Internal mammary artery: a "live" conduit for coronary bypass.

An angiographic study of the internal mammary artery graft 8 years postoperatively illustrates the physiological nature of this conduit. Changes in the caliber of the internal mammary artery graft are seen to occur in response to changes in the size of the coronary vascular bed, a phenomenon of autoregulation. This physiological adaptability differentiates the internal mammary artery graft from the saphenous vein graft and may be one of the reasons for excellent long-term performance of this conduit.