AbioCor latest innovation in crowded field
By From Rhonda Rowland
(CNN) -- For most people, the term "artificial heart" brings to mind images of Barney Clark, who received an early model called the Jarvik 7 in the 1980s. But researchers say the technology has progressed tremendously since then, and today's AbioCor represents a major shift.
"The original Jarvik 7 was a very primitive device compared to today's standards," said Dr. Mehmet Oz, a cardiologist at Columbia University who could be implanting one of the new devices.
"The technology just didn't exist yet. It was a noble experiment, but when it failed it actually held the field back. The AbioCor device learned from the lessons of the original Jarvik 7."
The Jarvik 7 was a cumbersome device. Although part of it was implanted in Clark's body, he was tethered to a large machine and could not move freely. He died 112 days after the implant from multiple strokes and infections caused by the device. Other recipients of this artificial heart fared similarly.
"There was an awful lot of hype and a lot of attention to those first implants, as if these were breakthrough devices that were going to be the answer for heart disease," said Dr. Patrick McCarthy of the Cleveland Clinic.
"As time went on, we learned much more about the complications of the device as very sophisticated machines, very difficult to implant and keep people going and a very limited quality of life. So, in the long run, they turned out to be very unsuccessful."
The new artificial heart is made primarily from titanium and plastic. Since the device is completely implanted, patients would be able to move freely. And because patients are not pierced with tubes and wires, researchers say chances of infection should be reduced.
Following the experience with the Jarvik 7, researchers turned their attention away from replacement hearts to so-called assist devices designed to help the ailing heart or give it a rest.
"You usually don't have to cut out someone's heart" and replace it, said McCarthy, "instead, you can use these booster pumps or the ventricular assist devices. So, it's a much less radical operation."
In the vast majority of patients, the main pumping chamber, or left ventricle, is the problem. So-called left ventricular assist devices (LVADs) take over the work of the left ventricle while the heart is left in place. These LVADs are often used as a bridge to a heart transplant. Patients are tethered to battery packs but often can live at home and resume normal activities. In some patients, the heart's function spontaneously improves while on the LVAD, eventually allowing them to be taken off the heart transplant waiting list.
"They're clearly going to be the future and we think we're on the breaking point where you'll see them much more commonly, like you see pacemakers today," said McCarthy.
Researchers are experimenting with a new generation of LVADs that are much smaller and hope they can permanently assist the heart so a transplant can be avoided altogether. The newer pumps weigh about four ounces compared to the older generation devices, which weigh about five pounds.
"There's no question that these will be where cardiac medicine is heading," said McCarthy, "that we will start to use these pumps permanently and that the quality of life will be at a point where it will be as good as a heart transplant and hopefully better than a heart transplant, because you don't have to take all those medications and you don't have rejection."
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