Ambulatory blood pressure monitoring

Hypertension and the Heart

The interactions linking high blood pressure with hypertensive heart disease are reciprocal. Hypertension can be regarded as a source of adverse effects on myocardial structure and function by favoring the development and progression of left ventricular hypertrophy and of left ventricular dysfunction and failure in the advanced phases of the disease. Conversely, the heart can be regarded as a source of reflex influences on the cardiovascular system, which appear to be deranged in the hypertensive state. The clinical relevance of this reflex dysfunction is based on the evidence that these alterations may favor the occurrence of an increased sympathetic vasoconstrictor drive, thereby promoting the development of the1 hypertensive state. Both phenomena have important clinic and therapeutic implications potentiating the cardiovascular risk profile of the hypertensive patient.

Psychosocial and physiological stress among women leaving welfare

Women receiving Temporary Assistance for Needy Families (TANF) report more stress and have poorer health than women in the general population. Studies suggest chronic stress may contribute to poor health via physiological mechanisms, yet little is known about these mechanisms in this population. This study examined psychosocial stress, salivary cortisol, 24-hr ambulatory blood pressure and heart rate, and health among 40 single mothers before and after exiting TANF. As a group, perceived stress decreased after leaving TANF (p = .02), with other measures of psychosocial and physiological stress remaining unchanged. Within participants, changes in psychosocial stress predicted depression and general health over time (adjusted R(2) = .30 and .22; p = .006 and .004, respectively). These findings indicate psychosocial stress is positively associated with depression and negatively associated with general health as women exit welfare. Psychosocial stress was not associated with changes in physiologic indicators of stress.

Reproducibility of dipping/nondipping pattern in untreated essential hypertensive patients: impact of sex and age

OBJECTIVE

We aimed to evaluate the intrasubject short-term reproducibility of nocturnal blood pressure patterns (dipping/nondipping) in essential hypertensive patients in relation to age (<50 and > or =50 years) and sex.

METHODS

A total of 619 never-treated essential grade 1 and 2 hypertensive patients (383 men, 236 women) underwent the following procedures: (1) repeated clinic blood pressure measurements, (2) routine examinations, (3) ambulatory blood pressure monitoring over two 24-h periods within 4 weeks. Dipping pattern was defined as a 10%, or more, reduction in average systolic blood pressure/ diastolic blood pressure at night compared to daytime values.

RESULTS

Of the 407 patients showing a dipping pattern during the first ambulatory blood pressure monitoring period, 329 (80.1%) had the same pattern during the second ambulatory blood pressure monitoring recording. Of the 212 patients with a nondipping pattern during the first ambulatory blood pressure monitoring period, 140 (65.9%) confirmed the same pattern during the second ambulatory blood pressure monitoring period. Overall, 149 patients (24.1%) changed their initial nocturnal pattern at the second ambulatory blood pressure monitoring recording, without significant age and sex-related differences. Lower reproducibility rates of the nondipping as compared to the dipping pattern were found in the whole population as well as in men regardless of age and in younger but not in older women.

CONCLUSIONS

These findings indicate that nocturnal blood pressure patterns have a limited short-term reproducibility in the whole study population as well as in different age and sex subgroups. As variability of nocturnal blood pressure patterns is not predicted by easy available clinical data, such as sex and age, a reliable classification of patients according to circadian blood pressure patterns should be obtained by repeating ambulatory blood pressure monitoring.

Laboratory, reading center, and coordinating center data management methods in the Jackson Heart Study

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in the United States. In comparison to whites, African-Americans have a higher risk of dying from CVD and have a worse risk factor profile. The Jackson Heart Study (JHS) is designed to investigate the origin and natural history of CVD in African-Americans.

METHODS

Reading centers for electrocardiograms, echocardiograms, carotid ultrasonograms, pulmonary function tests, and ambulatory blood pressure monitoring provide training for data accrual, quality assurance assessments, and specialized measurements for research objectives. Laboratories adhering to well-established quality assurance programs provide blood and urine analyses, as well as storage of specimens for future assays. A new Coordinating Center was created to perform functions analogous to those of coordinating centers for multisite studies, including protocol development, data management, statistical analyses, and operational support for the study. An established coordinating center serves as a resource to the JHS Coordinating Center, providing assistance in preparing procedure manuals and data collection forms. This group also designed and developed the JHS data management system.

RESULTS

This network of specialized research organizations is implementing state- of-the-science methodologies to assess prevalence, progression, and incidence of CVD and subclinical atherosclerosis, and to evaluate a myriad of risk factors. From November 2000 through March 2004, JHS collected 4000 data fields on each of more than 5300 African-American participants.

CONCLUSIONS

This article describes the roles of specialized research agencies contributing to JHS, and the methodologies being utilized to accumulate study data. A diverse collection of scientific disciplines is required to collect the information needed to meet the objectives of the JHS.

Reproducibility of nocturnal blood pressure fall in early phases of untreated essential hypertension: a prospective observational study

A number of studies have shown that a smaller than normal nocturnal blood pressure (BP) decrease is associated with cardiovascular disease. However, no large prospective studies have examined the reliability of nocturnal dipping within individuals. The aim of our study was to investigate the short-term variability of nocturnal BP fall in a large cohort of patients with recently diagnosed essential hypertension. In all, 414 uncomplicated never treated hypertensive patients referred to our outpatient hypertension hospital clinic (mean age 46+/-12 years; 257 M, 157 F) prospectively underwent: (1). repeated clinic BP measurements; (2). routine examinations recommended by WHO/ISH guidelines; and (3). ambulatory BP monitoring (ABPM) twice within a 4-week period. Dipping pattern was defined as a reduction in the average systolic and diastolic BP at night greater than 10% compared to average daytime values. Overall, 311 patients (75.1%) showed no change in their diurnal variations in BP. Of the 278 patients who had a dipping pattern on the first ABPM, 219 (78.7%) confirmed this type of profile on the second ABPM, while 59 (21.3%) showed a nondipping pattern. Among 37 dipper patients with >20% of nocturnal systolic BP decrease (extreme dippers), only 16 (43.2%) had this marked fall in BP on the second ABPM. Of the 136 patients who had a nondipping pattern on the first ABPM, 92 (67.6%) confirmed their initial profile on the second ABPM, while 44 (32.4%) did not. Patients with reproducible nondipping profile were older (48+/-12 years) than those with reproducible dipping profile (44+/-12 years, P<0.05). These findings indicate that: (1). short-term reproducibility of nocturnal fall in BP in untreated middle-aged hypertensives is rather limited: overall, one-fourth of patients changed their initial dipping patterns when they were studied again after a few weeks; (2). this was particularly true for extreme dipping and nondipping patterns; (3). abnormalities in nocturnal BP fall, assessed by a single ABPM, cannot be taken as independent predictors of increased cardiovascular risk.

Too much of a good thing? A critique of overemphasis on the use of ambulatory blood pressure monitoring in clinical practice

Ambulatory blood pressure monitoring (ABPM) can be considered a major achievement in clinical medicine. However, its superiority over traditional clinical measurement has often been overemphasized in the literature. In both cross-sectional and longitudinal studies, ABPM has been compared with clinical blood pressure calculated from only a few readings taken over a short period of time. For reasons of costs and practicality, ABPM should not be considered as a routine test in the assessment of the hypertensive patient. Most patients with borderline hypertension or isolated clinical hypertension can be profitably assessed with multiple clinical readings and self-blood pressure monitoring. Patients with large short-term or long-term blood pressure oscillations appear as optimal candidates to ABPM. The many methodological problems associated with the use of this technique suggest that ABPM is performed only by experienced doctors.

Night time blood pressure and cardiovascular structure in a middle-aged general population in northern Italy: the Vobarno Study

The aim was to determine, in a cross-sectional study, the relation between structural alterations in the heart and carotid arteries, and blood pressure (BP) changes from day to night time, measured by ambulatory BP (ABP). In 225 untreated subjects (107 F, 118 M, age range 48-64 years) and 59 treated subjects (24 M, 35 F, age range 50-64), living in a small town of northern Italy (Vobarno, Brescia) carotid intima media thickness as well as the occurrence of plaque, were evaluated by ultrasound. Echocardiographic left ventricular (LV) mass was measured according to the Penn Convention. BP was determined by clinic measurement and by 24-h non-invasive ABP monitoring. Subjects were divided in two groups, according to the decrease of night time systolic BP (SBP) "dippers" (SBP decreased by at least 10% during night time) and "non-dippers" (decrease of night time SBP <10%). The intima-media thickness in the common carotid, in the carotid bifurcation, in the internal carotid artery and average intima-media thickness were significantly greater in untreated non-dippers as compared with dipper subjects (ANOVA P < 0.05). A significantly higher prevalence of plaque was observed in untreated non-dippers as compared with dippers (P = 0.002). After adjusting for age, sex, 24-h SBP, and smoking, IMT in the carotid bifurcation and average intima-media thickness remained significantly greater in non-dipper subjects (P < 0.05 for all comparisons). No significant differences in LV mass were observed between dippers and non-dipper subjects. In conclusion, in a general population of unselected middle-aged subjects, night time BP values, among other risk factors, seem to represent an important determinant of carotid wall structure.

Defensiveness status predicts 3-year incidence of hypertension

OBJECTIVE

A growing body of research indicates that defensive personality styles (in particular, self-deception) may be related to higher resting blood pressure and stress reactivity levels. This study is the first, however, to examine the value of defensiveness as a prognostic indicator for the development of clinical hypertension.

METHODS

Participants were 127 initially normotensive male and female adults who completed a comprehensive protocol including psychological testing, assessment of smoking, physical activity and body fat levels, and 8-12 h ambulatory blood pressure monitoring. Participants returned 3-years later for an identical follow-up protocol. Defensiveness was assessed using the Balanced Inventory of Desirable Responding.

RESULTS

At 3-year testing, 15 of 127 participants (12%) met criteria for hypertension (i.e. ambulatory mean blood pressure > 140/90). Comparisons between defensiveness groups showed that 12 of 60 (20%) high defensiveness participants met hypertension criteria, whereas only three of 67 (4.5%) low defensiveness participants were hypertensive. Logistic regression equations adjusted for age, alcohol usage, bodyfat, self-reported exercise levels, smoking, and year-1 ambulatory blood pressure, revealed that membership in the high defensiveness group was associated with more than a sevenfold risk of 3-year hypertension (adjusted risk ratio, 7.5; 95% confidence interval, 1.5-39.2).

CONCLUSIONS

These findings link defensive characteristics to an increased prospective risk of hypertension using state of the art ambulatory monitoring techniques, and were robust after controlling for established risk factors. We conclude that the current results add to the hypertension literature by demonstrating associations between personality and clinically relevant blood pressure criteria.

Factors underlying the increase in carotid intima-media thickness in borderline hypertensives

To define the role played by various risk and behavioral factors in the increase of carotid intima-media thickness (IMT) observed in borderline hypertensives. Using B-mode ultrasonography, we compared 97 borderline hypertensives enrolled in the HARVEST study to 27 normotensive controls. Intima-media thickness was measured in the right and left common carotid artery, bulb, and internal carotid artery. Mean IMT (m-IMT), maximum IMT (M-IMT), the mean of M-IMT (M-MAX), and the prevalence of raised lesions (IMT>1 mm) were established. Compared to the controls, higher systolic BP, diastolic BP, mean arterial blood pressure levels and body mass index (BMI) were present in the borderline hypertensives, whereas age, smoking, physical activity, serum cholesterol, and triglycerides were similar. After adjusting for age, sex, heart rate, BMI, smoking, serum cholesterol, triglycerides, and physical activity, higher values of m-IMT and M-IMT were present in most carotid segments of borderline hypertensives compared with controls. After further adjustment for systolic BP and diastolic BP, differences were no longer significant. The adjusted M-MAX was 0.59+/-0.12 in borderline hypertensives compared with 0.50+/-0.10 in controls (P<0.001). After adjustment for systolic BP and diastolic BP it was 0.58+/-0.11 in borderline hypertensives compared with 0.50+/-0.12 in controls (P<0.005). In the various carotid segments, the prevalence of raised lesions was 1. 2% in borderline hypertensives compared with 0.3% in controls (P<0. 001). In the multivariate analysis m-IMT, M-IMT, and M-MAX were related to ambulatory mean arterial pressure, systolic BP and diastolic BP, serum cholesterol and triglycerides, BMI, age, and physical activity. Higher IMT values were found in subjects who were physically active than in those who were sedentary. In borderline hypertensives, an increase in IMT takes place not only in the common carotid artery but also in the bulb and the internal carotid segment. Blood pressure levels are a main determinant of m-IMT while the interaction of BP with other risk factors such as age and plasma lipids is more relevant for advanced intima-media thickening such as M-MAX.

Ambulatory impedance cardiography: a feasibility study

A wearable, ambulatory impedance monitor (AIM) has been developed to permit impedance cardiographic measurements while patients and volunteers engage in normal daily activities. The AIM system was developed for use with a new hybrid tetrapolar spot-band electrode configuration and was designed to be comfortable and inconspicuous. The objective of the present study was to provide a preliminary evaluation of AIM comparability with the widely validated Minnesota model 304B impedance cardiograph with standard tetrapolar band electrodes. Orthostatic challenge was used to systematically alter cardiac function in a laboratory setting in 11 healthy men and women. Both while the subjects were sitting and while they were standing, the AIM yielded measures of cardiac function, including heart rate, preejection period, left ventricular ejection time, and stroke volume, that were similar to those acquired by using the reference Minnesota 304B system (all Pearson R correlations > +0.87, all P < 0. 001). Cardiac responses to postural shift, expressed as change measures from sitting to standing, were also comparable for the AIM and Minnesota reference monitoring systems. Potential applications, including the assessment of 24-h hemodynamic profiles, are illustrated and discussed.

Ambulatory blood pressure monitoring for hypertension in general practice

Ambulatory blood pressure monitoring (ABPM) is being increasingly used in general practice. There is at present little published evidence regarding the clinical utility of ABPM in the care of patients with established hypertension in this setting. We examined this issue by undertaking ABPM in a group of patients with established hypertension. 40 patients (aged 33-60 years) currently being treated for hypertension were randomly selected from a general practice list and underwent a single 24-hour ABPM study. ABPM values were compared with clinic blood pressure (CBP) values obtained on the day of monitoring together with previous readings taken by the general practitioner (GP). In the case of mean arterial pressure, 24-hour, awake and asleep ABPM values were found to underestimate CBP values by 14 mmHg (95% confidence interval 11-16 mmHg), 9 mmHg (95% C16-12 mmHg) and 24 mmHg (95% CI 21-27 mmHg), respectively. When used to classify blood pressure control, ABPM values produced equivalent results to CBP except by the criterion of BP load, for which 24-hour ABPM showed a higher rate of unsatisfactory control. 5 patients classified by CBP to have satisfactory BP control according to current international guidelines were found to have unsatisfactory BP control by ABPM. This study demonstrates the potential value of ABPM in patients with essential hypertension in a general practice setting. ABPM provided information over and above that obtained by CBP in a substantial proportion of patients.