Constructional and functional characteristics of recent total artificial heart models TNS Brno VII, VIII, and IX.

Twelve total artificial heart (TAH) models have been developed at the Brno Research Center. Devices VII, VIII, and IX were constructed on the principle of asymmetry. Three main objectives had to be fulfilled by this construction. First, contact of the flap inflow valve with the diaphragm during the pumping cycle had to be avoided. Second, the evacuation regimen of the blood chamber needed to be improved. Third, the danger of thrombi formation due to the lesser incidence of the dead corners had to be decreased or eliminated. The type VII heart has a roof-shaped polyurethane valve in the outflow tract whereas the type VIII heart has a flap valve. The decrease of thrombi incidence around the outflow valve was thus secured, and the driving pressure was decreased as well. In the type IX heart, the small additional flap valve is attached to the outflow valve. In one Brno VII device, Imachi's jellyfish valve has been mounted. Altogether, 62 long-term experiments with survival times of 30-314 days have been performed. To this number, 4 comparative experiments using the Rostock artificial heart were added.