Comparison of the effect of temporary or permanent myocardial ischemia on cardiac function and pathology

Abstract

Summary To determine the exact safe period of temporary myocardial ischemia with preservation of the ventricular function and the myocardial histology, studies were carried out in 98 dogs which were divided into two groups. In chronic experiments, an area of localized myocardial ischemia was produced by temporarily occluding the anterior descending branch of the left coronary artery at various intervals. In this group, at least 40 minutes of ischemia was required to produce histologic changes of myocardial infarction comparable to those of a permanently occluded artery. In acute experiments, marked depression of the right and left ventricular function curves ensued, if the period of ischemia exceeded 15 minutes. It was concluded that temporary periods of localized myocardial ischemia, which result in left ventricular failure, are not necessarily associated with permanent myocardial damage. On the basis of these experiments the situation seen in patients who die of myocardial infarction, with or without complete occlusion of their coronary arteries, are explained. The authors would like to express their gratitude for the assistance of Mary E. Smith and Patricia Pollard.