"We're just trying to keep somebody alive."

With these words yesterday, Houston surgeon John Norman described the third attempt in medical history to save a dying patient by removing the main part of his heart and implanting an artificial heart.

A Houston surgical team led by Dr. Denton Cooley removed both of the lower pumping chambers of the heart of a man who had a coronary attack on the operating table, and sewed in a two-chambered plastic substitute.

Cooley ran afoul of the government with his Thursday operation, though, because he performed it without Food and Drug Administration approval. He cited "an emergency," but FDA officials said federal law and regulations require testing and approval of "new devices" before human use. Cooley "should have" obtained advance clearance, they said. But a hospital spokesman said "the patient's conditon was desperate -- no other alternative existed."

The Houston patient, identified as 36-year-old W. A. Mueffels, was in stable but poor condition yesterday. The Texas Heart Institute at Houston's St. Luke's Hospital, the operation site, issued a nationwide appeal for a donated human heart, preferably from an accident victim.

The artificial heart used in Texas is designed for short-term use while a patient awaits a heart transplant. The device has no power source, and its pumping chambers have to be operated by an external compressor and an air hose. p

Still, the new plastic heart -- and others like it under development at other medical centers -- includes "major advances" over old models, said Norman, a member of the St. Luke's research team.

A University of Utah team is now awaiting FDA approval to install a similar heart in a patient who would then, it is hoped, use it indefinitely, though it would mean living with a heavy cart to carry the power source.

The federal National Heart Lung and Blood Institute is spending $10 million a year on artificial-heart development, though many critics fear it could lead to a technology consuming many millions of dollars that might be used to help more people in some other way.

The eventual goal is a portable power source that a patient could wear on a belt.