STATUS OF MAGNETICALLY SUSPENDED MiTiHeart?? LVAD

Abstract

The MiTiHeart® LVAD is a non-pulsatile rotary blood pump that uses a hybrid passive/active magnetic bearing support system and exhibits low-hemolysis, low power loss, low vibration, and high reliability. Unique features include a simple and direct flow path for both main and washing blood flows, non-contact pump rotor, i.e., no rubbing surfaces, and relatively large clearances between the pump rotor and housing. The first prototype was constructed from medical grade polycarbonate. To reduce the possibility of thrombosis, the internally exposed surfaces were coated with a biocompatible polymer. Hemolysis testing, with bovine blood, was performed at the Hershey Medical Center at Pennsylvania State University. Test results showed a low normalized index of hemolysis of 0.01 mg/100 L. An acute animal test and a chronic 200-hour implant were successfully completed at the Hershey Medical Center. In these tests, the pump was implanted in a calf and operated in parallel with the heart A second prototype was constructed using a titanium alloy for all blood contacting surfaces and incorporating a redundant hydrodynamic thrust bearing. This addition; however, required careful assessment of blood flow and potential hemolysis in narrow passages. A novel methodology, which combines the existing hemolysis models with the principles of fluid dynamics for quantitative prediction of the rate of blood damage was used. A second prototype was implanted in a calf in a chronic test. The results of this evaluation plus results of in vitro performance tests will be presented