Mechanical pumps originally designed to supplement the pumping action of a failing heart and keep the patient alive until a transplant could be found have taken a major step toward becoming a permanent treatment -- a development that could expand their use to tens of thousands of patients in the United States alone.
Results presented Tuesday at the Orlando, Fla., meeting of the American Heart Assn. showed that a new type of device more than doubled the two-year survival rate among heart failure patients. The key was the development of a smaller, quieter, more reliable pump that is less likely to break down and need replacement, an outcome that requires the patient to undergo a second major surgery.
The pumps are called left ventricular assist devices, or LVADs. They are not meant to replace the entire heart, only to assist in the pumping of the left ventricle, which pushes blood out through the aorta to the body.
Researchers originally thought that LVADs had to mimic the action of the heart, pushing out blood in a series of pulses that were timed to coincide with pulses from the heart itself. That required complex machinery to produce the pulses and sophisticated electronics to synchronize them with the heart.
Such devices had a high propensity to fail.
But more recently, researchers have concluded that a simple, continuously operating pump can work just as well, if not better. Such pumps typically have only one moving part -- the impeller -- and don't need to be synchronized with the heart, so their reliability is much greater. They are also much smaller, typically about one-seventh the size of older models.
The findings presented Tuesday involved one such device, manufactured by Thoratec Corp. of Pleasanton, Calif., and called the HeartMate II. The device is currently approved by the Food and Drug Administration only as a temporary bridge to a transplant.
"We had a sense that these smaller devices were going to have better long-term outcomes, and this trial proves it," Dr. Alfred A. Bove, president of the American College of Cardiology, said in an e-mailed statement. He was not involved in the research. "These devices have come a long way in five years. I expect that technology will continue to move things forward and they will be even better five years from now."
The need is great. About 150,000 Americans have advanced heart failure that could be treated with a transplant, but only about 2,100 donor hearts are available per year.
