IntraVAD, an intra-ventricular assistive device for heart failure patients: design and proof of concept simulations.

摘要

Ventricular assistive devices are approved by Food and Drug Administration as an alternative to heart transplant for congestive heart failure patients. Unlike other devices requiring open-heart surgery, thin active flexible membrane of IntraVAD, made of ionic polymer-metal composites and shape memory alloys (SMA), enables transcatheter implantation and eliminates thoracotomy. Actuation mechanism of the device mimics the natural motion of the heart, applies almost no shear stress on blood cells, and leaves no stagnant points. Hence, it reduces hemolysis and thrombosis risks. The first step in designing the device is defining the objectives based on hemodynamics of eligible patients. A 3-dimensional model is extracted from magnetic resonance images of a subject to provide a precise representation of the inner shape of the ventricle. Numerical solution to the mathematical model of the behavior of ionic polymer-metal composites is then used to check their compliancy with the objectives. Different actuator designs are evaluated to perform the desired motions and address the cardiac insufficiency. Using an iterative design and simulation process, various geometric and material parameters affecting the performance of the device are optimized, including those of the antagonistic two-way SMA actuators. Although methods and results provided here are for the left ventricle, the same are also applicable to the right ventricle.