12 December 2008

Artificial heart

The invention: The first successful artificial heart, the Jarvik-7, has helped to keep patients suffering from otherwise terminal heart disease alive while they await human heart transplants. The people behind the invention: Robert Jarvik (1946- ), the main inventor of the Jarvik-7 William Castle DeVries (1943- ), a surgeon at the University of Utah in Salt Lake City Barney Clark (1921-1983), a Seattle dentist, the first recipient of the Jarvik-7 Early Success The Jarvik-7 artificial heart was designed and produced by researchers at the University of Utah in Salt Lake City; it is named for the leader of the research team, Robert Jarvik. An air-driven pump made of plastic and titanium, it is the size of a human heart. It is made up of two hollow chambers of polyurethane and aluminum, each containing a flexible plastic membrane. The heart is implanted in a human being but must remain connected to an external air pump by means of two plastic hoses. The hoses carry compressed air to the heart, which then pumps the oxygenated blood through the pulmonary artery to the lungs and through the aorta to the rest of the body. The device is expensive, and initially the large, clumsy air compressor had to be wheeled from room to room along with the patient. The device was new in 1982, and that same year Barney Clark, a dentist from Seattle, was diagnosed as having only hours to live. His doctor, cardiac specialistWilliam Castle DeVries, proposed surgically implanting the Jarvik-7 heart, and Clark and his wife agreed. The Food and Drug Administration (FDA), which regulates the use of medical devices, had already given DeVries and his coworkers permission to implant up to seven Jarvik-7 hearts for permanent use. The operation was performed on Clark, and at first it seemed quite successful. Newspapers, radio, and television reported this medical breakthrough: the first time a severely damaged heart had been re-placed by a totally artificial heart. It seemed DeVries had proved that an artificial heart could be almost as good as a human heart. Soon after Clark’s surgery, DeVries went on to implant the device placed by a totally artificial heart.in several other patients with serious heart disease. For a time, all of them survived the surgery. As a result, DeVries was offered a position at Humana Hospital in Louisville, Kentucky. Humana offered to pay for the first one hundred implant operations The Controversy Begins In the three years after DeVries’s operation on Barney Clark, however, doubts and criticism arose. Of the people who by then had received the plastic and metal device as a permanent replacement for their own diseased hearts, three had died (including Clark) and four had suffered serious strokes. The FDAasked Humana Hospital and Symbion (the company that manufactured the Jarvik-7) for complete, detailed histories of the artificial-heart recipients. It was determined that each of the patients who had died or been disabled had suffered from infection. Life-threatening infection, or “foreign-body response,” is a danger with the use of any artificial organ. The Jarvik-7, with its metal valves, plastic body, and Velcro attachments, seemed to draw bacteria like a magnet—and these bacteria proved resistant to even the most powerful antibiotics. By 1988, researchers had come to realize that severe infection was almost inevitable if a patient used the Jarvik-7 for a long period of time. As a result, experts recommended that the device be used for no longer than thirty days. Questions of values and morality also became part of the controversy surrounding the artificial heart. Some people thought that it was wrong to offer patients a device that would extend their lives but leave them burdened with hardship and pain. At times DeVries claimed that it was worth the price for patients to be able live another year; at other times, he admitted that if he thought a patient would have to spend the rest of his or her life in a hospital, he would think twice before performing the implant. There were also questions about “informed consent”—the patient’s understanding that a medical procedure has a high risk of failure and may leave the patient in misery even if it succeeds. Getting truly informed consent from a dying patient is tricky, because, understandably, the patient is probably willing to try anything. The Jarvik-7 raised several questions in this regard:Was the ordeal worth the risk? Was the patient’s suffering justifiable? Who should make the decision for or against the surgery: the patient, the researchers, or a government agency? Also there was the issue of cost. Should money be poured into expensive, high-technology devices such as the Jarvik heart, or should it be reserved for programs to help prevent heart disease in the first place? Expenses for each of DeVries’s patients had amounted to about one million dollars. Humana’s and DeVries’s earnings were criticized in particular. Once the first one hundred free Jarvik-7 implantations had been performed, Humana Hospital could expect to make large amounts of money on the surgery. By that time, Humana would have so much expertise in the field that, though the surgical techniques could not be patented, it was expected to have a practical monopoly. DeVries himself owned thousands of shares of stock in Symbion. Many people wondered whether this was ethical. Consequences Given all the controversies, in December of 1985 a panel of experts recommended that the FDAallow the experiment to continue,but only with careful monitoring. Meanwhile, cardiac transplantation was becoming easier and more common. By the end of 1985, almost twenty-six hundred patients in various countries had received human heart transplants, and 76 percent of these patients had survived for at least four years. When the demand for donor hearts exceeded the supply, physicians turned to the Jarvik device and other artificial hearts to help see patients through the waiting period. Experience with the Jarvik-7 made the world keenly aware of how far medical science still is from making the implantable permanent mechanical heart a reality. Nevertheless, the device was a breakthrough in the relatively new field of artificial organs. Since then, other artificial body parts have included heart valves, blood vessels, and inner ears that help restore hearing to the deaf. William C. DeVries William Castle DeVries did not invent the artificial heart himself; however, he did develop the procedure to implant it. The first attempt took him seven and a half hours, and he needed fourteen assistants. Asuccess, the surgery made DeVries one of the most talked-about doctors in the world. DeVries was born in Brooklyn,NewYork, in 1943. His father, a Navy physician, was killed in action a few months later, and his mother, a nurse, moved with her son to Utah. As a child DeVries showed both considerable mechanical aptitude and athletic prowess. He won an athletic scholarship to the University of Utah, graduating with honors in 1966. He entered the state medical school and there met Willem Kolff, a pioneer in designing and testing artificial organs. Under Kolff’s guidance, DeVries began performing experimental surgeries on animals to test prototype mechanical hearts. He finished medical school in 1970 and from 1971 until 1979 was an intern and then a resident in surgery at the Duke University Medical Center in North Carolina. DeVries returned to the University of Utah as an assistant professor of cardiovascular and thoracic surgery. In the meantime, Robert K. Jarvik had devised the Jarvik-7 artificial heart. DeVries experimented, implanting it in animals and cadavers until, following approval from the Federal Drug Administration, Barney Clark agreed to be the first test patient. He died 115 days after the surgery, having never left the hospital. Although controversy arose over the ethics and cost of the procedure, more artificial heart implantations followed, many by DeVries. Long administrative delays getting patients approved for surgery at Utah frustrated DeVries, so he moved to Humana Hospital-Audubon in Louisville, Kentucky, in 1984 and then took a professorship at the University of Louisville. In 1988 he left experimentation for a traditional clinical practice. The FDA withdrew its approval for the Jarvik-7 in 1990. In 1999 DeVries retired from practice, but not from medicine. The next year he joined the Army Reserve and began teaching surgery at the Walter Reed Army Medical Center.