A U.S. Food and Drug Administration panel on Wednesday backed an artificial heart to keep the sickest patients alive while they wait for a transplant.

The CardioWest Total Artificial Heart by SynCardia Systems would be the first on the market if the FDA follows the panel’s 10-1 recommendation. The agency usually agrees with the advice of its expert panels.

The FDA advisers said the CardioWest replacement heart successfully kept patients alive, but should only be used in dire situations because of a high rate of side effects like infection, seizure, stroke and bleeding.

“This is not something any of us would subject ourselves to unless we were dying,” said panelist Judah Weinberger of Columbia University. But, he added, “I think this likely has net benefit to the patient.”

Privately held SynCardia is seeking approval to use the device as a temporary fix before transplants for heart failure patients with less than 30 days to live. Because it requires a large computerized console to regulate blood flow, it can only be used in hospitals.

Five million Americans have failing hearts, and 100,000 are sick enough for a transplant. Only about 2,100 of the 3,800 on the waiting list in 2002 received transplants. Up to a quarter of the patients on the list die while waiting.

Mechanical pumps called left ventricular assist devices can take over, but often can’t maintain full heart function, and 30-40 percent of patients on the devices die before transplant.

The CardioWest heart takes over completely, and is better at maintaining blood pressure and supplying oxygen to organs, said Dr. Marvin Slepian, president and chief executive officer of Tucson, Arizona-based SynCardia.

The committee debated who should get the devices, but most agreed it should be people facing imminent death and who wouldn’t benefit from the left assist devices.

Slepian estimated that several hundred patients per year would receive the device.

The device’s huge costs, $80,000-$100,000 for the heart, plus hospital and surgery expenses, aren’t currently covered by insurance. FDA approval should bring some coverage, Slepian predicted.

Another company, Abiomed Inc., hopes to win FDA approval of its artificial heart called AbioCor by the second half of 2004. Unlike SynCardia’s device, the AbioCor is completely implanted.