Nighttime blood pressure dipping in postmenopausal women with coronary heart disease.

BACKGROUND: Blunted nighttime blood pressure (BP) dipping is prognostic of cardiovascular morbidity and mortality. This relationship may be stronger among women than men. The present study hypothesized that coronary artery disease (CAD) and advancing age would be associated with reduced BP dipping in postmenopausal women. The effects of daytime physical activity and nighttime sleep quality on BP dipping were also examined. METHODS: 54 postmenopausal women with CAD (≥50% occlusion of at least one major coronary vessel) and 48 age-matched (range 50-80 years) postmenopausal women without CAD (non-CAD) underwent 24-h ambulatory BP monitoring and actigraphic evaluations of daytime physical activity and nighttime sleep efficiency. RESULTS: Women with CAD evidenced higher nighttime systolic BP (SBP) (P = 0.05) and blunted SBP dipping (P = 0.017), blunted diastolic BP (DBP) dipping (P = 0.047), and blunted pulse pressure dipping (P = 0.01), compared to non-CAD women. Multivariable regression models showed that the presence of CAD, age, daytime physical activity, and nighttime sleep efficiency were independently related to the magnitude of SBP dipping, together accounting for 25% of its variability. DBP dipping showed similar associations. CONCLUSIONS: For postmenopausal women, the presence of CAD and advancing age are accompanied by blunted nighttime BP dipping, which may increase the risk of adverse cardiovascular events. Lifestyle changes that increase daytime physical activity and improve nighttime sleep quality may help improve cardiovascular risk by enhancing nighttime BP dipping.

Improvements in heart rate variability with exercise therapy.

Heart rate variability (HRV) is a noninvasive, practical and reproducible measure of autonomic nervous system function. A heart rate that is variable and responsive to demands is believed to bestow a survival advantage, whereas reduced HRV may be associated with poorer cardiovascular health and outcomes. In recent years, many researchers have investigated the prognostic implications of HRV in a variety of clinical populations. Evidence suggests that reduced HRV has prognostic significance for individuals with myocardial infarction, chronic heart failure, unstable angina and diabetes mellitus. Interventions to increase HRV, such as exercise therapy, have also been examined. The findings of the present review suggest that exercise therapy may improve HRV in myocardial infarction, chronic heart failure and revascularization patients by increasing vagal tone and decreasing sympathetic activity. One hypothesis is that a shift toward greater vagal modulation may positively affect the prognosis of these individuals. While the underlying mechanisms by which exercise training improves vagal modulation are speculative at present, angiotensin II and nitric oxide may be potential mediators.

Stress, menopausal status and nocturnal blood pressure dipping patterns among hypertensive women.

BACKGROUND: A less than 10% decline in blood pressure during the night is known as a nondipping blood pressure (BP) pattern. Nondipping BP has been shown to be associated with target organ damage and poorer cardiovascular outcomes. Additionally, some evidence suggests that hyper-tensive nondipping women are at greater risk for target organ damage than hypertensive nondipping men. OBJECTIVE: To determine whether stress, demographics, menopausal status or sleep quality are associated with nondipping BP among hyperten-sive women. METHODS: A cross-sectional study design was used to describe the rela-tionship between stress and dipping status among a sample of hypertensive women and to describe the sample by age, ethnicity, marital status, meno-pausal status, current medications and sleep quality. RESULTS: The study sample consisted of 47 women (mean [+/- SD] age 57+/-13.9 years) with essential or office hypertension who underwent 24 h ambulatory BP monitoring, and completed stress and sleep quality measurements. Thirty-one women (66%) were classified as dippers and 16 (34%) were classified as nondippers. Nondippers were older (P=0.04), postmenopausal (P=0.003) and had lower stress scores (P=0.02) than their dipper counterparts. Postmenopausal status sig-nificantly predicted nondipping (OR 16; 95% CI 1.9 to 136.4). CONCLUSION: These findings were of interest given that some women had a nondipping BP pattern and significantly lower stress scores. It is pos-sible that there are fundamentally different physiological mechanisms that explain this nondipping phenomenon. In the future, the identification of specific hemodynamic mechanisms associated with nondipping could potentially influence the choice of antihypertensive treatment regimens for nondipper hypertensive patients.

The influence of coronary artery bypass graft harvest site on women's pain, functional status, and health services utilization throughout the first post-operative year: a longitudinal study.

BACKGROUND: Coronary artery bypass graft surgery is a commonly performed procedure aimed at managing coronary symptoms and prolonging life. Researchers have typically examined morbidity and mortality outcomes of predominantly male populations. Less is known about the influence of graft harvest site on recovery outcomes such as surgery-related pain, functional status, and health services utilization, especially in women. OBJECTIVES: We aimed to examine the relationships between coronary artery bypass graft harvest site (saphenous vein, internal mammary arteries or both) and surgery-related pain, functional status, health services use at 6 weeks, 12 weeks and 12 months post-operatively. DESIGN: Longitudinal extension survey following participation in a clinical trial. SETTING: Ten Canadian centres. PARTICIPANTS: Women (222) who participated in the Women's Recovery from Sternotomy Trial, underwent coronary artery bypass graft surgery with or without heart valve surgery, and completed the 12-month follow-up interview. METHODS: Harvest site data were collected by health record audit at the time of hospital discharge. Surgery-related pain, functional status, pain medication use and health services use data were collected by standardized interview over the telephone at 6 weeks, 12 weeks and 12 months post-operatively. Surgery-related pain and functional status were measured using the short Health Assessment Questionnaire. Health services use was measured by questionnaire and recorded as reported by the participants. RESULTS: Surgery-related pain, functional disability and health services use decreased over the first post-operative year. Participants who had left internal mammary artery grafts were more likely to have surgery-related pain (Adjusted Odds Ratio (AOR)=2.79; 95% Confidence Interval (CI) 1.40-5.70) and use pain medication (AOR=4.32; 95% CI 1.44-12.91) than those who had saphenous vein grafts. Conversely, participants who had saphenous vein grafts reported significantly more functional disability (AOR=2.63; 95% CI 1.16-6.25) over 12 months post-surgery than those with left internal mammary artery grafts. Participants who had pain over the course of follow-up were more likely to visit their family physician or nurse practitioner (p=0.017), visit another type of provider (i.e., naturopath or chiropractor, p=0.004), or use any health care service (p<0.0001). CONCLUSIONS: Following coronary artery bypass graft surgery, women who had left internal mammary artery grafts reported more pain and health services use while those who had saphenous vein grafts were more functionally disabled. Women who reported surgery-related pain also used more health services.

Hemodynamic response to postural shift in women with multiple chemical sensitivities.

Multiple chemical sensitivity (MCS) is a chronic condition prevalent in women; the symptoms are reproducible with repeated low-level chemical exposure. Evidence gathered through clinical observations suggests that women with MCS may be at risk for autonomic nervous system dysfunction as evidenced by abnormal heart rate and pulse pressure responses to exercise. The primary objective of this study was to describe the hemodynamic response to postural shift in 17 women with MCS. Using impedance cardiography, hemodynamic measures were taken while sitting and immediately upon standing. The hemodynamic response to standing was increased heart rate (p < .0001), decreased stroke volume (p = .002), decreased left ventricular ejection time (p < .0001), increased diastolic blood pressure (p = .01), and increased systemic vascular resistance (p =.002). Although this pattern of hemodynamic response was normal, the magnitude of the changes was considerably less than those observed previously in healthy participants. These findings warrant further investigation.

Ambulatory impedance cardiography in hypertension: a validation study.

The management of hypertension is improved by knowledge of the hemodynamics underlying blood pressure. Impedance Cardiography (ICG) provides data on a range of hemodynamic variables that affect blood pressure. However, ICG captures only fixed descriptions of hemodynamic characteristics. Improvements in ambulatory technology have led to the development of the Ambulatory Impedance Monitor (AIM) which records hemodynamic data during the activities of daily living. The purpose of this study was to evaluate the sensitivity of the AIM to detect hemodynamic changes associated with postural shift in persons with hypertension. Using a repeated measures cross-over design, sitting and standing hemodynamic measures were taken in seventeen persons with hypertension while wearing the AIM-BpTRU system designed for standard office use and the AIM-Spacelabs system designed for ambulatory monitoring. Both AIM-blood pressure monitoring systems detected significant changes from sitting to standing posture in heart rate (p=0.03), stroke volume (p=0.002), left ventricular ejection time (p<0.001), systemic vascular resistance (p=0.03) and diastolic blood pressure (p<0.001). Additionally, both systems generated measures of cardiac function that were positively correlated (p<0.001) and not significantly different (p>0.05). Our findings support previous work and demonstrate that the AIM provides valid and reliable estimates of cardiac function in persons with hypertension.

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.