Computational analysis of the importance of flow synchrony for cardiac ventricular assist devices.

This paper presents a patient customised fluid-solid mechanics model of the left ventricle (LV) supported by a left ventricular assist device (LVAD). Six simulations were conducted across a range of LVAD flow protocols (constant flow, sinusoidal in-sync and sinusoidal counter-sync with respect to the cardiac cycle) at two different LVAD flow rates selected so that the aortic valve would either open (60mLs(-1)) or remain shut (80mLs(-1)). The simulation results indicate that varying LVAD flow in-sync with the cardiac cycle improves both myocardial unloading and the residence times of blood in the left ventricle. In the simulations, increasing LVAD flow during myocardial contraction and decreasing it during diastole improved the mixing of blood in the LV cavity. Additionally, this flow protocol had the effect of partly homogenising work across the myocardium when the aortic valve did not open, reducing myocardial stress and thereby improving unloading.