Determinants of restricted aorta-coronary bypass graft flow.

Several causes of restricted graft flow in a series of 99 patients could be identified by intraoperative measurements of aorta-coronary graft flow and poststenotic pressure. Mechanical stenosis as well as functional restriction of graft flow caused by competition between vein and native artery flow were noted in cases with a mildly stenotic artery or in cases with multiple coronary stenoses grafted to the same vessel. Also, analysis of regional wall motion showed that graft flow may be restricted when supplying areas with reduced wall motion. Knowledge of preoperative coronary anatomy and left ventricular function and careful intraoperative measurement of graft haemodynamics may aid in distinguishing between technical, functional, and myocardial factors of low graft flow.