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 colla teral vessels to alter regional myocardial blood flow and to protect j eopardized myocardium from infarction after acute coronary occlusion. An inflatable balloon occluder was placed around the left circumflex c oronary artery of 7 dogs (group A), while nine dogs (group B) underwen t placement of an Ameroid constrictor around the circumflex artery pro ximal to a balloon occluder. Group A dogs were studied 2 to 3 days aft er surgery; those in group B were studied 12 days after surgery, when partial collateralization had occurred. The circumflex artery was acut ely occluded in both groups for 4 hours. Myocardial blood flow was mea sured with radioactive microspheres before, immediately after, and 4 h ours offer coronary occlusion. Infarct size, expressed as percent of l eft ventricular area at risk, was determined by triphenyl tetrazolium chloride staining after infusion of colored dyes to delineate perfusio n beds. Flows in the ischemic circumflex bed 90 seconds after coronary occlusion decreased in both groups for both endocardial (0.04 +/- 0.0 2 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 coronar y occlusion, endocardial flow did not rise significantly in group A (0 .11 +/- 0.05 ml/min/gm), but increased significantly in group B to 0.5 2 +/- 0.13 ml/min/gm (p < 0.05). Epicardial flow at 4 hours was also s ignificantly greater in group B (1.03 +/- 0.15 ml/min/gm) than in grou p A (0.55 +/- 0.13 ml/min/gm, a < 0.05). Infarct size was 44.6% +/- 8. 5% of the circumflex perfusion bed in group A, while in group B it was only 9.8% +/- 3.4% of the perfusion bed (p < 0.05). Thus, developing collaterals augment coronary blood flow after acute coronary occlusion , and these recruitable collaterals do significantly reduce infarct si ze.