Retrieval analyses of U-100 Total Artificial Heart blood-contacting surface

Abstract

This paper deals with retrieval analyses of the Utah-100 (U-100) total artificial heart (TAH). Thrombus formation, cell adhesion and activation, mineralization, and adsorbed protein layers have been investigated on blood-contacting surfaces of the U-100 TAH. Six ventricles were implanted in two calves (7, 97 days) and a sheep (21 days). Six locations on each ventricle (atrial sewing cuff, inflow and outflow diaphragm-housing (D-H) junction, dome of diaphragm, dome of housing, and outflow graft) were systematically analyzed by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) was used to measure the thickness and the distribution of adsorbed proteins (albumin, IgG, and fibrinogen) on the blood-contacting surface. The technique used to visualize each plasma protein involved the immunoperoxidase method. A large saddle thrombus was detected in the 97-day calf, and multifocal renal infarcts were evident in both calves. A small red thrombus was detected only in the LA cuff in the 7-day calf. Other than this, there was no intra-device thrombosis. SEM pictures of diaphragms and housings showed fairly clean surface morphology with minimal platelet adhesion or activation, and minimal fibrin formation or microthrombi, independent of implantation periods. At 97 days, mineralization was detected using energy dispersive X-ray microanalysis (EDAX) along the D-H junctions, and pannus formation was evident on the arterial sewing cuff and the outflow graft. The protein layer thickness on the diaphragm increased with implant time, and the dominant proteins detected on the surface were fibrinogen and IgG, rather than albumin.