Comparison of Human Ventricular Activation with a Canine Model in Chronic Myocardial Infarction

Ventricular activation was studied in 20 patients with ischemic heart disease at the time of surgery for myocardial revascularization. Because most of the activation studies in man were limited to recording of epicardial potentials, a canine model of chronic infarction was also studied. Pre- and postinfarction data were recorded in dogs and correlated with the anatomy of the lesions. Epicardial Q waves, when associated with delayed epicardial activation, were diagnostic of underlying infarctions in areas of the heart that did not normally exhibit Q waves. In areas normally containing Q waves, underlying infarction was associated with Q waves greater in duration than the normal range determined for those areas of the epicardium. The experimental model of chronic infarction showed epicardial delay to be due to slowed intramyocardial activation rather than to delay in Purkinje conduction. Correlations between electrical and anatomic data in two patients suggested that, within limits, the detailed relationships between infarction and activation established with the canine model could be applied to human infarction to understand the genesis of the epicardial potentials and the ECG. The technique was also felt to have a practical clinical application in selection of areas of myocardium for vascular implants or infarctectomy.