DESIGN, MANUFACTURING, AND TESTING OF A PARACORPOREAL PULSATILE VENTRICULAR ASSIST DEVICE - SAO-PAULO HEART INSTITUTE VAD

This paper describes the design of a ventricular assist device (VAD), its manufacturing, and testing. The VAD presented is pulsatile, with a free-floating membrane, smooth internal surfaces, and pericardial val ves. It comprehends also a pneumatic driving unit capable of operating in the ''full to empty,'' EKG synchronized or asynchronous modes. In vitro tests were performed to assess its mechanical durability, hydrod ynamic performance, and hemolysis. To optimize cannulas and implant te chniques, we performed in vivo tests in 22 sheep and 8 calves. In thes e tests, we also evaluated hemolysis and the device's capacity to norm alize hemodynamic parameters during induced cardiac failure. The VAD w orked for 4,000 h without failure in a mock circulatory loop. In full to empty mode, it displayed a rate-mediated ''Starling-like'' performa nce. Optimum output was achieved with a systole duration of 40% of the cycle. The in vitro hemolysis index (IH) was 6.7 +/- 2.1. Hemolysis i n animal experiments was clinically nonsignificant. In calves with ind uced cardiac failure, the VAD was able to normalize hemodynamic parame ters within 120 min.