a Russian translation as "Nelineynaia Economicheskaia Dinamica". The first three editions were focused on applications. The last was differ­ ent, as it also included some chapters with mathematical background mate­ rial -ordinary differential equations and iterated maps -so as to make the book self-contained and suitable as a textbook for economics students of dynamical systems. To the same pedagogical purpose, the number of illus­ trations were expanded. The book published in 2000, with the title "A ttractors, Bifurcations, and Chaos -Nonlinear Phenomena in Economics", was so much changed, that the author felt it reasonable to give it a new title. There were two new math­ ematics ch...

  12. Association of mitochondrial genetic variation with carotid atherosclerosis.

    Directory of Open Access Journals (Sweden)

    Igor A Sobenin

    Full Text Available In human pathology, several diseases are associated with somatic mutations in the mitochondrial genome (mtDNA. Even though mitochondrial dysfunction leads to increased oxidative stress, the role of mitochondrial mutations in atherosclerosis has not received much attention so far. In this study we analyzed the association of mitochondrial genetic variation with the severity of carotid atherosclerosis, as assessed by carotid intima-media thickness (cIMT and the presence of coronary heart disease (CHD in 190 subjects from Moscow, Russia, a population with high CHD occurrence. cIMT was measured by high-resolution B-mode ultrasonography and mtDNA heteroplasmies by a pyrosequencing-based method. We found that heteroplasmies for several mutations in the mtDNA in leukocytes, including C3256T, T3336C, G12315A, G13513A, G14459A, G14846A, and G15059A mutations, were significantly (p<0.001 associated with both the severity of carotid atherosclerosis and the presence of CHD. These findings indicate that somatic mitochondrial mutations have a role in the development of atherosclerosis.

  13. A RARE CASE OF ORIGIN OF THE SUPERIOR THYROID ARTERY FROM THE RIGHT COMMON CAROTID ARTERY

    Directory of Open Access Journals (Sweden)

    Y MOHAMADI

    1982-05-01

    Full Text Available Recent l y i n a clas sroom d is sect i on we f ounu an anoma l ou s superior thyroid artery in a 60-year -ol d man . The arte ry originated f rom t he common carotid 31 mm p rox imal t o its bifurcation . Rega r d i ng t o the s ex , the s i de and p lace o f o r i g i n , this could be a unique case , suggesting a need for more awarene s s o f any unpredictable anomal y whi ch may be s een i n th i s a r ter y t o avo id serious problems during s ur ger y on the thyroid gland .

  14. Carotid artery stenosis after neck radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Shimamura, Munehisa; Hashimoto, Yoichiro; Kasuya, Junji; Terasaki, Tadashi [Kumamoto City Hospital (Japan); Uchino, Makoto

    2000-02-01

    Carotid artery stenosis sometimes occurs after cervical radiotherapy. We report a 70-year-old woman with a history of radiotherapy for thyroid cancer at the age of 28 years. She had no signs and symptoms except the skin lesion at the irradiation site. Duplex ultrasonography revealed heterogeneous plaques showing 50% stenosis of bilateral common carotid arteries. Those lesions were observed within segment of irradiation, where atheromatous plaque usually seldom occurs. These indicated that the carotid stenosis was induced by radiotherapy. Although the efficacy of antiplatelet therapy for radiation-induced plaque is not clear, the plaques remained unchanged for 4 years in spite of aspirin administration. (author)

  15. General principles of carotid Doppler ultrasonography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Whal [Dept. of Radiology, Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2014-03-15

    Carotid Doppler ultrasonography is a popular tool for evaluating atherosclerosis of the carotid artery. Its two-dimensional gray scale can be used for measuring the intima-media thickness, which is very good biomarker for atherosclerosis and can aid in plaque characterization. The plaque morphology is related to the risk of stroke. The ulceration of plaque is also known as one of the strong predictors of future embolic event risk. Color Doppler ultrasonography and pulse Doppler ultrasonography have been used for detecting carotid artery stenosis. Doppler ultrasonography has unique physical properties. The operator should be familiar with the physics and other parameters of Doppler ultrasonography to perform optimal Doppler ultrasonography studies.

  16. Treatment of a Coronary Bifurcation Lesion Using One Dedicated Sirolimus Eluting Bifurcation Stent in Combination with a Bioresorbable Vascular Scaffold: A Novel Option for Coronary Bifurcation Approach

    Directory of Open Access Journals (Sweden)

    Javier Benezet

    2016-01-01

    Full Text Available We present a complex bifurcation lesion treated with a new two-stent strategy combining a dedicated sirolimus eluting bifurcation stent, BiOSS Lim, with a bioresorbable vascular scaffold (BVS. The advantages of this strategy compared with the conventional two-stent approach are as follows: the dedicated stent protects the carina from being damaged, the large cell at the middle zone of the BiOSS Lim gives possibility to enter easily into the side branch (SB with any standard size conventional device, and, finally, the additional use of BVS in the SB could have a long-term benefit in terms of restenosis.

  17. Photoperiodic and circadian bifurcation theories of depression and mania.

    Science.gov (United States)

    Kripke, Daniel F; Elliott, Jeffrey A; Welsh, David K; Youngstedt, Shawn D

    2015-01-01

    Seasonal effects on mood have been observed throughout much of human history.  Seasonal changes in animals and plants are largely mediated through the changing photoperiod (i.e., the photophase or duration of daylight).  We review that in mammals, daylight specifically regulates SCN (suprachiasmatic nucleus) circadian organization and its control of melatonin secretion.  The timing of melatonin secretion interacts with gene transcription in the pituitary pars tuberalis to modulate production of TSH (thyrotropin), hypothalamic T3 (triiodothyronine), and tuberalin peptides which modulate pituitary production of regulatory gonadotropins and other hormones.  Pituitary hormones largely mediate seasonal physiologic and behavioral variations.  As a result of long winter nights or inadequate illumination, we propose that delayed morning offset of nocturnal melatonin secretion, suppressing pars tuberalis function, could be the main cause for winter depression and even cause depressions at other times of year.  Irregularities of circadian sleep timing and thyroid homeostasis contribute to depression.  Bright light and sleep restriction are antidepressant and conversely, sometimes trigger mania.  We propose that internal desynchronization or bifurcation of SCN circadian rhythms may underlie rapid-cycling manic-depressive disorders and perhaps most mania.  Much further research will be needed to add substance to these theories.

  18. Why carotid endarterectomy is method of choice in treatment of carotid stenosis

    Directory of Open Access Journals (Sweden)

    Radak Đorđe

    2008-01-01

    Full Text Available Procedures used in treatment of carotid stenosis are endarterectomy, PTA with stent implantation, resection with graft interposition and by-pass procedure. Segmental lesions are found more often and treated by the first two mentioned procedures. In case of longer lesions and extension to the greater part of the common carotid artery, the other two procedures are performed. For the past few years, the main dilemma has been whether to perform carotid endarterectomy or PTA with stent implantation. Both early and long-term results speak in favour of carotid endarterectomy, regardless of an increased number of PTA and carotid stenting. At the same time, PTA and carotid stenting are more expensive procedures. Both methods have their defined and important roles in treatment of segmental occlusive carotid lesions. Severe cardiac, pulmonary and renal conditions, which increase the risk of general anaesthesia, are not an absolute indication for PTA and stenting, since endarterectomy can be done in regional anaesthesia. Main indications for PTA with stent implantation are: surgically inaccessible lesions (at or above C2; or subclavian; radiation- induced carotid stenosis; prior ipsilateral radical neck dissection; prior carotid endarterectomy (restenosis.

  19. Carotid angioplasty with stenting for chronic internal carotid artery occlusion: technical note

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Nozomu; Tanasawa, Toshihiko; Okada, Takeshi; Endo, Otone; Yamamoto, Naohito [Kainan Hospital Aichi Prefectural Welfare Federation of Agricultural Cooperatives, Department of Neurosurgery, Aichi (Japan); Miyachi, Shigeru; Hattori, Kenichi [Nagoya University Graduate School of Medicine, Department of Neurosurgery, Nagoya (Japan)

    2006-11-15

    Carotid angioplasty with stenting (CAS) is becoming accepted as an effective and reliable treatment option for severe carotid artery stenosis. However, it is rarely applied for carotid occlusion, especially in its chronic stage. We report our experience of CAS for chronic internal carotid artery occlusion representing compromised cerebral blood flow using various protection methods. A 77-year-old woman, who was already diagnosed with severe left internal carotid artery stenosis, suddenly had right hemiparesis and aphasia. At that time, she was treated conservatively because her neurological status was quite good, in spite of left carotid artery occlusion. Her symptoms improved in the short term, except slight aphasia, but deteriorated again 18 days from the onset, and magnetic resonance imaging (MRI) showed new ischemic lesions. CAS was then performed for the occluded carotid artery on the 23rd day from the first onset. Using the proximal protection technique, the occluded lesion was crossed carefully with a microguidewire. Stents were also placed successfully with the distal protection technique. The occluded carotid artery was completely recanalized without any unfavorable events or neurological deterioration. In this patient, CAS was successfully to treat chronic carotid artery occlusion. These procedures and techniques are reviewed and discussed. (orig.)

  20. Obesity and carotid artery remodeling

    DEFF Research Database (Denmark)

    Kozakova, M; Palombo, C; Morizzo, C

    2015-01-01

    BACKGROUND/OBJECTIVE: The present study tested the hypothesis that obesity-related changes in carotid intima-media thickness (IMT) might represent not only preclinical atherosclerosis but an adaptive remodeling meant to preserve circumferential wall stress (CWS) in altered hemodynamic conditions...... and CCA LD (266 healthy subjects with wide range of body weight (24-159 kg)); (B) longitudinal associations between CCA LD and 3-year IMT progression rate (ΔIMT; 571 healthy non-obese subjects without increased cardiovascular (CV) risk); (C) the impact of obesity on CCA geometry and CWS (88 obese subjects...... without CV complications and 88 non-obese subjects matched for gender and age). RESULTS: CCA LD was independently associated with SV that was determined by body size. In the longitudinal study, baseline LD was an independent determinant of ΔIMT, and ΔIMT of subjects in the highest LD quartile...

  1. Ophthalmic masquerades of the atherosclerotic carotids

    Directory of Open Access Journals (Sweden)

    Anupriya Arthur

    2014-01-01

    Full Text Available Patients with carotid atherosclerosis can present with ophthalmic symptoms. These symptoms and signs can be due to retinal emboli, hypoperfusion of the retina and choroid, opening up of collateral channels, or chronic hypoperfusion of the globe (ocular ischemic syndrome. These pathological mechanisms can produce many interesting signs and a careful history can bring out important past symptoms pointing toward the carotid as the source of the patient′s presenting symptom. Such patients are at high risk for an ischemic stroke, especially in the subsequent few days following their first acute symptom. It is important for clinicians to be familiar with these ophthalmic symptoms and signs caused by carotid atherosclerosis for making an early diagnosis and to take appropriate measures to prevent a stroke. This review elaborates the clinical features, importance, and implications of various ophthalmic symptoms and signs resulting from atherosclerotic carotid artery disease.

  2. Defective cerebrovascular autoregulation after carotid endarterectomy

    DEFF Research Database (Denmark)

    Jørgensen, L G; Schroeder, T V

    1993-01-01

    Correction of high grade carotid artery stenosis may result in cerebral hyperperfusion because of defective vascular autoregulation. Thus, transcranial Doppler was used to determine mean arterial flow velocity (Vmean) of the middle cerebral artery in 95 patients before and after carotid endartere......Correction of high grade carotid artery stenosis may result in cerebral hyperperfusion because of defective vascular autoregulation. Thus, transcranial Doppler was used to determine mean arterial flow velocity (Vmean) of the middle cerebral artery in 95 patients before and after carotid......th postoperative day, respectively. The mean pressure difference across the stenosis was 31 (0-63) mmHg in the symptomatic group (n = 18) as opposed to only 10 (0-60) mmHg in the asymptomatic group (n = 77) (p surgery, ipsilateral Vmean increased to 177...

  3. Fusiform aneurysm model in rabbit carotid artery.

    Science.gov (United States)

    Reinald, Nicoleta; Fournier, Benjamin; Naveau, Adrien; Couty, Ludovic; Lemitre, Mathilde; Seguier, Sylvie; Coulomb, Bernard; Gogly, Bruno; Lafont, Antoine; Durand, Eric

    2010-01-01

    To develop a reproducible and accessible model of elastase-induced fusiform aneurysm in carotid rabbit arteries. Elastase, at a concentration of 1-30 U, was incubated into the lumen of carotid rabbit arteries. Four weeks later, angiography, histomorphometry, immunohistochemistry and zymography were performed. The optimal concentration of elastase in this model was 3 U according to the balance between mortality and thrombosis rates. Indeed, at 3 U, external carotid diameter increased from 1.9 +/- 0.1 to 3.1 +/- 0.4 mm (p < 0.0001) associated with degradation of elastic fibers, matrix metalloproteinase-9 secretion, apoptosis and macrophage infiltration. Our study underlines that abdominal aortic aneurysm can be reliably duplicated in an elastase-induced aneurysm in carotid artery, a much more accessible vessel. Copyright 2009 S. Karger AG, Basel.

  4. PLACD-7T Study: Atherosclerotic Carotid Plaque Components Correlated with Cerebral Damage at 7 Tesla Magnetic Resonance Imaging.

    Science.gov (United States)

    den Hartog, A G; Bovens, S M; Koning, W; Hendrikse, J; Pasterkamp, G; Moll, F L; de Borst, G J

    2011-02-01

    In patients with carotid artery stenosis histological plaque composition is associated with plaque stability and with presenting symptomatology. Preferentially, plaque vulnerability should be taken into account in pre-operative work-up of patients with severe carotid artery stenosis. However, currently no appropriate and conclusive (non-) invasive technique to differentiate between the high and low risk carotid artery plaque in vivo is available. We propose that 7 Tesla human high resolution MRI scanning will visualize carotid plaque characteristics more precisely and will enable correlation of these specific components with cerebral damage. The aim of the PlaCD-7T study is 1: to correlate 7T imaging with carotid plaque histology (gold standard); and 2: to correlate plaque characteristics with cerebral damage ((clinically silent) cerebral (micro) infarcts or bleeds) on 7 Tesla high resolution (HR) MRI. We propose a single center prospective study for either symptomatic or asymptomatic patients with haemodynamic significant (70%) stenosis of at least one of the carotid arteries. The Athero-Express (AE) biobank histological analysis will be derived according to standard protocol. Patients included in the AE and our prospective study will undergo a pre-operative 7 Tesla HR-MRI scan of both the head and neck area. We hypothesize that the 7 Tesla MRI scanner will allow early identification of high risk carotid plaques being associated with micro infarcted cerebral areas, and will thus be able to identify patients with a high risk of periprocedural stroke, by identification of surrogate measures of increased cardiovascular risk.

  5. The surgical challenge of carotid artery and Fallopian canal dehiscence in chronic ear disease: a pitfall for endoscopic approach.

    Science.gov (United States)

    Pauna, H F; Monsanto, R C; Schachern, P A; Costa, S S; Kwon, G; Paparella, M M; Cureoglu, S

    2017-04-01

    Endoscopic procedures are becoming common in middle ear surgery. Inflammation due to chronic ear disease can cause bony erosion of the carotid artery and Fallopian canals, making them more vulnerable during surgery. The objective of this study was to determine whether or not chronic ear disease increases dehiscence of the carotid artery and Fallopian canals. Comparative human temporal bone study. Otopathology laboratory. We selected 78 temporal bones from 55 deceased donors with chronic otitis media or cholesteatoma and then compared those two groups with a control group of 27 temporal bones from 19 deceased donors with no middle ear disease. We analysed the middle ear, carotid artery canal and Fallopian canal, looking for signs of dehiscence of its bony coverage, using light microscopy. We found an increased incidence in dehiscence of the carotid artery and Fallopian canals in temporal bones with chronic middle ear disease. The size of the carotid artery canal dehiscence was larger in the middle ear-diseased groups, and its bony coverage, when present, was also thinner compared to the control group. Dehiscence of the carotid artery canal was more frequently located closer to the promontory. The incidence of Fallopian canal dehiscence was significantly higher in temporal bones from donors older than 18 years with chronic middle ear disease. The increased incidence of the carotid artery and Fallopian canal dehiscence in temporal bones with chronic middle ear disease elevates the risk of adverse events during middle ear surgery. © 2016 John Wiley & Sons Ltd.

  6. Mammalian evolution may not be strictly bifurcating.

    Science.gov (United States)

    Hallström, Björn M; Janke, Axel

    2010-12-01

    The massive amount of genomic sequence data that is now available for analyzing evolutionary relationships among 31 placental mammals reduces the stochastic error in phylogenetic analyses to virtually zero. One would expect that this would make it possible to finally resolve controversial branches in the placental mammalian tree. We analyzed a 2,863,797 nucleotide-long alignment (3,364 genes) from 31 placental mammals for reconstructing their evolution. Most placental mammalian relationships were resolved, and a consensus of their evolution is emerging. However, certain branches remain difficult or virtually impossible to resolve. These branches are characterized by short divergence times in the order of 1-4 million years. Computer simulations based on parameters from the real data show that as little as about 12,500 amino acid sites could be sufficient to confidently resolve short branches as old as about 90 million years ago (Ma). Thus, the amount of sequence data should no longer be a limiting factor in resolving the relationships among placental mammals. The timing of the early radiation of placental mammals coincides with a period of climate warming some 100-80 Ma and with continental fragmentation. These global processes may have triggered the rapid diversification of placental mammals. However, the rapid radiations of certain mammalian groups complicate phylogenetic analyses, possibly due to incomplete lineage sorting and introgression. These speciation-related processes led to a mosaic genome and conflicting phylogenetic signals. Split network methods are ideal for visualizing these problematic branches and can therefore depict data conflict and possibly the true evolutionary history better than strictly bifurcating trees. Given the timing of tectonics, of placental mammalian divergences, and the fossil record, a Laurasian rather than Gondwanan origin of placental mammals seems the most parsimonious explanation.

  7. Bifurcations of a periodically forced microbial continuous culture model with restrained growth rate

    Science.gov (United States)

    Ren, Jingli; Yuan, Qigang

    2017-08-01

    A three dimensional microbial continuous culture model with a restrained microbial growth rate is studied in this paper. Two types of dilution rates are considered to investigate the dynamic behaviors of the model. For the unforced system, fold bifurcation and Hopf bifurcation are detected, and numerical simulations reveal that the system undergoes degenerate Hopf bifurcation. When the system is periodically forced, bifurcation diagrams for periodic solutions of period-one and period-two are given by researching the Poincaré map, corresponding to different bifurcation cases in the unforced system. Stable and unstable quasiperiodic solutions are obtained by Neimark-Sacker bifurcation with different parameter values. Periodic solutions of various periods can occur or disappear and even change their stability, when the Poincaré map of the forced system undergoes Neimark-Sacker bifurcation, flip bifurcation, and fold bifurcation. Chaotic attractors generated by a cascade of period doublings and some phase portraits are given at last.

  8. Correlation of carotid blood flow and corrected carotid flow time with invasive cardiac output measurements.

    Science.gov (United States)

    Ma, Irene W Y; Caplin, Joshua D; Azad, Aftab; Wilson, Christina; Fifer, Michael A; Bagchi, Aranya; Liteplo, Andrew S; Noble, Vicki E

    2017-12-01

    Non-invasive measures that can accurately estimate cardiac output may help identify volume-responsive patients. This study seeks to compare two non-invasive measures (corrected carotid flow time and carotid blood flow) and their correlations with invasive reference measurements of cardiac output. Consenting adult patients (n = 51) at Massachusetts General Hospital cardiac catheterization laboratory undergoing right heart catheterization between February and April 2016 were included. Carotid ultrasound images were obtained concurrently with cardiac output measurements, obtained by the thermodilution method in the absence of severe tricuspid regurgitation and by the Fick oxygen method otherwise. Corrected carotid flow time was calculated as systole time/√cycle time. Carotid blood flow was calculated as π × (carotid diameter)2/4 × velocity time integral × heart rate. Measurements were obtained using a single carotid waveform and an average of three carotid waveforms for both measures. Single waveform measurements of corrected flow time did not correlate with cardiac output (ρ = 0.25, 95% CI -0.03 to 0.49, p = 0.08), but an average of three waveforms correlated significantly, although weakly (ρ = 0.29, 95% CI 0.02-0.53, p = 0.046). Carotid blood flow measurements correlated moderately with cardiac output regardless of if single waveform or an average of three waveforms were used: ρ = 0.44, 95% CI 0.18-0.63, p = 0.004, and ρ = 0.41, 95% CI 0.16-0.62, p = 0.004, respectively. Carotid blood flow may be a better marker of cardiac output and less subject to measurements issues than corrected carotid flow time.

  9. Derivação carótido-carotídea por via retrofaríngea: seguimento tardio Retropharyngeal carotid-carotid crossover bypass: late follow-up

    Directory of Open Access Journals (Sweden)

    Newton Roech Aerts

    2005-01-01

    Full Text Available Existem diversas opções para o tratamento da doença oclusiva dos troncos supra-aórticos, de acordo com a apresentação clínica e a localização das lesões arteriais. As abordagens cervicais são aceitas como alternativas de baixa morbimortalidade, com elevada perviedade em longo prazo. Os autores relatam um caso tratado com sucesso através de derivação carótido-carotídea cruzada por via retrofaríngea associada à endarterectomia da bifurcação carotídea. São discutidos também os aspectos clínicos e as opções cirúrgicas ou endovasculares para o melhor tratamento desses pacientes.A variety of therapeutic options are available to manage the disease of supra-aortic trunks based on clinical presentations and anatomic location of the arterial lesions. The cervical approach is accepted as having low morbidity and mortality with elevated long-term patency. The authors report a successfully treated case of carotid-carotid crossover bypass by the retropharyngeal route associated with endarterectomy of carotid bifurcation. We also discuss clinical aspects, and surgical or endovascular options for the best treatment of these patients.

  10. Bifurcation of an Orbit Homoclinic to a Hyperbolic Saddle of a Vector Field in R4

    Directory of Open Access Journals (Sweden)

    Tiansi Zhang

    2015-01-01

    Full Text Available We perform a bifurcation analysis of an orbit homoclinic to a hyperbolic saddle of a vector field in R4. We give an expression of the gap between returning points in a transverse section by renormalizing system, through which we find the existence of homoclinic-doubling bifurcation in the case 1+α>β>ν. Meanwhile, after reparametrizing the parameter, a periodic-doubling bifurcation appears and may be close to a saddle-node bifurcation, if the parameter is varied. These scenarios correspond to the occurrence of chaos. Based on our analysis, bifurcation diagrams of these bifurcations are depicted.

  11. Local intra-arterial thrombolysis in the carotid territory: does recanalization depend on the thromboembolus type?

    Energy Technology Data Exchange (ETDEWEB)

    Urbach, H.; Wilhelm, K.; Flacke, S.; Schild, H.H. [Department of Radiology/Neuroradiology, University of Bonn, Sigmund Freud Strasse 25, 53105 Bonn (Germany); Hartmann, A.; Pohl, C.; Klockgether, T. [Department of Neurology, University of Bonn, Sigmund Freud Strasse 25, 53105 Bonn (Germany); Omran, H. [Department of Cardiology, University of Bonn, Sigmund Freud Strasse 25, 53105 Bonn (Germany)

    2002-08-01

    Little is known about whether recanalization of carotid territory occlusions by local intra-arterial thrombolysis (LIT) depends on the type of the occluding thromboembolus. We retrospectively analysed the records of 62 patients with thromboembolic occlusions of the intracranial internal carotid artery (ICA) bifurcation or the middle cerebral artery who were undergoing LIT with urokinase within 6 h of symptom onset. We determined the influence of thromboembolus type (according to the TOAST criteria), thromboembolus location, leptomeningeal collaterals, time interval from onset of symptoms to onset of thrombolysis, and patient's age on recanalization. The thromboembolus type was atherosclerotic in six patients, cardioembolic in 29, of other determined etiology in four, and of undetermined etiology in 23 patients. Thirty-three (53%) thromboembolic occlusions were recanalized. The thromboembolus location but not the TOAST stroke type nor other parameters affected recanalization. In the TOAST group of patients with cardioembolic occlusions recanalization occurred significantly less frequently when transoesophageal echocardiography showed cardiac thrombus. The present study underlines the thromboembolus location as being the most important parameter affecting recanalization. The fact that thromboembolic occlusions originating from cardiac thrombi had a lower likelihood of being resolved by thrombolysis indicates the thromboembolus type as another parameter affecting recanalization. (orig.)

  12. Ability of the carotid duplex scan to predict stenosis, symptoms, and plaque structure.

    Science.gov (United States)

    Hill, S L; Donato, A T

    1994-11-01

    The duplex scan with its improved technology has allowed clinicians to visualize noninvasively the carotid bifurcation. We investigated whether the duplex scan, with its ability to visualize plaque structure, can reliably predict the major components of different plaques seen in pathologic studies. Furthermore, we studied whether it could correlate these findings with the presenting symptoms of patients and predict which patients would benefit from early endarterectomy. We performed a retrospective study of 84 patients during a 43-month period. The arteriogram, duplex scans, symptoms, and pathologic examination of the carotid atheroma in each patient were reviewed. The specimens were divided into three categories depending on the major component found in pathologic studies. One group consisted of calcific plaques, another was predominantly fibrosis and cholesterol, and the third was plaques with intramural hemorrhage. The angiograms and duplex scans were separately interpreted. Patients with symptoms (81%) were divided into those with amaurosis fugax (19%), transient ischemic attacks (58%), and cerebral vascular accidents (3%). The agreement between duplex scan findings and arteriograms concerning the percent stenosis was 95%. There was no correlation, however, between the presence or type of symptoms and the plaque structure as seen in pathologic studies or on the duplex scan. At this stage of technology the duplex scan is most reliable in detecting hemodynamically significant lesions. Its ability to predict symptoms or findings at surgery and possibly to alter treatment is at best limited.

  13. Numerical Investigation of Pulsatile Blood Flow in a Bifurcation Model with a Non-Planar Branch: The Effect of Different Bifurcation Angles and Non-Planar Branch

    Directory of Open Access Journals (Sweden)

    Omid Arjmandi-Tash

    2012-12-01

    Full Text Available Introduction: Atherosclerosis is a focal disease that susceptibly forms near bifurcations, anastomotic joints, side branches, and curved vessels along the arterial tree. In this study, pulsatile blood flow in a bifurcation model with a non-planar branch is investigated. Methods: Wall shear stress (WSS distributions along generating lines on vessels for different bifurcation angles are calculated during the pulse cycle. Results: The WSS at the outer side of the bifurcation plane vanishes especially for higher bifurcation angles but by increasing the bifurcation angle low WSS region squeezes. At the systolic phase there is a high possibility of formation of a separation region at the outer side of bifurcation plane for all the cases. WSS peaks exist on the inner side of bifurcation plane near the entry section of daughter vessels and these peaks drop as bifurcation angle is increased. Conclusion: It was found that non-planarity of the daughter vessel lowers the minimum WSS at the outer side of the bifurcation and increases the maximum WSS at the inner side. So it seems that the formation of atherosclerotic plaques at bifurcation region in direction of non-planar daughter vessel is more risky.

  14. The relation of carotid calcium volume with carotid artery stenosis in symptomatic patients

    NARCIS (Netherlands)

    Marquering, H. A.; Majoie, C. B. L. M.; Smagge, L.; Kurvers, A. G.; Gratama van Andel, H. A.; van den Berg, R.; Nederkoorn, P. J.

    2011-01-01

    Recent research showed a strong correlation of calcium volume scores with degree of stenosis, suggesting that calcium volume could be used in the diagnosis of carotid artery stenosis. We investigated the accuracy of the use of calcium volume scores to diagnose carotid artery stenosis in our target

  15. Internal carotid artery rupture caused by carotid shunt insertion.

    Science.gov (United States)

    Illuminati, Giulio; Caliò, Francesco G; Pizzardi, Giulia; Vietri, Francesco

    2015-01-01

    Shunting is a well-accepted method of maintaining cerebral perfusion during carotid endarterectomy (CEA). Nonetheless, shunt insertion may lead to complications including arterial dissection, embolization, and thrombosis. We present a complication of shunt insertion consisting of arterial wall rupture, not reported previously. A 78-year-old woman underwent CEA combined with coronary artery bypass grafting (CABG). At the time of shunt insertion an arterial rupture at the distal tip of the shunt was detected and was repaired via a small saphenous vein patch. Eversion CEA and subsequent CABG completed the procedure whose postoperative course was uneventful. Shunting during combined CEA-CABG may be advisable to assure cerebral protection from possible hypoperfusion due to potential hemodynamic instability of patients with severe coronary artery disease. Awareness and prompt management of possible shunt-related complications, including the newly reported one, may contribute to limiting their harmful effect. Arterial wall rupture is a possible, previously not reported, shunt-related complication to be aware of when performing CEA. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Assessment of hemodynamic changes near carotid atherosclerotic plaques by using magnetic resonance imaging and computational fluid dynamics

    Directory of Open Access Journals (Sweden)

    Li-na JING

    2014-07-01

    Full Text Available Objective To establish a platform by using carotid MRI and computational fluid dynamics (CFD to assess hemodynamic changes around carotid atherosclerotic plaques.  Methods Thirteen patients with carotid atherosclerosis were recruited in this study. Six volunteers were regarded as normal controls. All the patients and volunteers underwent carotid MRI and contrast-enhanced magnetic resonance angiography (CEMRA. Carotid MRI was used to visualize the plaque structures and components. All plaques were divided into different types according to plaque components. CEMRA images were used to obtain three-dimensional (3D models of carotid bifurcations, whose boundary conditions were specified using CFD front-end software, and then the mesh file of the 3D models were obtained to import to CFD software to visualize hemodynamic maps, including wall shear stress (WSS, static pressure and blood velocity.  Results Fifteen diseased internal carotid arteries (ICAs were assessed. According to the MRI appearance of the plaques, the types of these plaques were from Ⅳ-Ⅴ to Ⅷ. All of these were vulnerable plaques which caused irregular stenosis of ICAs. The WSS, static pressure and blood velocity were (79.86 ± 57.83 Pa, (-7586.81 ± 9313.83 Pa, (2.76±1.81 m/s, respectively in the diseased ICAs group and (2.52 ± 0.58 Pa, (-71.65 ± 30.89 Pa, (0.21 ± 0.06 m/s, respectively in the normal control group. In the diseased ICAs group WSS was elevated heterogenously and static pressure was decreased heterogenously near the plaques. The blood velocity near the plaques was increased but still streamlined. Statistical significant differences were shown for WSS, static pressure and blood velocity between 2 groups (P = 0.000, for all.  Conclusions The platform combining MRI and CFD can be used to analyze the plaque structures and fluid dynamic change near the plaques, suggesting hemodynamics plays an important role in the plaque progression and vulnerability. doi: 10

  17. Carotid endarterectomy in patients with occlusion of the contralateral carotid artery. Perioperative risk and late results

    DEFF Research Database (Denmark)

    Sillesen, H; Schroeder, T; Rasmussen, L

    1987-01-01

    Recent reports on the outcome of carotid endarterectomy in patients with contralateral occlusion have been conflicting. Therefore, we reviewed 51 cases identified, among 675 consecutive carotid endarterectomies. A perioperative mortality of 2% and a permanent morbidity rate of 16% was observed...... severe strokes when compared to patients with only minor reduction in CPP. In addition, the internal carotid artery blood flow following endarterectomy was significantly higher in the low pressure group (P less than 0.02). No patients were lost during follow-up, for a mean of 34 months. The cumulative....... Compared with a complication rate of about 5% previously reported from this institution, this clearly indicates contralateral carotid occlusion as a major risk factor in carotid surgery. Though not statistically significant, patients with severely reduced cerebral perfusion pressure (CPP) had suffered more...

  18. Bifurcated-bifurcated aneurysm repair is a novel technique to repair infrarenal aortic aneurysms in the setting of iliac aneurysms.

    Science.gov (United States)

    Shin, Susanna Hewon; Starnes, Benjamin Ware

    2017-11-01

    Up to 40% of abdominal aortic aneurysms (AAAs) have coexistent iliac artery aneurysms (IAAs). In the past, successful endovascular repair required internal iliac artery (IIA) embolization, which can lead to pelvic or buttock ischemia. This study describes a technique that uses a readily available solution with a minimally altered off-the-shelf bifurcated graft in the IAA to maintain IIA perfusion. From August 2009 to May 2015, 14 patients with AAAs and coexisting IAAs underwent repair with a bifurcated-bifurcated approach. A 22-mm or 24-mm bifurcated main body device was used in the IAA with extension of the "contralateral" limb into the IIA. Intraoperative details including operative time, fluoroscopy time, and contrast agent use were recorded. Outcome measures assessed were operative technical success and a composite outcome measure of IIA patency, freedom from reintervention, and clinically significant endoleak at 1 year. Fourteen patients underwent bifurcated-bifurcated repair during the study period. Technical success was achieved in 93% of patients, with successful treatment of the AAA and IAA and preservation of flow to at least one IIA. The procedure was performed with a completely percutaneous bilateral femoral approach in 92% of patients. Three patients had a type II endoleak on initial follow-up imaging, but none were clinically significant. There were no cases of bowel ischemia or erectile dysfunction. One patient had buttock claudication ipsilateral to IIA coil embolization (contralateral to bifurcated iliac repair and preserved IIA) that resolved by 6-month follow-up. Two patients required reinterventions. One patient presented to his first follow-up visit on postoperative day 25 with thrombosis of the right external iliac limb ipsilateral to the bifurcated iliac repair, which was successfully treated with thrombectomy and stenting of the limb. This same patient presented at 83 months with growth of the preserved IIA to 3.9 cm and underwent coil

  19. Numerical bifurcation analysis of a class of nonlinear renewal equations

    Directory of Open Access Journals (Sweden)

    Dimitri Breda

    2016-09-01

    Full Text Available We show, by way of an example, that numerical bifurcation tools for ODE yield reliable bifurcation diagrams when applied to the pseudospectral approximation of a one-parameter family of nonlinear renewal equations. The example resembles logistic- and Ricker-type population equations and exhibits transcritical, Hopf and period doubling bifurcations. The reliability is demonstrated by comparing the results to those obtained by a reduction to a Hamiltonian Kaplan-Yorke system and to those obtained by direct application of collocation methods (the latter also yield estimates for positive Lyapunov exponents in the chaotic regime. We conclude that the methodology described here works well for a class of delay equations for which currently no tailor-made tools exist (and for which it is doubtful that these will ever be constructed.

  20. Noisy zigzag transition, fluctuations, and thermal bifurcation threshold

    Science.gov (United States)

    Delfau, Jean-Baptiste; Coste, Christophe; Saint Jean, Michel

    2013-06-01

    We study the zigzag transition in a system of particles with screened electrostatic interaction, submitted to a thermal noise. At finite temperature, this configurational phase transition is an example of noisy supercritical pitchfork bifurcation. The measurements of transverse fluctuations allow a complete description of the bifurcation region, which takes place between the deterministic threshold and a thermal threshold beyond which thermal fluctuations do not allow the system to flip between the symmetric zigzag configurations. We show that a divergence of the saturation time for the transverse fluctuations allows a precise and unambiguous definition of this thermal threshold. Its evolution with the temperature is shown to be in good agreement with theoretical predictions from noisy bifurcation theory.

  1. An explicit example of Hopf bifurcation in fluid mechanics

    Science.gov (United States)

    Kloeden, P.; Wells, R.

    1983-01-01

    It is observed that a complete and explicit example of Hopf bifurcation appears not to be known in fluid mechanics. Such an example is presented for the rotating Benard problem with free boundary conditions on the upper and lower faces, and horizontally periodic solutions. Normal modes are found for the linearization, and the Veronis computation of the wave numbers is modified to take into account the imposed horizontal periodicity. An invariant subspace of the phase space is found in which the hypotheses of the Joseph-Sattinger theorem are verified, thus demonstrating the Hopf bifurcation. The criticality calculations are carried through to demonstrate rigorously, that the bifurcation is subcritical for certain cases, and to demonstrate numerically that it is subcritical for all the cases in the paper.

  2. Local bifurcation of electrohydrodynamic waves on a conducting fluid

    Science.gov (United States)

    Lin, Zhi; Zhu, Yi; Wang, Zhan

    2017-03-01

    We are concerned with progressive waves propagating on a two-dimensional conducting fluid when a uniform electric field is applied in the direction perpendicular to the undisturbed free surface. The competing effects of gravity, surface tension, and electrically induced forces are investigated using both analytical and numerical techniques for an inviscid and incompressible fluid flowing irrotationally. We simplify the full Euler equations by expanding and truncating the Dirichlet-Neumann operators in the Hamiltonian formulation of the problem. The numerical results show that when the electric parameter is in a certain range, the bifurcation structure near the minimum of the phase speed is rich with Stokes, solitary, generalized solitary, and dark solitary waves. In addition to symmetric solutions, asymmetric solitary waves featuring a multi-packet structure are found to occur along a branch of asymmetric generalized solitary waves that itself bifurcates from Stokes waves of finite amplitude. The detailed bifurcation diagrams, together with typical wave profiles, are presented.

  3. Spike-train bifurcation scaling in two coupled chaotic neurons

    Energy Technology Data Exchange (ETDEWEB)

    Huerta, R.; Rabinovich, M.I. [Institute for Nonlinear Science, University of California, San Diego, La Jolla, California 92093-0402 (United States); Abarbanel, H.D. [Department of Physics and Marine Physical Laboratory, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0402 (United States); Bazhenov, M. [Howard Hughes Medical Institute, The Salk Institute, Computational Neurobiology Laboratory, La Jolla, California 92037 (United States)

    1997-03-01

    We investigate the variation of the out-of-phase periodic rhythm produced by two chaotic neurons {bold (}Hindmarsh-Rose neurons [J. L. Hindmarsh and R. M. Rose, Proc. R. Soc. London B {bold 221}, 87 (1984)]{bold )} coupled by electrical and reciprocally synaptic connections. The exploration of a two-parametric bifurcation diagram, as a function of the strength of the electrical and inhibitory coupling, reveals that the periodic rhythms associated to the limit cycles bounded by saddle-node bifurcations, undergo a strong variation as a function of small changes of electrical coupling. We found that there is a scaling law for the bifurcations of the limit cycles as a function of the strength of both couplings. From the functional point of view of this mixed typed of coupling, the small variation of electrical coupling provides a high sensitivity for period regulation inside the regime of out-of-phase synchronization. {copyright} {ital 1997} {ital The American Physical Society}

  4. High-resolution mapping of bifurcations in nonlinear biochemical circuits

    Science.gov (United States)

    Genot, A. J.; Baccouche, A.; Sieskind, R.; Aubert-Kato, N.; Bredeche, N.; Bartolo, J. F.; Taly, V.; Fujii, T.; Rondelez, Y.

    2016-08-01

    Analog molecular circuits can exploit the nonlinear nature of biochemical reaction networks to compute low-precision outputs with fewer resources than digital circuits. This analog computation is similar to that employed by gene-regulation networks. Although digital systems have a tractable link between structure and function, the nonlinear and continuous nature of analog circuits yields an intricate functional landscape, which makes their design counter-intuitive, their characterization laborious and their analysis delicate. Here, using droplet-based microfluidics, we map with high resolution and dimensionality the bifurcation diagrams of two synthetic, out-of-equilibrium and nonlinear programs: a bistable DNA switch and a predator-prey DNA oscillator. The diagrams delineate where function is optimal, dynamics bifurcates and models fail. Inverse problem solving on these large-scale data sets indicates interference from enzymatic coupling. Additionally, data mining exposes the presence of rare, stochastically bursting oscillators near deterministic bifurcations.

  5. Dynamical systems V bifurcation theory and catastrophe theory

    CERN Document Server

    1994-01-01

    Bifurcation theory and catastrophe theory are two of the best known areas within the field of dynamical systems. Both are studies of smooth systems, focusing on properties that seem to be manifestly non-smooth. Bifurcation theory is concerned with the sudden changes that occur in a system when one or more parameters are varied. Examples of such are familiar to students of differential equations, from phase portraits. Moreover, understanding the bifurcations of the differential equations that describe real physical systems provides important information about the behavior of the systems. Catastrophe theory became quite famous during the 1970's, mostly because of the sensation caused by the usually less than rigorous applications of its principal ideas to "hot topics", such as the characterization of personalities and the difference between a "genius" and a "maniac". Catastrophe theory is accurately described as singularity theory and its (genuine) applications. The authors of this book, the first printing of w...

  6. Bifurcations in the optimal elastic foundation for a buckling column

    Energy Technology Data Exchange (ETDEWEB)

    Rayneau-Kirkhope, Daniel, E-mail: ppxdr@nottingham.ac.u [School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD (United Kingdom); Farr, Robert [Unilever R and D, Olivier van Noortlaan 120, AT3133, Vlaardingen (Netherlands); London Institute for Mathematical Sciences, 22 South Audley Street, Mayfair, London (United Kingdom); Ding, K. [Department of Physics, Fudan University, Shanghai, 200433 (China); Mao, Yong [School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD (United Kingdom)

    2010-12-01

    We investigate the buckling under compression of a slender beam with a distributed lateral elastic support, for which there is an associated cost. For a given cost, we study the optimal choice of support to protect against Euler buckling. We show that with only weak lateral support, the optimum distribution is a delta-function at the centre of the beam. When more support is allowed, we find numerically that the optimal distribution undergoes a series of bifurcations. We obtain analytical expressions for the buckling load around the first bifurcation point and corresponding expansions for the optimal position of support. Our theoretical predictions, including the critical exponent of the bifurcation, are confirmed by computer simulations.

  7. Bifurcation-free design method of pulse energy converter controllers

    Energy Technology Data Exchange (ETDEWEB)

    Kolokolov, Yury [Institute of Applied Mathematics, Informatics and Control, Yugra State University, 16 Chekhova str., Khanty-Mansiysk 628012 (Russian Federation); Ustinov, Pavel [Department of Design and Technology of Electronic and Computer Systems, Orel State Technical University, 29 Naugorskoye Shosse, Orel 302020 (Russian Federation); CReSTIC, Universite de Reims Champagne-Ardenne, Moulin de la Housse, BP 1039, Reims Cedex 2, 51687 (France)], E-mail: pavel-ustinov@yandex.ru; Essounbouli, Najib; Hamzaoui, Abdelaziz [CReSTIC, Universite de Reims Champagne-Ardenne, Moulin de la Housse, BP 1039, Reims Cedex 2, 51687 (France)

    2009-12-15

    In this paper, a design method of pulse energy converter (PEC) controllers is proposed. This method develops a classical frequency domain design, based on the small signal modeling, by means of an addition of a nonlinear dynamics analysis stage. The main idea of the proposed method consists in fact that the PEC controller, designed with an application of the small signal modeling, is tuned after with taking into the consideration an essentially nonlinear nature of the PEC that makes it possible to avoid bifurcation phenomena in the PEC dynamics at the design stage (bifurcation-free design). Also application of the proposed method allows an improvement of the designed controller performance. The application of this bifurcation-free design method is demonstrated on an example of the controller design of direct current-direct current (DC-DC) buck converter with an input electromagnetic interference filter.

  8. Dependence of morphological changes of the carotid arteries on essential hypertension and accompanying risk factors.

    Science.gov (United States)

    Zizek, B; Poredos, P

    2002-03-01

    to evaluate morphological changes (intima-media thickness, IMT) of the carotid arteries in patients being treated for essential hypertension (EH), and to discover whether this abnormality can be detected in normotensive offspring of subjects with EH (familial trait, FT); and to investigate the interrelationship between IMT and accompanying risk factors. cross-sectional study. angiology department, university teaching hospital. the study encompassed 172 subjects, of whom 46 were treated hypertonics aged 40-55 (49) years, and 44 age matched, normotensive volunteers as controls. We also investigated 41 normotensives with FT for essential hypertension aged 20-30 (25) years and 41 age- and sex-matched controls without FT. the hypertensive subjects were being treated either with long-acting calcium-channel antagonists or ACE-inhibitors. using high resolution ultrasound, IMT of the carotid bifurcation and of the common carotid artery was measured. In the hypertensives, the mean IMT was greater than that in the controls (0.92 (0.10) mm vs 0.72 (0.07) mm; p<0.00005). The IMT was independently related to accompanying risk factors: a positive family history of hypertension, age of the patient, duration of EH and the level of systolic/diastolic blood pressure (BP), body mass index and total/LDL-cholesterol. In subjects with FT, IMT was also greater compared to the control group (0.60 (0.05) mm vs 0.55 (0.04) mm; p<0.00005). IMT was not related to BP values. In treated essential patients with the EH, the IMT was increased. Individuals with FT also had greater IMT in the absence of elevated BP. The IMT in hypertensives was related to accompanying risk factors, which could be pathogenetic determinants of EH and/or its complications.

  9. Global bifurcations in a piecewise-smooth Cournot duopoly game

    Energy Technology Data Exchange (ETDEWEB)

    Tramontana, Fabio, E-mail: f.tramontana@univpm.i [Universita degli Studi di Urbino, Department of Economics and Quantitative Methods, Via Saffi 42, 61029 Urbino (Italy); Gardini, Laura, E-mail: laura.gardini@uniurb.i [Universita degli Studi di Urbino, Department of Economics and Quantitative Methods, Via Saffi 42, 61029 Urbino (Italy); Puu, Toenu [CERUM, Umea University, SE-90187 Umea (Sweden)

    2010-12-15

    The object of the work is to perform the global analysis of the Cournot duopoly model with isoelastic demand function and unit costs, presented in Puu . The bifurcation of the unique Cournot fixed point is established, which is a resonant case of the Neimark-Sacker bifurcation. New properties associated with the introduction of horizontal branches are evidenced. These properties differ significantly when the constant value is zero or positive and small. The good behavior of the case with positive constant is proved, leading always to positive trajectories. Also when the Cournot fixed point is unstable, stable cycles of any period may exist.

  10. Global Bifurcation of a Novel Computer Virus Propagation Model

    OpenAIRE

    Ren, Jianguo; Xu, Yonghong; Liu, Jiming

    2014-01-01

    In a recent paper by J. Ren et al. (2012), a novel computer virus propagation model under the effect of the antivirus ability in a real network is established. The analysis there only partially uncovers the dynamics behaviors of virus spread over the network in the case where around bifurcation is local. In the present paper, by mathematical analysis, it is further shown that, under appropriate parameter values, the model may undergo a global B-T bifurcation, and the curves of saddle-node bif...

  11. Discretizing the transcritical and pitchfork bifurcations – conjugacy results

    KAUST Repository

    Lóczi, Lajos

    2015-01-07

    © 2015 Taylor & Francis. We present two case studies in one-dimensional dynamics concerning the discretization of transcritical (TC) and pitchfork (PF) bifurcations. In the vicinity of a TC or PF bifurcation point and under some natural assumptions on the one-step discretization method of order (Formula presented.) , we show that the time- (Formula presented.) exact and the step-size- (Formula presented.) discretized dynamics are topologically equivalent by constructing a two-parameter family of conjugacies in each case. As a main result, we prove that the constructed conjugacy maps are (Formula presented.) -close to the identity and these estimates are optimal.

  12. Bifurcation in tidal streams of Sagittarius Dwarf Galaxy: Numerical Simulations

    Science.gov (United States)

    Camargo Camargo, Y.; Casas-Miranda, R.

    2018-01-01

    We performed N-body simulations between Sagittarius dwarf galaxy and the Milky Way. The Sagittarius galaxy is modeled with two components: dark matter halo and stellar disc. The Milky Way is modeled with three components: dark matter halo, stellar disc and bulge. The goal of this work is to reproduce the bifurcations in the tidal tails and the physical properties of the Sagittarius dwarf galaxy. For it, we simulated the interaction of the progenitor of this galaxy with the Milky Way. Although bifurcations could be reproduced, the position and physical properties of Sagittarius remnant could not be obtained simultaneously.

  13. An Approach to Robust Control of the Hopf Bifurcation

    Directory of Open Access Journals (Sweden)

    Giacomo Innocenti

    2011-01-01

    Full Text Available The paper illustrates a novel approach to modify the Hopf bifurcation nature via a nonlinear state feedback control, which leaves the equilibrium properties unchanged. This result is achieved by recurring to linear and nonlinear transformations, which lead the system to locally assume the ordinary differential equation representation. Third-order models are considered, since they can be seen as proper representatives of a larger class of systems. The explicit relationship between the control input and the Hopf bifurcation nature is obtained via a frequency approach, that does not need the computation of the center manifold.

  14. Carotid stenosis, x-ray of the right artery (image)

    Science.gov (United States)

    ... the right carotid artery showing a severe narrowing (stenosis) of the internal carotid artery just past the ... artery or ulceration in the area after the stenosis in this close-up film. Note the narrowed ...

  15. Normalization of catecholamine production following resection of phaeochromocytoma positively influences carotid vascular remodelling.

    Science.gov (United States)

    Bernini, Giampaolo; Galetta, Fabio; Franzoni, Ferdinando; Bardini, Michele; Taurino, Chiara; Moretti, Angelica; Bernini, Matteo; Berti, Piero; Miccoli, Paolo; Salvetti, Antonio

    2008-08-01

    To evaluate the influence of plasma catecholamines on the vascular structure in humans, the effects of catecholamine normalization on the carotid wall of patients with phaeochromocytoma (PHEO) were investigated. A prospective study in patients with PHEO before and after (first follow-up: 20.5+/-1.8 months, second follow-up: 31.5+/-2.2 months) successful surgery was conducted in the University Referral Center for Blood Pressure Diseases. Ten consecutive patients with PHEOs and ten age- and blood pressure-matched controls were investigated. Intima-media thickness (IMT) by two-dimensional conventional ultrasonography and corrected ultrasonic integrated backscatter signal (C-IBS) analysis of carotid arteries were investigated in basal conditions and after mass removal. In PHEOs, at variance with the expected reduction in metanephrines and catecholamines, no variation in body weight, blood pressure and lipid profile was observed after operation. IMT and C-IBS values in patients with PHEO were greater (at least P<0.01) than in controls. At long-term follow-up after surgery, a significant reduction in mean carotid IMT (P<0.0009) and C-IBS (P<0.009) values was observed. A significant correlation (r=0.54, P<0.03) was found between absolute reduction in C-IBS values and absolute decrement in urinary normetanephrine levels. Our study shows that normalization of catecholamine levels after the removal of PHEO improves carotid IMT and reduces carotid wall fibrosis even without influencing blood pressure and lipid profile. These findings confirm that high catecholamine tone in humans directly influences vascular remodelling of carotid arteries.

  16. Gender differences in patients with carotid stenosis.

    Science.gov (United States)

    Stoberock, Konstanze; Debus, Eike Sebastian; Atlihan, Gülsen; Daum, Günter; Larena-Avellaneda, Axel; Eifert, Sandra; Wipper, Sabine

    2016-01-01

    This overview analyses gender differences in prevalence, epidemiology, risk factors and therapy in patients with carotid stenosis in a systematic review. Ischemic stroke is a leading cause of death in Western society, where about 20% of cases are triggered by a carotid stenosis or occlusion, which occurs more frequently in men than in women. The stroke-protective effect of carotid endarterectomy is greater in men. Men have lower peri-procedural stroke and death rates. Particularly men with carotid stenosis and a life expectancy of at least 5 years benefit from surgical treatment. Also, the recurrence rate of ipsilateral stroke 5 years after initial surgery is lower in men than in women. It is not yet fully clarified whether there are significant gender differences regarding the outcome after endovascular versus surgical treatment. Gender differences in the outcome of carotid artery repair may be caused by biological, anatomical (smaller vessel diameter in women) or hormonal differences as well as a protracted development of atherosclerotic changes in women and different plaque morphology. Moreover, women are on average older at the time of surgery and their surgical treatment is often delayed. To reduce the risk of stroke and to improve treatment outcome especially for women, further research on gender differences and their causes is mandatory and promising.

  17. [Prevention of cerebral ictus, of carotid origin].

    Science.gov (United States)

    Tovar Martín, E

    2001-01-01

    The current incidence of stroke in Europe and the USA is about 200 per 100,000 population per annum. Eighty percent of strokes are ischaemic and 20% are due to hemorrhage. Approximately half the patients with ischaemic strike have carotid artery stenosis and about one third (10% all stroke victims) have had no warning symptoms such as transient ischaemi attacks. The European Carotid Surgery Trial (ECST) and North American Symptomatic Carotid Endarterectomy Trial (NASCET) have effectively shown that carotid endarterectomy (CEA) can prevent strokes in symptomatic patients. The benefit of operation is, at present, confined to those with at least 70% stenosis; for 30-69%, the trials have not yet reported a result. In asymptomatic patients the Veterans Administration Study and the Asymptomatic Carotid Atherosclerosis Study (ACAS) have yielded promising results that surgery may reduce the risk of TIA and minor stroke. There is as yet no convincing evidence in asymptomatic patients that moderate or severe stroke (or death) can be prevented by CEA. The aim of this trial is to determine whether CEA and appropriate best medical treatment (BMT) can improve stroke free survival time when compared with BMT alone.

  18. Direct Carotid Exposure for Neuroendovascular Approaches.

    Science.gov (United States)

    Shin, Dong Seong; Yilmaz, Ali; Ozkul, Ayca; Yeo, Dong Kyu; Hwang, Sun-Chul; Kim, Bum-Tae

    2016-11-01

    Objective The transfemoral approach is a common route for catheterization of the supra-aortic vessels in neuroendovascular therapy. However, in some cases, the patient's anatomy prevents transfemoral catheterization or distal access to the carotid s. In such cases, direct carotid exposure (DCE) for neuroendovascular approaches may be used to treat cerebrovascular diseases. Methods We present 11 cases in which we were unable to perform the distal approach and DCE was the preferred neuroendovascular treatment procedure. Results DCE was performed on 11 patients with cerebral aneurysm (n = 8), carotid cavernous fistula (CCF) (n = 1), malignant brain tumor (n = 1), and carotid angioplasty and stenting (n = 1). Ten patients were female; one was male. Ages ranged from 63 to 87 years (mean: 71.36 years). Coil embolization was performed on patients with cerebral aneurysm and CCF. The patient with a malignant brain tumor underwent polyvinyl alcohol particle embolization. The only complication was a carotid artery dissection that occurred in one patient during stenting. Conclusion DCE for neuroendovascular approaches can be used as an alternative for patients with tortuous vasculature access in the femoral route. In such patients, a combination of neuroendovascular treatment and surgery in a hybrid operating room with angiography is preferred. Georg Thieme Verlag KG Stuttgart · New York.

  19. Two-parameters Hopf bifurcation in the Hodgkin-Huxley model

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jiang [School of Electrical and Automation Engineering, Tianjin University, Tianjin 300072 (China)]. E-mail: jiangwang@tju.edu.cn; Geng Jianming [School of Electrical and Automation Engineering, Tianjin University, Tianjin 300072 (China); Fei Xiangyang [School of Electrical and Automation Engineering, Tianjin University, Tianjin 300072 (China)

    2005-02-01

    In this paper, the Hodgkin-Huxley model is studied with the leakage conductance and the sodium reversal potential selected as parameters for a two-parameter Hopf-bifurcation analysis. The influence of bifurcation on the HH model was also discussed and algebra criterion in high dimension equations was used to identify Hopf bifurcation. In addition, this paper also discuses the bifurcation approach to inherited disorders of ion channels in skeletal muscle excitable membranes.

  20. A Rare Diabetic Autonomic Neuropathy: Carotid Sinus Hypersensitivity

    Directory of Open Access Journals (Sweden)

    Ahmet Kaya

    2016-03-01

    Full Text Available Carotid sinus hypersensitivity is a common cause of fainting and falls in the elderly, and can be diagnosed by carotid sinus massage. We present a 67-year-old diabetic man who was admitted with hyperglycemia. During thyroid examination, clouding of consciousness occurred with unilateral palpation. Asystole was documented for 4.8 seconds and suspected for 7 seconds upon carotid sinus massage. A cardioverter defibrillator was implanted. Carotid sinus hypersensitivity should be kept in mind when examining diabetic patients.

  1. Costs of secondary prevention of stroke by carotid endarterectomy

    DEFF Research Database (Denmark)

    Hædersdal, Carsten; Sørensen, Mette; Olsen, Tom Skyhøj

    2012-01-01

    We estimated the costs to the Danish National Health Service of preventing stroke due to carotid artery stenosis by carotid endarterectomy (CEA), including costs of identifying patients, Doppler ultrasound (DUS) examination and CEA.......We estimated the costs to the Danish National Health Service of preventing stroke due to carotid artery stenosis by carotid endarterectomy (CEA), including costs of identifying patients, Doppler ultrasound (DUS) examination and CEA....

  2. Carotid plaque burden as a measure of subclinical atherosclerosis

    DEFF Research Database (Denmark)

    Sillesen, Henrik; Muntendam, Pieter; Adourian, Aram

    2012-01-01

    The purpose of this study was to compare carotid plaque burden, carotid intima-media thickness (cIMT), ankle-brachial index (ABI), and abdominal aortic diameter (AAD) to coronary artery calcium score (CACS) in people without known cardiovascular disease.......The purpose of this study was to compare carotid plaque burden, carotid intima-media thickness (cIMT), ankle-brachial index (ABI), and abdominal aortic diameter (AAD) to coronary artery calcium score (CACS) in people without known cardiovascular disease....

  3. Role of carotid duplex imaging in carotid screening programmes – an overview

    Directory of Open Access Journals (Sweden)

    Gillard Jonathan H

    2008-07-01

    Full Text Available Abstract Background Stroke is the third most common cause of death in the UK and the largest single cause of severe disability. Each year more than 110,000 people in England suffer from a stroke which costs the National Health Service (NHS over GBP2.8 billion. Thus, it is imperative that patients at risk be screened for underlying carotid artery atherosclerosis. Aim To assess the role of carotid ultrasound in different carotid screening programmes. Methods A literature overview was carried out by using PubMed search engine, to identify different carotid screening programmes that had used ultrasound scan as a screening tool. Results It appears that the carotid ultrasound is an effective method for screening carotid artery disease in community as it effectively predicts the presence of stenosis with high accuracy. There is a need for primary care to recommend high risk patients for regular screening, to reduce stroke and transient ischemic attack (TIA related morbidity and mortality. Conclusion Screening programmes using carotid ultrasonography contribute to public health awareness and promotion which in long term could potentially benefit in disease prevention and essentially promote better standards of healthcare.

  4. Diabetes Mellitus with Chronic Complications in Relation to Carotid Endarterectomy and Carotid Artery Stenting Outcomes.

    Science.gov (United States)

    Adegbala, Oluwole; Martin, Kimberly D; Otuada, David; Akinyemiju, Tomi

    2017-01-01

    Carotid endarterectomy and carotid artery stenting are effective treatment procedures for carotid artery stenosis. Although diabetes mellitus is highly prevalent among patients undergoing these revascularization procedures, few studies have examined their impact on periprocedural outcomes. The study aimed to determine whether perioperative outcomes among patients undergoing carotid artery stenting and carotid endarterectomy varied depending on the presence of diabetes with or without chronic complications. We examined adults aged 45 and above hospitalized between 2007 and 2011 in U.S. hospitals who underwent carotid artery revascularization procedures. We used data from the Healthcare Cost and Utilization Project's Nationwide Inpatient Sample and evaluated the influence of diabetes with or without chronic complications on outcomes. Among patients receiving carotid artery stenting, diabetic patients with chronic complications had significantly increased odds of acute kidney injury (odds ratio [OR]: 3.17, 95% confidence interval [CI]: 2.31-4.35) and longer hospital stay (β: 1.98, 95% CI: 1.58-2.38) compared with nondiabetic patients. Diabetic patients with chronic complications receiving carotid endarterectomy experienced increased odds of myocardial infarction (OR: 1.12, 95% CI: .90-1.40), stroke (OR: 1.29, 95% CI: .97-1.72), perioperative infection (OR: 2.45, 95% CI: 1.29-4.65), mortality (OR: 1.48, 95% CI: 1.01-2.16), and longer hospital stay (β (days): 2.05, 95% CI: 1.90-2.20) compared with nondiabetic patients. No significant increased odds of perioperative outcomes were observed among diabetic patients without chronic complications. Uncomplicated diabetes did not appear to convey a higher odds of perioperative outcomes among patients undergoing revascularization. However, the presence of diabetes with chronic complications is an important risk factor in the carotid endarterectomy category. Copyright © 2017 National Stroke Association. Published by Elsevier

  5. [Risk factors of rupture of internal carotid artery during surgical resection of carotid body tumor].

    Science.gov (United States)

    Li, Y H; Wang, J S; Yao, C; Chang, G Q; Yin, H H; Li, S Q; Lü, W M; Hu, Z J; Wang, S M

    2017-06-13

    Objective: To investigate risk factors of rupture of internal carotid artery resection during carotid body tumor resection and to summarize our treatment experience. Methods: During the period from 1991 to 2016, rupture of internal carotid artery occurred in 27 patients (28 tumors) during surgical resection of carotid body tumor in the First Affiliated Hospital of Sun Yat-sen University. Their clinical and follow-up data were retrospectively collected and analyzed. For all patients underwent surgical resection during this period, Logistic regression analysis was used to investigate the risk factors of intraoperative rupture of internal carotid artery. Results: Of these 28 tumors, there were 15 (53.6%) tumors with diameter≥5 cm and 20 (71.4%) Shamblin Ⅲ tumors. Intraoperatively, shunt was applied for 8 (28.6%) cases. Thirteen (46.4%) patients underwent ligation of external carotid artery, while 2 (7.1%) patients accepted resection of cranial nerves. Direct closure/patchplasty, autologous vessels or graft reconstruction was used in 16, 10 and 2 cases, respectively. Postoperatively, stroke occurred in 4(14.3%) cases and cranial nerve deficit in 15 (53.6%) cases. During a median length of 36 (14-125) months, cranial nerve deficit persisted in 5 cases. Follow-up radiologic examination indicated 3 (10.7%) cases of targeted vessel occlusion. However, no new-onset stroke was identified. Among all patients underwent surgical resection of carotid body tumor, female (OR=3.650, P=0.012), age≤25 years old (OR=3.710, P=0.013) and Shamblin Ⅲ tumor (OR=4.631, P=0.008) increase the risks of intraoperative carotid artery rupture. Conclusions: Shamblin Ⅲ tumor is the predictor of rupture of internal carotid artery. Intraoperative, properly increased blood pressure, intraoperative heparinization and use of shunt for those cases without well-compensated cranial collateral arteries are likely to decreasing the incidence of stroke.

  6. Risk Factors for Stroke, Myocardial Infarction, or Death Following Carotid Endarterectomy : Results from the International Carotid Stenting Study

    NARCIS (Netherlands)

    Doig, D.; Turner, E. L.; Dobson, J.; Featherstone, R. L.; De Borst, G. J.; Stansby, G.; Beard, J. D.; Engelter, S. T.; Richards, T.; Brown, M. M.

    2015-01-01

    Objectives Carotid endarterectomy (CEA) is standard treatment for symptomatic carotid artery stenosis but carries a risk of stroke, myocardial infarction (MI), or death. This study investigated risk factors for these procedural complications occurring within 30 days of endarterectomy in the

  7. Risk Factors For Stroke, Myocardial Infarction, or Death Following Carotid Endarterectomy: Results From the International Carotid Stenting Study

    NARCIS (Netherlands)

    Doig, D.; Turner, E. L.; Dobson, J.; Featherstone, R. L.; de Borst, G. J.; Stansby, G.; Beard, J. D.; Engelter, S. T.; Richards, T.; Brown, M. M.; Algra, A.; Bamford, J.; Beard, J.; Bland, M.; Bradbury, A. W.; Clifton, A.; Gaines, P.; Collins, R.; Molyneux, A.; Naylor, R.; Warlow, C.; Ferro, J. M.; Thomas, D.; Bonati, L. H.; Coward, L.; Ederle, J.; Featherstone, R. F.; Tindall, H.; McCabe, D. J.; Wallis, A.; Brooks, M.; Chambers, B.; Chan, A.; Chu, P.; Clark, D.; Dewey, H.; Donnan, G.; Fell, G.; Hoare, M.; Molan, M.; Roberts, A.; Roberts, N.; Beiles, B.; Bladin, C.; Clifford, C.; Grigg, M.; New, G.; Bell, R.; Bower, S.; Chong, W.; Holt, M.; Saunder, A.; Than, P. G.; Gett, S.; Leggett, D.; McGahan, T.; Quinn, J.; Ray, M.; Wong, A.; Woodruff, P.; Foreman, R.; Schultz, D.; Scroop, R.; Stanley, B.; Allard, B.; Atkinson, N.; Cambell, W.; Davies, S.; Field, P.; Milne, P.; Mitchell, P.; Tress, B.; Yan, B.; Beasley, A.; Dunbabin, D.; Stary, D.; Walker, S.; Cras, P.; d'Archambeau, O.; Hendriks, J. M.; van Schil, P.; St Blasius, A. Z.; Bosiers, M.; Deloose, K.; van Buggenhout, E.; de Letter, J.; Devos, V.; Ghekiere, J.; Vanhooren, G.; Astarci, P.; Hammer, F.; Lacroix, V.; Peeters, A.; Verbist, J.; Blair, J. F.; Caron, J. L.; Daneault, N.; Giroux, M. F.; Guilbert, F.; Lanthier, S.; Lebrun, L. H.; Oliva, V.; Raymond, J.; Roy, D.; Soulez, G.; Weill, A.; Hill, M.; Hu, W.; Hudion, M.; Morrish, W.; Sutherland, G.; Wong, J.; Albäck, A.; Harno, H.; Ijäs, P.; Kaste, M.; Lepäntalo, M.; Mustanoja, S.; Paananen, T.; Porras, M.; Putaala, J.; Railo, M.; Sairanen, T.; Soinne, L.; Vehmas, A.; Vikatmaa, P.; Goertler, M.; Halloul, Z.; Skalej, M.; Brennan, P.; Kelly, C.; Leahy, A.; Moroney, J.; Thornton, J.; Koelemay, M. J.; Nederkoorn, P. J.; Reekers, J. A.; Roos, Y. B.; Koudstaal, P. J.; Pattynama, P. M.; van der Lugt, A.; van Dijk, L. C.; van Sambeek, M. R.; van Urk, H.; Verhagen, H. J.; Bruijninckx, C. M.; de Bruijn, S. F.; Keunen, R.; Knippenberg, B.; Mosch, A.; Treurniet, F.; van Dijk, L.; van Overhagen, H.; Wever, J.; de Beer, F. C.; van den Berg, J. S.; van Hasselt, B. A.; Zeilstra, D. J.; Boiten, J.; van Otterloo, J. C.; de Vries, A. C.; Lycklama a Nijeholt, G. J.; van der Kallen, B. F.; Blankensteijn, J. D.; de Leeuw, F. E.; Kool, L. J.; van der Vliet, J. A.; de Kort, G. A.; Kapelle, L. J.; Lo, T. H.; Mali, W. P.; Moll, F.; van der Worp, H. B.; Verhagen, H.; Barber, P. A.; Bourchier, R.; Hill, A.; Holden, A.; Stewart, J.; Bakke, S. J.; Krohg-Sørensen, K.; Skjelland, M.; Tennøe, B.; Bialek, P.; Biejat, Z.; Czepiel, W.; Czlonkowska, A.; Dowzenko, A.; Jedrzejewska, J.; Kobayashi, A.; Lelek, M.; Polanski, J.; Kirbis, J.; Milosevic, Z.; Zvan, B.; Blasco, J.; Chamorro, A.; Macho, J.; Obach, V.; Riambau, V.; San Roman, L.; Branera, J.; Canovas, D.; Estela, J.; Gaibar, A. G.; Perendreu, J.; Björses, K.; Gottsater, A.; Ivancev, K.; Maetzsch, T.; Sonesson, B.; Berg, B.; Delle, M.; Formgren, J.; Gillgren, P.; Kall, T. B.; Konrad, P.; Nyman, N.; Takolander, R.; Andersson, T.; Malmstedt, J.; Soderman, M.; Wahlgren, C.; Wahlgren, N.; Binaghi, S.; Hirt, L.; Michel, P.; Ruchat, P.; Fluri, F.; Guerke, L.; Jacob, A. L.; Kirsch, E.; Lyrer, P. A.; Radue, E. W.; Stierli, P.; Wasner, M.; Wetzel, S.; Bonvin, C.; Kalangos, A.; Lovblad, K.; Murith, M.; Ruefenacht, D.; Sztajzel, R.; Higgins, N.; Kirkpatrick, P. J.; Martin, P.; Varty, K.; Adam, D.; Bell, J.; Crowe, P.; Gannon, M.; Henderson, M. J.; Sandler, D.; Shinton, R. A.; Scriven, J. M.; Wilmink, T.; D'Souza, S.; Egun, A.; Guta, R.; Punekar, S.; Seriki, D. M.; Thomson, G.; Brennan, J. A.; Enevoldson, T. P.; Gilling-Smith, G.; Gould, D. A.; Harris, P. L.; McWilliams, R. G.; Nahser, H. C.; White, R.; Prakash, K. G.; Serracino-Inglott, F.; Subramanian, G.; Symth, J. V.; Walker, M. G.; Clarke, M.; Davis, M.; Dixit, S. A.; Dorman, P.; Dyker, A.; Ford, G.; Golkar, A.; Jackson, R.; Jayakrishnan, V.; Lambert, D.; Lees, T.; Louw, S.; Macdonald, S.; Mendelow, A. D.; Rodgers, H.; Rose, J.; Wyatt, M.; Baker, T.; Baldwin, N.; Jones, L.; Mitchell, D.; Munro, E.; Thornton, M.; Baker, D.; Davis, N.; Hamilton, G.; McCabe, D.; Platts, A.; Tibballs, J.; Cleveland, T.; Dodd, D.; Lonsdale, R.; Nair, R.; Nassef, A.; Nawaz, S.; Venables, G.; Belli, A.; Cloud, G.; Halliday, A.; Markus, H.; McFarland, R.; Morgan, R.; Pereira, A.; Thompson, A.; Chataway, J.; Cheshire, N.; Gibbs, R.; Hammady, M.; Jenkins, M.; Malik, I.; Wolfe, J.; Adiseshiah, M.; Bishop, C.; Brew, S.; Brookes, J.; Jäger, R.; Kitchen, N.; Ashleigh, R.; Butterfield, S.; Gamble, G. E.; McCollum, C.; Nasim, A.; O'Neill, P.; Edwards, R. D.; Lees, K. R.; MacKay, A. J.; Moss, J.

    2015-01-01

    Objectives: Carotid endarterectomy (CEA) is standard treatment for symptomatic carotid artery stenosis but carries a risk of stroke, myocardial infarction (MI), or death. This study investigated risk factors for these procedural complications occurring within 30 days of endarterectomy in the

  8. Apolipoprotein E and carotid artery atherosclerosis - The Rotterdam study

    NARCIS (Netherlands)

    Slooter, AJC; Bots, ML; Havekes, LM; del Sol, AI; Cruts, M; Grobbee, DE; Hofman, A; Van Broeckhoven, C; Witteman, JCM; van Duijn, CM

    Background and Purpose-Carotid artery atherosclerosis is a strong predictor for future stroke. It is yet unclear whether the apolipoprotein E polymorphism (APOE) is related to atherosclerosis in the carotid arteries. The aim of the present study was to investigate the role of APOE in carotid artery

  9. Endarterectomy or carotid artery stenting : the quest continues part two

    NARCIS (Netherlands)

    Kolkert, Joe L.; Meerwaldt, Robbert; Geelkerken, Robert H.; Zeebregts, Clark J.

    BACKGROUND: Although randomized trials on carotid artery stenting (CAS) could not establish its equivalence to carotid endarterectomy (CEA) in patients with symptomatic carotid disease, CAS is rapidly evolving. Data on long-term outcome after CAS from randomized trials have now become available and

  10. Endarterectomy or carotid artery stenting : the quest continues

    NARCIS (Netherlands)

    van der Vaart, Michiel G.; Meerwaldt, Robbert; Reijnen, Michel M. P. J.; Tio, Rene A.; Zeebregts, Clark J.

    Background: Carotid endarterectomy (CEA) is still considered the "gold-standard" of the treatment of patients with significant carotid stenosis and has proven its value during past decades. However, endovascular techniques have recently been evolving. Carotid artery stenting (CAS) is challenging CEA

  11. Interobserver agreement for 10% categories of angiographic carotid stenosis

    NARCIS (Netherlands)

    D.W.J. Dippel (Diederik); P.J. Koudstaal (Peter Jan); F. van Kooten (Fop); S.L.M. Bakker (Stef)

    1997-01-01

    textabstractBACKGROUND AND PURPOSE: Although the reliability of the assessment of severe 70% to 99% carotid stenosis by carotid angiography has been proven excellent, this may not necessarily be the case for a more detailed classification of carotid stenoses by 10% categories. METHODS: Angiograms

  12. Bifurcation and Hybrid Control for A Simple Hopfield Neural Networks with Delays

    Directory of Open Access Journals (Sweden)

    Zisen Mao

    2013-01-01

    Full Text Available A detailed analysis on the Hopf bifurcation of a delayed Hopfield neural network is given. Moreover, a new hybrid control strategy is proposed, in which time-delayed state feedback and parameter perturbation are used to control the Hopf bifurcation of the model. Numerical simulation results confirm that the new hybrid controller using time delay is efficient in controlling Hopf bifurcation.

  13. Control of Fold Bifurcation Application on Chemostat around Critical Dilution Rate

    DEFF Research Database (Denmark)

    Pedersen, Kurt; Jørgensen, Sten Bay

    1999-01-01

    Based on a bifurcation analysis of a process it is possible to point out where there might be operational problems due to change of stability of the process. One such change is investigated, Fold bifurcations. This type of bifurcation is associated with hysteresis/multiple steady states, which co...

  14. A gravel-sand bifurcation : a simple model and the stability of the equilibrium states

    NARCIS (Netherlands)

    Schielen, Ralph M.J.; Blom, Astrid

    2017-01-01

    A river bifurcation, can be found in, for instance, a river delta, in braided or anabranching reaches, and in manmade side channels in restored river reaches. Depending on the partitioning of water and sediment over the bifurcating branches, the bifurcation develops toward (a) a stable state with

  15. General principles of carotid Doppler ultrasonography

    Directory of Open Access Journals (Sweden)

    Whal Lee

    2014-01-01

    Full Text Available

    Carotid Doppler ultrasonography is a popular tool for evaluating atherosclerosis of the carotid artery. Its two-dimensional gray scale can be used for measuring the intima-media thickness, which is very good biomarker for atherosclerosis and can aid in plaque characterization. The plaque morphology is related to the risk of stroke. The ulceration of plaque is also known as one of the strong predictors of future embolic event risk. Color Doppler ultrasonography and pulse Doppler ultrasonography have been used for detecting carotid artery stenosis. Doppler ultrasonography has unique physical properties. The operator should be familiar with the physics and other parameters of Doppler ultrasonography to perform optimal Doppler ultrasonography studies.

  16. Hyperhomocysteinemia and recurrent carotid stenosis

    Directory of Open Access Journals (Sweden)

    Liewald Florian

    2008-01-01

    Full Text Available Abstract Background Hyperhomocysteinemia has been identified as a potential risk for atherosclerotic disease in epidemiologic studies. This study investigates the impact of elevated serum homocysteine on restenosis after carotid endarterectomy (CEA. Methods In a retrospective study, we compared fasting plasma homocysteine levels of 51 patients who developed restenosis during an eight year period after CEA with 45 patients who did not develop restenosis. Restenosis was defined as at least 50% stenosis and was assessed by applying a routine duplex scan follow up investigation. Patients with restenosis were divided into a group with early restenosis (between 3 and 18 months postoperative, a total of 39 patients and late restenosis (19 and more months; a total of 12 patients. Results The groups were controlled for age, sex, and risk factors such as diabetes, nicotine abuse, weight, hypertension, and hyperlipidemia. Patients with restenosis had a significant lower mean homocysteine level (9.11 μmol/L; range: 3.23 μmol/L to 26.49 μmol/L compared to patients without restenosis (11.01 μmol/L; range: 5.09 μmol/L to 23.29 μmol/L; p = 0.03. Mean homocysteine level in patients with early restenosis was 8.88 μmol/L (range: 3.23–26.49 μmol/L and 9.86 μmol/L (range 4.44–19.06 μmol/L in late restenosis (p = 0.50. Conclusion The finding suggests that high plasma homocysteine concentrations do not play a significant role in the development of restenosis following CEA.

  17. Iterative Controller Tuning for Process with Fold Bifurcations

    DEFF Research Database (Denmark)

    Huusom, Jakob Kjøbsted; Poulsen, Niels Kjølstad; Jørgensen, Sten Bay

    2007-01-01

    Processes involving fold bifurcation are notoriously difficult to control in the vicinity of the fold where most often optimal productivity is achieved . In cases with limited process insight a model based control synthesis is not possible. This paper uses a data driven approach with an improved...

  18. Bifurcation analysis of nephron pressure and flow regulation

    DEFF Research Database (Denmark)

    Barfred, Mikael; Mosekilde, Erik; Holstein-Rathlou, N.-H.

    1996-01-01

    One- and two-dimensional continuation techniques are applied to study the bifurcation structure of a model of renal flow and pressure control. Integrating the main physiological mechanisms by which the individual nephron regulates the incoming blood flow, the model describes the interaction between...

  19. Bifurcation analysis can unify ecological and evolutionary aspects of ecosystems.

    NARCIS (Netherlands)

    Troost, T.A.; Kooi, B.W.; Kooijman, S.A.L.M.

    2007-01-01

    Bifurcation theory is commonly used to study the dynamical behaviour of ecosystems. It involves the analysis of points in the parameter space where the stability of the system changes qualitatively. Generally, such changes are related only to changes in environmental parameters, while the organism's

  20. A codimension two bifurcation in a railway bogie system

    DEFF Research Database (Denmark)

    Zhang, Tingting; True, Hans; Dai, Huanyun

    2017-01-01

    In this paper, a comprehensive analysis is presented to investigate a codimension two bifurcation that exists in a nonlinear railway bogie dynamic system combining theoretical analysis with numerical investigation. By using the running velocity V and the primary longitudinal stiffness (Formula pr...

  1. Bifurcation diagrams in relation to synchronization in chaotic systems

    Indian Academy of Sciences (India)

    We numerically study some of the three-dimensional dynamical systems which exhibit complete synchronization as well as generalized synchronization to show that these systems can be conveniently partitioned into equivalent classes facilitating the study of bifurcation diagrams within each class. We demonstrate how ...

  2. Improved homoclinic predictor for Bogdanov-Takens bifurcation

    NARCIS (Netherlands)

    Kuznetsov, Yuri; Meijer, Hil; Al Hdaibat, Bashir; Govaerts, Willy

    2014-01-01

    An improved homoclinic predictor at a generic codim 2 Bogdanov-Takens (BT) bifucation is derived. We use the classical ‘blow-up’ technique to reduce the canonical smooth normal form near a generic BT bifurcation to a perturbed Hamiltonian system. With a simple perturbation method, we derive explicit

  3. Bifurcation analysis and the travelling wave solutions of the Klein ...

    Indian Academy of Sciences (India)

    Math. Comput. 189, 271 (2007); Li et al, Appl. Math. Comput. 175, 61 (2006)). Keywords. Klein–Gordon–Zakharov equations; travelling wave solutions; bifurcation analysis. PACS Nos 05.45.Yv; 2.30.Jr; 04.20.Jb .... level h, it is shown that the exact periodic solutions evolute into solitary wave solution. In ref. [27], by using the ...

  4. Bifurcation analysis and the travelling wave solutions of the Klein ...

    Indian Academy of Sciences (India)

    In this paper, we investigate the bifurcations and dynamic behaviour of travelling wave solutions of the Klein–Gordon–Zakharov equations given in Shang et al, Comput. Math. Appl. 56, 1441 (2008). Under different parameter conditions, we obtain some exact explicit parametric representations of travelling wave solutions by ...

  5. Coronary bifurcation lesions treated with simple or complex stenting

    DEFF Research Database (Denmark)

    Behan, Miles W; Holm, Niels R; de Belder, Adam J

    2016-01-01

    AIMS: Randomized trials of coronary bifurcation stenting have shown better outcomes from a simple (provisional) strategy rather than a complex (planned two-stent) strategy in terms of short-term efficacy and safety. Here, we report the 5-year all-cause mortality based on pooled patient-level data...

  6. A simple SIS epidemic model with a backward bifurcation.

    Science.gov (United States)

    van den Driessche, P; Watmough, J

    2000-06-01

    It is shown that an SIS epidemic model with a non-constant contact rate may have multiple stable equilibria, a backward bifurcation and hysteresis. The consequences for disease control are discussed. The model is based on a Volterra integral equation and allows for a distributed infective period. The analysis includes both local and global stability of equilibria.

  7. Bifurcation Analysis and Chaos Control in a Discrete Epidemic System

    Directory of Open Access Journals (Sweden)

    Wei Tan

    2015-01-01

    Full Text Available The dynamics of discrete SI epidemic model, which has been obtained by the forward Euler scheme, is investigated in detail. By using the center manifold theorem and bifurcation theorem in the interior R+2, the specific conditions for the existence of flip bifurcation and Neimark-Sacker bifurcation have been derived. Numerical simulation not only presents our theoretical analysis but also exhibits rich and complex dynamical behavior existing in the case of the windows of period-1, period-3, period-5, period-6, period-7, period-9, period-11, period-15, period-19, period-23, period-34, period-42, and period-53 orbits. Meanwhile, there appears the cascade of period-doubling 2, 4, 8 bifurcation and chaos sets from the fixed point. These results show the discrete model has more richer dynamics compared with the continuous model. The computations of the largest Lyapunov exponents more than 0 confirm the chaotic behaviors of the system x→x+δ[rN(1-N/K-βxy/N-(μ+mx], y→y+δ[βxy/N-(μ+dy]. Specifically, the chaotic orbits at an unstable fixed point are stabilized by using the feedback control method.

  8. Experimental bifurcation analysis of an impact oscillator – Determining stability

    DEFF Research Database (Denmark)

    Bureau, Emil; Schilder, Frank; Elmegård, Michael

    2014-01-01

    We propose and investigate three different methods for assessing stability of dynamical equilibrium states during experimental bifurcation analysis, using a control-based continuation method. The idea is to modify or turn off the control at an equilibrium state and study the resulting behavior. A...

  9. Bifurcations of phase portraits of pendulum with vibrating suspension point

    Science.gov (United States)

    Neishtadt, A. I.; Sheng, K.

    2017-06-01

    We consider a simple pendulum whose suspension point undergoes fast vibrations in the plane of motion of the pendulum. The averaged over the fast vibrations system is a Hamiltonian system with one degree of freedom depending on two parameters. We give a complete description of bifurcations of phase portraits of this averaged system.

  10. AEROSOL TRANSPORT AND DEPOSITION IN SEQUENTIALLY BIFURCATING AIRWAYS

    Science.gov (United States)

    Deposition patterns and efficiencies of a dilute suspension of inhaled particles in three-dimensional double bifurcating airway models for both in-plane and 90 deg out-of-plane configurations have been numerically simulated assuming steady, laminar, constant-property air flow wit...

  11. Bifurcations of phase portraits of pendulum with vibrating suspension point

    OpenAIRE

    Neishtadt, Anatoly; Sheng, Kaicheng

    2016-01-01

    We consider a simple pendulum whose suspension point undergoes fast vibrations in the plane of motion of the pendulum. The averaged over the fast vibrations system is a Hamiltonian system with one degree of freedom depending on two parameters. We give complete description of bifurcations of phase portraits of this averaged system.

  12. Low-crosstalk bifurcation detectors for coupled flux qubits

    NARCIS (Netherlands)

    De Groot, P.C.; Van Loo, A.F.; Lisenfeld, J.; Schouten, R.N.; Lupa?cu, A.; Harmans, C.J.P.M.; Mooij, J.E.

    2010-01-01

    We present experimental results on the crosstalk between two ac-operated dispersive bifurcation detectors, implemented in a circuit for high-fidelity readout of two strongly coupled flux qubits. Both phase-dependent and phase-independent contributions to the crosstalk are analyzed. For proper tuning

  13. Numerical computation of bifurcations in large equilibrium systems in MATLAB.

    NARCIS (Netherlands)

    Bindel, David; Friedman, Mark; Govaerts, Willy; Hughes, Jeremy; Kuznetsov, Yuri

    2014-01-01

    The Continuation of Invariant Subspaces (CIS) algorithm produces a smoothly-varying basis for an invariant subspace R(s) of a parameter-dependent matrix A(s). We have incorporated the CIS algorithm into Cl_matcont, a Matlab package for the study of dynamical systems and their bifurcations. Using

  14. Perturbed period-doubling bifurcation. II. Experiments on Josephson junctions

    DEFF Research Database (Denmark)

    Eriksen, Gert Friis; Hansen, Jørn Bindslev

    1990-01-01

    We present experimental results on the effect of periodic perturbations on a driven, dynamic system that is close to a period-doubling bifurcation. In the preceding article a scaling law for the change of stability of such a system was derived for the case where the perturbation frequency ω...

  15. The history of surgical treatment for occlusive carotid artery diseases

    Directory of Open Access Journals (Sweden)

    Ding-biao ZHOU

    2014-01-01

    Full Text Available In this article, the history of surgical treatment for occlusive carotid artery diseases is briefly reviewed. It is emphasized that, after the results of large cohort, multicenter, randomized clinical trials, including North American Symptomatic Carotid Endarterectomy Trial (NASCET and European Carotid Surgery Trial (ECST, were reported in 1991, the important role of carotid endarterectomy (CEA for the surgical treatment of carotid atherosclerosis had already been confirmed. Although it has a late start in China, CEA has a bright and promising future.

  16. Unilateral Direct Carotid Cavernous Fistula Causing Bilateral Ocular Manifestation.

    Science.gov (United States)

    Demartini, Zeferino; Liebert, Fernando; Gatto, Luana Antunes Maranha; Jung, Thiago Simiano; Rocha, Carlos; Santos, Alex Marques Borges; Koppe, Gelson Luis

    2015-01-01

    Unilateral carotid cavernous fistula presents with ipsilateral ocular findings. Bilateral presentation is only seen in bilateral fistulas, usually associated with indirect (dural) carotid cavernous fistulas. Direct carotid cavernous fistulas are an abnormal communication between the internal carotid artery and the cavernous sinus. They typically begin with a traumatic disruption in the artery wall into the cavernous sinus, presenting with a classic triad of unilateral pulsatile exophthalmos, cranial bruit and episcleral venous engorgement. We report the case of a 38-year-old male with traumatic right carotid cavernous sinus fistula and bilateral ocular presentation successfully treated by interventional neuroradiology.

  17. For-Profit Hospital Status and Carotid Artery Stent Utilization in US Hospitals Performing Carotid Revascularization.

    Science.gov (United States)

    Chandler, Justin V; George, Benjamin P; Kelly, Adam G; Holloway, Robert G

    2017-11-01

    Carotid artery stenting may be an economically attractive procedure for hospitals and physicians. We sought to identify the association of hospital ownership (nonprofit versus for-profit) on carotid artery stenting (CAS) versus carotid endarterectomy utilization in US hospitals. Using the Nationwide Inpatient Sample admissions for cerebrovascular disease from 2008 to 2011, we identified all private, nonfederal US hospitals performing at least 20 carotid revascularization procedures annually, including carotid artery stenting (International Classification of Diseases-Ninth Revision 00.63) or carotid endarterectomy (International Classification of Diseases-Ninth Revision 38.12). We used a multilevel multivariable logistic regression controlling for patient demographics, comorbidities, and hospital characteristics, to assess the effect of hospital ownership on CAS use. Across 723 hospitals (600 nonprofit, 123 for-profit), 66 731 carotid revascularization admissions were identified. Approximately 1 in 5 (n=11 641; 17.4%) revascularizations received CAS. The mean CAS rate among nonprofit hospitals was 17.5 per 100 revascularizations (median, 11.5; interquartile range, 5.2-24.5), and the mean CAS rate among for-profit hospitals was 24.2 per 100 revascularizations (median, 16.0; interquartile range, 6.7-33.3; Pprofit hospital designation was associated with greater odds of CAS (adjusted odds ratio, 1.45; 95% confidence interval, 1.07-1.98). For-profit hospital ownership is associated with a higher rate of CAS compared to nonprofit hospitals in those receiving carotid revascularization. Further research is needed to understand the individual- and system-level factors driving this difference. © 2017 American Heart Association, Inc.

  18. Stenosis of calcified carotid artery detected on Panoramic Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Cho, So Yang; Oh, Won Mann; Yoon, Suk Ja; Yoon, Woong; Lee, Jae Seo; Kang, Byung Cheol [School of Dentistry, Chonnam National University, Seoul (Korea, Republic of); Palomo, Juan M. [Department of Orthodontics, School of Dental Medicine, Case Western Reserve University, Cleveland (United States)

    2009-09-15

    This study aimed to investigate the luminal stenosis of the internal carotid artery with calcification detected on panoramic radiographs. This study used fifty carotid arteries of 36 dental patients whose panoramic radiograph and computed tomography angiography (CTA) revealed the presence of carotid artery calcification. A neuroradiologist interpreted CTA to determine the degree of stenosis of the internal carotid arteries. The degree of stenosis was stratified in four stages; normal (no stenosis), mild stenosis (1-49%), moderate stenosis (50-69%) and severe stenosis (70-99%). Among the fifty carotid arteries with calcification detected on both panoramic radiography and CTA, 20 carotid arteries (40%) were normal, 29 carotid arteries (18%) had mild stenosis, 1 carotid artery (2%) had moderate stenosis, and there was none with severe stenosis. Sixty percent of the carotid arteries with calcification detected on both panoramic radiography and CTA had internal luminal stenosis, and two percent had moderate stenosis. When carotid atheroma is detected on panoramic radiograph, it is possible that the dental patient has luminal stenosis of the internal carotid artery.

  19. Stroke prevention-surgical and interventional approaches to carotid stenosis

    Directory of Open Access Journals (Sweden)

    Kumar Rajamani

    2013-01-01

    Full Text Available Extra cranial carotid artery stenosis is an important cause of stroke, which often needs treatment with carotid revascularization. To prevent stroke recurrence, carotid endarterectomy (CEA has been well-established for several decades for symptomatic high and moderate grade stenosis. Carotid stenting is a less invasive alternative to CEA and several recent trials have compared the efficacy of the 2 procedures in patients with carotid stenosis. Carotid artery stenting has emerged as a potential mode of therapy for high surgical risk patients with symptomatic high-grade stenosis. This review focuses on the current data available that will enable the clinician to decide optimal treatment strategies for patients with carotid stenosis.

  20. Enhanced Phenylephrine Contractions in Rabbit Carotid Arteries ...

    African Journals Online (AJOL)

    Carotid arteries were isolated from rabbits and cut into 2mm rings, suspended in 20ml organ baths and bubbled with 95% O2, 5% CO2 and isometric ... There were no significant differences in PE contractions following exposure to intact erythrocytes and ghosts from subjects with different Hb genotypes; however, exposure ...

  1. Haemodynamic evaluation of carotid artery disease

    DEFF Research Database (Denmark)

    Sillesen, H; Schroeder, T

    1989-01-01

    Cerebral ischaemia in the region of an internal carotid artery (ICA) stenosis may be caused by embolism or cerebral hypoperfusion. A severe ICA stenosis may be well compensated by collateral blood supply, however, in some patients the capacity of the collateral blood supply is insufficient. Studi...

  2. Hemodynamic significance of internal carotid artery disease

    DEFF Research Database (Denmark)

    Schroeder, T

    1988-01-01

    a significant improvement in baseline flow occur. Flow reserve determined by cerebral vasodilation, however, will improve in most patients with hemodynamic failure. In addition, some patients in the low-pressure group develop marked, but temporary, hyperperfusion after reconstruction of very high grade carotid...

  3. Carotid artery revascularization : Surgical and endovascular developments

    NARCIS (Netherlands)

    Borst, G.J. de

    2007-01-01

    Carotid artery revascularization. Surgical and endovascular developments. Stroke is among the most disabling chronic diseases and the third major cause of death in the Western world. In the Netherlands around 12 per 1000 inhabitants suffers a stroke, and in 2005 over 10.000 people died as a result

  4. INTERNAL CAROTID ENDARTERECTOMY UNDER LOCAL ANAESTHESIA

    Directory of Open Access Journals (Sweden)

    Andrej Šikovec

    2004-12-01

    Full Text Available Background. Endarterectomy of the internal carotid artery, supported by medicamental treatment, is the best method used to prevent stroke with symptomatic patients with an over 70-percent narrowing of the ipsilateral carotid artery. With patients who have successfully passed the operation the occurrence of the stroke is less often than with non-operated patients (1% vs. 6–10% per year. Therefore, it is important that the operation is carried out as safely as possible. Currently, the average acceptable rate of death and/ or severe stroke risk stands at between 2–4%. Greatest problems faced during carotid artery surgery are embolism of the affected artery during preparation, brain ischaemia during the blockade of the carotid artery, and embolism and intimal tearing due to injury of the internal carotid artery by the temporary internal shunt. Due to the risk of causing an embolism and intimal tearing, the use of the internal shunt can be dangerous. Therefore, selective usage of the shunt is recommended when necessary due to brain ischaemia.Methods. Under block/conduction anaesthesia (deep and superficial cervical block we have performed surgery on 23 patients (16 males, 7 females because of severe stenosis of the internal carotid artery (over 70%. A mixture of Xylocain 1% and Marcain 1.5% was used for the cervical block. Cerebral blood circulation was monitored by neurological testing of the patient awake during the procedure. During the procedure, we performed standard monitoring of the vital functions including the blood pressure. Additionally, the transcranial Doppler monitoring of the blood flow through the middle cerebral artery was used with 20 of the patients.Results. Even after placing the artery clamp and cutting off the blood flow through the internal carotid artery no neurological deficits were observed with 18 patients, neither did we use temporary internal shunt with them. Five patients suffered problems with loss of consciousness

  5. A bifurcation analysis of boiling water reactor on large domain of parametric spaces

    Science.gov (United States)

    Pandey, Vikas; Singh, Suneet

    2016-09-01

    The boiling water reactors (BWRs) are inherently nonlinear physical system, as any other physical system. The reactivity feedback, which is caused by both moderator density and temperature, allows several effects reflecting the nonlinear behavior of the system. Stability analyses of BWR is done with a simplified, reduced order model, which couples point reactor kinetics with thermal hydraulics of the reactor core. The linear stability analysis of the BWR for steady states shows that at a critical value of bifurcation parameter (i.e. feedback gain), Hopf bifurcation occurs. These stable and unstable domains of parametric spaces cannot be predicted by linear stability analysis because the stability of system does not include only stability of the steady states. The stability of other dynamics of the system such as limit cycles must be included in study of stability. The nonlinear stability analysis (i.e. bifurcation analysis) becomes an indispensable component of stability analysis in this scenario. Hopf bifurcation, which occur with one free parameter, is studied here and it formulates birth of limit cycles. The excitation of these limit cycles makes the system bistable in the case of subcritical bifurcation whereas stable limit cycles continues in an unstable region for supercritical bifurcation. The distinction between subcritical and supercritical Hopf is done by two parameter analysis (i.e. codimension-2 bifurcation). In this scenario, Generalized Hopf bifurcation (GH) takes place, which separates sub and supercritical Hopf bifurcation. The various types of bifurcation such as limit point bifurcation of limit cycle (LPC), period doubling bifurcation of limit cycles (PD) and Neimark-Sacker bifurcation of limit cycles (NS) have been identified with the Floquet multipliers. The LPC manifests itself as the region of bistability whereas chaotic region exist because of cascading of PD. This region of bistability and chaotic solutions are drawn on the various

  6. Carotid baroreflex response following 30 days exposure to simulated microgravity

    Science.gov (United States)

    Convertino, V. A.; Doerr, D. F.; Eckberg, D. L.; Fritsch, J. M.; Vernikos-Danellis, J.

    1989-01-01

    The mechanism of the carotid-baroreflex response to weightlessness was investigated in human subjects exposed to simulated microgravity (30 days of 6-day head-down bed rest followed by 5 days of recovery). Baroreceptor-cardiac reflex responses were elicited by a complex sequence of pressure changes delivered to a neck chamber device. The shape of the sigmoid baroreceptor-cardiac response curve was examined for alterations and the occurrence of resetting, as well as for a possible association of the impaired baroreflex function with hypotension during the postexposure orthostatic stress. It was found that the exposure to head-down bed rest caused a significant shift on the R-R interval axis, which paralleled reductions and elevations in baseline HR such that the baseline R-R (operational point) remained in the same position on the response curve. This shift in the location of the reflex relation indicates a significant resetting of the carotid baroreceptors, which may represent an appropriate adaptation which contributes to the maintenance of a constant resting arterial blood pressure before, during, and after bed rest, observed in these study.

  7. Carotid body (Thermoreceptors, sympathetic neural activation, and cardiometabolic disease

    Directory of Open Access Journals (Sweden)

    Rodrigo Iturriaga

    Full Text Available The carotid body (CB is the main peripheral chemoreceptor that senses the arterial PO2, PCO2 and pH. In response to hypoxemia, hypercapnia and acidosis, carotid chemosensory discharge elicits reflex respiratory, autonomic and cardiovascular adjustments. The classical construct considers the CB as the main peripheral oxygen sensor, triggering reflex physiological responses to acute hypoxemia and facilitating the ventilatory acclimation to chronic hypoxemia at high altitude. However, a growing body of experimental evidence supports the novel concept that an abnormally enhanced CB chemosensory input to the brainstem contributes to overactivation of the sympathetic nervous system, and consequent pathology. Indeed, the CB has been implicated in several diseases associated with increases in central sympathetic outflow. These include hypertension, heart failure, sleep apnea, chronic obstructive pulmonary disease and metabolic syndrome. Indeed, ablation of the CB has been proposed for the treatment of severe and resistant hypertension in humans. In this review, we will analyze and discuss new evidence supporting an important role for the CB chemoreceptor in the progression of autonomic and cardiorespiratory alterations induced by heart failure, obstructive sleep apnea, chronic obstructive pulmonary disease and metabolic syndrome.

  8. CAROTID ATHEROSCLEROTIC LESION IN YOUNG PATIENTS

    Directory of Open Access Journals (Sweden)

    N. V. Pizova

    2014-01-01

    Full Text Available Objective: to determine the incidence of atherosclerotic lesions in the carotid and vertebral arteries of young patients from Doppler ultrasound data and to compare the quantitatively assessed traditional risk factors of coronary heart disease (CHD with severe extracranial artery atherosclerotic lesion.Subjects and methods. Doppler ultrasound was carried out evaluating structural changes in the aortic arch branches in 1563 railway transport workers less than 45 years of age. A separate sample consisted of 68 young people with carotid atherosclerotic changes, in whom traditional risk factors for CHD were studied, so were in a control group of individuals without atherosclerotic changes (n = 38.Results. Among the examinees, carotid atherosclerotic lesion was detected in 112 (7.1 % cases, the increase in the rate of atherosclerotic plaques in patients aged 35–45 years being 9.08 %; that in the rate of local intima-media thickness in those aged 31–40 years being 5.1 %. Smoking (particularly that along with hypercholesterolemia and a family history of cardiovascular diseases, obesity (along with low activity, and emotional overstrain were defined as important risk factors in the young patients. Moreover, factor analysis has shown that smoking,hypertension, and early cardiovascular pathology in the next of kin makes the greatest contribution to the development of carotid atherosclerotic lesion.Conclusion. Among the patients less than 45 years of age, carotid and vertebral artery atherosclerotic changes were found in 112 (7.1 % cases, which were more pronounced in male patients. Smoking, particularly along with hypercholesterolemia and genetic predisposition to cardiovascular diseases, was a risk factor that had the highest impact on the degree of atherosclerotic lesion in the aortic arch branches of the young patients.

  9. Automated carotid artery intima layer regional segmentation

    Science.gov (United States)

    Meiburger, Kristen M.; Molinari, Filippo; Rajendra Acharya, U.; Saba, Luca; Rodrigues, Paulo; Liboni, William; Nicolaides, Andrew; Suri, Jasjit S.

    2011-07-01

    Evaluation of the carotid artery wall is essential for the assessment of a patient's cardiovascular risk or for the diagnosis of cardiovascular pathologies. This paper presents a new, completely user-independent algorithm called carotid artery intima layer regional segmentation (CAILRS, a class of AtheroEdge™ systems), which automatically segments the intima layer of the far wall of the carotid ultrasound artery based on mean shift classification applied to the far wall. Further, the system extracts the lumen-intima and media-adventitia borders in the far wall of the carotid artery. Our new system is characterized and validated by comparing CAILRS borders with the manual tracings carried out by experts. The new technique is also benchmarked with a semi-automatic technique based on a first-order absolute moment edge operator (FOAM) and compared to our previous edge-based automated methods such as CALEX (Molinari et al 2010 J. Ultrasound Med. 29 399-418, 2010 IEEE Trans. Ultrason. Ferroelectr. Freq. Control 57 1112-24), CULEX (Delsanto et al 2007 IEEE Trans. Instrum. Meas. 56 1265-74, Molinari et al 2010 IEEE Trans. Ultrason. Ferroelectr. Freq. Control 57 1112-24), CALSFOAM (Molinari et al Int. Angiol. (at press)), and CAUDLES-EF (Molinari et al J. Digit. Imaging (at press)). Our multi-institutional database consisted of 300 longitudinal B-mode carotid images. In comparison to semi-automated FOAM, CAILRS showed the IMT bias of -0.035 ± 0.186 mm while FOAM showed -0.016 ± 0.258 mm. Our IMT was slightly underestimated with respect to the ground truth IMT, but showed uniform behavior over the entire database. CAILRS outperformed all the four previous automated methods. The system's figure of merit was 95.6%, which was lower than that of the semi-automated method (98%), but higher than that of the other automated techniques.

  10. Automated carotid artery intima layer regional segmentation

    Energy Technology Data Exchange (ETDEWEB)

    Meiburger, Kristen M; Molinari, Filippo [Biolab, Department of Electronics, Politecnico di Torino, Torino (Italy); Acharya, U Rajendra [Department of ECE, Ngee Ann Polytechnic (Singapore); Saba, Luca [Department of Radiology, A.O.U. di Cagliari, Cagliari (Italy); Rodrigues, Paulo [Department of Computer Science, Centro Universitario da FEI, Sao Paulo (Brazil); Liboni, William [Neurology Division, Gradenigo Hospital, Torino (Italy); Nicolaides, Andrew [Vascular Screening and Diagnostic Centre, London (United Kingdom); Suri, Jasjit S, E-mail: filippo.molinari@polito.it [Fellow AIMBE, CTO, Global Biomedical Technologies Inc., CA (United States)

    2011-07-07

    Evaluation of the carotid artery wall is essential for the assessment of a patient's cardiovascular risk or for the diagnosis of cardiovascular pathologies. This paper presents a new, completely user-independent algorithm called carotid artery intima layer regional segmentation (CAILRS, a class of AtheroEdge(TM) systems), which automatically segments the intima layer of the far wall of the carotid ultrasound artery based on mean shift classification applied to the far wall. Further, the system extracts the lumen-intima and media-adventitia borders in the far wall of the carotid artery. Our new system is characterized and validated by comparing CAILRS borders with the manual tracings carried out by experts. The new technique is also benchmarked with a semi-automatic technique based on a first-order absolute moment edge operator (FOAM) and compared to our previous edge-based automated methods such as CALEX (Molinari et al 2010 J. Ultrasound Med. 29 399-418, 2010 IEEE Trans. Ultrason. Ferroelectr. Freq. Control 57 1112-24), CULEX (Delsanto et al 2007 IEEE Trans. Instrum. Meas. 56 1265-74, Molinari et al 2010 IEEE Trans. Ultrason. Ferroelectr. Freq. Control 57 1112-24), CALSFOAM (Molinari et al Int. Angiol. (at press)), and CAUDLES-EF (Molinari et al J. Digit. Imaging (at press)). Our multi-institutional database consisted of 300 longitudinal B-mode carotid images. In comparison to semi-automated FOAM, CAILRS showed the IMT bias of -0.035 {+-} 0.186 mm while FOAM showed -0.016 {+-} 0.258 mm. Our IMT was slightly underestimated with respect to the ground truth IMT, but showed uniform behavior over the entire database. CAILRS outperformed all the four previous automated methods. The system's figure of merit was 95.6%, which was lower than that of the semi-automated method (98%), but higher than that of the other automated techniques.

  11. Carotid Endarterectomy and Carotid Artery Stenting in the US Medicare Population, 1999-2014.

    Science.gov (United States)

    Lichtman, Judith H; Jones, Michael R; Leifheit, Erica C; Sheffet, Alice J; Howard, George; Lal, Brajesh K; Howard, Virginia J; Wang, Yun; Curtis, Jeptha; Brott, Thomas G

    2017-09-19

    Carotid endarterectomy and carotid artery stenting are the leading approaches to revascularization for carotid stenosis, yet contemporary data on trends in rates and outcomes are limited. To describe US national trends in performance and outcomes of carotid endarterectomy and stenting among Medicare beneficiaries from 1999 to 2014. Serial cross-sectional analysis of Medicare fee-for-service beneficiaries aged 65 years or older from 1999 to 2014 using the Medicare Inpatient and Denominator files. Spatial mixed models adjusted for age, sex, and race were fit to calculate county-specific risk-standardized revascularization rates. Mixed models were fit to assess trends in outcomes after adjustment for demographics, comorbidities, and symptomatic status. Carotid endarterectomy and carotid artery stenting. Revascularization rates per 100 000 beneficiary-years of fee-for-service enrollment, in-hospital mortality, 30-day stroke or death, 30-day stroke, myocardial infarction, or death, 30-day all-cause mortality, and 1-year stroke. During the study, 937 111 unique patients underwent carotid endarterectomy (mean age, 75.8 years; 43% women) and 231 077 underwent carotid artery stenting (mean age, 75.4 years; 49% women). There were 81 306 patients who underwent endarterectomy in 1999 and 36 325 in 2014; national rates per 100 000 beneficiary-years decreased from 298 in 1999-2000 to 128 in 2013-2014 (P endarterectomy and from 61% to 70% among patients who underwent stenting) and the proportion of symptomatic patients (all P endarterectomy and 1.13% (95% CI, 0.71% to 1.54%) among patients who underwent stenting; an absolute decrease from 1999 to 2014 was observed for endarterectomy (1.4%; 95% CI, 1.2% to 1.5%) but not stenting (-0.1%; 95% CI, -0.5% to 0.4%). Rates for 1-year ischemic stroke decreased after endarterectomy (absolute decrease, 3.5% [95% CI, 3.2% to 3.7%]; adjusted annual decrease, 2.17% [95% CI, 2.00% to 2.34%]) and stenting (absolute decrease, 1

  12. Morphological differences of the carotid body among C57/BL6 (B6), A/J, and CSS B6A1 mouse strains.

    Science.gov (United States)

    Chai, Sam; Gillombardo, Carl B; Donovan, Lucas; Strohl, Kingman P

    2011-08-15

    The C57/BL6 (B6) mouse strain exhibits post-hypoxic frequency decline and periodic breathing, as well as greater amount of irregular breathing during rest in comparison to the A/J and to the B6a1, a chromosomal substitution strain whereby the A/J chromosome 1 is bred onto the B6 background (Han et al., 2002; Yamauchi et al., 2008a,b). The hypothesis was that morphological differences in the carotid body would associate with such trait variations. After confirming strain differences in post-hypoxic ventilatory behavior, histological examination (n=8 in each group) using hematoxylin and eosin (H&E) staining revealed equivalent, well-defined tissue structure at the bifurcation of the carotid arteries, an active secretory parenchyma (type I cells) from the supportive stromal tissue, and clustering of type I cells in all three strains. Tyrosine hydroxylase (TH) immunohistochemical staining revealed a typical organization of type I cells and neurovascular components into glomeruli in all three strains. Image analysis from 5 μm sections from each strain generated a series of cytological metrics. The percent carotid body composition of TH+ type I cells in the A/J, B6 and B6a1 was 20±4%, 39±3%, and 44±3%, respectively (p=0.00004). However, cellular organization in terms of density and ultrastructure in the B6a1 is more similar to the B6 than to the A/J. These findings indicate that genetic mechanisms that produce strain differences in ventilatory function do not associate with carotid body structure or tyrosine hydroxylase morphology, and that A/J chromosome 1 does not contribute much to B6 carotid body morphology. Published by Elsevier B.V.

  13. Bifurcation study of blood flow control in the kidney

    Science.gov (United States)

    Ford Versypt, Ashlee N.; Makrides, Elizabeth; Arciero, Julia C.; Ellwein, Laura; Layton, Anita T.

    2016-01-01

    Renal blood flow is maintained within a narrow window by a set of intrinsic autoregulatory mechanisms. Here, a mathematical model of renal hemodynamics control in the rat kidney is used to understand the interactions between two major renal autoregulatory mechanisms: the myogenic response and tubuloglomerular feedback. A bifurcation analysis of the model equations is performed to assess the effects of the delay and sensitivity of the feedback system and the time constants governing the response of vessel diameter and smooth muscle tone. The results of the bifurcation analysis are verified using numerical simulations of the full nonlinear model. Both the analytical and numerical results predict the generation of limit cycle oscillations under certain physiologically relevant conditions, as observed in vivo. PMID:25747903

  14. Model Reduction of Nonlinear Aeroelastic Systems Experiencing Hopf Bifurcation

    KAUST Repository

    Abdelkefi, Abdessattar

    2013-06-18

    In this paper, we employ the normal form to derive a reduced - order model that reproduces nonlinear dynamical behavior of aeroelastic systems that undergo Hopf bifurcation. As an example, we consider a rigid two - dimensional airfoil that is supported by nonlinear springs in the pitch and plunge directions and subjected to nonlinear aerodynamic loads. We apply the center manifold theorem on the governing equations to derive its normal form that constitutes a simplified representation of the aeroelastic sys tem near flutter onset (manifestation of Hopf bifurcation). Then, we use the normal form to identify a self - excited oscillator governed by a time - delay ordinary differential equation that approximates the dynamical behavior while reducing the dimension of the original system. Results obtained from this oscillator show a great capability to predict properly limit cycle oscillations that take place beyond and above flutter as compared with the original aeroelastic system.

  15. Bifurcations and Crises in a Shape Memory Oscillator

    Directory of Open Access Journals (Sweden)

    Luciano G. Machado

    2004-01-01

    Full Text Available The remarkable properties of shape memory alloys have been motivating the interest in applications in different areas varying from biomedical to aerospace hardware. The dynamical response of systems composed by shape memory actuators presents nonlinear characteristics and a very rich behavior, showing periodic, quasi-periodic and chaotic responses. This contribution analyses some aspects related to bifurcation phenomenon in a shape memory oscillator where the restitution force is described by a polynomial constitutive model. The term bifurcation is used to describe qualitative changes that occur in the orbit structure of a system, as a consequence of parameter changes, being related to chaos. Numerical simulations show that the response of the shape memory oscillator presents period doubling cascades, direct and reverse, and crises.

  16. Local bifurcations in differential equations with state-dependent delay.

    Science.gov (United States)

    Sieber, Jan

    2017-11-01

    A common task when analysing dynamical systems is the determination of normal forms near local bifurcations of equilibria. As most of these normal forms have been classified and analysed, finding which particular class of normal form one encounters in a numerical bifurcation study guides follow-up computations. This paper builds on normal form algorithms for equilibria of delay differential equations with constant delay that were developed and implemented in DDE-Biftool recently. We show how one can extend these methods to delay-differential equations with state-dependent delay (sd-DDEs). Since higher degrees of regularity of local center manifolds are still open for sd-DDEs, we give an independent (still only partial) argument which phenomena from the truncated normal must persist in the full sd-DDE. In particular, we show that all invariant manifolds with a sufficient degree of normal hyperbolicity predicted by the normal form exist also in the full sd-DDE.

  17. Power-dependent internal loss in Josephson bifurcation amplifiers

    Science.gov (United States)

    Watanabe, Michio; Inomata, Kunihiro; Yamamoto, Tsuyoshi; Tsai, Jaw-Shen

    2009-11-01

    We have studied nonlinear superconducting resonators: λ/2 coplanar-waveguide (CPW) resonators with Josephson junctions (JJs) placed in the middle and λ/4 CPW resonators terminated by JJs, which can be used for the qubit readout as “bifurcation amplifiers.” The nonlinearity of the resonators arises from the Josephson junctions, and because of the nonlinearity, the resonators with appropriate parameters are expected to show a hysteretic response to the frequency sweep, or “bifurcation,” when they are driven with a sufficiently large power. We designed and fabricated resonators whose resonant frequencies were around 10 GHz. We characterized the resonators at low temperatures, Tresonators with increasing drive power in the relevant power range. As a possible origin of the power-dependent loss, the quasiparticle channel of conductance of the JJs is discussed.

  18. A bifurcation analysis for the Lugiato-Lefever equation

    Science.gov (United States)

    Godey, Cyril

    2017-05-01

    The Lugiato-Lefever equation is a cubic nonlinear Schrödinger equation, including damping, detuning and driving, which arises as a model in nonlinear optics. We study the existence of stationary waves which are found as solutions of a four-dimensional reversible dynamical system in which the evolutionary variable is the space variable. Relying upon tools from bifurcation theory and normal forms theory, we discuss the codimension 1 bifurcations. We prove the existence of various types of steady solutions, including spatially localized, periodic, or quasi-periodic solutions. Contribution to the Topical Issue: "Theory and Applications of the Lugiato-Lefever Equation", edited by Yanne K. Chembo, Damia Gomila, Mustapha Tlidi, Curtis R. Menyuk.

  19. Local bifurcations in differential equations with state-dependent delay

    Science.gov (United States)

    Sieber, Jan

    2017-11-01

    A common task when analysing dynamical systems is the determination of normal forms near local bifurcations of equilibria. As most of these normal forms have been classified and analysed, finding which particular class of normal form one encounters in a numerical bifurcation study guides follow-up computations. This paper builds on normal form algorithms for equilibria of delay differential equations with constant delay that were developed and implemented in DDE-Biftool recently. We show how one can extend these methods to delay-differential equations with state-dependent delay (sd-DDEs). Since higher degrees of regularity of local center manifolds are still open for sd-DDEs, we give an independent (still only partial) argument which phenomena from the truncated normal must persist in the full sd-DDE. In particular, we show that all invariant manifolds with a sufficient degree of normal hyperbolicity predicted by the normal form exist also in the full sd-DDE.

  20. Control by time delayed feedback near a Hopf bifurcation point

    Directory of Open Access Journals (Sweden)

    Sjoerd Verduyn Lunel

    2017-12-01

    Full Text Available In this paper we study the stabilization of rotating waves using time delayed feedback control. It is our aim to put some recent results in a broader context by discussing two different methods to determine the stability of the target periodic orbit in the controlled system: 1 by directly studying the Floquet multipliers and 2 by use of the Hopf bifurcation theorem. We also propose an extension of the Pyragas control scheme for which the controlled system becomes a functional differential equation of neutral type. Using the observation that we are able to determine the direction of bifurcation by a relatively simple calculation of the root tendency, we find stability conditions for the periodic orbit as a solution of the neutral type equation.

  1. Bifurcation analysis of the regulation of nociceptive neuronal activity

    Science.gov (United States)

    Dik, O. E.

    2017-11-01

    A model of the membrane of a nociceptive neuron from a rat dorsal ganglion has been used to address the problem of analyzing the regulation of nociceptive signals by 5-hydroxy-γ-pyrone-2-carboxylic acid, which is the active pharmaceutic ingredient of the analgesic Anoceptin. The study has applied bifurcation analysis to report the relationship between the values of model parameters and the type of problem solution before and after the parameters change in response to analgesic modulation.

  2. Application of the bifurcation method to the modified Boussinesq equation

    Directory of Open Access Journals (Sweden)

    Shaoyong Li

    2014-08-01

    Firstly, we give a property of the solutions of the equation, that is, if $1+u(x, t$ is a solution, so is $1-u(x, t$. Secondly, by using the bifurcation method of dynamical systems we obtain some explicit expressions of solutions for the equation, which include kink-shaped solutions, blow-up solutions, periodic blow-up solutions and solitary wave solutions. Some previous results are extended.

  3. Bifurcation for non linear ordinary differential equations with singular perturbation

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    Safia Acher Spitalier

    2016-10-01

    Full Text Available We study a family of singularly perturbed ODEs with one parameter and compare their solutions to the ones of the corresponding reduced equations. The interesting characteristic here is that the reduced equations have more than one solution for a given set of initial conditions. Then we consider how those solutions are organized for different values of the parameter. The bifurcation associated to this situation is studied using a minimal set of tools from non standard analysis.

  4. An alternative bifurcation analysis of the Rose-Hindmarsh model

    Energy Technology Data Exchange (ETDEWEB)

    Nikolov, Svetoslav [Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 4, 1113 Sofia (Bulgaria)]. E-mail: s.nikolov@imbm.bas.bg

    2005-03-01

    The paper presents an alternative study of the bifurcation behavior of the Rose-Hindmarsh model using Lyapunov-Andronov's theory. This is done on the basis of the obtained analytical formula expressing the first Lyapunov's value (this is not Lyapunov exponent) at the boundary of stability. From the obtained results the following new conclusions are made: Transition to chaos and the occurrence of chaotic oscillations in the Rose-Hindmarsh system take place under hard stability loss.

  5. Time-Periodic Einstein-Klein-Gordon Bifurcations of Kerr

    Science.gov (United States)

    Chodosh, Otis; Shlapentokh-Rothman, Yakov

    2017-12-01

    We construct one-parameter families of solutions to the Einstein-Klein-Gordon equations bifurcating off the Kerr solution such that the underlying family of spacetimes are each an asymptotically flat, stationary, axisymmetric, black hole spacetime, and such that the corresponding scalar fields are non-zero and time-periodic. An immediate corollary is that for these Klein-Gordon masses, the Kerr family is not asymptotically stable as a solution to the Einstein-Klein-Gordon equations.

  6. Bifurcation of solutions of nonlinear Sturm–Liouville problems

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    Gulgowski Jacek

    2001-01-01

    Full Text Available A global bifurcation theorem for the following nonlinear Sturm–Liouville problem is given Moreover we give various versions of existence theorems for boundary value problems The main idea of these proofs is studying properties of an unbounded connected subset of the set of all nontrivial solutions of the nonlinear spectral problem , associated with the boundary value problem , in such a way that .

  7. Carotid stenosis: what is the high-risk population?

    Directory of Open Access Journals (Sweden)

    Jong Hun Park

    Full Text Available OBJECTIVE: Prevention is the best treatment for cerebrovascular disease, which is why early diagnosis and the immediate treatment of carotid stenosis contribute significantly to reducing the incidence of stroke. Given its silent nature, 80% of stroke cases occur in asymptomatic individuals, emphasizing the importance of screening individuals with carotid stenosis and identifying high-risk groups for the disease. The aim of this study was to determine the prevalence and the most frequent risk factors for carotid stenosis. METHODS: A transversal study was conducted in the form of a stroke prevention campaign held on three nonconsecutive Saturdays. During the sessions, carotid stenosis diagnostic procedures were performed for 500 individuals aged 60 years or older who had systemic arterial hypertension and/or diabetes mellitus and/or coronary heart disease and/or a family history of stroke. RESULTS: The prevalence of carotid stenosis in the population studied was 7.4%, and the most frequent risk factors identified were mean age of 70 years, carotid bruit, peripheral obstructive arterial disease, coronary insufficiency and smoking. Independent predictive factors of carotid stenosis include the presence of carotid bruit or peripheral obstructive heart disease and/or coronary insufficiency. CONCLUSIONS: The population with peripheral obstructive heart disease and carotid bruit should undergo routine screening for carotid stenosis.

  8. Continuous Blood Glucose Monitoring May Detect Carotid Occlusion Intolerance during Carotid Artery Stenting.

    Science.gov (United States)

    Hiramatsu, Ryo; Furuse, Motomasa; Yagi, Ryokichi; Ohmura, Tomohisa; Ohnishi, Hiroyuki; Ikeda, Naokado; Nonoguchi, Naosuke; Kawabata, Shinji; Miyachi, Shigeru; Kuroiwa, Toshihiko

    2018-02-05

    The frequency of the occurrence of adverse events associated with carotid artery stenting (CAS) is usually low, but serious adverse events such as cerebral hyperperfusion syndrome (CHS) may occur. Real-time monitoring is ideal for the early detection of adverse events during the surgical procedure. This study aimed to evaluate continuous blood glucose (BG) monitoring for the detection of adverse events during CAS. Forty patients undergoing scheduled CAS were prospectively enrolled. An artificial pancreas was used for continuous BG monitoring (once per minute), using venous blood extracted at a rate of 2 mL/hr during CAS. The primary endpoint was a correlation between BG change and adverse events. CAS was discontinued in 1 patient, and BG was not measured in 5 patients (12.5%) because of the inability to extract blood. Among 34 evaluable patients, no patient developed CHS, but 3 patients (9%) experienced carotid occlusion intolerance. During CAS, BG was significantly higher in patients with carotid occlusion intolerance (median: 5 mg/dL) than in patients without carotid occlusion intolerance (median: 0 mg/dL) (P = 0.0221). A cutoff BG value ≥4 mg/dL during CAS showed 50% sensitivity and 100% specificity for the detection of carotid occlusion intolerance. There was no significant correlation between BG change and other adverse events. BG elevation may help detect carotid occlusion intolerance although it is still unknown whether BG monitoring can detect CHS. Further studies should validate that a cutoff BG elevation value of ≥4 mg/dL during CAS indicates carotid occlusion intolerance. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Bifurcation kinetics of drug uptake by Gram-negative bacteria.

    Science.gov (United States)

    Westfall, David A; Krishnamoorthy, Ganesh; Wolloscheck, David; Sarkar, Rupa; Zgurskaya, Helen I; Rybenkov, Valentin V

    2017-01-01

    Cell envelopes of many bacteria consist of two membranes studded with efflux transporters. Such organization protects bacteria from the environment and gives rise to multidrug resistance. We report a kinetic model that accurately describes the permeation properties of this system. The model predicts complex non-linear patterns of drug uptake complete with a bifurcation, which recapitulate the known experimental anomalies. We introduce two kinetic parameters, the efflux and barrier constants, which replace those of Michaelis and Menten for trans-envelope transport. Both compound permeation and efflux display transitions, which delineate regimes of efficient and inefficient efflux. The first transition is related to saturation of the transporter by the compound and the second one behaves as a bifurcation and involves saturation of the outer membrane barrier. The bifurcation was experimentally observed in live bacteria. We further found that active efflux of a drug can be orders of magnitude faster than its diffusion into a cell and that the efficacy of a drug depends both on its transport properties and therapeutic potency. This analysis reveals novel physical principles in the behavior of the cellular envelope, creates a framework for quantification of small molecule permeation into bacteria, and should invigorate structure-activity studies of novel antibiotics.

  10. Stability and bifurcation for Marchuk's model of an immune system

    Science.gov (United States)

    Marzuki, Ira Syazwani Mohamad; Roslan, Ummu'Atiqah Mohd

    2017-08-01

    The investigation of an immune system has long been and will continue to be one of dominant themes in both ecology and biology due to its importance. In this paper, we consider Marchuk's model of an immune system where this model is governed by a system of three differential equations with time. This model has two equilibrium states which are healthy state and chronic state. It is healthy state when the antigen reproduction is small while chronic state is when antigen reproduction rate is large. The objectives of this paper are to analyse the stability of this model, to summarize this stability using bifurcation diagram and to discuss interaction between the healthy and chronic states at stationary solution. The methods involved are stability theory and bifurcation theory. Our results show that healthy states are saddle and only one chronic state is asymptotically stable for a region of parameter considered. For the bifurcation's case, as we increase the value of a parameter in this model, the chronic state shows that there are increment in the number of antigen, plasma cell and the antibody production.

  11. Bifurcation in autonomous and nonautonomous differential equations with discontinuities

    CERN Document Server

    Akhmet, Marat

    2017-01-01

    This book is devoted to bifurcation theory for autonomous and nonautonomous differential equations with discontinuities of different types. That is, those with jumps present either in the right-hand-side or in trajectories or in the arguments of solutions of equations. The results obtained in this book can be applied to various fields such as neural networks, brain dynamics, mechanical systems, weather phenomena, population dynamics, etc. Without any doubt, bifurcation theory should be further developed to different types of differential equations. In this sense, the present book will be a leading one in this field. The reader will benefit from the recent results of the theory and will learn in the very concrete way how to apply this theory to differential equations with various types of discontinuity. Moreover, the reader will learn new ways to analyze nonautonomous bifurcation scenarios in these equations. The book will be of a big interest both for beginners and experts in the field. For the former group o...

  12. Intermittency and bifurcation in SEPICs under voltage-mode control

    Science.gov (United States)

    Liu, Fang

    2010-08-01

    A stroboscopic map for voltage-controlled single ended primary inductor converter (SEPIC) with pulse width modulation (PWM) is presented, where low-frequency oscillating phenomena such as quasi-periodic and intermittent quasi-periodic bifurcations occurring in the system are captured by numerical and experimental methods. According to bifurcation diagrams and nonlinear dynamical theory, the characteristics of the low-frequency oscillation and the mechanism for the appearance of the low-frequency oscillation are investigated. It is shown that as the controller parameter varies, the change in the conduction mode takes place from the continuous conduction mode (CCM) under the originally stable period one and high periodic orbits to the intermittent changes between CCM and discontinuous conduction mode (DCM), which may be related to the losing stability of the system and brought the system to exhibiting low-frequency oscillating behaviour in the time domain. Moreover, the occurrence of the intermittent quasi-periodic oscillation reflects that the system undergoes a Neimark-Sacker bifurcation.

  13. Reverse bifurcation and fractal of the compound logistic map

    Science.gov (United States)

    Wang, Xingyuan; Liang, Qingyong

    2008-07-01

    The nature of the fixed points of the compound logistic map is researched and the boundary equation of the first bifurcation of the map in the parameter space is given out. Using the quantitative criterion and rule of chaotic system, the paper reveal the general features of the compound logistic map transforming from regularity to chaos, the following conclusions are shown: (1) chaotic patterns of the map may emerge out of double-periodic bifurcation and (2) the chaotic crisis phenomena and the reverse bifurcation are found. At the same time, we analyze the orbit of critical point of the compound logistic map and put forward the definition of Mandelbrot-Julia set of compound logistic map. We generalize the Welstead and Cromer's periodic scanning technology and using this technology construct a series of Mandelbrot-Julia sets of compound logistic map. We investigate the symmetry of Mandelbrot-Julia set and study the topological inflexibility of distributing of period region in the Mandelbrot set, and finds that Mandelbrot set contain abundant information of structure of Julia sets by founding the whole portray of Julia sets based on Mandelbrot set qualitatively.

  14. Estimating the stochastic bifurcation structure of cellular networks.

    Directory of Open Access Journals (Sweden)

    Carl Song

    2010-03-01

    Full Text Available High throughput measurement of gene expression at single-cell resolution, combined with systematic perturbation of environmental or cellular variables, provides information that can be used to generate novel insight into the properties of gene regulatory networks by linking cellular responses to external parameters. In dynamical systems theory, this information is the subject of bifurcation analysis, which establishes how system-level behaviour changes as a function of parameter values within a given deterministic mathematical model. Since cellular networks are inherently noisy, we generalize the traditional bifurcation diagram of deterministic systems theory to stochastic dynamical systems. We demonstrate how statistical methods for density estimation, in particular, mixture density and conditional mixture density estimators, can be employed to establish empirical bifurcation diagrams describing the bistable genetic switch network controlling galactose utilization in yeast Saccharomyces cerevisiae. These approaches allow us to make novel qualitative and quantitative observations about the switching behavior of the galactose network, and provide a framework that might be useful to extract information needed for the development of quantitative network models.

  15. Hopf Bifurcation Control of Subsynchronous Resonance Utilizing UPFC

    Directory of Open Access Journals (Sweden)

    Μ. Μ. Alomari

    2017-06-01

    Full Text Available The use of a unified power flow controller (UPFC to control the bifurcations of a subsynchronous resonance (SSR in a multi-machine power system is introduced in this study. UPFC is one of the flexible AC transmission systems (FACTS where a voltage source converter (VSC is used based on gate-turn-off (GTO thyristor valve technology. Furthermore, UPFC can be used as a stabilizer by means of a power system stabilizer (PSS. The considered system is a modified version of the second system of the IEEE second benchmark model of subsynchronous resonance where the UPFC is added to its transmission line. The dynamic effects of the machine components on SSR are considered. Time domain simulations based on the complete nonlinear dynamical mathematical model are used for numerical simulations. The results in case of including UPFC are compared to the case where the transmission line is conventionally compensated (without UPFC where two Hopf bifurcations are predicted with unstable operating point at wide range of compensation levels. For UPFC systems, it is worth to mention that the operating point of the system never loses stability at all realistic compensation degrees and therefore all power system bifurcations have been eliminated.

  16. Bifurcation control for the Zakharov-Kusnetsov equation

    Energy Technology Data Exchange (ETDEWEB)

    Maccari, Attilio, E-mail: solitone@yahoo.i [Via Alfredo Casella 3, 00013 Mentana (Rome) (Italy)

    2010-05-01

    We consider the bifurcation control for the forced Zakharov-Kusnetsov (ZK) equation by means of delay feedback linear control terms. Using a perturbation method, we obtain two slow flow equations on the amplitude and phase of the response as well as external force-response and frequency-response curves for the fundamental resonance. We observe in the resonance response for the uncontrolled system a saddle-center bifurcation, jumps and hysteresis phenomena and, using energy considerations, we show the existence of closed orbits of the slow flow equations. A limit cycle corresponds to a two-period quasi-periodic modulated motion for the ZK equation and we demonstrate that, in certain cases, a second low frequency appears in addition to the forcing frequency and then stable two-period quasi-periodic motions are present with amplitudes depending on the initial conditions. The value of the low frequency depends on the amplitude of the external excitation. Subsequently, we compare the uncontrolled and controlled systems and, to reduce the amplitude peak of the fundamental resonance and to remove saddle-center bifurcations and two-period quasi-periodic motions, we find appropriate choices of the feedback gains and time delay.

  17. Bifurcation of solutions of separable parameterized equations into lines

    Directory of Open Access Journals (Sweden)

    Yun-Qiu Shen

    2010-09-01

    Full Text Available Many applications give rise to separable parameterized equations of the form $A(y, muz+b(y, mu=0$, where $y in mathbb{R}^n$, $z in mathbb{R}^N$ and the parameter $mu in mathbb{R}$; here $A(y, mu$ is an $(N+n imes N$ matrix and $b(y, mu in mathbb{R}^{N+n}$. Under the assumption that $A(y,mu$ has full rank we showed in [21] that bifurcation points can be located by solving a reduced equation of the form $f(y, mu=0$. In this paper we extend that method to the case that $A(y,mu$ has rank deficiency one at the bifurcation point. At such a point the solution curve $(y,mu,z$ branches into infinitely many additional solutions, which form a straight line. A numerical method for reducing the problem to a smaller space and locating such a bifurcation point is given. Applications to equilibrium solutions of nonlinear ordinary equations and solutions of discretized partial differential equations are provided.

  18. Attenuation Correction and Normalisation for Quantification of Contrast Enhancement in Ultrasound Images of Carotid Arteries.

    Science.gov (United States)

    Cheung, Wing Keung; Gujral, Dorothy M; Shah, Benoy N; Chahal, Navtej S; Bhattacharyya, Sanjeev; Cosgrove, David O; Eckersley, Robert J; Harrington, Kevin J; Senior, Roxy; Nutting, Christopher M; Tang, Meng-Xing

    2015-07-01

    An automated attenuation correction and normalisation algorithm was developed to improve the quantification of contrast enhancement in ultrasound images of carotid arteries. The algorithm first corrects attenuation artefact and normalises intensity within the contrast agent-filled lumen and then extends the correction and normalisation to regions beyond the lumen. The algorithm was first validated on phantoms consisting of contrast agent-filled vessels embedded in tissue-mimicking materials of known attenuation. It was subsequently applied to in vivo contrast-enhanced ultrasound (CEUS) images of human carotid arteries. Both in vitro and in vivo results indicated significant reduction in the shadowing artefact and improved homogeneity within the carotid lumens after the correction. The error in quantification of microbubble contrast enhancement caused by attenuation on phantoms was reduced from 55% to 5% on average. In conclusion, the proposed method exhibited great potential in reducing attenuation artefact and improving quantification in contrast-enhanced ultrasound of carotid arteries. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  19. Serum Osteoprotegerin Is Associated With Calcified Carotid Plaque: A Strobe-Compliant Observational Study.

    Science.gov (United States)

    Kwon, Ami; Choi, Yun-Seok; Choi, Yong-Won; Chung, Woo-Baek; Park, Chul-Soo; Chung, Wook-Sung; Lee, Man-Young; Youn, Ho-Joong

    2016-04-01

    Osteoprotegerin (OPG) is a kind of tumor necrosis factor, which is related to bone metabolism and vascular calcification. The increase of Osteoprotegerin concentration in serum is related to cardiovascular diseases in humans. The purpose of this study was to figure out the relevance between osteoprotegerin in serum and carotid calcification. Serum OPG concentrations were compared in 145 patients who underwent carotid sonography (average age: 68 ± 9 years old, male: female = 81:64). A calcified plaque (CP) (37 people [27%]), a noncalcified plaque (NCP) (54 people [37%]), and a nonplaque (NP) (54 people [37%]) were classified for this study. No significant differences among 3 groups were demonstrated in the distribution of age, diabetes, high blood pressure, and hyperlipidemia. Serum osteoprotegerin concentrations were significantly increased in CP group rather than NCP group or NP group; (median [interquartile range], 4016 [1410] vs 3210 [1802] pg/mL, P osteoprotegerin concentrations did not indicate a significant difference between NCP Group or NP Group. This study had proved that patient group accompanied with carotid calcification in carotid artery disease had an increased serum OPG concentration, so it could consider that OPG plays an important function on calcification related to arteriosclerosis.

  20. Usefulness of contrast-enhanced ultrasound for detection of carotid plaque ulceration in patients with symptomatic carotid atherosclerosis.

    Science.gov (United States)

    ten Kate, Gerrit L; van Dijk, Anouk C; van den Oord, Stijn C H; Hussain, Burhan; Verhagen, Hence J M; Sijbrands, Eric J G; van der Steen, Antonius F W; van der Lugt, Aad; Schinkel, Arend F L

    2013-07-15

    Previous data have indicated that carotid plaque ulceration is a strong predictor of cerebrovascular events. Standard ultrasound and color Doppler ultrasound (CDUS) scans have poor diagnostic accuracy for the detection of carotid plaque ulceration. The aim of the present prospective study was to assess the value of contrast-enhanced ultrasound (CEUS) scans for the detection of carotid plaque ulceration. The Institutional Ethics Committee approved the study protocol, and all patients provided informed consent. The patients had symptomatic stenosis of the internal carotid artery and underwent carotid computed tomographic angiography as part of their clinical evaluation. All patients underwent a CDUS examination in conjunction with CEUS. Carotid plaque ulceration was defined as the presence of ≥1 disruptions in the plaque-lumen border ≥1 × 1 mm. Carotid computed tomographic angiography was used as reference technique. The study population consisted of 20 patients (mean age 64 ± 9 years, 80% men), and 39 carotid arteries were included in the present analysis. Computed tomographic angiography demonstrated that the plaque surface was smooth in 15 (38%), irregular in 7 (18%) and ulcerated in 17 (44%) carotid arteries. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of CDUS for the detection of ulceration was 29%, 73%, 54%, 46%, and 57%, respectively. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of CEUS for the detection of ulceration was 88%, 59%, 72%, 63%, and 87%, respectively. CEUS had superior sensitivity and diagnostic accuracy for the assessment of carotid plaque ulceration compared with CDUS. CEUS improved the intrareader and inter-reader variability for the assessment of carotid plaque ulceration compared with CDUS. In conclusion, CEUS could be an additional method for the detection of carotid plaque ulceration. The role of CDUS for the assessment of carotid

  1. CT angiography helps to differentiate acute from chronic carotid occlusion: the ''carotid ring sign''

    Energy Technology Data Exchange (ETDEWEB)

    Michel, Patrik; Ntaios, George [Centre Hospitalier Universitaire Vaudois and University of Lausanne, Neurology Service, Lausanne (Switzerland); Delgado, Montserrat G. [Hospital Universitario Central de Asturias, Oviedo (Spain); Bezerra, Daniel C. [Johns Hopkins Bloomberg School of Public Health, Department of Epidemiology, Baltimore, MD (United States); Meuli, Reto; Binaghi, Stefano [Centre Hospitalier Universitaire Vaudois and University of Lausanne, Department of Radiology, Lausanne (Switzerland)

    2012-02-15

    Currently, there is no reliable method to differentiate acute from chronic carotid occlusion. We propose a novel CTA-based method to differentiate acute from chronic carotid occlusions that could potentially aid clinical management of patients. We examined 72 patients with 89 spontaneously occluded extracranial internal carotids with CT angiography (CTA). All occlusions were confirmed by another imaging modality and classified as acute (imaging <1 week of presumed occlusion) orchronic (imaging >4 weeks), based on circumstantial clinical and radiological evidence. A neuroradiologist and a neurologist blinded to clinical information determined the site of occlusion on axial sections of CTA. They also looked for (a) hypodensity in the carotid artery (thrombus), (b) contrast within the carotid wall (vasa vasorum), (c) the site of the occluded carotid, and (d) the ''carotid ring sign'' (defined as presence of a and/or b). Of 89 occluded carotids, 24 were excluded because of insufficient circumstantial evidence to determine timing of occlusion, 4 because of insufficient image quality, and 3 because of subacute timing of occlusion. Among the remaining 45 acute and 13 chronic occlusions, inter-rater agreement (kappa) for the site of proximal occlusion was 0.88, 0.45 for distal occlusion, 0.78 for luminal hypodensity, 0.82 for wall contrast, and 0.90 for carotid ring sign. The carotid ring sign had 88.9% sensitivity, 69.2% specificity, and 84.5% accuracy to diagnose acute occlusion. The carotid ring sign helps to differentiate acute from chronic carotid occlusion. If further confirmed, this information may be helpful in studying ischemic symptoms and selecting treatment strategies in patients with carotid occlusions. (orig.)

  2. Carotid Endarterectomy with Routine Shunt for Patients with Contralateral Carotid Occlusion.

    Science.gov (United States)

    Kong, Jie; Li, Jinyong; Ye, Zhidong; Fan, Xueqiang; Wen, Jianyan; Zhang, Jianbin; Liu, Peng

    2017-10-20

    This study aimed to report the clinical features and early and long-term outcomes of patients treated with carotid endarterectomy (CEA) combined with a routine shunt for carotid stenosis with the occlusion of the contralateral carotid artery (CCO), and to compare them with patients without contralateral occlusion (NO-CCO). A retrospective analysis included 301 patients who had carotid artery stenosis treated with CEA using a routine shunt. Of these patients, 35 patients and 266 patients were categorized into a CCO group and NO-CCO group, respectively. Demographics and short-term and long-term outcomes were documented and compared. The demographic characteristics were not significantly different between the two groups. The periprocedural mortality, stroke rate, and rate of periprocedural myocardial infarction were not significantly different between both groups. The mean follow-up period for long-term outcomes was 34.45 ± 22.99 months, and the Kaplan-Meier analysis showed no statistical difference between both groups regarding stroke, myocardial infarction, and mortality. CEA combined with the routine shunt is an effective and durable procedure for carotid artery stenosis patients with CCO.

  3. Carotid Endarterectomy to Remove Retained Solitaire Stent Retriever inside Carotid Stent after Mechanical Thrombectomy.

    Science.gov (United States)

    Cobb, Mary In-Ping Huang; Smith, Tony P; Brown, Patrick A; Gonzalez, L Fernando; Zomorodi, Ali R

    2017-05-01

    Tandem occlusions of the internal carotid artery (ICA) and middle cerebral artery (MCA) occur in up to a third of patients with acute ischemic strokes undergoing endovascular mechanical thrombectomy. Understanding open neurosurgical management of associated complications with this procedure is important. A 67-year-old man with acute onset of left hemiparesis and a tandem right ICA and MCA occlusion. He underwent carotid stent angioplasty of a stenotic ICA, followed by attempted Solitaire stent retrieval of an MCA clot. On withdrawal, the tines of the Solitaire stent lodged inside the Precise carotid stent. The patient was started on aspirin, Plavix, and heparin infusion, and underwent a carotid endarterectomy (CEA) with safe removal of the stents and primary vessel repair. This is the first case reported to date of a Solitaire stent becoming lodged inside a Precise carotid stent, salvaged by CEA with safe removal of the stents and primary vessel repair. We discuss the timing, indication, alternatives, and technical nuances of a CEA in this setting. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  4. Positron emission tomography measurement of periodontal 18F-fluorodeoxyglucose uptake is associated with histologically determined carotid plaque inflammation.

    Science.gov (United States)

    Fifer, Kenneth M; Qadir, Sadia; Subramanian, Sharath; Vijayakumar, Jayanthi; Figueroa, Amparo L; Truong, Quynh A; Hoffmann, Udo; Brady, Thomas J; Tawakol, Ahmed

    2011-02-22

    This study aimed to test the hypothesis that metabolic activity within periodontal tissue (a possible surrogate for periodontal inflammation) predicts inflammation in a remote atherosclerotic vessel, utilizing (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging. Several lines of evidence establish periodontal disease as an important risk factor for atherosclerosis. FDG-PET imaging is an established method for measuring metabolic activity in human tissues and blood vessels. One hundred twelve patients underwent FDG-PET imaging 92 ± 5 min after FDG administration (13 to 25 mCi). Periodontal FDG uptake was measured by obtaining standardized uptake values from the periodontal tissue of each patient, and the ratio of periodontal to background (blood) activity was determined (TBR). Standardized uptake value measurements were obtained in the carotid and aorta as well as in a venous structure. Localization of periodontal, carotid, and aortic activity was facilitated by PET coregistration with computed tomography or magnetic resonance imaging. A subset of 16 patients underwent carotid endarterectomy within 1 month of PET imaging, during which atherosclerotic plaques were removed and subsequently stained with anti-CD68 antibodies to quantify macrophage infiltration. Periodontal FDG uptake was compared with carotid plaque macrophage infiltration. Periodontal FDG uptake (TBR) is associated with carotid TBR (R = 0.64, p periodontal TBR and histologically assessed inflammation within excised carotid artery plaques (R = 0.81, p periodontal tissue correlate with macrophage infiltration within carotid plaques. These findings provide direct evidence for an association between periodontal disease and atherosclerotic inflammation. Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  5. Internal Carotid Artery Aneurysm Mimicking Peritonsillar Abscess

    Directory of Open Access Journals (Sweden)

    Jacek Brzost

    2015-01-01

    Full Text Available The extracranial internal carotid artery aneurysm (EICAA is an uncommon arterial lesion. Patients typically present with neurologic symptoms resulting from impaired cerebral perfusion and compression symptoms of cranial nerves. Often EICAA presents as a pulsatile neck mass, which is otherwise asymptomatic. We present a case of an 84-year-old female, who was initially referred to the Emergency Department for Otolaryngology with suspected peritonsillar abscess. The patient had a history of recent upper airway infection and cardiovascular comorbidities, including hypertension and ischaemic stroke complicated by extensive neurologic deficits. Physical examination revealed a compact, nonpulsatile mass in the lateral parapharyngeal space and local erythema of the mucosa. Duplex Doppler Ultrasonography and Computed Tomography revealed an atherosclerotic aneurysm of the right internal carotid artery, measuring 63×55×88 mm, stretching from the skull base to the angle of the mandible.

  6. Stenting of Extracranial Carotid Artery Stenosis

    Science.gov (United States)

    Koshimae, N.; Morimoto, T.; Nagata, K.

    2003-01-01

    Summary The purpose of this study is to evaluate our cases of cervical internal carotid artery stenosis for safty stenting. We investigate the preoperative internal carotid artery stenosis using by integrated backscatter (IBS) method of ultra sonography, comparing with the thirty five surgical specimens as to their nature, histological structure, thickness of fibrous cap. We choose the protection method according to plaque structure, and placed Easy-Wall stent or Smart stent after prePTA. We added post PTA according to the extent of expansion and IVUS findings. Calibrated IBS = IBS value (ROI) /intinal IBS value of ‘bleeding’, ‘lipiď, ‘thrombus’, fiber, ‘hyalinization’ were -27.5, -22.5, -15.2, -11.1, +2.1. That of the thin fibrous cap were -10.9*, that of thic fibrous cap were -2.4 (*p safty stenting. PMID:20591243

  7. Current management of asymptomatic carotid stenosis.

    Science.gov (United States)

    Castilla-Guerra, L; Fernández-Moreno, M C; Serrano-Rodríguez, L

    2015-05-01

    Asymptomatic carotid stenosis (ACS) is a common problem in daily clinical practice, and its management is still the subject of controversy. In contrast to symptomatic carotid disease, the main studies on surgical treatment of patients with ACS have shown only a modest benefit in the primary prevention of stroke. In addition, current medical treatment has drastically decreased the risk of stroke in patients with ACS. Selecting patients amenable to endovascular treatment and determining how and when to conduct the ultrasound follow-up of these patients are issues that still need resolving. This article analyzes two new studies underway that provide evidence for better management of ACS in daily clinical practice. Copyright © 2014 Elsevier España, S.L.U. y Sociedad Española de Medicina Interna (SEMI). All rights reserved.

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  16. Very Early Carotid Endarterectomy After Intravenous Thrombolysis.

    Science.gov (United States)

    Azzini, C; Gentile, M; De Vito, A; Traina, L; Sette, E; Fainardi, E; Mascoli, F; Casetta, I

    2016-04-01

    The timing of carotid endarterectomy (CEA) after thrombolysis is still a matter of debate. The aim of this study was to analyse a cohort of patients undergoing urgent endarterectomy after intravenous thrombolysis for acute ischaemic stroke. This was an observational study. Prospective databases were reviewed and matched to identify patients who underwent CEA early after intravenous thrombolysis (2009-14). The focus was carotid surgery performed within 12 hours of stroke onset in patients with a high grade (≥70%) symptomatic carotid stenosis, associated with vulnerable plaques or stroke in evolution, and evidence of a significant salvageable ischaemic penumbra on perfusion computed tomography scan. Demographic and clinical information, as well as data on relevant outcomes were extracted. Thirty four consecutive stroke patients who underwent CEA within 2 weeks of thrombolysis for acute ischaemic stroke and ipsilateral high grade carotid stenosis were identified. In 11 patients the surgical procedure was performed within 12 hours of the onset of symptoms. All patients showed a clinical improvement after combined treatment. The 3 month outcome was favourable (modified Rankin Scale ≤ 2) in 10 patients. No haemorrhagic complications were registered. There was neither peri-operative stroke nor stroke within 3 months of surgery. One patient died from acute myocardial infarction 3 days after intervention. This experience suggests that very early CEA after thrombolysis, aimed at removing the source of potential embolisation and restoring blood flow, may be safe and can lead to a favourable outcome. Copyright © 2015 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

  17. Global Hopf Bifurcation for a Predator-Prey System with Three Delays

    Science.gov (United States)

    Jiang, Zhichao; Wang, Lin

    2017-06-01

    In this paper, a delayed predator-prey model is considered. The existence and stability of the positive equilibrium are investigated by choosing the delay τ = τ1 + τ2 as a bifurcation parameter. We see that Hopf bifurcation can occur as τ crosses some critical values. The direction of the Hopf bifurcations and the stability of the bifurcation periodic solutions are also determined by using the center manifold and normal form theory. Furthermore, based on the global Hopf bifurcation theorem for general function differential equations, which was established by J. Wu using fixed point theorem and degree theory methods, the existence of global Hopf bifurcation is investigated. Finally, numerical simulations to support the analytical conclusions are carried out.

  18. Codimension-Two Bifurcation Analysis in DC Microgrids Under Droop Control

    Science.gov (United States)

    Lenz, Eduardo; Pagano, Daniel J.; Tahim, André P. N.

    This paper addresses local and global bifurcations that may appear in electrical power systems, such as DC microgrids, which recently has attracted interest from the electrical engineering society. Most sources in these networks are voltage-type and operate in parallel. In such configuration, the basic technique for stabilizing the bus voltage is the so-called droop control. The main contribution of this work is a codimension-two bifurcation analysis of a small DC microgrid considering the droop control gain and the power processed by the load as bifurcation parameters. The codimension-two bifurcation set leads to practical rules for achieving a robust droop control design. Moreover, the bifurcation analysis also offers a better understanding of the dynamics involved in the problem and how to avoid possible instabilities. Simulation results are presented in order to illustrate the bifurcation analysis.

  19. Dynamical Analysis and Big Bang Bifurcations of 1D and 2D Gompertz's Growth Functions

    Science.gov (United States)

    Rocha, J. Leonel; Taha, Abdel-Kaddous; Fournier-Prunaret, D.

    In this paper, we study the dynamics and bifurcation properties of a three-parameter family of 1D Gompertz's growth functions, which are defined by the population size functions of the Gompertz logistic growth equation. The dynamical behavior is complex leading to a diversified bifurcation structure, leading to the big bang bifurcations of the so-called “box-within-a-box” fractal type. We provide and discuss sufficient conditions for the existence of these bifurcation cascades for 1D Gompertz's growth functions. Moreover, this work concerns the description of some bifurcation properties of a Hénon's map type embedding: a “continuous” embedding of 1D Gompertz's growth functions into a 2D diffeomorphism. More particularly, properties that characterize the big bang bifurcations are considered in relation with this coupling of two population size functions, varying the embedding parameter. The existence of communication areas of crossroad area type or swallowtails are identified for this 2D diffeomorphism.

  20. Cerebral Ischemia Due to Traumatic Carotid Artery Dissection: Case Report

    Directory of Open Access Journals (Sweden)

    Deniz Kamacı Şener

    2012-12-01

    Full Text Available Blunt injury to the neck region may lead to carotid artery dissection and cerebral ischemia. Blunt injury to carotid artery is not frequent but determination of the presence of trauma in the history of stroke patients will provide early diagnosis and treatment of them. In this article, a case with cerebral ischemia resulting from traumatic carotid artery dissection is presented and clinical findings, diagnostic procedures and choice of treatment are discussed in the light of the literature.

  1. The haemodynamic effect of carotid endarterectomy.

    Science.gov (United States)

    Nielsen, M-Y; Sillesen, H H; Jørgensen, L G; Schroeder, T V

    2002-07-01

    to assess the haemodynamic effect of carotid artery surgery, and to relate postoperative changes to the state of cerebral circulation before revascularisation. using transcranial Doppler we studied bilateral middle cerebral artery (MCA) flow velocities before and on 1st day, 2nd or 3rd day and 4th or 5th day and 3 months after carotid surgery in 61 patients. In addition, ipsilateral MCA flow velocity was monitored continuously during surgery. Data were related to the internal carotid artery (ICA) perfusion pressure (cerebral perfusion pressure index, CPPI), measured directly before ICA clamping. postoperatively, MCA flow velocities increased significantly overall (pCPPICPPI, whereas MCA flow velocities remained increased in the group of patients with low CPPI. At 3 months flow velocities in both groups were normalised. New neurological symptoms occurred in four patients, who all had low CPPI preoperatively (22% (4/18) vs 0%; Fisher's exact test: p=0.006). some degree of hyperperfusion was seen in most patients, but the changes were significantly more pronounced in patients with preoperative hypoperfusion, who also suffered significantly more neurological complications.

  2. [Morbidity and mortality of carotid endarterectomy].

    Science.gov (United States)

    Rodríguez Pérez, A; Cabrera Morán, V; Abad Vázquez, C; Muñoz Falcón, L; Hernández Ruiz, A; Hermida Anllo, M; Cárdenes Romero, I

    1993-01-01

    In order to investigate the peroperative complications in carotid surgery, a cohort of 64 patients operated of carotid endarterectomy (EC) were evaluated. A total 78 EC were performed, 56 unilateral (EC-U) and 11 bilateral (EC-B). All the cases were managed in a similar manner regarding surgical technique, monitoring, anesthetic management and pre and postoperative care. A temporary shunt was inserted in 6 cases. The hospital mortality has been 0. We registered the following postoperative complications: arterial hypertension in 23.1 of EC-U and 18.2% of EC-B, cervical hematoma in 5.3% (EC-U) and 13.6% (EC-B), TIA in 5.3% (EC-U) and 4.5% (EC-B), stroke 1.7% (EC-U) and 4.5% (EC-B), vocal cord injury in 3.5% of EC-U and chest pain with angina in 1.7% of EC-U. A review of the mortality and morbidity in carotid surgery is done.

  3. Hyperperfusion syndrome after carotid stent angioplasty

    Energy Technology Data Exchange (ETDEWEB)

    Grunwald, I.Q.; Politi, M.; Reith, W.; Krick, C.; Karp, K.; Zimmer, A.; Struffert, T.; Kuehn, A.L.; Papanagiotou, P. [University of the Saarland, Department for Interventional and Diagnostic Neuroradiology, Homburg (Germany); Roth, C.; Haass, A. [University of the Saarland, Clinic for Neurology, Homburg (Germany)

    2009-03-15

    This study assesses the incidence and causes of hyperperfusion syndrome occurring after carotid artery stenting (CAS). We retrospectively reviewed the clinical database of 417 consecutive patients who were treated with CAS in our department to identify patients who developed hyperperfusion syndrome and/or intracranial hemorrhage. Magnetic resonance imaging (MRI) including fluid-attenuated inversion recovery and diffusion-weighted imaging was performed before and after CAS in 269 cases. A Spearman's rho nonparametric correlation was performed to determine whether there was a correlation between the occurrence/development of hyperperfusion syndrome and the patient's age, degree of stenosis on the stented and contralateral side, risk factors such as diabetes, smoking, hypertension, adiposity, gender and fluoroscopy time, and mean area of postprocedural lesions as well as preexisting lesions. Significance was established at p < 0.05. Of the 417 carotid arteries stented and where MRI was also completed, we found hyperperfusion syndrome in 2.4% (ten cases). Patients who had preexisting brain lesions (previous or acute stroke) were at a higher risk of developing hyperperfusion syndrome (p = 0.022; Spearman's rho test). We could not validate any correlation with the other patient characteristics. Extensive microvascular disease may be a predictor of hyperperfusion syndrome after carotid stent placement. We believe that further studies are warranted to predict more accurately which patients are at greater risk of developing this often fatal complication. (orig.)

  4. Approach To Unstable Plaque In Carotid Disease

    Directory of Open Access Journals (Sweden)

    Mojdeh Ghabaee

    2017-02-01

    Full Text Available Risk of cerebral infarction due to thrombo emboli originating  from carotid artery disease estimated to be near 15%, and this risk  is closely associated with the severity of luminal stenosis. But at the same time characteristics  of the plaque should be taken into account for therapeutic planning when the patient is asymptomatic and the diameter of the stenosis does not reach the threshold of 70%. Search for markers of plaque vulnerability, instability, or thromboembolic potential as complementary to the degree of the luminal stenosis in stroke risk prediction should be considered .These morphologic features of carotid plaques are increasingly believed to be one of those markers that could carry further prognostic information, and early recognition of these plaques features may identify a high-risk subgroup of patients who might particularly benefit from aggressive interventions with aggressive medical treatment. Color and duplex Doppler sonography  evaluates both  morphologic and hemodynamic   abnormalitie of carotid. Echogensity, degree of stenosis and plaque surface features are essential parameters of morphological abnormality.

  5. Extracellular matrix proteomics identifies molecular signature of symptomatic carotid plaques.

    Science.gov (United States)

    Langley, Sarah R; Willeit, Karin; Didangelos, Athanasios; Matic, Ljubica Perisic; Skroblin, Philipp; Barallobre-Barreiro, Javier; Lengquist, Mariette; Rungger, Gregor; Kapustin, Alexander; Kedenko, Ludmilla; Molenaar, Chris; Lu, Ruifang; Barwari, Temo; Suna, Gonca; Yin, Xiaoke; Iglseder, Bernhard; Paulweber, Bernhard; Willeit, Peter; Shalhoub, Joseph; Pasterkamp, Gerard; Davies, Alun H; Monaco, Claudia; Hedin, Ulf; Shanahan, Catherine M; Willeit, Johann; Kiechl, Stefan; Mayr, Manuel

    2017-04-03

    The identification of patients with high-risk atherosclerotic plaques prior to the manifestation of clinical events remains challenging. Recent findings question histology- and imaging-based definitions of the "vulnerable plaque," necessitating an improved approach for predicting onset of symptoms. We performed a proteomics comparison of the vascular extracellular matrix and associated molecules in human carotid endarterectomy specimens from 6 symptomatic versus 6 asymptomatic patients to identify a protein signature for high-risk atherosclerotic plaques. Proteomics data were integrated with gene expression profiling of 121 carotid endarterectomies and an analysis of protein secretion by lipid-loaded human vascular smooth muscle cells. Finally, epidemiological validation of candidate biomarkers was performed in two community-based studies. Proteomics and at least one of the other two approaches identified a molecular signature of plaques from symptomatic patients that comprised matrix metalloproteinase 9, chitinase 3-like-1, S100 calcium binding protein A8 (S100A8), S100A9, cathepsin B, fibronectin, and galectin-3-binding protein. Biomarker candidates measured in 685 subjects in the Bruneck study were associated with progression to advanced atherosclerosis and incidence of cardiovascular disease over a 10-year follow-up period. A 4-biomarker signature (matrix metalloproteinase 9, S100A8/S100A9, cathepsin D, and galectin-3-binding protein) improved risk prediction and was successfully replicated in an independent cohort, the SAPHIR study. The identified 4-biomarker signature may improve risk prediction and diagnostics for the management of cardiovascular disease. Further, our study highlights the strength of tissue-based proteomics for biomarker discovery. UK: British Heart Foundation (BHF); King's BHF Center; and the National Institute for Health Research Biomedical Research Center based at Guy's and St Thomas' NHS Foundation Trust and King's College London in

  6. Carotid Stump Syndrome: Case Report and Endovascular Treatment.

    Science.gov (United States)

    Dakhoul, Lara Toufic; Tawk, Rabih

    2014-01-01

    Objectives. To highlight the case of a patient with multiple transient ischemic attacks and visual disturbances diagnosed with carotid stump syndrome and managed with endovascular approach. Case Presentation. We present the case of a carotid stump syndrome in an elderly patient found to have moderate left internal carotid artery stenosis in response to an advertisement for carotid screening. After a medical therapeutic approach and a close follow-up, transient ischemic attacks recurred. Computed tomographic angiography showed an occlusion of the left internal carotid artery and the presence of moderate stenosis in the right internal carotid artery, which was treated by endovascular stenting and balloon insertion. One month later, the patient presented with visual disturbances due to the left carotid stump and severe stenosis of the left external carotid artery that was reapproached by endovascular stenting. Conclusion. Considerations should be given to the carotid stump syndrome as a source of emboli for ischemic strokes, and vascular assessment could be used to detect and treat this syndrome.

  7. Chronic Interactions Between Carotid Baroreceptors and Chemoreceptors in Obesity Hypertension

    National Research Council Canada - National Science Library

    Lohmeier, Thomas E; Iliescu, Radu; Tudorancea, Ionut; Cazan, Radu; Cates, Adam W; Georgakopoulos, Dimitrios; Irwin, Eric D

    2016-01-01

    .... We investigated the chronic interactions of these reflexes in dogs with sympathetically mediated, obesity-induced hypertension based on the hypothesis that hypoxemia and tonic activation of carotid...

  8. Deglutition syncope: a manifestation of vagal hyperactivity following carotid endarterectomy.

    Science.gov (United States)

    Endean, Eric D; Cavatassi, William; Hansler, Joseph; Sorial, Ehab

    2010-09-01

    A 61-year-old man with left amaurosis fugax and bilateral >80% internal carotid artery stenoses underwent a left carotid endarterectomy. On the first postoperative day, he developed hypotension, bradycardia, and chest pain with food ingestion. He was diagnosed as having deglutition syncope and was treated with oral anticholinergics. Similar symptoms occurred when he underwent a right carotid endarterectomy. Deglutition syncope is a neurally mediated situational syncope resulting from vagus nerve over-activity. This is the first report of deglutition syncope associated with carotid endarterectomy. It is important to recognize and differentiate these symptoms from other causes of postendarterectomy hemodynamic instability.

  9. Anaesthesia for carotid endarterectomy - general or loco-regional?

    Science.gov (United States)

    Zdrehuş, Claudiu

    2015-04-01

    Carotid endarterectomy has been widely used for the surgical treatment of carotid stenosis, and may be performed under either general or loco-regional anaesthesia. The greatest risks of carotid endarterectomy are the neurologic complications and the myocardial infarction. Anaesthetic and surgical techniques are constantly under scrutiny to try to reduce the relatively high incidence of morbidity and mortality of an operation which in itself is only preventative. Loco-regional anaesthesia is an alternative to general anaesthesia which has attracted considerable attention amid claims of a reduction in operative morbidity and mortality. This review describes the problems and some solutions for providing loco-regional or general anaesthesia for carotid endarterectomy.

  10. Bilateral hypoplasia of the internal carotid arteries with basilar aneurysm

    Energy Technology Data Exchange (ETDEWEB)

    Briganti, F.; Tortora, F.; Elefante, A. [Universita di Napoli Federico II, Dipartimento di Scienze Neurologiche, Cattedra di Neuroradiologia, 80131, Napoli (Italy); Maiuri, F. [Universita di Napoli Federico II, Department of Neurological Sciences, Neurosurgery Service, Napoli (Italy)

    2004-10-01

    We report a rare case of bilateral hypoplasia of the internal carotid arteries with an associated aneurysm of the basilar tip, studied by CT angiography, MR angiography and digital angiography. The patient became symptomatic with an episode of loss of consciousness, likely due to reduced blood perfusion. The other 20 reported cases of bilateral carotid hypoplasia (only four of which with an associated aneurysm) are reviewed. The findings of noninvasive procedures (including narrowing of the carotid canals on CT) may lead to a correct diagnosis before angiography is performed; they may also help to differentiate angiographic narrowing of the hypoplastic internal carotids from the string sign often observed in some acquired conditions. (orig.)

  11. The first derivative of the carotid displacement pulse.

    Science.gov (United States)

    Khan, A. H.; Spodick, D. H.

    1972-01-01

    The amplitude and time relationships of the carotid derivative in normal individuals and unselected cardiac patients is investigated together with the effects of different contraction strengths in patients with pulsus alternans and subjects challenged with isoproterenol and propranolol. Data regarding the relationship between the preejection period (PEP) and the ratio of peak to total amplitude of the carotid displacement pulse derivative are presented. It is found that cardiac abnormality tends to reduce the rate of rise of the carotid displacement pulse. The results obtained show that the PEP is a somewhat more sensitive index of the changes studied than the carotid displacement derivative.

  12. Markerless attenuation correction for carotid MRI surface receiver coils in combined PET/MR imaging

    Science.gov (United States)

    Eldib, Mootaz; Bini, Jason; Robson, Philip M.; Calcagno, Claudia; Faul, David D.; Tsoumpas, Charalampos; Fayad, Zahi A.

    2015-06-01

    The purpose of the study was to evaluate the effect of attenuation of MR coils on quantitative carotid PET/MR exams. Additionally, an automated attenuation correction method for flexible carotid MR coils was developed and evaluated. The attenuation of the carotid coil was measured by imaging a uniform water phantom injected with 37 MBq of 18F-FDG in a combined PET/MR scanner for 24 min with and without the coil. In the same session, an ultra-short echo time (UTE) image of the coil on top of the phantom was acquired. Using a combination of rigid and non-rigid registration, a CT-based attenuation map was registered to the UTE image of the coil for attenuation and scatter correction. After phantom validation, the effect of the carotid coil attenuation and the attenuation correction method were evaluated in five subjects. Phantom studies indicated that the overall loss of PET counts due to the coil was 6.3% with local region-of-interest (ROI) errors reaching up to 18.8%. Our registration method to correct for attenuation from the coil decreased the global error and local error (ROI) to 0.8% and 3.8%, respectively. The proposed registration method accurately captured the location and shape of the coil with a maximum spatial error of 2.6 mm. Quantitative analysis in human studies correlated with the phantom findings, but was dependent on the size of the ROI used in the analysis. MR coils result in significant error in PET quantification and thus attenuation correction is needed. The proposed strategy provides an operator-free method for attenuation and scatter correction for a flexible MRI carotid surface coil for routine clinical use.

  13. Markless Attenuation Correction for Carotid MRI Surface Receiver Coils in Combined PET/MR Imaging

    Science.gov (United States)

    Eldib, Mootaz; Bini, Jason; Robson, Philip M.; Calcagno, Claudia; Faul, David D.; Tsoumpas, Charalampos; Fayad, Zahi A.

    2015-01-01

    Purpose To evaluate the effect of attenuation of MR coils on quantitative carotid PET/MR exams. Additionally, to develop and evaluate automated attenuation correction method for flexible carotid MR coils was developed and evaluated. Methods The attenuation of the carotid coil was measured by imaging a uniform water phantom injected with 37 MBq of 18F-FDG in a combined PET/MR scanner for 24 minutes with and without the coil. In the same session, an ultra-short echo time (UTE) image of the coil on top of the phantom was acquired. Using a combination of rigid and non-rigid registration, a CT-based attenuation map was registered to the UTE image of the coil for attenuation and scatter correction. After phantom validation, the effect of the carotid coil attenuation and the attenuation correction method were evaluated in five subjects. Results Phantom studies indicated that the overall loss of PET counts due to the coil was 6.3% with local region-of-interest (ROI) errors reaching up to 18.8%. Our registration method to correct for attenuation from the coil decreased the global error and local error (ROI) to 0.8% and 3.8%, respectively. The proposed registration method accurately captured the location and shape of the coil with a maximum spatial error of 2.6 mm. Quantitative analysis in human studies correlated with the phantom findings, but was dependent on the size of the ROI used in the analysis. Conclusions MR coils result in significant error in PET quantification and thus attenuation correction is needed. The proposed strategy provides an operator-free method for attenuation and scatter correction for a flexible MRI carotid surface coil for routine clinical use. PMID:26020273

  14. Periodic orbits near bifurcations of codimension two Classical mechanics, semiclassics, and Stokes transitions

    CERN Document Server

    Schomerus, H

    1997-01-01

    We investigate classical and semiclassical aspects of codimension--two bifurcations of periodic orbits in Hamiltonian systems. A classification of these bifurcations in autonomous systems with two degrees of freedom or time-periodic systems with one degree of freedom is presented. We derive uniform approximations to be used in semiclassical trace formulas and determine also certain global bifurcations in conjunction with Stokes transitions that become important in the ensuing diffraction catastrophe integrals.

  15. Stability and Hopf Bifurcation in a Delayed SEIRS Worm Model in Computer Network

    Directory of Open Access Journals (Sweden)

    Zizhen Zhang

    2013-01-01

    Full Text Available A delayed SEIRS epidemic model with vertical transmission in computer network is considered. Sufficient conditions for local stability of the positive equilibrium and existence of local Hopf bifurcation are obtained by analyzing distribution of the roots of the associated characteristic equation. Furthermore, the direction of the local Hopf bifurcation and the stability of the bifurcating periodic solutions are determined by using the normal form theory and center manifold theorem. Finally, a numerical example is presented to verify the theoretical analysis.

  16. Critical Points and Bifurcations of the Three-Dimensional Onsager Model for Liquid Crystals

    Science.gov (United States)

    Vollmer, Michaela A. C.

    2017-11-01

    We study the bifurcation diagram of the Onsager free-energy functional for liquid crystals with orientation parameter on the sphere. In particular, we concentrate on the bifurcations from the isotropic solution for a general class of two-body interaction potentials including the Onsager kernel. Reformulating the problem as a non-linear eigenvalue problem for the kernel operator, we prove that spherical harmonics are the corresponding eigenfunctions and we present a direct relationship between the coefficients of the Taylor expansion of this class of interaction potentials and their eigenvalues. We find explicit expressions for all bifurcation points corresponding to bifurcations from the isotropic state of the Onsager free-energy functional equipped with the Onsager interaction potential. A substantial amount of our analysis is based on the use of spherical harmonics and a special algorithm for computing expansions of products of spherical harmonics in terms of spherical harmonics is presented. Using a Lyapunov-Schmidt reduction, we derive a bifurcation equation depending on five state variables. The dimension of this state space is further reduced to two dimensions by using the rotational symmetry of the problem and the invariant theory of groups. On the basis of these results, we show that the first bifurcation from the isotropic state of the Onsager interaction potential is a transcritical bifurcation and that the corresponding solution is uniaxial. In addition, we prove some global properties of the bifurcation diagram such as the fact that the trivial solution is the unique local minimiser if the bifurcation parameter is high, that it is not a local minimiser if the bifurcation parameter is small, the boundedness of all equilibria of the functional and that the bifurcation branches are either unbounded or that they meet another bifurcation branch.

  17. Stability and Hopf Bifurcation for a Delayed Computer Virus Model with Antidote in Vulnerable System

    Directory of Open Access Journals (Sweden)

    Zizhen Zhang

    2017-01-01

    Full Text Available A delayed computer virus model with antidote in vulnerable system is investigated. Local stability of the endemic equilibrium and existence of Hopf bifurcation are discussed by analyzing the associated characteristic equation. Further, direction of the Hopf bifurcation and stability of the bifurcating periodic solutions are investigated by using the normal form theory and the center manifold theorem. Finally, numerical simulations are presented to show consistency with the obtained results.

  18. Paraganglioma de cuerpo carotídeo: reporte de un caso clínico con correlación familiar Carotid body paraganglioma: clinical case report with family correlation

    Directory of Open Access Journals (Sweden)

    José Martín Toranzo Fernández

    2011-06-01

    Full Text Available Los paragangliomas de cabeza y cuello son neoplasias infrecuentes que se originan de un tejido paraganglionar del grupo braquiomérco que está ligado al desarrollo de los arcos branquiales. No son cromafines, ya que no secretan catecolaminas¹. De estos paragangliomas, el que se presenta con más frecuencia es el del cuerpo carotídeo, que se origina a partir de los paraganglios localizados en la adventicia de la bifurcación del cuerpo carotídeo².The head and neck paragangliomas are infrequent neoplases that originate from a paraganglionar tissue of the brachiomeric group that are linked to the development of the branchial arches; they are not cromafins since they do not secrete catecholamines¹. The most frequent one appears in the carotid body that originates from the paraganglions located in the adventitia of the carotid body's bifurcation².

  19. Comparative Effectiveness of Carotid Artery Stenting Versus Carotid Endarterectomy Among Medicare Beneficiaries.

    Science.gov (United States)

    Jalbert, Jessica J; Nguyen, Louis L; Gerhard-Herman, Marie D; Kumamaru, Hiraku; Chen, Chih-Ying; Williams, Lauren A; Liu, Jun; Rothman, Andrew T; Jaff, Michael R; Seeger, John D; Benenati, James F; Schneider, Peter A; Aronow, Herbert D; Johnston, Joseph A; Brott, Thomas G; Tsai, Thomas T; White, Christopher J; Setoguchi, Soko

    2016-05-01

    Effectiveness of carotid artery stenting (CAS) relative to carotid endarterectomy (CEA) among Medicare patients has not been established. We compared effectiveness of CAS versus CEA among Medicare beneficiaries. We linked Medicare data (2000-2009) to the Society for Vascular Surgery's Vascular Registry (2005-2008) and the National Cardiovascular Data Registry's (NCDR) Carotid Artery Revascularization and Endarterectomy Registry (2006-2008/2009). Medicare patients were followed up from procedure date until death, stroke/transient ischemic attack, periprocedural myocardial infarction, or a composite end point for these outcomes. We derived high-dimensional propensity scores using registry and Medicare data to control for patient factors and adjusted for provider factors in a Cox regression model comparing CAS with CEA. Among 5254 Society for Vascular Surgery's Vascular Registry (1999 CAS; 3255 CEA) and 4055 Carotid Artery Revascularization and Endarterectomy Registry (2824 CAS; 1231 CEA) Medicare patients, CAS patients had a higher comorbidity burden and were more likely to be at high surgical risk (Society for Vascular Surgery's Vascular Registry: 96.7% versus 44.5%; Carotid Artery Revascularization and Endarterectomy Registry: 71.3% versus 44.7%). Unadjusted outcome risks were higher for CAS. Mortality risks remained elevated for CAS after adjusting for patient-level factors (hazard ratio, 1.24; 95% confidence interval, 1.06-1.46). After further adjustment for provider factors, differences between CAS and CEA were attenuated or no longer present (hazard ratio for mortality, 1.13; 95% confidence interval, 0.94-1.37). Performance was comparable across subgroups defined by sex and degree of carotid stenosis, but there was a nonsignificant trend suggesting a higher risk of adverse outcomes in older (>80) and symptomatic patients undergoing CAS. Outcomes after CAS and CEA among Medicare beneficiaries were comparable after adjusting for both patient- and provider

  20. Relationship between Common Carotid Intima-Media Thickness and Thoracic Aortic Calcification: the Multi-Ethnic Study of Atherosclerosis

    Science.gov (United States)

    Takasu, Junichiro; Budoff, Matthew J.; Katz, Ronit; Rivera, Juan J.; O'Brien, Kevin D.; Shavelle, David M.; Probstfield, Jeffrey L.; O'Leary, Daniel; Nasir, Khurram

    2009-01-01

    Background Mean maximum carotid intima-media thickness (CIMT) is associated with both coronary artery disease and cerebral thromboembolism. Thoracic aortic calcification (TAC) detected by computed tomography (CT) is also highly associated with vascular disease and cardiovascular risk. No previous study has examined the relationship between CIMT and TAC in a large patient cohort. We performed a cross-sectional study to determine whether, at baseline, there is a relationship between CIMT and CT-determined TAC score. Methods In the Multi-Ethnic Study of Atherosclerosis, the study cohort included a population based sample of four ethnic groups (Chinese, White, Hispanic and African-American) of 6814 women and men ages 45-84 years. After exclusion of 198 persons due to incomplete information, we compared results of 6616 participants with both CIMT and TAC. TAC was measured from the lower edge of the pulmonary artery bifurcation to the cardiac apex. CIMT at the common carotid artery site was represented as the mean maximal CIMT of the right and left near and far walls, respectively. Multivariable relative risk regression analysis was used to evaluate relationships between TAC and CIMT. Results The prevalence of TAC was 28% (n=1846) and the mean maximum (±SD) CIMT was 0.87±0.19 mm. A higher prevalence of TAC was noted across increasing CIMT quartiles (1st: 12%, 2nd: 21%, 3rd: 30%, 4th: 49%, P0, a higher CIMT was significantly associated with continuous TAC scores (log transformed) in the overall population as well as among all ethnic-racial groups. Conclusions Our study demonstrates that TAC is associated with increasing severity of carotid atherosclerotic burden as measured by CIMT. The combined utility of these two noninvasive measures of subclinical atherosclerosis for CVD risk assessment needs to be determined in future studies. PMID:19782983

  1. Surgical techniques and curative effect of carotid endarterectomy for carotid artery stenosis

    Directory of Open Access Journals (Sweden)

    Min HAN

    2014-02-01

    Full Text Available Objective To investigate the surgical techniques of carotid endarterectomy (CEA for treating carotid artery stenosis, in order to improve the surgical efficacy and reduce intraoperative adverse events and complications after operation. Methods Retrospective analysis was carried out on surgical data of 53 cases who were performed CEA from October 2010 to October 2013 in Department of Neurosurgery in Tianjin Huanhu Hospital. There were 39 males and 14 females, aged from 40 to 78 years old and mean age (60.34 ± 8.92 years old; the course of disease was from 2 d to 4 years. Twenty-six cases were diagnosed as right carotid stenosis, 15 cases left carotid stenosis and 12 cases double-sided carotid stenosis. Among all of those cases, 35 cases were diagnosed as moderate stenosis (30%-69%, 16 cases severe stenosis (70%-99% , and 2 cases complete occlusion. Results Among 53 patients, 50 patients underwent CEA; 2 cases underwent CEA and aneurysm clipping; one case underwent stent removal surgery and CEA because restenosis was found after carotid artery stenting (CAS. Postoperative neck CTA and fMRI showed good morphology of carotid artery, fluent blood flow and improved cerebral perfusion after operation. All of those patients were followed up for 3 to 24 months. One case died of myocardial infarction; 2 cases appeared skin numbness on the operating side of the neck, and the symptom disappeared 3 months later; one case appeared hoarseness after operation; 3 cases experienced mild transient ischemic attack (TIA and the symptom disappeared 2 months later. No case of stroke was found. Conclusions CEA is a safe and effective surgical approach to treat carotid stenosis. Correct and reasonable choices of the surgical indications and skilled surgical technique are the key to ensure the success of operation and to improve efficacy of the therapy. doi:10.3969/j.issn.1672-6731.2014.02.006Video: http://www.cjcnn.org/index.php/cjcnn/pages/view/v14n2a6

  2. Mixed-Mode Oscillations Due to a Singular Hopf Bifurcation in a Forest Pest Model

    DEFF Research Database (Denmark)

    Brøns, Morten; Desroches, Mathieu; Krupa, Martin

    2015-01-01

    In a forest pest model, young trees are distinguished from old trees. The pest feeds on old trees. The pest grows on a fast scale, the young trees on an intermediate scale, and the old trees on a slow scale. A combination of a singular Hopf bifurcation and a “weak return” mechanism, characterized...... by a small change in one of the variables, determines the features of the mixed-mode oscillations. Period-doubling and saddle-node bifurcations lead to closed families (called isolas) of periodic solutions in a bifurcation corresponding to a singular Hopf bifurcation....

  3. Radiation effects on bifurcation and dual solutions in transient natural convection in a horizontal annulus

    National Research Council Canada - National Science Library

    Luo, Kang; Yi, Hong-Liang; Tan, He-Ping

    2014-01-01

    Transitions and bifurcations of transient natural convection in a horizontal annulus with radiatively participating medium are numerically investigated using the coupled lattice Boltzmann and direct...

  4. Control of bifurcation-delay of slow passage effect by delayed self-feedback

    Science.gov (United States)

    Premraj, D.; Suresh, K.; Banerjee, Tanmoy; Thamilmaran, K.

    2017-01-01

    The slow passage effect in a dynamical system generally induces a delay in bifurcation that imposes an uncertainty in the prediction of the dynamical behaviors around the bifurcation point. In this paper, we investigate the influence of linear time-delayed self-feedback on the slow passage through the delayed Hopf and pitchfork bifurcations in a parametrically driven nonlinear oscillator. We perform linear stability analysis to derive the Hopf bifurcation point and its stability as a function of self-feedback time delay. Interestingly, the bifurcation-delay associated with Hopf bifurcation behaves differently in two different edges. In the leading edge of the modulating signal, it decreases with increasing self-feedback delay, whereas in the trailing edge, it behaves in an opposite manner. We also show that the linear time-delayed self-feedback can reduce bifurcation-delay in pitchfork bifurcation. These results are illustrated numerically and corroborated experimentally. We also propose a mechanistic explanation of the observed behaviors. In addition, we show that our observations are robust in the presence of noise. We believe that this study of interplay of two time delays of different origins will shed light on the control of bifurcation-delay and improve our knowledge of time-delayed systems.

  5. Bifurcation analysis of the transition of dune shapes under a unidirectional wind.

    Science.gov (United States)

    Niiya, Hirofumi; Awazu, Akinori; Nishimori, Hiraku

    2012-04-13

    A bifurcation analysis of dune shape transition is made. By use of a reduced model of dune morphodynamics, the Dune Skeleton model, we elucidate the transition mechanism between different shapes of dunes under unidirectional wind. It was found that the decrease in the total amount of sand in the system and/or the lateral sand flow shifts the stable state from a straight transverse dune to a wavy transverse dune through a pitchfork bifurcation. A further decrease causes wavy transverse dunes to shift into barchans through a Hopf bifurcation. These bifurcation structures reveal the transition mechanism of dune shapes under unidirectional wind.

  6. Central role of carotid body chemoreceptors in disordered breathing and cardiorenal dysfunction in chronic heart failure

    OpenAIRE

    Marcus, Noah J.; Rodrigo eDel Rio; Schultz, Harold D.

    2014-01-01

    Oscillatory breathing patterns are observed in pre-term infants, patients with cardio-renal impairment, and in otherwise healthy humans exposed to high altitude. Enhanced carotid body chemoreflex sensitivity is common to all of these populations and is thought to contribute to these abnormal patterns by destabilizing the respiratory control system. Oscillatory breathing patterns in chronic heart failure (CHF) patients are associated with greater levels of tonic and chemoreflex-evoked sympat...

  7. Two-year treatment with rosuvastatin reduces carotid intima-media thickness in HIV type 1-infected patients receiving highly active antiretroviral therapy with asymptomatic atherosclerosis and moderate cardiovascular risk.

    Science.gov (United States)

    Calza, Leonardo; Manfredi, Roberto; Colangeli, Vincenzo; Trapani, Fabio Filippo; Salvadori, Caterina; Magistrelli, Eleonora; Danese, Ilaria; Verucchi, Gabriella; Serra, Carla; Viale, Pierluigi

    2013-03-01

    Recent studies have shown that rosuvastatin significantly decreases serum levels of inflammatory biomarkers and slows progression of carotid atherosclerosis in the general population. However, there are no data about its effect on progression of atherosclerosis in HIV-infected patients. Adult patients with HIV infection, on stable antiretroviral therapy, with asymptomatic carotid atherosclerosis and hypercholesterolemia, who started a rosuvastatin treatment at 10 mg daily during the period 2007-2009 were enrolled and followed-up for 24 months. Thirty-six patients (30 males) were enrolled, with a mean age of 49 years, a mean duration of current antiretroviral therapy of 38 months, and a mean 10-year risk of myocardial infarction of 18.5%. Rosuvastatin led to a significant decrease in mean values of intima-media thickness in all extracranial carotid arteries, with the greatest magnitude observed in carotid bifurcations (a mean decrease of 18.7% in the right artery and of 21.4% in the left artery) and in internal carotid arteries (a mean decrease of 23.7% in the right artery and of 25.6% in the left artery). Moreover, there was a significant reduction in mean levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides versus respective baseline values associated with a significantly decreased mean cardiovascular risk. The treatment with rosuvastatin was well tolerated, and serious adverse events were not reported. A 24-month treatment with rosuvastatin in HIV-infected patients on highly active antiretroviral therapy (HAART) with subclinical atherosclerosis and a moderate cardiovascular risk seems to promote significantly favorable changes in carotid atherosclerosis, associated with a favorable effect on serum lipid levels and a good tolerability profile.

  8. [Intraluminal Thrombus in Internal Carotid Artery Successfully Treated with Adjuvant Anticoagulant Therapy Followed by Carotid Endarterectomy:A Case Report].

    Science.gov (United States)

    Minamide, Hisato; Hayashi, Yutaka; Ueno, Megumi

    2016-10-01

    An intraluminal thrombus in the carotid artery is relatively rare. A high frequency of perioperative symptomatic stroke has been reported in patients undergoing carotid endarterectomy, and no standard therapy has yet been developed. A 69-year-old woman, with no history of trauma, presented with ischemic stroke and mild right hemiparesis. Computed tomography and MRI showed an infarction in the left parietal region. A carotid Doppler study showed carotid stenosis on the left side. Further investigation with digital subtraction angiography confirmed significant carotid artery stenosis with an intraluminal thrombus in the left internal carotid artery. She was treated with initial intravenous anticoagulant therapy followed by carotid endarterectomy with thrombus removal 14 days after admission(subacute phase). There was no postoperative complication and she had uneventful course over 3 years of follow-up. Initial adjuvant anticoagulant therapy for symptomatic intraluminal thrombus followed by carotid revascularization is an effective surgical strategy. A meticulous surgical procedure is required to perform a carotid endarterectomy in patients with an intraluminal thrombus.

  9. Fatty Acid binding protein 4 is associated with carotid atherosclerosis and outcome in patients with acute ischemic stroke

    DEFF Research Database (Denmark)

    Holm, Sverre; Ueland, Thor; Dahl, Tuva B

    2011-01-01

    Fatty acid binding protein 4 (FABP4) has been shown to play an important role in macrophage cholesterol trafficking and associated inflammation. To further elucidate the role of FABP4 in atherogenesis in humans, we examined the regulation of FABP4 in carotid atherosclerosis and ischemic stroke....

  10. Stochastic Calculus: Application to Dynamic Bifurcations and Threshold Crossings

    Science.gov (United States)

    Jansons, Kalvis M.; Lythe, G. D.

    1998-01-01

    For the dynamic pitchfork bifurcation in the presence of white noise, the statistics of the last time at zero are calculated as a function of the noise level ∈ and the rate of change of the parameter μ. The threshold crossing problem used, for example, to model the firing of a single cortical neuron is considered, concentrating on quantities that may be experimentally measurable but have so far received little attention. Expressions for the statistics of pre-threshold excursions, occupation density, and last crossing time of zero are compared with results from numerical generation of paths.

  11. Bifurcation analysis of dengue transmission model in Baguio City, Philippines

    Science.gov (United States)

    Libatique, Criselda P.; Pajimola, Aprimelle Kris J.; Addawe, Joel M.

    2017-11-01

    In this study, we formulate a deterministic model for the transmission dynamics of dengue fever in Baguio City, Philippines. We analyzed the existence of the equilibria of the dengue model. We computed and obtained conditions for the existence of the equilibrium states. Stability analysis for the system is carried out for disease free equilibrium. We showed that the system becomes stable under certain conditions of the parameters. A particular parameter is taken and with the use of the Theory of Centre Manifold, the proposed model demonstrates a bifurcation phenomenon. We performed numerical simulation to verify the analytical results.

  12. One-dimensional map lattices: Synchronization, bifurcations, and chaotic structures

    DEFF Research Database (Denmark)

    Belykh, Vladimir N.; Mosekilde, Erik

    1996-01-01

    The paper presents a qualitative analysis of coupled map lattices (CMLs) for the case of arbitrary nonlinearity of the local map and with space-shift as well as diffusion coupling. The effect of synchronization where, independently of the initial conditions, all elements of a CML acquire uniform...... dynamics is investigated and stable chaotic time behaviors, steady structures, and traveling waves are described. Finally, the bifurcations occurring under the transition from spatiotemporal chaos to chaotic synchronization and the peculiarities of CMLs with specific symmetries are discussed....

  13. Plastic bottle oscillator: Rhythmicity and mode bifurcation of fluid flow

    OpenAIRE

    Kohira, Masahiro I.; Magome, Nobuyuki; Kitahata, Hiroyuki; Yoshikawa, Kenichi

    2007-01-01

    The oscillatory flow of water draining from an upside-down plastic bottle with a thin pipe attached to its head is studied as an example of a dissipative structure generated under far-from-equilibrium conditions. Mode bifurcation was observed in the water/air flow: no flow, oscillatory flow, and counter flow were found when the inner diameter of the thin pipe was changed. The modes are stable against perturbations. A coupled two-bottle system exhibits either in-phase or anti-phase self-synchr...

  14. Bifurcation in the chemotactic behavior of Physarum plasmodium

    Science.gov (United States)

    Shirakawa, Tomohiro; Gunji, Yukio-Pegio; Sato, Hiroshi; Tsubakino, Hiroto

    2017-07-01

    The plasmodium of true slime mold Physarum polycephalum is a unicellular and multinuclear giant amoeba. Since the cellular organism has some computational abilities, it is attracting much attention in the field of information science. However, previous studies have mainly focused on the optimization behavior of the plasmodium for a single-modality stimulus, and there are few studies on how the organism adapts to multi-modal stimuli. We stimulated the plasmodium with mixture of attractant and repellent stimuli, and we observed bifurcation in the chemotactic behavior of the plasmodium.

  15. Meta-analysis of the costs of carotid artery stenting and carotid endarterectomy.

    Science.gov (United States)

    de Vries, E E; Baldew, V G M; den Ruijter, H M; de Borst, G J

    2017-09-01

    Carotid artery stenting (CAS) is currently associated with an increased risk of 30-day stroke compared with carotid endarterectomy (CEA), whereas both interventions seem equally durable beyond the periprocedural period. Although the clinical outcomes continue to be scrutinized, there are few data summarizing the costs of both techniques. A systematic search was conducted in MEDLINE, Embase and Cochrane databases in August 2016 identifying articles comparing the costs or cost-effectiveness of CAS and CEA in patients with carotid artery stenosis. Combined overall effect sizes were calculated using random-effects models. The in-hospital costs were specified to gain insight into the main heads of expenditure associated with both procedures. The literature search identified 617 unique articles, of which five RCTs and 12 cohort studies were eligible for analysis. Costs of the index hospital admission were similar for CAS and CEA. Costs of the procedure itself were 51 per cent higher for CAS, mainly driven by the higher costs of devices and supplies, but were balanced by higher postprocedural costs of CEA. Long-term cost analysis revealed no difference in costs or quality of life after 1 year of follow-up. Hospitalization and long-term costs of CAS and CEA appear similar. Economic considerations should not influence the choice of stenting or surgery in patients with carotid artery stenosis being considered for revascularization. © 2017 BJS Society Ltd Published by John Wiley & Sons Ltd.

  16. Numerical simulation of blood flow and plaque progression in carotid-carotid bypass patient specific case.

    Science.gov (United States)

    Filipovic, Nenad; Saveljic, Igor; Nikolic, Dalibor; Milosevic, Zarko; Kovacevic, Pavle; Velicki, Lazar

    2015-01-01

    This study describes computer simulation of blood flow and plaque progression pattern in a patient who underwent surgical treatment for infected carotid prosthetic tube graft using carotid-carotid cross-over bypass. The 3D blood flow is governed by the Navier-Stokes equations, together with the continuity equation. Mass transfer within the blood lumen and through the arterial wall is coupled with the blood flow and is modelled by the convection-diffusion equation. Low-density lipoprotein (LDL) transport in lumen of the vessel is described by Kedem-Katchalsky equations. The inflammatory process is solved using three additional reaction-diffusion partial differential equations. Calculation based on a computer simulation showed that flow distribution in the left carotid artery (CA) was around 40-50% of the total flow in the right common CA. Also, the left CA had higher pressure gradient after surgical intervention. Plaque progression simulation predicted development of the atherosclerotic plaque in the position of the right common CA and the left internal CA. A novel way of atherosclerotic plaque progression modelling using computer simulation shows a potential clinical benefit with significant impact on the treatment strategy optimization.

  17. [The external carotid vein. Historical review of Paul Launay's work].

    Science.gov (United States)

    Collin, J F; Lauwers, F

    1997-08-01

    The authors, one century later, review the anatomical studies conducted by Launay, a student of Farabeuf, concerning the venous drainage of the face and neck. These studies were based on the analogy between the arterial system and the venous drainage of the external carotid territory. After describing the external carotid vein, the didactic and practical aspects of this study are emphasized.

  18. Endarterectomy or Stenting in Severe Asymptomatic Carotid Stenosis.

    Science.gov (United States)

    Mannheim, Dallit; Falah, Batla; Karmeli, Ron

    2017-05-01

    Stroke is a major cause of death in the western world, and carotid endarterectomy has been shown to be effective in treating both symptomatic and asymptomatic carotid stenosis. Carotid stenting is a relatively new form of treatment for carotid stenosis and few studies have looked specifically at asymptomatic patients. To retrospectively examine short- and long-term results in the treatment of asymptomatic carotid artery stenosis with surgery or stenting. We retrospectively collected data of all patients with asymptomatic carotid stenosis treated by carotid artery stenting or carotid endarterectomy in our department from 2006-2007. The primary endpoints were stroke, myocardial infarction, or death during the periprocedural period; or any ipsilateral stroke, restenosis, or death within 4 years after the procedure. The study comprised 409 patients who were treated by either stenting or surgery. There was a low morbidity rate in both treatment groups with no significant difference in morbidity or mortality between the treatment groups in both in the short-term as well as long-term. Both treatment methods have a low morbidity and mortality rate and should be considered for patients with few risk factors and a long life expectancy. Treatment method should be selected according to the patient's individual risk factors and imaging data.

  19. Heritability of carotid intima-media thickness : A twin study

    NARCIS (Netherlands)

    Zhao, Jinying; Cheema, Faiz A.; Bremner, J. Douglas; Goldberg, Jack; Su, Shaoyong; Snieder, Harold; Maisano, Carisa; Jones, Linda; Javed, Farhan; Murrah, Nancy; Le, Ngoc-Anh; Vaccarino, Viola

    Objective: To estimate the heritability of carotid intima-media thickness (IMT), a surrogate marker for atherosclerosis, independent of traditional coronary risk factors. Methods and results: We performed a classical twin study of carotid IMT using 98 middle-aged male twin pairs, 58 monozygotic (MZ)

  20. Carotid endarterectomy in Durban - the first 10 years | Kadwa ...

    African Journals Online (AJOL)

    This study was a prospective evaluation of the Durban experience with carotid endarterectomy over the past decade. Since 1981, 478 carotid endarterectomies have been performed in 411 patients. The majority of these patients were white men, with an average age of 60,6 years. The indication for surgery was a ...