Page 824 - Cardiac Nursing

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800 PA R T V / Health Promotion and Disease Prevention

for men. The influence of family history is seen in children as well
Table 35-1 ■ CLASSIFICATION OF BLOOD PRESSURE as adults. 19,20 Recent genetic studies suggest that rather than a sin-
FOR ADULTS gle genetic variant, alleles at many different loci contribute to
HTN, with the combinations of causative alleles varying between
BP Classification SBP (mm Hg) DBP (mm Hg)
individuals. Among the most studied genetic markers for the
Normal 120 and 80 pathogenesis of HTN are the renin–angiotensin system, salt in-
Prehypertension 120–139 or 80–89 take, CVD, obesity and insulin resistance, the sympathetic nervous
Stage 1 Hypertension 140–159 or 90–99 system, and endothelial dysfunction. 21
Stage 2 Hypertension 160 or 100
Ethnic and Geographic Differences
From Chobanian, A. V., Bakris, G. L., Black, H. R., et al. (2003). The Seventh Report Geographic differences in the prevalence of HTN have been de-
of the Joint National Committee on Prevention, Detection, Evaluation, and
Treatment of High Blood Pressure: The JNC 7 report. JAMA, 289(19), 2560–2572. scribed for different regions within the United States as well as
(Erratum in JAMA, 2003, 290[2], 197.) across the world. When comparing across non-Hispanic White,
non-Hispanic Black, and Mexican American ethnic groups in the
United States, the prevalence of HTN was highest among non-
utero, although a meta-analysis of 55 studies of birth weight and Hispanic Black women (46.6%) and men (42.6%) and lowest
BP later in life did not support this so-called fetal origins hypoth- among Mexican American women (31.4%) and men (28.7%). 1
esis. 11–13 Because HTN in children is defined as a BP greater than Within the United States, HTN prevalence, associated stroke
the 95th percentile for a child of any given age and height, the ini- mortality, and all-cause mortality vary in geographic patterns and
tial incidence of HTN in children is automatically 5%. Normally, are higher in the Southeast than other regions of the United States.
BP increases in children at a rate between 1 and 4 mm Hg per year Ten of 11 states in the southeastern United States, the “Stroke
for both SBP and DBP and then levels off after age 18 to 20 years. Belt,” have stroke mortality rates 10% above the national mean.
Children whose BP consistently falls above the 95th percentile for Contributors to this pattern include geographic variations in obe-
height, gender, and age are at risk for sustained HTN and should sity, physical inactivity, and salt and nutritional intake but not in
be evaluated and possibly treated. 10 HTN treatment or control. 2,3,22
In adults, BP tends to increase with age. 2,3 The prevalence of A review of the global burden of HTN revealed that regions
HTN increases with advancing age to the point where more than with the highest estimated prevalence of HTN had roughly twice
half of the people aged 60 to 69 years and approximately three the rate compared with regions with the lowest estimated preva-
23
fourths of those aged 70 years and older are affected. 14 The age- lence. In men, the highest estimated prevalence was in the Latin
related rise in SBP, often manifesting as isolated systolic HTN, is America and Caribbean region, whereas for women the highest es-
primarily responsible for an increase in both incidence and preva- timated prevalence was in the former socialist economies. The
8
lence of HTN with increasing age. Overall, women have a lowest estimated prevalence of HTN for both men and women
slightly higher prevalence of HTN (33.6%) than do men was in the region “other Asian islands” (i.e., Korea, Thailand, and
1
(33.2%). However, the age-adjusted percent for women is 28%, Taiwan). 23 Existing data suggest that the prevalence of HTN has
3
and for men, it is 30%. Although rates of HTN treatment are increased in economically developing countries during the past
higher among women (58%) compared with men (52%), men decade. 23 Differences in HTN rates across regions may be caused
achieved higher rates of HTN control (66%) than women by differences in BP measurement and treatment, genetics,
(63%). 3 lifestyle choices, or other confounding variables.
Data from the Framingham and other epidemiologic studies
have shown that as body weight increases, so do SBP and DBP in Income and Education
children and adults. 3,10,15–17 In the Bogalusa Study, children and An inverse relationship between socioeconomic status, including
adolescents who were overweight (body mass index [BMI] 85th educational level and income, and the prevalence of HTN has
percentile) were 2.4 times more likely to have HTN than those been documented. 24–27 The Atherosclerosis Risk in Communities
with BMI less than the 85th percentile. 16 NHANES III data re- Study of 10,091 Black and White Americans has even found a re-
vealed that the prevalence of HTN in men and women with BMI lationship between the stretch capacity (elasticity) of the carotid ar-
2
25 kg/m was 15%, whereas in men and women with a BMI teries and socioeconomic status, with persons in the lowest socioe-
2
15
30 kg/m prevalence was 42% and 38%, respectively. This re- conomic stratum having the greatest impairment of carotid
lationship between weight and BP is thought to be one of the rea- elasticity. 28 The impact of socioeconomic status on BP and other
sons that BP increases with age. cardiovascular risk factors is thought to be related to social, finan-
cial, and political barriers to health care and to adoption of low-risk
Family History and Genetic Factors lifestyles. 29,30
Family history of HTN has been used as an indicator of genetic
influence on HTN. With the progress on the human genome Hemodynamics of HTN
project, it is possible that we may be able to predict risk with more
precision; however, expense and issues of privacy must also be BP is the product of the amount of blood pumped by the heart
considered. Depending on how a positive family history of HTN each minute (cardiac output) and the degree of dilation or con-
is defined, a person with a positive history has a relative risk for striction of the arterioles (systemic vascular resistance). Arterial BP
18
HTN of between 2.4 and 5.0. The risks are greater when more is controlled over short time periods by the arterial baroreceptors
family members have HTN and if these family members had that sense changes in pressure within major arteries and then
HTN diagnosed before the age of 55 years. The risk associated through neurohumoral feedback mechanisms, which modulate
with a positive family history is slightly greater for women than heart rate, myocardial contractility, and vascular smooth muscle