In vivo evaluation of the biocompatibility of the totally implantable ventricular assist device (HeartSaver VAD)

A series of multicenter in vivo studies have been conducted to assess the biocompatibility and device performance of the HeartSaver VAD, a totally implantable pulsatile ventricular assist device (VAD). The experiments (n = 23) were conducted in calves with a mean weight of 101 (75-152) kg. Implants took place at four centers using two different surgical procedures of implantation (one with cardiopulmonary bypass and one without). Three anticoagulation regimens were used (one with continuous intravenous heparin, one with oral warfarin, and one with oral warfarin combined with antiplatelet clopidogrel therapy). Device function and biochemistry were monitored during the study, and organs and device analysis were conducted at explant. There were six nonsurvivors because of early surgical complications (during the first week of support). The postoperative courses in the remaining 17 (74%) calves were uneventful. Hemodynamic and biocompatibility indicators were monitored throughout the study. The mean duration of device support for those cases was 48 (13-92) days. Mean device flow was 7.15 (+/-1.68) L/min. There were no deaths caused by infection; however, two animals developed endocarditis believed to be caused by the percutaneous instrumentation lines used for the study. No severe bleeding requiring reoperation occurred during the study. The mean plasma free hemoglobin was within normal limits at 6.8 +/- 2.6 mg/dl. Renal and hepatic functions were normal with a mean creatinine of 0.6 +/- 0.1 mg/dl and a mean aspartate aminotransferase of 68.7 +/- 42.6 mg/dl. Several device related improvements were identified and have now been implemented. Additional bovine implants with an optimized device are currently underway in preparation for human trials.