Material and design factors in thromboembolization in total artificial heart recipients living 100-2,000 hours

When total artificial heart (TAH) recipients live over 100 h it is possible to evaluate the thrombogenicity of design and biomaterials. In 20 consecutive TAH recipients of the Jarvik heart with Björk-Shiley valves we compared rough (Dacron fibril-coated Silastic) and smooth (Biomer and Avcothane) blood surfaces. The mean survival times with rough surfaces was 296 h, with smooth surfaces 545 h. The present designs necessitate a sharp angle junction between the diaphragm and housing, creating stagnation areas and turbulences which induce thromboembolization. The valve rings and struts are another constant source of thromboembolism. Of the 80 valves, 41% showed thrombus deposition independent of anticoagulation. The polyurethane surfaces, in contrast to the fibrilized surfaces, were very clean and free of thrombi at autopsy. The thromboembolization was not dependent on anticoagulation and platelet adhesiveness inhibitor in hearts with rough surfaces. Based on 20 experiments including 78- and 94-day TAH survivors (Avcothane and Biomer hearts), there is an indication of the need of a new ventricular design. The ultimate design should generate physiological pulse waves without turbulences or stagnation areas within the device.