Ethnic differences in nocturnal blood pressure decline in treated hypertensives

Circadian disruptions and their role in the development of hypertension

Circadian fluctuations in physiological setpoints are determined by the suprachiasmatic nucleus (SCN) which exerts control over many target structures within and beyond the hypothalamus via projections. The SCN, or central pacemaker, orchestrates synchrony between the external environment and the internal circadian mechanism. The resulting cycles in hormone levels and autonomic nervous system (ANS) activity provide precise messages to specific organs, adjusting, for example, their sensitivity to approaching hormones or metabolites. The SCN responds to both photic (light) and non-photic input. Circadian patterns are found in both heart rate and blood pressure, which are linked to daily variations in activity and autonomic nervous system activity. Variations in blood pressure are of great interest as several cardiovascular diseases such as stroke, arrhythmias, and hypertension are linked to circadian rhythm dysregulation. The disruption of normal day-night cycles, such as in shift work, social jetlag, or eating outside of normal hours leads to desynchronization of the central and peripheral clocks. This desynchronization leads to disorganization of the cellular processes that are normally driven by the interactions of the SCN and photic input. Here, we review autonomic system function and dysfunction due to regulation and interaction between different cardiorespiratory brain centers and the SCN, as well as social, lifestyle, and external factors that may impact the circadian control of blood pressure.

While You Are Sleeping: Marital Ambivalence and Blunted Nocturnal Blood Pressure

Marital relationships offer health benefits, including a lower risk of cardiovascular disease (CVD). However, quality of the relationship matters; ambivalent behaviors may increase CVD risk by affecting blunted nocturnal blood pressure (BP) dipping. This study tracked daytime and nocturnal SBP and DBP in 180 normotensive individuals (90 couples; participant mean age 25.04; 91.58% white) over a 24 h period using ambulatory blood pressure monitors to explore the impact of martial quality. Results showed that perceptions of spousal ambivalence were associated with blunted nocturnal BP dipping. Perceptions of one's own behavior as ambivalent also showed blunted nocturnal dipping. When in an ambivalent relationship, a gender interaction was found such that women were most likely to have blunted SBP dipping, but men were more likely to have blunted nocturnal DBP dipping. Overall, this study found an association between ambivalence and BP dipping, thus uncovering one virtually unexplored pathway by which marital relationships may have adverse effects on health.

The Role of Race, Sex, and Age in Circadian Disruption and Metabolic Disorders

Circadian rhythms are 24-hour internal biological cycles that play an important role in metabolism, and their disruption has been implicated in the development of diseases such as diabetes mellitus type 2, obesity, coronary artery disease, hypertension, and metabolic syndrome. This phenomenon is illustrated by increased rates of risk factors for cardiovascular disease in night shift workers. Race, sex, and age are factors that play a role in circadian rhythms and metabolic disorders. The focus of this review article is to assess the link between circadian rhythm physiology and metabolic disorders from a race, sex, and age perspective. Black Americans were noted to have shorter free-running circadian periods, or tau, increased cortisol levels, and poorer sleep habits compared to white Americans, possibly contributing to increased rates of obesity, hypertension, and hyperlipidemia. Women were also noted to have shorter tau, increased levels of proinflammatory gut bacteria, and reduced sleep quality compared to men, possibly leading to higher rates of obesity, metabolic syndrome, hypertension (in postmenopausal women), and nonalcoholic fatty liver disease. Older people were noted to have decreased expression of anti-inflammatory clock genes compared to younger people, possibly leading to increased rates of obesity, diabetes, hyperlipidemia, and hypertension. Groups that are at a higher risk for metabolic disorders such as black Americans, women, and the elderly may have internal time keeping systems that place them at a higher risk for developing abnormal hormonal and/or inflammatory pathways.

Role of Blood Pressure Responses to Exercise and Vascular Insulin Sensitivity with Nocturnal Blood Pressure Dipping in Metabolic Syndrome

INTRODUCTION

Nocturnal systolic blood pressure (SBP) dipping is independently related to cardiovascular disease risk, but it is unclear if vascular insulin sensitivity associates with SBP dipping in patients with metabolic syndrome (MetS).

METHODS

Eighteen adults with MetS (ATP III criteria 3.3 ± 0.6; 53.2 ± 6.5 years; body mass index 35.8 ± 4.5 kg/m2) were categorized as "dippers" (≥10% change in SBP; n = 4 F/3 M) or "non-dippers" (<10%; n = 9 F/2 M). Twenty-four-hour ambulatory blood pressure was recorded to assess SBP dipping. A euglycemic-hyperinsulinemic clamp (40 mU/m2/min, 90 mg/dL) with ultrasound (flow mediated dilation) was performed to test vascular insulin sensitivity. A graded, incremental exercise test was conducted to estimate sympathetic activity. Heart rate (HR) recovery after exercise was then used to determine parasympathetic activity. Metabolic panels and body composition (DXA) were also tested.

RESULTS

Dippers had greater drops in SBP (16.63 ± 5.2 vs. 1.83 ± 5.6%, p < 0.01) and experienced an attenuated rise in both SBPslope (4.7 ± 2.3 vs. 7.2 ± 2.5 mm Hg/min, p = 0.05) and HRslope to the incremental exercise test compared to non-dippers (6.5 ± 0.9 vs. 8.2 ± 1.7 bpm/min, p = 0.03). SBP dipping correlated with higher insulin-stimulated flow-mediated dilation (r = 0.52, p = 0.03), although the relationship was no longer significant after covarying for HRslope (r = 0.42, p = 0.09).

CONCLUSION

Attenuated rises in blood pressure and HR to exercise appear to play a larger role than vascular insulin sensitivity in SBP dipping in adults with MetS.

Nocturnal Dipping and Left Ventricular Mass Index in the Chronic Kidney Disease in Children Cohort

BACKGROUND AND OBJECTIVES

The physiologic nocturnal BP decline is often blunted in patients with CKD; however, the consequences of BP nondipping in children are largely unknown. Our objective was to determine risk factors for nondipping and to investigate if nondipping is associated with higher left ventricular mass index in children with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a cross-sectional analysis of ambulatory BP monitoring and echocardiographic data in participants of the Chronic Kidney Disease in Children study. Multivariable linear and spline regression analyses were used to evaluate the relationship of risk factors with dipping and of dipping with left ventricular mass index.

RESULTS

Within 552 participants, mean age was 11 (±4) years, mean eGFR was 53 (±20) ml/min per 1.73 m2, and 41% were classified as nondippers. In participants with nonglomerular CKD, female sex and higher sodium intake were significantly associated with less systolic and diastolic dipping (P≤0.05). In those with glomerular CKD, Black race and greater proteinuria were significantly associated with less systolic and diastolic dipping (P≤0.05). Systolic dipping and diastolic dipping were not significantly associated with left ventricular mass index; however, in spline regression plots, diastolic dipping appeared to have a nonlinear relationship with left ventricular mass index. As compared with diastolic dipping of 20%-25%, dipping of <20% was associated with 1.41-g/m2.7-higher left ventricular mass index (95% confidence interval, -0.47 to 3.29), and dipping of >25% was associated with 1.98-g/m2.7-higher left ventricular mass index (95% confidence interval, -0.77 to 4.73), although these relationships did not achieve statistical significance.

CONCLUSIONS

Black race, female sex, and greater proteinuria and sodium intake were significantly associated with blunted dipping in children with CKD. We did not find a statistically significant association between dipping and left ventricular mass index.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2021_12_20_CJN09810721.mp3.

Nocturia as an Unrecognized Symptom of Uncontrolled Hypertension in Black Men Aged 35 to 49 Years

Background

Hypertension is assumed to be asymptomatic. Yet, clinically significant nocturia (≥2 nightly voids) constitutes a putative symptom of uncontrolled hypertension. Black men with hypertension may be prone to nocturia because of blunted nocturnal blood pressure (BP) dipping, diuretic drug use for hypertension, and comorbidity that predisposes to nocturia. Here, we test the hypothesis that nocturia is a common and potentially reversible symptom of uncontrolled hypertension in black men.

Methods and Results

We determined the strength of association between nocturia (≥2 nightly voids) and high BP (≥135/85 mm Hg) by conducting in‐person health interviews and measuring BP with an automated monitor in a large community‐based sample of black men in their barbershops. Because nocturia is prevalent and steeply age‐dependent after age 50 years, we studied men aged 35 to 49 years. Among 1673 black men (mean age, 43±4 years [SD]), those with hypertension were 56% more likely than men with normotension to have nocturia after adjustment for diabetes mellitus and sleep apnea (adjusted odds ratio, 1.56; 95% CI, 1.25–1.94 [P<0.0001]). Nocturia prevalence varied by hypertension status, ranging from 24% in men with normotension to 49% in men whose hypertension was medically treated but uncontrolled. Men with untreated hypertension were 39% more likely than men with normotension to report nocturia (P=0.02), whereas men whose hypertension was treated and controlled were no more likely than men with normotension to report nocturia (P=0.69).

Conclusions

Uncontrolled hypertension was an independent determinant of clinically important nocturia in a large cross‐sectional community‐based study of non‐Hispanic black men aged 35 to 49 years.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unqiue identifier: NCT 02321618.

Randomized Crossover Trial of the Impact of Morning or Evening Dosing of Antihypertensive Agents on 24-Hour Ambulatory Blood Pressure

Some data suggest that nocturnal dosing of antihypertensive agents may reduce cardiovascular outcomes more than daytime dosing. This trial was designed to evaluate whether ambulatory blood pressure monitoring levels differ by timing of drug dosing. Patients aged 18 to 80 years with reasonably controlled hypertension (≤150/≤90 mm Hg) on stable therapy of ≥1 antihypertensive agent were recruited from 2 centers in London and Thessaloniki. Patients were randomized to receive usual therapy either in the morning (6 am –11 am ) or evening (6 pm –11 pm ) for 12 weeks when participants crossed over to the alternative timing for a further 12 weeks. Clinic blood pressures and a 24-hour recording were taken at baseline, 12, and 24 weeks and routine blood tests were taken at baseline. The study had 80% power to detect 3 mm Hg difference in mean 24-hour systolic blood pressure (α=0.05) by time of dosing. A 2-level hierarchical regression model adjusted for center, period, and sequence was used. Of 103 recruited patients (mean age, 62; 44% female), 95 patients (92%) completed all three 24-hour recordings. Mean 24-hour systolic and diastolic blood pressures did not differ between daytime and evening dosing. Similarly, morning and evening dosing had no differential impact on mean daytime (7 am –10 pm ) and nighttime (10 pm –7 am ) blood pressure levels nor on clinic levels. Stratification by age (≤65/≥65 years) or sex did not affect results. In summary, among hypertensive patients with reasonably well-controlled blood pressure, the timing of antihypertensive drug administration (morning or evening) did not affect mean 24-hour or clinic blood pressure levels.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01669928.

Psychosocial Correlates of Nocturnal Blood Pressure Dipping in African Americans: The Jackson Heart Study

BACKGROUND

African Americans exhibit a lower degree of nocturnal blood pressure (BP) dipping compared with Whites, but the reasons for reduced BP dipping in this group are not fully understood. The aim of this study was to identify psychosocial factors associated with BP dipping in a population-based cohort of African Americans.

METHODS

This cross-sectional study included 668 Jackson Heart Study (JHS) participants with valid 24-hour ambulatory BP data and complete data on psychosocial factors of interest including stress, negative emotions, and psychosocial resources (e.g., perceived support). The association of each psychosocial factor with BP dipping percentage and nondipping status (defined as <10% BP dipping) was assessed using linear and Poisson regression models, respectively, with progressive adjustment for demographic, socioeconomic, biomedical, and behavioral factors.

RESULTS

The prevalence of nondipping was 64%. Higher depressive symptoms, higher hostility, and lower perceived social support were associated with a lower BP dipping percentage in unadjusted models and after adjustment for age, sex, body mass index, and mean 24-hour systolic BP (P < 0.05). Only perceived support was associated with BP dipping percentage in fully adjusted models. Also, after full multivariable adjustment, the prevalence ratio for nondipping BP associated with 1 SD (7.1 unit) increase in perceived support was 0.93 (95% CI: 0.88-0.99). No other psychosocial factors were associated with nondipping status.

CONCLUSIONS

Lower perceived support was associated with reduced BP dipping in this study. The role of social support as a potentially modifiable determinant of nocturnal BP dipping warrants further investigation.

Nocturnal Non-dipping Blood Pressure Profile in Black Normotensives Is Associated with Cardiac Target Organ Damage

PURPOSE

A non-dipping pattern of nocturnal blood pressure in hypertensive patients is an established predictor of cardiovascular risk, especially in Blacks. However, data on non-dipping normotensives and cardiovascular risk in this population is sparse. In this study, we aim to determine if a non-dipping profile in a cohort of Black normotensives is associated with cardiac target organ damage.

METHODS

We studied ambulatory blood pressure patterns in 43 normotensive Black patients of Caribbean origin and classified their profiles as dippers (DP) and non-dippers (NDP) based on their nocturnal blood pressure profiles. Cardiac target organ damage was estimated from 2-D echocardiogram.

RESULTS

The mean age of the cohort was 52 years. Both groups were similar with respect to baseline age, sex, weight, height, body mass index and daytime ambulatory BP. There was a statistically significant difference in nocturnal blood pressure between DP and NDP groups (112 ± 7/64 ± 2 mm Hg vs 117 ± 3/69 ± 2 mm Hg, P=.004). The NDP cohort showed evidence of cardiovascular target damage on echocardiography with a significantly increased relative wall thickness (.35 ± .07 cm vs .42 ± .05 cm, P=.001), left ventricular mass index (95 ± 14 vs 105 ± 14 g/m(2), P=.018) and left atrial volume index (26 ± 3.5 vs. 30 ± 3.4, P=.001). Left ventricular geometry in the non-dippers also showed increased concentric remodeling, concentric and eccentric hypertrophy.

CONCLUSIONS

Our study demonstrates that nocturnal non-dipping of blood pressure in normotensive Blacks of Caribbean origin may be associated with cardiovascular end organ damage thereby providing new surveillance and therapeutic targets.

The Association of Pediatric Obesity With Nocturnal Non-Dipping on 24-Hour Ambulatory Blood Pressure Monitoring

BACKGROUND

Obesity has been linked with abnormal nocturnal dipping of blood pressure (BP) in adults, which in turn is associated with poor cardiovascular outcomes. There are few data regarding abnormal dipping status in the obese pediatric population. The goal of this study was to further describe the relationship between obesity and non-dipping status on ambulatory blood pressure monitor (ABPM) in children.

METHODS

We conducted a cross-sectional study using a database of patients aged 5-21 years who had undergone 24-hour ABPM at Seattle Children's Hospital from January 2008 through May 2014. Subjects were grouped by body mass index (BMI) into lean (BMI 15th-85th percentile) and obese (BMI >95th percentile) groups.

RESULTS

Compared to lean subjects (n = 161), obese subjects (n = 247) had a prevalence ratio (PR) for non-dipping of 2.15, adjusted for race (95% confidence interval (CI) = 1.25-3.42). Increasing severity of obesity was not further associated with nocturnal non-dipping. Nocturnal non-dipping was not associated with left ventricular hypertrophy (PR = 1.01, 95% CI = 0.71-1.44).

CONCLUSIONS

These results suggest that in children, just as in adults, obesity is related to a relatively decreased dipping in nocturnal BP.

Determinants of day-night difference in blood pressure, a comparison with determinants of daytime and night-time blood pressure

Blunted day–night difference in blood pressure (BP) is an independent cardiovascular risk factor, although there is limited information on determinants of diurnal variation in BP. We investigated determinants of day–night difference in systolic (SBP) and diastolic (DBP) BP and how these compared with determinants of daytime and night-time SBP and DBP. We analysed the association of mean daytime, mean night-time and mean day–night difference (defined as (mean daytime−mean night-time)/mean daytime) in SBP and DBP with clinical, lifestyle and biochemical parameters from 1562 adult individuals (mean age 38.6) from 509 nuclear families recruited in the GRAPHIC Study. We estimated the heritability of the various BP phenotypes. In multivariate analysis, there were significant associations of age, sex, markers of adiposity (body mass index and waist–hip ratio), plasma lipids (total and low-density lipoprotein cholesterol and triglycerides), serum uric acid, alcohol intake and current smoking status on daytime or night-time SBP and/or DBP. Of these, only age (P=4.7 × 10⁻⁵), total cholesterol (P=0.002), plasma triglycerides (P=0.006) and current smoking (P=3.8 × 10⁻⁹) associated with day–night difference in SBP, and age (P=0.001), plasma triglyceride (P=2.2 × 10⁻⁵) and current smoking (3.8 × 10⁻⁴) associated with day–night difference in DBP. 24-h, daytime and night-time SBP and DBP showed substantial heritability (ranging from 18–43%). In contrast day–night difference in SBP showed a lower heritability (13%) while heritability of day–night difference in DBP was not significant. These data suggest that specific clinical, lifestyle and biochemical factors contribute to inter-individual variation in daytime, night-time and day–night differences in SBP and DBP. Variation in day–night differences in BP is largely non-genetic.

Night/day ratios of ambulatory blood pressure among healthy adolescents: roles of race, socioeconomic status, and psychosocial factors

BACKGROUND

Elevated nighttime blood pressure (BP) predicts hypertension and its complications in adulthood.

PURPOSE

This study aimed to assess the independent effects of race and family income on night/day BP among adolescents and to examine whether negative emotions, low positive resources, and unpleasant interactions during the day are also related.

METHODS

Healthy African American and Caucasian high school students (N = 239) wore an ambulatory BP monitor for 48 h, recorded quality of ongoing interpersonal interactions, and completed questionnaires.

RESULTS

African Americans and those with lower family income had higher night/day BP ratios. African Americans reporting greater negative emotions, lower positive resources, and more unpleasant interactions had higher night/day BP ratios.

CONCLUSIONS

Racial differences in night BP emerge by adolescence, independent of family income. African Americans, especially those high in negative emotions and low in positive resources, may be at higher relative risk for hypertension later in life in part due to elevated night BP.

Socioeconomic status, psychosocial factors, race and nocturnal blood pressure dipping in a Hispanic cohort

BACKGROUND

Little information is available about the relationship of socioeconomic status (SES) to blunted nocturnal ambulatory blood pressure (ABP) dipping among Hispanics and whether this relationship differs by race. We sought to characterize ABP nondipping and its determinants in a sample of Hispanics.

METHODS

We enrolled 180 Hispanic participants not on antihypertensive medications. SES was defined by years of educational attainment. All participants underwent 24-hour ABP monitoring. A decrease of <10% in the ratio between average awake and average asleep systolic BP was considered nondipping.

RESULTS

The mean age of the cohort was 67.1 ± 8.7, mean educational level was 9.4 ± 4.4 years, and 58.9% of the cohort was female. The cohort was comprised of 78.3% Caribbean Hispanics with the rest from Mexico and Central/South America; 41.4% self-identified as white Hispanic, 34.4% self-identified as black Hispanic, and 24.4% did not racially self- identify. The percentage of nondippers was 57.8%. Educational attainment (10.5 years vs. 8.6 years; P <0.01) was significantly higher among dippers than nondippers. In multivariable analyses, each 1-year increase in education was associated with a 9% reduction in the likelihood of being a nondipper (odds ratio [OR], 0.91; 95% confidence interval [CI], 0.84-0.98; P = 0.01). There were significantly greater odds of being a nondipper for black Hispanics than for white Hispanics (OR, 2.83, 95% CI, 1.29-6.23; P = 0.005). Higher SES was significantly protective of nondipping in white Hispanics but not black Hispanics.

CONCLUSIONS

These results document a substantial prevalence of nondipping in a cohort of predominantly normotensive Hispanics. Dipping status varied significantly by race. Lower SES is significantly associated with nondipping status, and race potentially impacts on this relation.

Salt sensitivity: a review with a focus on non-Hispanic blacks and Hispanics

The purpose of this review is to summarize the available information regarding salt sensitivity particularly as it relates to non-Hispanic blacks and Hispanics and to clarify possible etiologies, especially those that might shed light on potential treatment options. In non-Hispanic blacks, there is evidence that endothelial dysfunction, reduced potassium intake, decreased urinary kallikrein excretion, upregulation of sodium channel activity, dysfunction in atrial natriuretic peptide (ANP) production, and APOL1 gene nephropathy risk variants may cause or contribute to salt sensitivity. Supported treatment avenues include diets high in potassium and soybean protein, the components of which stimulate nitric oxide production. Racial heterogeneity complicates the study of salt sensitivity in Hispanic populations. Caribbean Hispanics, who have a higher proportion of African ancestry, may respond to commonly prescribed anti-hypertensive agents in a way that is characteristic of non-Hispanic black hypertensives. The low-renin hypertensive phenotype commonly seen in non-Hispanic blacks has been linked to salt sensitivity and may indicate an increased risk for salt sensitivity in a portion of the Hispanic population. In conclusion, increased morbidity and mortality associated with salt sensitivity mandates further studies evaluating the efficacy of tailored dietary and pharmacologic treatment in non-Hispanic blacks and determining the prevalence of low renin hypertension and salt sensitivity within the various subgroups of Hispanic Americans.

Social support and nocturnal blood pressure dipping: a systematic review

BACKGROUND

Attenuated nocturnal blood pressure (BP) dipping is a better predictor of cardiovascular disease (CVD) morbidity and mortality than resting BP measurements. Studies have reported associations between social support, variously defined, and BP dipping.

METHODS

A systematic review of the literature was conducted to investigate associations of functional and structural social support with nocturnal BP dipping assessed over a minimum of 24 hours.

RESULTS

A total of 297 articles were identified. Of these, 11 met criteria for inclusion; all studies were cross-sectional in design and included adult participants only (mean age = 19 to 72 years). Evidence was most consistent for an association between functional support and BP dipping, such that 5 of 7 studies reported statistically (or marginally) significant positive associations with BP dipping. Statistically significant functional support-BP dipping associations were moderate (standardized effect size (d) = 0.41) to large (d = 2.01) in magnitude. Studies examining structural support were fewer and relatively less consistent; however, preliminary evidence was observed for associations of marital status and social contact frequency with BP dipping. Statistically significant structural support findings were medium (d = 0.53) to large (d = 1.13) in magnitude.

CONCLUSIONS

Overall, findings suggest a link between higher levels of functional support and greater nocturnal BP dipping; preliminary evidence was also observed for the protective effects of marriage and social contact frequency. Nonetheless, the relatively small number of studies conducted to date and the heterogeneity of findings across meaningful subgroups suggest that additional research is needed to substantiate these conclusions.

Socioeconomic status, nocturnal blood pressure dipping, and psychosocial factors: a cross-sectional investigation in Mexican-American women

BACKGROUND

Despite established links between reduced nocturnal blood pressure (BP) dipping and cardiovascular disease, BP dipping research in Hispanics is limited.

PURPOSE

This study investigated socioeconomic status (SES) as a predictor of BP dipping and the contributions of psychosocial factors to this relationship. Analyses were conducted for the overall sample and separately for higher and lower acculturated women.

METHODS

Mexican-American women (N = 291; 40-65 years) reported demographics and completed psychosocial assessments and 36-h ambulatory BP monitoring.

RESULTS

Lower SES related to reduced BP dipping in the overall sample and in more US-acculturated women (r's = .17-.30, p's < .05), but not in less-acculturated women (r's = .07, p's > .10). An indirect effect model from SES to BP dipping via psychosocial resources/risk fits well across samples.

CONCLUSIONS

In Mexican-American women, the nature of SES gradients in BP dipping and the roles of psychosocial resources/risk differ by acculturation level.

Ethnic differences in the effects of the DASH diet on nocturnal blood pressure dipping in individuals with high blood pressure

BACKGROUND

Ethnic differences in nocturnal blood pressure (BP) dipping may contribute to the increased risk for adverse cardiovascular events noted in African Americans (AAs). The DASH (Dietary Approaches to Stop Hypertension) diet has been shown to be efficacious in lowering clinic and ambulatory BP; however, the effect of the DASH diet on BP dipping is unclear.

METHODS

One hundred and eighteen men and women with high clinic BP (systolic BP (SBP) 130-159; diastolic BP 85-99) and above ideal body weight were randomized to a DASH diet intervention or to a usual diet control (UC) condition. Measures of 24-h ambulatory BP were obtained at baseline and at the end of the 4-month intervention period.

RESULTS

At baseline, AAs (n = 43) displayed blunted nocturnal SBP dipping compared to Caucasians (CAs; n = 75) and were more likely to be categorized as nondippers (<10% nocturnal decline in SBP, AAs: 51% vs. CAs: 27%). AAs randomized to the DASH diet intervention showed a significant improvement in SBP dipping postintervention compared to AAs in the UC condition (P = 0.04), whereas there was no appreciable change in SBP dipping in CAs (P = 0.72). Following the intervention, ethnic differences in SBP dipping were no longer statistically significant (nondipper status: AAs: 44% vs. CAs: 32%; P = 0.19).

CONCLUSIONS

Our study provides preliminary evidence suggesting that in overweight men and women with high BP, AAs may be especially likely to benefit from augmented SBP dipping associated with consumption of the DASH diet.

Everyday discrimination and nocturnal blood pressure dipping in black and white americans

OBJECTIVE

To investigate whether an association exists between experiences of everyday discrimination and blood pressure (BP) dipping in a biracial sample of black and white adults. Attenuated nocturnal BP dipping is closely linked to cardiovascular morbidity and mortality. Self-reported experiences of everyday discrimination have also been associated with negative cardiovascular health outcomes.

METHODS

Seventy-eight hypertensive and normotensive women and men (n = 30 black and 48 white) reported on their experiences of everyday discrimination (Everyday Discrimination Scale) and underwent two separate 24-hour ambulatory BP monitoring (ABPM) sessions approximately 1 week apart.

RESULTS

Correlation analysis revealed that higher endorsement of everyday discrimination was significantly associated with less diastolic BP (DBP) and systolic BP (SBP) dipping (p < .05). Subsequent hierarchical regression analyses indicated that everyday discrimination explained 8% to 11% of the variance in SBP and DBP dipping above and beyond other demographic and life-style-related factors, including race, age, 24-hour BP, body mass index, and current socioeconomic status. The relationship between discrimination and dipping was significantly stronger on the second night of monitoring. Finally, analyses revealed that everyday discrimination mediated the relationship between race and BP dipping.

CONCLUSIONS

These findings suggest that experiences of everyday discrimination are associated with less nocturnal SBP and DBP dipping above and beyond the effect of known covariates. The use of multiple ABPM sessions may facilitate the detection of relationships between psychological variables and BP dipping.

Can nocturnal hypertension predict cardiovascular risk?

Nocturnal hypertension and non-dipping of blood pressure during sleep are distinct entities that often occur together and are regarded as important harbingers of poor cardiovascular prognosis. This review addresses several aspects related to these blood pressure abnormalities including definitions, diagnostic limitations, pathogenesis and associated patient profiles, prognostic significance, and therapeutic strategies. Taken together, persistent nocturnal hypertension and non-dipping blood pressure pattern, perhaps secondary to abnormal renal sodium handling and/or altered nocturnal sympathovagal balance, are strongly associated with deaths, cardiovascular events, and progressive loss of renal function, independent of daytime and 24-hour blood pressure. Several pharmacological and non-pharmacological approaches may restore nocturnal blood pressure and circadian blood pressure rhythm to normal; however, whether this translates to a clinically meaningful reduction in unfavorable cardiovascular and renal consequences remains to be seen.

Nocturnal non‐dipping pattern in untreated hypertensives at different cardiovascular risk according to the 2003 ESH/ESC guidelines

AIM

To evaluate in a large population of untreated, uncomplicated essential hypertensives the relationship between alterations in nocturnal blood pressure (BP) profile, i.e. non-dipping pattern, and total cardiovascular risk.

METHODS

A total of 580 consecutive patients with grade 1 or 2 hypertension, referred to our outpatient clinic, underwent the following procedures: (i) clinical and routine laboratory examinations; (ii) 24-h ambulatory BP monitoring; (iii) 24-h collection for microalbuminuria; (iv) echocardiography; and (v) carotid ultrasonography. Cardiovascular risk was assessed according to the stratification scheme suggested by the 2003 ESH/ESC guidelines.

RESULTS

According to this classification, 16.2% of the 580 patients were considered at low added risk, 42.4% at medium added risk and 41.4% at high added risk; 38.5% of the overall population was classified in the high-risk stratum because of at least one manifestation of target organ damage (TOD) and 6.3% for the presence of three or more risk factors. The prevalence rates of a non-dipping pattern (decrease in BP at night < or = 10% compared with the average daytime values) were 28.5% in low-risk, 32.6% in medium-risk and 42.2% in high-risk patients, respectively. CONCLUSIONS. Our findings show that the prevalence of a non-dipping profile is significantly greater in patients stratified at high compared with those at low and medium added risk.

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 importance of the clinical observer in the development of a white-coat effect in African-American patients with hypertension

INTRODUCTION

As the office-awake blood pressure (BP) difference (white-coat effect) in African-Americans has not been evaluated, we studied the ethnicity, professional status (nurse versus doctor) and sex of the observer on the white-coat effect in African-American patients with hypertension.

METHODS

Seated clinical BP measurements were obtained in random order by an African-American male research physician, a Caucasian male research physician, and a Caucasian female nurse who is of similar age and clinical experience. Within 1 week, ambulatory BP recordings were performed.

RESULTS

A total of 65 African-American patients [54+/-13 years, 55% women, body mass index (BMI) 31+/-6 kg/m, 62% on drug therapy, 28% current smokers] participated in the study. Twenty-two percent had a systolic white-coat effect >20 mmHg and 49% had a diastolic white-coat effect >10 mmHg (average of all observers). Although there were no differences in the magnitude of the white-coat effect among the three study observers, the primary physician's diastolic white-coat effect was significantly greater than that of the African-American physician (14+/-12 vs. 9+/-12, P=0.05), but not the systolic white-coat effect (16+/-16 vs. 10+/-16 mmHg, P=0.09). BMI positively correlated with the systolic and diastolic white-coat effect (r=0.30, P=0.02 and r=0.41, P=0.0001), but this correlation was true only for female patients in multiple regression analyses. BMI significantly predicted the systolic (P=0.043) and diastolic (P=0.004) white-coat effects.

CONCLUSION

A white-coat effect is relatively common in African-American patients with hypertension and is the largest when the observer is their usual doctor. The clinical observer's ethnicity or sex does not play an important role in generating a white-coat effect in African-American patients with hypertension.

Nighttime blood pressure and nocturnal dipping are associated with daytime urinary sodium excretion in African subjects

Blood pressure (BP) follows a circadian rhythm, with 10% to 15% lower values during nighttime than during daytime. The absence of a nocturnal BP decrease (dipping) is associated with target organ damage, but the determinants of dipping are poorly understood. We assessed whether the nighttime BP and the dipping are associated with the circadian pattern of sodium excretion. Ambulatory BP and daytime and nighttime urinary electrolyte excretion were measured simultaneously in 325 individuals of African descent from 73 families. When divided into sex-specific tertiles of day:night ratios of urinary sodium excretion rate, subjects in tertile 1 (with the lowest ratio) were 6.5 years older and had a 9.8-mm Hg higher nighttime systolic BP (SBP) and a 23% lower SBP dipping (expressed in percentage of day value) compared with subjects in tertile 3 (P for trend <0.01). After adjustment for age, the SBP difference across tertiles decreased to 5.4 mm Hg (P=0.002), and the SBP dipping difference decreased to 17% (P=0.05). A similar trend across tertiles was found with diastolic BP. In multivariate analyses, daytime urinary sodium and potassium concentrations were independently associated with nighttime SBP and SBP dipping (P<0.05 for each). These data, based on a large number of subjects, suggest that the capacity to excrete sodium during daytime is a significant determinant of nocturnal BP and dipping. This observation may help us to understand the pathophysiology and clinical consequences of nighttime BP and to develop therapeutic strategies to normalize the dipping profile in hypertensive patients.

Is Isolated Nocturnal Hypertension a Novel Clinical Entity?

We reported previously that normotensive Chinese had higher nighttime diastolic blood pressure compared with non-Chinese. We, therefore, studied the prevalence and characteristics of isolated nocturnal hypertension (HT) and its association with arterial stiffness, an intermediate sign of target organ damage. We recorded ambulatory blood pressure, the central and peripheral systolic augmentation indexes, the ambulatory arterial stiffness index, and brachial-ankle pulse wave velocity in 677 Chinese enrolled in the JingNing population study (53.6% women; mean age: 47.6 years). Prevalence was 10.9% for isolated nocturnal HT (≥120/70 mm Hg from 10:00 pm to 4:00 am ), 4.9% for isolated daytime HT (≥135/85 mm Hg from 8:00 am to 6:00 pm ), and 38.4% for day-night HT. Patients with isolated nocturnal HT, compared with subjects with ambulatory normotension (45.8%), were older (53.7 versus 40.7 years), more often reported alcohol intake (68.9% versus 51.0%), had faster nighttime pulse rate (62.8 versus 60.7 bpm), had higher serum cholesterol (5.12 versus 4.77 mmol/L), and had higher blood glucose (4.84 versus 4.38 mmol/L). Similar to patients with isolated daytime HT or day-night HT, patients with isolated nocturnal HT had higher indexes of arterial stiffness ( P <0.05) than subjects with ambulatory normotension (central augmentation index: 140% versus 134%; peripheral augmentation index: 82.6% versus 76.5%; ambulatory arterial stiffness index: 0.40 versus 0.35 U; brachial-ankle pulse wave velocity: 16.2 versus 14.7 m/s). Of 74 patients with isolated nocturnal HT, only 4 (5.4%) had hypertension on conventional office blood pressure measurement (≥140/90 mm Hg). In conclusion, isolated nocturnal HT can only be diagnosed by ambulatory blood pressure monitoring, is prevalent among Chinese, and is associated with increased arterial stiffness.

Ethnic Differences in Urine Concentration: Possible Relationship to Blood Pressure

The mechanisms that account for the susceptibility of black individuals to hypertension and their reduced ability to excrete sodium are poorly understood. Vasopressin administration has been shown in healthy humans to delay sodium excretion along with its antidiuretic action. Black individuals have been reported to have higher vasopressin levels than white individuals. Therefore, this study investigated retrospectively 24-h urine volume (V) and urine concentration index (urine-to-plasma ratio of creatinine concentration), as well as their possible relationships with BP, in a cohort of 141 healthy young black and white individuals (18 to 40 y). Black individuals were found to have a significantly lower V and higher urine concentration than white individuals, especially during daytime. In addition, they exhibited a blunted nocturnal fall in fluid and electrolyte excretion and a higher pulse pressure than white individuals. Higher urine concentration and lower V were associated significantly with higher PP (but not with systolic or diastolic BP) in men. These relations remained significant after adjustment for age, body mass index, and sodium and potassium excretion. These results suggest that an enhanced tendency to concentrate urine may delay the excretion of the daily ingested fluid and sodium and may increase pulse pressure in young normotensive individuals. The higher urine concentration that is observed in black individuals (which could represent an adaptation to better water conservation) may participate in their enhanced susceptibility to hypertension. If these results are confirmed in further studies, then vasopressin V2 receptor antagonists might offer a novel antihypertensive strategy, especially in the black population.

Non-dippers are associated with adverse cardiac remodeling and dysfunction (R1)

BACKGROUND

Non-dippers are known to carry a high risk of cardiovascular complications due to higher cumulative 24-h pressure load over time. In this study, we hypothesized that non-dippers would be associated with adverse cardiac remodeling and left ventricular (LV) dysfunction in treated hypertensive patients.

MATERIALS AND METHODS

A total of 150 outpatients treated with antihypertensive drugs for at least 1 year were enrolled. The patients were classified as non-dippers if their daytime ambulatory systolic and diastolic BP did not decrease by at least 10% during the night. LV diastolic function was assessed by measuring mitral inflow velocity (E), early diastolic mitral annulus tissue velocity (E') and LV systolic function was assessed by measuring systolic tissue velocity (S'), longitudinal systolic strain and strain rate.

RESULTS

The Cornell voltage product, LA volume index and LV mass index was significantly higher in non-dippers. Early diastolic mitral annulus tissue velocity (E') was lower and E/E' was higher in non-dippers suggestive of diastolic dysfunction. Systolic tissue velocity (S'), systolic strain and strain rate were significantly lower in non-dippers suggestive of systolic dysfunction. The non-dipper status, controlled for age, sex and LV mass index showed significant correlation with E' (beta=-0.203, P=0.002), E/E' (beta=0.354, P<0.001), S' (beta=-0.231, P=0.002), strain (beta=-0.162, P=0.040) and strain rate (beta=-0.186, P=0.015).

CONCLUSIONS

This study showed the non-dippers in treated hypertensive patients were associated with adverse cardiac remodeling and early LV dysfunction. Further studies to demonstrate the long term prognostic significance of this finding is warranted.

Nondipping blood pressure patterns among individuals with essential hypertension: a review of the literature

BACKGROUND

Researchers have discovered that blood pressure (BP) varies in a diurnal manner throughout a 24-hour period, being higher during the day and lower at night. Most people have a dipping BP pattern characterized by a nighttime BP that is 10-20% lower than their daytime BP. Individuals who experience a less than 10% reduction in nighttime BP are described as having a nondipping BP pattern. Although controversial, there is a growing body of evidence suggesting that a nondipping BP pattern is associated with a greater risk of target organ damage among individuals with essential hypertension.

AIM

To review the literature on the most common factors associated with nondipping BP patterns among individuals with essential hypertension.

METHODS

CINAHL (1982-March 2006), PubMed (1950-March 2006) and Cochrane Library (1966-March 2006) databases were searched using the keywords: dipper, dipping, nondipper, nondipping, ambulatory blood pressure monitoring, ABPM, hypertension, essential hypertension, high blood pressure, blood pressure, nocturnal blood pressure, nighttime blood pressure, diurnal blood pressure, and blood pressure patterns. Published studies, abstracts, dissertations as well as the reference lists of retrieved articles were reviewed. Studies were included if they involved subjects with only treated or untreated essential hypertension or those with samples of both nomotensive and treated or untreated essential hypertensive individuals. Additionally, studies needed to evaluate 24-hour, daytime and nighttime BP patterns.

RESULTS

There is some evidence to suggest advanced age, African-American ethnicity, female sex, postmenopausal status, sodium sensitivity, sleep apnea, sleep quality, anger, hostility, depression, stress, social support, and socioeconomic status have an association with nondipping BP patterns.

CONCLUSION

Knowledge of the potential factors associated with an altered nighttime BP pattern is of importance because it can help identify persons at risk for nondipping BP patterns and potential target organ damage. Furthermore, knowledge of these factors associated with a nondipping BP profile will lay the foundation for interventions to prevent/treat alterations in nighttime BP patterns.

Blood pressure control and cardiovascular outcomes in high-risk Hispanic patients--findings from the International Verapamil SR/Trandolapril Study (INVEST)

BACKGROUND

People of Hispanic origin are the fastest growing ethnic minority in the United States and often have hypertension and other comorbidities which increase the risk associated with coronary artery disease (CAD).

METHODS AND RESULTS

An analysis of the 8045 Hispanic patients enrolled in INVEST was conducted, and comparisons were made to the 14,531 non-Hispanic patients. INVEST was a prospective, randomized, open, blinded end point study in CAD patients with hypertension. After 61,835 patient-years of follow-up, treatment with either a verapamil sustained release (SR) or atenolol antihypertensive strategy resulted in greater blood pressure control in Hispanic patients, and Hispanic patients were at significantly lower risk of experiencing a nonfatal myocardial infarction, nonfatal stroke, or death (hazard ratio [HR] 0.87, 95% CI 0.78-0.97). Hispanic ethnicity was associated with an increase (HR 1.19, 95% CI 1.04-1.36), and randomization to the verapamil SR strategy was associated with a decrease (HR 0.85, 95% CI 0.76-0.95), in the risk of new-onset diabetes. Use of trandolapril in the verapamil SR strategy was associated with reduced risk of new-onset diabetes, whereas increasing doses of atenolol and hydrochlorothiazide in the atenolol strategy were associated with increased risk of new-onset diabetes.

CONCLUSIONS

The Hispanic cohort of INVEST had better blood pressure control and lower risk of adverse cardiovascular outcomes compared with the non-Hispanic cohort. A verapamil SR strategy is an alternative to an atenolol strategy for the treatment of Hispanic patients with hypertension and CAD and can reduce the risk of new-onset diabetes.

Awareness of hypertension and diabetes in the Hispanic community

Major barriers to awareness and control of hypertension and diabetes in Hispanic Americans include poor language comprehension, poor physician-patient communication, cultural differences, low educational level, and lack of health insurance. To better communicate the concerns about the risk factors for cardiovascular disease, physicians could use patient-education materials that include illustrations, familiarize themselves with their Hispanic patients and their preferences regarding communication (e.g., formality, close proximity, appropriately used touch), and advocate government action to make health insurance more affordable. An increase in Spanish-speaking physicians would help alleviate some of the confusion that Hispanic patients experience in their interactions with health care providers.

Sleep paralysis in African Americans with panic disorder

Studies have reported a wide range in lifetime prevalence of sleep paralysis (SP). This variation may stem from cultural factors, stressful life events and genetic differences in studied populations. We found that recurrent SP was more common among African-American participants, especially those with panic disorder. Recurrent SP was reported by 59% of African Americans with panic disorder, 7% of whites with panic disorder, 23% of African-American community volunteers and 6% of white community volunteers. Significantly more early life stressors were reported by African Americans than whites. Higher levels of psychosocial stressors, including poverty, racism and acculturation, may contribute to the higher rates of SP experienced by African Americans.

Disturbances in Renal Autoregulation and the Susceptibility to Hypertension-Induced Chronic Kidney Disease

The risk of developing chronic kidney disease in the setting of hypertension varies among patient populations. Black hypertensive patients have an increased risk of developing hypertension-induced chronic kidney disease even after taking into account socioeconomic factors. There is evidence to suggest that the kidney is intrinsically more susceptible to the damaging effects of hypertension in black patients. This susceptibility can be traced to disturbances in the way the kidney autoregulates. Impaired renal autoregulation may be the renal manifestation of a more widespread abnormality in endothelial function. Other conditions that can impair renal autoregulation and add to the risk of chronic kidney disease include low birth weight, obesity, insulin resistance, hyperuricemia, and hypercholesterolemia. To minimize the risk of chronic kidney disease in patients with impaired renal autoregulatory capability, strict blood pressure control is required. There is indirect evidence that blocking the renin-angiotensin system may improve renal autoregulation.

Relation between socioeconomic status, race-ethnicity, and left ventricular mass: the Northern Manhattan study

Increased left ventricular mass (LVM) and lower socioeconomic status (SES) are predictors of cardiovascular morbidity and mortality. Blacks and Hispanics are more likely to have higher LVM and lower SES. The relation between SES, race-ethnicity, and LVM has not been fully explored. Data were used from the NOMAS population-based sample of 1916 subjects living in Northern Manhattan. SES was characterized on the basis of educational attainment and divided into 4 categories. Echocardiography-defined LVM was indexed according to height at the allometric power of 2.7 and analyzed as a continuous variable. LVM varied by race in our cohort (blacks 48.9 g/m2.7, Hispanics 48.4 g/m2.7, whites 45.6 g/m2.7; P=0.004). Using ANCOVA, there was a significant inverse and graded association between mean LVM and SES for the total cohort. Mean LVM was 48.4 g/m2.7, 48.6 g/m2.7, 47.1 g/m2.7, and 45.3 g/m2.7 for the lowest to the highest educational level category (P trend=0.0004). This relationship remained among normotensives (P trend=0.0005) and was present for blacks (P trend=0.009), but not for whites (P trend=0.86) or Hispanics (P trend=0.47). The difference in mean LVM between the highest and lowest categories of education was 5.3 g/m2.7 for blacks, 0.0 g/m2.7 for whites, and 1.0 g/m2.7 for Hispanics. Lower SES is an independent predictor of increased LVM among hypertensive and normotensive blacks.