FOR IMMEDIATE RELEASE
November 17, 2008
Contact: Christine Guilfoy
Office: (301) 634-7253
cguilfoy@the-aps.org
Hypertension Develops Early, Silently, In
African-American Men
How blood pressure is measured may be the
key to early detection
Study points to central blood pressure as
key to screening
BETHESDA, Md. (Nov. 17, 2008) − Young and
healthy African-American men have higher central blood pressure and their
blood vessels are stiffer compared to their white counterparts, signs that
the African American men are developing hypertension early and with little
outward sign, according to a new study. While the study found that central
blood pressure -- the pressure in the aorta, near the heart -- was higher in
the African-American men, the study found no difference in brachial blood
pressure -- measured on the arm -- between the two groups.
Taken together, the findings suggest that hypertension
(high blood pressure) may be developing undetected in young African-American
men and that measuring central blood pressure may be a better means of
detecting the problem as it develops.
“Central blood pressure holds greater prognostic value
than conventional brachial blood pressure as central pressure more aptly
reflects the load encountered by the heart,” the authors explained. “Thus,
brachial blood pressure may neglect important information on cardiovascular
burden and response to therapy in African-American men.”
The study, “Racial differences in central blood
pressure and vascular function in young men” was carried out by Kevin S.
Heffernan, Sae Young Jae, Kenneth R. Wilund, Jeffrey A. Woods and Bo
Fernhall, at the University of Illinois, Urbana-Champaign. The study appears
online in the American Journal of Physiology-Heart and Circulatory
Physiology, published by The American Physiological Society. Dr.
Heffernan has since moved to Tufts Medical Center in Boston. Dr. Jae is also
affiliated with the University of Seoul.
‘Silent killer’
African-American men have higher levels of hypertension
than white men. Hypertension is known as the silent killer because it can
develop without the individual knowing it. According to the U.S. Centers for
Disease Control and Prevention, hypertension is a major risk factor for
heart disease, stroke, congestive heart failure, and kidney disease.
In 2002, hypertension was listed as a primary or contributing cause
of death for 277,000 Americans.
The University of Illinois researchers hypothesized
that the blood vessels of the black men would show greater dysfunction than
the white men, even though both groups were young and equally healthy and
fit. The vascular damage they looked for included stiffening and thickening
of the blood vessels. These conditions result in pulsatile (not smooth)
blood flow (and at higher pressure) to organs. The pressure can
damage the organs over time.
Both groups healthy
The study included 55 young men, 30 white and 25
African-American. Most were university seniors. The average age was 23.
There were no differences between the groups on a variety of measures,
including heart rate, cardiorespiratory fitness, body mass index, body fat,
blood lipids and glucose levels.
The researchers measured vascular function in a variety
of ways, including:
-
aortic blood pressure and stiffness
-
brachial blood pressure
-
carotid artery blood pressure
-
carotid artery thickness and stiffness
They found the African-American men had similar
brachial blood pressure, compared to the white men, but they had
significantly higher:
-
Central blood pressure, a measure of the pressure found in
the artery, near the heart. The researchers used an instrument that
takes blood pressure at the wrist and then calculates the central blood
pressure.
-
Carotid artery pressure. The carotid artery runs through
the neck.
The African-American men, unlike the white men, also
showed signs of early vascular damage that could lead to hypertension. For
example, they had:
-
Thicker carotid arteries, a sign of vascular damage that
is usually found in older individuals and associated with
atherosclerosis.
-
Stiffer arteries, which are associated with high blood
pressure. When the heart beats, blood flows through stiff arteries at
greater speed and pressure. Elastic arteries provide a smoother blood
flow and help prevent damage to organs receiving the blood and place
less stress on the heart.
-
Less change in diameter of the arteries when the heart
beats, another measure of vascular stiffness. A healthy artery is more
elastic will change in size as the blood flows through with each beat of
the heart.
“Although having a similar cardiovascular risk factor
profile as young white men, diffuse macrovascular and microvascular
dysfunction is present at a young age in apparently healthy African American
men,” the authors wrote. “Values seen are comparable to values often
reported in older individuals or individuals with more advanced hypertensive
disease,” they said.
These results do not shed light on why this happens to
young and fit African-American men, Heffernan said. There may be
environmental differences, such as differences in diet, which were not
examined as part of this study, he said.
Editor’s Notes: To arrange an interview with Dr.
Heffernan, please contact Christine Guilfoy at
cguilfoy@the-aps.org or (301) 634-7253.
A fuller audio interview with Dr. Heffernan is
available in Episode 15 of the APS podcast, Life Lines, at
www.lifelines.tv.
Funding: American Heart Association and the
American College of Sports Medicine
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society (APS) has been an
integral part of this scientific discovery process since it was established
in 1887.
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