The effect of coronary artery bypass on collateral circulation.

The effect of coronary bypass upon collateral circulation (CC) was studied in 69 bypassed coronary arteries in which CC was seen on either the preoperative or postoperative angiogram or both. CC proved to be a highly reliable indicator of bypass effectiveness. Persistence or new development of CC on postoperative angiograms invariably indicated complete bypass obstruction or inadequate revascularization. Disappearance of preexisting CC on postoperative angiograms almost always indicated bypass patency. Occlusion of a bypass does not appear to jeopardize preexisting CC or prevent new CC from developing in most cases.