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Cardiac electrophysiology

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https://www.readbyqxmd.com/read/28436840/a-parametric-computational-model-of-the-action-potential-of-pacemaker-cells
#1
Weiwei Ai, Nitish Patel, Partha Roop, Avinash Malik, Sidharta Andalam, Eugene Yip, Nathan Allen, Mark Trew
OBJECTIVE: A flexible, efficient and verifiable pacemaker cell model is essential to the design of real-time virtual hearts that can be used for closed-loop validation of cardiac devices. A new parametric model of pacemaker action potential is developed to address this need. METHODS: The action potential phases are modeled using hybrid automaton (HA) with one piecewise-linear continuous variable. The model can capture ratedependent dynamics, such as action potential duration (APD) restitution, conduction velocity (CV) restitution, and overdrive suppression by incorporating non-linear update functions...
April 24, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28430892/anti-arrhythmic-potential-of-the-late-sodium-current-inhibitor-gs-458967-in-murine-scn5a-1798insd-and-human-scn5a-1795insd-ipsc-derived-cardiomyocytes
#2
Vincent Portero, Simona Casini, Maaike Hoekstra, Arie O Verkerk, Isabella Mengarelli, Luiz Belardinelli, Sridharan Rajamani, Arthur A M Wilde, Connie R Bezzina, Marieke W Veldkamp, Carol Ann Remme
AIM: Selective inhibition of cardiac late sodium current (INaL) is an emerging target in the treatment of ventricular arrhythmias. We investigated the electrophysiological effects of GS-458967 (GS967), a potent, selective inhibitor of INaL, in an overlap syndrome model of both gain and loss of sodium channel function, comprising cardiomyocytes derived from both human SCN5A-1795insD+/- induced pluripotent stem cells (hiPSC-CMs) and mice carrying the homologous mutation Scn5a-1798insD+/-...
April 18, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28430113/should-physicians-instead-of-industry-representatives-be-the-main-actor-of-cardiac-implantable-electronic-device-follow-up-super-follow-up
#3
Çağın Mustafa Üreyen, Cem Yunus Baş, İsa Öner Yüksel, Görkem Kuş, Göksel Çağırcı, Şakir Arslan
OBJECTIVE: This retrospective study sought to research the adequacy of the follow-up and optimization of cardiac implantable electronic devices (CIEDs) performed by industry representatives. METHODS: A total of 403 consecutive patients (35% females; median age, 67 years; age range 18-97 years) with either pacemakers (n=246), implantable cardioverter-defibrillators (ICDs), (n=117) or cardiac resynchronization therapy with defibrillator (CRT-D) (n=40) applied to our hospital's outpatient pacemaker clinic for follow-up...
April 19, 2017: Anatolian Journal of Cardiology
https://www.readbyqxmd.com/read/28428073/isosteviol-prevents-the-prolongation-of-action-potential-in-hypertrophied-cardiomyoctyes-by-regulating-transient-outward-potassium-and-l-type-calcium-channels
#4
Zhuo Fan, Nanying Lv, Xiao Luo, Wen Tan
Cardiac hypertrophy is a thickening of the heart muscle that is associated with cardiovascular diseases such as hypertension and myocardial infarction. It occurs initially as an adaptive process against increased workloads and often leads to sudden arrhythmic deaths. Studies suggest that the lethal arrhythmia is attributed to hypertrophy-induced destabilization of cardiac electrical activity, especially the prolongation of the action potential. The reduced activity of Ito is demonstrated to be responsible for the ionic mechanism of prolonged action potential duration and arrhythmogeneity...
April 17, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28424631/mechanisms-underlying-the-emergence-of-post-acidosis-arrhythmia-at-the-tissue-level-a-theoretical-study
#5
Jieyun Bai, Renli Yin, Kuanquan Wang, Henggui Zhang
Acidosis has complex electrophysiological effects, which are associated with a high recurrence of ventricular arrhythmias. Through multi-scale cardiac computer modeling, this study investigated the mechanisms underlying the emergence of post-acidosis arrhythmia at the tissue level. In simulations, ten Tusscher-Panfilov ventricular model was modified to incorporate various data on acidosis-induced alterations of cellular electrophysiology and intercellular electrical coupling. The single cell models were incorporated into multicellular one-dimensional (1D) fiber and 2D sheet tissue models...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28422349/effects-of-extrinsic-cardiac-nerve-stimulation-on-atrial-fibrillation-inducibility-the-regulatory-role-of-the-spinal-cord
#6
Zixuan Dai, Congxin Huang, Qingyan Zhao, Shujuan Zhang, Hongyi Zhao, Youjing Zhang, Yongsheng Qian, Yanhong Tang
OBJECTIVE: To investigate the effect of the mutual regulation of the extrinsic cardiac nerves on atrial electrophysiology and atrial fibrillation (AF) vulnerability. METHODS AND RESULTS: Fourteen dogs were randomly divided into 2 groups: spinal cord stimulation (SCS) group (n = 7) and spinal cord block (SCB) group (n = 7). SCS was performed with 90% of the threshold voltage stimulating the T1 -T2 spinal level, while SCB was performed by injecting 2% lidocaine into the epidural space at the T2-3 level...
April 19, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28421394/waveform-integrity-in-atrial-fibrillation-the-forgotten-issue-of-cardiac-electrophysiology
#7
Miguel Martínez-Iniesta, Juan Ródenas, Raúl Alcaraz, José J Rieta
Atrial fibrillation (AF) is the most common arrhythmia in clinical practice with an increasing prevalence of about 15% in the elderly. Despite other alternatives, catheter ablation is currently considered as the first-line therapy for the treatment of AF. This strategy relies on cardiac electrophysiology systems, which use intracardiac electrograms (EGM) as the basis to determine the cardiac structures contributing to sustain the arrhythmia. However, the noise-free acquisition of these recordings is impossible and they are often contaminated by different perturbations...
April 18, 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/28418441/an-integrated-anti-arrhythmic-target-network-of-a-chinese-medicine-compound-wenxin-keli-revealed-by-combined-machine-learning-and-molecular-pathway-analysis
#8
Taiyi Wang, Ming Lu, Qunqun Du, Xi Yao, Peng Zhang, Xiaonan Chen, Weiwei Xie, Zheng Li, Yuling Ma, Yan Zhu
Wenxin Keli (WK), a Chinese patent medicine, is known to be effective against cardiac arrhythmias and heart failure. Although a number of electrophysiological findings regarding its therapeutic effect have been reported, the active components and system-level characterizations of the component-target interactions of WK have yet to be elucidated. In the current study, we present the first report of a new protective effect of WK on suppressing anti-arrhythmic-agent-induced arrhythmias. In a model of isolated guinea pig hearts, rapid perfusion of quinidine altered the heart rate and prolonged the Q-T interval...
April 18, 2017: Molecular BioSystems
https://www.readbyqxmd.com/read/28416514/optical-mapping-approaches-on-muscleblind-like-compound-knockout-mice-for-understanding-mechanistic-insights-into-ventricular-arrhythmias-in-myotonic-dystrophy
#9
Chung-Chuan Chou, Po-Cheng Chang, Yi-Chia Wei, Kuang-Yung Lee
BACKGROUND: Cardiac arrhythmias are common causes of death in patients with myotonic dystrophy (dystrophia myotonica [DM]). Evidence shows that atrial tachyarrhythmia is an independent risk factor for sudden death; however, the relationship is unclear. METHODS AND RESULTS: Control wild-type (Mbnl1(+/+); Mbnl2(+/+) ) and DM mutant (Mbnl1(-/-); Mbnl2(+/-) ) mice were generated by crossing double heterozygous knockout (Mbnl1(+/-); Mbnl2(+/-) ) mice. In vivo electrophysiological study and optical mapping technique were performed to investigate mechanisms of ventricular tachyarrhythmias...
April 17, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28408652/premature-ventricular-contraction-coupling-interval-variability-destabilizes-cardiac-neuronal-and-electrophysiological-control-insights-from-simultaneous-cardioneural-mapping
#10
David Hamon, Pradeep S Rajendran, Ray W Chui, Olujimi A Ajijola, Tadanobu Irie, Ramin Talebi, Siamak Salavatian, Marmar Vaseghi, Jason S Bradfield, J Andrew Armour, Jeffrey L Ardell, Kalyanam Shivkumar
BACKGROUND: Variability in premature ventricular contraction (PVC) coupling interval (CI) increases the risk of cardiomyopathy and sudden death. The autonomic nervous system regulates cardiac electrical and mechanical indices, and its dysregulation plays an important role in cardiac disease pathogenesis. The impact of PVCs on the intrinsic cardiac nervous system, a neural network on the heart, remains unknown. The objective was to determine the effect of PVCs and CI on intrinsic cardiac nervous system function in generating cardiac neuronal and electric instability using a novel cardioneural mapping approach...
April 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28408649/external-arrhythmia-ablation-using-photon-beams-ablation-of-the-atrioventricular-junction-in-an-intact-animal-model
#11
H Immo Lehmann, Amanda J Deisher, Mitsuru Takami, Jon J Kruse, Limin Song, Sarah E Anderson, Jack T Cusma, Kay D Parker, Susan B Johnson, Samuel J Asirvatham, Robert C Miller, Michael G Herman, Douglas L Packer
BACKGROUND: This study sought to investigate external photon beam radiation for catheter-free ablation of the atrioventricular junction in intact pigs. METHODS AND RESULTS: Ten pigs were randomized to either sham irradiation or irradiation of the atrioventricular junction (55, 50, 40, and 25 Gy). Animals underwent baseline electrophysiological evaluation, cardiac gated multi-row computed tomographic imaging for beam delivery planning, and intensity-modulated radiation therapy...
April 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28408648/azithromycin-causes-a-novel-proarrhythmic-syndrome
#12
Zhenjiang Yang, Joseph K Prinsen, Kevin R Bersell, Wangzhen Shen, Liudmila Yermalitskaya, Tatiana Sidorova, Paula B Luis, Lynn Hall, Wei Zhang, Liping Du, Ginger Milne, Patrick Tucker, Alfred L George, Courtney M Campbell, Robert A Pickett, Christian M Shaffer, Nagesh Chopra, Tao Yang, Bjorn C Knollmann, Dan M Roden, Katherine T Murray
BACKGROUND: The widely used macrolide antibiotic azithromycin increases risk of cardiovascular and sudden cardiac death, although the underlying mechanisms are unclear. Case reports, including the one we document here, demonstrate that azithromycin can cause rapid, polymorphic ventricular tachycardia in the absence of QT prolongation, indicating a novel proarrhythmic syndrome. We investigated the electrophysiological effects of azithromycin in vivo and in vitro using mice, cardiomyocytes, and human ion channels heterologously expressed in human embryonic kidney (HEK 293) and Chinese hamster ovary (CHO) cells...
April 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28407402/cirrhotic-cardiomyopathy-implications-for-liver-transplantation
#13
REVIEW
Hongqun Liu, Saumya Jayakumar, Mouhieddin Traboulsi, Samuel S Lee
The majority of the patients on a waiting list for liver transplantation have end-stage liver disease. Due to the marked peripheral vasodilatation of end stage cirrhosis that masks a latent myocardial dysfunction, cardiac abnormalities in the resting state are usually subclinical and escape the attention of physicians. However, when challenged, the systolic and diastolic contractile responses are attenuated. In addition to these contractile abnormalities, morphological changes such as enlargement or hypertrophy of cardiac chambers and electrophysiological repolarization changes including a prolonged QT interval can be observed...
April 13, 2017: Liver Transplantation
https://www.readbyqxmd.com/read/28405065/practical-and-ethical-considerations-in-the-management-of-pacemaker-and-implantable-cardiac-defibrillator-devices-in-terminally-ill-patients
#14
REVIEW
Mina M Benjamin, Christine A Sorkness
More than 4.5 million people worldwide live with an implanted pacemaker, including >3 million in the USA alone. Also, >0.8 million people in the USA have an implantable cardioverter defibrillator (ICD). Knowing the principles of managing these devices towards the end of life is important, as the interruption of their function may have serious consequences. This article provides health care providers who are not specialized in cardiac electrophysiology with an introduction to the general principles of management of pacemakers or ICD devices towards the end of life, with a suggested algorithm for approaching this process...
April 2017: Proceedings of the Baylor University Medical Center
https://www.readbyqxmd.com/read/28403018/prophylactic-atropine-administration-attenuates-the-negative-haemodynamic-effects-of-induction-of-anaesthesia-with-propofol-and-high-dose-remifentanil-a-randomised-controlled-trial
#15
Marieke Poterman, Thomas W L Scheeren, Marieke I van der Velde, Pieter L Buisman, Silvie Allaert, Michel M R F Struys, Alain F Kalmar
BACKGROUND: Induction of anaesthesia with propofol and remifentanil often induces unwanted bradycardia and hypotension, raising concerns regarding tissue oxygenation. The electrophysiological cardiac effects of remifentanil can be reversed by atropine. OBJECTIVE: To investigate if prophylactic administration of atropine can attenuate the negative haemodynamic effects of propofol and a high dose of remifentanil during induction of anaesthesia. DESIGN: A double-blind, randomised controlled trial...
April 11, 2017: European Journal of Anaesthesiology
https://www.readbyqxmd.com/read/28402037/atrial-electrophysiological-and-molecular-remodelling-induced-by-obstructive-sleep-apnoea
#16
Devika Channaveerappa, Jacob C Lux, Kelly L Wormwood, Timothy A Heintz, Meredith McLerie, Jacqueline A Treat, Hannah King, Donia Alnasser, Robert J Goodrow, Glenn Ballard, Robert Decker, Costel C Darie, Brian K Panama
Obstructive sleep apnoea (OSA) affects 9-24% of the adult population. OSA is associated with atrial disease, including atrial enlargement, fibrosis and arrhythmias. Despite the link between OSA and cardiac disease, the molecular changes in the heart which occur with OSA remain elusive. To study OSA-induced cardiac changes, we utilized a recently developed rat model which closely recapitulates the characteristics of OSA. Male Sprague Dawley rats, aged 50-70 days, received surgically implanted tracheal balloons which were inflated to cause transient airway obstructions...
April 12, 2017: Journal of Cellular and Molecular Medicine
https://www.readbyqxmd.com/read/28398813/neural-correlates-of-consciousness-at-near-electrocerebral-silence-in-an-asphyxial-cardiac-arrest-model
#17
Donald E Lee, Lauren G Lee, Danny Siu, Afsheen K Bazrafkan, Maryam H Farahabadi, Tin J Dinh, Josue Orellana, Wei Xiong, Beth A Lopour, Yama Akbari
Recent electrophysiological studies have suggested surges in electrical correlates of consciousness (i.e., elevated gamma power and connectivity) after cardiac arrest (CA). This study examines electrocorticogram (ECoG) activity and coherence of the dying brain during asphyxial CA. Male Wistar rats (n = 16) were induced with isoflurane anesthesia, which was washed out before asphyxial CA. Mean phase coherence and ECoG power were compared during different stages of the asphyxial period to assess potential neural correlates of consciousness...
April 2017: Brain Connectivity
https://www.readbyqxmd.com/read/28397099/maturation-of-human-pluripotent-stem-cell-derived-cardiomyocytes-is-improved-in-cardiovascular-construct
#18
Hanna Vuorenpää, Kirsi Penttinen, Tuula Heinonen, Mari Pekkanen-Mattila, Jertta-Riina Sarkanen, Timo Ylikomi, Katriina Aalto-Setälä
In order to translate preclinical data into the clinical studies, relevant in vitro models with structure and key functional properties similar to native human tissue should be used. In vitro cardiac models with vascular structures mimic the highly vascularized myocardium and provide interactions between endothelial cells, stromal cells and cardiomyocytes. Currently, human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have been shown to present immature morphology and fetal-like electrophysiological properties that may limit their use as physiological test platform...
April 10, 2017: Cytotechnology
https://www.readbyqxmd.com/read/28396856/bidomain-predictions-of-virtual-electrode-induced-make-and-break-excitations-around-blood-vessels
#19
Adam J Connolly, Edward Vigmond, Martin J Bishop
INTRODUCTION AND BACKGROUND: Virtual electrodes formed by field stimulation during defibrillation of cardiac tissue play an important role in eliciting activations. It has been suggested that the coronary vasculature is an important source of virtual electrodes, especially during low-energy defibrillation. This work aims to further the understanding of how virtual electrodes from the coronary vasculature influence defibrillation outcomes. METHODS: Using the bidomain model, we investigated how field stimulation elicited activations from virtual electrodes around idealized intramural blood vessels...
2017: Frontiers in Bioengineering and Biotechnology
https://www.readbyqxmd.com/read/28396172/role-of-suppression-of-the-inward-rectifier-current-ik1-on-terminal-action-potential-repolarization-in-the-failing-heart
#20
Michael G Klein, Matie Shou, Jayna Stohlman, Soroosh Sohljoo, Myles Haigney, Richard R Tidwell, Robert E Goldstein, Thomas P Flagg, Mark C Haigney
BACKGROUND: The failing heart exhibits an increased arrhythmia susceptibility that is often attributed to action potential (AP) prolongation due to significant ion channel remodeling. IK1 has been reported to be reduced, but its contribution to shaping the AP waveform and cell excitability in the failing heart remains unclear. OBJECTIVE: To define the effect of IK1 suppression on the cardiac AP and excitability in the normal and failing heart. METHODS: We used electrophysiological and pharmacological approaches to investigate IK1 function in a swine tachy-pacing model of heart failure...
April 7, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
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