Predictors of target organ damage in hypertensive blacks and whites.

The purpose of this study was to evaluate the association of the insulin resistance syndrome with both blood pressure and target organ damage in blacks and whites with essential hypertension. Eighty-two black and 63 white French Canadian patients were studied. None had diabetes, and antihypertensive medications had been discontinued for >/=1 week. Measurements included 24-hour blood pressure monitoring, fasting plasma lipids, insulin sensitivity determined with the Bergman minimal model, echocardiogram, microalbumin excretion, and inulin and lithium clearances. Compared with the white French Canadians, black patients had an attenuated nighttime reduction in blood pressure (P<0.02), increased cardiac dimensions (P<0.001), greater microalbumin excretion (P<0.05), increased inulin clearance (indicative of glomerular hyperfiltration; P<0.001), and decreased lithium clearance (indicative of increased sodium reabsorption in the proximal tubule; P<0.001). Blood pressure levels were not related to insulin resistance; although in blacks, the nighttime reduction in systolic blood pressure was inversely related to fasting plasma insulin (r=-0.18, P<0.04). In a stepwise multivariate analysis (including blood pressure levels and components of the insulin resistance syndrome as independent variables), race was the strongest predictor of left ventricular mass (r=0.53, P<0.000), relative wall thickness (r=0.49, P<0.000), and both inulin (r=0.53, P<0.000) and lithium (r=0.41, P<0.000) clearances. Nighttime systolic blood pressure was also a significant determinant of concentric left ventricular hypertrophy (r=0.37, P<0.000). In blacks, microalbumin excretion was related to insulin resistance. These observations are consistent with the hypothesis that there is a genetic contribution to cardiac hypertrophy, glomerular hyperfiltration, and sodium retention in blacks with essential hypertension.

Arterial pressure, left ventricular mass, and aldosterone in essential hypertension.

The purpose of the present study was to evaluate the relationship of aldosterone to blood pressure and left ventricular size in black American (n=109) and white French Canadian (n=73) patients with essential hypertension. Measurements were obtained with patients off antihypertensive medications and included 24-hour blood pressure monitoring, plasma renin activity and aldosterone, and an echocardiogram. Compared with the French Canadians, the black Americans had higher body mass indexes, higher systolic blood pressures, attenuated nighttime reduction of blood pressure, and lower serum potassium concentrations (P:<0.01 for each). Left ventricular mass index, posterior wall thickness, interventricular septal thickness, and relative wall thickness were also greater (P:<0.01 for each) in the black American patients. Supine and standing plasma renin activity was lower (P:<0.01 and P:<0.05, respectively) in the black Americans, whereas supine plasma aldosterone concentrations did not differ, and standing plasma aldosterone was greater (P:<0.05) in the black Americans (9.2+/-0.7 ng/dL) than in the French Canadians (7.3+/-0.6 ng/dL). In the black Americans, supine plasma aldosterone was positively correlated with nighttime systolic (r=0.30; P:<0.01) and diastolic (r=0.39; P:<0.001) blood pressures and inversely correlated with the nocturnal decline of systolic (r=-0.29; P:<0.01) and diastolic (r=-0.37; P:<0.001) blood pressures. In the black Americans, standing plasma aldosterone was positively correlated with left ventricular mass index (r=0.36; P:<0.001), posterior wall thickness (r=0.33; P:<0.01), and interventricular septal thickness (r=0.26; P:<0.05). When the black American patients were divided into obese and nonobese groups, significant correlations between plasma aldosterone and both blood pressure and cardiac mass were observed only in the obese. In the French Canadians, overall, plasma aldosterone did not correlate with either blood pressure or any measures of heart size. However, among obese French Canadians, supine plasma aldosterone correlated with nighttime diastolic (r=0.53, P:<0.02) and systolic (r=0.44, P:<0.01) blood pressures but not with cardiac mass. These results are consistent with the hypothesis that aldosterone contributes to elevated arterial pressure in obese black American and obese white French Canadian patients with essential hypertension and to the attenuated nocturnal decline of blood pressure and left ventricular hypertrophy in obese, hypertensive black Americans.

Genetic determinants of hypertension: identification of candidate phenotypes.

Our long-term objective is to identify genes whose expression results in hypertension and in phenotypic changes that may contribute to hypertension. The purpose of the present study was to describe evidence for the heritability of hypertension-related phenotypes in hypertensive, hyperlipidemic black sib pairs. Outpatient anthropomorphic measurements were obtained in >200 affected sib pairs. In addition, 68 of these sib pairs were studied under controlled, standardized conditions at an inpatient clinical research center while off both antihypertensive and lipid-lowering medications. Heritability was estimated on the basis of sib-sib correlations and with an association model. Higher heritability estimates for blood pressure were observed with multiple measurements averaged over 24 hours than with measurements at a single time point, and heritability estimates for nighttime blood pressures were higher than those for daytime blood pressures. Heritability estimates for several of the phenotypes were augmented by obtaining measurements in response to a standardized stimulus, including (1) blood pressure responses to the assumption of upright posture, standardized psychological stress, and norepinephrine infusion; (2) plasma renin, aldosterone, epinephrine, and cAMP and cGMP responses to the assumption of upright posture; (3) para-aminohippurate and inulin clearances in response to norepinephrine infusion; and (4) plasma arginine vasopressin in response to NaCl infusion. High heritability estimates were also observed for various measures of body size and body fat, left ventricular size, cardiac index, stroke volume, total peripheral resistance, and serum concentrations of LDL and HDL cholesterol and leptin. These heritability estimates identify the hypertension-related phenotypes that may facilitate the identification of specific genetic determinants of hypertension in blacks with hyperlipidemia.

Glomerular hyperfiltration in hypertensive African Americans.

The incidence of end-stage renal disease attributable to hypertension is 5-fold greater in African Americans than in whites. To determine whether glomerular hyperfiltration is an antecedent to renal failure, we compared responses of renal blood flow and glomerular filtration rate to graded infusions of norepinephrine (0. 01, 0.025, and 0.05 microg. kg(-1). min(-1) for 30 minutes each) in 29 African Americans and 33 age-matched French Canadian whites with essential hypertension. Renal blood flow and glomerular filtration rate were measured by using a constant-infusion technique of PAH and inulin, respectively. Studies were conducted on an inpatient clinical research center, and antihypertensive medications had been discontinued for at least 1 week. Based on 24-hour blood pressure monitoring, nighttime blood pressures decreased (P<0.01) in the French Canadians but not in the African Americans. Baseline renal blood flow was higher (P<0.05) in the African Americans (1310+/-127 mL. min(-1) per 1.73 m(2)) than in the French Canadians (1024+/-42 mL. min(-1) per 1.73 m(2)); baseline glomerular filtration rate was also higher (P<0.01) in the African Americans (140+/-4 versus 121+/-4 mL. min(-1) per 1.73 m(2)). In response to norepinephrine-induced blood pressure increases, renal blood flow was autoregulated and did not change in either patient group. In the African Americans, glomerular filtration rate increased (P<0.01) to 167 mL. min(-1) per 1.73 m(2) during the first norepinephrine infusion, without subsequent change. In contrast, glomerular filtration rate did not change with norepinephrine-induced increases of blood pressure in the French Canadians. In the African Americans, the elevation of baseline glomerular filtration rate, with a further increase in response to norepinephrine, may be indicative of glomerular hyperfiltration. Glomerular hyperfiltration and lack of nocturnal blood pressure decline may contribute to the higher incidence of end-stage renal disease in hypertensive African Americans.

Hypertension control and access to medical care in the inner city.

OBJECTIVES: This study assessed hypertension control among high-risk African Americans. METHODS: We interviewed 583 African Americans aged 18 years and older residing in 438 randomly selected inner-city households. RESULTS: Forty-two percent of the respondents were hypertensive. Blood pressure was uncontrolled in 74% of hypertensive persons, although 64% of hypertensive persons reported having seen a physician within the previous 3 months. Hypertension control was associated with female gender and higher socioeconomic strata but not with public versus private sources of medical care. CONCLUSIONS: Hypertension control is inadequate in this population, although health care services are used frequently. Hypertension control efforts should focus on the effectiveness of health care delivery.

Dietary sodium and blood pressure: interactions with other nutrients.

This paper reviews the evidence that salt sensitivity of blood pressure is related both to the anion ingested with sodium as well as to other components of the diet. In several experimental models of salt-sensitive hypertension and in humans, blood pressure is not increased by a high sodium intake provided with anions other than chloride. Salt-induced increase of blood pressure depends on the concomitant ingestion of both sodium and chloride. Both epidemiologic and clinical evidence suggest that sodium chloride-induced increases of blood pressure are augmented by diets deficient in potassium or calcium. In experimental animals, a high intake of simple carbohydrates also augments sodium chloride sensitivity of blood pressure. These observations indicate that the effect of dietary sodium on blood pressure is modulated by other components of the diet.

Incorporating socio-economic and risk factor diversity into the development of an African-American community blood pressure control program.

OBJECTIVE: To develop culturally competent community based blood pressure control programs for inner-city African Americans. DESIGN: Cross sectional study of randomly selected households from three experimental and three control communities. SETTING: Very low, moderately low and moderate socio-economic status (SES) inner-city communities in Chicago, Illinois. PARTICIPANTS: 957 African Americans adults, aged 18 and over from target communities. MAIN OUTCOME MEASURE: Household health assessments included employment, education and other demographic information, history of hypertension, disease prevalence, health behaviors, risk factor prevalence, stress, coping/John Henryism, social support, health care utilization and standardized assessments of blood pressure, height, and weight. RESULTS: There were no significant gender differences in blood pressure levels. Men had more hypertension than women, and women in the very low SES community had significantly more hypertension than women in the moderately low SES community. There was significantly more hypertension overall in the moderately low SES community. Age, education and BMI were the only factors significantly associated with systolic and diastolic blood pressure in all three communities. The very low SES community had significantly more obesity and more uninsured persons than the other communities. CONCLUSIONS: Intraracial diversity is an important factor to be considered in the development of community blood pressure control programs for African Americans. Age, gender, educational background and SES play a major role in influencing health behaviors and access to health care.

Planning for a community-based hypertension control program in the inner city.

Uncontrolled hypertension is a significant problem among African-Americans residing in inner city environments. To help address the problem, we are developing community-based hypertension control programs in African-American communities located in Milwaukee, Wisconsin and Chicago, Illinois. The Milwaukee program focuses on an entire, diverse inner city area, while the Chicago program is targeted to several more homogeneous African-American neighborhoods. The investigators hypothesize that the success of a hypertension control program will depend on carefully tailoring the educational approaches to the specific characteristics of the target area. Therefore, the study areas that have been selected differ with regard to community size and diversity, community 'stressors' (poverty, unemployment, crime, etc), and types of organizations which are present in the community. This paper describes the background and the rationale for community hypertension control programs in the inner city. The initial approaches to establishing the program by developing interfaces with the community and the gathering of baseline data through household surveys are described.

Insulin and hypertensive cardiovascular disease.

Resistance to insulin-stimulated glucose uptake is associated with several cardiovascular disease risk factors, including hypertension, dyslipidemia, and alterations of the blood clotting cascade that accentuate thrombosis. This constellation of risk factors may be recognized at young ages and is at least in part heritable. Recognition of this syndrome dictates that preventive and therapeutic strategies should address overall cardiovascular disease risk. In patients with hypertension or diabetes, additional clinical trials are required to identify those interventions that will most effectively reduce not only overall risk but also definitive cardiovascular disease endpoints.

Gender differences in obesity-related cardiovascular disease risk factors among participants in a weight loss programme.

Obesity is associated with increased cardiovascular disease risk factors in some, but not all, individuals, and blood pressure responses to weight loss are also heterogeneous. The purposes of this study are: (i) to assess associations among cardiovascular disease risk factors in obese individuals and (ii) to determine clinical predictors of a hypotensive response to weight loss. The study was undertaken in 155 consecutive patients enrolled in a weight loss programme. Individuals entering the programme were predominantly women and differences were found between men and women who joined the programme. Before weight loss, obese men exhibited higher cardiovascular disease risk factors (body mass indices, waist-to-hip ratios, systolic and diastolic blood pressures, serum glucose, and lower HDL cholesterol) than did women. However, among women, but not men, cardiovascular disease risk factors clustered in individuals with higher waist-to-hip ratios. Furthermore, in contrast to men, a higher waist-to-hip ratio in women was associated with a reduction in systolic blood pressure in response to weight loss. While it is possible that selection bias may explain gender differences among programme participants, and smaller numbers of men available for study may obscure associations in men, our data document that even at high levels of obesity, waist-to-hip ratios are associated with hypertension and a clustering of cardiovascular disease risk factors in women. We conclude that body fat distribution, as reflected in waist-to-hip ratios, may be a more robust risk factor in female than in male obese patients and that this risk factor extends to those women with high levels of obesity.

Nutrition and hypertension prevention.

Hypertension has been related to both obesity and a high salt intake. Evidence for the associations of blood pressure with body weight and dietary salt intake is summarized. In both adolescents and adults correlations between blood pressure and weight are highly significant, and in longitudinal studies change in blood pressure over time is correlated with change in weight. Correlations between salt intake and blood pressure are less striking, and the results of trials of modest salt restriction demonstrate a small but significant effect on blood pressure. Individuals vary in their susceptibility to salt, and hypertensive individuals are more responsive than normotensive individuals. Dietary deficiencies of potassium and calcium may amplify the effect of a high salt intake on blood pressure. Animal models provide compelling evidence for a genetic component to salt sensitivity of blood pressure. In two hypertension prevention trials, change in blood pressure was more convincingly related to change in weight than to change in dietary salt. Avoidance of obesity, or weight reduction in overweight individuals, should be key strategies for hypertension prevention. Avoidance of salt excess is also appropriate, although currently available trial data do not justify a recommendation of rigorous salt restriction for the entire population.

The association between Type A behavior and change in coronary risk factors among young adults.

The association of Type A/B behavior pattern and changes in blood pressure, total serum cholesterol, serum triglyceride, body mass, and smoking was estimated in a cohort of 375 young Black and White men and women from a rural county in Central Kentucky between 1978-79 and 1985-88. Type A participants experienced significant increases in systolic (2.90 +/- 1.29 mmHg) and diastolic (3.80 +/- 1.17 mmHg) blood pressure and in cigarette smoking (3.26 +/- 0.89 cigarettes per day) over the eight-year follow-up period, but Type B participants experienced no change. Type A and B individuals showed similar changes in total serum cholesterol, serum triglyceride, or body mass. Differences between behavioral types in blood pressure were present for women but not men, and for Blacks but not for Whites. These findings suggest a possible significance of the Type A pattern for the development of cardiovascular risk of young adults.

Reduction of left ventricular preload by lower body negative pressure alters Doppler transmitral filling patterns.

The objective of this study was to evaluate the effect of alterations in preload induced by lower body negative pressure on Doppler transmitral filling patterns. Echocardiograms and Doppler recordings were performed in 18 normal young men (aged 23 to 32 years) during various levels of lower body negative pressure (0, -20 and -50 mm Hg). Lower body negative pressure induced a reduction in diastolic velocity integral (from 12.17 +/- 0.79 to 8.42 +/- 0.71 cm, p = 0.0067) and consequently left ventricular diastolic diameter (from 5.11 +/- 0.09 to 4.45 +/- 0.1 cm, p less than 0.0001). There was a significant reflex increase in heart rate from 59.9 +/- 1.9 to 77.1 +/- 2.4 beats/min (p less than 0.0001), but blood pressure was unchanged. This reduction in preload altered Doppler transmittral filling patterns as follows: 1) peak early velocity (E) decreased from 59.2 +/- 3.8 to 39.1 +/- 1.7 cm/s (p less than 0.0001); 2) atrial filing velocity (A) was unchanged (35.58 +/- 1.5 to 33.52 +/- 1.4 cm/s, p = 0.517); 3) E/A ratio decreased from 1.7 +/- 0.13 to 1.19 +/- 0.08 (p = 0.0087); 4) mean acceleration (from 482 +/- 37 to 390 +/- 27 cm/s2, p = 0.03) and mean deceleration (from 327 +/- 31 to 169 +/- 21 cm/s2, p less than 0.001) of the early filling wave were significantly reduced; and 5) peak acceleration (from 907 +/- 42 to 829 +/- 29 cm/s2) and peak deceleration (from 771 +/- 94 to 547 +/- 76 cm/s2) also decreased, but not significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

The measurement of physical activity in young children.

Two studies were conducted to determine the validity of various measures of physical activity in young children. In Study 1, 21 preschool children were utilized to explore how well measures of children's activity obtained from parents, teachers, and the children predicted observed behavior at school and in the home. Study 2 (n = 51 preschool children) focused on the predictive validity of the Caltrac motion sensor. In both studies, detailed minute-by-minute ratings of children's activity in Study 1 were generally ineffective in predicting observed physical activity. Children's activity preferences, however, were significantly related to the proportion of high intensity physical activity performed. In Study 2, there was a significant relationship (r = .86, p less than .0001) between Caltrac readings and observed physical activity. This correlation was similar for boys and girls, normal and overweight children, and younger and older children. These findings suggest that the Caltrac monitor may provide a valid index of individual differences in physical activity in young children.

The use of itemized register tapes for analysis of household food acquisition patterns prompted by children.

This article describes a method of collecting and analyzing itemized grocery receipts for use in epidemiological studies. As part of a larger study of children's food acquisition and exercise habits related to cardiovascular disease, a sample of 50 families was asked to keep itemized grocery receipts for a 2-week period. To control for bias as a result of differences in food consumption and food acquisition, mothers were asked to log meals eaten away from home, food used from home production, and gifts of foods. Items on the receipts were coded according to food groups and whether they represented child-prompted purchases. The items were expressed in terms of the percentage of the food dollar each category represented. Data from the survey were compared with data collected in national surveys. The method was found to be relatively non-intrusive, easily carried out, and eliminated many of the problems associated with non-response, respondent burden, and recall characteristic of other food account methods. It is suggested as a feasible way of characterizing the family food environment in epidemiological studies.

Treatment of high blood pressure in the young.

Children with high normal or high BP should also be evaluated for other cardiovascular risk factors, and interventions should address overall cardiovascular risk. Nonpharmacologic interventions include weight reduction when appropriate, avoidance of dietary salt excess, and dynamic exercise. Drug treatment should be required in a minority of children with hypertension. There are concerns about the longterm effects of drug therapy on lipid and carbohydrate metabolism and on physical and cognitive growth and development. Beta adrenergic antagonists and diuretics are usually the first line drugs to be added to the nonpharmacologic therapeutic strategies for BP control in children. After a sufficient period of BP control, a stepped-down approach and discontinuation of drug therapy should be considered.

Baroreceptor sensitivity in prehypertensive young adults.

Decreased baroreceptor reflex sensitivity has been implicated in the pathogenesis of hypertension. The purpose of this study is to determine if alterations of baroreceptor function precede the development of hypertension in humans. Baroreceptor function was evaluated in 13 young adult white men with relatively high blood pressures sustained for 12 to 15 years and 12 age-matched men with sustained relatively low blood pressures. High pressure baroreceptor activity was evaluated by measuring change in pulse interval in response to decreases and increases of arterial pressure, induced by graded infusions of nitroprusside and angiotensin II, respectively. In response to both agents, baroreceptor slopes did not differ in the high and low blood pressure groups. Plasma norepinephrine also increased similarly in both blood pressure groups in response to nitroprusside. To study low-pressure baroreceptor function, responses to graded levels of lower-body negative pressure (LBNP) were measured. Comparing both blood pressure groups, there were similar increases of heart rate, total peripheral resistance, and plasma norepinephrine in response to LBNP. Both blood pressure groups also had similar increases of heart rate and blood pressure in response to isometric (handgrip) exercise. Thus, high-pressure and low-pressure baroreceptor function is not altered in prehypertensive young adults. However, continued follow-up will be required to determine if these individuals with sustained relatively high blood pressures are truly prehypertensive.

Blood pressure trends associated with changes in height and weight from early adolescence to young adulthood.

In children, blood pressure is more closely related to height and indices of maturation than to age. This study extends observations on the relationship between height, weight, maturation and blood pressure during early adolescence into young adulthood. Standardized measurements of blood pressure, height, and weight were initially obtained in all 14-15 year old adolescents (N = 304) in a rural Kentucky school system. Measurements were repeated 5 and 8 years later. Adolescents with relatively high blood pressures continued to have higher blood pressures as young adults. Increases in systolic and diastolic blood pressure over time were related to increases of relative weight in both sexes (p less than 0.0001 and p less than 0.005, respectively), and in males increases of systolic blood pressure were related to increases of height (p less than 0.005). However, males who attained their full height at younger ages had higher blood pressures both during adolescence and subsequently, as young adults. Thus blood pressure of young adults is related to blood pressure in adolescence, relative weight and change in relative weight since adolescence, and in males to age of maturation as determined by the age at which adult height is attained.

Impact of a rural high blood pressure control program on hypertension control and cardiovascular disease mortality.

Kentucky is a predominantly rural state with relatively high death rates from hypertension and cardiovascular disease. We report the results of a community-based high blood pressure control educational program undertaken in two rural counties of southeastern Kentucky. In the intervention counties, systolic and diastolic blood pressures of both men and women decreased despite the five-year increase in age; moreover, hypertension was better controlled after the program, and substantial decreases in deaths due to cardiovascular disease were seen. These differences were greater among men in the two regions than among women. The results of this program suggest that, in sparsely populated rural areas, existing resources and programs can be successfully utilized in a communitywide cardiovascular disease risk reduction educational program.