Background The implantable left ventricular assist device (LVAD) was designed to provide circulatory support as an alternative to heart transplantation or to continued medical therapy of end-stage heart failure. Initial experience with the implantable LVAD used as a bridge to heart transplantation provides a clinical opportunity to study the function of the device and adaptation by the patient.Methods and Results Nineteen heart transplant candidates (mean age, 50 years; 17 males) underwent insertion of the HeartMate LVAD as a bridge to heart transplantation from December 1991 to November 1993.All patients were in cardiogenic shock on inotropes, and 16 (84%) were on an intra-aortic balloon pump. Three patients died because of multiple organ failure; all had right ventricular (RV) dysfunction (2 required RV assist devices). Sixteen patients (84%) improved markedly and were rehabilitated to New York Heart Association functional class I-II. Three patients are still on support. Significant improvements in hemodynamic function (based on analysis of the percent change from pre-LVAD condition to pretransplantation) were observed: cardiac index rose from 1.6+-0.2 to 3.2+-0.9 L/min per m21100 patient days of support.1 year) was not tested, so questions regarding long-term device reliability and the chronic risk of infection are unknown. (Circulation. 1994;90(part 2): II-83-II-86.)