Abstract
A peristaltic bypass type of left heart assist device, which diverts blood from the left atrium directly to the aorta, has been designed for human adults and large animals such as calves.
This device has two outstanding features. It has no valve in the conventional sense, but is in reality an avalvular pump in which the successive pumping of six pumping chambers simulates valve action. Also, when pumping during diastole of the natural heart, the device is pumping and simultaneously filling when blood is most readily available in the left atrium.
Acute calf experiments demonstrated marked changes in bypass flow, aortic root flow, left ventricular pressure, and left ventricular work during assist pumping. When all six chambers were used at 1:1 trigger ratio, complete atrialization of the left ventricle was achieved.
Continuous synchronous assisted circulation has been performed in calves up to three weeks. Bypass flow was 2.7l/min on an average and 3.8l/min in satisfactory cases. Our device was made all in one-piece out of Silastic, not including a conventional type of valve. No thrombus formation was noted on the pure Silastic surface inside the device when it was properly treated. Hematological studies showed hemolytic tendency caused by mechanical pumping, only for several day after surgery. Biochemical studies did not show any significant changes particularly related to the pumping fashion of the device used.
