Doctors in England have implanted into the chest of a 61-year-old man the first permanent electronically powered device that can take over the pumping functions of an ailing heart.
In this case, the electronic implant, about the size of a thumb, has rescued the patient from the brink of death. He had been given only weeks to live.
The electronic implant is an example of how the increasing miniaturization of medical devices can handle huge physiological tasks.
Called a Jarvik 2000 heart, the device is a new type of left-ventricular assist device, intended as a long-term solution to end-stage heart failure. The surgery in England is born of the revolutionary idea that devices with more complicated cardiac tasks than pacemakers can be permanently implanted.
"There is now great enthusiasm for a mecha nical solution to heart failure," said Stephen Westaby of John Radcliffe Hospital in Oxford, England. He led the surgical team that implanted the electronic device. "The Jarvik 2000 heart has important advantages over other devices, and we are impressed with its performance in our early clinical experience."
A left-ventricular assist device, or LVAD, is implanted through a minimally invasive
incision on the left side of the chest and is fitted into the heart's left ventricle. This device, according to preliminary results of clinical trials in this country and Britain, has helped reduce the size of failing hearts and assists them into efficiently pumping blood.
Guide wires run from the device through the chest and up the neck and connect to a tiny power source behind the ear. The i mplanted pump is non-pulsitile, meaning it does not beat. Its internal mechanisms spin at 12,000 rpm, aiding the heart's contractile activity.
The heart, miraculously, continues its rhythm, which improves over time, because the LVAD has taken over much of the pumping function.
There are few solutions, doctors say, to heart failure, known more formally as congestive heart failure. It affects 5 million people in this country. Congestive heart failure is typified by an enlarged heart that pumps inefficiently. Patients don't receive enough oxygen.
For example, in people with normal hearts, the organ at rest pumps about 5 liters of blood per minute. At best for those with congestive heart failure, the heart can manage to pump only 3 liters Transplantation is a solution for some patient s, mostly those under 60. For older people -- and congestive heart failure usually strikes those in their 60s and beyond -- transplantation usually is not performed.
As populations age, doctors say, cases of congestive heart failure are expected to rise, and solutions will be needed.
Dr. Bud Frazier, chief of cardiopulmonary transplantation at the famed Texas Heart Institute in Houston, is t esting the new device in clinical trials and said, "This is something that will be of help to a large number of patients."
The Jarvik 2000 is the latest in a long succession of pumps from the inventor, Dr. Robert K. Jarvik, who helped make history in 1981, when the first Jarvik heart was implanted into the chest of Barney Clark at the University of Utah Medical Center. Jarvik heads Jarvik Hea rt Inc. in Manhattan. His early devices required large briefcase-size power packs to be trudged around.
But there were significant problems, and not just with the inconveniently sized power pack. There were problems with infection and too much noise from the devices.
Now they know the entire organ need not be artificial and that LVADs take up less space and provide more pumping power. Frazie r said the only way to tell the Jarvik 2000 is electronically powering a patient's heart is to listen closely through a stethoscope.
At the Texas Heart Institute, the Jarvik 2000 has been used since April in three operations. There, the device is not being used as a permanent implant but as a bridge to transplant.
Westaby and his team implanted the device in June but did not publicize details about it until Sept. 9 in The Lancet, a British medical journal.
The patient, Peter Houghton, a hospital psychotherapist, had been given only weeks to live and had been deemed too old and too sick to undergo a heart transplant. His doctors entered him into a clinical trial that is part of an artificial heart program and implanted the device.
Within six weeks, according to the study, exercise tolerance and heart and kidney function improved; symptoms of heart failure resolved significantly. Recently - surprisingly - Houghton resumed an activity he had abandoned years ago because of his failing heart: He went hiking.
Distributed by the Los Angeles Times-Washington Post News Service
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