Regional Myocardial Blood Flow in Patients with Residual Anterior and Inferior Transmural Infarction

Abstract

Regional myocardial perfusion rates were estimated in ten patients with a residual transmural anterior wall infarction and ten patients with a residual transmural inferior infarction. The results in these two groups of patients were compared to the regional myocardial perfusion patterns obtained in 25 patients with normal coronary arteriograms who failed to demonstrate any electrocardiographic evidence of a myocardial infarction. Clearance rates of xenon-133 from multiple areas of the heart were monitored externally with a multiple-crystal scintillation camera following selective injection of the isotope into either coronary artery. Local myocardial blood flow rates were calculated by the Kety formula. In patients with normal coronary arteriograms, mean myocardial perfusion rates in the left ventricle (62 ml/l00g/min) exceeded flow rates in the right ventricle and atrium. There was slight inhomogeneity of local perfusion rates but no significant differences among major subregions (anterior descending, diagonal, or circumflex) within the left ventricle. In the group with an anterior transmural infarction, myocardial blood flow rates were significantly depressed (44 ml/l00g/min) and asynergy was present in the region of the left ventricle supplied by the anterior descending artery, which was >80% narrowed. Diminished capillary blood flow was found in the right ventricular region in the patients with an inferior transmural infarction and right coronary artery narrowing of >80%. There was no evidence of nutrient flow to the inferior surface of the left ventricle after right coronary 133 Xe injection. The data indicate that myocardial perfusion was reduced in regions of the heart which correspond to the electrocardiographic and angiographic location of residual transmural infarction. The perfusion rates observed in areas showing electrocardiographic evidence of transmural infarction and regional ventricular asynergy, although subnormal, were surprisingly high and suggested the presence of residual viable myocardial cells.