The effect of coronary collateral circulation on experimental aorto-coronary bypass

The relationship between collateral coronary flow and aorto-coronary bypass graft hemodynamics was investigated in two groups of dogs. In animals without significant collateral channels, occlusion of the left anterior descending coronary artery did not alter flow or peripheral coronary pressure in a bypass graft to the acutely ligated circumflex coronary artery. Six weeks after circumflex constriction, abundant collateral vessels were demonstrated in the second group and were associated with an elevation of peripheral circumflex pressure and a reduction of graft flow. Occlusion of the left anterior descending in these animals significantly increased graft flow and reduced peripheral circumflex pressure. Conversely, after occlusion of the graft, left anterior descending peripheral pressure decreased and flow increased. These data document an initial decrease in flow through an aorto-coronary graft in the presence of extensive coronary collaterals, but demonstrate a reduction in collateral flow after graft insertion.