Clinical choices for circulatory assist devices. Approximately 1.0% of open heart surgery patients become unweanable from cardiac bypass during the surgical procedure. In addition, nearly 20% of patients accepted for cardiac transplantation die while waiting for a donor heart. Pulsatile pneumatic ventricular assist devices (VADs) provide a realistic solution to these dilemmas. Currently, there are five manufacturers who are competing for the major market share in the clinical use of these devices. Novacor, Thermetics, Thoratec, Symbion, and Abiomed all have competitive VAD systems. Because no one system is optimal for all patients, the limitations, similarities, and strengths of each system should be known to enhance the patient's outcome when using these devices. Successful use of VAD systems, either as a bridge to transplantation or to ventricular recovery, is best approached by adherence to strict patient selection. Once instituted, VAD management centers on detailed attention to anticoagulation and prompt diagnosis and treatment of various complications. 