Measurement of Infarct Size: Effect of Reperfusion with Arterial Blood

Abstract

The principles of experiment design for studies to assess the effect of therapy on acute myocardial ischemic injury are described, including ways in which such studies should be controlled for those factors which contribute to variation in infarct size. In the open-chest anesthetized dog, 90% of variation in infarct size is due to differences in the: 1) size of the vascular area at risk of infarction and, 2) volume of collateral arterial flow to this region. Although damaged by ischemia, myocytes do not die if the myocardium is reperfused with arterial blood less than 15 minutes after the onset. However, virtually all severely and moderately ischemic myocytes will be dead after six hours of ischemia have passed. The damaged myocytes die first in the subendocardium and then in a wavefront which extends out to and may include the subepicardial myocardium. In most hearts, some myocytes still are salvageable by reperfusion after being subjected to episodes of ischemia of as long as three hours.