Transmural reentry triggered by epicardial stimulation during acute ischemia in canine ventricular muscle

Jiashin Wu, Douglas P. Zipes

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

Ischemia depresses tissue excitability more rapidly in the ventricular epicardium than in the endocardium. We hypothesized that this would provide the substrate for transmural reentry originating in the epicardium. We mapped transmural conduction in isolated and perfused wedges taken from canine left ventricles during global ischemia while pacing alternately between the epicardium and endocardium. Ischemia reduced conduction velocity more in the epicardium than in the endocardium. We observed that the epicardial-initiated activation penetrated the ventricular wall transmurally while failing to conduct laterally along the epicardium, then conducted laterally along the endocardium and midmyocardium, and reentered the epicardium in 9 of 16 wedges during epicardial stimulation after 600 ± 182 s of ischemia. Endocardial stimulation applied immediately before or after the epicardial stimulation initiated activation that spread quickly along the endocardium and then transmurally to the epicardium without reentry in six of the nine wedges. The transmural asymmetric conduction was not observed in four separate wedges after the endocardium was removed. Therefore, ischemia-induced transmural gradient of excitability provided the substrate for reentry during epicardial stimulation.

Original languageEnglish (US)
Pages (from-to)H2004-H2011
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume283
Issue number5 52-5
StatePublished - Nov 1 2002

Keywords

  • Conduction asymmetry
  • Optical mapping
  • Transmural gradient
  • Ventricular wedge

ASJC Scopus subject areas

  • Physiology

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