Left Atrial Circulatory Assistance in Simulated Diastolic Heart Failure Model: First in Vitro and in Vivo

Abstract

We are developing a left atrial assist device (LAAD) that is implanted at the mitral position to treat diastolic heart failure (DHF) represented by heart failure with preserved ejection fraction. The LAAD was tested at 3 pump speeds on a pulsatile mock loop with a pneumatic pump that simulated DHF conditions by adjusting the diastolic drive. The LAAD was implanted in 6 calves, and the hemodynamics were assessed. In 3 cases, DHF conditions were induced by using a balloon inserted into the left ventricle, and in 2 cases, mitral valve replacement was also performed after the second aortic cross-clamp. DHF conditions were successfully induced in the in vitro study. With LAAD support, cardiac output, aortic pressure and left atrial pressure recovered to normal values, whereas pulsatility was maintained for both in vivo and in vitro studies. Echocardiography showed no left ventricular outflow tract obstruction, and the LAAD was successfully replaced by a mechanical prosthetic valve. These initial in vitro and in vivo results support our hypothesis that use of the LAAD increases cardiac output and aortic pressure and decreases left atrial pressure, while maintaining arterial pulsatility.