Nocturnal blood pressure fall on ambulatory monitoring in a large international database. The "Ad Hoc' Working Group

Lower ambulatory blood pressure in chronic fatigue syndrome

OBJECTIVE

To examine blood pressure circadian rhythm in subjects with chronic fatigue syndrome (CFS) and appropriate normal and fatigued controls to correlate parameters of blood pressure regulation with perception of fatigue in an observational cohort study. The cause of CFS remains unknown and there are no effective treatments.

METHODS

To address whether inactivity was a confounder, we performed a 24-hour ambulatory blood pressure monitoring in the following three subject groups: 1) CFS patients (Fukuda Diagnostic criteria) (n = 38); 2) normal controls (n = 120); and 3) a fatigue comparison group (n = 47) with the autoimmune liver disease primary biliary cirrhosis (PBC). All patients completed a measure of fatigue severity (Fatigue Impact Scale). In view of the different demographics between the patient groups, patients were age- and sex-matched on a case-by-case basis to normal controls and blood pressure parameters were compared.

RESULTS

Compared with the control population, the CFS group had significantly lower systolic blood pressure (p < .0001) and mean arterial blood pressure (p = .0002) and exaggerated diurnal variation (p = .009). There was a significant inverse relationship between increasing fatigue and diurnal variation of blood pressure in both the CFS and PBC groups (p < .05).

CONCLUSION

Lower blood pressure and abnormal diurnal blood pressure regulation occur in patients with CFS. We would suggest the need for a randomized, placebo-controlled trial of agents to increase blood pressure such as midodrine in CFS patients with an autonomic phenotype.

Reappraisal of the diagnostic role of orthostatic hypotension in diabetes

OBJECTIVE

Given the controversial aspects of orthostatic hypotension (OH) testing in diabetes, we evaluated the diagnostic role for cardiac autonomic neuropathy (CAN) and for nondipping of OH, defined according to a fall in systolic blood pressure (BP) > or = 30 (30-OH) or > or = 20 mmHg (20-OH).

METHODS

164 diabetic patients underwent 24 hours BP monitoring, three heart rate cardiovascular tests, and OH test.

RESULTS

Compared to 30 mmHg, the 20 mmHg criterion increased the frequency of OH from 11 to 19.5%. Both 30-OH and 20-OH were associated with CAN (chi (2) = 30.5, P < 0.0001, and chi (2) = 45.1, P < 0.0001, respectively) and nondipping (chi (2) = 31.7, P < 0.0001, and chi (2) = 17.2, P = 0.0001, respectively). ROC curve for orthostatic systolic BP fall provided an AUC of 0.79 +/- 0.04 (95% CI 0.70-0.86) for diagnosing CAN and of 0.77 +/- 0.05 (95% CI 0.66-0.86) for diagnosing nondipping. Both 30-OH and 20-OH showed a low sensitivity and high specificity for CAN [sensitivity 31%, specificity 98%, Likelihood Ratio for a positive result (LR(+)) 17.1; and sensitivity 50%, specificity 95%, LR(+) 9.3, respectively], and for nondipping (sensitivity 40%, specificity 96%, LR(+) 8.9, and sensitivity 47%, specificity 87%, LR(+) 3.5, respectively), having 30-OH a higher LR(+) in both cases.

INTERPRETATION

OH had only moderate diagnostic accuracy, with high specificity and low sensitivity, for CAN, diagnosed on the basis of heart rate cardiovascular tests, and-as a novel finding-also for nondipping. A different definition of OH did not substantially affect its diagnostic characteristics, with just a slightly greater ability of the 30 mmHg criterion to estimate the probability of CAN and nondipping.

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.

Association between circadian rhythm of blood pressure and glucose tolerance status in normotensive, non-diabetic subjects

AIMS

To examine whether circadian rhythm of blood pressure (BP) is associated with glucose tolerance status in normotensive, non-diabetic subjects.

METHODS

A cross-sectional study recruited normotensive and non-diabetic subjects, aged 35-79 years. A 75 g oral glucose tolerance test (OGTT) and 24-h ambulatory blood pressure monitoring (24-h ABPM) were performed.

RESULTS

Among 31 impaired glucose tolerance (IGT) and 36 normal glucose tolerance (NGT) study subjects, the mean (+/-S.D.) diurnal-nocturnal differences of average systolic BP (SBP) were 7.1+/-6.9 and 9.9+/-6.2 mmHg, respectively (p=0.086). In a linear mixed-effects regression model, however, taking each measurement of BP as the outcome, nighttime reduction of SBP in the IGT group was 7.19 mmHg, which was significantly smaller compared to a reduction of 9.80 mmHg in the NGT group (p-value for IGT: nighttime interaction=0.0014). The prevalence of non-dipping BP pattern was 77.4% in the IGT group which was significantly higher than 52.8% of the NGT group (p=0.036). Logistic regression revealed a significant effect of IGT for predicting non-dipping pattern with an adjusted odds ratio of 3.71 (95% CI: 1.09, 12.66, p=0.029).

CONCLUSIONS

Among normotensive, non-diabetic subjects, the decreased nocturnal BP reduction was associated with impaired glucose tolerance status.

Nocturnal blood pressure dipping in the hypertension of autonomic failure

Blood pressure (BP) normally decreases during the night. Absence of this phenomenon (nondipping) is associated with increased cardiovascular risk. Altered autonomic and endocrine circadian rhythms are suspected to play a role. Patients with peripheral autonomic failure offer a unique opportunity to study this phenomenon, because approximately 50% develop supine hypertension despite very low autonomic function. The purpose of this study was to define the prevalence of dipping in these patients and to determine whether dipping is associated with less severe autonomic impairment or exaggerated nocturnal sodium excretion. We collected BP and urine from 8:00 pm to 8:00 am in 41 peripheral autonomic failure patients with supine hypertension. Dipping (systolic BP fall >or=10% during 12 am to 6 am from baseline [8 pm to 10 pm]) occurred in 34% of patients, with an average decrease of -44+/-4 mm Hg at 4 am. Systolic BP, averaged from 12 am to 6 am, decreased to normotensive levels in 50% (n=7) of dippers and 15% (n=7) of nondippers. There were no significant differences in the severity of autonomic failure, nocturnal diuresis, or natriuresis (0.18+/-0.01 in dippers versus 0.18+/-0.01 mEq/mg of creatinine in nondippers; P=0.522) between groups. At 8:00 am, orthostatic hypotension was similar between groups (-84/-35+/-9/4 mm Hg in dippers versus -93/-39+/-6/3 mm Hg in nondippers; P=0.356 for systolic BP). In conclusion, dipping was observed in one third of patients with peripheral autonomic failure, so that a significant percentage of patients would not require treatment for supine hypertension. Dipping was not associated with increased nocturnal urinary sodium or volume excretion or less severe autonomic failure. Thus, mechanisms independent of autonomic pathways contribute to BP dipping in these patients.

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.

Different classifications of nocturnal blood pressure dipping affect the prevalence of dippers and nondippers and the relation with target-organ damage

OBJECTIVE

We assessed how different definitions of the awake and asleep periods and use of various blood pressure (BP) indices affect the extent of the nocturnal BP dip, the prevalence of dippers and nondippers, their respective reproducibilities and the relation of nondipping with target-organ damage.

METHODS

We performed 24-h ambulatory BP monitoring twice and determined the left ventricular mass index and urinary albumin excretion as indices of target-organ damage in 150 hypertensive patients (off-medication). Awake and asleep periods were assessed using fixed and diary time methods, covering all readings available (wide) or excluding morning and evening transition hours (narrow). Nondipping (BP dip < 10%) was established for systolic BP and diastolic BP, their combinations (and/or), and mean arterial pressure.

RESULTS

The different awake-asleep definitions caused significant variation in both the extent of the BP dip and the number of dippers and nondippers in comparison with the wide diary definition (i.e. use of actual awake and sleep periods). The prevalences of dippers and nondippers also varied significantly with the BP index. Reproducibility analyses of the BP dip and the dipping status yielded repeatability coefficients (expressed as percentages of nearly maximal variation) between 42.39 and 48.71%, and kappa values between 0.323 and 0.459, respectively. Some classifications, but not all, discriminated significantly between consistent dippers and nondippers in terms of left ventricular mass index or urinary albumin excretion.

CONCLUSIONS

Use of different definitions of awake-asleep and BP indices affects significantly the classification of nocturnal BP dipping and its relation with hypertensive target-organ damage.

Circadian variability of blood pressure in obese children

BACKGROUND AND AIMS

The aim of the present study was to evaluate the circadian rhythm of blood pressure pattern in obese children, and to investigate if the lack of normal diurnal rhythm of blood pressure is associated with cardiovascular risk factors.

METHODS AND RESULTS

73 obese children (body weight [mean+/-SD]: 89.0+/-17.8 kg; age [mean+/-SD]: 14.2+/-2.3 years), 42 dippers and 31 non-dippers were investigated. Following ambulatory blood pressure monitoring (ABPM), physical fitness testing was performed on a treadmill. Physical working capacity at 130, -150, -170 beat/min (PWC-130, -150, -170), resting and peak oxygen consumption (VO(2)rest, VO(2)peak) were determined. Forty-two percent of obese children were non-dipper. PWC-130 (74.8+/-48.8 watts; 48.0+/-38.5 watts), PWC-150 (132.9+/-52.1 watts; 104.2+/-49.3 watts), PWC-170 (185.9+/-49.5 watts; 154.9+/-53.4 watts) and VO(2)rest, ([mean+/-SD]: 0.29+/-0.08 L/min; 0.26+/-0.07 L/min), and VO(2) peak (2.77+/-0.61 L/min; 2.44+/-0.62 L/min) were significantly lower in the non-dipper group, as compared to dippers (p<0.05). The prevalence of hypertension, on the basis of ABPM, was significantly higher in the non-dipper group (45.2% vs 83.9%, p<0.001). This is due to increased prevalence of masked hypertension in the non-dipper group (19.0% vs 32.3%, p<0.001).

CONCLUSION

The normal circadian variation of the blood pressure is frequently absent in obese children. Most of the non-dipper obese children are hypertensive, and their physical fitness is decreased.

Physiological sleep-dependent changes in arterial blood pressure: central autonomic commands and baroreflex control

Sleep is a heterogeneous behaviour. As a first approximation, it is subdivided objectively into two states: non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS). The mean value and variability of arterial blood pressure (ABP) decrease physiologically from wakefulness to NREMS. In REMS, there may be a further decrease or increase in mean ABP as well as phasic hypertensive events, which enhance the variability of ABP. The reduced mean ABP during NREMS results from a decrease in either heart rate or sympathetic vasoconstrictor tone. During REMS, sympathetic activity to the different cardiovascular effectors undergoes a substantial repatterning. Thus, the mean ABP in REMS reflects a balance between changes in cardiac output and constriction or dilatation of different vascular beds. In both sleep states, the phasic changes in ABP are driven by bursts of vasoconstriction, which may be accompanied by surges of heart rate. The available evidence supports the hypothesis that the sleep-dependent changes in ABP, either tonic or phasic, result from the integration between cardiovascular reflexes and central autonomic commands that are specific to each sleep state.

Association of ambulatory arterial stiffness index and brachial pulse pressure is restricted to dippers

BACKGROUND

The ambulatory arterial stiffness index (AASI) is a new index that reflects the dynamic relation between diastolic and systolic blood pressure through the circadian blood pressure rhythm. It was the aim of this study to investigate the association between AASI, dipping status and pulse pressure as a classical indicator of arterial stiffness in normotensive and hypertensive subjects.

METHODS

One hundred and twelve individuals were evaluated for a kidney donation to a relative at the University Hospital Essen, Germany. In this context routine 24-h ambulatory blood pressure measurements were performed. A nocturnal reduction in diastolic blood pressure of >10% was defined as 'dipping'. We determined the diurnal and nocturnal blood pressure and brachial pulse pressure values and computed AASI for each participant.

RESULTS

AASI was a strong predictor for diastolic and systolic nocturnal blood pressure fall (r = -0.55 and -0.48, respectively; P < 0.001). Additionally, AASI predicted the status of 'dipping/nondipping'. 'Dippers' showed significantly lower AASI than 'nondippers' in both normotensive and hypertensive subjects. Dippers, but not nondippers, demonstrated an association between AASI and brachial pulse pressure.

DISCUSSION

AASI is strongly correlated with nocturnal blood pressure fall and is increased in nondipping independent of blood pressure. The role of AASI as a potential marker for arterial stiffness depends, in this study, on the characterization of the dipping status.

Nocturnal blood pressure fall and metabolic syndrome score in hypertensive patients

BACKGROUND

Data relating dipping status to metabolic syndrome (MS) scores are not available. The purpose of this study is to investigate any possible association of different dipping patterns to MS scores in untreated patients with essential hypertension.

METHODS

The study included 6256 consecutive, treatment-naive patients with essential hypertension who attended our outpatient clinics. All underwent repeated office blood pressure measurements, 24-h ambulatory blood pressure monitoring, and full clinical and laboratory evaluation. The diagnosis of MS was made according to the Adult Treatment Panel III criteria and patients were classified into five groups: group I (hypertension), group II (hypertension+any one component), group III (hypertension+any two components), group IV (hypertension+any three components), and group V (all five components). Dipping pattern was defined as 'dippers' with nocturnal systolic blood pressure (NSBP) falling >or=10 but <20%, 'nondippers' with NSBP falling >or=0% but <10%, 'extreme dippers' with NSBP falling >or=20%, and 'reverse dippers' with NSBP increasing.

RESULTS

Hypertensive patients with MS (n=2573) had higher clinical and ambulatory blood pressure values (P<0.001), whereas the dominant dipping pattern in the non-MS group was nondippers (47.6%), and in the MS group, extreme dippers (37.8%). Furthermore, a considerable decrease in the prevalence of dippers was noticed with the increasing number of MS components (21.1 vs. 19.2 vs. 14.5 vs. 8.4 vs. 7.2%, P<0.001). In contrast, a significant rise in the prevalence of reverse dippers was observed with the increasing number of MS components (7.4 vs. 10.1 vs. 14.9 vs. 20.4 vs. 31.2%, P<0.001).

CONCLUSIONS

It seems that hypertensive patients have an increased prevalence of abnormal dipping patterns as the number of MS components rises.

Ambulatory blood pressure and increased left ventricular mass in children at risk for hypertension

OBJECTIVE

To relate ambulatory blood pressure (ABP) to cardiac target organ measurement in children at risk for primary hypertension (HTN).

STUDY DESIGN

Left ventricular mass index (LVMI) and ABP were measured concomitantly in children (6 to 18 years) at risk for hypertension using a cross-sectional study design.

RESULTS

LVMI showed a significant positive correlation with 24-hour systolic blood pressure (SBP) load, SBP index (SBPI), and standard deviation score (SDS). When subjects were stratified by LVMI percentile, there were significant differences in SBP load, 24-hour SBPI, and 24-hour SSDS. The odds ratio (OR) of having elevated LVMI increased by 54% for each incremental increase of SDS in 24-hour SSDS after controlling for race and BMI (OR = 1.54, unit = 1 SDS, CI = 1.1, 2.15, P = .011) and increased by 88% for each increase of 0.1 in BPI (OR = 1.88, CI = 1.03, 3.45, P = .04). Subjects with stage 3 HTN had significantly greater mean LVMI compared with normal subjects (P = .002 by ANOVA; LMVI, 31.6 +/- 7.9 versus 39.5 +/- 10.4).

CONCLUSIONS

As systolic ABP variables increase, there is greater likelihood for increased LVMI. Staging based on ABPM allows assessment of cardiovascular risk in children with primary hypertension.

Predictors of mortality in patients with type 2 diabetes with or without diabetic nephropathy: a follow-up study

OBJECTIVE

To evaluate the prognostic significance of cardiovascular risk factors including 24-h ambulatory blood pressure level and rhythm for all-cause mortality in type 2 diabetic patients.

METHODS

In a prospective observational study, 104 patients with type 2 diabetes were followed: 51 patients with diabetic nephropathy and 53 patients with persistent normoalbuminuria. At baseline, 24-h ambulatory blood pressure, left ventricular hypertrophy, glomerular filtration rate and cardiac autonomic neuropathy were measured. Blood samples were taken and patients answered a World Health Organization questionnaire. Dipping was calculated as the average nocturnal reduction in systolic and diastolic blood pressure.

RESULTS

Mean follow-up was 9.2 years (range 0.5-12.9). During follow-up, 54 of 104 patients died. Sixteen patients (15%) had higher blood pressure at night than during the day (reversed pattern); 14 of these patients died (88%), compared to 40 of 88 patients (45%) with reduced dipping or normal dipping; log rank P = 0.001. In a Cox regression analysis, predictors of all-cause mortality were: age, male sex, presence of left ventricular hypertrophy, glycated haemoglobin A1c (HbA1c), daytime systolic blood pressure, cardiac autonomic neuropathy, glomerular filtration rate and dipping (1% increase; hazard ratio 0.97, 95% confidence interval 0.94-0.998, P = 0.033).

CONCLUSION

Type 2 diabetes patients with non-dipping of night blood pressure were at higher risk of death as compared to dippers, independent of known cardiovascular risk factors. Since non-dipping has a high prevalence in patients with diabetic nephropathy, 24-h ambulatory blood pressure should be used to assess a full risk profile and blood pressure-lowering therapy in these patients.

Ambulatory blood pressure: associations with coronary heart disease in the aged Finnish population

BACKGROUND AND AIMS

Ambulatory blood pressure (ABP) has been shown to be a better predictor of cardiovascular events than clinical blood pressure (BP) in middle-aged and older populations. This study studied the association of various components of ABP (daytime, night-time, 24-hour ABP) in the presence of coronary heart disease (CHD) in an older Finnish population.

METHODS

This cross-sectional, observational, population-based study was carried out in The Lieto Health Centre, Finland, in 1998-99. The study population consisted of 502 subjects (237 men, 265 women) aged 64-87 years. ABP measurements for 24 hours, daytime (awake) and night-time (asleep), were made. Resting electrocardiograms (ECG) were recorded. A person was considered to have CHD if at least one of the following criteria was met: (I) history of coronary by-pass surgery or coronary angioplasty, (II) diagnosis of CHD in previous medical records, (III) ischemia-related changes on ECG.

RESULTS

CHD increased by 30% with a 10 mmHg increase in night-time systolic blood pressure (SBP) (OR 1.30, 95% Cl 1.15-1.47). When ambulatory 24-hour and daytime SBP values were each entered separately into the multivariate model, 24-hour SBP, but not daytime SBP, was associated with CHD.

CONCLUSIONS

The most important information gained from 24-h BP monitoring in subjects with CHD is night-time BP. Night-time BP may provide new information about the CHD risk which is not identified in common clinical diagnoses of hypertension. ABP measurements should be made to confirm sufficient control of night-time BP, especially SBP, in older people with CHD.

Prognostic accuracy of day versus night ambulatory blood pressure: a cohort study

BACKGROUND

Few studies have formally compared the predictive value of the blood pressure at night over and beyond the daytime value. We investigated the prognostic significance of the ambulatory blood pressure during night and day and of the night-to-day blood pressure ratio.

METHODS

We did 24-h blood pressure monitoring in 7458 people (mean age 56.8 years [SD 13.9]) enrolled in prospective population studies in Denmark, Belgium, Japan, Sweden, Uruguay, and China. We calculated multivariate-adjusted hazard ratios for daytime and night-time blood pressure and the systolic night-to-day ratio, while adjusting for cohort and cardiovascular risk factors.

FINDINGS

Median follow-up was 9.6 years (5th to 95th percentile 2.5-13.7). Adjusted for daytime blood pressure, night-time blood pressure predicted total (n=983; p<0.0001), cardiovascular (n=387; p<0.01), and non-cardiovascular (n=560; p<0.001) mortality. Conversely, adjusted for night-time blood pressure, daytime blood pressure predicted only non-cardiovascular mortality (p<0.05), with lower blood pressure levels being associated with increased risk. Both daytime and night-time blood pressure consistently predicted all cardiovascular events (n=943; p<0.05) and stroke (n=420; p<0.01). Adjusted for night-time blood pressure, daytime blood pressure lost prognostic significance only for cardiac events (n=525; p> or =0.07). Adjusted for the 24-h blood pressure, night-to-day ratio predicted mortality, but not fatal combined with non-fatal events. Antihypertensive drug treatment removed the significant association between cardiovascular events and the daytime blood pressure. Participants with systolic night-to-day ratio value of 1 or more were older, at higher risk of death, and died at an older age than those whose night-to-day ratio was normal (> or =0.80 to <0.90).

INTERPRETATION

In contrast to commonly held views, daytime blood pressure adjusted for night-time blood pressure predicts fatal combined with non-fatal cardiovascular events, except in treated patients, in whom antihypertensive drugs might reduce blood pressure during the day, but not at night. The increased mortality in patients with higher night-time than daytime blood pressure probably indicates reverse causality. Our findings support recording the ambulatory blood pressure during the whole day.

The International Database of Ambulatory Blood Pressure in relation to Cardiovascular Outcome (IDACO): protocol and research perspectives

OBJECTIVES

The International Database on Ambulatory Blood Pressure Monitoring (1993-1994) lacked a prospective dimension. We are constructing a new resource of longitudinal population studies to investigate with great precision to what extent the ambulatory blood pressure improves risk stratification.

METHODS

The acronym IDACO refers to the new International Database of Ambulatory blood pressure in relation to Cardiovascular Outcome. Eligible studies are population based, have fatal as well as nonfatal outcomes available for analysis, comply with ethical standards, and have been previously published in peer-reviewed journals. In a meta-analysis based on individual patient data, composite and cause-specific cardiovascular events will be related to various indexes derived by ambulatory blood pressure monitoring. The analyses will be stratified by cohort and adjusted for the conventional blood pressure and other cardiovascular risk factors.

RESULTS

To date, the international database includes 7609 patients from four cohorts recruited in Copenhagen, Denmark (n=2311), Noorderkempen, Belgium (n=2542), Ohasama, Japan (n=1535), and Uppsala, Sweden (n=1221). In these four cohorts, during a total of 69,295 person-years of follow-up (median 9.3 years), 1026 patients died and 929 participants experienced a fatal or nonfatal cardiovascular event. Follow-up in five other eligible cohorts, involving a total of 4027 participants, is still in progress. We expect that this follow-up will be completed by the end of 2007.

CONCLUSION

The international database of ambulatory blood pressure in relation to cardiovascular outcome will provide a shared resource to investigate risk stratification by ambulatory blood pressure monitoring to an extent not possible in any earlier individual study.

Sympathoadrenergic and metabolic factors are involved in ambulatory blood pressure rise in childhood obesity

We investigated in a young Italian obese population, the relationship between ambulatory BP (ABP) and several pathophysiological factors linking obesity to hypertension. A total of 89 obese children and adolescents underwent a 24-h ambulatory BP monitoring (ABPM) and an oral glucose tolerance test. The circulating levels of insulin, lipids, uric acid, C-reactive protein, interleukin-6, renin and aldosterone and the 24-h urinary levels of epinephrine, norepinephrine and albumin excretion rate were measured. Nine percent of subjects had daytime sustained hypertension (SH), 26% night-time hypertension and 11% a non-dipping pattern. SH subjects compared to those with sustained normotension (SN) were more obese (P<0.05), with a more frequent family history of hypertension (P<0.05), higher urinary catecholamine (P<0.05) and heart rate values (P<0.05) after adjustment for standard deviation score (SDS) of body mass index (BMI) and sex. Subjects with night-time hypertension compared to those with night-time normotension were more obese (P<0.0001), with a higher prevalence of impaired glucose tolerance (P<0.05) and metabolic syndrome (P<0.05) and higher 2-h glucose (P<0.05), uric acid (P<0.05) and triglycerides (P<0.05). In multivariate regression analysis, daytime systolic BP (SBP) remained independently correlated with urinary norepinephrine and SDS-BMI (P<0.05 for both), daytime diastolic BP (DBP) with waist circumference (P<0.05) and night-time SBP and DBP with SDS-BMI (P<0.01 for both). The risk of having systolic and diastolic hypertension increased with the increase in SDS-BMI and waist circumference, respectively. In conclusion, in our cohort of obese children and adolescents, daytime and night-time hypertension were associated with activation of the sympathoadrenal system and worst metabolic conditions, respectively.

Heritability of left ventricular mass in Japanese families living in Hawaii: the SAPPHIRe Study

OBJECTIVE

Established determinants of left ventricular (LV) mass explain only a modest fraction of its variability. Family studies to date suggest that a proportion of the unexplained variability can be accounted for by additive polygenic effects. An estimate of this proportion has not been reported previously in an East Asian population. The objective of this study was to estimate the heritability of LV mass in Japanese families living in Hawaii.

DESIGN AND METHODS

We analyzed data by components of variance in a sample of 169 hypertensive families (n = 476 subjects) and, separately, in a population-based sample of 256 families (n = 501 subjects) participating in the Honolulu Heart Program.

RESULTS

In multivariate models, established predictors of LV mass explained about half the total variance of LV mass. Using SOLAR, our estimates of the narrow sense heritability of LV mass ranged from 42.5% (SE 9.8, P < 0.0001) in our sample of hypertensive families to 60.6% (SE 11.7, P < 0.0001) in our population-based sample of families. Parametric bootstrap analyses confirmed that the inference for each sample was appropriate.

CONCLUSIONS

Assuming the absence of shared familial environmental effects, close to half of the unexplained variance of LV mass in Japanese subjects living in Hawaii is genetic in nature. This estimate was observed in two independent samples. Therefore, the pursuit of novel genetic determinants of LV mass through either whole genome or candidate gene association studies of this population may be worthwhile. Such studies are certainly feasible.

Systemic hypertension

Hypertension is a growing public health problem worldwide. Only 37% of American hypertensives currently have their blood pressures controlled. Hypertension is traditionally diagnosed in the medical office, but both home and ambulatory blood pressure monitoring can help. Lifestyle modifications are recommended for everyone who has higher than "normal" blood pressure (<120/80 mm Hg). Voluminous clinical trial data support beginning drug therapy with low-dose chlorthalidone, unless the patient has a specific indication for a different drug. Additional drugs (typically in the sequence, angiotensin converting-enzyme inhibitor or angiotensin receptor blocker, calcium antagonist, beta-blocker, alpha-blocker, aldosterone antagonist, direct vasodilator, and centrally acting alpha(2)-agonist) can be added to achieve the blood pressure goal (usually <140/90 mm Hg, but <130/80 mm Hg for diabetics and those with chronic kidney disease). Special circumstances exist for treatment of hypertension in pregnancy, in childhood, in the elderly, and in both extremes of blood pressure (pre-hypertension or hypertensive emergencies).

Circadian blood pressure variation: relationship between dipper status and measures of arterial stiffness

BACKGROUND

Compared with dippers, hypertensive individuals with a nondipping nocturnal blood pressure (BP) profile have more target organ damage and a worse cardiovascular prognosis, potentially mediated through arterial stiffness.

OBJECTIVE

To examine arterial stiffness and dipping in a population of 314 untreated hypertensive individuals, mean age 48 +/- 8 years, 55% men.

METHODS

Dipping was defined as a 10-20% fall in nocturnal BP; extreme dipping as greater than 20%, nondipping as less than 10%, and reverse-dipping as 0% at most fall in nocturnal BP. Aortic pulse wave velocity (PWV) (Complior) and augmentation index (Sphygmocor) were measured.

RESULTS

Groups did not differ by age, gender, 24-h or daytime mean BP, body mass index, smoking, cholesterol, glucose, renin or aldosterone. The relationship between PWV and dipper-status was J-shaped, with extreme-dippers and reverse-dippers having the highest PWV. Nondippers and reverse-dippers had significantly higher age and sex-adjusted PWV compared with dippers. Following multivariate adjustment for age, gender, mean arterial pressure, heart rate and smoking, reverse-dippers had significantly higher PWV than either dippers or nondippers (P = 0.005 and P = 0.006, respectively). Dipper status was not associated with augmentation index.

CONCLUSIONS

A reverse-dipper pattern, corresponding to the 95% percentile of the night: day BP ratio on ambulatory BP monitoring, identifies a population group with increased PWV. This difference could not be explained by the measured risk factors. Reverse-dippers had significantly less day: night variability in heart rate and wider pulse pressures at night than any of the other groups, suggesting altered sympathetic tone at night as a potential mechanism.

Ambulatory blood pressure monitoring in hypertensive patients with high cardiovascular risk: a cross-sectional analysis of a 20 000-patient database in Spain

OBJECTIVE

To evaluate ambulatory blood pressure monitoring (ABPM) parameters in a broad sample of high-risk hypertensive patients.

METHODS

The Spanish Society of Hypertension is developing a nationwide project in which more than 900 physicians send ABPM registries and corresponding clinical records to a central database via www.cardiorisc.com. Between June 2004 and July 2005 a 20 000-patient database was obtained; 17 219 were valid for analysis.

RESULTS

We identified 6534 patients with high cardiovascular risk according to the 2003 European Society of Hypertension/European Society of Cardiology guidelines stratification score. Office blood pressure (BP) was 158.8/89.9 mmHg and 24-h BP was 135.8/77.0 mmHg. Patients with grade 3 BP in the office showed ambulatory systolic BP values less than 160 mmHg in more than 80%. A non-dipping pattern was observed in 3836 cases (58.7%), whereas this abnormality was present in 47.9% of patients with low-to-moderate risk [odds ratio (OR) 1.54; 95% confidence interval (CI) 1.45-1.64]. The prevalence of non-dippers was higher as ambulatory BP increased ( approximately 70% when 24-h systolic BP > 155 mmHg) and was similar in both groups. At the lowest levels of BP (24-h systolic BP < 135 mmHg) a non-dipping pattern was more prevalent in high-risk cases (56.6 versus 45.7%; OR 1.51; 95% CI 1.40-1.64).

CONCLUSION

There was a remarkable discrepancy between office and ambulatory BP in high-risk hypertensive patients. The prevalence of a non-dipper BP pattern was almost 60%. In the lowest levels of ambulatory BP, high-risk patients showed a higher prevalence of non-dipping BP than lower-risk cases. These observations support the recommendation of a wider use of ABPM in high-risk hypertensive patients.

Night-time blood pressure patterns and target organ damage: a review

BACKGROUND

Individuals who do not have a 10% to 20% reduction in blood pressure (BP) during the night are known as 'nondippers'. The cause of this nondipping phenomenon is not fully understood; however, there is a growing body of evidence linking a nondipping BP pattern with target organ damage.

OBJECTIVE

To review the literature and present an overview of the target organ damage found to be associated with a nondipping BP pattern.

METHODS

PubMed, CINAHL and Medscape searches of all available English language articles from 1986 to 2005 were performed. Search terms included 'BP nondipping', 'BP dipping' and 'target organ damage'.

RESULTS

There is evidence to suggest that individuals with hypertension who exhibit a nondipping BP profile are at higher risk of cardiac and extracardiac morbidity and mortality. In particular, nondippers with essential hypertension have been found to have more advanced left ventricular hypertrophy, left ventricular mass and left ventricular mass index, carotid artery wall thickness, carotid artery atherosclerotic plaques, silent cerebral infarct, stroke, cognitive impairment and microalbuminuria.

CONCLUSION

A better understanding of the importance of the circadian variations of BP may help to identify those at higher risk of cardiovascular morbidity and mortality, as well as lay the foundation for interventions to prevent/treat alterations in night-time BP patterns.

A review of telmisartan in the treatment of hypertension: blood pressure control in the early morning hours

Measurement of blood pressure in the clinic may provide a false impression of blood pressure control. Ambulatory blood pressure monitoring (ABPM) allows the automatic recording of the circadian variation in blood pressure and evaluation of the efficacy of antihypertensive medication throughout the dosing interval. Ambulatory blood pressure provides more effective prediction of cardiovascular risk; blood pressure control at the time of heightened risk in the early morning after waking and before taking the next dose of medication is becoming important in order to improve long-term prognosis. To achieve blood pressure control in the early morning, a long-acting antihypertensive agent is essential. Telmisartan, an angiotensin II receptor blocker, as well as having a terminal elimination half-life of 24 h, has a large volume of distribution due to its high lipophilicity. The efficacy of telmisartan 80 mg monotherapy has been demonstrated using ABPM, with superior reduction in mean values for the last 6 h of the dosing interval compared with ramipril 10 mg and valsartan 80 mg. In addition, telmisartan 80 mg provides superior blood pressure control after a missed dose compared with valsartan 160mg. When combined with hydrochlorothiazide (HCTZ) 12.5 mg, telmisartan 40mg and 80mg is more effective than losartan/HCTZ (50/12.5 mg) at the end of the dosing interval. Furthermore, greater reductions in last 6 h mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) are achieved with telmisartan/HCTZ (80/12.5 mg) than with valsartan/HCTZ (160/12.5 mg) in obese patients with type 2 diabetes and hypertension. Recent data from a large group of patients show that telmisartan 80 mg controls the early morning blood pressure surge more effectively than ramipril 5-10 mg and, thus, may have a greater beneficial effect on long-term cardiovascular risk. This supposition is being tested in the ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET) programme.

Usefulness of ambulatory blood pressure monitoring in predicting the presence of autonomic neuropathy in type I diabetic patients

This study investigated whether nondipping (defined as a day-night change in blood pressure (BP) <or=0%) could be assumed as a diagnostic index for autonomic neuropathy, and assessed its accuracy in discriminating between type I diabetic patients with and without autonomic neuropathy. In 87 type I diabetic patients with normal renal function (age 36+/-11, duration 17+/-9 years, serum creatinine 67.2+/-15.9 micromol/l), four cardiovascular tests and 24-h BP monitoring were performed, and the percentage day-night change (Delta) in systolic (SBP) and diastolic BP (DBP) was calculated. Sixteen patients had DeltaSBP and/or DeltaDBP <or=0%. In a multiple logistic regression with adjustment for sex, age, and body mass index, the odds ratio for having autonomic neuropathy was seven times higher in patients with DeltaSBP <or=0% as opposed to those without (odds ratio 6.97, CI 1.4-34.9, P=0.018). Using Receiver Operating Characteristic (ROC) analysis, DeltaBP showed an acceptable accuracy in discriminating between patients with and without autonomic neuropathy (area under the ROC curve 0.69+/-0.06 and 0.72+/-0.05 for DeltaSBP and DeltaDBP, respectively). Adequate cutoff values were 0% for DeltaSBP (sensitivity, 26%; specificity, 95%; positive predictive value, 87%) and 5% for DeltaDBP (sensitivity, 26%; specificity, 92%; positive predictive value, 81%). In type I diabetic patients with normal renal function, a value of DeltaSBP <or=0% identifies the presence of autonomic neuropathy with a very high chance. Nondipping at the cutoff proposed could be considered an adjunctive marker of autonomic neuropathy provided with a high specificity and low sensitivity.

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.

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.

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.

Blunted cardiovascular responses to daytime activities as related to reduced nocturnal blood pressure decline

BACKGROUND

Individuals showing less than a 10% decline in blood pressure at night ("nondippers") are known to be at increased risk for hypertension and other cardiovascular conditions.

PURPOSE

This research tested the assertion by Räikkönen et al. (1) that nondippers show blunted cardiovascular responses to activities during daytime hours.

METHODS

Ambulatory blood pressure and impedance monitoring was performed with 149 young adults in Singapore. At each daytime blood pressure reading, participants completed a computerized questionnaire indicating location, posture, physical activities, feelings, and social interactions.

RESULTS

Significant interactions between dipper status and feeling tired, location, posture, and physical activity provided qualified support for the blunting hypothesis. However, blunting of BP responses was not attributable to blunting of either cardiac output or total peripheral resistance responses.

CONCLUSION

Nondippers appear to show blunted daytime responses to certain types of daytime activities. However, these effects are limited and appear to be the result of different mechanisms than those responsible for reduced nighttime blood pressure decline.

A pilot study of continuous ambulatory monitoring of blood pressure in repeated preoperative autologous blood donation

BACKGROUND

The aim of this study was to investigate the occurrence of hypotension in the 24-hour period after preoperative autologous blood donation (PABD) in patients with and without hypertension.

STUDY DESIGN AND METHODS

In 20 patients, 24-hour ambulatory blood pressure monitoring (ABPM) was performed before PABD was started and on every donation day in two repeated phlebotomies.

RESULTS

Seven patients had no hypertension and 11 patients had hypertension. In 2 additional patients, hypertension was diagnosed during the study. Overall, the mean systolic BP (SBP) decreased from 131+/-15 mmHg before donation to 128+/-13 and 127+/-10 mmHg after Donations 1 and 2; the corresponding values for the diastolic BP (DBP) were 77+/-9, 75+/-9, and 73+/-7 mmHg, both without significant differences between the groups with and without hypertension. In single patients, substantial decreases of BP occurred, especially during the night. Two patients with and 2 without hypertension showed a nightly decrease in SBP and DBP of more than 10 percent (in 1 of these patients, more than 20%). Concerning diurnal BP variability, 1 patient with and 1 without hypertension, the latter showing a nightly decrease of SBP and DBP of more than 10 percent, also changed to the pattern of a nightly "extreme dipper" after PABD.

CONCLUSION

In 25 percent of the patients, changes of BP were observed during the 24-hour period after PABD, especially during the night, which are known to be associated with an increased risk of cerebral or myocardial ischemia. Whether those changes of BP lead to major morbidity or mortality requires further investigation.

Dynamics of the circadian blood pressure profiles after renal transplantation

BACKGROUND

Abnormalities of diurnal blood pressure (BP) rhythm ("nondipping") are well-described in dialysis patients, and have prognostic importance. It is controversial whether successful renal transplantation (RTx) improves diurnal BP rhythm. To date, no study has attempted to define and model the evolution of diurnal BP rhythm profiles from dialysis to engraftment, focusing on the immediate (4-6 weeks) and medium-term (>1 year) postengraftment periods.

METHODS

To test if kidney transplantation normalizes the BP profile, ambulatory blood pressure monitoring (ABPM) was performed in 20 living related transplants (age, 30.3+/-5.1 years; 11 males, on dialysis for 25.6 months) 1 month preRTx and repeated 1 month and >1 year (ABPM3) after successful RTx. Dipping was defined as a sleep-to-awake ratio>0.92 (for systolic BP) and >0.90 (for diastolic BP).

RESULTS

PreRTx only 15% patients were dippers. At 1 month postRTx (creatinine clearance, 65.8 ml/min), all patients were complete nondippers. However, after >1 year postRTx (creatinine clearance, 70.4 ml/min), 40% were now dippers. Most importantly, overall, 30% of the patients improved significantly their circadian rhythm (35.3% of the initial preRTx nondippers). Despite successful renal transplantation, 55% patients maintained unchanged their nondipping profile throughout all three ABPM recordings. The only determinants of "long-term" postRTx circadian rhythm are the contemporary level of the renal function and the baseline, dialysis dipping profile: SBP3 sleep-to-awake ratio is related with serum creatinine3 (r=0.58, P=0.001), creatinine clearance (r=-0.41, P=0.036) and SBP1 sleep-to-awake ratio (r=0.48, P=0.034); similarly DBP3 sleep-to-awake ratio is related with serum creatinine3 (r=0.63, P=0.001), creatinine clearance (r=-0.471, P=0.036) and SBP1 sleep-to-awake ratio (r=0.53, P=0.016). In all, 57% of the variance in dipping status can be attributed and explained by the contribution of renal function and initial circadian variability.

CONCLUSIONS

Half of the nondipper dialysis patients maintain a permanently abnormal circadian rhythm, despite successful RTx. In the short term, RTx is associated with a highly abnormal diurnal profile, exclusively related to ciclosporin dose and levels. However, in the longer term, renal transplantation leads to a significant improvement of the circadian blood pressure profile, influenced by the renal function level and by the pretransplantation dipping profile.

Prognostic value of 24-hour ambulatory blood pressure monitoring and of night/day ratio in nondiabetic, cardiovascular events-free hemodialysis patients

BACKGROUND

The use of 24-hour ambulatory blood pressure monitoring is increasing in end-stage renal disease (ESRD) patients but the prediction power for cardiovascular complications of time-averaged ambulatory blood pressure components has been little investigated in these patients.

METHODS

We analyzed the prognostic power of 24-hour ambulatory blood pressure monitoring for all-cause and cardiovascular mortality in 168 nondiabetic, events-free hemodialysis patients selected from a total dialysis population of about 450 patients.

RESULTS

During the follow-up period (38 +/- 22 months), 48 patients died, 29 of them of cardiovascular causes. On univariate Cox regression analyses, the night/day systolic ratio resulted to be the sole blood pressure indicator to be associated with all-cause and cardiovascular mortality while left ventricular hypertrophy (LVH) was a strong predictor of these outcomes. In multivariable Cox models not including LVH, the night/day systolic ratio maintained an independent prognostic value for incident outcomes. However, when both risk factors, LVH and night/day systolic ratio, were introduced into Cox models, LVH was no longer a significant predictor while the night/day systolic ratio became a predictor of marginal statistical significance.

CONCLUSION

The night/day ratio emerges as the sole ambulatory blood pressure monitoring-derived indicator providing significant prognostic information in patients with ESRD. However, this indicator as well as LVH loses substantial prediction power in statistical models including both risk factors. The results suggest that the night/day systolic ratio and LVH provide overlapping prognostic information, a phenomenon in keeping with the hypothesis that they represent a common pathway leading to adverse outcomes in ESRD.

Diurnal blood pressure pattern in patients with primary aldosteronism

BACKGROUND

The aim of the study was to evaluate diurnal blood pressure (BP) profiles in patients with primary aldosteronism and to compare them to those in subjects with essential hypertension. The effects of specific therapy on the circadian BP profiles have been studied.

MATERIALS AND METHODS

Sixty-four patients with primary aldosteronism were included in the study. Thirty of them revealed an aldosterone-producing adenoma (APA) and 34 had idiopathic hyperaldosteronism (IHA) due to bilateral adrenal hyperplasia.

RESULTS

We did not find any significant differences in ambulatory BP monitoring (ABPM) between patients with APA and IHA. However, the circadian BP variation in the patients with primary hyperaldosteronism due to APA was preserved, while the patients with IHA showed lower nocturnal decline in comparison with patients with essential hypertension. There was a significant decline in office and ambulatory BP levels after treatment in the patients with both APA and IHA. The awake-sleep BP difference in patients with APA remained unchanged after surgical treatment, while in patients with IHA the night-time systolic and diastolic BP decline was significantly higher after spironolactone treatment.

CONCLUSIONS

Primary hyperaldosteronism due to APA was associated with normal circadian BP variability and the surgical treatment led to highly significant decline in all BP parameters but had no influence on the extent of nocturnal BP variation. Spironolactone therapy restored normal nocturnal BP decline in patients with IHA. Reduction of night-time BP decline in patients with IHA is more likely to be related to the duration of the disease rather than to the aldosterone levels.

Effect of diet and exercise on pulse pressure and cardiac function in morbid obesity: analysis of 24-hour ambulatory blood pressure

Blood pressure is a major risk factor for cardiovascular events, although the role of pulse pressure, an independent predictor of arterial stiffness, has recently been emphasized. This study examines the baseline relationship between body mass index (BMI) and blood pressure indexes in 215 obese African Americans enrolled in a diet-exercise program. The subject population was 77% female, with a mean +/- SD age of 46.7+/-10.7 years and a mean BMI of 42.5+/-7.5 kg/m2. In addition, the authors prospectively examined the effect of weight loss on cardiovascular parameters in a subset of 25 participants. The results show a closer significant correlation between pulse pressure and BMI (b=1.97 kgm-1; p=0.001) than between systolic blood pressure and BMI (b=1.58 kgm-1; p=0.020). After 3 months of diet and exercise, average reductions were as follows: BMI, 4.2 kg/m2 (p<0.01); systolic blood pressure, 7.2 mm Hg (p<0.01); pulse pressure, 4.8 mm Hg (p<0.01); and cardiac output, 975 mL/min (p<0.01). Compliance index increased by 0.1 mL/mm Hg/m2 (p=0.03). The results highlight the potential value to cardiovascular health of a modest reduction in body weight in obese individuals.

Association of blunted nocturnal blood pressure dip with intracerebral hemorrhage

OBJECTIVES

Nondipping pattern of nocturnal blood pressure is associated with silent ischemic cerebrovascular lesions and lacunar infarctions. In this case-control study, we aimed to evaluate the association of diurnal blood pressure variation with the occurrence of intracerebral hemorrhage.

METHODS

Ambulatory blood pressure monitoring was performed at 21-28 days after ictus in 78 first-ever unselective consecutive patients with intracerebral hemorrhage and in 80 age-adjusted and sex-adjusted controls who were referred to the hypertension center of our institution. The degree of nocturnal blood pressure dip was calculated as [(mean daytime values-mean night-time values)/mean daytime values]x100. Nondippers were defined as patients who exhibited a <10% nocturnal dip in systolic blood pressure. Logistic regression models were constructed to assess the association of nondipping status with intracerebral hemorrhage after adjusting for potential confounders (cardiovascular risk factors, office and ambulatory blood pressure levels).

RESULTS

Prevalence of nondipping was significantly greater among cases than among controls (74.4% vs. 43.8%, P<0.001). Nondipping status was independently (P=0.033) associated with intracerebral hemorrhage (OR: 2.326, 95% CI: 1.068-5.050) in a multiple variable logistic regression model that adjusted for baseline characteristics, cardiovascular risk factors, office and ambulatory blood pressure variables. The magnitude of the nocturnal systolic blood pressure dipping was inversely related to the risk of intracerebral bleeding; the odds ratio for intracerebral hemorrhage associated with every 1% decrease in nocturnal systolic blood pressure dip was 1.143 (95% CI: 1.058-1.235, P=0.001).

CONCLUSIONS

Given the previous reports that nondipping contributes to the risk of cerebral infarction, our results indicate that blunted nocturnal blood pressure dip may be also associated with the occurrence of intracerebral hemorrhage.

Reduced nocturnal blood pressure dip and sustained nighttime hypertension are specific markers of secondary hypertension

OBJECTIVE

To investigate with the use of ambulatory blood pressure (BP) monitoring whether nocturnal BP dip and nighttime BP values are different in children with untreated primary and secondary hypertension.

STUDY DESIGN

Ambulatory BP monitoring studies from 145 children with untreated hypertension were retrospectively analyzed. Forty-five children had primary hypertension and 100 children had secondary hypertension.

RESULTS

Children with secondary hypertension had lower nocturnal BP dip for systolic and diastolic BP in comparison to children with primary hypertension (8% +/- 5% vs 14% +/- 4% for systolic and 14% +/- 7% vs 22% +/- 5% for diastolic BP, P < .0001 for both). Eleven percent of children with primary hypertension were classified as nondipper (BP dip <10%) for systolic BP and no child for diastolic BP; on the contrary, in children with secondary hypertension, 65% were nondippers for systolic and 21% for diastolic BP. Nocturnal systolic and diastolic BP loads were significantly greater in children with secondary hypertension than in those with primary hypertension.

CONCLUSIONS

Reduced nocturnal BP dip and sustained nighttime BP elevation are specific markers of secondary hypertension in children with untreated hypertension. Children with blunted nocturnal BP dip or sustained nighttime hypertension should be thoroughly investigated searching for the underlying cause of hypertension.

Ethnicity, sex, trait anger, and nocturnal blood pressure decline

This study examined the relationship of trait anger to nocturnal blood pressure decline among Singaporean young adults. One hundred forty-nine participants (51 Chinese, 51 Malays, 47 Indians, 49.7% men) participated in 24-h ambulatory monitoring for blood pressure and hemodynamic measures. Significant interactions were obtained between ethnicity and trait anger for systolic blood pressure and mean arterial pressure such that trait anger was significantly and negatively related to nocturnal blood pressure decline for Indians whereas this was not true for Chinese or Malays. Significant sex x trait anger interactions were obtained for systolic blood pressure, diastolic blood pressure, and mean arterial pressure in which trait anger was negatively related to blood pressure decline for men but not for women. Overall the results suggest that trait anger is a significant factor affecting nocturnal blood pressure decline particularly among Indians and men.

The relationship between 24-hour blood pressure readings, subcortical ischemic lesions and vascular dementia

BACKGROUND

Twenty-four-hour blood pressure (BP) readings have been found to correlate with hypertensive target organ damage. Lacunar infarcts (LI) and white matter lesions (WML) probably represent manifestations of cerebral hypertensive target organ damage. This study was conducted to better delineate the relationships between 24-hour BP measurements, LI/WML and small vessel disease cognitive impairment/vascular dementia (CI/VD).

METHODS

Two hundred patients with first-time symptomatic LI were examined with 24-hour BP monitoring. The degree of nocturnal BP dip, (daytime BP - nighttime BP)/daytime BP, was categorized into three groups: dippers (>0.1), nondippers (0-0.1) and reverse dippers (<0). WML were subdivided into periventricular hyperintensities (PVH) and subcortical hyperintensities.

RESULTS

The breakdown of patients was: 50% nondippers, 27.5% reverse dippers and 22.5% dippers. Forty-one patients (20.5%) were found to have CI and dementia. Male sex (OR 3.35; 95% CI 1.20-9.34), advanced PVH (OR 14.42; 95% CI 5.62-36.98) and absence of a dipping status (nondipper: OR 12.62; 95% CI 1.37-115.95; reverse dipper: OR 11.95; 95% CI 1.27-112.11) were independently associated with CIVD after multivariate analysis. High nighttime systolic BP (OR 3.93; 95% CI 1.38-11.17), high daytime (OR 2.06; 95% CI 1.03-4.04) and nighttime diastolic BP (OR 2.48; 95% CI 1.13-5.45) and absence of a dipping status (nondipper: OR 2.7; 95% CI 1.03-7.05; reverse dipper: OR 3.78; 95% CI 1.38-10.34) were significantly associated with PVH.

CONCLUSIONS

High prevalence of a nondipping status was found in the LI cohort. A nondipping status appears to be directly associated with CIVD independent of PVH. This study indicates the need for further studies to investigate whether or not controlling nighttime BP will help reduce the risk for CI/VD development.

The normal circadian pattern of blood pressure: implications for treatment

Blood pressure fluctuates over 24 h following a circadian rhythm that reaches a peak in the morning shortly after awakening. The onset of many acute cardiovascular and cerebrovascular events shows a synchronous cyclical pattern, with the highest incidence of morbidity and mortality in the early morning hours. Strong, although circumstantial, evidence suggests that the early morning surge in blood pressure may contribute to the onset of acute cardiovascular episodes. Sustained blood pressure control that blunts the early morning blood pressure surge may help to reduce the incidence of these events. Antihypertensive agents are needed that provide smooth and sustained blood pressure control for the full 24 h, including the risky early morning hours. The angiotensin II receptor blocker telmisartan given once daily, because of its long half-life and mechanism of action, is likely to confer benefit in terms of 24-h blood pressure control and may reduce cardiovascular risk at the time of greatest patient vulnerability.

Relation of nocturnal blood pressure dipping to cellular adhesion, inflammation and hemostasis

BACKGROUND

Subjects who fail to dip their nocturnal blood pressure (BP) are at substantially increased risk for cardiovascular diseases. The pathogenetic mechanisms of this relationship have not been elucidated. We investigated whether non-dipping would relate to procoagulant and proinflammatory activity.

DESIGN

Study participants were 76 unmedicated normotensive and hypertensive subjects (44 male, 32 female; 41 white, 35 black; mean age, 36 +/- 8 years) who underwent 24-h outpatient ambulatory BP monitoring. Based on whether their average nocturnal systolic BP relative to their average daytime systolic BP declined by less than 10%, 34 subjects were categorized as non-dippers. D-dimer, plasminogen activator inhibitor-1, von Willebrand factor, soluble intercellular adhesion molecule-1, and interleukin-6 were measured in plasma.

RESULTS

Multivariate analyses showed that D-dimer (median/interquartile range, 242/162-419 ng/ml versus 175/132-254 ng/ml; P=0.041), plasminogen activator inhibitor-1 (36/19-61 ng/ml versus 17/6-44 ng/ml; P=0.010), von Willebrand factor (122/91-179% versus 92/66-110%; P=0.001), and soluble intercellular adhesion molecule-1(227/187-291 ng/ml versus 206/185-247 ng/ml; P=0.044) were all higher in non-dippers than in dippers. Adjustment for gender, ethnicity, age, body mass index, smoking status, hypertension status, and social class revealed independent effects of non-dipping. Non-dippers continued to have higher D-dimer (P=0.030) and von Willebrand factor (P=0.034) than dippers. A similar trend not reaching statistical significance emerged for soluble intercellular adhesion molecule-1 (P=0.055). In contrast, dipping status had no effect on interleukin-6.

CONCLUSION

Nocturnal BP non-dipping is associated with elevated levels of molecules related to endothelial dysfunction and atherosclerosis. The finding provides one possible mechanism linking non-dipping with cardiovascular disease.

Circadian blood pressure profile in patients with Cushing's syndrome before and after treatment

The aim of the study was to evaluate the circadian blood pressure (BP) profiles in patients with two forms of Cushing's syndrome, and to compare them to those in patients with essential hypertension. The study included 100 patients with Cushing's syndrome (80 with pituitary adenomas and 20 with adrenal adenomas) and 40 with essential hypertension. Twenty-four-h ambulatory BP monitoring was performed before and after therapy. All 3 groups had similar office-, 24-h-, awake-, and sleep BP mean values. The awake-sleep differences between the patients with two forms of Cushing's syndrome were similar. The night-time BP decline in the patients with Cushing's disease, as well as in those with adrenal adenomas, was significantly lower than that in the patients with essential hypertension. In the patients with both forms of Cushing's syndrome, there was a highly significant decline in the office and ambulatory BP levels after the treatment, and the awake-sleep systolic BP difference became significantly higher. The night-time diastolic BP decline was significantly higher after treatment in patients with adrenal adenomas and not-significantly higher in patients with Cushing's disease. In the patients with Cushing's disease, the duration of hypertension was greater, and lower percentage of normalized BP after treatment was observed in comparison with the patients with adrenal adenomas. The significant negative correlation between duration of the disease and extent of the night-time BP decline suggests that the 'non-dipping' profile is related not only to hypercortisolism itself but also to the severity of hypertension and duration of the disease.

Linear dynamic features of ambulatory blood pressure in a population-based study

BACKGROUND

The objective of the present study was to characterize inter-individual variation in traits that measure linear dynamic features of ambulatory blood pressure (BP) measurements that may be used in future population studies to investigate the relationships between variation in genetic and environmental factors that influence BP regulation and risk of hypertension, and among hypertensives, provide new insights into variation in risk of target organ damage.

DESIGN

We obtained ambulatory BP measurements every 10 min over a 24-h period in 199 healthy non-Hispanic Whites (84 females, 115 males) from Rochester, Minnesota, USA.

METHODS

We then used the autocorrelation function (ACF) to measure linear dynamic features of the daytime and night-time observations in females and males separately. Re-sampling procedures were used to test whether these individuals had significant linear dependencies.

RESULTS

We found that systolic and diastolic ambulatory BP measurements in our sample have statistically significant linear dependencies and that the ACFs are approximately normally distributed among individuals. In addition, we found that the distributions of the ACF traits among individuals are not significantly correlated with the mean of the ambulatory BP measurements, are different in men and women, and are different during the daytime versus the night-time.

CONCLUSIONS

We conclude that ACF traits are different measures of BP than the mean that capture information about the biology of BP regulation reflected in the dynamics of a person's minute-to-minute and hour-to-hour BP phenotype. Studies of measures of linear dynamic features of BP are likely to offer new insights into the genetic and environmental factors that contribute to inter-individual variation in BP regulation and risk of future hypertension as well as new insights into the causes of variation in risk of target organ damage in individuals with established hypertension.