The Effects of Preserving Mitral Valve Function on a Left Atrial Assist Device: An In Vitro Mock Circulation Loop Study

We are developing a left atrial assist device (LAAD) to pump blood from the left atrium to the left ventricle for patients who have heart failure with preserved ejection fraction (HFpEF). This study aimed to assess the hemodynamics with the LAAD implanted at two different levels: the mitral valve (MV) level, after removing the MV; and the supravalvular level, preserving MV function conditions using an in vitro mock circulatory loop. Normal heart and mild, moderate, and severe diastolic heart failure conditions were simulated, and the LAAD was set at three different speeds. Without the LAAD support, cardiac output (CO) decreased from 3.7 to 1.1 L/min, aortic pressure (AoP) decreased from 100 to 33 mm Hg, and left atrial pressure (LAP) increased from 16 to 23 mm Hg as the diastolic function became impaired. With high pump support after removing the MV, CO and AoP readings were comparable with those for preserved MV function (CO reached 3.9-4.1 L/min, AoP reached more than 110 mm Hg, and LAP dropped to 16-17 mm Hg under both conditions at high pump speeds). In the mock circulatory loop, our LAAD appeared to have sufficient ability to maintain the hemodynamic status at both positions.