A lowered ability of blood vessels in the arm to respond to stress is associated with increased heart size -- an important risk factor for heart disease, according to a Johns Hopkins study.
In the work, on 35 people ages 55 to 75 with mild hypertension, the researchers used magnetic resonance imaging (MRI) to measure the size of the heart's left ventricle, its main pumping chamber. Next, they temporarily put a tight cuff on the patients' left arms to stop blood flow, then used ultrasound to measure the amount of blood flow once the cuff was loosened. This test was a measure of the ability of endothelial cells lining the blood vessels to expand or contract in response to stress and other physiological demands such as exercise.
The results? The amount of blood flow through blood vessels in the arm after the cuff was released was tied directly to the heart size. The better the ability of the vessels to respond to the stress of increased blood flow when the cuff was released, the more normal the heart size, and vice versa. An enlarged heart is dangerous and contributes to a person's risk of heart attack, stroke or heart failure.
"The reduced ability to respond to increased blood flow in these peripheral blood vessels may be an early marker for cardiac problems," says Kerry J. Stewart, Ed.D., senior author of the study and director of cardiac rehabilitation and clinical exercise physiology at Hopkins. "This dysfunction causes resistance to blood flow. As a result, the heart works harder and becomes enlarged. These findings suggest that it may be important to diagnose and treat problems in the peripheral blood vessels as a way of preventing or reducing the health consequences of an enlarged heart."
Stewart and his team are studying whether regular exercise can improve the responses of peripheral blood vessels to stress.
Related Web sites:
American College of Cardiology 50th Scientific Sessions -- http://www.acc.org/2001ann_meeting/home.htm
Information on Heart Disease Treatments at Johns Hopkins -- http://www.hopkinsmedicine.org/heartdisease.html
Materials provided by Johns Hopkins Medical Institutions. Note: Content may be edited for style and length.
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