In vitro testing of a new driver for the pneumatic total artificial heart with inherent cardiac output measuring system.

Based upon the Utah pneumatic driver, a new model for use in animal experiments was designed. It enabled measurement of cardiac output, optimal percentage of systole as well as diagnosis of some of the causes of the decrease of cardiac output of the pneumatic total artificial heart, such as valvular stenosis due to pannus formation. This driver is based on the expansion of a known amount of 'driving-air' during the systolic period. In the calculation of the cardiac output, the in vitro experiments yielded an error range of +/- 3.5%. The analysis of the driving-air pressure tracing during its decompression (systolic period) gave accurate information about the optimal percentage of systole for each frequency and the inflow and outflow resistances.