BIO6: Acute In Vivo Studies of the Left Atrial Assist Device and Simulated Diastolic Heart Failure

Abstract

Purpose: The Left Atrial Assist Device (LAAD) is a mixed-flow pump in development for patients who have diastolic heart failure (DHF). The device is implantable in the mitral plane and delivers blood from the left atrium to the left ventricle to mitigate high left atrial pressure. The purpose of this study was to assess the operational in vivo performance of the LAAD with simulated DHF conditions. Methods: The LAAD was implanted in calves (n=8; mean weight 84.5 kg) using cardiopulmonary bypass (CPB) support through a left atrial incision. Various pump-operating conditions, including mean pump speeds ranging from 3,600 to 5,200 rpm and three DHF conditions with a balloon (0, 50 and 70 mL) inflated inside the left ventricle, were tested and evaluated. The hemodynamics for each pump setting were recorded. As for the DHF conditions, the effect of the balloon inflation was evaluated before and after the LAAD implantation in 5 cases (mean weight 89.1 kg) among the 8 calves. Results: The LAAD responded to all control inputs and ran as expected during the experiment. Anatomical fit of the LAAD was suitable for all hearts, but some suction events were occasionally observed at speeds over 4,400 rpm, mainly due to of the small size of the normal left atrium. For the simulated DHF conditions, the baseline data (without LAAD) showed lower cardiac output and aortic pressure (Fig 1A and 1B) and higher LAP and left ventricle end diastolic pressure (Fig 1C and 1D) as the DHF conditions increased in severity. The LAAD seemed to mitigate the severity of the simulated DHF hemodynamics (Fig 1A-D). Conclusion: The acute implantations of the LAADs in calves were successful, and the pump showed improvement of the hemodynamics in the simulated DHF conditions. Additional studies, including chronic evaluations are underway.Figure 1. The in vivo hemodynamics changes under 50 and 70 mL of balloon inflation compared with no balloon inflation. A: Cardiac output (CO), B: Arterial pressure (AoP), C: Left atrial pressure (LAP), and D: Left ventricular end-diastolic pressure (LVEDP).