As of October 1988 the Thoratec ventricular assist device system was used in 72 heart transplant candidates at 20 medical centers in five countries. All patients were in imminent risk of dying before donor heart procurement, with a mean cardiac index of 1.6 +/- 0.5 L/min/m2 and a pulmonary capillary wedge pressure of 27 +/- 8 mm Hg, in spite of maximal medical therapy. The ventricular assist device system consists of a prosthetic ventricle (Pierce-Donachy design) with a 65 ml pumping chamber, made of Thoratec's BPS-215M polyurethane, appropriate cannulae for atrial or ventricular inflow and for arterial outflow connections, and a pneumatic drive console. The devices can be used for partial or complete support of the pulmonary and systemic circulations. Fifty-eight (81%) of the 72 patients received biventricular devices and 14 received support only on the left side of the heart. Average flow rate was 5.0 +/- 0.7 L/min on the left side and 4.3 +/- 0.7 on the right. Fifty-four patients (75%) recovered sufficiently to undergo heart transplantation after a median of 4.4 days (mean, 14.3 days; range, 8 hours to 81 days), and 45 of them have been discharged from the hospital (83% early posttransplant survival and 63% overall survival from implant to discharge). Of 14 patients supported for more than 30 days, 11 underwent heart transplantation, and nine were discharged alive. The actuarial 1- and 2-year posttransplant survival rates are 78% and 75%. We conclude that these heterotopic prosthetic devices provide an effective method of maintaining blood flow to vital organs until a donor heart can be procured.(ABSTRACT TRUNCATED AT 250 WORDS)