Effects of competitive blood flow from differently stenotic coronary artery on internal mammary artery graft flow

Objective:To study the effects of competitive blood flow from differently stenotic coronary artery on internal mammary artery graft flow.Methods: Coronary artery bypass grafting(CABG) was conducted in 15 Chinese miniswines using left internal mammary artery(LIMA) anastomosed to left anterior descending artery(LAD).The proximal LAD was mad differently stenotic(0%,30%,50%,75%,90% and 100%) through a flow occlusion and the mean flow of LIMA and LAD proximal and distal to the anastomosis were respectively measured through the transit time flow measurement(TTFM).Results:The mean flow of LIMA was(9.75±1.45),(11.63±1.69),(15.63±2.26),(19.75±2.37),(23.50±2.34) and(26.75±2.11)ml/min,respectively.The mean pulsatility index(PI) value was respectively 4.4±1.7,4.1±1.6,4.2±1.9,3.7±1.8,3.3±1.6 and 2.5±1.4.The mean flow of LIMA when the stenosis of the proximal LAD was 90% or 100% was significant higher than that of LIMA when the stenosis of the proximal LAD was 0%,30% or 50%(P0.01).When the proximal LAD was not fully occluded,there were dual flow in LIMA.There were no difference in LAD flow distal to the anastomosis.Conclusion: The competitive flow from patent LAD does exist and has important effects on IMA graft flow and may be an important cause of IMA graft failure.