[Paleopsych] Brain damage from bypass surgery

[Steve]

http://www.findarticles.com/p/articles/mi_m0815/is_2001_March/ai_71198910
The memory loss and other cognitive problems long known to result from 
coronary-artery bypass surgery are often minimized by heart surgeons as 
merely transient problems. Mark F. Newman, MD and colleagues at Duke 
University Medical Center, however, have conducted the first study to show 
that for a substantial minority who undergo this operation, mental 
impairment will recur years later. Their findings were published last month 
in The New England Journal of Medicine (2/8/01).
The 261 study participants were given mental tests before undergoing bypass 
surgery at Duke between 1989 and 1993. Their average age was 60 years at 
the time of surgery, and most were men. All were tested again at discharge 
from the hospital, at six weeks, six months, and five years. The incidence 
of cognitive decline was 53% at discharge, 36% at six weeks, 24% at six 
months, and 42% at five years. Their problems ranged from concentration   
difficulties to stroke. The people showing cognitive deficits at discharge 
were also the people most likely to have the problem at five years.
"Long-term cognitive changes after [bypass surgery] have received less 
attention, despite common reports by patients that they are 'just not the 
same' after surgery," wrote Ola A. Selnes, PhD, and Guy M. McKhann, MD in 
an editorial that accompanied the study. They describe the changes as 
subtle, involving problems following directions, mental arithmetic, and 
planning complex actions. They note that there is still much to be learned 
about the mechanisms of late cognitive decline after bypass surgery.
The suspected route of brain damage is the heart-lung machine. During 
surgery, the patients blood is circulated through this machine picking up 
air bubbles along the way. The bubbles may block the blood flow through the 
tiny vessels of the cranium, killing brain cells. According to another 
theory, tiny fragments of diseased aorta dislodged during surgery are 
circulated through the heart-lung machine, migrating to the brain, blocking 
blood flow, and causing strokes.
Dr. Newman and colleagues acknowledged the weaknesses of their study. For 
example, all elderly people tend to show cognitive deficits with age; and 
their study lacked participants who did not undergo bypass surgery for 
comparison purposes. Still, the cognitive decline that normally occurs with 
aging is gradual, and the investigators say that their findings show that 
bypass surgery is an additional factor.
More than 500,000 coronary-artery bypass operations are performed yearly in 
the U.S. Though there has been substantial drop in the death rate due to 
improvements in surgical and anesthetic techniques, according to the Duke 
investigators, the incidence of cognitive decline has changed little over 
the past 15 years.
COPYRIGHT 2001 Center for Medical Consumers, Inc.
COPYRIGHT 2001 Gale Group