Current status of artificial hearts and ventricular assist devices.

Currently available approaches for patients with refractory heart failure include intravenous inotropic therapy, partial left ventriculectomy, dynamic cardiomyoplasty, mechanical circulatory support, and heart transplantation. Heart transplantation is limited by the availability of donor organs, which is never expected to meet the increasing demand. Numerous devices have been developed for circulatory support. Currently available devices differ in configuration, anatomic location, flow characteristics, and durability. Many devices are currently available for mechanical support, and they can generally be categorized as follows: 1) pulsatile or continuous blood flow; 2) internal (implantable) or external (extracorporeal); 3) pneumatically or electrically powered; and 4) for short-term or long-term support. Proper selection of patients for a given therapy has a major impact on clinical outcome. Early implantation of implantable devices, before the onset of multiple or irreversible end-organ failure, is essential. Short-term devices are indicated if myocardial recovery is anticipated, as in cases of postcardiotomy shock and acute myocarditis. Long-term devices are indicated for transitioning patients with end-stage myocardial failure to heart transplantation. Long-term assist devices may, in some selected cases, serve as an alternative to heart transplantation. This alternative will benefit both patients in chronic heart failure competing for a limited donor supply and patients with contraindications to transplantation, such as advanced age, previous malignancies, and renal dysfunction. The next generation of blood pumps to be applied clinically is likely to be axial pumps, which are valveless, miniaturized, intraventricular left ventricular assist devices.