[The artificial heart: present status and future prospects]

Artificial heart (AH) and heart transplantation (HTx) are complementary means of cardiac assistance and replacement. Temporary use AH including ventricular assist systems (VASs) and total artificial hearts (TAHs) have been put into clinical use. VASs applied to 848 patients in the world and 187 in Japan with acute profound heart failure. The short-term survival rates are 23.3% and 27.3%, respectively. HTx has become an accepted therapeutic procedures. To date, 255 patients received VAS and 182 received TAH as a bridge to HTx, because the number of candidates exceeds the supply of donor hearts. Long-term implantable AH is the future alternatives for cardiac replacement. It is recognized that several key components will be necessary for development of an AH with high performance including biomaterial with antithrombogenecity and durability, an implantable actuator, a noninvasive monitoring system and sensors, a miniature auto-control system, and an energy converter. Another types of devices are on the horizon. These are a muscle-powered biomechanical AH, an AH powered by artificial muscle, and an integrated artificial heart-lung device. With remarkable progress in medicine and engineering, we can expect to see totally implantable permanent use cardiac assist and replacement devices as an alternative for HTx in the near future.