This month, as the patient lay anesthetized on a table, a cardiologist made a half-inch incision through the skin of his chest. She removed a small implanted heart monitor with failing batteries and inserted a new one.

The patient, like many older males, had been diagnosed with cardiac disease; the monitor would provide continuing data on heart rate and rhythm, alerting his doctors to irregularities.

Closing the incision required four neat stitches. In a few hours, the patient, a gorilla named Winston, would rejoin his family in their habitat at the San Diego Zoo Safari Park.

“Winston, at 51, is a very old male gorilla,” said Dr. Matt Kinney, a senior veterinarian at the San Diego Zoo Wildlife Alliance who led the medical team through the procedure. With improved health care, new technology and better nutrition, “we see animals living longer, and they’re healthier for longer, too,” he said.

In “human-managed care” (the term “in captivity” doesn’t fly at zoos anymore), gorillas may live two decades beyond the 30- to 40-year life spans that are common in the wild, and longer than zoo gorillas did in decades past.

As with their human relatives, however, aging also brings chronic illnesses that require testing, diagnosis and treatment. Gorillas are prone to heart disease, the leading cause of death for them as for us.