[Paleopsych] Brain damage from bypass surgery
shovland at mindspring.com
Mon Sep 6 21:12:18 UTC 2004
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
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