A blood pressure reading taken during exercise is a more accurate test for early heart disease than one taken at rest, according to a Hopkins study presented Sept. 14 at the annual meeting of the American Association of Cardiovascular and Pulmonary Rehabilitation in Minneapolis.
The study, conducted by researchers at the School of Medicine, showed that a high pulse pressure--defined as the difference between systolic blood pressure (the upper number) and diastolic blood pressure (the lower number)--during exercise was associated with a dysfunction of the endothelial cells lining the blood vessels. These cells control the ability of the blood vessels to dilate, or expand, which allows more blood to flow during periods of stress. Increased pulse pressure is also an indicator of blood-vessel stiffening, which may be a marker of early heart disease. Recent epidemiological studies have shown that pulse pressure is the leading risk factor for cardiovascular disease in the elderly.
"Most clinicians focus on the patient's blood pressure during rest, but our study shows that exaggerated blood pressure during exercise is a more sensitive marker for resistance to blood flow through the arteries, which is a possible sign of atherosclerosis (hardening of the arteries)," says Kerry J. Stewart, lead author of the study and director of cardiac rehabilitation and clinical exercise physiology at Hopkins. "The higher the pulse pressure in response to exercise, the more likely the patient was to have blood vessels that did not expand as expected."
If cells lining the blood vessels are unable to respond well to the increase in blood flow associated with stress and exercise, the heart must work harder and can become enlarged, Stewart says. An enlarged heart heightens a person's risk of heart attack, stroke or heart failure.
For the study, Stewart and colleagues evaluated 35 adults, ages 55 to 75, who had untreated mild hypertension but were otherwise healthy. Researchers measured the participants' resting blood pressure during four or five visits at least one week apart, then compared those measurements to blood pressure readings recorded during maximal effort treadmill exercise tests. They also used ultrasound to measure how well the vessels in the subjects' arms would expand in response to stress.
Other authors of the study were Anita C. Bacher, Katherine L. Turner, Jamie R. DeRegis, Harry A. Silber, Edward P. Shapiro, Jidong Sung and Pamela Ouyang.
Established in 1985, the American Association of Cardiovascular and Pulmonary Rehabilitation represents more than 3,000 health care professionals worldwide engaged in education, prevention, rehabilitation, research and disease management activities in cardiovascular and pulmonary rehabilitation and prevention programs.