In vivo functional flowmetric behavior of the radial artery graft: is the composite Y-graft configuration advantageous over conventional aorta-coronary bypass?

Abstract

Intraoperative flowmetric results of different configurations (Y-graft or aorta-coronary) of radial artery grafts have been poorly investigated. We report the results of an observational study designed to analyze transit-time flow measurements at baseline and during 1:1 intra-aortic balloon pumping in 114 consecutive patients receiving the radial artery as a aorta-coronary bypass (group A, 72 patients) or as a Y-graft with the left internal thoracic artery (group B, 42 patients). Graft flow reserve, recruited by 1:1 intra-aortic balloon pumping) greater than 1 indicated recruitment of surplus graft flow. Results were stratified by grafted territory and surgical technique. Hospital outcome was comparable. Baseline transit-time flow results were similar between the 2 groups in terms of maximum diastolic flow, minimum systolic flow, mean flow, and pulsatility index. Graft flow reserve was not recruited by intra-aortic balloon pumping in 3 (2.7%) malfunctioning single aorta-oronary radial artery bypass grafts (P = .005 versus successful radial artery bypass grafts). Graft flow reserve was recruited (>1) by intra-aortic balloon pumping in the remaining 111 patent radial artery bypass grafts. Y-grafts showed higher maximum diastolic flow P < .0001), mean flow (P < .0001), graft flow reserve (P < .0001), percentage improvement of maximum diastolic flow (P < .0001), and of mean flow (P < .0001) compared with aorta-coronary radial artery bypass grafts. These results were confirmed for the right coronary (P < or = .004) and the circumflex territory (P < or = .001), for off-pump (P < or = .008) or cardiopulmonary bypass (P < .0001) and for patients undergoing isolated bypass grafting (P < .0001). Intraoperative flows of radial artery bypass grafts showed comparable baseline results in single aorta-coronary conduits and Y-grafts. Graft flow reserve recruited by intra-aortic balloon pumping was higher in Y-conduits, regardless of the grafted territory and the perfusion strategy chosen. Failed radial artery bypass grafts did not improve transit-time flow results during 1:1 intra-aortic balloong pumping nor showed any recruitment of graft flow reserve.