Heart Surgery May Cause Cognitive DeclineJul 15, 2002 | Healthscout Heart bypass surgery, besides being stressful and potentially deadly, can temporarily dull a patient's mental edge.
That's the conclusion of a new study in which researchers examined people who had undergone bypass surgery, and found many suffered from short-term memory loss and had problems paying attention.
"The risk of cognitive impairment is fairly substantial," says study co-author Julian Keith, an associate professor of psychology at the University of North Carolina at Wilmington.
There is some good news. While the study didn't examine how long the mental problems persist, experts say they typically go away in a few weeks or months. "It tends not to be extremely severe," Keith says.
Doctors have performed heart bypass operations for more than 30 years, and they've noticed cognitive problems among patients from the start, Keith says.
However, researchers weren't sure how much of the mental decline starts before surgery even takes place.
From 1996 to 1999, Keith and his colleagues studied 39 heart bypass patients right before their surgeries and then three to four weeks afterward. All patients went to one surgeon in Wilmington, N.C.
The researchers also recruited 49 local senior citizens to serve as a control group, providing perspective about the cognitive skills of healthy senior citizens.
The study's findings appear in the July issue of Neuropsychology.
The researchers found the bypass patients' cognitive powers were lower than those of the healthy seniors both before and after their surgeries.
Doctors don't know why patients suffer from cognitive problems before surgery, but it could have something to do with stress or heart disease itself, Keith says.
"We're coming to appreciate more and more that cardiovascular disease shares a lot in common with the disease processes that lead to dementia and Alzheimer's disease ( news - web sites)," Keith says.
Bypass surgery may muddy mental skills because the process of hooking up a patient to a heart-lung machine can dislodge tiny blood clots and send them traveling to the brain, he says.
Large clots can cause strokes by cutting off circulation to parts of the brain. Small clots do less damage, but can clog tiny blood vessels called capillaries.
If surgery involving a heart-lung machine causes the release of tiny blood clots, it seems logical an operation without the machine would be better. However, doctors haven't found much improvement in post-surgery acuity when they've tried such operations, says Dr. Leland Housman, a cardiac surgeon at Scripps Mercy Hospital in San Diego.
"It doesn't seem to have helped as much as we've thought it would," he says. "Some people believe these changes in the brain may be due to any type of major surgery, as opposed to using the heart-lung machine in cardiac surgery."
Keith says the next step is to find ways to prevent cognitive problems through better understanding of the phenomenon. Even though they're usually minor, in rare cases the impairments can last for years and be quite severe.
"We want to send a message to our colleagues that the state of the art that has been accepted for several years is not good enough," he says.