Journal ArticleDOI
Cellular Basis for the Electrocardiographic J Wave
Gan-Xin Yan,Charles Antzelevitch +1 more
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TLDR
The results provide the first direct evidence in support of the hypothesis that heterogeneous distribution of a transient outward current-mediated spike-and-dome morphology of the action potential across the ventricular wall underlies the manifestation of the electrocardiographic J wave.Abstract:
Background The J wave is a deflection that appears in the ECG as a late delta wave following the QRS or as a small secondary R wave (R′). Also referred to as an Osborn wave, the J wave has been observed in the ECG of animals and humans for more than four decades, yet the mechanism underlying its manifestation is poorly understood. The present study investigates the cellular basis for the J wave using an isolated arterially perfused preparation consisting of a wedge of canine right or left ventricle. Methods and Results A 12-lead ECG was initially recorded in vivo. After isolation and arterial perfusion of the right or left ventricular wedge, transmembrane action potentials were simultaneously recorded from epicardial, M region, and endocardial transmural sites with three floating microelectrodes. A transmural ECG was recorded concurrently. A J wave was observed at the R-ST junction of the ECG in 17 of 20 adult dogs, usually in leads II, III, aVR, and aVF and the mid to lateral precordial leads. The J wave...read more
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Journal ArticleDOI
Molecular genetics of arrhythmias and cardiovascular conditions associated with arrhythmias.
TL;DR: This brief review summarizes the present understanding of the genetic basis for disease and the genetic factors that contribute to the manifestation and pathogenesis of arrhythmic disorders.
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Arrhythmia formation in subclinical (“silent”) long QT syndrome requires multiple insults: Quantitative mechanistic study using the KCNQ1 mutation Q357R as example
Thomas O'Hara,Yoram Rudy +1 more
TL;DR: Accurate mathematical models of the human action potential and β-adrenergic stimulation are utilized to quantitatively investigate arrhythmia-formation mechanisms peculiar to silent long QT syndrome, using mutation Q357R in KCNQ1 (α subunit of slow-delayed rectifier I(Ks)) as a paradigm.
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Effect of dronedarone on Na+, Ca2+ and HCN channels
TL;DR: Investigation of the impact of the new antiarrhythmic compound dronedarone on Na+, Ca2+ and hyperpolarization-activated cyclic nucleotide-gated ion channels found it inhibits HCN4 currents, which might contribute to the clinically observed reduction in heart rate seen in patients in sinus rhythm after dron Cedarone treatment.
Journal ArticleDOI
The M Cell
TL;DR: The discovery of cells in the midmyocardial layers of ventricular myocardium with unique repolarization properties has prompted investigators in the field to revisit some old concepts and advance new ones relative to their understanding of the electrophysiology, pharmacology, and pathophysiology of the ventricles of the heart and the electrocardiographic signals that they generate.
Journal ArticleDOI
Prominent J wave and ST segment elevation: serial electrocardiographic changes in accidental hypothermia.
TL;DR: This work aims to provide a clear picture of the immune system’s role in the development of atherosclerosis and the immune response to these conditions is studied.
References
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Right bundle branch block, persistent ST segment elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. A multicenter report.
Pedro Brugada,Josep Brugada +1 more
TL;DR: Common clinical and ECG features define a distinct syndrome in this group of patients with recurrent episodes of aborted sudden death unexplainable by currently known diseases, not explainable by electrolyte disturbances, ischemia or structural heart disease.
Journal ArticleDOI
Heterogeneity within the ventricular wall. Electrophysiology and pharmacology of epicardial, endocardial, and M cells.
Charles Antzelevitch,Serge Sicouri,Silvio H. Litovsky,Anton Lukas,S C Krishnan,J. M. Di Diego,G. A. Gintant,Da-Wei Liu +7 more
TL;DR: In spite of important advances in cardiology in recent years, pharmacological control of cardiac arrhythmias in the clinic remains an experiment conducted on a patient-by-patient basis using a trial and error approach tempered by good clinical judgment.
Journal ArticleDOI
Inward current channels activated by intracellular Ca in cultured cardiac cells.
TL;DR: Researchers report here studies on single channel currents recorded from heart muscle cells, in which they have found a channel, abundant in cardiac membrane, which does not seem to belong in any of the familiar categories.
Journal ArticleDOI
Characteristics of the Delayed Rectifier Current (IKr and IKs) in Canine Ventricular Epicardial, Midmyocardial, and Endocardial Myocytes A Weaker IKs Contributes to the Longer Action Potential of the M Cell
Da-Wei Liu,Charles Antzelevitch +1 more
TL;DR: The results suggest that the distinctive phase-3 repolarization features of M cells are due in part to a lesser contribution of IKs and that this distinction may also explain why M Cells are the main targets for agents that prolong APD in ventricular myocardium.
Journal ArticleDOI
Influences of anisotropic tissue structure on reentrant circuits in the epicardial border zone of subacute canine infarcts.
TL;DR: It is proposed that the parallel orientation of the muscle bundles in the epicardial border zone is an important cause of ventricular tachycardia because activation transverse to myocardial fibers is sufficiently slow to permit the occurrence of reentry.
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