The present and future of cardiac assist devices

This article describes the status of development of an implantable electrically powered ventricular assist device designed for a minimum of a 2-year operation in patients with advanced heart failure. While these devices are envisioned for chronic support of the failing circulation, air-driven blood pumps have been used to provide life support to patients with acute ventricular dysfunction produced by a reversible myocardial injury of unknown origin. The physical and hemodynamic characteristics of the mechanical circulatory support devices are detailed. Clinical indications and results are provided on patients treated with temporary ventricular assist devices. Long-term follow-up of some patients has demonstrated sustained improved cardiac function for up to 5 years after treatment. Reperfusion injury and postischemic myocardial depression are discussed as two possible etiologies of acute ventricular dysfunction. In the summer of 1984, investigators began a collaborative program to test the engineering reliability of implantable devices as well as their performance in animals. This 3-year Device Readiness Program had a goal of demonstrating an 80% reliability with a confidence interval of 70%. In the future, the implantable device will be evaluated clinically in selected patients to investigate its ability to support circulatory functions and the results of host-device interactions. These devices have potential both as experimental tools in studies of heart and vascular disease and in the treatment of patients with intractable heart failure.