ACCOMODATION OF LEFT-RIGHT IMBALANCE WITH AN INTERATRIAL SHUNT IN AN ELECTROHYDRAULIC TOTAL ARTIFICIAL HEART

Abstract

We evaluated the basic performance of an interatrial shunt (IAS), which was made by punching a hole in the atrial septum, in accommodating the left-right imbalance in our electrohydraulic total artificial heart (EHTAH) system. In an in vitro study conducted in a closed mock circuit connected with the EHTAH, the interatrial pressure gradient changed in proportion to the amount of bronchial flow and the size of the IAS. The IAS of 4.4mm in diameter or larger maintained the interatrial pressure gradient within physiologically permissible limits when the amount of bronchial flow was 5% of cardiac output or less. A left-to-right one-way valve made of a piece of pericardium, a possible option in our IAS method, successfully prevented right-to-left reverse shunt flow through the IAS. In a chronic in vivo study using a calf implanted with the EHTAH for 10 days, a 4.5mm IAS without the one-way valve demonstrated satisfactory dynamic left-right balancing capacity with a stable interatrial pressure gradient of 4±1mmHg over a wide range of atrial pressures. No thrombus was found in or around the IAS at autopsy. We conclude that the IAS is a simple and promising means of left-right balancing in the EHTAH system