The extent of reversibility of myocardial ischemia in dogs

Abstract

1. 1. Electrocardiographic, biochemical, and pathologic indications of temporary myocardial ischemia vary in the rate of appearance and reversibility. 2. 2. Electrocardiographic changes were consistently observed immediately following occlusion of the coronary artery, and these changes regressed toward the base-line record if coronary flow was reinstituted within 40 minutes. 3. 3. A significant rise in glutamic oxaloacetic transaminase was observed in the coronary sinus blood after 20 minutes of occlusion. An elevation of the enzyme concentration in the serum, even for a period of 40 minutes, does not necessarily indicate irreversible cellular damage. 4. 4. Tissue injury which was readily reversible occurred after 40 minutes of coronary occlusion. Sixty minutes of sustained tissue anoxia appears to be the critical period beyond which irreversible damage occurs.