Two research teams reported the study, which included four British patients. Three of them are still alive after an average of 3 months from implantation of the device. All were considered ineligible for heart transplants due to their age and poor kidney function.
The device includes the pump itself and a battery pack that lasts eight hours between recharges. The pack is worn at the waist or carried in a small shoulder bag. The batteries are attached through a cable that plugs into a small pedestal-shaped electrical unit implanted in the skull behind the ear. The pump has a small controller box that can be use to adjust for high and low activity levels.
One patient, the second to get the device, developed a brain hemorrhage under the electrical pedestal. Although the hemorrhage was successfully treated, he remained on a ventilator, suffered right heart failure and died about three months after receiving the pump. Subsequently, skull thickness was measured by computerized tomography and the surgical technique was modified to prevent such penetration.
The other patients went home three to eight weeks after receiving the pump and returned to normal activities. There were no infections or blood clots reported in or near the device.
“This small, simple, safe pump can be implanted with little or no time on a heart-lung machine. It poses very little risk and can boost the patient’s native heart function,” says O.H. “Bud” Frazier, M.D., chief of cardiopulmonary transplantation and director of surgical research at the Texas Heart Institute and chief of transplant services at St. Luke’s Episcopal Hospital in Houston. The device, called the Jarvik 2000, was implanted by a team led by Stephen Westaby, Ph.D., MS, FETCS a consultant cardiac surgeon at John Radcliffe Hospital in Oxford, England. Jarvik Heart, Inc., and the Texas Heart Institute have been developing the device for more than 10 years.
The first of the four British patients was too sick to walk across Westaby’s office before getting the heart-assist device nearly two years ago. Now, he routinely walks 5 miles a day. The FDA has approved the Jarvik 2000 as a bridge to transplant in the United States, but not for permanent use as in Britain.
The two other living patients report that their quality of life has improved dramatically. All were in class IV heart failure, the highest stage for severity of the disease, in which all daily activities bring on discomfort. After receiving the pump, patients could perform up to moderate or heavy exertion before experiencing chest pain or breathlessness.
The fluid retention caused by a failing heart disappeared in all three patients, the researchers write. In fact, after three months, patients were able to stop taking diuretics, the drugs commonly given to heart-failure patients to help rid the body of excess fluid. Also during the first three months, echocardiography showed improvement in the patients’ left and right ventricle function.
The American Heart Association estimates that about 4.8 million Americans are living with congestive heart failure (CHF), which kills more than 50,000 people each year in this country. An estimated 60,000 to 70,000 of all heart failure patients are thought to be in class IV, says Frazier. Most class IV patients are unable to do simple activities such as ironing clothes or making a bed because their hearts cannot pump enough blood to meet even slight demands.
Frazier says only about 2,000 hearts are available for transplant each year. He estimates that half of all class IV patients, or some 30,000 patients, could benefit from the Jarvik 2000 left ventricular assist device (LVAD). Those would be patients in whom the left ventricle—the chamber of the heart that pumps blood out into the body—still works, but not well. The current study indicates that a patient’s own heart function improves after time on the pump.
“In most of these patients, all their hearts need is a boost,” he says. “That’s what the pump does. With the Jarvik 2000 taking over part of the work, the heart thinks it’s normal again. There has to be a synergy. It is not designed to totally take over or replace left ventricular function.”
The Jarvik 2000 is the smallest and simplest LVAD. It does not pulse, allowing for its miniaturization. Instead, the heart itself continues to beat and provide the pulse. The pump part of the device, which Frazier describes as thumb-sized, is small enough to fit inside the left ventricle, which reduces the likelihood of clotting problems. The tube-like outflow graft connects to the descending aorta behind the heart.
Co-authors include Adrian P. Banning, M.D.; Satoshi Saito, M.D., Ph.D.; David W. Pigott, F.R.C.A.; Xu Y. Jin, M.D., Ph.D.; Pedro A. Catarino, F.R.C.S.; Desiree Robson, R.N.; Narain Moorjani, F.R.C.S.; Atilla Kardos, M.D., Ph.D.; Philip A. Poole-Wilson, F.R.C.P.; and Robert Jarvik, M.D.
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