Fixing The Heart, Hurting The Brain
Many patients who undergo heart bypass surgery suffer a significant and, it turns out, long-lasting loss of brain power, a study suggests.
Doctors have known that people often lose some of their mental sharpness immediately after a heart operation, but many seemed to recover fairly quickly. The new study, however, found that this recovery is short-lived.
The study looked at 261 patients who were on a heart-lung machine during bypass surgery. It found that five years after the operation, 40 percent showed a 20 percent drop in mental ability. That loss is similar to what a person normally goes through between the ages of 40 and 60.
Doctors do not know for sure why this mental loss happens, or even whether the operation causes it. For example, it might be that people whose arteries need to be replaced already have damaged blood vessels in their brains as well. The loss might also have something to do with being put on a heart-lung machine, which circulates blood through the patient's body during surgery.
An estimated 400,000 people a year are put on heart-lung machines for a bypass operation in the United States. The findings suggest that 160,000 of them risk losing some of their mental ability.
Dr. Mark F. Newman, who led the study published in Thursday's New England Journal of Medicine, noted that many patients in the Duke University study might not have lived five years without the operation.
"Now it's a matter of fine-tuning" the operation "to improve the quality of life as well as the length of life," he said.
Moreover, the people who lost mental ground in this study might have lost brain power faster anyway, said Dr. Irving L. Kron, chief of cardiac and thoracic surgery at the University of Virginia School of Medicine.
"It may be that the stress of the operation brings things out or pushes things along that were there to start with," Kron said.
Newman said other research appears to indicate that there are fewer problems with the brain after bypass operations done without the heart-lung machine.
Participants in the latest study took tests in memory, attention, concentration and manual dexterity five times: before the operation, when they left the hospital, and six weeks, six months and five years later.
Fifty-six percent did significantly worse when they were released from the hospital than when they were admitted.
Nearly half of those people were back up to pre-operation levels when tested six months after the operation. But at the five-year mark, most were back down to the levels measured when they were leaving the hospital.
Older people and those with the least education were the most likely to have lower scores five years later.
People who did not show any losses just after the operation were in equally good shape five years later
The bypass operations took place from 1989 through 1993, and the last five-year tests were given in 1998.
Doctors are more aware of problems which can cause brain damage than they were when those bypasses were done, and improved techniques "will reduce or have reduced neurocognitive dysfunction," Newman said.
"I think our technology is continuing to improve," he said.
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