Robert D. Karren, a former lineman for the NFL's San Francisco 49ers, is recovering from heart-transplant surgery at the University of Utah Hospital.

Karren, 47, was listed Monday morning in critical but stable condition following the surgery last Wednesday.He was diagnosed with ischemic cardiomyopathy early in 1984. Cardiologists determined that he'd had two previous "silent" heart attacks, which had permanently damaged his heart muscle.

Earlier, knee injuries had forced him to cut short his football career. During college, he played for Foothill College in Palo Alto, Calif., and was graduated from the Bay Area school in 1959.

In 1961-62, he played on the San Francisco 49ers' special teams and on offense.

Karren is a resident of Las Vegas.

He originally was treated by physicians at Stanford University Medical Center, where he was placed on a list to await a donor organ.

Physicians recommend he try the Salt Lake program, where they felt he may have a better chance of finding a heart large enough to accommodate his 6-foot-3, 210-pound frame.