Stress
Impedes Proper Blood Flow
NEW YORK (Reuters Health) - Stress appears to inhibit the ability
of blood vessels to expand--a problem that may explain why extremely
stressful events can precipitate heart attacks, new study findings
suggest.
Sudden stress, such as that related to anger, bereavement or war,
can trigger heart attacks or sudden cardiac death, according to
Dr. Georg Noll of the University Hospital in Zurich, Switzerland.
However, it is not clear how such stressful events affect the heart.
In the study, Noll and his team used ultrasound to look at the
blood vessels of 23 healthy people as they performed a stressful
task--quickly pushing buttons in response to flashing lights.
Typically, the endothelium--the lining of the blood vessels--can
boost blood flow as needed to supply oxygen to muscle, including
the heart.
The investigators found that the stress cut the ability of the
endothelium to respond by 50% for about 45 minutes. The 3-minute
mental stress test also caused both blood pressure and heart rate
to temporarily increase, according to the report released May
21st in the rapid access issue of Circulation: Journal of the
American Heart Association.
Further tests suggested that blocking a receptor called ETa,
which is found on cells of the endothelium, could block the blood
vessel-constricting effects of stress.
"This study provides the first evidence that sudden mental stress
induces prolonged endothelial dysfunction via activation of ETa
receptors," the authors report.
The finding provides a clue as to why stressful events could
spell trouble for people who already have narrowed or blocked
arteries. Stress may act to compound already restricted blood
flow that could lead to a heart attack or stroke.
Blocking ETa receptors could "represent a new therapeutic strategy"
in the prevention of heart disease-related problems, Noll and
colleagues conclude.
SOURCE: Circulation 2002;10.1161/01.CIR.0000021598.15895.34.
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