Safety validation study of the hybrid membrane in the Carmat bioprosthetic Total Artificial Heart

Introduction The Carmat bioprosthetic Total Artificial Heart (C-TAH) is a mechanical circulatory support device providing an alternative to the heart transplant for patients in advanced heart failure. Objectives One of the most original components of the C-TAH is its biocompatible hybrid membrane made of bovine pericardial tissue and polyurethane separating the actuating liquid of the pump from blood inside ventricles. The aim of our study is to evaluate safety of the hybrid membrane in terms of mechanical aging, risks of calcification, and impact on the hemodynamics inside ventricles on red blood cells, platelet and von willebrand factor (vWF) impairment. Methods Hybrid membranes were aged in a custom-designed endurance bench then evaluated in terms of mechanical proprieties and physical degradation. Erosion areas were explored in electronic microscopy and surface topography. Samples were subcutaneously implanted in Wistar rats as a model for calcification. Hemodynamic simulation using computational model has been used to reproduce shear stress in both ventricles. Results Compliance of the membrane is not significantly modified from 9 month to a 4 years aging simulating process. Physical proprieties as glass transition temperature and infrared spectrum are not modified. Exploration of erosion areas showed no oil diffusion through the membrane. Implantation in wistar rats demonstrated that anticalcification pretreatment with FET was able to significantly reduce the calcium concentration. We confirmed the absence of calcification in the areas in contact with blood by microtomography in the feasability study. The hemodynamic simulation showed no significant stress able to trigger hemolysis, platelet activation or the degradation of the vWFmultimers, confirmed with the patients implanted in feasibility study. Conclusion Mechanical aging, calcification model and hemodynamic simulation allowed us to confirm safety of the hybrid membrane used in the C-TAH.