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An artificial heart is a Prosthetic Device that is implanted into the body to replace the biological Heart . It is distinct from a Cardiopulmonary Bypass machine (CPB), which is an external device used to provide the functions of both the heart and the Lung s. The CPB oxygenates the blood, so does not need to be connected to both blood circuits. Also, a CPB is only suitable for a few hours use, while artificial hearts have been used for periods longer than a year (as of 2007 ). ORIGINS A synthetic replacement for the heart remains one of the long-sought Holy Grail s of modern medicine. The obvious benefit of a functional artificial heart would be to lower the need for Heart Transplant s, because the demand for donor hearts (as it is for all organs) always greatly exceeds supply. Although the heart is conceptually simple (basically a Muscle that functions as a pump), it embodies subtleties that defy straightforward emulation with synthetic materials and power supplies. Consequences of these issues include severe Foreign-body Rejection and external batteries that limit patient mobility. These complications limited the lifespan of early human recipients to hours or days. EARLY DESIGNS A Heart-lung Machine was used in 1953 during the first successful open heart surgery. Dr. John Heysham Gibbon performed the operation and developed the heart-lung substitute himself. Whether this device could be considered as an artificial heart is a subject of debate. The first patented artificial heart was invented by Paul Winchell in 1963. Winchell subsequently assigned the patent to the University Of Utah , where Robert Jarvik ultimately used it as the model for his Jarvik-7. Jarvik's designs improved the device, but his patients succumbed after brief trials. His first Jarvik-7 patient, 61-year-old retired dentist Barney Clark, survived for 112 days after it was implanted at the University of Utah on December 2 , 1982 . One of the innovations of the Jarvik-7 was the inner coating of rough material, developed by David Gernes. This coating helped the blood to clot and coat the inside of the device, enabling a more natural blood flow. After about 90 people received the Jarvik device, the implantation of artificial hearts was banned for permanent use in patients with heart failure, because most of the recipients could not live more than half a year. However, it is used temporarily for some heart transplantation candidates who cannot find a natural heart immediately but urgently need an efficiently working heart. Hiroaki Harasaki of the Cleveland Clinic developed two important improvements for the artificial heart and projected future artificial organs. The two patented inventions solved major obstacles for any fully implanted artificial organs and materials. The first was a non-clotting surface material which significantly reduces the risk of rejection of the organ by the patient's immune system. The second development, which required the collaboration of many disciplines, was an implantable power source which does not create tissue-damaging heat. RECENT DEVELOPMENTS On July 2 , 2001 , Robert Tools received the AbioCor Implantable Replacement Heart produced by the AbioMed company of Danvers, Massachusetts . It was the first completely self-contained artificial heart transplant. The surgery was done by University Of Louisville doctors at Jewish Hospital in Louisville, Kentucky . Tom Christerson survived for 17 months after another AbioCor transplant. On September 6 , 2006 the AbioCor device became the first fully implantable artificial heart to be approved under 'Humanitarian Use Device' rules. FDA Approves First Totally Implanted Permanent Artificial Heart for Humanitarian Uses at FDA.gov The 'CardioWest' temporary Total Artificial Heart (TAH‑t) was developed from the Jarvik-7 by , and has also been approved by the CE . The TAH-t is used only in patients with end stage biventricular failure as a way to improve life expectancy while they are waiting for a heart transplant. In a pivotal clinical study, these patients were successfully transplanted 79% of the time; Cardiac replacement with a total artificial heart as a bridge to transplantation at the National Institutes of Health, One-year and five-year survival rates after heart transplant among these patients were 86 and 64 percent. The longest TAH‑t implantation so far went 620 days (20.4 months). Current status of the total artificial heart at Elsevier.com There are several medical centers where this device can be implanted: |
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