Cellular electrophysiological marker of irreversible ischemic myocardial injury

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Abstract
Glass microelectrode studies on posterior papillary muscle (PPM) slice preparations from 20 pentobarbital-anesthetized dogs (15 subjected to prior circumflex coronary artery ligation, 5 to sham ligation) have resulted in the definition of an electrophysiological marker of irreversible ischemic injury: areas composed of cells unable to generate a significant resting potential (< -25 mV), designated electrically inactive areas. Electrically inactive areas were essentially confined to PPM from dogs with circumflex coronary ligation; the incidence and distribution of the areas was related to duration of ischemia. Correlative phase- and light-microscopic studies demonstrated close correspondence between such areas and morphological evidence of irreversible ischemic injury. Analysis of frequency and distribution of electrically inactive areas permitted quantitative assessment of the extent and spatial distribution of irreversible injury. This method was used to quantitate injury in PPM from dogs subjected to ligation for varying time periods. The potential utility of this method for evaluation of interventions designed to protect against ischemic injury and to assess electrical properties of surviving cells is considered.