The relationship between 24-hour ambulatory blood pressures and laboratory measures of cardiovascular reactivity

Social support and the reactivity hypothesis: conceptual issues in examining the efficacy of received support during acute psychological stress

Social support has been reliably related to better physical health outcomes. One influential model suggests that social support is related to lower cardiovascular disease mortality because it reduces the potentially deleterious consequences of cardiovascular reactivity during acute stress. However, received support and perceived support are separable constructs and epidemiological research suggests variability in links between received support and health. This is important because most social support and acute laboratory stress studies are essentially based on the receipt of support. In this paper, we focus on the conceptualization of received support and its implications for understanding links to support laboratory reactivity paradigms. This analysis highlights the role of theoretically important task, recipient, and provider categories of factors that moderate the effectiveness of received support, as well as the need to examine links between naturalistic perceptions of support and cardiovascular reactivity during stress.

Laboratory-based blood pressure recovery is a predictor of ambulatory blood pressure

The recovery phase of the stress response is an individual difference characteristic that may predict cardiovascular risk. The purpose of this study was to examine whether laboratory-based blood pressure (BP) recovery predicts ambulatory BP (ABP). One hundred and eighty-two participants underwent a standard laboratory stress protocol, involving a 20-min baseline rest period, and four stressors presented in a counterbalanced order, each followed by a 10-min recovery period. Participants also wore an ABP monitor for 24h during a typical workday. Hierarchical regression analyses showed that BP recovery accounted for significant additional variance for daytime SBP (p<0.001), nighttime SBP (p<0.001), daytime DBP (p<0.001), and nighttime DBP (p<0.001), after controlling for baseline and reactivity BP. Results suggest that persistence of the BP response following stress may be a more salient characteristic of the stress response in understanding its potential impact on longer term cardiovascular regulation.

Hemodynamic profile, compensation deficit, and ambulatory blood pressure

This study hypothesized that physiologically grounded patterns of hemodynamic profile and compensation deficit would be superior to traditional blood pressure reactivity in the prediction of daily-life blood pressure. Impedance cardiography-derived measures and beat-to-beat blood pressure were monitored continuously in 45 subjects during baseline and four tasks. Ambulatory blood pressure measures were obtained combining data from one work day and one off day. The mediating effects of gender and family history of hypertension were considered. Only gender was significantly associated with hemodynamic profile. Regression analysis indicated that typical reactivity measures failed to predict everyday life blood pressure. After controlling for gender and baseline blood pressure, hemodynamic patterns during specific tasks proved to be strong predictors, overcoming limitations of previous reactivity models in predicting real-life blood pressure.

Correspondence between laboratory and ambulatory measures of cardiovascular reactivity: A multilevel modeling approach

We examined the correspondence between laboratory measures of cardiovascular reactivity (CVR) and within-person changes in cardiovascular activity during the challenges of daily life, after adjustment for posture, activity, and other effects. Healthy adults (n = 335) were administered laboratory measures of CVR along with 6 days of ambulatory blood pressure monitoring and electronic diary reports. Compared with low reactors, high laboratory systolic blood pressure (SBP) reactors showed larger increases in SBP during periods of high task demand or low decisional control in daily life. High diastolic blood pressure (DBP) reactors showed larger increases in ambulatory DBP during situations rated as both low control and high demand. This multilevel modeling approach may enhance our ability to detect the correspondence between laboratory and ambulatory measures of CVR, and to identify the circumstances under which it may be most clearly observed.

Reactivity as a predictor of subsequent blood pressure: racial differences in the Coronary Artery Risk Development in Young Adults (CARDIA) Study

This study investigated the association between cardiovascular reactivity and subsequent ambulatory blood pressure in 316 black and white men and women in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Cardiovascular laboratory reactivity was examined in subjects 20 to 33 years old, and ambulatory blood pressure and heart rate were measured 3 years later. Average ambulatory pressure during a 24-hour period was regressed separately on stress reactivity and standard covariate risk factors in each race/gender subgroup. Blacks had higher blood pressure and heart rates than whites, men had higher blood pressure than women, and women had higher heart rates than men. After controlling for age, baseline systolic pressure, familial history of hypertension, smoking, alcohol consumption, body mass index, and exercise, systolic blood pressure reactivity to star tracing and cold pressor stress were significantly associated with systolic ambulatory pressure in black men and women 3 years later (partial r=0.24 to 0.37). Heart rate reactivity to video challenge and star tracing were also significantly predictive of subsequent ambulatory heart rate in blacks. Diastolic star tracing reactivity was significantly associated with subsequent ambulatory blood pressure in black women (r=0.23), and diastolic reactivity to video and star tracing were significantly predictive of ambulatory diastolic pressure in white men (r=0.39). We conclude that hyperresponsivity to stress may be a risk factor for subsequent blood pressure elevation in blacks and may be one pathway leading to the higher prevalence of hypertension in blacks than in whites.

Predictors of future ambulatory blood pressure in youth

OBJECTIVE

The objective of this study was to determine the predictors of future ambulatory blood pressure in normotensive youths with family histories of essential hypertension.

STUDY DESIGN

Eighty-eight healthy youths (mean age 10.9 +/- 2.5 years; 52 blacks, 36 whites; 45 boys) were studied. During an initial visit anthropometric variables and hemodynamics were measured at rest and before, during, and after three laboratory stressors: postural change, forehead cold, and video game challenge. The subjects' ambulatory blood pressure was monitored for 24 hours as part of a follow-up evaluation an average of 2.5 years later.

RESULTS

Anthropometric and demographic variables and measures of reactivity to laboratory stressors were related to future daytime and nighttime ambulatory blood pressure.

CONCLUSION

These findings provide important information on the predictors of ambulatory blood pressure and underscore the importance of resting blood pressure and adiposity. These results support the guidelines of the Second Task Force, which recommend the measurement of blood pressure and adiposity in the context of ongoing health care.

Test-retest reliability of 24-hour ambulatory blood pressures

The test-retest reliability of 24-hour ambulatory blood pressures (ABP) was examined using correlational analyses as well as idiographic and nomothetic time-series regression analyses. Thirty normotensives (equal males and females) underwent ABP monitoring on three occasions, each of which was separated by a week. When analyzing the data, various postural positions, activities, and locations were controlled for in order to differentially assess the effects of these variables independently. Correlational analyses found the overall test-retest reliability of the ABPs to be quite good (SBP r = .84-.88, DBP r = .83-.86, HR r = .91-.95). Correlations examined within specific postural positions, activities, and locations were also significant. The time-series regression analyses used confirmed the reproducibility of the ABPs, with no greater than 20% of the subjects showing significant changes in ABPs over the three monitoring periods. Gender effects were also examined. In general, males had significantly higher systolic ABPs overall, although there was no influence of gender in terms of the test-retest reliability of the ABPs.