Studies with the Total Artificial Heart Using Sheep as an Adult Animal Model

The sheep was developed as an adult animal model for artificial heart research at the University of Utah. A JARVIK-7™ pneumatic total artificial heart, designed for human use (stroke volume 100ml), was implanted in 43 sheep from 1980 through 1983. Experimental results from these implanted sheep indicate excellent hemodynamic performance of the pneumatic heart system, insignificant mineralization of the pumping diaphragm, and stable laboratory values and body weight. The longest survival time was 297 days in 1982. The sheep has proven to be a good experimental model for the long-term testing of a total artificial heart. However, because of several problems, the average survival days of these sheep was not consistently extended; 63 days in 1980 (5 cases), 12 days in 1981 (15 cases), 71 days in 1982 (8 cases), and 30 days in 1983 (15 cases). From the analyses of the experimental data of these sheep, as current problems, postimplantation hemolysis, renal failure, pulmonary dysfunction, infection with vegetative thrombus, mechanical accident, and renal infarctions are identified, and the mechanisms of these problems are discussed. Further study is needed to identify the mechanisms to eliminate postimplantation hemolysis, renal failure, and pulmonary dysfunction, to consistently obtain long-term surviving sheep. For long-term survival, prevention of infection is an important factor.
A cardiac output monitor and diagnostic unit (COMDU™) was used for the cardiac output measurement and evaluation of the hemodynamic performance of the ventricles, which proved to be very useful for animal and human application of the pneumatic total artificial heart.