Effects of Coronary Artery Reperfusion on Recovery of Regional Myocardial Function In Conscious Dogs

Abstract

The effects of coronary artery occlusion and reperfusion at 1 h (1-h group), 2 h (2-h group) and 3-h (3-h group) were compared with a permanently occluded group (P group) on measurements of overall left ventricular (LV) and regional endocardial function over a 4-wk period. The experiments were conducted in conscious dogs 1–3 wk after recovery from instrumentation with solid-state LV pressure gauges, aortic and left atrial catheters, hydraulic occluders and Doppler flow transducers on the left circumflex coronary artery, and multiple pairs of ultrasonic transducers implanted in the endocardial third of the LV free wall to measure endocardial segment shortening. During coronary artery occlusion, similar haemodynamic effects were observed in each of the four groups. At 1 h after coronary artery occlusion, systolic shortening was depressed by over 100%. In the P group, systolic shortening remained depressed by 86 ± 6·8% 4 wk later. Considerable return of function occurred in the 1-h group—i.e., shortening remained depressed by only 30 ± 7·4%. Systolic shortening remained depressed by 58 ± 9·1% in the 2-h group and by 78 ± 5·6% in the 3-h group. Thus, in the conscious dog, coronary artery reperfusion at 1h after coronary artery occlusion results in substantial return of endocardial function in the most severely ischaemic myocardium. However, after 3 h of coronary artery occlusion, little salvage of regional endocardial myocardial function can be induced by acute reperfusion in this model.