Going Under the Knife

Surgery's hidden risk.

5 min read

Aug. 4, 2000 -- Bad tickers ran in Joseph Calbreath's family, so at age 73 the retired Air Force pilot and hydraulics specialist opted for a stress test. One test led to another. His doctors told him he did indeed have a problem: a blockage in the coronary arteries supplying blood to his left ventricle, the main pump of his heart. They told him what he needed to fix it: heart bypass surgery.

But there's one thing they didn't tell him: Although his heart, if all went as planned, would work better after the operation, his brain might never work as well.

"He was never the same after that bypass," says his wife, Marian, of Novato, Calif. "For days afterward, he didn't even know where he was. Then, once we got home, I kept noticing strange things." Her husband would obsessively lock and relock doors. He forgot how to operate the controls of the RV. A few months after his operation, he was barreling over the Sierra Nevada mountains and suddenly downshifted into reverse, endangering them both.

Although surgical procedures like heart bypasses and hip replacements were once rare among the elderly, today they've become so commonplace that people over 65 make up more than a third of U.S. patients who go under the scalpel. Now a growing number of studies indicate that the older the patient and the more serious the surgery, the greater the risk that the person will leave the operating room with impaired concentration, memory, and other mental skills. While many have no choice but surgery to save their lives, the risk of mental impairment is significant enough that researchers say it should always be discussed with patients and their families. Unfortunately, too often doctors themselves are unaware of the risk or consider it too minor to mention.

"As we're operating on older and sicker patients, we've got to pay attention to the harm surgery might do to their quality of life," says Mark Newman, chief of cardiothoracic anesthesiology at Duke University and one of the field's key researchers. "Almost nothing is more devastating than losing mental abilities."

Studies now demonstrate that anywhere from 10% to 30% of elderly patients may suffer some cognitive decline after major surgery, although the severity varies widely. One cardiologist, for instance, discovered after his own heart bypass surgery that he was no longer able to match wits against a computer in chess games: He had lost the required ability to strategize three or four moves ahead. In rare cases, such as Calbreath's, the patient comes out of surgery so confused he can't lead a normal life.

While the damage often heals in a few weeks or months, it can linger for much longer. Using a battery of 10 tests, Newman and his colleagues at Duke assessed the mental performance of patients before coronary artery bypass graft surgery and at various times afterward. To their surprise, they discovered that of 313 patients, almost a third still showed cognitive deficits after five years.

Another of their studies on elderly bypass patients found that more than half had some diminished mental abilities when they were discharged from the hospital. That figure dropped to 24% after six months, but follow-up research indicates the decline persisted for years afterward.

Coronary bypass surgery -- now performed on about 650,000 U.S. patients a year -- seems to pose the greatest potential jeopardy to the brain. But other operations carry risk, too. Vascular surgery of any kind seems to heighten the likelihood of mental decline; so do abdominal and orthopedic surgeries.

One study of a thousand elderly patients undergoing abdominal and orthopedic surgical procedures found that three months later, 10% still experienced mental fuzziness that they didn't have before the operation. The study, headed by J. T. Moller, MD, at Copenhagen University Hospital, was published in the March 21, 1998, issue of Lancet.

Less invasive surgeries seem safer. "I wouldn't hesitate to tell patients to have those surgeries without fear," says Patricia Stockton, PhD, of Georgetown University Medical Center. Stockton studied mental decline in older patients undergoing cataract, prostate, and hernia surgeries. She found that only 1% experienced cognitive decline after the operations, according to her study, published in the winter 2000 issue of the American Journal of Geriatric Psychiatry. As more and more people live into their 80s and 90s -- often with the help of surgery -- researchers are starting to focus on two key questions: Exactly what is it about major surgery that triggers these brain malfunctions, and how can they be prevented?

Several studies have found that use of the heart-lung machine in bypass surgery raises a patient's risk of cognitive decline. The exact reason is unknown. However, fresh evidence published in the April 2000 issue of the Annals of Thoracic Surgery indicates that use of the machine may cause tiny emboli (fragments of cholesterol, clotted blood, or calcium in the vessels, for instance) to break loose during surgery and travel to the brain, causing lesions and other damage.

"Think of it like the rust that gets jarred loose when you clean pipes," says researcher Guy McKhann, director of the Zanxyl Krieger Mind Brain Institute at Johns Hopkins University. He notes that a new kind of brain scan, diffusion weighted imaging, can now pinpoint the brain damage and may aid in the development of drugs to protect the brain during surgery.

Heart-lung machines also cool the circulating blood several degrees during a bypass in order to protect other organs, a factor that seems to play a role as well. There may be an easy solution, however: Duke University researchers reported at the Society of Cardiovascular Anesthesiologists in May that when they warmed the blood more gradually after surgery, fewer patients suffered mental fuzziness.

As researchers piece together clues about how to make surgery safer, they advise physicians to fully discuss the risks with elderly patients. Joseph Calbreath, for one, never regained his mental acuity. Five years after his operation, he was diagnosed with Alzheimer's. But while Alzheimer's is characterized by gradual cognitive decline, his setback after surgery was abrupt and dramatic.

Today his wife Marian often wonders whether her husband would have agreed to the bypass had he known how it would forever change his life.

Says anesthesiologist Newman of Duke University: "Clearly we have some educating to do with physicians as well as patients."

Vicki Haddock is a reporter for The San Francisco Examiner and writes often about family and health issues. She lives in Petaluma, Calif.