ASHEBORO--A 35-year-old female chimpanzee died Thursday morning at the North Carolina Zoo while under treatment for heart problems.

Betty was one of the oldest animals in the zoo's chimpanzee troop, which includes 12 other members to rank as one of the largest chimp collections in U.S. zoos. According to Curator of Mammals Terry Webb, Betty was found to be lethargic, trembling and nauseated when keepers arrived around 7 a.m.

Zoo veterinarians were called in immediately and transferred the chimp to the park's Hanes Veterinary Medical Center where she was placed under anesthesia to determine the cause of the problem. Zoo Chief Veterinarian Dr. Mike Loomis said the chimp went into cardiac arrest while on the examination table.

The veterinary staff was able to use CPR to restart the chimp's heart twice, but after a third cardiac failure the animal died. A necropsy, or animal autopsy, performed Thursday afternoon revealed the chimp had suffered from thrombosis or blood clots in the pulmonary veins, Loomis said. Further tests on tissue and other samples will be conducted by an outside laboratory but it could take several weeks to get the results, Loomis added.

Betty was transferred from Busch Gardens in Tampa, Fla., to the N.C. Zoo in September 1979. She gave birth to a female offspring, Amy, in December 1983. Amy remains at the N.C. Zoo and along with the other members of the chimpanzee troop showed no signs of illness Thursday.

The zoo is an agency of the N.C. Department of Environment, Health and Natural Resources, Dee A. Freeman, Secretary; Beverly E. Perdue, Governor.