Fully Internal Heart Device Installed
Surgeons in Louisville, Ky., placed an artificial heart in a patient’s chest Monday--the first fully self-contained artificial heart to be implanted in a human being.
The patient, who was not identified by either name or gender, was believed by doctors to be within a month of death at the time of the operation and is not expected to survive more than a few weeks with the new titanium-and-plastic heart, which remains an experimental device.
But many cardiologists nonetheless expressed cautious optimism at the news, which they saw as renewed encouragement for efforts to fit heart failure patients with off-the-shelf artificial organs, thus alleviating the severe shortage of hearts available for transplants.
The operation comes at a time when surgeons and device manufacturers, after a period of discouragement, once again have been developing devices to replace or assist ailing hearts.
“It’s exciting,” said Dr. Timothy Gardner, chief of cardiothoracic surgery at the University of Pennsylvania Medical Center in Philadelphia and a spokesman for the American Heart Assn. “There’s a tremendous need for such a device. . . . It’s been the goal of many surgeons and developers since way back.”
The heart--called AbioCor--was developed by Abiomed Inc., based in Danvers, Mass., in collaboration with the government’s National Heart, Lung and Blood Institute. Earlier this year, the federal government gave approval to five hospitals, including UCLA Medical Center, to implant the experimental device into patients. Monday’s operation, at Jewish Hospital in Louisville, was the first such test.
The hospital released no information on the patient, the operation or how it was paid for, beyond saying that the patient was resting comfortably and that a briefing would be scheduled for today.
Doctors cautioned that this first human implant is a very preliminary step and just one of several experiments planned at various sites. The initial goal is to see whether AbioCor can extend life--with acceptable quality--for people who have less than 30 days to live and no other medical options.
“A lot will be learned from this initial experience,” said John Watson, director of the clinical and molecular medicine program at the National Heart, Lung and Blood Institute.
The device used is far less cumbersome than earlier experimental artificial hearts, consisting of a two-pound, two-chambered replacement heart that is implanted in the chest after the real heart is removed. A rechargeable battery and electronics are implanted elsewhere in the body.
No wires protrude from the body, cutting down on the instrusiveness of the device and reducing the risk of infection. Instead, the internal battery is recharged through the skin using a battery pack worn outside the body on a belt. A quiet, internal pump simulates the rhythm of a heartbeat and can alter its effort according to the patient’s level of exertion, says the manufacturer.
Acute Need for Artificial Hearts
The need for artificial devices to replace, or at least to supplement, the heart is great, cardiologists say. As many as 700,000 Americans are diagnosed with heart failure each year. Heart failure contributes to about 250,000 deaths a year, according to the National Institutes of Health. Anually, only 2,000 hearts are available for transplanting, and about 4,000 patients are on transplant waiting lists.
“There’s a great mismatch in terms of what’s available and what’s needed,” said Dr. Jon Kobashigawa, medical director of the heart transplant program at UCLA.
What’s more, he said, those who get transplants must take powerful drugs to prevent their immune systems from rejecting their new hearts, and such drugs can have serious side effects. An artificial heart could circumvent this need and potentially improve the quality of life of heart failure patients.
Before Monday’s operation, the AbioCor heart had been transplanted into calves for 12 weeks and performed well, Watson said. A number of AbioCor hearts have also been pumping nonstop outside bodies without a problem for more than a year--which is a record for a device so complex, he said.
However, Watson and others cautioned, these test situations are a far cry from the conditions in a human body, and it is impossible to predict how the artificial heart will hold up. There are many problems that such artificial devices can have, and they have posed challenges since the inception of efforts to build artificial hearts.
Blood, for instance, tends to clot when exposed to non-biological surfaces. That can lead to strokes and heart attacks and requires the patient to take blood thinners. Thinners, in turn, can cause excessive bleeding.
Infection is another challenge, especially if any parts of the device protrude from the body. And if devices are too rough, blood cells can burst, leading to anemia.
Efforts to develop an artificial heart reach back decades, and early efforts were discouraging. In 1982, surgeons at the University of Utah implanted an artificial heart known as the Jarvik-7 in several people.
The best known recipient of that device, Barney Clark, died of a series of strokes 112 days later. His quality of his life in the meantime was poor, recall cardiologists. The pump, situated outside his body, was very noisy, and he had tubes running into his body.
“I remember seeing Barney Clark on the front page of the newspaper--hooked up to a console as high as the ceiling with tubes coming out of the console going into his chest. I remember saying to myself: ‘That’s no way to live a life,’ ” recalled Kobashigawa.
Experts say that this early experience was demoralizing, and researchers scaled back their efforts. They focused not on full replacement hearts, but on such things as so-called left ventricular assist devices, less ambitious equipment to help people with heart failure. Today, a variety of these assist devices are in use or being studied in clinical trials. Some have protruding parts, but more recent models do not.
Unlike the AbioCor heart, left ventricular assist devices help only the left chamber of the heart--the one responsible for pumping blood around the body and the one that most often fails. When a left ventricular assist device is used, the right chamber, which pumps blood to the lungs, must continue to function on its own.
Development of Assist Devices
Assist devices were viewed initially as bridges--ways to keep patients alive until they could get heart transplants. However, clinicians have since found that the devices allow the hearts of some patients to recover sufficiently so that the device can later be removed. (Implanting an assist device does not entail removing the heart.)
Clinical trials are underway to see if assist devices can be used as permanent solutions for some patients, instead of simply bridges to transplants.
Some heart doctors, including Robert Jarvik, who invented the Jarvik-7 and has since developed an assist device, wonder if such devices, with their increased sophistication, have largely supplanted the need for a total artificial heart. Others counter that the need is still great.
“There are patients who do not respond to medications or to left ventricular assist devices,” said Dr. James Willerson, medical director of the Texas Heart Institute (where the AbioCor heart is also to be tested) and president of the University of Texas Health Science Center, both in Houston.
“But until one sees this device operating in a number of patients for some period of time, we’re not going to know all the possible side effects as well as the benefits.”
(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)
Battery-Powered Heart
Just like a human heart, the artificial heart consists of two pumps.
*
One pump receives oxygen-depleted blood and sends it to the lungs.
*
Another pump receives oxygen-rich blood and sends it to the rest of the body.
*
* Capacity: The heart can
deliver more than two gallons of blood every minute.
* Size: About two pounds and the size of a grapefruit
* Cost: $70,000 per device
Sources: Abiomed Inc.; Times staff reports
(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)
A New Lifeline
The artificial heart implanted in a patient Monday is an AbioCor implantable replacement heart designed to closely mimic the function of the human hearts. How it works:
*
Artificial heart: Titanium with two plastic pumps to simulate the functioning of a real heart. Weighs about 2 pounds.
Wireless energy transfer system: Transfers energy from external battery to power heart; recharges internal battery.
External battery pack: Lithium battery weighs 4 pounds, is main power source.
Rechargeable internal battery: Controls heart pumping when external battery is unavailable, such as during a shower.
Controller: Monitors pump to meet blood flow demand. Transmits data to external system.
*
Sources: Abiomed Inc., Times staff reports
