Hemodynamic effects of venous valves in aorto-coronary bypass grafts

Use of the saphenous vein in aorto-coronary bypass surgery for treatment of occlusive coronary artery disease is a well-established technique. Use of the mammary artery for the same purpose has also been favorably reported. This study was undertaken to determine whether a vein graft containing a valve would have an added advantage. A comparison of the effect of competent and incompetent valves in vein grafts on the hemodynamics of coronary circulation was made. In a group of 18 dogs, a 5 cm. portion of each dog's cephalic vein containing a valve was used in a single aorto-coronary bypass graft. Flow measurements were made between the valve and the anastomosis of the graft to the left anterior descending coronary artery (LAD). The valve was made temporarily incompetent by the insertion of a spring wire basket, 3.5 mm. in diameter, through the valve via a side branch. The flow of blood through the venous graft with the competent valve was 11.0 +/- 2.6 per cent higher than with the incompetent valve. An analysis of flow patterns showed that this increased flow could be attributed to a reduction of backflow during systole and an increase in forward diastolic flow. Results suggest that postoperative myocardial perfusion is enhanced by the presence of valves in aorto-coronary bypass vein grafts.