Effects of immature recruitable collaterals on myocardial blood flow and infarct size after acute coronary occlusion.

This study assessed the ability of immature recruitable coronary collateral vessels to alter regional myocardial blood flow and to protect jeopardized myocardium from infarction after acute coronary occlusion. An inflatable balloon occluder was placed around the left circumflex coronary artery of 7 dogs (group A), while nine dogs (group B) underwent placement of an Ameroid constrictor around the circumflex artery proximal to a balloon occluder. Group A dogs were studied 2 to 3 days after surgery; those in group B were studied 12 days after surgery, when partial collateralization had occurred. The circumflex artery was acutely occluded in both groups for 4 hours. Myocardial blood flow was measured with radioactive microspheres before, immediately after, and 4 hours after coronary occlusion. Infarct size, expressed as percent of left ventricular area at risk, was determined by triphenyl tetrazolium chloride staining after infusion of colored dyes to delineate perfusion beds. Flows in the ischemic circumflex bed 90 seconds after coronary occlusion decreased in both groups for both endocardial (0.04 +/- 0.02 ml/min/gm vs 0.09 +/- 0.04 ml/min/gm) and epicardial (0.19 +/- 0.07 ml/min/gm vs 0.26 +/- 0.08 ml/min/gm) layers. Four hours after coronary occlusion, endocardial flow did not rise significantly in group A (0.11 +/- 0.05 ml/min/gm), but increased significantly in group B to 0.52 +/- 0.13 ml/min/gm (p < 0.05). Epicardial flow at 4 hours was also significantly greater in group B (1.03 +/- 0.15 ml/min/gm) than in group A (0.55 +/- 0.13 ml/min/gm, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)