Continuous flow left ventricular pump support and its effect on regional left ventricular wall stress: finite element analysis study

Abstract

Left ventricular assist device (LVAD) support unloads left ventricular (LV) pressure and volume and decreases wall stress. This study investigated the effect of systematic LVAD unloading on the 3-dimensional myocardial wall stress by employing finite element models containing layered fiber structure, active contractility, and passive stiffness. The HeartMate II(®) (Thoratec, Inc., Pleasanton, CA) was used for LV unloading. The model geometries and hemodynamic conditions for baseline (BL) and LVAD support (LVsupport) were acquired from the Penn State mock circulatory cardiac simulator. Myocardial wall stress of BL was compared with that of LVsupport at 8,000, 9,000, 10,000 RPM, providing mean pump flow (Q(mean)) of 2.6, 3.2, and 3.7 l/min, respectively. LVAD support was more effective at unloading during diastole as compared to systole. Approximately 40, 50, and 60% of end-diastolic wall stress reduction were achieved at Q(mean) of 2.6, 3.2, and 3.7 l/min, respectively, as compared to only a 10% reduction of end-systolic wall stress at Q(mean) of 3.7 l/min. In addition, there was a stress concentration during systole at the apex due to the cannulation and reduced boundary motion. This modeling study can be used to further understand optimal unloading, pump control, patient management, and cannula design.

Partial LVAD Restores Ventricular Outputs and Normalizes LV but not RV Stress Distributions in the Acutely Failing Heart in Silico

“…The most dramatic improvement, however, was seen in the reduction of pressure, chamber size and stress in the LV at ED. The reduction in chamber size and LV preload due to LVADs is well established in clinical findings ( 33 , 34 ) and other numerical investigations ( 18 , 32 , 35 ).…”

Biomechanics of Cardiac Function

“…Clearly, a knowledge of mechanical engineering is needed to design and build these pumps, but it is also important to understand the ways in which LVADs alter the mechanics of the heart. LVADs modulate the wall stresses in the myocardial tissue, but also the flow patterns of the blood through the heart and into the aorta which can lead to clinical complications (21, 88) LVADs decrease the filling pressure and mechanical load on the ventricle which can reduce adverse remodeling (51). It has been shown that LVAD devices can reduce the expression of MMP-1 and MMP-9, increase the expression of TIMP-1 and TIMP-3, and decrease the expression of NF-κB (59, 109), Further, LVAD therapy has been shown to prevent myocyte hypertrophy (8).…”

Computational analysis of the hemodynamic characteristics under interaction influence of β-blocker and LVAD

“…LVAD is found to reduce myocardial force by pumping blood out of the left ventricle. Jhun et al [ 32 ] investigated the changes in myocardial force under LVAD support by using computational fluid dynamic analysis (CFD). He found that the myocardial force under LVAD support was significantly reduced.…”