Current status of artificial hearts and ventricular assist devices

Currently available approaches for patients with refractory heart failure i nclude intravenous inotropic therapy, partial left ventriculectomy, dynamic cardiomyoplasty, mechanical circulatory support, and heart transplantation . Heart transplantation is limited by the availability of donor organs, whi ch is never expected to meet the increasing demand. Numerous devices have b een developed for circulatory support. Currently available devices differ i n configuration, anatomic location. flow characteristics, and durability. M any devices are currently available for mechanical support, and they can ge nerally 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 se lection of patients for a given therapy has a major impact on clinical outc ome. Early implantation of implantable devices, before the onset of multipl e or irreversible end-organ failure, is essential. Short-term devices are i ndicated if myocardial recovery is anticipated, as in cases of postcardioto my shock and acute myocarditis. Long-term devices are indicated for transit ioning patients with end-stage myocardial failure to heart transplantation. Long-term assist devices may, in some selected cases, serve as an alternat ive to heart transplantation. This alternative will benefit both patients i n chronic heart failure competing for a limited donor supply and patients w ith contraindications to transplantation, such as advanced age, previous ma lignancies, and renal dysfunction. The nest generation of blood pumps to be applied clinically is likely to be axial pumps, which are valveless, minia turized, intraventricular left ventricular assist devices.