Multiple Dynamical Mechanisms of Phase-2 Early Afterdepolarizations in a Human Ventricular Myocyte Model: Involvement of Spontaneous SR Ca2+Release

In this study, dynamical mechanisms of EAD formation in human ventricular myocytes (HVMs) were investigated using the mathematical model developed by ten Tusscher and Panfilov (Am J Physiol Heart Circ Physiol 291, 2006). We explored how the rapid (IKr) and slow (IKs) components of delayed-rectifier K+ channel currents, L-type Ca2+ channel current (ICaL), Na+/Ca2+ exchanger current (INCX), and intracellular Ca2+ handling via the sarcoplasmic reticulum (SR) contribute to initiation, termination and modulation of phase-2 EADs during pacing in relation to bifurcation phenomena in non-paced model cells. Parameter-dependent dynamical behaviors of the non-paced model cell were determined by calculating stabilities of equilibrium points (EPs) and limit cycles, and bifurcation points to construct bifurcation diagrams. Action potentials (APs) and EADs during pacing were reproduced by numerical simulations for constructing phase diagrams of the paced model cell dynamics. Results are summarized as follows: (1) A modified version of the ten Tusscher-Panfilov model with accelerated ICaL inactivation could reproduce bradycardia-related EADs in LQTS type 2 and β-adrenergic stimulation-induced EADs in LQTS type 1. (2) Two types of EADs with different initiation mechanisms, ICaL reactivation–dependent and spontaneous SR Ca2+ release–mediated EADs, were detected. (3) Termination of EADs (AP repolarization) during pacing depended on the slow activation of IKs. (4) Spontaneous SR...
Source: Frontiers in Physiology - Category: Physiology Source Type: research

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lini C, Shimamoto K, Tadros R, Cadrin-Tourigny J, Duff HJ, Simpson CS, Roston TM, Wijeyeratne YD, El Hajjaji I, Yousif MD, Gula LJ, Leong-Sit P, Chavali N, Landstrom AP, Marcus GM, Dittmann S, Wilde AAM, Behr ER, Tfelt-Hansen J, Scheinman MM, Perez MV, Kaski JP, Gow RM, Drago F, Aziz PF, Abrams DJ, Gollob MH, Skinner JR, Shimizu W, Kaufman ES, Roden DM, Zareba W, Schwartz PJ, Schulze-Bahr E, Etheridge SP, Priori SG, Ackerman MJ Abstract Background: Insight into type 5 long QT syndrome (LQT5) has been limited to case reports and small family series. Improved understanding of the clinical phenotype and genetic featu...
Source: Circulation - Category: Cardiology Authors: Tags: Circulation Source Type: research
We examined frequency, clinical characteristics and AF‐related management and outcomes amongst this patient population.MethodsWe retrospectively studied consecutive probands with inherited cardiomyopathy (n=962) and inherited arrhythmia syndromes (n=195) evaluated between 2002 ‐2018.ResultsAF was observed in 5 ‐31% of patients, with the highest frequency in HCM. Age of AF onset was 45.8 ± 21.9 years in the inherited arrhythmia syndromes compared to 53.3 ± 15.3 years in the inherited cardiomyopathies, with 4 CPVT patients developing AF at median age of 20 years. Overall, 11% of patients with AF had a t r...
Source: Journal of Cardiovascular Electrophysiology - Category: Cardiology Authors: Tags: ORIGINAL ARTICLE Source Type: research
ConclusionBoth mutations, KV7.1 A150T and L374H, led to loss of channel function. The degree of loss ‐of‐function may mirror the disease phenotype observed in the patients.This article is protected by copyright. All rights reserved
Source: Pacing and Clinical Electrophysiology : PACE - Category: Cardiology Authors: Tags: ELECTROPHYSIOLOGY Source Type: research
This report highlights a case of QT prolongation with torsades de pointes in a patient with baseline congenital long QT syndrome, believed to be precipitated by metabolic changes associated with the "ketogenic diet." PMID: 32063779 [PubMed]
Source: Baylor University Medical Center Proceedings - Category: Universities & Medical Training Authors: Tags: Proc (Bayl Univ Med Cent) Source Type: research
Authors: Trenkwalder T, Schunkert H, Reinhard W Abstract Molecular genetic analysis is an important component in the diagnostics of some cardiovascular diseases; however, genetic testing should not be used as a screening technique as the diagnostic value strongly depends on anamnestic and clinical factors, such as a positive family history and the disease phenotype. In cardiovascular diseases with high mutation detection rates, e.g. hypertrophic cardiomyopathy and primary arrhythmia syndromes (long QT syndrome, catecholaminergic polymorphic ventricular tachycardia) genetic testing should be included in th...
Source: Herz - Category: Cardiology Tags: Herz Source Type: research
Sympathetically triggered inherited arrhythmia syndromes, including the long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT), can cause sudden cardiac death in young individuals with structurally normal hearts. With cardiac events typically triggered by physical or emotional stress, not surprisingly, two of the most common treatments are neuromodulators, including mainstay beta blocker pharmacotherapy, and surgical sympathetic cardiac denervation. This review updates the clinician on the relevant anatomy and physiology of the cardiac autonomic nervous system, outlines neurocardiac arrhyt...
Source: Heart, Lung and Circulation - Category: Cardiology Authors: Source Type: research
Inherited heart diseases include numerous conditions, from the more prevalent hypertrophic cardiomyopathy (HCM) and familial hypercholesterolaemia (FH), to the comparatively less common inherited arrhythmia syndromes, such as long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT) and Brugada syndrome (BrS). Genetic testing has evolved rapidly over the last decade and is now considered a mainstream component of clinical management of inherited heart diseases. Cardiac manifestations can also be part of wider syndromes, and genetic testing can play a critical role in clarifying the underlying ae...
Source: Heart, Lung and Circulation - Category: Cardiology Authors: Tags: Review Source Type: research
We report a case of QTc prolongation associated with mild concussion in a pediatric patient. An 11-year-old male presented to the emergency department after sustaining a head injury during football practice. He complained of headache and blurry vision. Physical examination was within normal apart from an irregular heart rhythm. Electrocardiogram (ECG) showed normal sinus rhythm with QTc (Bazett formula) 460  ms. The patient was diagnosed with concussion and referred for cardiology follow-up of the QTc. ECG the next day showed QTc 462 ms (heart rate 105 bpm) supine and 494 ms after suddenly standing up (...
Source: Pediatric Cardiology - Category: Cardiology Source Type: research
Conclusion: Video-assisted CSD should be considered as a treatment option for patients with potentially dangerous arrhythmias that do not respond to conventional treatment, especially in recurrent ventricular tachycardia. PMID: 31588139 [PubMed - in process]
Source: Archivos de Cardiologia de Mexico - Category: Cardiology Authors: Tags: Arch Cardiol Mex Source Type: research
This article provides an updated review of the genetic basis, diagnosis and clinical management of LQTS.This article is protected by copyright. All rights reserved.
Source: Journal of Cardiovascular Electrophysiology - Category: Cardiology Authors: Tags: FELLOWS CORE CURRICULUM Source Type: research
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