SAN DIEGO, AUG. 27 -- In the first open-heart surgery on an ape, a medical team led by an internationally known heart surgeon worked for seven hours today to repair a life-threatening hole in the heart of a young orangutan at the San Diego Zoo.

A team of surgeons, nurses, anesthesiologists and medical technicians from the University of California San Diego Medical Center, assisted by veterinarians and animal keepers from the zoo, worked to patch a gaping hole in the heart of Karen, a 2-year-old Sumatran orangutan, an endangered species.

"If Karen were human, I'd tell her parents that everything went fine, and her prognosis is excellent," lead surgeon Stuart Jamieson said after emerging from the operating room at the zoo's hospital.

Without surgery to correct the congenital defect, the 22-pound orangutan faced the risk of a fatal heart attack. "It was either now or never for Karen," said Kurt Benirschke, professor of pathology at UCSD and founder of the zoo's Center for the Reproduction of Endangered Species.

The hole was a particularly large one, destroying nearly the entire wall between two chambers of the heart, preventing blood from getting enough oxygen. Jamieson and fellow surgeon Jolene Kriett stretched a section of the heart sac across the hole and stitched it shut.

Jamieson said the team encountered some anatomic differences in the skin and chest, but "once we were in the heart, it was like what we do every day."

If Karen recovers completely, she could grow to 80 pounds and live to age 30 or more. Keepers hope to have her back with other orangutans within a few weeks.

"I can't think of a better way to spend a Saturday than helping an endangered species survive," Jamieson said.