In vivo evaluation of an intrathoracic ventricular assist device

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