Differential effects of synchronized coronary sinus retroperfusion on regional myocardial function during brief occlusion of the left anterior descending and circumflex coronary arteries

Abstract

To test the hypothesis that coronary sinus retroperfusion would preserve regional myocardial function during either left anterior descending or circumflex occlusion, sonomicrometer crystals were implanted in the midmyocardium of five chronically instrumented dogs. Regional fractional shortening was measured during 5 min of coronary occlusion with and without retroperfusion. Percent fractional shortening in the left anterior descending region fell from 18% at baseline to -4%(dyskinesis) after 3 min of left anterior descending occlusion. With coronary sinus retroperfusion, the percent fractional shortening declined from 16% at baseline to 0 (akinesis) during occlusion. A modest but significant improvement in percent fractional shortening in the ischemic region during left anterior descending occlusion occurred with retroperfusion (p < .05). By contrast, no amelioration of ischemic dysfunction occurred with retroperfusion during circumflex occlusion. Coaxial flow into the great cardiac vein during retroperfusion may provide preferential protection to ischemic myocardium supplied by the left anterior descending coronary artery. However, it is unlikely that the modest degree of improvement in regional function observed during acute left anterior descending occlusion would be mechanically important in the presence of significant ischemic dysfunction.

Intraaortic balloon counterpulsation with synchronized coronary venous retroperfusion: The united states experience

“…We found that with adequate coronary sinus retroperfusion, the dyskinesis occurring with left anterior descending occlusions could be improved to akinesis; however, the myocardium still failed to contract during profound ischemia [4]. Unfortunately, during circumflex ischemia in the same animal model, coronary sinus retroperfusion appeared to do little to support mechanical function [4].Verdouw and colleagues [5] suggested that for regional function to be maintained in the pig model with retroperfusion, very high coronary sinus pressures were necessary. These pressures did support reasonable function for a brief period of time; however, subsequently edema in the myocardium developed with further compromise in regional function [ 5 ] .…”

“…We attempted to determine whether coronary sinus retroperfusion could in fact support the circulation or at least partially support regional function during a failed PTCA in an animal model. We found that with adequate coronary sinus retroperfusion, the dyskinesis occurring with left anterior descending occlusions could be improved to akinesis; however, the myocardium still failed to contract during profound ischemia [4]. Unfortunately, during circumflex ischemia in the same animal model, coronary sinus retroperfusion appeared to do little to support mechanical function [4].…”

Aggressive Interventional Treatment of Acute Myocardial Infarction

“…Balloon deflation in systole permits drain age of the coronary sinus preventing damage to venules and capillaries that accompanies prolonged occlusion and high coronary sinus pressure. Experimental studies with occlusion of the left anterior descending coronary artery have shown improved myocardial metabolic and func tional performance as well as a reduction in infarct size in animals treated with coronary sinus retroperfusion (CSR) [9,62,63], While impressive results in myocardial salvage have been reported, only modest improvements in region al myocardial function with CSR have been observed in animal models and in patients undergoing angioplasty [62,64,65], Dyskinetic ischemic segments essentially become akinetic with CSR. It appears that while CSR sup plies sufficient collateral blood flow to prevent ischemic cell death, this form of support may not be sufficient to promote myocardial contraction or be mechanically im portant in the presence of significant ischemic dysfunc tion [64],…”