抄録
In the left heart bypass in which blood is withdrawn from the left atrium and pushed into a artery by a roller pump, the pulse pressure of arteries decreases in proportion to increase of bypassed blood flow. And peripheral circulatory failure occurs if the bypass is prolonged. Although blood is usually ejected in diastole of the heart in the left heart bypass using a pulsatile pump, it is better to eject it in systole when we think much of augmentation of pulse pressure and improvement of peripheral circulation. We examined how much the after-load to the heart increased in case blood is ejected in systole by measuring hemodynamic change and myocardial oxygen consumption.
Method) In mongrel dogs left heart bypass was instituted by inserting the cannulae to the left atrium and the left femoral artery. The coronary sinus was also canulated through the right atrial wall to sample out coronary sinus blood and measure the blood flow. Result) (1) The pulse pressure of arteries in steady-flow bypass group was 43% of that in control group, 82% in diastolic ejection group, 105% in systolic ejection group. (2) The end-diastolic pressure of the left ventricle was lower than that of control group even in systolic ejection group. It was in diastolic ejection group that the lowest pressure was recorded. (3) Myocardial oxygen consumption was about two thirds of that of control group in both steady-flow bypass group and diastolic ejection group. On the other hand it slightly increased (72%) in systolic ejection group, but was significantly lower as compared to that in control group.
