Hearts and Minds

By Christine Gorman

For 15 years David Rasmussen, 72, a retired airline dispatcher living in Clarksville, Va., had solved at least one crossword puzzle a day. But for a while after he underwent double-bypass surgery at Duke University Medical Center last October, Rasmussen hardly glanced at his beloved crosswords. "I found it hard to concentrate," Rasmussen recalls. "All I wanted to do was sit around and watch television."

You could hardly blame him. After all, Rasmussen had had his chest cracked open, his heart stitched up and was swimming in painkillers. Is it any wonder that he--and 30% to 80% of the more than 500,000 Americans who undergo bypass each year--would experience bouts of mental fogginess after surgery? Most surgeons assumed these effects were temporary, since they usually disappeared a few weeks or months after the operation--as they did in Rasmussen's case. Besides, doctors tended to focus on the more pressing bypass complications--stroke, for example, which occurs in 1% to 5% of cases and can lead to permanent disability or death.

But there has always been a nagging suspicion that the subtle changes in personality and lapses in mental acuity that are sometimes seen after bypass surgery might be the result of brain damage caused by the operation itself. That's why there was so much interest last week in a study published in the New England Journal of Medicine that found 42% of bypass patients still experienced cognitive decline five years later.

The study, conducted by Dr. Mark Newman and colleagues at Duke University Medical Center, tracked 261 patients and periodically gave them standardized tests of cognitive function. Many recovered fully in the weeks after surgery, but about a third did not. In general, patients who were older, less well educated or who had previously experienced mental confusion in the aftermath of the surgery appeared to be at greatest risk of a long-term decline. (Vice President Dick Cheney was 47 when he underwent quadruple-bypass surgery in 1988.) What surprised Newman's team most, however, was that the rate of impairment, after falling to 24% in the first six months, subsequently rose, suggesting that the apparent damage in many cases was permanent.

Before anyone decides to put off a potentially lifesaving operation on the basis of these findings, there are a few points to bear in mind. The tests used to measure cognitive ability are very sensitive. Any one of us could "fail" such an exam and still not notice a great difference in our daily life. In addition, this is a preliminary study that lacked a control or comparison group. "I think there's something to this," says Dr. Patrick McCarthy, a cardiac surgeon at the Cleveland Clinic. But he is quick to add that it's not at all clear how much of the decline is due to the bypass and how much to aging.

It's also possible that the surgery doesn't cause mental dysfunction so much as unmask it, in the way that a stress test can reveal an underlying heart condition. After all, if the arteries are clogged, there's a good chance that at least a few blood vessels in your head are having trouble getting oxygen to your brain. Confusion and memory problems can also be a sign of depression, which has its own causes and treatments.

Still, it's not difficult to imagine how a bypass operation could cause brain damage. During most procedures, the heart is actually stopped for as long as two hours while a heart-lung machine takes over the job of oxygenating the blood and pumping it through the body. Studies have shown that microscopic bubbles of air or tiny bits of fat and plaque are often loosed into the bloodstream in the process. Even if they are too small to trigger a full-scale stroke, they may cause minor damage in the cerebral tissue.

Doctors are already exploring ways to make bypass operations easier on the brain. Some surgeons, for example, try to minimize the risk of shaking loose a clot by scanning the aorta with ultrasound for plaque-free regions at which to attach the heart-lung machine. Another option being tested in the U.S. is to stick a filter into the aorta to catch any wayward debris.

Most ambitious of all is a new type of bypass procedure that allows surgeons to operate directly on a beating heart without having to resort to a heart-lung machine. Such off-pump surgery requires great technical skill, however, and isn't an option for everyone. (The best candidates have stable heart function and discrete, easily accessible blockages.) Still unknown is whether off-pump grafts last as long as conventional ones or even if the operation makes any real difference to the brain.

The New England Journal study has highlighted one of the drawbacks of bypass operations, but even its authors say that they hope it doesn't scare anybody away from getting necessary surgery. They note that many of the study participants wouldn't have lived five years without the operation. To them, a little trouble with memory or attention might seem worth it.

It certainly does to David Rasmussen. Four months after his operation, he's glad to be alive and happy to feel as sharp as he does. "I'm back to working the New York Times crossword," he says. "I think I got the better part of the bargain."