Comparison of Hemodynamic and Biomechanics of Direct Ventricular Assist Devices in Various Loading Modes: A Simulation Study

In order to develop an efficient and safe direct ventricular assist device, this study analyzed the effects of compression, torsion, and compression-torsion loading modes on the ventricles. A three-dimensional (3D) dynamic biventricular finite element model of a patient with heart failure (HF) was developed, and three different loading modes of direct ventricular assist devices were simulated to evaluate their advantages by comparing the hemodynamic and biomechanical parameters. For the compression and torsion modes, the range of left ventricular ejection fraction (LVEF) increased from a baseline of 36.2% to a maximum of 47.9% and 40.6%. For the compression-torsion mode, applying a 40 deg torsion angle at 2.5 kPa compression mode increased the LVEF from 40.45% to 43.6%. However, applying a 40 deg torsion angle on the 7.5 kPa compression mode, the ejection fraction decreased from 47.7% to 45.9%. Meanwhile, the maximum principal stresses in the compression mode were generally below 80 kPa, whereas the maximum principal stresses in the multiple nodes of torsion and compression-torsion were greater than 150 kPa. The compression assist mode is more effective and safer than the torsion mode. Applying torsion at lower pressure (2.5 kPa + 40 deg) further increased the output, whereas applying torsion at higher pressure (7.5 kPa + 40 deg) decreased the output of the device. These experiments provide a theoretical basis for the design and optimization of direct ventricular assist devices.