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Cardiac mechanics

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https://www.readbyqxmd.com/read/28227773/whole-heart-modeling-spatiotemporal-dynamics-of-electrical-wave-conduction-and-propagation
#1
Hui Yang, Yun Chen, Fabio M Leonelli, Hui Yang, Yun Chen, Fabio M Leonelli, Hui Yang, Fabio M Leonelli, Yun Chen
Cardiac electrical activities are varying in both space and time. Human heart consists of a fractal network of muscle cells, Purkinje fibers, arteries and veins. Whole-heart modeling of electrical wave conduction and propagation involves a greater level of complexity. Our previous work developed a computer model of the anatomically realistic heart and simulated the electrical conduction with the use of cellular automata. However, simplistic assumptions and rules limit its ability to provide an accurate approximation of real-world dynamics on the complex heart surface, due to sensitive dependence of nonlinear dynamical systems on initial conditions...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227661/parameter-optimization-of-pseudo-rigid-body-models-of-mri-actuated-catheters
#2
Tipakorn Greigarn, Taoming Liu, M Cenk Cavusoglu, Tipakorn Greigarn, Taoming Liu, M Cenk Cavusoglu, Taoming Liu, Tipakorn Greigarn, M Cenk Cavusoglu
Simulation and control of a system containing compliant mechanisms such as cardiac catheters often incur high computational costs. One way to reduce the costs is to approximate the mechanisms with Pseudo-Rigid-Body Models (PRBMs). A PRBM generally consists of rigid links connected by spring-loaded revolute joints. The lengths of the rigid links and the stiffnesses of the springs are usually chosen to minimize the tip deflection differences between the PRBM and the compliant mechanism. In most applications, only the relationship between end load and tip deflection is considered...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227618/non-invasive-cardiac-output-monitoring-in-pharmacology-a-plethysmographie-solution-in-rats
#3
Timothe Flenet, Julie Fontecave-Jallon, Stephane Tanguy, Francois Boucher, Pierre Baconnier, Pierre-Yves Gumery, Timothe Flenet, Julie Fontecave-Jallon, Stephane Tanguy, Francois Boucher, Pierre Baconnier, Pierre-Yves Gumery, Pierre-Yves Gumery, Pierre Baconnier, Stephane Tanguy, Julie Fontecave-Jallon, Francois Boucher, Timothe Flenet
Cardiovascular monitoring is of great importance in pharmacology but there is a lack of convenient non-invasive alternatives. Hence, we aim to evaluate the relevance of inductive plethysmography (IP) in preclinical cardiac studies. An IP system was specifically designed for rat. Its evaluation carried out using a mechanical test bench has shown appropriate instrumental performances for cardiac monitoring in rats. Measurements were also performed during a volume overload hemodynamic challenge in vivo in rats...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227605/an-accelerometer-based-system-to-measure-myocardial-performance-index-during-stress-testing
#4
Anh Dinh, Francis M Bui, Tam Nguyen, Anh Dinh, Francis M Bui, Tam Nguyen, Tam Nguyen, Anh Dinh, Francis M Bui
Stress testing is used to measure the performance of the heart in an elevated stress state, in order to monitor or diagnose certain heart problems. Many measurements can be used to determine the performance of the heart, with the Tei index being the measurement of interest in this work. The Tei index has been used as a reliable method to evaluate systolic and diastolic performance, as it overcomes some limitations of the classical echocardiographic indices. It is calculated based on the time intervals derived from echocardiography...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227463/hemodynamic-effects-of-synchronizing-an-intra-aortic-vad-in-reverse-rotation-control-with-left-ventricle-a-mock-loop-study
#5
Yaxin Wang, P Alex Smith, Daniel L Timms, Po-Lin Hsu, Richard A McMahon, Yaxin Wang, P Alex Smith, Daniel L Timms, Po-Lin Hsu, Richard A McMahon, Richard A McMahon, Daniel L Timms, Po-Lin Hsu, Yaxin Wang, P Alex Smith
The IntraVAD is an intra-aortic left ventricular assist device (LVAD) to be located in the ascending aorta. In order to enhance unloading and promote coronary flow for the left ventricle (LV), an operating mechanism, reverse-rotation control (RRc) mode, has been developed for the IntraVAD and tested in vitro in a mock circulation loop (MCL). The RRc mode consists of forward rotation (FR) and reverse rotation (RR). The synchronization between the IntraVAD and the LV was studied to offload the ventricle more effectively and to improve myocardial perfusion...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227426/characterization-of-patient-specific-biventricular-mechanics-in-heart-failure-with-preserved-ejection-fraction-hyperelastic-warping
#6
Hua Zou, Xiaodan Zhao, Xi Ce, Lik Chuan Lee, Martin Genet, Yi Su, Rusan Tan, Liang Zhong, Hua Zou, Xiaodan Zhao, Xi Ce, Lik Chuan Lee, Martin Genet, Yi Su, Rusan Tan, Liang Zhong, Rusan Tan, Martin Genet, Hua Zou, Lik Chuan Lee, Yi Su, Liang Zhong, Xiaodan Zhao, Xi Ce
Heart failure with preserved ejection fraction (HFPEF) is considered as a major public health problem. Traditionally, HFPEF is diagnosed based on a "normal" EF, but the studies have explored the potential role of left ventricular mechanics. Furthermore, right ventricular mechanics and bi-ventricular interaction in HFPEF is currently not well understood. In this study, we aim to develop a framework using a hyperelastic warping approach to quantify bi-ventricular and septum strains from cardiac magnetic resonance (CMR) images...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227423/dynamic-mapping-of-ventricular-function-from-cardiovascular-magnetic-resonance-imaging
#7
Maria Panayiotou, Peter Mountney, Alexander Brost, Daniel Toth, Tom Jackson, Jonathan M Behar, Christopher A Rinaldi, R James Housden, Kawal S Rhode, Maria Panayiotou, Peter Mountney, Alexander Brost, Daniel Toth, Tom Jackson, Jonathan M Behar, Christopher A Rinaldi, R James Housden, Kawal S Rhode, Alexander Brost, Tom Jackson, Maria Panayiotou, Christopher A Rinaldi, Jonathan M Behar, R James Housden, Kawal S Rhode, Daniel Toth, Peter Mountney
Heart failure is associated with substantial mortality and morbidity and remains the most common diagnosis in older patients. Based on experimental electrophysiologic studies, cardiac resynchronization therapy (CRT) for heart failure results in a maximum resynchronization effect when applied to the most delayed left ventricular (LV) site. Current clinical practice is to identify the optimal site using separate visualisation of scar and activation information. These must be mentally mapped into 3D, which is challenging and time-consuming for the electrophysiologist...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227286/indirect-measurement-of-the-carotid-arterial-pressure-from-vibrocardiographic-signal-calibration-of-the-waveform-and-comparison-with-photoplethysmographic-signal
#8
L Casacanditella, G Cosoli, S Casaccia, E P Tomasini, L Scalise, L Casacanditella, G Cosoli, S Casaccia, E P Tomasini, L Scalise, G Cosoli, S Casaccia, E P Tomasini, L Casacanditella, L Scalise
The detection of arterial Blood Pressure waveform provides important information about the subject health status. Laser Doppler Vibrometry (LDV) is a non-contact technique with high sensitivity able to detect mechanical movements of the arterial wall; several previous studies have shown that LDV is able to characterize cardiac activity. Photoplethysmogram (PPG) quantifies the digital volume artery pulse, which has been demonstrated to be closely related to the pressure signal measured by an arterial tonometer...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227126/cardiac-muscle-energetics-improved-normalisation-of-heat-using-optical-coherence-tomography
#9
Ming L Cheuk, Callum M Johnston, June-Chiew Han, Denis S Loiselle, Poul M F Nielsen, Andrew J Taberner, Ming L Cheuk, Callum M Johnston, June-Chiew Han, Denis S Loiselle, Poul M F Nielsen, Andrew J Taberner, June-Chiew Han, Callum M Johnston, Poul M F Nielsen, Ming L Cheuk, Denis S Loiselle, Andrew J Taberner
Heat liberated from isolated cardiac muscle has been used to inform us of thermo-mechanical processes that occur during a contraction. However, for comparisons between different samples to be useful, the heat output needs to be normalized to volume. We have implemented an optical coherence tomograph (OCT), together with a flow-through calorimeter, to accurately determine both muscle volume and heat in the same measurement chamber. The heat rate for multiple stimulation frequencies were recorded and normalized to the volume captured by the OCT...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227084/development-of-data-acquisition-components-for-simultaneous-recording-of-3d-epicardial-and-surface-ecg-signals-in-the-langendorff-perfusion-apparatus
#10
Ryan Wade Selby, Anup Jonchhe, Chen Kaplan, Coeli M Lopes, Behnaz Ghoraani, Ryan Wade Selby, Anup Jonchhe, Chen Kaplan, Coeli M Lopes, Behnaz Ghoraani, Chen Kaplan, Behnaz Ghoraani, Anup Jonchhe, Coeli M Lopes, Ryan Wade Selby
Sudden Cardiac Death (SCD) claims 7 million lives per year. The importance of myocardial electrogram (EGM) repolarization alternans and surface electrocardiogram (ECG) T-wave alternans is gaining traction for understanding the underlying SCD mechanisms. However, the relationship between the 3D spatial distribution of myocardial EGMs and surface ECG with respect to SCD has yet to be investigated. To make this happen, a modified data acquisition system has been developed and fabricated in conjunction with the Langendorff perfusion system to enable simultaneous recording and analysis of the 3D spatial distribution of myocardial EGMs and the surface ECG...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226918/gyrocardiography-a-new-non-invasive-approach-in-the-study-of-mechanical-motions-of-the-heart-concept-method-and-initial-observations
#11
Mojtaba Jafari Tadi, Eero Lehtonen, Mikko Pankaala, Antti Saraste, Tuija Vasankari, Mika Teras, Tero Koivisto, Mojtaba Jafari Tadi, Eero Lehtonen, Mikko Pankaala, Antti Saraste, Tuija Vasankari, Mika Teras, Tero Koivisto, Eero Lehtonen, Mojtaba Jafari Tadi, Mika Teras, Antti Saraste, Tuija Vasankari, Mikko Pankaala, Tero Koivisto
The pumping action of the heart is performed by contraction of the myocardium fibers. We present a non-invasive technique named gyrocardiography (GCG) that comprises a sensor of angular motion, gyroscope, configured to obtain three-dimensional angular velocity signals. A tri-axial micro electromechanical (MEMS) gyroscope sensor was attached to the surface of the chest to obtain gyrocardiogram. Color-coded Doppler tissue imaging (DTI) was recorded simultaneously and synchronized with the GCG in an off-line analysis...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226541/combined-reconstruction-of-atrial-morphology-and-paracardial-fat-depositions-to-study-remodeling-in-atrial-fibrillation
#12
N Popovic, P Haemers, R Willems, P Claus, N Popovic, P Haemers, R Willems, P Claus, P Claus, P Haemers, N Popovic, R Willems
Atrial fibrillation (AF) is the most frequent sustained cardiac arrhythmia. AF is shown to be a progressive disease, which is strongly associated with important structural (morphological and histological), electrical and mechanical remodeling of the left atrium (LA). Adipose tissue accumulation has been shown to be a risk factor in AF. We set out to explore the connection between adipose tissue coverage of the LA surface, for both the complete LA and specific regions and the progression of AF. In this study we propose a methodology to study the regional coverage of the left-atrial wall with adipose tissue based on magnetic resonance data...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226463/cardiac-katp-channel-modulation-by-16hz-magnetic-fields-a-theoretical-study
#13
Yuval Aharonovich, Mickey Scheinowitz, Sharon Zlochiver, Yuval Aharonovich, Mickey Scheinowitz, Sharon Zlochiver, Yuval Aharonovich, Sharon Zlochiver, Mickey Scheinowitz
Heart exposure to 16Hz magnetic fields (MFs) was shown to be cardio-protective for diseased hearts; still, the mechanism of this effect is unknown. We hypothesize that a possible one mechanism is an increased trans-membrane KATP channel open probability due to modulation of the degree of dissociation between K(+) ions, having a resonance frequency of 16Hz, and the channel selectivity filter. The Fan-Makielski Markovian KATP channel model was adopted, and the MF bio-effect was manifested by modulating the open probability of the channel using the predictive MF bio-effect parameter based on Binhi's quantum mechanics model...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226462/effects-and-underlying-mechanisms-of-refractory-period-pacing-on-repolarization-dynamics-in-the-human-heart
#14
Diogo Santos, Michele Orini, Xin Zhou, Alfonso Bueno-Orovio, Ben Hanson, Peter Taggart, Martin Hayward, Blanca Rodriguez, Pier Lambiase, Diogo Santos, Michele Orini, Xin Zhou, Alfonso Bueno-Orovio, Ben Hanson, Peter Taggart, Martin Hayward, Blanca Rodriguez, Pier Lambiase, Ben Hanson, Diogo Santos, Martin Hayward, Pier Lambiase, Alfonso Bueno-Orovio, Blanca Rodriguez, Michele Orini, Xin Zhou, Peter Taggart
Repolarization alternans is related to the initiation of life threatening cardiac arrhythmias. Experimental and computational studies suggest that the abolishment of alternans using dynamic pacing protocols may prevent abnormal heart rhythms. In a recent animal study, refractory period pacing (RPP) on every other beat has shown promising results in alternans reduction. However, the cellular mechanisms underlying this therapy and its efficiency in human patients remain unclear. In this study, in vivo unipolar electrograms acquired during RPP from 240 epicardial sites from one patient were analysed...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226461/role-of-cytosolic-calcium-diffusion-in-cardiac-purkinje-cells
#15
Bijay Limbu, Kushal Shah, Makarand Deo, Bijay Limbu, Kushal Shah, Makarand Deo, Bijay Limbu, Makar Deo, Kushal Shah
The Cardiac Purkinje cells (PCs) exhibit distinct calcium (Ca(2)+) homeostasis than that in ventricular myocytes (VMs). Due to lack of t-tubules in PCs, the Ca(2)+ ions entering the cell have to diffuse through the cytoplasm to reach the sarcoplasmic reticulum (SR) before triggering Ca(2)+-induced-Ca(2)+-release (CICR). In recent experimental studies PCs have been shown to be more susceptible to action potential (AP) abnormalities than the VMs, however the exact mechanisms are poorly understood. In this study, we utilize morphologically realistic detailed biophysical mathematical model of a murine PC to systematically examine the role intracellular Ca(2)+ diffusion in the APs of PCs...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28225640/absolute-delay-multiphase-reconstruction-reduces-prosthetic-valve-related-and-atrial-fibrillation-related-artifacts-at-cardiac-ct
#16
Young Joo Suh, Dong Jin Im, Yoo Jin Hong, Hye-Jeong Lee, Jin Hur, Byoung Wook Choi, Young Jin Kim
OBJECTIVE: The objective of our study was to compare the image quality of cardiac CT images of mechanical valves in patients with irregular heart rates (HRs) using absolute-delay multiphase reconstruction versus relative-delay multiphase reconstruction. MATERIALS AND METHODS: A total of 26 patients with 40 mechanical valves who had atrial fibrillation during CT were included. The image quality of the CT scans was assessed for the subvalvular and valvular regions on a 4-point scale...
February 22, 2017: AJR. American Journal of Roentgenology
https://www.readbyqxmd.com/read/28225183/protective-effects-of-araloside-c-against-myocardial-ischaemia-reperfusion-injury-potential-involvement-of-heat-shock-protein-90
#17
Min Wang, Yu Tian, Yu-Yang Du, Gui-Bo Sun, Xu-Dong Xu, Hai Jiang, Hui-Bo Xu, Xiang-Bao Meng, Jing-Yi Zhang, Shi-Lan Ding, Miao-di Zhang, Ming-Hua Yang, Xiao-Bo Sun
The present study was designed to investigate whether Araloside C, one of the major triterpenoid compounds isolated from Aralia elata known to be cardioprotective, can improve heart function following ischaemia/reperfusion (I/R) injury and elucidate its underlying mechanisms. We observed that Araloside C concentration-dependently improved cardiac function and depressed oxidative stress induced by I/R. Similar protection was confirmed in isolated cardiomyocytes characterized by maintaining Ca(2+) transients and cell shortening against I/R...
February 22, 2017: Journal of Cellular and Molecular Medicine
https://www.readbyqxmd.com/read/28225063/targeted-inhibition-of-focal-adhesion-kinase-attenuates-cardiac-fibrosis-and-preserves-heart-function-in-adverse-cardiac-remodeling
#18
Jie Zhang, Guangpu Fan, Hui Zhao, Zhiwei Wang, Fei Li, Peide Zhang, Jing Zhang, Xu Wang, Wei Wang
Cardiac fibrosis in post-myocardial infarction (MI), seen in both infarcted and non-infarcted myocardium, is beneficial to the recovery of heart function. But progressively pathological fibrosis impairs ventricular function and leads to poor prognosis. FAK has recently received attention as a potential mediator of fibrosis, our previous study reported that pharmacological inhibition of FAK can attenuate cardiac fibrosis in post MI models. However, the long-term effects on cardiac function and adverse cardiac remodelling were not clearly investigated...
February 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28225023/traditional-chinese-medicine-suppresses-left-ventricular-hypertrophy-by-targeting-extracellular-signal-regulated-kinases-signaling-pathway-in-spontaneously-hypertensive-rats
#19
Xingjiang Xiong, Xiaochen Yang, Lian Duan, Wei Liu, Yun Zhang, Yongmei Liu, Pengqian Wang, Shengjie Li, Xiaoke Li
Chinese herbal medicine Bu-Shen-Jiang-Ya decoction (BSJYD) is reported to be beneficial for hypertension. Over expression of extracellular signal regulated kinases (ERK) pathway plays an important role in left ventricular hypertrophy (LVH). This study aimed to observe effects of BSJYD on LVH in spontaneously hypertensive rats (SHRs) and explore its possible mechanism on regulation of ERK pathway. Sixty 12-week-old SHRs were randomly allocated into 5 groups: BSJYD high dose group, middle dose group, low dose group, captopril group, and control group...
February 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28224424/dynamic-characteristic-mechanism-of-atrial-septal-defect-using-real-time-three-dimensional-echocardiography-and-evaluation-of-right-ventricular-functions
#20
Gao-Wa Sharen, Jun Zhang, Chuan Qin, Qing Lv
The dynamic characteristics of the area of the atrial septal defect (ASD) were evaluated using the technique of real-time three-dimensional echocardiography (RT 3DE), the potential factors responsible for the dynamic characteristics of the area of ASD were observed, and the overall and local volume and functions of the patients with ASD were measured. RT 3DE was performed on the 27 normal controls and 28 patients with ASD. Based on the three-dimensional data workstations, the area of ASD was measured at P wave vertex, R wave vertex, T wave starting point, and T wave terminal point and in the T-P section...
February 2017: Journal of Huazhong University of Science and Technology. Medical Sciences
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