As brave as any real or fictional astronaut, half a dozen men have already undergone implantation with the AbioCor artificial heart. The patients in this clinical trial were literally at death’s doorstep, expected to live less than 30 days had they not received an artificial heart. The first, 59 year old Robert Tool, lived 151 days following his July 2nd, 2001 operation at Jewish Hospital in Louisville, KY (editor’s note: the “first ever” artificial heart implanted was in 1969 at the Texas Heart Institute, with the patient surviving for 60 hours on the artificial pump). The second, 70 year old Tom Christerson, survives following his operation at Texas Heart Institute on September 13th, 2001. The third, Bobby Harrison, survived 121 days following his operation at Texas Heart Institute on Sept. 26th, 2001. The fourth, an unidentified male, survived 56 days following his December 12th, 2001 operation at UCLA. The fifth, James Quinn, survives following his operation at Hahnemann University Hospital of Philadelphia on November 5th, 2001. The 6th to undergo the attempted implantation did not survive the November 27th, 2001 surgery at the Texas Heart Institute. Each of these patients has contributed immensely to medical knowledge.

Unlike its more traditional counterpart, the Jarvik-7, which utilizes pumps and valves driven by external air pressure hoses, the grapefruit-sized AbioCor is meant to be a permanent artificial heart. The completely internalized AbioCor weighs about 3 pounds, and is driven by a 4 pound external lithium battery pack worn on a belt. The battery pack carries a 4 hour charge, or longer with extra batteries. The heart charges continuously through a coil transmission system; a 20 watt power stream is transmitted from coil to coil across the skin, with no wires penetrating the skin. The internal battery (like the internal operating battery in your notebook computer) holds a 30 minute charge, enough for a shower or a change of clothing. Sensors within the AbioCor determine changes in the metabolic demands of the patient, allowing a microprocessor to adjust the heart rate accordingly.

The largely plastic and titanium AbioCor currently costs around $75,000 and at least twice that to implant. It is hoped that eventually this device will be available at a price similar to that of a new car. The AbioCor pumps blood using a high speed internal motor that generates pressure. This pressure forces hydraulic fluid from side to side inside the polyurethane “angioflex” bladders of the two-chambered heart. As one bladder fills, it pushes blood out of the corresponding heart chamber; as the other bladder empties, that chamber of the heart is allowed to fill with blood. Unlike the real heart, in which both sides of the heart pump at once, the two chambers of the AbioCor alternate; the right chamber of the AbioCor pumps blood to the lungs, and then as the right chamber fills with blood, the left chamber pumps blood to the body. An internal microprocessor determines power flow to the heart, monitors heart operation and provides an alarm.

Watch for the AbioCor and BeneCor (possibly the next generation), being jointly developed between Abiomed and Pennsylvania State University, to eventually outperform the real human heart and possibly extend human lifespan.

Dr. W. David Currie