Race and gender influence ambulatory blood pressure patterns of adolescents

Interplay of Race and Neighborhood Deprivation on Ambulatory Blood Pressure in Young Adults

Background

Ambulatory blood pressure (BP) monitoring measures nighttime BP and BP dipping, which are superior to in-clinic BP for predicting cardiovascular disease (CVD), the leading cause of death in America. Compared with other racial/ethnic groups, Black Americans exhibit elevated nighttime BP and attenuated BP dipping, including in young adulthood. Social determinants of health contribute to disparities in CVD risk, but the contribution of neighborhood deprivation on nighttime BP is unclear. Therefore, we examined associations between neighborhood deprivation with nighttime BP and BP dipping in young Black and White adults.

Methods

We recruited 21 Black and 26 White participants (20 M/27 F, mean age: 21 years, body mass index: 25±4 kg/m2) for 24-hour ambulatory BP monitoring. We assessed nighttime BP and BP dipping (nighttime:daytime BP ratio). The area deprivation index (ADI) was used to measure neighborhood deprivation. Associations between ADI and ambulatory BP were examined.

Results

Black participants exhibited higher nighttime diastolic BP compared with White participants (63±8 mmHg vs 58±7 mmHg, p=0.003), and attenuated BP dipping ratios for both systolic (0.92±0.06 vs 0.86±0.05, p=0.001) and diastolic BP (0.86±0.09 vs 0.78±0.08, p=0.007). Black participants experienced greater neighborhood deprivation compared with White participants (ADI scores: 110±8 vs 97±21, p<0.001), and ADI was associated with attenuated systolic BP dipping (ρ=0.342, p=0.019).

Conclusions

Our findings suggest neighborhood deprivation may contribute to higher nighttime BP and attenuated BP dipping, which are prognostic of CVD, and more prevalent in Black adults. Targeted interventions to mitigate the effects of neighborhood deprivation may help to improve nighttime BP.

Clinical Trial Registry

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04576338.

Ethnic differences and heritability of blood pressure circadian rhythm in African and European American youth and young adults

BACKGROUND

The aim of this study was to investigate whether blood pressure (BP) circadian rhythm in African Americans differed from that in European Americans. We further examined the genetic and/or environmental sources of variances of the BP circadian rhythm parameters and the extent to which they depend on ethnicity or sex.

METHOD

Quantification of BP circadian rhythm was obtained using Fourier transformation from the ambulatory BP monitoring data of 760 individuals (mean age, 17.2 ± 3.3; 322 twin pairs and 116 singletons; 351 African Americans).

RESULTS

BP circadian rhythm showed a clear difference by ethnic group with African Americans having a lower amplitude (P = 1.5e-08), a lower percentage rhythm (P = 2.8e-11), a higher MESOR (P = 2.5e-05) and being more likely not to display circadian rhythm (P = 0.002) or not in phase (P = 0.003). Familial aggregation was identified for amplitude, percentage rhythm and acrophase with genetic factors and common environmental factors together accounting for 23 to 33% of the total variance of these BP circadian rhythm parameters. Unique environmental factors were the largest contributor explaining up to 67--77% of the total variance of these parameters. No sex or ethnicity difference in the variance components of BP circadian rhythm was observed.

CONCLUSION

This study suggests that ethnic differences in BP circadian rhythm already exist in youth with African Americans having a dampened circadian rhythm and better BP circadian rhythm may be achieved by changes in environmental factors.

Sustained high blood pressure and 24-h ambulatory blood pressure monitoring in Tanzanian adolescents

Estimates for prevalence of high blood pressure (BP) among adolescents in Africa vary widely and few studies, if any, have documented the results of the recommended stepwise BP screening. In this cross-sectional study in Tanzania, we aimed to estimate prevalence of sustained high BP in 3 public secondary schools using the American Academy of Pediatrics BP screening strategy. On Day 1, one screening automated office BP (AOBP) measurement (Step 1) was followed by two more AOBP measurements (Step 2). Repeat AOBP measurements were obtained after about one month on adolescents with high AOBP measurements on Day 1 (Step 3). Participants with sustained high BP underwent 24-h ambulatory BP monitoring (step 4). Of all 500 enrolled participants, the prevalence of high blood pressure at each step in the process was 36.6% (183), 25.6% (128), 10.2% (51), and 2.6%(13) respectively for Steps 1-4. All except 6 students completed all 4 steps of the BP screening algorithm as indicated. We conclude that diagnosis of hypertension in African adolescents should use multiple AOBP measurements over multiple days followed by 24-h ABPM. Screening for high BP in school settings appears to be feasible and could provide a platform for cardiovascular disease education and health promotion.

Hemodynamic and ECG responses to stress test in early adolescent athletes explain ethnicity-related cardiac differences

BACKGROUND

Ethnicity is an important determinant of athletes' cardiovascular adaptation. Black adolescent and adult athletes exhibit a left ventricular (LV) hypertrophy with a concentric remodelling higher than their Caucasian counterparts. Scant data, however, are available on race-related differences in hemodynamic response of adolescent athletes to exercise and its relation with heart remodelling. We evaluated if race-specific, sport-related structural and electrical remodelling in adolescent athletes of Caucasian and African ethnicity exclusively depends on race itself rather than on different cardiovascular responses to physical exercise.

METHODS

We examined 90 adolescent athletes, 60 Caucasian (WA) and 30 Black (BA). All participants underwent thorough clinical, echocardiographic and stress test evaluations.

RESULTS

BA had greater indexed LV mass (LVM/BSA) with increased relative wall thickness (RWT) implying a concentric remodelling. BA showed higher systolic blood pressure (SBP) compared to WA during the whole exercise test. ECG data showed that BA vs WA had a significant shorter QRS duration in each step considered with a significant greater QT dispersion. BA reached a higher relative pressure peak as compared to WA. RWT was strongly influenced by ethnicity and less by SBP at peak of exercise (PE), although LVM/BSA was significantly related to SBP at PE and just marginally to age and not significantly to race.

CONCLUSIONS

Black adolescent athletes showed higher SBP during all steps of exercise associated to a different trend. Ethnicity was the main determinant of RWT, suggesting that LV geometry is principally race-related rather than influenced by a different hemodynamic profile to physical activity.

Gender and Race Disparities in Cardiovascular Disease Risk Factors among New York City Adults: New York City Health and Nutrition Examination Survey (NYC HANES) 2013-2014

While gender and racial/ethnic disparities in cardiovascular disease (CVD) risk factors have each been well characterized, few studies have comprehensively examined how patterns of major CVD risk factors vary and intersect across gender and major racial/ethnic groups, considered together. Using data from New York City Health and Nutrition Examination Survey 2013-2014-a population-based, cross-sectional survey of NYC residents ages 20 years and older-we measured prevalence of obesity, hypertension, hypercholesterolemia, smoking, and diabetes across gender and race/ethnicity groups for 1527 individuals. We used logistic regression with predicted marginal to estimate age-adjusted prevalence ratio by gender and race/ethnicity groups and assess for potential additive and multiplicative interaction. Overall, women had lower prevalence of CVD risk factors than men, with less hypertension (p = 0.040), lower triglycerides (p < 0.001), higher HDL (p < 0.001), and a greater likelihood of a heart healthy lifestyle, more likely not to smoke and to follow a healthy diet (p < 0.05). When further stratified by race/ethnicity, however, the female advantage was largely restricted to non-Latino white women. Non-Latino black women had significantly higher risk of being overweight or obese, having hypertension, and having diabetes than non-Latino white men or women, or than non-Latino black men (p < 0.05). Non-Latino black women also had higher total cholesterol compared to non-Latino black men (184.4 vs 170.5 mg/dL, p = 0.010). Despite efforts to improve cardiovascular health and narrow disparities, non-Latino black women continue to have a higher burden of CVD risk factors than other gender and racial/ethnic groups. This study highlights the importance of assessing for intersectionality between gender and race/ethnicity groups when examining CVD risk factors.

Diets Rich in Fruits and Vegetables Are Associated with Lower Cardiovascular Disease Risk in Adolescents

Obesity and cardiovascular disease (CVD) risk are public health concerns in adolescents, yet few studies have examined the association of their diet to CVD risk factors. This study investigated associations between diet, body mass index (BMI), waist circumference (WC), blood pressure (BP), and blood lipids in 163 16-17 year olds. Diet recall data were converted into Healthy Eating Index-2010 (HEI) to assess diet quality. Differences in diet between groups with normal or obese BMI, normal or hypertensive BP, and normal or altered lipids were determined. Associations between diet and BMI, WC, BP, and lipids, controlling for race, gender, and socioeconomic status, were examined. Mean HEI was 49.2 (±12.0), with no differences observed between groups. HEI was not associated with any CVD risk. Sweetened beverage consumption was higher in obese adolescents, and positively related to total cholesterol (TC). Fruit intake was negatively related to BMI and diastolic BP. Total vegetable intake was negatively related to systolic BP. Greens and beans were negatively related to TC and LDL. Whole grains were negatively related to HDL. This research suggests a cardioprotective effect of diets rich in fruits and vegetables, as well as low in sweetened beverages in adolescents.

Heterogeneity in Blood Pressure Transitions Over the Life Course: Age-Specific Emergence of Racial/Ethnic and Sex Disparities in the United States

Importance

Many studies have assessed racial/ethnic and sex disparities in the prevalence of elevated blood pressure (BP) from childhood to adulthood, yet few have examined differences in age-specific transitions between categories of BP over the life course in contemporary, multiracial/multiethnic populations.

Objective

To estimate age, racial/ethnic, and sex-specific annual net transition probabilities between categories of BP using Markov modeling of cross-sectional data from the National Health and Nutrition Examination Survey.

Design, Setting, and Participants

National probability sample (National Health and Nutrition Examination Survey in 2007-2008, 2009-2010, and 2011-2012) of 17 747 African American, white American, and Mexican American participants aged 8 to 80 years. The data were analyzed from September 2014 to November 2015.

Main Outcomes and Measures

Age-specific American Heart Association-defined BP categories.

Results

Three National Health and Nutrition Examination Survey cross-sectional samples were used to characterize the ages at which self-reported African American (n = 4973), white American (n = 8886), and Mexican American (n = 3888) populations transitioned between ideal BP, prehypertension, and hypertension across the life course. At age 8 years, disparities in the prevalence of ideal BP were observed, with the prevalence being lower among boys (86.6%-88.8%) compared with girls (93.0%-96.3%). From ages 8 to 30 years, annual net transition probabilities from ideal to prehypertension among male individuals were more than 2 times the net transition probabilities of their female counterparts. The largest net transition probabilities for ages 8 to 30 years occurred in African American young men, among whom a net 2.9% (95% CI, 2.3%-3.4%) of those with ideal BP transitioned to prehypertension 1 year later. Mexican American young women aged 8 to 30 years experienced the lowest ideal to prehypertension net transition probabilities (0.6%; 95% CI, 0.3%-0.8%). After age 40 years, ideal to prehypertension net transition probabilities stabilized or decreased (range, 3.0%-4.5%) for men, whereas net transition probabilities for women increased rapidly (range, 2.6%-13.0%). Mexican American women exhibited the largest ideal to prehypertension net transition probabilities after age 60 years. The largest prehypertension to hypertension net transition probabilities occurred at young ages in boys of white race/ethnicity and African Americans, approximately age 8 years and age 25 years, respectively, while net transition probabilities for white women and Mexican Americans increased over the life course.

Conclusions and Relevance

Heterogeneity in net transition probabilities from ideal BP emerge during childhood, with associated rapid declines in ideal BP observed in boys and African Americans, thus introducing disparities. Primordial prevention beginning in childhood and into early adulthood is necessary to preempt the development of prehypertension and hypertension, as well as associated racial/ethnic and sex disparities.

THE RELATIONSHIPS AMONG VIGILANT COPING STYLE, RACE, AND DEPRESSION

Although Black-white differences in depression are well documented, vigilant coping style as an explanation for the observed inequalities in depression is less understood. Using data from 718 adults in the Exploring Health Disparities in Integrated Communities (EHDIC) Study, we estimated logistic regression models to examine the cross sectional relationship between race, vigilant coping style, and depression. After controlling for demographic variables, white adults were more likely to report depression than Black adults. Moreover, when accounting for coping style, the Black-white difference in depression widened. This association persisted even with the addition of the covariates. While high rates of depression among whites compared with Blacks are well documented, the degree of the differences appears to be greater than previously reported once vigilance is accounted for. This finding suggests that if it were not for the high prevalence of vigilant coping in blacks, the well-documented black advantage regarding depression compared to whites would likely be even greater.

Interactive influences of ethnicity, endothelin-1 gene, and everyday discrimination upon nocturnal ambulatory blood pressure

BACKGROUND

Everyday discrimination scale scores are associated with increased ambulatory blood pressure (BP) and reduced nocturnal dipping, and the endothelin-1 (ET-1)/Lys198Asn polymorphism is associated with increased resting BP and exaggerated BP reactivity among African Americans compared to European Americans. Combined influences of these factors on BP control are unknown.

PURPOSE

This study tested the hypothesis of a three-way interaction between ethnicity, ET-1 carrier status, and everyday discrimination upon ambulatory BP and nocturnal dipping.

METHODS

Baseline laboratory anthropometrics and the everyday discrimination scale were completed by 352 (175 African American) young adult normotensives, followed by 24-h ambulatory BP monitoring.

RESULTS

For nocturnal dipping, multiple regression models controlling for age, sex, ethnicity, and body mass index revealed significant three-way ET-1 × everyday discrimination × ethnicity interactions. Specifically, among African American ET-1 T-allele carriers, increases in everyday discrimination led to reduced nocturnal dipping.

CONCLUSIONS

African Americans that carry the ET-1/Lys198Asn T-allele and report higher everyday discrimination scores may be at particular risk for reduced nocturnal dipping.

Recent trends in healthcare utilization among children and adolescents with hypertension in the United States

The objective of this study was to evaluate the healthcare utilization of hospitalized children with hypertension. The Healthcare Cost and Utilization Project Kids' Inpatient Database, years 1997, 2000, 2003, and 2006, was used to identify hypertension hospitalizations. We examined the association of patient and hospital characteristics on hypertension charges. Data from each cohort year were used to analyze trends in charges. We found that 71282 pediatric hypertension hospitalizations generated $3.1 billion in total charges from 1997 to 2006. Approximately 68% were 10 to 18 years old, 55% were boys, and 47% were white. Six percent of claims with a diagnosis code for hypertension also had a diagnosis code for end-stage renal disease or renal transplant. The frequency of hypertension discharges increased over time (P=0.02 for each of age groups 2-9 years and 2-18 years; P=0.03 for age group 10-18 years), as well as the fraction of inpatient charges attributed to hypertension (P<0.0001). Length of stay and end-stage renal disease were associated with increases in hospitalization associated charges (P<0.0001 and P=0.03, respectively). During the 10-year study period, the frequency of hypertension-associated hospitalizations was increasing across all of the age groups, and the fraction of charges related to hypertension was also increasing. The coexisting condition of end-stage renal disease resulted in a significant increase in healthcare charges.

Blood pressure variability, prehypertension, and hypertension in adolescents

Medical conditions diagnosed during adolescence may have long term impacts on the health of an individual. As a result, identifying cardiovascular risk factors earlier in life such as prehypertension (pre-HTN) and hypertension (HTN) can have significant benefits across an individual’s lifespan. Diagnosing elevated blood pressure (BP) during adolescence can be difficult, partially due to the natural variability that occurs during this period of life. Levels of BP that define adolescent prehypertension/hypertension are provided as well as an abridged review of BP variability across research groups. Strategies for BP management of adolescents are considered, with the primary focus on nonpharmacologic interventions.

Blood pressure and obesity among adolescents: a school-based population study in China

BACKGROUND

There is little information regarding the obesity epidemical situation and risk factors of childhood hypertension (HTN) in China. The present study aimed to determine the prevalence of HTN/prehypertension (PHTN), as well as the associated risk factors, among adolescents in Changsha city, China.

METHODS

A total of 88,974 adolescents from 49 middle schools in Changsha city between 12 and 17 years of age were examined during 2009. Body weight, height, and blood pressure (BP) were measured in all adolescents. HTN and PHTN were defined according to sex- and age-specific Chinese reference data. Overweight and obesity were also defined according to sex- and age-specific Chinese reference data.

RESULTS

It was determined that the prevalence of PHTN and HTN were 7.2 and 3.1%, respectively. Furthermore, 14.6% of male adolescents were overweight and 7.0% were obese, whereas 8.6% of female adolescents were overweight and 2.9% were obese. The risk ratio (RR) of HTN were significantly higher in overweight (RR: 2.8, 95% confidence interval (CI): 2.6-3.2) and obese (RR: 8.7, 95% CI: 8.1-9.5) adolescents adjusted for age, sex, and height.

CONCLUSIONS

Chinese reference data were used to evaluate BP and body mass index (BMI) of children and adolescents. Higher prevalence of HTN was associated with higher BMI percentiles. Being overweight or obese markedly increased the risk of both HTN and PHTN among adolescents between 12 and 17 years of age in Changsha city, China.

Stimulus response of blood pressure in black and white young individuals helps explain racial divergence in adult cardiovascular disease: the Bogalusa Heart Study

Blood pressure (BP) is a highly variable physiologic trait with short-term and long-term fluctuations within the same individual at different time points. The burden of BP on the cardiovascular (CV) system has been studied in terms of multiple cross-sectional BP measurements at rest, response of BP to stresses, and long-term longitudinal variability of BP. Observations from childhood are available extending into early middle age in the biracial (black-white) population of Bogalusa, Louisiana. Left ventricular mass index was used to illustrate damaging effects on the CV system by both resting BP levels and fluctuations. Long-term BP variability reflecting intermittent and repeated variability was shown to have a greater effect in blacks. The childhood BP response to several stressors was found to be greater in blacks. These observations suggest that, although at rest a greater vagal effect occurs in blacks, they show a greater response when reacting to a stimulus. This, along with aspects such as carbohydrate-insulin metabolism or other biochemical/physiological differences, may account for the greater acceleration of CV atherosclerosis in blacks. The racial contrasts suggest, in part, that effects of lipoproteins may be greater in whites, whereas the effects of excess BP levels and variability of BP and Na(+)-K(+) intake and diet as well as other environmental effects result in more CV damage in blacks. The strong association of hemodynamic measures with anatomic, metabolic, and environmental factors emphasizes the need to begin prevention of risk factors at an early age. Taken together, understanding racial (black-white) contrasts to stress contribute to both prevention and treatment of hypertension, especially for black males.

Genetic influences on daytime and night-time blood pressure: similarities and differences

OBJECTIVE

To examine whether the genetic influences on blood pressure (BP) during night-time are different from those during daytime and the extent to which they depend on ethnicity or sex.

METHODS

Ambulatory BP was measured in 240 European-American and 190 African-American twins (mean +/- SD age, 17.2 +/- 3.4). Individuals with night-time BP falls more than 10% of the daytime values were defined as dippers. A bivariate analysis of the daytime and the night-time BP levels, as well as a liability-threshold model of dippers vs. nondippers were used.

RESULTS

Bivariate model fitting showed no ethnic or sex differences for any of the measures, with heritabilities of 0.70 and 0.68 for SBP and 0.70 and 0.64 for DBP at daytime and at night-time. The genetic influences on daytime and night-time were not significantly different for SBP or DBP. The bivariate analysis also indicated that about 56 and 33% of the heritabilities of night-time SBP and DBP could be attributed to genes that also influenced daytime levels. The specific heritabilities due to genetic effects only influencing night-time values were 0.30 for SBP and 0.43 for DBP. The heritabilities of systolic and diastolic dipping were 0.59 and 0.81, respectively.

CONCLUSION

Independent of ethnicity and sex, an overlap exists between genes that influence daytime and night-time BP, as well as a significant genetic component that is specific to the night-time BP. These findings suggest that different genes or sets of genes contribute to BP regulation at daytime and night-time.

Relationship between waking-sleep blood pressure and catecholamine changes in African-American and European-American women

BACKGROUND

A blunted decline in waking to sleep blood pressure (BP) is more common in African-American (AA) than European-American (EA) women. The causes of reduced BP 'dipping' in AA women are not known, although several factors including ethnic differences in catecholamine sensitivity have been suggested. The purpose of this study was to investigate the possible contribution of catecholamine influences on BP to ethnic differences in BP dipping in a sample of working women.

PARTICIPANTS AND METHODS

Healthy female participants wore ambulatory BP monitors over the course of 1 work day and night. Urine samples for assay of epinephrine and norepinephrine were collected at work (approximately 11.00-15.00 h), home (approximately 06.00-22.00 h) and during sleep (approximately 22.00-06.00 h). Analysis of covariance was used to assess the relationships between changes in BP and the catecholamines by ethnicity.

RESULTS

AA women (n=51; age=38.9+/-8.5 years) had smaller proportional BP changes from work to sleep and home to sleep than EA women (n=110; age=37.1+/-9.2 years). Overall, the work to sleep change in epinephrine excretion was positively associated with changes in both SBP (P<0.003) and DBP (P<0.001); however, there was an ethnic difference in the epinephrine-BP relationship. For AA women, these associations were highly positive and significant, but for EA women, there was little correlation. Nonetheless, the analysis also revealed that overall, the work to sleep BP changes were not directly related to ethnic differences in catecholamine variation.

CONCLUSION

The AA-EA difference in waking-sleep BP changes (dipping) is not directly related to ethnic differences in catecholamine variation; however, AA seem to have a greater BP sensitivity to epinephrine.

The effects of nocturnal dipping on cardiovascular outcomes and proteinuria in essential hypertensive patients

Individuals who do not have a 10% to 20% reduction in blood pressure (BP) during the night are known as ‘nondippers’. Non-dipping patterns in hypertensive patients have been shown to be associated with an excess of target organ damage and other adverse outcomes. The present study was designed to investigate the relationship between nocturnal BP pattern, defined on the basis of the ambulatory blood pressure monitoring (ABPM) recording, and cardiac and renal target organ damage in a population of at least one year treated essential hypertensive subjects. The present analysis involved 123 patients with treated essential hypertension attending the outpatient clinic of our centre. Each patient was subjected to the following procedures: blood sampling for routine blood chemistry, spot urine for proteinuria, 24-hour periods of ABPM, and echocardiography. In the ABPM period, a dipping pattern was observed in 65 of the 123 patients, and a non-dipping pattern in 58 patients. Body mass index was higher in the non-dippers (26 ± 4 versus 28 ± 4, p<0.05). The proteinuria in spot urine was significantly higher in the non-dippers (10 ± 6 versus 24 ± 48, p<0.03). Left ventricular mass, interventricular septum thickness, posterior wall thickness and left ventricular systolic diameter were significantly higher in the non-dippers compared to the dippers. Left ventricular diastolic function was similar in non-dipper cases, except E-wave deceleration time. In treated essential hypertensives the blunted or absent nocturnal fall in blood pressure can be a strong predictor of cardiac and renal events. Hypertensive patients should be evaluated by ambulatory blood pressure monitoring. To prevent patients at risk for morbidity and mortality casualities as a result of hypertension, patients should be evaluated by ambulatory blood pressure monitoring. This method can be utilized for exacting future follow-ups with the patient.

Impact of myocardial geometry on left ventricular performance in healthy black and white young adults

Racial differences in left ventricular (LV) structure are suggested by clinical and experimental studies. This study evaluates if racial differences in LV performance exist comparing black to white young males, by tissue Doppler echocardiography and myocardial performance index (MPI). We examined 40 healthy males, 20 blacks (mean age 27.6 +/- 4.4 years) and 20 whites (mean age 26.5 +/- 6.7 years). All subjects underwent conventional echocardiography, tissue Doppler echocardiography, and MPI assessment. No differences were found in LV diameters, volumes, mass, and hemodynamic measurements. Septal and posterior wall thicknesses were significantly increased in black subjects as well as the relative wall thickness. Systolic and diastolic functions estimated by conventional parameters were superimposable in the two groups. In black subjects, a significant increase of septal S-wave, peak velocity, and time-velocity integral were found. MPI was significantly higher in black compared to white subjects (0.46 +/- 0.05 vs 0.40 +/- 0.06, P < 0.002). A significant correlation between MPI and relative wall thickness (r = 0.54) was demonstrated. Besides, MPI correlated with S(pv) (r = 0.55) and S(tvi) (r = 0.38) at the septal site. In conclusion our data show a higher MPI in black subjects that seems to be geometry-dependent. Correlations between MPI and tissue Doppler echocardiography systolic indexes were found. Our findings suggest that racial differences in LV performance exist, especially, in the systolic function, even in the absence of other conventional echocardiographic changes.

Cardiac hypertrophy: mechanisms and therapeutic opportunities

Cardiac hypertrophy and heart failure are major causes of morbidity and mortality in Western societies. Many factors have been implicated in cardiac remodeling, including alterations in gene expression in myocytes, cardiomyocytes apoptosis, cytokines and growth factors that influence cardiac dynamics, and deficits in energy metabolism as well as alterations in cardiac extracellular matrix composition. Many therapeutic means have been shown to prevent or reverse cardiac hypertrophy. New concepts for characterizing the pathophysiology of cardiac hypertrophy have been drawn from various aspects, including medical therapy and gene therapy, or use of stem cells for tissue regeneration. In this review, we focus on various types of cardiac hypertrophy, defining the causes of hypertrophy, describing available animal models of hypertrophy, discussing the mechanisms for development of hypertrophy and its transition to heart failure, and presenting the potential use of novel promising therapeutic strategies derived from new advances in basic scientific research.

Ethnic and Gender Differences in Ambulatory Blood Pressure Trajectories

Background— Cross-sectional studies demonstrated ethnic and gender differences in ambulatory blood pressure patterns, but little is known about the longitudinal development of these differences.

Methods and Results— Twenty-four-hour ambulatory blood pressure was measured up to 12 times (5 times on average) over a 15-year period in 312 African Americans (AAs) and 351 European Americans aged 7 to 30 years. Multivariate individual growth curves across age were created for daytime and nighttime blood pressure jointly. For both daytime and nighttime systolic blood pressure (SBP), AAs and males had higher levels ( P <0.001) than European Americans and females. Males also showed a greater increase with age ( P <0.001) than females. For nighttime SBP, a faster increase of SBP with age ( P <0.01) in AAs was additionally observed. The ethnic difference in nighttime SBP levels and its increase with age were significantly larger than in daytime SBP. For daytime and nighttime diastolic blood pressure, AAs had higher levels than European Americans ( P <0.001), and this difference was significantly larger at night. From late adolescence onward, males showed a greater increase in diastolic blood pressure with age than females. Ethnic and gender differences persisted after adjustment for height, body mass index, socioeconomic status, and stress-related coping styles. Family history of essential hypertension explained ethnic differences in daytime SBP.

Conclusions— We observed significant ethnic and gender differences in longitudinal trajectories of ambulatory blood pressure in youth and young adults. The blunted nocturnal decline and its exacerbation with age in AAs corroborate and extend findings of cross-sectional studies.

Abnormal blood pressure circadian rhythm: a target organ damage?

Blood pressure (BP) varies according to cycles characterized by a reduction during sleep and an increase on awakening. The nighttime decrease is absent or blunted in some patients (termed "non-dippers"). Cross-sectional and prospective data have shown that non-dippers have more target organ damage than have dippers in normotensive and hypertensive subjects. We reviewed the English language literature regarding this association. A non-fortuitous association seems to exist between non-dipper status and cardiovascular risk such as stroke and cardiac events. Among diabetic patients, this phenomenon has been described to occur more often in individuals with autonomic neuropathy and with different degrees of diabetic nephropathy. In normoalbuminuric normotensive type I diabetic patients without any degree of autonomic dysfunction, according to traditional cardiovascular tests, diastolic BP (dBP) night/day ratio is associated with an increased glomerular filtration rate and an increased extracellular volume. The disruption of the circadian rhythm of sympathovagal activity in non-dipper patients was associated with higher levels in systolic BP (sBP) and dBP and with a reduced decline in sBP and dBP levels during the night. Therefore, the prognostic implications of the non-dipper status may be important since the overall 24-h blood pressure load is elevated in these individuals. These data suggest that patients in whom blood pressure decreases during the night incur less damage to their brain, kidneys, heart, and blood vessels than people with elevated nocturnal BP.

Occupational differences in job strain and physiological stress: female nurses and school teachers in Hawaii

OBJECTIVES

The two objectives are to test the hypothesis that women in a profession with low decision latitude will have greater catecholamine excretion and higher blood pressure than women in a profession with greater decision latitude, and to assess the influence of ethnicity on the occupational comparison.

METHODS

Premenopausal women who were either full-time teachers in public schools (teachers; N = 92) or nurses or nurse's aides (nurses; N = 55) in East Hawaii who were not currently taking antihypertensive medication had ambulatory blood pressure (BP) and urinary catecholamine excretion measured over an approximate 4-hour period at work and home and over an approximate 8-hour period overnight. The women also filled out the Job Content Questionnaire (JCQ).

RESULTS

The nurses had significantly lower scores on the "decision latitude" subscale of the JCQ. After controlling for the effects of ethnicity, age, body mass index, JCQ subscale scores, smoking habits, and menopausal status in regression analyses, the nurses also had significantly higher mean systolic and diastolic BP both in work and home settings and higher mean rates of both norepinephrine and epinephrine excretion in all daily settings (p < .05). There were no significant ethnic differences in scores on the JCQ subscales, but Asian-Americans had significantly higher systolic BP in all daily settings and higher diastolic BP overnight (p < .05) than Euro-Americans.

CONCLUSIONS

These results suggest that among professional women, physiological stress responses are significantly greater when occupation-related decision latitude is low (nurses) than when it is high (teachers). The physiological response to stress is carried over into the home and overnight settings when occupation-related decision latitude is low (nurses). Individual scores on the JCQ were not significantly related to physiological measures in this study, however. Inclusion of contrasting occupations may be necessary to properly evaluate the relationships between individually reported job strain and heightened physiological stress responses in studies of working women.

Pathophysiology of Antihypertensive Therapy with Diuretics

Recent progress in antihypertensive therapy has widened the selection of drugs, and large clinical trials have attracted attention to newer classes of antihypertensives. Consequently, the use of diuretics as antihypertensive agents has been relatively reduced, particularly since the newer drugs are associated with fewer adverse metabolic reactions. However, diuretics have a specific activity of removing sodium from the body fluid, thereby rendering the blood pressure insensitive to sodium intake, relieving the overload to systemic circulation, and normalizing the circadian rhythm of blood pressure from a non-dipper to a dipper pattern. At low doses, diuretics are known to be as effective as all other antihypertensive agents for reducing nearly all types of cardiovascular events. In this brief review, the indication for thiazide diuretics will be discussed based on the pathophysiology of hypertension and antihypertensive therapy with diuretics mainly from the point of view of sodium metabolism. Low-dose diuretics will continue to be an important agent in the treatment of hypertension, mostly in combination with vasodilators such as modulators of the reninangiotensin system and calcium channel blockers.

A prospective assessment of myocardial contractility in young African Americans: does ethnicity impact the wall stress-heart rate-corrected velocity of circumferential fiber shortening relationship?

BACKGROUND

The end-systolic wall stress (ESS)-heart rate-corrected velocity of circumferential fiber shortening (VCFc) relationship provides a load-independent assessment of systolic function. Previously published indices may not be appropriate for studies where ethnicity may introduce bias.

OBJECTIVE

We sought to investigate potential differences in the ESS-VCFc relationship between the African American (AA) and Caucasian population.

METHODS

In all, 50 AAs and 72 Caucasians, age 3 months to 17 years, were studied. Arterial pulse tracing, phonocardiogram, electrocardiogram, and M-mode of the left ventricle were recorded. Left ventricular dimensions, functional indices, ESS, and ESS-VCFc relationships were compared between groups.

RESULTS

AAs had decreased indexed left ventricular end-systolic dimensions and increased septal and posterior wall thickness. AAs had increased percent fractional shortening, VCFc, and decreased ESS. Meridional ESS-VCFc relationships for the groups were similar.

CONCLUSIONS

Young AAs have slightly thicker ventricles with increased VCFc, lower systolic volumes, and diminished ESS compared with control subjects. Despite differences, the meridional ESS-VCFc relationships were similar and correlated closely to previously reported normal indices.

The change in blood pressure during pubertal growth

Blood pressure (BP) in children may increase more during puberty. Using a cohort of children where BP and body size had been closely monitored, we compared the rates of change in BP during the 3-yr period before puberty, during puberty ( approximately 4.5-yr period), and the 3-yr period after puberty. Because there was no specific staging information with respect to puberty, we used pubertal growth (PG) as a surrogate of puberty. The latter was determined from serial measurements of height. All subjects (n = 151) were followed from before the period of PG to the period after PG; none were related. An age-dependent increase in systolic BP in the pre-PG period was similar regardless of sex or race. During PG, systolic BP in males increased three to six times faster than in the pre-PG period. In females, systolic BP increased less than in males during PG but still increased two to four times faster than in the pre-PG period. The increase in males was significantly greater than in females (P < 0.001). Post-PG changes in BP were similar to changes in pre-PG BP. In summary, PG was associated with profound increases in systolic BP. There were noticeably greater increments in males than in females consistent with the emergence of the well known sexual dimorphism in BP.

Temporal stability of twenty-four-hour ambulatory hemodynamic bioimpedance measures in African American adolescents

BACKGROUND

The reliability of ambulatory impedance cardiography has not been evaluated.

OBJECTIVE

The purpose of this study was to determine the reproducibility of daytime and night-time ambulatory bioimpedance-derived measures of hemodynamic function in youth.

METHODS

Thirty-five African American adolescents (ages 16.2+/-1.4 years, 14 girls, 21 boys) with high normal systolic resting blood pressure (BP) were evaluated twice, separated by a 2-month interval. Measures were collected using the AIM-8-V3 Wearable Cardiac Performance Monitor (Bio-impedance Technology, Inc., Chapel Hill, North Carolina, USA) and the Spacelabs ambulatory BP monitor 90207 (Spacelabs Inc., Redmond, Washington, USA) from 0600 h to midnight every 20 min and from midnight to 0600 h every 30 min in the natural environment.

RESULTS

There were no significantly different means (P>0.15) between the two visits for daytime ambulatory heart rate (HR, r = 0.81), stroke volume (SV, r = 0.54), cardiac output (CO, r = 0.56), pre-ejection period (PEP, r = 0.59), left ventricular ejection time (LVET, r = 0.74), Heather Index (HI, r = 0.79), systolic BP (SBP, r = 0.79), diastolic BP (DBP, r = 0.66), mean arterial pressure (MAP, r = 0.65) and total peripheral resistance (TPR, r = 0.47). Overall means for night-time ambulatory HR (r = 0.76), SV (r = 0.49), CO (r = 0.45), LVET (r = 0.43), HI (r = 0.82), SBP (r = 0.65), DBP (r = 0.62), MAP (r = 0.63) and TPR (r = 0.20) were not significantly different between visits (P > 0.06). Mean differences (P < 0.01) were observed for PEP (r = 0.57).

CONCLUSIONS

The findings demonstrate that across 2 months in youth daytime and night-time ambulatory bioimpedance-derived measures of HR, HI, SBP, DBP and MAP are highly repeatable and SV, CO, PEP and LVET are moderately repeatable. This methodology should prove useful in cardiovascular research and clinical care.

Heart failure-the importance of ethnicity

Heart failure is a major public health problem in the Western world. Aetiological factors involved in its development include hypertension, diabetes, and ischaemic heart disease--all of which differ in prevalence, and possibly mechanism, between patients of differing ethnicity. Unfortunately, epidemiological and therapeutic trials have involved almost exclusively white populations, and evidence from these trials cannot necessarily be assumed to be generalisable to populations that include high proportions of patients from other ethnic origins. This review will discuss the mechanistic and therapeutic differences that exist in heart failure between those of European origin, and patients from the major ethnic minority groups of the UK.

A comparison of awake???sleep blood pressure variation between normotensive Japanese???American and Caucasian Women in Hawaii

OBJECTIVE

To compare awake-sleep ambulatory blood pressure variation between Japanese-American and Caucasian women in Hawaii, specifically determining whether Japanese-Americans have reduced dipping of blood pressure during sleep, as is found in comparisons of Japanese and US samples.

METHODS

Normotensive school teachers from East Hawaii who were either of Japanese-American (n = 70) or Caucasian (n = 48) ethnicity were recruited. They wore an ambulatory blood pressure monitor (Spacelabs 90207) that took measurements every 15 min during waking hours and every 30 min during sleep for a 24-h period on a normal workday. All subjects provided demographic information and underwent a series of anthropometric measurements the day before monitoring. Japanese-American subjects also answered questionnaires relating to cultural identity and migration history.

RESULTS

The Japanese-American women had significantly higher mean diastolic (P < 0.01) blood pressure during sleep. These ethnic differences in sleep blood pressure persisted when analyses controlled for age, body mass index, and the waist-hip circumference ratio. There were also significant differences in the proportion by which blood pressure dipped from waking to sleeping, with the Japanese-American women dipping significantly less than the Caucasian women (P < 0.05 systolic, P < 0.001 diastolic).

CONCLUSIONS

Normotensive Japanese-American women have higher sleep pressure, and a smaller awake-sleep dip, in pressure than Caucasian women. The relative elevation of blood pressure in Japanese-American women during sleep, but not at other times of the day, is similar to the pattern seen among Japanese women in Japan.

The effect of race and sleep-disordered breathing on nocturnal BP "dipping": analysis in an older population

STUDY OBJECTIVES

BP normally drops (or "dips") by approximately 10% at nighttime; however, in a number of illnesses there is an increased amount of "nondipping" of nocturnal BP. This study examined whether nondipping in older African Americans and older white subjects is related to the presence of sleep-disordered breathing (SDB) and hypertension.

DESIGN

Prospective study with a convenience sample.

SETTING

All data were collected in the subjects' homes.

PARTICIPANTS

Seventy self-defined African Americans with complaints of snoring or excessive daytime sleepiness, and 70 age-matched and gender-matched white subjects.

MEASUREMENTS AND RESULTS

Sleep was recorded for 2 nights, with 1 night of oximetry. BP was recorded on a separate 24-h period. African Americans had higher dipping ratios than white subjects even after accounting for covariates such as respiratory disturbance index (RDI), oxygen desaturation index (ODI), body mass index, and average 24-h mean arterial pressure (p = 0.025). Higher values of RDI (R(2) = 0.0686, p = 0.021) and ODI (R(2) = 0.042, p < 0.03) were correlated with higher dipping ratios in both African Americans and white subjects. However, there was a three-way interaction such that higher RDIs were correlated primarily with nondipping in African Americans receiving antihypertensive medication (R(2) = 0.0373, p = 0.022).

CONCLUSIONS

These results demonstrated that African Americans tend to be "nondippers," while white subjects tended to be "dippers." This nondipping was not a result of weight, gender, or of having SDB. The analyses also confirmed that, in both races, the dipping ratio was greatest in those with SDB and hypertension. The third hypothesis, that RDI would be greatest in the nondipping hypertensive subjects, was true only for the African Americans.

A comparison of ambulatory blood pressure patterns across populations

BACKGROUND

Black individuals are characterized by a blunted nocturnal decline (i.e. dipping) in blood pressure compared with whites. The resulting increase in cardiovascular load has been hypothesized to contribute to ethnic differences in hypertension and its sequelae.

OBJECTIVE

To examine data from two different locations and determine factors related to ethnic differences in ambulatory blood pressure pattern.

METHODS

Ambulatory blood pressure recordings were performed on 300 youths from Memphis, Tennessee and 195 youths from Augusta, Georgia, USA. Stepwise regressions were performed to determine the factors associated with daytime and night-time blood pressure and the nocturnal decline in blood pressure. The factors examined were recording location, ethnicity, gender, age, height, weight and genetic predisposition.

RESULTS

Significant factors in the model for the nocturnal decline in systolic blood pressure included location (R(2) = 0.031, P < 0.001), followed by ethnicity (R(2) change = 0.015, P < 0.006) and height (R(2) change = 0.009,P < 0.03). Significant factors in the model for the nocturnal decline in diastolic blood pressure included location ( R(2) = 0.176, P < 0.001), followed by ethnicity ( R(2) change = 0.016, P < 0.002) and height (R(2) change = 0.02, P < 0.001). The nocturnal decline was greater in the Augusta subjects because of higher daytime systolic (P < 0.002) and diastolic (P < 0.001) blood pressure. Weight contributed significantly to the models for resting blood pressure and daytime blood pressure. Gender was the only variable that contributed to the model for resting systolic blood pressure.

CONCLUSIONS

Both genetic and environmental factors contribute to individual differences in ambulatory blood pressure patterns. Much of the variance of ambulatory blood pressure levels and patterns remains, however, unexplained.

A longitudinal study of ethnic differences in ambulatory blood pressure patterns in youth

BACKGROUND

Many studies demonstrated an ethnic difference in ambulatory blood pressure (BP) patterns. We examined: 1) the stability of this difference; 2) demographic and anthropometric characteristics that predict the difference over 2 years; and 3) the clinical significance of the difference.

METHODS

Recordings were performed 2 years apart on 94 African American and 92 European American youths with a positive family history of hypertension, aged 14 +/- 2 years at initial testing.

RESULTS

African Americans had higher nighttime systolic BP (SBP) on the initial (109 +/- 9 v 105 +/- 8 mm Hg; P < .001) and follow-up (110 +/- 10 v 105 +/- 8 mm Hg; P < .0001) visits despite similar daytime SBP. This was associated with greater left ventricular mass/height2.7 (LVM/height2.7) during the initial (31 +/- 8 v 28 +/- 6 g/height2.7; P < .01) and follow-up (32 +/- 8 v 28 +/- 8 g/height2.7; P < .02) visits. Sex accounted for 17% (P < .0001) of the variance of follow-up daytime SBP in African Americans, and age for an additional 10% (P < .001). In comparison, initial height accounted for 11% (P < .001) of the variance in European Americans. Sex accounted for 18% (P < .0001) of the variance of follow-up nighttime SBP in African Americans, age for an additional 12% (P < .0001), and initial LVM/height2.7 an additional 6% (P < .02). In contrast, sex accounted for 13% of the variance of follow-up nighttime SBP in European Americans, and initial height accounted for an additional 8% (P < .004).

CONCLUSIONS

The pattern of higher nighttime BP despite similar daytime BP in African Americans is stable over time, with sex as the most important predictor of nighttime BP in both groups. This study provides confirmatory data on the clinical significance of the differences.

The relation between maternal work, ambulatory blood pressure, and pregnancy hypertension

STUDY OBJECTIVE

The purpose of the study was to determine the relations between maternal work, ambulatory blood pressure in mid-pregnancy, and subsequent pregnancy outcome.

DESIGN

Data were studied on 933 healthy normotensive primigravidas who had been enrolled into a study on the predictive value of ambulatory blood pressure measurement performed between 18 and 24 weeks gestation. They were classified into three groups depending on whether they were at work (working group, n=245), not working (not working group, n=289), or normally employed but chose not to work (ENK group, n=399), on the day monitoring was performed.

SETTING

The Rotunda Hospital (a large maternity hospital), Dublin, Ireland.

MAIN RESULTS

Adjusted for age, body mass index, smoking, drinking, and marital status, women at work had higher mean daytime systolic (p<0.01) and diastolic (p<0.01) and 24 hour systolic pressures (p=0.03) compared with those not working. The rate of subsequent development of pre-eclampsia was significantly higher (odds ratio 4.1, 95% CI 1.1 to 15.2, p=0.03) among those at work compared with those not working. The association between pre-eclampsia and maternal work remained significant (odds ratio 5.5, 95% CI 1.1 to 27.8, p=0.04) even after allowing for the confounding factors of age, smoking, body mass index, and marital status. When daytime systolic and diastolic blood pressure were added to the regression analysis the risk ratios for pre-eclampsia remained high but did not quite reach statistical significance (odds ratio 4.7, 0.90 to 24.8, p=0.066). Birth weight and placental weight were not predicted by work status or blood pressure.

CONCLUSIONS

A significant independent relation was found between maternal work and ambulatory blood pressure levels in mid-pregnancy. In addition, it was found that maternal work was significantly associated with the subsequent development of pre-eclampsia

Task Force II: blood pressure measurement and cardiovascular outcome

OBJECTIVE

To reach a consensus on the prognostic significance of new techniques of automated blood pressure measurement.

METHODS

A Task Force on the prognostic significance of ambulatory blood pressure monitoring wrote this review in preparation for the Eighth International Consensus Conference (28-31 October 2001, Sendai, Japan). This synopsis was amended to account for opinions aired at the conference and to reflect the common ground reached in the discussions.

POINTS OF CONSENSUS

(1) Prospective studies in treated and untreated hypertensive patients and in the general population have demonstrated that, even after adjusting for established risk factors, the incidence of cardiovascular events is correlated with blood pressure on conventional as well as ambulatory measurement. Ambulatory monitoring, however, significantly refines the prediction already provided by conventional blood pressure measurement. (2) White-coat hypertension is usually defined as an elevated clinic blood pressure in the presence of a normal daytime ambulatory blood pressure. Event-based studies in hypertensive patients have convincingly demonstrated that the risk of cardiovascular disease is less in patients with white-coat hypertension than in those with higher ambulatory blood pressure levels even after controlling for concomitant risk factors. Based on prognostic evidence, white-coat hypertension can now be defined as a conventional blood pressure that is persistently equal to or greater than 140/90 mmHg with an average daytime ambulatory blood pressure of below 135/85 mmHg. The issue of whether or not white-coat hypertension predisposes to sustained hypertension needs further research. (3) There is a growing body of evidence showing that a decreased nocturnal fall in blood pressure (<10% of the daytime level) is associated with a worse prognosis, irrespective of whether night-time dipping is studied as a continuous or a class variable. (4) Intermittent techniques of ambulatory blood pressure monitoring are limited in terms of quantifying short-term blood pressure variability. Proven cardiovascular risk factors such as old age, a higher than usual blood pressure and diabetes mellitus are often associated with greater short-term blood pressure variability. After adjusting for these risk factors, some - but not all - studies have nevertheless reported an independent and positive relationship between cardiovascular outcome and measures of variability of daytime and night-time blood pressure, for example standard deviation. (5) Reference values for ambulatory blood pressure measurement in children are currently based on statistical parameters of blood pressure distribution. In children and adolescents, functional rather than distribution-based definitions of ambulatory hypertension have yet to be developed. (6) Several studies of gestational hypertension have shown that, compared with office measurement, ambulatory blood pressure monitoring is a better predictor of maternal and fetal complications. Pregnancy is a special indication for ambulatory monitoring so that the white-coat effect can be measured and pregnant women are not given antihypertensive drugs unnecessarily. (7) Ambulatory pulse pressure and the QKD interval are measurements obtained by ambulatory monitoring that to some extent reflect the functional characteristics of the large arteries. The QKD interval is correlated with left ventricular mass, and ambulatory pulse pressure is a strong predictor of cardiovascular outcome. (8) Under standardized conditions, the self-measurement of blood pressure is equally as effective as ambulatory blood pressure monitoring in identifying the white-coat effect, but further studies are required to elucidate fully the prognostic accuracy of self-measured blood pressure in comparison with conventional and ambulatory blood pressure measurement.

CONCLUSIONS

Ambulatory blood pressure measurement refines the prognostic information provided by conventional blood pressure readings obtained in the clinic or the doctor's office. Longitudinal studies of patients with white-coat hypertension should clarify the transient, persistent or progressive nature of this condition, particularly in paediatric patients, in whom white-coat hypertension may be a harbinger of sustained hypertension and target-organ damage in adulthood. Finally, the applicability, cost-effectiveness and long-term prognostic accuracy of the self-measurement of blood pressure should be evaluated in relation to conventional blood pressure measurement and ambulatory monitoring.

Overview of ambulatory blood pressure monitoring in childhood and pregnancy

Despite the fact that the study and applicability of ambulatory blood pressure in children and pregnant women share characteristics which limit the potential development of knowledge for their use, advances produced in the last few years provided the present knowledge regarding the significance and the potential use of ambulatory blood pressure in children and in the pregnant women. In children ambulatory blood pressure monitoring is useful for the diagnosis of mild hypertensives, assessment of refractory hypertension, therapeutic trials with antihypertensive drugs, and clinical investigation when BP is one of the parameters to be taken into account and/or when subtle BP abnormalities are the objective of the study. In pregnant women, the main applicability is to assess the maternal and fetal risk in the hypertensive disorders of pregnancy.

Prevention of essential hypertension in minority populations

The precursors of essential hypertension (EH) begin in childhood. If the etiology of the evolution of EH were discovered, interventions may be developed to lead to the primary prevention of EH. In particular, one ethnic group, African-Americans (Blacks), are at increased risk of development of EH in adulthood. Hemodynamic changes in response to stressors are termed measures of cardiovascular reactivity (CVR). Ethnic difference in CVR are known to exist; are these markers or mechanisms of EH evolution? Investigations are underway to discover the mechanism(s) of the excessive vasoconstriction which appears to be characteristic of the CVR responses in Blacks. These may lead to the pharmacologic, or non-pharmacologic, interventions which may be initiated in childhood and prevent EH in adults.

Effects of antihypertensive agents on the left ventricle: clinical implications

Hypertensive heart disease (HHD) is characterized by left ventricular hypertrophy (LVH), alterations of cardiac function, and coronary flow abnormalities. LVH is an independent cardiovascular risk factor related to cardiovascular complications in patients with hypertension. Therefore, a decrease in left ventricular mass is a therapeutic goal in these patients. The effect of the different antihypertensive agents on LVH regression has been studied in nearly 500 clinical trials. Most studies conclude that there is regression of LVH after significant decrease in blood pressure with most commonly prescribed antihypertensive agents. However, the ability to regress LVH is different between antihypertensive drug classes. ACE inhibitors and calcium channel antagonists are more potent in reducing left ventricular mass than beta-blockers, with diuretics falling in the intermediate group. Recent data suggest that angiotensin AT(1) receptor antagonists reduce left ventricular mass to a similar extent as ACE inibitors or calcium channel antagonists. Although a large number of studies have established that reversal of LVH decreases the occurrence of adverse cardiovascular events in patients with hypertension, the hypothesis that LVH regression is beneficial has not yet been conclusively proven. On the other hand, the time has come to revisit the current management of HHD simply focused on controlling blood pressure and reducing left ventricular mass. In fact, it is necessary to develop new approaches aimed to repair myocardial structure and protect myocardial perfusion and function and, in doing so, to reduce in a more effective manner, adverse risk associated with HHD. The identification of genes involved in both the process of HHD and the response to therapy may be critical for the development of these new approaches. This article will review briefly the available data on the effects of antihypertensive agents on HHD. In addition, the emerging new concepts on the pharmacology of hypertensive myocardial remodeling and the pharmacogenetic basis of the treatment of HHD will be also considered.

A classification of circadian blood pressure profiles using a cumulative chi-square technique

Non-invasive ambulatory blood pressure monitoring has been used to assess circadian rhythms in blood pressure in a qualitative fashion. However, there are no established methods for assessing circadian changes in blood pressure in a quantitative fashion. In this study, we developed a quantitative method to evaluate the circadian rhythm based on profile analysis and a cumulative chi-square technique. This method was used to analyse the circadian blood pressure variations in 100 normotensive volunteers and 127 hypertensive patients. Three blood pressure profiles were identified for the normotensive group, while four were identified for the hypertensive group. Furthermore, there was a relationship between the discriminate blood pressure profiles and the severity of hypertension. We conclude that profile analysis of 24-h ambulatory blood pressure monitoring may be used to stratify patients with regard to the risk of complications of hypertension.

The association of blunted nocturnal blood pressure dip and stroke in a multiethnic population

Nondipping has been defined as a reduction in the mean systolic and diastolic blood pressure (BP) of <10% from awake to sleep. We hypothesized that nondipping might be associated with stroke in minority populations. We monitored BP over a 24 h period with an ambulatory device in 166 cases from a multiethnic population of stroke survivors (63 blacks, 61 non-Hispanic whites, and 42 Caribbean Hispanics, aged 69.5 +/- 11 years) and 217 community control subjects (73 blacks, 107 non-Hispanic whites, and 67 Caribbean Hispanics, aged 69 +/- 9 years). Prevalence of nondipping was significantly greater among cases than among control subjects (64% v. 37%, P < .001). In a multiple logistic regression model adjusted for traditional risk factors for stroke, nondipping conferred an increased risk for stroke. Probability of stroke associated with nondipping (odds ratio (OR) 2.5, confidence interval (CI) 1.6 to 4.0) was equal to that of traditional risk factors. Nondipping increased the chance of having a stroke in both non-Hispanic whites (OR 4.2, P < .001) and blacks/Caribbean Hispanics (OR 1.9, P = .03). The strength of the contribution of nondipping to stroke risk was similar in all ethnic groups. Nondipping was associated with stroke in both men and women. Given the previous reports that nondipping contributes to stroke risk in European and Asian populations, these data suggest that nondipping may be universally associated with risk for stroke.

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.

Diuretics shift circadian rhythm of blood pressure from nondipper to dipper in essential hypertension

BACKGROUND

Recently, we found that sodium restriction shifted the circadian rhythm of blood pressure from nondipper to dipper in patients with the sodium-sensitive essential hypertension. This study examined whether diuretics can transform the circadian rhythm of blood pressure from nondipper to dipper.

METHODS AND RESULTS

We studied 21 patients with essential hypertension during both a baseline period and a period of treatment with hydrochlorothiazide (25 mg daily). The periods lasted 4 weeks each. Twenty-four hour ambulatory blood pressures were measured on the same day of the week at the end of the each period. In nondippers (n=11), but not in dippers (n=10), a significant interaction existed between diuretic therapy and nocturnal fall in systolic and diastolic blood pressure, which indicated that the degree of nocturnal blood pressure fall was affected by diuretic therapy. Nocturnal fall, which was diminished in nondippers, was restored by diuretic therapy with hydrochlorothiazide, indicating that the circadian rhythm of blood pressure shifted from nondipper to dipper patterns.

CONCLUSIONS

The present study demonstrated that diuretics can restore nocturnal blood pressure decline in a manner similar to sodium restriction, which suggests that the kidneys and sodium metabolism may play important roles in the genesis of the circadian rhythm of blood pressure. Diuretic-based treatment may have an additional therapeutic advantage of reducing the risk for cardiovascular complications by transforming the circadian rhythm of blood pressure.

Effects of potassium on blood pressure in salt-sensitive and salt-resistant black adolescents

This study examined the effects of increasing dietary potassium on ambulatory blood pressure nondipping status (<10% decrease in blood pressure from awake to asleep) and cardiovascular reactivity in salt-sensitive and salt-resistant black adolescents. A sample of 58 normotensive (blood pressure, 101/57+/-9/4 mm Hg) black adolescents (aged 13 to 16 years) participated in a 5-day low sodium diet (50 mmol/24 h) followed by a 10-day high sodium diet (150 mmol/24 h NaCl supplement) to determine salt-sensitivity status. Participants showed a significant increase in urinary sodium excretion (24+/-19 to 224+/-65 mmol/24 h) and were identified as salt-sensitive if their mean blood pressure increase was >/=5 mm Hg from the low to high sodium diet. Sixteen salt-sensitive and 42 salt-resistant subjects were then randomly assigned to either a 3-week high potassium diet (80 mmol/24 h) or usual diet control group. Urinary potassium excretion significantly increased in the treatment group (35+/-7 to 57+/-21 mmol/24 h). At baseline, a significantly greater percentage of salt-sensitive (44%) compared with salt-resistant (7%) subjects were nondippers on the basis of diastolic blood pressure classifications (P<0.04). After the dietary intervention, all of the salt-sensitive subjects in the high potassium group achieved dipper status as a result of a drop in nocturnal diastolic blood pressure (daytime, 69 versus 67 mm Hg; nighttime, 69 versus 57 mm Hg). No significant group differences in cardiovascular reactivity were observed. These results suggest that a positive relationship between dietary potassium intake and blood pressure modulation can still exist even when daytime blood pressure is unchanged by a high potassium diet.

Significance of sympathetic nervous system in sodium-induced nocturnal hypertension

OBJECTIVE

The purpose of this study was to investigate the effects of salt loading on circadian patterns of blood pressure (BP) and sympathetic nervous activity.

SUBJECTS AND METHODS

Seventy-six patients with essential hypertension were hospitalized and placed on a low-salt diet (2 g/day) for 7 days followed by a high-salt diet (20-23 g/day) for another 7 days. On the last day of each salt diet, 24 h ambulatory BP, plasma noradrenaline concentrations, urinary noradrenaline excretion, plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured. Patients whose average mean BP was increased by more than 10% by salt loading were assigned to the salt-sensitive (SS) group (n = 44); the remaining patients, whose mean BP was increased by less than 10%, were assigned to the non-salt-sensitive (NSS) group (n = 32).

RESULTS

Salt loading converted the circadian pattern of BP from dippers, whose mean BP during the night-time was decreased by more than 10% from the daytime BP, to non-dippers in the SS group but not in the NSS group. A nocturnal decrease in plasma noradrenaline concentration was unaffected after salt loading in the NSS group but dampened in the SS group. The night-time/daytime ratio of urinary noradrenaline excretion, which was increased after salt loading in the SS group only, was greater in the SS group than in the NSS group under the high-salt diet. The salt-induced suppression rate of PRA and PAC was similar between the SS and NSS groups.

CONCLUSION

BP fails to fall during the night under the high-salt diet in patients with the SS type of essential hypertension. This may be related to the lack of nocturnal decrease in sympathetic nervous activity.

Race and diurnal blood pressure patterns. A review and meta-analysis

Investigators have reported variable findings regarding the role of race in diurnal blood pressure patterns. We performed a review and meta-analysis of this literature to identify the overall effect of race on circadian blood pressure patterns. Eighteen studies involving 2852 participants were reviewed. Meta-analyses were conducted using effect sizes calculated from the data provided directly in the study reports. Separate meta-analyses were conducted on effect sizes for differences between blacks and whites in daytime and nighttime systolic and diastolic blood pressure and nocturnal dip in systolic and diastolic blood pressure. To evaluate discrepancies in findings from studies involving American versus non-American blacks, overall meta-analyses as well as within-subset meta-analyses of black/white differences were conducted for comparisons involving American and non-American blacks. Results of overall meta-analyses indicate that blacks experience higher levels of systolic and diastolic blood pressure, both at night and during the day. These differences were significantly greater at night than during the day (P<0.05). Results of within-subset analyses involving American blacks mirrored those for all black/white comparisons, except that the effect of race on nocturnal dip, ie, that American blacks experienced less of a dip in both systolic and diastolic blood pressure at night, was significant (P<0.05). In contrast, the effect of race on nocturnal dip was not significant for comparisons involving non-American blacks. These results suggest a consistent difference in the chronobiology of blood pressure, particularly in American blacks.