Blood pressure load--a better determinant of hypertension

Effect of Tai Chi vs Aerobic Exercise on Blood Pressure in Patients With Prehypertension: A Randomized Clinical Trial

Importance

Prehypertension increases the risk of developing hypertension and other cardiovascular diseases. Early and effective intervention for patients with prehypertension is highly important.

Objective

To assess the efficacy of Tai Chi vs aerobic exercise in patients with prehypertension.

Design, Setting, and Participants

This prospective, single-blinded randomized clinical trial was conducted between July 25, 2019, and January 24, 2022, at 2 tertiary public hospitals in China. Participants included 342 adults aged 18 to 65 years with prehypertension, defined as systolic blood pressure (SBP) of 120 to 139 mm Hg and/or diastolic BP (DBP) of 80 to 89 mm Hg.

Interventions

Participants were randomized in a 1:1 ratio to a Tai Chi group (n = 173) or an aerobic exercise group (n = 169). Both groups performed four 60-minute supervised sessions per week for 12 months.

Main Outcomes and Measures

The primary outcome was SBP at 12 months obtained in the office setting. Secondary outcomes included SBP at 6 months and DBP at 6 and 12 months obtained in the office setting and 24-hour ambulatory BP at 12 months.

Results

Of the 1189 patients screened, 342 (mean [SD] age, 49.3 [11.9] years; 166 men [48.5%] and 176 women [51.5%]) were randomized to 1 of 2 intervention groups: 173 to Tai Chi and 169 to aerobic exercise. At 12 months, the change in office SBP was significantly different between groups by -2.40 (95% CI, -4.39 to -0.41) mm Hg (P = .02), with a mean (SD) change of -7.01 (10.12) mm Hg in the Tai Chi group vs -4.61 (8.47) mm Hg in the aerobic exercise group. The analysis of office SBP at 6 months yielded similar results (-2.31 [95% CI, -3.94 to -0.67] mm Hg; P = .006). Additionally, 24-hour ambulatory SBP (-2.16 [95% CI, -3.84 to -0.47] mm Hg; P = .01) and nighttime ambulatory SBP (-4.08 [95% CI, -6.59 to -1.57] mm Hg; P = .002) were significantly reduced in the Tai Chi group compared with the aerobic exercise group.

Conclusions and Relevance

In this study including patients with prehypertension, a 12-month Tai Chi intervention was more effective than aerobic exercise in reducing SBP. These findings suggest that Tai Chi may help promote the prevention of cardiovascular disease in populations with prehypertension.

Trial Registration

Chinese Clinical Trial Registry Identifier: ChiCTR1900024368.

The Role of Blood Pressure Load in Ambulatory Blood Pressure Monitoring in Adults: A Literature Review of Current Evidence

BACKGROUND

The blood pressure load (BPL) is commonly defined as the percentage of readings in a 24-h ambulatory blood pressure monitoring (ABPM) study above a certain threshold, usually the upper normal limit. While it has been studied since the 1990s, the benefits of using this index have not been clearly demonstrated in adults. We present the first review on the associations of BPL with target organ damage (TOD) and clinical outcomes in adults, the major determinants for its role and utility in blood pressure measurement. We emphasize studies which evaluated whether BPL has added benefit to the average blood pressure indices on ABPM in predicting adverse outcomes.

METHODS

PubMed search for all English language papers mentioning ABPM and BPL.

RESULTS

While multiple studies assessed this question, the cumulative sample size is small. Whereas the associations of BPL with various TODs are evident, the available literature fails to demonstrate a clear and consistent added value for the BPL over the average blood pressure indices.

CONCLUSIONS

There is a need for prospective studies evaluating the role of BPL in blood pressure measurement. The current literature does not provide sound support for the use of BPL in clinical decisions.

Interpretation of Ambulatory Blood Pressure Monitoring for Risk Stratification in Hypertensive Patients: The 'Ambulatory Does Prediction Valid (ADPV)' Approach

Several outcome-based prospective investigations have provided solid data which support the prognostic value of 24 h ambulatory blood pressure over and beyond cardiovascular traditional risk factors. Average 24 h, daytime, and nighttime blood pressures are the principal components of the ambulatory blood pressure profile that have improved cardiovascular risk stratification beyond traditional risk factors. Furthermore, several additional ambulatory blood pressure measures have been investigated. The correct interpretation in clinical practice of ambulatory blood pressure monitoring needs a standardization of methods. Several algorithms for its clinical use have been proposed. Implementation of the results of ambulatory blood pressure monitoring in the management of individual subjects with the aim of improving risk stratification is challenging. We suggest that clinicians should focus attention on ambulatory blood pressure components which have been proven to act as the main independent predictors of outcome (average 24 h, daytime, and nighttime blood pressure, pulse pressure, dipping status, BP variability).

Cumulative Systolic Blood Pressure Load and Cardiovascular Risk in Patients With Diabetes

BACKGROUND

Standard measures of blood pressure (BP) do not account for both the magnitude and duration of exposure to elevated BP over time.

OBJECTIVES

The purpose of this study was to assess the association between cumulative systolic blood pressure (SBP) load and risk of cardiovascular events in patients with type 2 diabetes.

METHODS

A post hoc analysis of patients with type 2 diabetes followed by the ADVANCE-ON (Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation - Observational Study). Cumulative SBP load was defined as the area under curve for SBP values ≥130 mm Hg divided by the area under curve for all measured SBP values over a 24-month exposure period. HRs for the association between cumulative SBP load with major cardiovascular events and death were estimated using Cox models.

RESULTS

Over a median 7.6 years of follow-up, 1,469 major cardiovascular events, 1,615 deaths, and 660 cardiovascular deaths were observed in 9,338 participants. Each 1-SD increase in cumulative SBP load was associated with a 14% increase in major cardiovascular events (HR: 1.14; 95% CI: 1.09-1.20), 13% increase in all-cause mortality (HR: 1.13; 95% CI: 1.13-1.18), and 21% increase in cardiovascular death (HR: 1.21; 95% CI: 1.13-1.29). For the prediction of cardiovascular events and death, cumulative SBP load outperformed mean SBP, time-below-target SBP, and visit-to-visit SBP variability in terms of Akaike information criterion and net reclassification indexes.

CONCLUSIONS

Cumulative SBP load may provide better prediction of major cardiovascular events compared with traditional BP measures among patients with type 2 diabetes. These findings reinforce the importance of both the magnitude and duration of exposure to elevated SBP in assessing cardiovascular risk. (Action in Diabetes and Vascular Disease Preterax and Diamicron MR Controlled Evaluation Post Trial Observational Study [ADVANCE-ON]; NCT00949286).

Knowledge-driven feature engineering to detect multiple symptoms using ambulatory blood pressure monitoring data

BACKGROUND

Hypertension is a major health concern across the globe and needs to be properly diagnosed to so it can be treated and to mitigate for this critical health condition. In this context, ambulatory blood pressure monitoring is essential to provide for a proper diagnosis of hypertension, which may not be possible otherwise due to the white coat effect or masked hypertension. In this paper, the objective is to develop a model which incorporates expert's knowledge in the feature engineering process so as to accurately predict multiple medical conditions. As a case study, we have considered multiple symptoms related to hypertension and used an ambulatory blood pressure monitoring method to continuously acquire hypertension relevant data from a patient. The goal is to train a model with a minimum set of the most effective knowledge-driven features which are useful to detect multiple symptoms simultaneously using multi-class classification techniques.

METHOD

Artificial intelligence-based blood pressure monitoring techniques introduce a new dimension in the diagnosis of hypertension by enabling a continuous (24hours) analysis of systolic and diastolic blood pressure levels. In this work, we present a model that entails a knowledge-driven feature engineering method and implemented an ambulatory blood pressure monitoring system to diagnose multiple cardiac parameters and associated conditions simultaneously these include morning surge, circadian rhythm, and pulse pressure. The knowledge-driven features are extracted to improve the interpretability of the classification model and machine learning techniques (Random Forest, Naive Bayes, and KNN) were applied in a multi-label classification setup using RAkEL to classify multiple conditions simultaneously.

RESULTS

The results obtained (F 1 = 0.918) show that the Random forest technique has performed well for multilabel classification using knowledge-driven features. Our technique has also reduced the complexity of the model by reducing the number of features required to train a machine learning model.

CONCLUSION

Considering these results, we conclude that knowledge-driven feature engineering enhances the learning process by reducing the number of features given as input to the machine learning algorithm. The proposed feature engineering method considers expert's knowledge to develop better diagnosis models which are free from misleading data-driven noisy features in some situations. It is a white-box approach in which clinicians can under stand the importance of a feature while looking at its value.

Impact of the ambulatory blood pressure monitoring profile on cognitive and imaging findings of cerebral small-vessel disease in older adults with cognitive complaints

We investigated ambulatory blood pressure (BP) monitoring (ABPM) profiles and magnetic resonance imaging (MRI) findings of cerebral small-vessel disease (cSVD) in older adults with cognitive complaints who were grouped as follows: subjective cognitive decline, mild cognitive impairment, and dementia of Alzheimer's type. Group comparisons and correlation analyses among demographic characteristics, cognitive and MRI findings, and ABPM profiles were performed. Furthermore, multivariate logistic regression analyses for dependent variables of (1) dementia or not and (2) MRI criteria of subcortical vascular dementia (SVaD) or not were conducted with independent variables of dichotomized ABPM profiles. A total of 174 subjects (55 males and 119 females) were included: mean age 75.36 ± 7.13 years; Mini-Mental State Examination (MMSE) score 20.51 ± 6.23. No MRI and ABPM findings except medial temporal atrophy were different between three groups. Twenty-four-hour systolic BP (sBP) was correlated with MMSE score (r = -0.182; p = 0.022) and the severity of white matter hyperintensity (WMH) (r = 0.157; p = 0.048). A higher daytime sBP was associated with dementia (odds ratio (OR): 3.734; 95% confidence interval (CI): 1.041-13.390; p = 0.043) and MRI finding of SVaD (OR: 10.543; 95% CI: 1.161-95.740; p = 0.036). Although there were no differences in ABPM profiles between three groups, a higher BP-especially a higher sBP-correlated with cognitive dysfunction and severity of WMH in older adults. Only higher daytime sBP was an independent predictor for dementia and MRI findings of SVaD. Among various ABPM profiles in this study, a higher BP, especially a higher sBP, may be considered the most important for clinical and MRI findings of cSVD.

Increased ambulatory arterial stiffness index and blood pressure load in normotensive obese patients

OBJECTIVES

It has been shown that blood pressure (BP) values measured in obese subjects are higher than the individuals with normal weight, even in normotensive limits. However, data concerning the Ambulatory Arterial Stiffness Index (AASI) and blood pressure load in normotensive obese subjects is lacking. This study was aimed to compare the ambulatory arterial stiffness index and blood pressure load in normotensive obese and healthy controls.

METHODS

One hundred normotensive obese and one hundred normal weight subjects were included in this study. All subjects underwent 24-hour ambulatory blood pressure monitoring. Ambulatory arterial stiffness index was calculated from 24-hour ambulatory blood pressure monitoring records. Ambulatory arterial stiffness index was defined as one minus the regression slope of unedited 24-h diastolic on systolic blood pressures. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) load values were calculated from 24-hour ambulatory blood pressure monitoring analysis.

RESULTS

Ambulatory arterial stiffness index of the obese subjects was significantly higher than the healthy controls (0.48±0.2 vs. 0.33±0.11, p<0.001). 24-hours systolic blood pressure and diastolic blood pressure loads were significantly higher in obese subjects. Logistic regression analysis revealed that body mass index (BMI) was an independent predictor for an abnormal ambulatory arterial stiffness ındex (≥0.50) (OR: 1.137, 95% CI: 0.915-1.001, p=0.004).

CONCLUSION

Blood pressure load and ambulatory arterial stiffness index are increased in normotensive obese patients. Moreover, body mass index is an independent predictor for an abnormal ambulatory arterial stiffness index. Our results indicate that obese subjects are at higher risk for future cardiovascular events despite normal office BP levels.

Lower Blood Pressure Is Not Associated With Decreased Arterial Spin Labeling Estimates of Perfusion in Intracerebral Hemorrhage

Background

Subacute ischemic lesions in intracerebral hemorrhage (ICH) have been hypothesized to result from hypoperfusion. Although studies of cerebral blood flow (CBF) indicate modest hypoperfusion in ICH, these investigations have been limited to early time points. Arterial spin labeling (ASL), a magnetic resonance imaging technique, can be used to measure CBF without a contrast agent. We assessed CBF in patients with ICH using ASL and tested the hypothesis that CBF is related to systolic blood pressure (SBP).

Methods and Results

In this cross‐sectional study, patients with ICH were assessed with ASL at 48 hours, 7 days, and/or 30 days after onset. Relative CBF (rCBF; ratio of ipsilateral/contralateral perfusion) was measured in the perihematomal regions, hemispheres, border zones, and the perilesional area in patients with diffusion‐weighted imaging hyperintensities. Twenty‐patients (65% men; mean±SD age, 68.5±12.7 years) underwent imaging with ASL at 48 hours (N=12), day 7 (N=6), and day 30 (N=11). Median (interquartile range) hematoma volume was 13.1 (6.3–19.3) mL. Mean±SD baseline SBP was 185.4±25.5 mm Hg. Mean perihematomal rCBF was 0.9±0.2 at 48 hours at all time points. Baseline SBP and other SBP measurements were not associated with a decrease in rCBF in any of the regions of interest (P≥0.111). rCBF did not differ among time points in any of the regions of interest (P≥0.097). Mean perilesional rCBF was 1.04±0.65 and was unrelated to baseline SBP (P=0.105).

Conclusions

ASL can be used to measure rCBF in patients with acute and subacute ICH. Perihematomal CBF was not associated with SBP changes at any time point.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00963976.

An analysis of ambulatory blood pressure monitoring using multi-label classification

Ambulatory blood pressure monitoring (ABPM) involves measuring blood pressure by means of a tensiometer carried by the patient for a duration of 24 h, it currently occupies a central place in the diagnosis and follow-up of hypertensive patients, it provides crucial information which allows to make a specific diagnosis and adapt therapeutic attitude accordingly. The traditional analysis process suffers from different problems: it requires a lot of time and expertise, and several calculations should be performed manually by the expert, who is generally very busy. In this work, we attempt to improve the analysis of ABPM data using multi-label classification methods, where a record is associated with more than one label (class) at the same time. Seven algorithms are experimentally compared on a new multi-label ABPM-dataset. Experiments are conducted on 270 hypertensive patient records characterized by 40 attributes and associated with six labels. Results show that the multi-label modeling of ABPM data helps to investigate label dependencies and provide interesting insights, which can be integrated into the ABPM devices to dispense automatically detailed reports with possible future complications.

Renal artery stenosis and ambulatory blood pressure monitoring: A case report and review of the literature

Renal artery stenosis (RAS) is a prevalent cause of secondary hypertension. Elderly patients with atherosclerosis and young women with fibromuscular dysplasia (FMD) are particularly at risk. Blood pressure screening is often key to this diagnosis, although the reliability of clinical screening has been questioned, and ambulatory blood pressure monitoring (ABPM) likely offers superior ability to diagnose poorly controlled hypertension. In patients with RAS, medical management should be the primary means of therapy; however, in a select group of these patients, renal revascularization may be considered, and has been shown to reduce blood pressure and stabilize chronic kidney disease. In this report, we present a patient diagnosed with RAS due to FMD, found to have significant hypertension via ABPM, and treated successfully with percutaneous renal artery angioplasty; importantly, continuous 24-hr ambulatory monitoring after pressure gradient guided renal angioplasty confirmed reduction in blood pressure.

Blood-brain barrier compromise does not predict perihematoma edema growth in intracerebral hemorrhage

BACKGROUND AND PURPOSE

There are limited data on the extent of blood-brain barrier (BBB) compromise in acute intracerebral hemorrhage patients. We tested the hypotheses that BBB compromise measured with permeability-surface area product (PS) is increased in the perihematoma region and predicts perihematoma edema growth in acute intracerebral hemorrhage patients.

METHODS

Patients were randomized within 24 hours of symptom onset to a systolic blood pressure (SBP) treatment of <150 (n=26) or <180 mm Hg (n=27). Permeability maps were generated using computed tomographic perfusion source data acquired 2 hours after randomization, and mean PS was measured in the hematoma, perihematoma, and hemispheric regions. Hematoma and edema volumes were measured on noncontrast computed tomographic scans obtained at baseline, 2 hours and 24 hours after randomization.

RESULTS

Patients were randomized at a median (interquartile range) time of 9.3 hours (14.1) from symptom onset. Treatment groups were balanced with respect to baseline SBP and hematoma volume. Perihematoma PS (5.1±2.4 mL/100 mL per minute) was higher than PS in contralateral regions (3.6±1.7 mL/100 mL per minute; P<0.001). Relative edema growth (0-24 hours) was not predicted by perihematoma PS (β=-0.192 [-0.06 to 0.01]) or SBP change (β=-0.092 [-0.002 to 0.001]). SBP was lower in the <150 target group (139.2±22.1 mm Hg) than in the <180 group (159.7±12.3 mm Hg; P<0.0001). Perihematoma PS was not different between groups (4.9±2.4 mL/100 mL per minute for the <150 group, 5.3±2.4 mL/100 mL per minute for the <180 group; P=0.51).

CONCLUSIONS

BBB permeability is focally increased in the hematoma and perihematoma regions of acute intracerebral hemorrhage patients. BBB compromise does not predict acute perihematoma edema volume or edema growth. SBP reduction does not affect BBB permeability.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00963976.

Acute blood pressure reduction in patients with intracerebral hemorrhage does not result in borderzone region hypoperfusion

BACKGROUND AND PURPOSE

The Intracerebral Hemorrhage Acutely Decreasing Arterial Pressure Trial (ICH ADAPT) demonstrated blood pressure (BP) reduction does not affect mean perihematoma or hemispheric cerebral blood flow. Nonetheless, portions of the perihematoma and borderzones may reach ischemic thresholds after BP reduction. We tested the hypothesis that BP reduction after intracerebral hemorrhage results in increased critically hypoperfused tissue volumes.

METHODS

Patients with Intracerebral hemorrhage were randomized to a target systolic BP (SBP) of <150 or <180 mm Hg and imaged with computed tomographic perfusion 2 hours later. The volumes of tissue below cerebral blood flow thresholds for ischemia (<18 mL/100 g/min) and infarction (<12 mL/100 g/min) were calculated as a percentage of the total volume within the internal and external borderzones and the perihematoma region.

RESULTS

Seventy-five patients with intracerebral hemorrhage were randomized a median (interquartile range) of 7.8 (13.3) hours from onset. Acute hematoma volume was 17.8 (27.1) mL and mean SBP was 183±22 mm Hg. At the time of computed tomographic perfusion (2.3 [1.0] hours after randomization), SBP was lower in the <150 mm Hg (n=37; 140±18 mm Hg) than in the <180 mm Hg group (n=36; 162±12 mm Hg; P<0.001). BP treatment did not affect the percentage of total borderzone tissue with cerebral blood flow<18 (14.7±13.6 versus 15.6±13.7%; P=0.78) or <12 mL/100 g/min (5.1±5.1 versus 5.8±6.8%; P=0.62). Similar results were found in the perihematoma region. Low SBP load (fraction of time with SBP<150 mmHg) did not predict borderzone tissue volume with cerebral blood flow<18 mL/100 g/min (β=0.023 [-0.073, 0.119]).

CONCLUSIONS

BP reduction does not increase the volume of critically hypoperfused borderzone or perihematoma tissue. These data support the safety of early BP reduction in intracerebral hemorrhage.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00963976.

Clinical utility of ambulatory blood pressure monitoring in the management of hypertension

Accurate blood pressure (BP) measurement is essential for the diagnosis, monitoring and management of hypertension. However, conventional office-based BP readings have several limitations that include a low reproducibility, the white-coat effect and the existence of masked hypertension. These limitations can be addressed through the use of ambulatory BP monitoring. Because ambulatory monitoring provides measurements at specific time intervals throughout a 24-hour period, this technique represents a better picture of the normal fluctuations in BP levels associated with daily activities and sleep. In addition, end-organ damage associated with hypertension is more closely related to ambulatory BP than office BP measurements and ambulatory BP profile give better prediction of clinical outcome than conventional BP measurements.

Blood pressure load does not add to ambulatory blood pressure level for cardiovascular risk stratification

Experts proposed blood pressure (BP) load derived from 24-hour ambulatory BP recordings as a more accurate predictor of outcome than level, in particular in normotensive people. We analyzed 8711 subjects (mean age, 54.8 years; 47.0% women) randomly recruited from 10 populations. We expressed BP load as percentage (%) of systolic/diastolic readings ≥135/≥85 mm Hg and ≥120/≥70 mm Hg during day and night, respectively, or as the area under the BP curve (mm Hg×h) using the same ceiling values. During a period of 10.7 years (median), 1284 participants died and 1109 experienced a fatal or nonfatal cardiovascular end point. In multivariable-adjusted models, the risk of cardiovascular complications gradually increased across deciles of BP level and load (P<0.001), but BP load did not substantially refine risk prediction based on 24-hour systolic or diastolic BP level (generalized R(2) statistic ≤0.294%; net reclassification improvement ≤0.28%; integrated discrimination improvement ≤0.001%). Systolic/diastolic BP load of 40.0/42.3% or 91.8/73.6 mm Hg×h conferred a 10-year risk of a composite cardiovascular end point similar to a 24-hour systolic/diastolic BP of 130/80 mm Hg. In analyses dichotomized according to these thresholds, increased BP load did not refine risk prediction in the whole study population (R(2)≤0.051) or in untreated participants with 24-hour ambulatory normotension (R(2)≤0.034). In conclusion, BP load does not improve risk stratification based on 24-hour BP level. This also applies to subjects with normal 24-hour BP for whom BP load was proposed to be particularly useful in risk stratification.

Mobile personal health system for ambulatory blood pressure monitoring

The ARVmobile v1.0 is a multiplatform mobile personal health monitor (PHM) application for ambulatory blood pressure (ABP) monitoring that has the potential to aid in the acquisition and analysis of detailed profile of ABP and heart rate (HR), improve the early detection and intervention of hypertension, and detect potential abnormal BP and HR levels for timely medical feedback. The PHM system consisted of ABP sensor to detect BP and HR signals and smartphone as receiver to collect the transmitted digital data and process them to provide immediate personalized information to the user. Android and Blackberry platforms were developed to detect and alert of potential abnormal values, offer friendly graphical user interface for elderly people, and provide feedback to professional healthcare providers via e-mail. ABP data were obtained from twenty-one healthy individuals (>51 years) to test the utility of the PHM application. The ARVmobile v1.0 was able to reliably receive and process the ABP readings from the volunteers. The preliminary results demonstrate that the ARVmobile 1.0 application could be used to perform a detailed profile of ABP and HR in an ordinary daily life environment, bedsides of estimating potential diagnostic thresholds of abnormal BP variability measured as average real variability.

Impact of blood pressure changes and course on hematoma growth in acute intracerebral hemorrhage

BACKGROUND AND PURPOSE

An association between high blood pressure (BP) in acute intracerebral hemorrhage (ICH) and hematoma growth (HG) has not been clearly demonstrated. Therefore, the impact of BP changes and course on HG and clinical outcome in patients with acute ICH was determined.

METHODS

In total, 117 consecutive patients with acute (<6 h) supratentorial ICH underwent baseline and 24-h CT scans, CT angiography for the detection of the spot sign and non-invasive BP monitoring at 15-min intervals over the first 24 h. Maximum and minimum BP, maximum BP increase and drop from baseline, and BP variability values from systolic BP (SBP), diastolic BP and mean arterial pressure (MAP) were calculated. SBP and MAP loads were defined as the proportion of readings >180 and >130 mmHg, respectively. HG (>33% or >6 ml), early neurological deterioration (END) and 3-month mortality were recorded.

RESULTS

Baseline BP variables were unrelated to either HG or clinical outcome. Conversely, SBP 180-load independently predicted HG (odds ratio 1.05, 95% CI 1.010-1.097, P = 0.016), whilst both SBP 180-load (odds ratio 1.04, 95% CI 1.001-1.076, P = 0.042) and SBP variability (odds ratio 1.2, 95% CI 1.047-1.380, P = 0.009) independently predicted END. Although none of the BP monitoring variables was associated with HG in the spot-sign-positive group, higher maximum BP increases from baseline and higher SBP and MAP loads were significantly related to HG in the spot-sign-negative group.

CONCLUSIONS

In patients with acute supratentorial ICH, SBP 180-load independently predicts HG, whilst both SBP 180-load and SBP variability predict END.

A randomized, double-blind, placebo-controlled crossover study of coenzyme Q10 therapy in hypertensive patients with the metabolic syndrome

BACKGROUND

Our aim was to examine the effects of adjunctive coenzyme Q(10) therapy on 24-h ambulatory blood pressure (BP) in subjects with the metabolic syndrome and inadequate BP control.

METHODS

In a randomized, double-blind, placebo-controlled 12-week crossover trial, coenzyme Q(10) (100 mg twice daily) or placebo was administrated to 30 subjects with the metabolic syndrome, and inadequate BP control (an average clinic BP of ≥140 systolic mm Hg or ≥130 mm Hg for patients with type 2 diabetes) while taking an unchanged, conventional antihypertensive regimen. Clinic and 24-h ambulatory BP were assessed pre- and post-treatment phases. The primary outcomes were the changes in 24-h systolic and diastolic BP during adjunctive therapy with coenzyme Q(10) vs. placebo and prespecified secondary outcomes included changes in BP loads.

RESULTS

Compared with placebo, treatment with coenzyme Q(10) was not associated with statistically significant reductions in systolic (P = 0.60) or diastolic 24-h ambulatory BP (P = 0.12) or heart rate (P = 0.10), although daytime diastolic BP loads, were significantly lower during coenzyme Q(10) administration with thresholds set at >90 mm Hg (P = 0.007) and ≥85 mm Hg (P = 0.03). Coenzyme Q(10) was well tolerated and was not associated with any clinically relevant changes in safety parameters.

CONCLUSIONS

Although it is possible that coenzyme Q(10) may improve BP control under some circumstances, any effects are likely to be smaller than reported in previous meta-analyses. Furthermore, our data suggest that coenzyme Q(10) is not currently indicated as adjunctive antihypertensive treatment for patients with the metabolic syndrome whose BP control is inadequate, despite regular antihypertensive therapy.

Genetic influences on 24 h blood pressure profiles in a hypertensive population: role of the angiotensin-converting enzyme insertion/deletion and angiotensin II type 1 receptor A1166C gene polymorphisms

OBJECTIVE

Data on the association of the ACE I/D and AT1R A1166C polymorphisms with hypertension are conflicting. Most studies, however, have focused on office blood pressure (BP) only. The objective of the present study was to investigate the association of BP with the angiotensin-converting enzyme insertion/deletion (ACE I/D) and angiotensin II type 1 receptor A1166C (AT1R A1166C) polymorphisms by means of both office and ambulatory blood pressure monitoring (ABPM).

METHODS AND RESULTS

A total of 348 hypertensive patients participated in this study. Office BP did not differ between the various ACE or AT1R genotype groups. However, ambulatory BP and BP load were positively associated with the ACE I/D polymorphism. This was more apparent in men than in women. There were no differences in heart rate, BP variability, and amount of dipping. The AT1R A1166C polymorphism showed no consistent association with blood pressure (load).

CONCLUSION

From these data we conclude that frequent measuring of blood pressure by ABPM is crucial to find an association of the ACE D allele with various aspects of blood pressure.

Effects of angiotensin-converting enzyme gene polymorphism and serum vitamin D levels on ambulatory blood pressure measurement and left ventricular mass in Turkish hypertensive population

INTRODUCTION

Regulation of angiotensin converting enzyme (ACE) and angiotensin II (ang-II) levels is under genetic control. 1,25(OH)2 vitamin D3 treatment has been shown to reduce the ang-II level, reduce myocardial hypertrophy and to decrease blood pressure. This study was designed to examine the effect of ACE gene polymorphisms on 24-h ambulatory blood pressure measurement (24 h) values, vitamin D levels and target organ damage in hypertensive patients.

METHODS

This study was carried on 118 patients with essential hypertension (female/male: 70/48, mean age: 49.1+/-7.6 years, hypertension duration: 56+/-40.5 months). All patients were assessed for target organ damage; the eye by retinal examination, the heart with echocardiography and the kidney with blood and 24-h urine analysis. 24-h ambulatory blood pressure measurement was performed in all patients. PCR amplification was employed to detect ACE genotypes.

RESULTS

ACE genotypes were as follows: DD (n=49) 41.5%; ID (n=37) 31.4% and II (n=32) 27.1%. No difference was present between groups of ACE polymorphism when 24-h ambulatory blood pressure measurement values, retinal vascular changes and microalbuminuria were taken into account. Statistically significant left ventricular mass index levels were obtained in the DD group when compared with the non-DD (ID+II) group (P : 0.009). Positive correlations have been noted between left ventricular mass index and day/night and early morning systolic pressures. A negative correlation exists between serum 25 (OH) vitamin D levels and 24-h ambulatory blood pressure measurement values (P<0.05).

CONCLUSIONS

The presence of the D allele is linked with a higher risk for left ventricular mass index in the Turkish hypertensive population.

Utility of ambulatory blood pressure monitoring in children and adolescents

Diagnosis of hypertension is critically dependent on accurate blood pressure measurement. "Accurate" refers to carefully following the guidelines for blood pressure measurement laid out for children and adults to minimize observer and subject errors that commonly occur in clinical blood pressure measurement. Accurate blood pressure measurement is more important in children and adolescents as the misdiagnosis of hypertension may have a life-long adverse impact on insurability and employment. Automated blood pressure measurement offers multiple advantages in achieving high-quality blood pressure determinations by reducing observer errors. The most commonly used form of automated blood pressure measurement is 24-h ambulatory blood pressure measurement (ABPM). Information on ABPM in children has grown exponentially over the last decade. Normative data exists for diagnosis of hypertension in children using ABPM including a novel method for determining normal values with the LMS method. There is further information about the utility of different determinants of 24-h blood pressure such as dipping status, morning surge and blood pressure load. ABPM has been able to detect significant differences in blood pressure in many disease states in children including chronic renal failure, polycystic kidney disease, solitary functioning kidney, and after renal transplantation. Increasingly nonambulatory automated blood pressure determinations have been used in management of hypertension in children. Although nonambulatory automated readings lack information about nocturnal blood pressure or blood pressure during daily activity, studies have suggested that home automated blood pressure measurements are a helpful adjunct to the usual office blood pressure reading.

Is the area under blood pressure curve the best parameter to evaluate 24-h ambulatory blood pressure monitoring data?

BACKGROUND

Ambulatory blood pressure monitoring (ABPM) provides relevant data about blood pressure over a 24-h period. The analysis of parameters to determine the blood pressure profile from these data is of great importance.

OBJECTIVES

To calculate areas under systolic and diastolic blood pressure curves (SBP-AUC/DBP-AUC) and compare with systolic and diastolic blood pressure load (SBPL/DBPL) and 24-h systolic and diastolic blood pressure (24-h SBP/24-h DBP) in order to determine which provides the best correlation with left ventricular mass index (LVMI).

METHODS

ABPM measurements (1143 individuals) were analyzed to obtain 24-h SBP/24-h DBP, SBPL/DBPL, and SBP-AUC/ DBP-AUC, using Spacelabs (90207) and CardioSistemas devices. Left ventricular mass was determined using an echocardiograph HP Sonos 5500 and LVMI was calculated.

RESULTS

The correlations between all possible pairs within the group 24-h SBP/SBPL/SBP-AUC and 24-h DBP/DBPL/DBP-AUC were high and statistically significant. The correlations between 24-h SBP/24-h DBP and SBP-AUC/DBP-AUC with SBPL/DBPL close to 100%, were lower than those mentioned above. The correlations of the parameters obtained by ABPM with LVMI were also high and statistically significant, except for blood pressure load between 90 and 100%, and for 24-h SBP of 135 mmHg or less and SBPL higher than 50%.

CONCLUSIONS

SBPL/DBPL and SBP-AUC/DBP-AUC can be used for the evaluation of ABPM data owing to the strong correlation with 24-h SBP/24-h DBP and with LVMI, except when SBPL is close to 100% or 24-h SBP is below 135 mmHg but SBPL is above 50%. SBP-AUC/DBP-AUC, however, are a better alternative because they do not have the limitations of blood pressure load or even of 24-h blood pressure present.

Ambulatory blood pressure monitoring

Noninvasive, 24-hour ambulatory blood pressure monitoring (ABPM) has evolved over the past 25 years from a novel research tool of limited clinical use into an important and useful modality for stratifying cardiovascular risk and guiding therapeutic decisions. Early clinical uses of ABPM were mostly focused on identifying patients with white-coat hypertension; however, accumulated evidence now points to greater prognostic significance in determining risk for hypertensive end-organ damage compared with office blood pressure measurements. Ambulatory measurement of blood pressure using automated devices has also demonstrated benefit in other indications, such as treatment resistance and borderline hypertension, and is recommended by the Joint National Committee for the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure in a number of clinical scenarios. Medicare recently announced plans to begin reimbursement for ABPM, which will likely increase demand for ABPM services. Clinicians should become familiar with the role of this technology in the care of the hypertensive patient.

Restoration of nocturnal dip in blood pressure is associated with improvement in left ventricular ejection fraction. A 1-year clinical study comparing the effects of amlodipine and nifedipine retard on ambulatory blood pressure and left ventricular systolic function in Chinese hypertensive type 2 diabetic patients

We assessed the effects of amlodipine and nifedipine retard on 24-h blood pressure (BP) control, nocturnal fall in BP and their significance on left ventricular systolic functions in 54 Chinese hypertensive type 2 diabetic patients. Patients being recruited were openly randomised to amlodipine or nifedipine retard. Ambulatory 24-h BP and echocardiogram (in 42 patients) were measured before and 1 year after treatment. At the end of study, there was 17% reduction in systolic BP; 17% reduction in diastolic BP and 12% reduction in mean arterial pressure (MAP) (no difference between amlodipine and nifedipine). Of the 42 subjects underwent echocardiograms, eight became 'new-dippers' at the end of study (non-dippers before treatment and restored nocturnal fall of MAP> or =10% after treatment). The other 34 patients were either non-dippers before and after treatment (n=27); dippers before and after treatment (n=3) or dippers before treatment and non-dippers after treatment (n=4). The eight 'new-dippers' had improved ejection fraction (69.6+/-7.2 to 75.8+/-7.4%, P<0.05) and increased left ventricular diastolic diameter (43.7+/-7.9 to 47.9+/-8.8 mm, P<0.05) after the 1-year treatment of calcium antagonist. Compared to the other 34 subjects, the eight 'new-dippers' showed significant improvement in ejection fraction (9.4+/-10.9 vs. -1.2+/-11.8%, P<0.05). In conclusion, both amlodipine and nifedipine retard are effective in controlling the 24-h BP in Chinese hypertensive type 2 diabetic patients. For those who have restored nocturnal dip in BP have significantly increased left ventricular systolic ejection fraction after 1-year treatment of long acting calcium antagonists. The clinical significance and underlying mechanisms require further studies.

The tolerance-hyperbaric test: a chronobiologic approach for improved diagnosis of hypertension

Blood pressure (BP) displays predictable large-amplitude circadian variability. Thus, the identification and the proper definition of hypertension are highly ambiguous when based on single time-unspecified measurements. One way to deal with such variability in the diagnosis of hypertension is to replace the commonly used constant limits of BP by a time-specified reference interval based on the normal circadian BP rhythm assessed by ambulatory BP monitoring (ABPM). A proper reference limit can be constructed, for instance, as a tolerance interval computed for every specific time interval throughout the 24 h. Once such a threshold (given by the upper limit of the tolerance interval) is constructed, a hyperbaric index (HBI) can be computed by numerical integration of the total area of any given patient's BP profile above threshold. The HBI plus the duration of excess within the 24h day serves as nonparametric endpoints for assessing hypertension. Both retrospective and prospective evaluation of this tolerance-hyperbaric test validate its high sensitivity and specificity in the diagnosis of hypertension. We describe the theory of the HBI as well as a newly created dedicated software program that automatically derives the tolerance intervals from a reference database of normotensive subjects and calculates the HBI and other potentially valuable parameters based on data obtained by ABPM. The establishment of time-qualified tolerance limits and the assessment of the extent and timing of BP elevation represents a valuable tool for the more accurate diagnosis of hypertension as well as means of gauging response to treatment.

Ambulatory blood pressure monitoring in children and adolescents

With recent technological advances, 24-hour ambulatory blood pressure (BP) monitoring (ABPM) has become a useful tool for the evaluation, diagnosis, and management of hypertensive children. It provides a more accurate representation of an individual's BP rather than intermittent casual or office BP measurements. Hence, ABPM is being used more often to assess the BP of children. In this comprehensive review, we provide the reader with the available literature on ABPM, discuss the advantages and limitations of ABPM, and the interpretation of ABPM data. The role of ABPM in various clinical conditions and hypertension research in children is presented.

Circadian pattern of blood pressure, heart rate, and double product in liver glycogen storage disease

The objective of this study was to determine systolic, diastolic, and mean arterial blood pressure (SBP, DBP, and MAP), heart rate (HR), double-product (DP: SBP x HR), and activity levels and their 24h pattern in liver glycogen storage disease (LGSD) patients. A case series of 12 (11 pediatric and one adult) diurnally active LGSD (seven type I, three type III, and two type IX) subjects were simultaneously assessed by 24h ambulatory blood pressure monitoring and wrist actigraphy. Nine subjects were judged to be hypertensive based on the criterion of an elevated 24h mean SBP and/or DBP being elevated beyond reference standards or the SBP and/or DBP load (percentage of time BP exceeds normal values) being greater than 25%. Two of the three other subjects, not viewed as hypertensive based on their 24h average SBP or DBP, exhibited daytime or nighttime SBP and/or DBP load hypertension. Each study variables displayed statistically significant (p < 0.001) group circadian rhythmicity. The SBP, DBP, and MAP displayed comparable 24h patterns of appreciable amplitude (total peak-trough variation equal to 17.7, 23.6, and 19.6%, respectively, of the 24h mean) with highest values (orthophase) occurring approximately 11 h after the commencement of daytime activity. The sleep-time trough (bathyphase) occurred approximately 4.5 h before morning awakening. The statistically significant (p < 0.006) circadian rhythms of HR (amplitude equal to 33.2% of the 24h mean) and DP (amplitude equal to 49.4% of the 24h mean) peaked earlier, approximately 7.4 h into the daytime activity span. The sleep-time trough occurred approximately 3 h before morning awakening. The 24h pattern in the cardiovascular variables was correlated with the 24h pattern of activity, with r ranging from 0.50 for DBP to 0.39 for HR.

Noninvasive 24-hour ambulatory blood pressure monitoring: overview of technology and clinical applications

During the last 25 years, 24-hour noninvasive ambulatory blood pressure monitoring (ABPM) has evolved from a research tool of limited clinical use into an important tool for stratifying cardiovascular risk and guiding therapeutic decisions. Until recently, clinical use of ABPM focused on identifying patients with white-coat hypertension, but accumulated evidence now points to greater prognostic significance of ABPM in determining risk for target-organ damage compared with that of office blood pressure measurements. Clinicians involved in the care of patients with hypertension should familiarize themselves with the role of this technology and how to use it in an appropriate and cost-effective manner.

Modeling the circadian variability of ambulatorily monitored blood pressure by multiple-component analysis

The use of a set of new end points derived from ambulatory blood pressure monitoring (ABPM), in addition to the blood pressure (BP) values themselves, has been advocated to improve the sensitivity and specificity in diagnosing hypertension and to evaluate a person's response to treatment. An adequate estimation of rhythmic parameters depends, however, on the ability to describe properly the circadian pattern of BP variability. The purpose of this study was to identify a simple model that could characterize sufficiently well the circadian pattern of BP in normotensive healthy volunteers sampled by ambulatory monitoring. We studied 278 clinically healthy Spanish adults (184 men), 22.7 +/- 3.3 yr of age, without medical history of hypertension and mean BP from ambulatory profiles always below 135/85 mmHg for systolic/diastolic BP, who underwent sequential ABPM providing a total of 1115 series of BPs and heart rates (HRs), sampled on each occasion at 0.5h intervals for 48 h. Subjects were assessed while adhering to their usual diurnal activity and nocturnal sleep routine, without restrictions but avoiding the use of medication. The circadian rhythm in BP and HR for each subject was established by multiple-component analysis. A statistically significant 24h component is documented for 97% of the BP profiles, with a significant second (12h) harmonic documented in 65% of the profiles. Other ultradian harmonic components were significant in less than 20% of the profiles. A statistically significant increase in the coefficient of determination (percent of overall variability explained by the function fitted to the data) was only obtained after including the periods of 24 and 12 h for BP, and periods of 24, 12, and 6 h for HR in the model components. Although other ultradian components can be demonstrated as statistically significant in a small percent of subjects, a rather simple model including only the two first harmonics of the 24h period describes sufficiently well, at the specified sampling rate, the circadian pattern of BP in normotensive subjects. Departure from this model could characterize overt pathology, as recently demonstrated in the diagnosis of preeclampsia.

Evaluation of the blood pressure load in the diagnosis of hypertension in pregnancy

The use of a set of new end points obtained from ambulatory blood pressure monitoring, in addition to the blood pressure values themselves, has been advocated to improve sensitivity and specificity in the diagnosis of hypertension and the evaluation of a patient's response to treatment. Among these parameters is the use of blood pressure load, the percentage of values above a given constant reference limit or computed by reference to daytime and nighttime limits. We examined the effectiveness of this parameter as a potential screening test for the detection of hypertension in pregnancy. We analyzed 2014 blood pressure series systematically sampled by ambulatory monitoring for 48 consecutive hours every 4 weeks from the first obstetric visit (usually within the first trimester of pregnancy) until delivery of 205 normotensive pregnant women and 123 women who developed gestational hypertension or preeclampsia. The blood pressure load was obtained as the percentage of values >140/110/90 mm Hg (systolic/mean arterial/diastolic blood pressure) during active hours or 120/95/80 mm Hg during resting hours, as well as by comparison with limits obtained by progressively reducing the previous limits by 5 mm Hg, up to a final threshold of 125/95/75 mm Hg (day) and 105/80/65 mm Hg (night). Sensitivity for the blood pressure load computed by reference to the highest limits used here is <55% in all trimesters of pregnancy. The best results were obtained when 130/100/80 mm Hg (day) and 110/85/70 mm Hg (night) were used as references in the third trimester, and when the lowest tested limits of 125/95/75 and 105/80/65 mm Hg were used as references in the first and second trimesters (sensitivity always >73%). The optimum reference limits for calculating the blood pressure load, markedly < mm Hg, must be defined as a function of gestational age, in keeping with the predictable trends in blood pressure along pregnancy previously documented.

Determination of ambulatory blood pressure control in treated patients with controlled office blood pressures

Office blood pressure measurement is the standard for assessing blood pressure control. Many patients, however, take their antihypertensive medication in the morning, so they are likely to have their office blood pressure measured during the maximal antihypertensive effect. It is therefore unknown whether patients deemed by office blood pressure to be controlled do in fact have 24h blood pressure control. The objectives of this study were to determine blood pressure control, including blood pressure control while the patients were awake and during the first 6 hours after awakening, by ambulatory blood pressure monitoring (ABPM) in treated hypertensive patients deemed by office blood pressure measurements to be controlled. A total of 103 patients on a stable antihypertensive regimen and deemed to be controlled in terms of office blood pressure values (mean office blood pressure <140/90mmHg) were enrolled. Patients were stratified by cardiovascular risk status and the number of antihypertensive medications that they were taking. Seventy-eight out of 103 participants successfully completed ABPM. The mean ambulatory blood pressure was greater than 135/85mmHg and 140/90mmHg while awake for 37% (95% confidence interval [CI] 26-48%) and 23% (95% CI 14-32%) of all patients respectively. Forty-eight per cent (95% CI 33-63%) of patients taking monotherapy versus 25% (95% CI 11-39%) of patients on multiple antihypertensive medications were uncontrolled (P=0.039) using 135/85mmHg as the reference value. Thirty-one per cent (95% CI, 17-44%) of patients on monotherapy versus 14% (95% CI 3-25%) of patients on multiple antihypertensive medication were uncontrolled (P=0.064) using 140/90mmHg instead. These results demonstrate that a high number of patients deemed by office blood pressure to be under control do not have adequate blood pressure control based on ABPM.

Computation of model-dependent tolerance bands for ambulatorily monitored blood pressure

The construction of time-specified reference limits requires systematic sampling in clinical health, particularly for those variables characterized by a circadian rhythm of large amplitude, as it is the case for blood pressure (BP). For the detection of false negatives, tolerance intervals (limits that will include at least a specified proportion of the population with a stated confidence) are important and should substitute when possible for prediction limits. We have previously described a nonparametric method for the computation of model-independent tolerance intervals that are constructed by first dividing the sampling range in several time spans in which no appreciable changes in population characteristics (namely, mean and variance) take place. The tolerance interval is then computed for each of the time spans. The limits thus computed, as well as results of any comparison of a given individual's profile against such tolerance intervals, are highly dependent on the sampling scheme of both the reference individuals and the test subject. To avoid this problem, we have developed an alternative method that allows the computation of model-dependent tolerance bands for hybrid time series. Assuming that a set X of longitudinal series monitored from a given group of reference individuals can be fitted with the same individual model, a population model C(X,t) can be also determined, as well as the deviation S(X,t) of each individual curve from the population model. The tolerance band will then have the form C(X,t) +/- kS(X,t), where k is here estimated following a nonparametric approach based on bootstrap techniques. Alternatively, two different values of k can be estimated (for the lower and upper limits of the tolerance interval, respectively) in cases for which we cannot assume symmetry. The method is generally applicable for any population model describing the reference population (including the fit of multiple significant components, nonsinusoidal waveforms, and/or trends). The method was used to establish time-specified tolerance bands for time series of blood pressure monitored automatically in healthy individuals of both genders. Model-dependent intervals are preferred to the model-independent limits when reliance on a specified sampling rate needs to be avoided. These limits may serve for an objective and positive definition of health, for the screening and diagnosis of disease, and for gauging the subject's response to treatment.

Cardiovascular effects of melatonin in hypertensive patients well controlled by nifedipine: a 24-hour study

AIMS

As melatonin has been found to play a role in the mechanisms of cardiovascular regulation, we designed the present study to evaluate whether the evening ingestion of the pineal hormone might interfere with the antihypertensive therapy in hypertensive patients well-controlled by nifedipine monotherapy.

METHODS

Forty-seven mild to moderate essential hypertensive outpatients taking nifedipine GITS 30 or 60 mg monotherapy at 08.30 h for at least 3 months, were given placebo or melatonin 5 mg at 22.30 h for 4 weeks according to a double-blind cross-over study. At the end of each treatment period patients underwent a 24 h noninvasive ambulatory blood pressure monitoring (ABPM) during usual working days; sleeping period was scheduled to last from 23.00 to 07.00 h.

RESULTS

The evening administration of melatonin induced an increase of blood pressure and heart rate throughout the 24 h period (DeltaSBP = + 6.5 mmHg, P < 0.001; DeltaDBP = + 4.9 mmHg, P < 0.01; DeltaHR = + 3.9 beats min-1, P < 0.01). The DBP as well as the HR increase were particularly evident during the morning and the afternoon hours.

CONCLUSIONS

We hypothesize that competition between melatonin and nifedipine, is able to impair the antihypertensive efficacy of the calcium channel blocker. This suggests caution in uncontrolled use of melatonin in hypertensive patients. As the pineal hormone might interfere with calcium channel blocker therapy, it cannot be considered simply a dietary supplement.

Reproducibility of the hyperbaric index as a measure of blood pressure excess

The approach of establishing a time-specified tolerance limit reflecting the circadian variability in blood pressure and then determining the hyperbaric index, the area of blood pressure excess above the upper limit of the tolerance interval, has been proposed for diagnosing hypertension as well as for evaluating the patient's response to treatment. The retrospective evaluation of this test provided high sensitivity and specificity in the diagnosis of hypertension, with a threshold value for the hyperbaric index of 15 mm Hg. h. To evaluate the stability and reproducibility of this tolerance-hyperbaric test, we studied 332 previously untreated subjects (218 men) who underwent sequential 48-hour ambulatory blood pressure monitoring for 2 years, providing a total of 1337 blood pressure profiles. Diagnosis of hypertension was established for each subject on the restricted basis of presenting at least 1 blood pressure profile with a hyperbaric index above the previously defined threshold. Sensitivity of this tolerance-hyperbaric test was 98.6%, with a negative predictive value of 99.7%. For the same subjects, the blood pressure load (percentage of values >140/110/90 mm Hg for systolic/mean arterial/diastolic blood pressure during activity or >120/95/80 mm Hg during resting hours) had a sensitivity of 49% and specificity of 25%. The 24-hour mean, still the most common approach for diagnosing hypertension on the basis of ambulatory monitoring, had sensitivities of 40% and 31% for systolic and diastolic blood pressure, respectively. Despite the limitations of ambulatory blood pressure monitoring, the tolerance-hyperbaric test represents a reproducible, noninvasive, and high-sensitivity test for the identification of subjects in need of prophylactic or therapeutic intervention.

Twenty-four-hour blood pressure profile and blood pressure responses to head-up tilt tests in Parkinson's disease and multiple system atrophy

OBJECTIVE

To investigate the 24 h blood pressure profile in patients with Parkinson's disease with intact autonomic function or with autonomic failure and patients with multiple system atrophy (MSA), and to assess whether these patients exhibit posture-related variations in blood pressure.

PATIENTS AND METHODS

We studied 24 patients with Parkinson's disease (11 with autonomic failure) and 13 patients with MSA (all with autonomic failure). Autonomic failure was determined by autonomic tests. An oscillometric recorder was used for ambulatory blood pressure monitoring. Tilt-table tests were performed with a head-up tilt position of 60 degrees.

RESULTS

An alteration in the normal 24 h blood pressure profile was observed in 82% of Parkinson's disease patients with autonomic failure and in 85% of those with multiple system atrophy, but not in the patients with intact autonomic function. Head-up tilt tests revealed a significantly higher supine blood pressure in Parkinson's disease patients with autonomic failure and in those with MSA than in Parkinson's disease patients with intact autonomic function. Tilting resulted in a marked fall in blood pressure in patients with MSA; in Parkinson's disease patients with autonomic failure, the fall was comparatively slighter.

CONCLUSIONS

We conclude that autonomic failure contributes to the alterations in the day-night blood pressure profile that may possibly be ascribed to postural dysregulation of blood pressure. We hypothesize that nocturnal hypertension is a risk factor in the development of additional cerebrovascular disease in patients with Parkinson's disease or MSA who are affected by autonomic failure.

Blood pressure excess for the early identification of gestational hypertension and preeclampsia

We have examined prospectively whether the combined approach of establishing tolerance intervals for the circadian variability of blood pressure (BP) as a function of gestational age, and then determining the so-called hyperbaric index (area of BP excess above the upper limit of the tolerance interval) by comparison of any patient's BP profile (obtained by ambulatory monitoring) with those intervals provides a high sensitivity test for the early detection of pregnant women who subsequently will develop gestational hypertension or preeclampsia. We analyzed 657 BP series from 92 women with uncomplicated pregnancies and 378 series from 60 women who developed gestational hypertension or preeclampsia. BP was sampled for about 48 hours once every 4 weeks after the first obstetric consultation. Circadian 90% tolerance limits were determined as a function of trimester of gestation from 497 series previously sampled from a reference group of 189 normotensive pregnant women. The hyperbaric index was then determined for each individual BP series in the validation sample. Sensitivity of this test for diagnosing gestational hypertension was 93% for women sampled during the first trimester of gestation and increased up to 99% in the third trimester. The positive and negative predictive values were above 96% in all trimesters. Despite the limitations of ambulatory monitoring, the approach presented here, now validated prospectively, represents a reproducible, noninvasive, and high sensitivity test for the very early identification of subsequent gestational hypertension and preeclampsia, on the average, 23 weeks before the clinical confirmation of the disease.

Diagnosing gestational hypertension and preeclampsia with the 24-hour mean of blood pressure

The use of ambulatory blood pressure monitoring has provided a method of blood pressure assessment that may compensate for some of the limitations of isolated measurements. Here we aim to examine prospectively the effectiveness of the commonly used 24-hour mean as a potential screening test for the identification of gestational hypertension and preeclampsia. We analyzed 503 blood pressure series from 71 healthy pregnant women and 256 series from 42 women who developed gestational hypertension or preeclampsia. Forty-eight-hour blood pressure monitoring was done once every 4 weeks after the first obstetric consultation. Sensitivity and specificity of the 24-hour mean of blood pressure were computed for each trimester of pregnancy by comparing distributions of values obtained for healthy and complicated pregnancies, without assuming an a priori threshold for diagnosing gestational hypertension on the basis of mean blood pressure. Sensitivity ranges from 31.8% for diastolic blood pressure in the second trimester to 84.1% for systolic blood pressure in the third trimester. However, specificity is as low as 6.9% for diastolic blood pressure in the first trimester. The positive predictive value does not reach 55% for any variable in any trimester. The higher relative risk was consistently obtained for systolic blood pressure (4.9 in the third trimester). Despite the highly statistically significant differences in blood pressure found between healthy and complicated pregnancies in all trimesters, the daily mean of blood pressure does not provide a proper and stable individualized test for diagnosing hypertensive complications in pregnancy. Other indexes obtained from the blood pressure series have been shown, however, to identify early in pregnancy those women who subsequently will develop gestational hypertension or preeclampsia, rendering ambulatory blood pressure monitoring a useful, but still costly, technique in pregnancy.

Conflicting data on intervillous circulation in early pregnancy

According to classic embryological textbooks intervillous circulation is established early in the first trimester. This process starts with trophoblastic invasion of the decidua in which proteolytic enzymes facilitate the penetration and erosion of the adjacent maternal capillaries with formation of the lacunae. After the lacunar or previllous stage trophoblast invades deeper portions of endometrium with belonging spiral arteries. This gradual process finishes with direct opening of the spiral arteries in the intervillous space under the fully developed placenta. This classic concept of establishment of the intervillous circulation was challenged in 1987 and 1988 by the experiments of HUSTIN and SHAAPS. The authors believed that blood flow in the intervillous space is absent in incompletely development before 12 weeks of gestation. After the introduction of the new generation of far more sensitive color Doppler devices in the last few years, our group and several others reported a positive finding of intervillous circulation during the first trimester of pregnancy.