Concomitant aortic valve replacement and coronary bypass: the effect of valve type on the blood flow in bypass grafts

Abstract

In cases of aortic valve replacement, the downstream flow profile and turbulence in the ascending aorta differ according to the prosthetic aortic valve implanted. The objective of this work is to study the influence of prosthetic valve type on the flow in the bypass grafts implanted to the ascending aorta in cases of concomitant aortic valve replacement and coronary artery bypass. The study is conducted on 456 patients receiving concomitant aortic valve replacement and coronary bypass vein grafts anastomosed to the ascending aorta. The patients included in the study received a total number of 725 vein grafts, 249 biological aortic valves and 207 mechanical aortic valves. Intraoperative transit time flow measurement was done for all bypass grafts and a multiple regression model was calculated for the factors influencing the flow in the bypass grafts. The mean flow in vein grafts in patients receiving biological valves was 49.79+/-26.88 ml/min, while in patients receiving mechanical valves it was 46.54+/-26.68 ml/min. The multiple regression model revealed that receiving a mechanical valve is an independent risk factor for lower flow in the vein grafts. The type of the aortic valve implanted and consequently the downstream flow profile in the ascending aorta do affect the flow in the vein grafts in cases of concomitant aortic valve replacement and coronary bypass. Receiving a mechanical aortic valve is an independent risk factor for lower flow in the vein grafts.