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https://www.readbyqxmd.com/read/28636811/performance-evaluation-of-gpu-parallelization-space-time-adaptive-algorithms-and-their-combination-for-simulating-cardiac-electrophysiology
#1
Rafael S Oliveira, Bernardo M Rocha, Denise Burgarelli, Wagner Meira, Christakis Constantinides, Rodrigo Weber Dos Santos
The use of computer models as a tool for the study and understanding of the complex phenomena of cardiac electrophysiology has attained increased importance nowadays. At the same time, the increased complexity of the biophysical processes translates into complex computational and mathematical models. In order to speed up cardiac simulations and to allow more precise and realistic uses, two different techniques have been traditionally exploited: parallel computing and sophisticated numerical methods. In this work, we combine a modern parallel computing technique based on multicore and graphics processing units (GPUs), and a sophisticated numerical method based on a new space-time adaptive algorithm...
June 21, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28550650/single-breath-hold-3-d-cine-imaging-of-the-left-ventricle-using-cartesian-sampling
#2
Jens Wetzl, Michaela Schmidt, François Pontana, Benjamin Longère, Felix Lugauer, Andreas Maier, Joachim Hornegger, Christoph Forman
OBJECTIVES: Our objectives were to evaluate a single-breath-hold approach for Cartesian 3-D CINE imaging of the left ventricle with a nearly isotropic resolution of [Formula: see text] and a breath-hold duration of [Formula: see text]19 s against a standard stack of 2-D CINE slices acquired in multiple breath-holds. Validation is performed with data sets from ten healthy volunteers. MATERIALS AND METHODS: A Cartesian sampling pattern based on the spiral phyllotaxis and a compressed sensing reconstruction method are proposed to allow 3-D CINE imaging with high acceleration factors...
May 26, 2017: Magma
https://www.readbyqxmd.com/read/28536896/helical-distribution-of-hypertrophy-in-patients-with-hypertrophic-cardiomyopathy-prevalence-and-clinical-implications
#3
Dafne Viliani, Eduardo Pozo, Norma Aguirre, Alberto Cecconi, María J Olivera, Paloma Caballero, Luis J Jiménez-Borreguero, Fernando Alfonso
Recently a novel pattern of helical distribution of hypertrophy has been described in patients with hypertrophic cardiomyopathy (HCM). Our aim was to determine its prevalence and potential implications in an unselected cohort. One-hundred- and eight consecutive patients diagnosed with HCM by cardiac magnetic resonance (CMR) were included (median clinical follow up of 1718 days). All clinical and complementary test information was prospectively collected. The presence of a helical pattern was assessed by a simple measurement of the maximal left ventricle (LV) wall thickness (LVWT) for each of the 17 classical LV segments and it was classified in one of three types according to its extension...
May 23, 2017: International Journal of Cardiovascular Imaging
https://www.readbyqxmd.com/read/28465995/asymptomatic-left-ventricular-dissection
#4
Andras Nagy, Zafar Iqbal Khan, Saeed Yahya Al Sayari, Abdelaziz Sabry Aboushaeshae, Rathibala Natarajan
Intramyocardial dissection is an uncommon complication of myocardial infarction, chest trauma, and percutaneous intervention. It is usually caused by a hemorrhagic dissection among the spiral myocardial fibers. Carries high mortality and there is still uncertainty regarding invasive or conservative management. We present a case of the left ventricular dissection discovered incidentally.
April 2017: Journal of Cardiovascular Echography
https://www.readbyqxmd.com/read/28444501/validation-of-numerical-simulation-methods-in-aortic-arch-using-4d-flow-mri
#5
Shohei Miyazaki, Keiichi Itatani, Toyoki Furusawa, Teruyasu Nishino, Masataka Sugiyama, Yasuo Takehara, Satoshi Yasukochi
Computational fluid dynamics (CFD) are the gold standard in studying blood flow dynamics. However, CFD results are dependent on the boundary conditions and the computation model. The purpose of this study was to validate CFD methods using comparison with actual measurements of the blood flow vector obtained with four-dimensional (4D) flow magnetic resonance imaging (MRI). 4D Flow MRI was performed on a healthy adult and a child with double-aortic arch. The aortic lumen was segmented to visualize the blood flow...
April 25, 2017: Heart and Vessels
https://www.readbyqxmd.com/read/28297843/spiral-wave-dynamics-in-a-mathematical-model-of-human-ventricular-tissue-with-myocytes-and-purkinje-fibers
#6
Alok Ranjan Nayak, A V Panfilov, Rahul Pandit
We present systematic numerical studies of the possible effects of the coupling of human endocardial and Purkinje cells at cellular and two-dimensional tissue levels. We find that the autorhythmic-activity frequency of the Purkinje cell in a composite decreases with an increase in the coupling strength; this can even eliminate the autorhythmicity. We observe a delay between the beginning of the action potentials of endocardial and Purkinje cells in a composite; such a delay increases as we decrease the diffusive coupling, and eventually a failure of transmission occurs...
February 2017: Physical Review. E
https://www.readbyqxmd.com/read/28213506/role-of-apamin-sensitive-calcium-activated-small-conductance-potassium-currents-on-the-mechanisms-of-ventricular-fibrillation-in-pacing-induced-failing-rabbit-hearts
#7
Dechun Yin, Yu-Cheng Hsieh, Wei-Chung Tsai, Adonis Zhi-Yang Wu, Zhaolei Jiang, Yi-Hsin Chan, Dongzhu Xu, Na Yang, Changyu Shen, Zhenhui Chen, Shien-Fong Lin, Peng-Sheng Chen, Thomas H Everett
BACKGROUND: Ventricular fibrillation (VF) during heart failure is characterized by stable reentrant spiral waves (rotors). Apamin-sensitive small-conductance calcium-activated potassium currents (IKAS) are heterogeneously upregulated in failing hearts. We hypothesized that IKAS influences the location and stability of rotors during VF. METHODS AND RESULTS: Optical mapping was performed on 9 rabbit hearts with pacing-induced heart failure. The epicardial right ventricular and left ventricular surfaces were simultaneously mapped in a Langendorff preparation...
February 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28129401/impact-of-bounded-noise-and-rewiring-on-the-formation-and-instability-of-spiral-waves-in-a-small-world-network-of-hodgkin-huxley-neurons
#8
Yuangen Yao, Haiyou Deng, Chengzhang Ma, Ming Yi, Jun Ma
Spiral waves are observed in the chemical, physical and biological systems, and the emergence of spiral waves in cardiac tissue is linked to some diseases such as heart ventricular fibrillation and epilepsy; thus it has importance in theoretical studies and potential medical applications. Noise is inevitable in neuronal systems and can change the electrical activities of neuron in different ways. Many previous theoretical studies about the impacts of noise on spiral waves focus an unbounded Gaussian noise and even colored noise...
2017: PloS One
https://www.readbyqxmd.com/read/28115510/abnormal-wave-reflections-and-left-ventricular-hypertrophy-late-after-coarctation-of-the-aorta-repair
#9
Michael A Quail, Rebekah Short, Bejal Pandya, Jennifer A Steeden, Abbas Khushnood, Andrew M Taylor, Patrick Segers, Vivek Muthurangu
Patients with repaired coarctation of the aorta are thought to have increased afterload due to abnormalities in vessel structure and function. We have developed a novel cardiovascular magnetic resonance protocol that allows assessment of central hemodynamics, including central aortic systolic blood pressure, resistance, total arterial compliance, pulse wave velocity, and wave reflections. The main study aims were to (1) characterize group differences in central aortic systolic blood pressure and peripheral systolic blood pressure, (2) comprehensively evaluate afterload (including wave reflections) in the 2 groups, and (3) identify possible biomarkers among covariates associated with elevated left ventricular mass (LVM)...
March 2017: Hypertension
https://www.readbyqxmd.com/read/28066662/-spiral-stenting-creating-a-subintimal-neo-luminal-helix-around-a-massively-calcified-ostial-chronic-total-occlusion-of-the-right-coronary-artery-in-a-patient-with-recurrent-ventricular-tachycardia
#10
Kambis Mashayekhi, Zivile Valuckiene, Hans Neuser, Marlon Walter, Wolfgang Gappmaier, Thomas Kaiser, Franz-Josef Neumann, Ibrahim Akin, Michael Behnes
This case report describes a successful percutaneous coronary intervention (PCI) of a severely calcified aorto-ostial chronic total occlusion (CTO) of the right coronary artery (RCA). The lesion was treated by a retrograde approach implementing long spiral subintimal wire tracking and final coronary stenting creating a subintimal neo-luminal helix around the natively occluded RCA. After 6 months of follow-up valuable angiographic results were proven.
November 2016: Journal of Thoracic Disease
https://www.readbyqxmd.com/read/28055859/right-ventricular-strain-torsion-and-dyssynchrony-in-healthy-subjects-using-3d-spiral-cine-dense-magnetic-resonance-imaging
#11
Jonathan D Suever, Gregory J Wehner, Linyuan Jing, David K Powell, Sean M Hamlet, Jonathan D Grabau, Dimitri Mojsejenko, Kristin N Andres, Christopher M Haggerty, Brandon K Fornwalt
Mechanics of the left ventricle (LV) are important indicators of cardiac function. The role of right ventricular (RV) mechanics is largely unknown due to the technical limitations of imaging its thin wall and complex geometry and motion. By combining 3D Displacement Encoding with Stimulated Echoes (DENSE) with a post-processing pipeline that includes a local coordinate system, it is possible to quantify RV strain, torsion, and synchrony. In this study, we sought to characterize RV mechanics in 50 healthy individuals and compare these values to their LV counterparts...
May 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28011584/effect-of-anisotropy-on-ventricular-vulnerability-to-unidirectional-block-and-reentry-by-single-premature-stimulation-during-normal-sinus-rhythm-in-rat-heart
#12
S Rossi, A Buccarello, P R Ershler, R L Lux, S Callegari, D Corradi, L Carnevali, A Sgoifo, M Miragoli, E Musso, E Macchi
Single high-intensity premature stimuli when applied to the ventricles during ventricular drive of an ectopic site, as in Winfree's "pinwheel experiment," usually induce reentry arrhythmias in the normal heart, while single low-intensity stimuli barely do. Yet ventricular arrhythmia vulnerability during normal sinus rhythm remains largely unexplored. With a view to define the role of anisotropy on ventricular vulnerability to unidirectional conduction block and reentry, we revisited the pinwheel experiment with reduced constraints in the in situ rat heart...
March 1, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/27943326/technologies-for-prolonging-cardiac-implantable-electronic-device-longevity
#13
REVIEW
Ernest W Lau
Prolonged longevity of cardiac implantable electronic devices (CIEDs) is needed not only as a passive response to match the prolonging life expectancy of patient recipients, but will also actively prolong their life expectancy by avoiding/deferring the risks (and costs) associated with device replacement. CIEDs are still exclusively powered by nonrechargeable primary batteries, and energy exhaustion is the dominant and an inevitable cause of device replacement. The longevity of a CIED is thus determined by the attrition rate of its finite energy reserve...
January 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/27805726/a-micropatterned-human-pluripotent-stem-cell-based-ventricular-cardiac-anisotropic-sheet-for-visualizing-drug-induced-arrhythmogenicity
#14
Angie M Y Shum, Hui Che, Andy On-Tik Wong, Chenzi Zhang, Hongkai Wu, Camie W Y Chan, Kevin Costa, Michelle Khine, Chi-Wing Kong, Ronald A Li
A novel cardiomimetic biohybrid material, termed as the human ventricular cardiac anisotropic sheet (hvCAS) is reported. Well-characterized human pluripotent stem-cell-derived ventricular cardiomyocytes are strategically aligned to reproduce key electrophysiological features of native human ventricle, which, along with specific selection criteria, allows for a direct visualization of arrhythmic spiral re-entry and represents a revolutionary tool to assess preclinical drug-induced arrhythmogenicity.
January 2017: Advanced Materials
https://www.readbyqxmd.com/read/27780271/quantification-of-coupled-stiffness-and-fiber-orientation-remodeling-in-hypertensive-rat-right-ventricular-myocardium-using-3d-ultrasound-speckle-tracking-with-biaxial-testing
#15
Dae Woo Park, Andrea Sebastiani, Choon Hwai Yap, Marc A Simon, Kang Kim
Mechanical and structural changes of right ventricular (RV) in response to pulmonary hypertension (PH) are inadequately understood. While current standard biaxial testing provides information on the mechanical behavior of RV tissues using surface markers, it is unable to fully assess structural and mechanical properties across the full tissue thickness. In this study, the mechanical and structural properties of normotensive and pulmonary hypertension right ventricular (PHRV) myocardium through its full thickness were examined using mechanical testing combined with 3D ultrasound speckle tracking (3D-UST)...
2016: PloS One
https://www.readbyqxmd.com/read/27760439/pneumatic-distension-of-ventricular-mural-architecture-validated-histologically
#16
M C Burg, P Lunkenheimer, P Niederer, C Brune, K Redmann, M Smerup, U Spiegel, F Becker, D Maintz, W Heindel, R H Anderson
Purpose: There are ongoing arguments as to how cardiomyocytes are aggregated together within the ventricular walls. We used pneumatic distension through the coronary arteries to exaggerate the gaps between the aggregated cardiomyocytes, analyzing the pattern revealed using computed tomography, and validating our findings by histology. Methods: We distended 10 porcine hearts, arresting 4 in diastole by infusion of cardioplegic solutions, and 4 in systole by injection of barium chloride. Mural architecture was revealed by computed tomography, measuring also the angulations of the long chains of cardiomyocytes...
November 2016: RöFo: Fortschritte Auf Dem Gebiete der Röntgenstrahlen und der Nuklearmedizin
https://www.readbyqxmd.com/read/27751289/apical-hypertrophic-cardiomyopathy-with-hemodynamically-unstable-ventricular-arrhythmia-atypical-presentation
#17
Hemant Chaturvedi, Rudra Dev Pandey, Krishna Kumar Sharma, Jitendra Singh Makkar, Sanjeev K Sharma
We present a patient with asymptomatic apical hypertrophic cardiomyopathy (AHCM) who recently developed cardiac arrhythmias, and shortly discuss the diagnostic modalities, differential diagnosis, and treatment strategy for this condition. AHCM is a rare form of hypertrophic cardiomyopathy, which usually involves the apex of the left ventricle. AHCM can occur with varied presentations such as chest pain, palpitations, dyspnea, syncope, atrial fibrillation, myocardial infarction, embolic events, ventricular fibrillation, and congestive heart failure...
September 2016: Indian Heart Journal
https://www.readbyqxmd.com/read/27702850/traditional-and-novel-electrocardiographic-conduction-and-repolarization-markers-of-sudden-cardiac-death
#18
Gary Tse, Bryan P Yan
Sudden cardiac death, frequently due to ventricular arrhythmias, is a significant problem globally. Most affected individuals do not arrive at hospital in time for medical treatment. Therefore, there is an urgent need to identify the most-at-risk patients for insertion of prophylactic implantable cardioverter defibrillators. Clinical risk markers derived from electrocardiography are important for this purpose. They can be based on repolarization, including corrected QT (QTc) interval, QT dispersion (QTD), interval from the peak to the end of the T-wave (Tpeak - Tend), (Tpeak - Tend)/QT, T-wave alternans (TWA), and microvolt TWA...
May 1, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/27613549/the-right-ventricle-interaction-with-the-pulmonary-circulation
#19
REVIEW
Michael R Pinsky
The primary role of the right ventricle (RV) is to deliver all the blood it receives per beat into the pulmonary circulation without causing right atrial pressure to rise. To the extent that it also does not impede left ventricular (LV) filling, cardiac output responsiveness to increased metabolic demand is optimized. Since cardiac output is a function of metabolic demand of the body, during stress and exercise states the flow to the RV can vary widely. Also, instantaneous venous return varies widely for a constant cardiac output as ventilatory efforts alter the dynamic pressure gradient for venous return...
September 10, 2016: Critical Care: the Official Journal of the Critical Care Forum
https://www.readbyqxmd.com/read/27599620/an-interactive-videogame-designed-to-improve-respiratory-navigator-efficiency-in-children-undergoing-cardiovascular-magnetic-resonance
#20
Sean M Hamlet, Christopher M Haggerty, Jonathan D Suever, Gregory J Wehner, Jonathan D Grabau, Kristin N Andres, Moriel H Vandsburger, David K Powell, Vincent L Sorrell, Brandon K Fornwalt
BACKGROUND: Advanced cardiovascular magnetic resonance (CMR) acquisitions often require long scan durations that necessitate respiratory navigator gating. The tradeoff of navigator gating is reduced scan efficiency, particularly when the patient's breathing patterns are inconsistent, as is commonly seen in children. We hypothesized that engaging pediatric participants with a navigator-controlled videogame to help control breathing patterns would improve navigator efficiency and maintain image quality...
September 6, 2016: Journal of Cardiovascular Magnetic Resonance
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