Tomasu heart in goat: Analysis of cause of death

Summary

From 1982 to 1989, 24 Tomasu Total Artificial Hearts were implanted in goats at Kobe City General Hospital. The longest survival was 8 days with a mean of 2 days. The causes of death were classified into three categories:

• 1. Mechanical failure of the total artificial heart (TAH). A valve sticking at the mitral position was noticed in one case, which showed temporary low cardiac output and accompanying high pressure in the left atrium. Three cases had mismatches in size between the TAH and the chest cavity. Two of them survived after partial rib resection. One goat died from compression of the right atrium followed by low cardiac output.

• 2. Technical failure at surgery. Bleeding was the cause of death in 6 cases (25%). It was rare in the later cases as result of new interventions for hemostasis.

• 3. Imperfect planning of the experiment. This included the problem of whether the goat is a suitable animal for TAH implantation or not. The question arose from many complications which could not be explained well by our knowledge of the physiology of the animal. It was most probable that extracorporeal circulation (ECC) for longer than 2 hours was not safe for the animal. Trouble concerning ECC was apparent in 3 animals which had poor recovery from anesthesia. One of them went on to cerebral death.

Other causes of death included pulmonary complications in 5, abdominal distension in 2, and renal failure in 1 goat. We do not yet feel confident of an ECC protocol for goats.