A Stress-Test Warning Signal
Blood pressure reading tells of artery trouble, says new study
FRIDAY, Sept. 14, 2001 (HealthDayNews) -- How your blood pressure responds during an exercise stress test can be a warning sign of artery problems that could lead to heart attack or stroke, a study finds.
This response is measured by taking the difference between the systolic (highest) and diastolic (lowest) blood pressure readings; this gives you your pulse pressure, says Kerry J. Stewart, director of cardiac rehabilitation and clinical exercise physiology at the Johns Hopkins University School of Medicine.
Systolic pressure measures the force blood exerts on the artery walls when the heart beats, and diastolic pressure measures the force on the arteries between heartbeats.
An unusually high pulse pressure during an exercise test indicates problems with the endothelial cells that line the arteries, Stewart says in a paper that was prepared for the annual meeting of the American Association of Cardiovascular and Pulmonary Rehabilitation in Minneapolis. The meeting was canceled because of this week's terrorist attacks.
"The endothelial cells control the ability of the blood vessels to contract," Stewart explains. "We found a pretty strong correlation between pulse pressure and the ability of blood vessels to relax. You don't see that relationship in resting blood pressure, but during stress you get some very exaggerated responses."
Stewart's study included 35 people with moderately elevated blood pressure, an average of 140 over 85, which is just above the recommended safe level. They volunteered for maximum-effort treadmill exercises during which their blood pressure was monitored carefully, and ultrasound measured how well the arteries in the arms expanded in response to the stress. The people were between 55 and 75 years old.
There were some exaggerated responses to exercise, with systolic pressure going up to 250 or 260, Stewart says. But the key finding was that those with the highest pulse pressure had the least expansion of their arteries.
"That gives a reason to pay close attention to blood pressure during a stress test, rather than focusing on the electrocardiogram," Stewart says. "The pulse pressure does give more information about underlying cardiovascular health." An electrocardiogram registers the heart's electrical activity and can detect not only problems with and inflammations of the heart muscles but also coronary heart disease.
"Most cardiologists who do stress testing do pay attention to blood pressure," says Dr. Steven Bergmann, director of nuclear cardiology at Columbia Presbyterian Medical Center in New York City. "Clearly, it is important in determining the health of blood vessels."
Although electrocardiogram readings during exercise tests are not very good indicators of heart disease, he says, "blood pressure is very important in determining how the cardiovascular system responds to exercise."
But cardiologists do not usually focus on pulse pressure during exercise tests, Bergmann acknowledges.
"Pulse pressure is not something we usually quantify," he says, and the new study "is calling attention to something that should be looked at."
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