[The hemodynamic role of venous valves in aortocoronary bypass]

In this study we investigated the hemodynamic role of venous valves in aortocoronary bypass in increasing anterograde coronary flow. The subjects were mongrel dog weighing between 32 and 60 kg. Three types of aortocoronary model were utilized: rigid, semirigid and elastic. Comparisons were made between the flow and the shape of the curve of coronary flow through the venous graft with competent valves and through arterial graft. Coronary blood flow was measured by using electromagnetic flowmeter with a perivascular cuff transducer. The flow was expressed as the area under the coronary flow curve which is directly proportional to its value. Thirteen experiments were performed in the course of the study, with 31 flow measurements and 124 area-under-the curve calculations. The results of the study show that competent valves in the aortocoronary bypass increase total anterograde flow by preventing retrograde flow at the end systole and the beginning of diastole. This, in turn, provides conditions for an increase in diameter of the vessels of the collateral network and a greater flow through the existing collateral vessels.