IMPLICATIONS OF ION-CHANNEL DIVERSITY TO VENTRICULAR REPOLARIZATION AND ARRHYTHMOGENESIS - INSIGHTS FROM HIGH-RESOLUTION OPTICAL MAPPING

Citation
Kr. Laurita et Ds. Rosenbaum, IMPLICATIONS OF ION-CHANNEL DIVERSITY TO VENTRICULAR REPOLARIZATION AND ARRHYTHMOGENESIS - INSIGHTS FROM HIGH-RESOLUTION OPTICAL MAPPING, Canadian journal of cardiology, 13(11), 1997, pp. 1069-1076
Citations number
42
ISSN journal
0828282X
Volume
13
Issue
11
Year of publication
1997
Pages
1069 - 1076
Database
ISI
SICI code
0828-282X(1997)13:11<1069:IOIDTV>2.0.ZU;2-0
Abstract
Recent evidence from experiments in isolated cells suggests that subst antial ion channel diversity exists throughout the heart. However, due to limitations of conventional electrophysiological recording techniq ues, the influence of ion channel diversity on ventricular repolarizat ion and arrhythmia vulnerability at the level of the intact heart are poorly understood. High resolution optical mapping with voltage-sensit ive dye was used to measure significant heterogeneity in the kinetics of cellular repolarization between cells across the epicardial surface (1x1 cm) of the intact guinea-pig heart. Such diversity of repolariza tion kinetics modulates dispersion of repolarization in a biphasic fas hion as premature coupling interval is shortened. Moreover, evidence i s provided that modulation of repolarization by a premature stimulus i n a coupling interval-dependent manner also modulates arrhythmia vulne rability in parallel, ie, 'modulated dispersion' hypothesis. Therefore , due to diversity of repolarization kinetics between epicardial cells , a premature stimulus serves not only as a 'trigger' of arrhythmias, but also importantly modulates spatial dispersion of repolarization an d the arrhythmogenic substrate for reentry.