Flow study of coronary-coronary bypass grafting.

Coronary-coronary bypass grafting was recently introduced for patients with either calcification of the ascending aorta or an inadequate length of graft. Flow in the coronary-coronary bypass graft and that in aortocoronary bypass to the same coronary bed was compared in eight mongrel dogs. Flow reserve of the proximal right coronary artery as a donor vessel to the coronary-coronary bypass graft was also measured. Both a coronary-coronary and aortocoronary bypass were constructed to the proximally ligated left anterior descending artery. The flow in each graft was measured with the other graft temporarily occluded. Flow reserve of the right coronary artery (mean internal diameter 1.5mm) proximal to the anastomosis was measured before and after opening of the coronary-coronary bypass. Mean(s.d.) flow as 50.0(12.3) ml/min in the coronary-coronary bypass graft and 54.9(14.8) ml/min in the aortocoronary bypass, which was not significantly different. Flow curve studies demonstrated early systolic flow reversal in the aortocoronary bypass, while the coronary-coronary bypass showed only forward flow. Mean(s.d.) flow in the proximal right coronary artery increased from 35.4(11.8) to 76.0(15.3) ml/min after opening the coronary-coronary bypass graft, which had a flow rate of 42.2(10.4) ml/min. It is concluded that the coronary-coronary bypass graft can provide nearly the same flow rate as aortocoronary bypass, and that the proximal right coronary artery has sufficient flow reserve for this technique.