Current status on the development of a totally implantable biventricular assist device: the Baylor Gyro BVAD.

OBJECTIVE: The Baylor Gyro BVAD is under development with the final goal of establishing a totally implantable biventricular assist system (BVAD). The aim of this study was to evaluate the safety, reliability, and effectiveness of the device in a long-term in vivo model. METHODS: The BVAD was implanted into eight calves for longer than 4 weeks in a biventricular bypass fashion, with the native heart remaining. Pump performance was assessed with the system's digital data acquisition unit. Postoperatively, anticoagulation was maintained with i.v. heparin perfusion (ACT< or = 250 sec) gradually replaced by coumadin. Treadmill exercise tests were performed daily following a 10-day reconvalescence period after surgery. RESULTS: The animals were kept alive for 37-90 days. The pumps yielded average flows of 5.3 +/- 1.1 l/min and 4.9 +/- 0.7 l/min for the LVAD and RVAD, respectively. Power consumption was 8.2 +/- 2.7 W and 9.6 +/- 4.7 W at 1935 +/- 123 rpm and 2015 +/- 365 rpm, respectively. All cases exhibited low hemolysis; renal and liver function were kept normal throughout the experiments. The animals demonstrated no thromboembolic neurological symptoms and tolerated moderate treadmill exercise. CONCLUSION: The Baylor Gyro BVAD demonstrated effective and reliable in vivo performance with acceptable biocompatibility. Based on these studies, we conclude that the system will be suitable as a long-term totally implantable BVAD for uses intended for longer than two years.