In the pathological aspect of J wave syndrome, delayed depolarization is defined as the difference in local conduction velocity of the ventricular myocardium. If polymorphic ventricular tachycardia is induced without local conduction velocity heterogeneity, this contradicts the
delayed depolarization theory. In the present study, the transmural conduction time at was evaluated at several transmural locations in a canine early repolarization model. The transmural pseudoelectrocardiogram and endocardial/epicardial action potentials were recorded from coronaryperfused
canine left ventricular wedge preparations (n=18). The Ito agonist NS5806 (910 µM), Ca2+ channel blocker verapamil (2 µM) and acetylcholine (ACh) (2 µM) were used to pharmacologically mimic early repolarization syndrome genotypes. The transmural conduction
times were measured at five fixed epicardial unipolar electrodes before and after the perfusion of provocative agents. The transmural conduction time was defined as the time from endocardial stimulation to the maximal negative deflection (dV/dt) of the endocardial electrogram at the unipolar
electrode. Polymorphic ventricular tachycardia developed in 14/18 preparations. In the transmembrane action potentials, there was no definite delayed phase 0 upstroke in any induced polymorphic ventricular tachycardia preparations. In all preparations, the transmural conduction time increased
significantly after perfusing the Ito agonist NS5806, verapamil and Ach; however, the increase was only 2.6±0.4 msec, and dispersion of the transmural conduction time did not exhibit significant heterogeneity (7.16±0.93 vs. 7.76±1.21 msec; P=0.240). In the early repolarization
model, polymorphic ventricular tachycardia was induced without any regional conduction velocity heterogeneity. This finding suggests that local depolarization heterogeneity would not be a major contributor to the generation of ventricular arrhythmia in the early repolarization syndrome wedge
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Document Type: Research Article
Department of Cardiovascular Medicine, Heart Center of Chonnam National University Hospital, Chonnam National University Medical School, Chonnam National University, Donggu, Gwangju 61469, Republic of Korea
October 1, 2020
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Experimental and Therapeutic Medicine aims to ensure the expedient publication, in both print and electronic format, of studies relating to biology, gene therapy, infectious disease, microbiology, molecular cardiology and molecular surgery. The journal welcomes studies pertaining to all aspects of molecular medicine, and studies relating to in vitro or in vivo experimental model systems relevant to the mechanisms of disease are also included.
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