In vivo evaluation of an intrathoracic ventricular assist device

In this series of experiments, the Unified System components of the HeartSaver Ventricular Assist Device (VAD) version 5.0 were isolated from the controller and power supply for independent assessment. Five systems with external controller/power supply via a percutaneous lead configuration were tested in 13 male calves (101.8+/-4.3 kg). Two studies were ended acutely because of improper filling and air embolism, respectively. Duration of support was from 2.2 hours to 30 days (mean, 99+/-62 hours). The 30 day survivor was euthanized electively. Study termination was related to postoperative complications in five calves: two with bleeding/tamponade, one with thromboembolism caused by inadequate anticoagulation, and two with respiratory insufficiency. Other causes of termination were: one caused by main building power failure, two from errors in communication between the device and controller, and two caused by hydraulic fluid loss related to housing defects. From these experiments, an intrathoracic position for the calf has been defined, the procedure for implantation without cardiopulmonary bypass has been developed, refinements to the controller have been made, and inflow and outflow cannulae have been reinforced. Hydraulic fluid losses will be solved by proceeding with use of a titanium housing instead of polyurethane. In conclusion, the development of the HeartSaver VAD is progressing, in part because of these experimental and informative animal studies. Further in vivo evaluation of the final version will be conducted before clinical trials.