Johnny Stephens
Well-known member
Apologies if this has been posted before:
http://www.principalhealthnews.com/article/hscoutn/103406282
TUESDAY, Feb. 11 (HealthScoutNews) -- Heart bypass patients often suffer a
decline in mental skills after their surgery.
Now, Duke University researchers think they may know why.
Bacteria from the intestines released into the bloodstream during the
surgery causes inflammation of the brain, the researchers say.
When surgeons operate on a stopped heart during a bypass operation, a
heart-lung machine circulates blood throughout the body, resulting in less
blood flow to the intestines, the researchers say in a study in the February
issue of Stroke .
The reduced blood flow weakens a blood barrier in the lining of the large
intestine, letting bacteria enter the bloodstream. This, in turn, causes
inflammation of the brain in patients with lowered immune response to the
bacteria, the researchers say.
Elderly patients seem particularly vulnerable because of lower immune
response to endotoxins -- part of bacteria -- including those present in the
intestinal tract, the study found.
The Duke team followed 343 patients who had elective bypass surgery,
formally known as coronary artery bypass grafting, in which a blood vessel
from another part of the body is used to reroute blood around a blocked
artery leading to the heart.
Before surgery, researchers measured antibodies to the endotoxins in the
patients and gave them cognitive tests measuring abilities such as
short-term memory, attention, concentration and language comprehension.
Thirty-six percent of the patients suffered a decline in mental abilities,
based on tests six weeks after surgery. Patients over 64 who had low
immunity to endotoxins faced nearly twice the risk of cognitive decline
after surgery, says Dr. Joseph P. Mathew, the study's principal
investigator.
"Even though they recover from the physical symptoms, if we leave them with
mental difficulties or memory problems, we haven't really cured the
problem," says Mathew, a cardiac anesthesiologist at Duke. "We've given them
a different problem, and that's the rationale for trying to address this
problem."
Mathew says efforts to improve immunity to endotoxins might reduce the
decline in mental ability among older patients. Duke researchers, for
example, plan a trial in which they will give "antagonists" designed to
block the effects of endotoxins before surgery. Vaccines may be another
option, he says.
"We need to address the issue of cognitive decline because we are
successfully operating on a progressively older and sicker group of
patients," Mathew says. "While many of the complications of cardiac surgery
have been minimized, cognitive decline is still one of the main areas where
continued research can improve the quality of life for these patients."
Duke researchers reported in 2001 that many heart bypass patients who were
on a heart-lung machine had suffered a loss of mental ability. Six months
after bypass surgery, 24 percent had suffered declines in mental ability;
after five years, 42 percent had, the 2001 study found.
However, that study did not determine why, and Mathew says the latest
research was designed to provide some answers.
Dr. Timothy Gardner, a professor of heart surgery at the University of
Pennsylvania, says the new study could shed light on the body's possible
responses to heart-lung machine use.
However, Gardner, who is also a spokesman for the American Heart
Association, says the study's findings do not prove bypass surgery leads to
a long-term decline in mental ability.
"I'd put this study in the category of interesting, but preliminary,"
Gardner says. "It's interesting because they've explained a pathological
condition that seems to occur, but I don't think this study, in particular,
is important to proving that heart surgery is dangerous to the brain."
He points out that the study looked at patients' mental ability just six
weeks after the operation, and did not assess whether they would recover
later.
Patients, Gardner says, frequently suffer depression or confusion after
surgery. And, he adds, the study failed to answer whether higher levels of
endotoxins in the bloodstream are common only in heart surgery or also other
major operations, such as removal of a tumor.
Gardner cites research presented last month by a team from Johns Hopkins
University that looked at bypass patients and a control group of heart
disease patients that did not have surgery. The Hopkins researchers found
that whether the patients had surgery had no bearing on changes in mental
ability measured a year later.
Most bypass surgery is performed on a stopped heart while a heart-lung
machine keeps the patient alive, the American Heart Association says.
However, the number of procedures performed without a pump, while the heart
is beating, is increasing.
http://www.principalhealthnews.com/article/hscoutn/103406282
TUESDAY, Feb. 11 (HealthScoutNews) -- Heart bypass patients often suffer a
decline in mental skills after their surgery.
Now, Duke University researchers think they may know why.
Bacteria from the intestines released into the bloodstream during the
surgery causes inflammation of the brain, the researchers say.
When surgeons operate on a stopped heart during a bypass operation, a
heart-lung machine circulates blood throughout the body, resulting in less
blood flow to the intestines, the researchers say in a study in the February
issue of Stroke .
The reduced blood flow weakens a blood barrier in the lining of the large
intestine, letting bacteria enter the bloodstream. This, in turn, causes
inflammation of the brain in patients with lowered immune response to the
bacteria, the researchers say.
Elderly patients seem particularly vulnerable because of lower immune
response to endotoxins -- part of bacteria -- including those present in the
intestinal tract, the study found.
The Duke team followed 343 patients who had elective bypass surgery,
formally known as coronary artery bypass grafting, in which a blood vessel
from another part of the body is used to reroute blood around a blocked
artery leading to the heart.
Before surgery, researchers measured antibodies to the endotoxins in the
patients and gave them cognitive tests measuring abilities such as
short-term memory, attention, concentration and language comprehension.
Thirty-six percent of the patients suffered a decline in mental abilities,
based on tests six weeks after surgery. Patients over 64 who had low
immunity to endotoxins faced nearly twice the risk of cognitive decline
after surgery, says Dr. Joseph P. Mathew, the study's principal
investigator.
"Even though they recover from the physical symptoms, if we leave them with
mental difficulties or memory problems, we haven't really cured the
problem," says Mathew, a cardiac anesthesiologist at Duke. "We've given them
a different problem, and that's the rationale for trying to address this
problem."
Mathew says efforts to improve immunity to endotoxins might reduce the
decline in mental ability among older patients. Duke researchers, for
example, plan a trial in which they will give "antagonists" designed to
block the effects of endotoxins before surgery. Vaccines may be another
option, he says.
"We need to address the issue of cognitive decline because we are
successfully operating on a progressively older and sicker group of
patients," Mathew says. "While many of the complications of cardiac surgery
have been minimized, cognitive decline is still one of the main areas where
continued research can improve the quality of life for these patients."
Duke researchers reported in 2001 that many heart bypass patients who were
on a heart-lung machine had suffered a loss of mental ability. Six months
after bypass surgery, 24 percent had suffered declines in mental ability;
after five years, 42 percent had, the 2001 study found.
However, that study did not determine why, and Mathew says the latest
research was designed to provide some answers.
Dr. Timothy Gardner, a professor of heart surgery at the University of
Pennsylvania, says the new study could shed light on the body's possible
responses to heart-lung machine use.
However, Gardner, who is also a spokesman for the American Heart
Association, says the study's findings do not prove bypass surgery leads to
a long-term decline in mental ability.
"I'd put this study in the category of interesting, but preliminary,"
Gardner says. "It's interesting because they've explained a pathological
condition that seems to occur, but I don't think this study, in particular,
is important to proving that heart surgery is dangerous to the brain."
He points out that the study looked at patients' mental ability just six
weeks after the operation, and did not assess whether they would recover
later.
Patients, Gardner says, frequently suffer depression or confusion after
surgery. And, he adds, the study failed to answer whether higher levels of
endotoxins in the bloodstream are common only in heart surgery or also other
major operations, such as removal of a tumor.
Gardner cites research presented last month by a team from Johns Hopkins
University that looked at bypass patients and a control group of heart
disease patients that did not have surgery. The Hopkins researchers found
that whether the patients had surgery had no bearing on changes in mental
ability measured a year later.
Most bypass surgery is performed on a stopped heart while a heart-lung
machine keeps the patient alive, the American Heart Association says.
However, the number of procedures performed without a pump, while the heart
is beating, is increasing.
