Smaller, simpler device can be used in more patients, expert says
WEDNESDAY, Aug. 29 (HealthDay News) -- A new kind of heart pump helped patients with heart failure so severe that their only option was a transplant, cardiologists report.
"The design is completely different from existing assist devices," said Dr. Leslie W. Miller, chief of cardiology at Washington Hospital Center, referring to the Heart Mate II that was implanted in 133 people with end-stage heart failure. "They are pulsatile, stimulating the function of the left ventricle, which injects blood into the bloodstream. This is a continuous flow device."
At six months, 75 percent of those with device were still alive, with a 12-month survival rate of 68 percent.
"The results were very positive," said Miller, lead author of a report on the trial in the Aug. 30 issue of the New England Journal of Medicine. "These patients were so sick that it was hard to get more than 75 percent survival at six months."
The device performed well mechanically, Miller said. And there was no increased incidence of blood clotting or similar problems when compared to older generations of such devices.
Data from the trial is being submitted to the U.S. Food and Drug Administration by Thoratec, the California company that plans to market the device and funded the trial. An FDA expert panel will consider whether the agency will approve the device as a bridge to heart transplants.
Another study of the device as a permanent implant for people with less severe heart failure has just been completed, and that data will also be submitted to the FDA, Miller said.
The device "looks like a flashlight," he said. "It weighs about 14 grams, and is about a fifth the size of existing devices. It is also silent in operation."
That small size "will open the door for use in more patients," said Dr. Kenneth L. Baughman, a professor of medicine and cardiology at Brigham and Women's Hospital in Boston and co-author of an accompanying editorial. "It can be used for support in women and younger adults."
The continuous flow pump "offers a different kind of support," he said. "It is smaller in size with fewer moving parts."
In fact, the device has just one moving part, the rotor that transports blood, Miller said.
The new pump does not do away with the problems that have accompanied older devices, Baughman said. "There still are problems such as thromboembolisms [clots], bleeding and infection," he said. "These are not eliminated, but they do not occur at higher levels than with current devices."
The continuous flow pump does present one difficulty -- determining blood pressure, Baughman said. Because of the way the device works, it does not provide the systolic and diastolic blood pressure reading that are a constant in heart monitoring.
"And what is not known is what happens to the body over time," when a continuous flow pump is implanted, Baughman said. "We'll just have to wait and see how it works out over time."
The workings of the current generation of assist devices are described by the American Heart Association.
SOURCES: Leslie W. Miller, M.D., chief, cardiology, Washington Hospital Center, Washington, D.C.; Kenneth L. Baughman, M.D., professor, medicine and cardiology, Brigham and Women's Hospital, Boston; Aug. 30, 2007, New England Journal of Medicine
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