Right-left ventricular balance in implanted electrically powered artificial hearts

An electrohydraulic total artificial heart (EHTAH), using an interatrial shunt (IAS) for right-left heart balance, was evaluated in acute, in vivo, open-chested calves. The EHTAH system demonstrated physiologic autoregulation with Starling-like responsiveness to preload. Output varied from 4 to 9 L/min, as right atrial pressure increased from 3 to 15 mmHg. Device output was minimally influenced by afterload. The efficacy of an IAS to balance the EHTAH was demonstrated over a wide range of preload and afterload conditions. Interatrial shunt flow rates, reflective of the degree of right-left imbalance, varied from 2% to 14% (IAS flow from left to right) of cardiac output. Left atrial pressures typically did not exceed right atrial pressures by more than 6-8 mmHg using an instrumented vascular graft such as the IAS. The simplicity and distinct anatomic, surgical, and engineering advantages of the IAS approach to right-left balance of implanted electrically powered artificial hearts justify further development toward a reliable long-term design.