Assessing the resistance to calcification of polyurethane membranes used in the manufacture of ventricles for a totally implantable artificial heart.

Abstract

Ventricles made from segmented polyurethane membranes and used in the fabrication of a totally implantable artificial heart are known to undergo biomaterial-associated calcification. As there is no effective method currently available to prevent such biomaterials from calcifying, a practical solution is to use only materials with a relatively high resistance to calcification, to extend ventricular durability and ensure a longer functional life for the manufactured device. In the present study, an in vitro calcification protocol was used to determine the relative resistance to calcification of six different polyurethanes, namely, Carbothane PC3570A, Chronoflex AR, Corethane 80A, Corethane 55D, Tecoflex EG80A, and Tecothane TT1074A. The results demonstrated that all six polyurethanes did become calcified during the 60-day incubation period in the calcification solution. The degree of calcification was found to be associated with the surface chemistry of the particular polyurethane, with the Tecothane TT1074A exhibiting the highest level. The Corethane 80A and 55D polymers showed a relatively low propensity to calcify. These two membranes can, therefore, be considered as the most appropriate materials for the fabrication of ventricles for a totally implantable artificial heart. In addition, since the calcification occurred primarily at the surface of the membranes, without affecting the bulk microphase structure, the issue of modifying the surface chemistry to reduce the incidence of calcification is discussed.