Nov. 5 (HealthDay News) -- An implantable device that helps the heart pump blood -- and is about the size of a "D" battery, one-quarter the weight of the traditional device -- benefits women as well as men who are waiting for heart transplants.

That's the conclusion of new research that's expected to be presented Sunday at the American Heart Association annual meeting in Orlando, Fla.

"In the past, they were not as beneficial in women as in men, partly because of size," said Dr. Suzanne Steinbaum, director of Women and Heart Disease at Lenox Hill Hospital in New York City. "It didn't match up anatomically."

The new device in question, the HeartMate II, is an implantable left ventricular assist device that helps heart function in people with severe congestive heart failure. The U.S. Food and Drug Administration is currently reviewing an application to approve the pump-like device.

According to background information for the study, women with advanced heart failure tended to be underrepresented in studies of left ventricular assist devices (LVADs). Only 9 percent to 16 percent of participants in trials of the first generation of the device were women.

The new trial included 231 patients with heart failure, 23 percent of whom were women being treated at one of 40 different U.S. heart transplant centers and were awaiting heart transplants. The device serves as a "bridge" to transplantation.

The average age of the women was 56 (the range was 20 to 69 years). Men in the study averaged 54 years old, with an age range of 17 to 68.

Coronary artery disease was more likely to be the cause of heart failure in men -- 43 percent, compared with 31 percent in women.

The women may have suffered a weakened heart because of pregnancy, cancer chemotherapy, a viral infection or some other unknown cause, the researchers said.

Several study participants regained enough pumping power in the heart to have the device removed and no longer needed a transplant. And they've resumed normal physical activities, said the study authors, who are affiliated with such research centers as the Texas Heart Institute in Houston; the University of Rochester in New York; Johns Hopkins Hospital in Baltimore; Duke University, in Durham, N.C.; and Massachusetts General Hospital, in Boston.

Among the study's other findings:

• Six-month survival was about the same for men and women -- 80.6 percent versus 79.5 percent.
• The study found that 3.3 percent of women and 2.2 percent of men experienced strokes within two days of surgery; 13.6 percent of women and 4 percent of men experienced strokes after that.
• After three months with the device, 76 percent of women and 57 percent of men had increased the distance they could walk in six minutes by more than 200 meters. "Functionally, it helped women more than men," Steinbaum said.
• At the beginning of the study, all patients had Class IV heart failure, meaning they couldn't engage in any physical activity without discomfort. After three months with the device, 84 percent of women and men had only Class I and Class II heart failure symptoms -- no or slight limitations on physical activity. "Eighty-four percent of men and women went from Class IV heart failure -- they couldn't even move without being short of breath -- to Class I and II," Steinbaum said. "It's very exciting."

The trial was funded by Thoratec Corp. of Pleasanton, Calif., which manufactures the device. One of the study authors is the company's vice president for research and scientific affairs. The other study authors are consultants and serve on a Thoratec advisory board.

SOURCES: Suzanne Steinbaum, M.D., director, Women and Heart Disease, Lenox Hill Hospital, New York City; Nov. 4, 2007, presentation, American Heart Association annual meeting, Orlando, Fla.