The behavior of collateral circulation after coronary artery bypass surgery.

The changes in coronary collateral circulation after bypass surgery were analyzed in 50 patients with coronary disease. The demonstration of collateral circulation was found to be dependent upon the severity of the coronary heart disease and the patency of the bypass. When the graft was patent, it was usually not possible to visualize the collateral circulation demonstrated preoperatively. When the bypass was occluded, the same collateral circulation as before surgery was frequently found.