Orthotopic Implantation of the Tether-Free Moving-Actuator Type Total Artificial Heart in Sheep

Summary

An electromechanical total artificial heart (TAH) was developed. Its fitting trials were performed with computer simulations, and we orthotopically implanted it in 60- to 70-kg sheep in tether-free operations. The moving-actuator mechanism in this TAH was adapted to decrease the distance among the four inlet and outlet ports for fitting to human remnants. This TAH has no external compliance chamber, and the left-to-right balance of cardiac outputs is obtained by expansion and compression of 100 ml internal air in the variable volume space and by the asymmetric operation of the cylindrical actuator from the center position between the two blood sacs. An implantable controller measures the motor currents and determines the afterload condition. A transcutaneous energy transmission (TET) system and a transcutaneous information transmission system (TIT) are also implanted, with average power efficiency of 78% at 20–60W load. In the Donovan type mock circulation, the TAH has a cardiac output of 6.51/min at 100bpm, and well-balanced pressure between the left and right atria is obtained at around 15 mmHg. In two acute animal experiments, the TAH was orthotopically implanted in the small chest space of 60- to 70-kg sheep.