Heart rate variability from short electrocardiographic recordings predicts mortality from all causes in middle-aged and elderly men. The Zutphen Study

Depressive symptoms and heart rate variability: evidence for a shared genetic substrate in a study of twins

OBJECTIVE

To clarify the relationship between depression and heart rate variability (HRV) in a sample of twins. Reduced HRV, a measure of autonomic dysfunction, has been linked to depression but many studies have inadequately controlled for familial and environmental factors. Furthermore, little is known about whether depression and HRV share common genetic pathways.

METHODS

We performed power spectral analysis on 24-hour ambulatory electrocardiograms in 288 middle-aged male twins. Log-normalized ultra low, very low, low, high frequency, and total power were calculated. A lifetime history of major depressive disorder (MDD) was determined, using the Structured Clinical Interview for Psychiatry Disorders, and current depressive symptoms were measured with the Beck Depression Inventory. Mixed-effect regression models were used to account for intrapair variability and estimate within-pair effects at the same time controlling for potential confounders.

RESULTS

Both current depressive symptoms and a history of MDD were significantly associated with lower HRV. There was a graded effect, and power in each frequency band was 29% to 36% lower in the lowest band compared with the highest BDI category. All HRV measures except high frequency remained significantly associated with current depressive symptoms in multivariable analysis, but not with lifetime history of MDD. When analyses were stratified by zygosity, a significant within-pair association between BDI score and HRV was found in the dizygotic but not in the monozygotic twins, suggesting a genetic influence on the association.

CONCLUSIONS

A shared, genetically influenced biological pathway underlies the association between depression and lower HRV. These two phenotypes may be the expression of a generalized neurobiological perturbation.

Short-term secondhand smoke exposure decreases heart rate variability and increases arrhythmia susceptibility in mice

Exposure to secondhand smoke (SHS), a major indoor air pollutant, is linked to increased cardiovascular morbidity and mortality, including cardiac arrhythmias. However, the mechanisms underlying the epidemiological findings are not well understood. Impaired cardiac autonomic function, indexed by reduced heart rate variability (HRV), may represent an underlying cause. The present study takes advantage of well-defined short-term SHS exposure (3 days, 6 h/day) on HRV and the susceptibility to arrhythmia in mice. With the use of electrocardiograph telemetry recordings in conscious mice, HRV parameters in the time domain were measured during the night after each day of exposure and 24 h after 3 days of exposure to either SHS or filtered air. The susceptibility to arrhythmia was determined after 3 days of exposure. Exposure to a low concentration of SHS [total suspended particle (TSP), 2.4 +/- 3.2; and nicotine, 0.3 +/- 0.1 mg/m(3)] had no significant effect on HRV parameters. In contrast, the exposure to a higher but still environmentally relevant concentration of SHS (TSP, 30 +/- 1; and nicotine, 5 +/- 1 mg/m(3)) significantly reduced HRV starting after the first day of exposure and continuing 24 h after the last day of exposure. Moreover, the exposed mice showed a significant increase in ventricular arrhythmia susceptibility and atrioventricular block. The data suggest that SHS exposure decreased HRV beyond the exposure period and was associated with an increase in arrhythmia susceptibility. The data provide insights into possible mechanisms underlying documented increases in cardiovascular morbidity and mortality in humans exposed to SHS.

Traffic-related particles are associated with elevated homocysteine: the VA normative aging study

RATIONALE

Recent epidemiologic studies have shown that homocysteine, a sulfur-containing amino acid formed during the metabolism of methionine, is a risk factor for atherosclerosis, myocardial infarction, stroke, and thrombosis. Particulate air pollution has been related to cardiovascular death and hospital admission, but the underlying mechanisms are not fully elucidated.

OBJECTIVES

We examined the associations between ambient particulate air pollution and plasma concentrations of homocysteine among 960 community-residing older men (mean age, 73.6 +/- 6.9 yr).

METHODS

Total homocysteine in plasma, measured using high-performance liquid chromatography with fluorescence detection, was regressed on each ambient particulate pollutant (black carbon, organic carbon, sulfate or PM(2.5)), and effect modification by plasma and dietary B vitamins (folate, B6, and B12) was examined.

MEASUREMENTS AND MAIN RESULTS

The median concentration of total homocysteine was 10.6 micromol/L. Statistically significant positive associations of total homocysteine were observed with traffic-related particles (black carbon and organic carbon). No association was observed with sulfate, an indicator of coal combustion particles, or PM(2.5) (particulate matter < or = 2.5 microm in aerodynamic diameter). The effects of black carbon and organic carbon were more pronounced in persons with low concentrations of plasma folate and vitamin B12.

CONCLUSIONS

Exposures to ambient particles, particularly from traffic, are associated with elevated plasma total homocysteine. Homocysteine may be a component or biological marker of the oxidation pathways underlying the effect of ambient particles on the cardiovascular system.

Pattern of 24-hour ambulatory blood pressure monitoring in type 2 diabetic patients with cardiovascular dysautonomy

The pathophysiological mechanisms linking cardiovascular dysautonomy to mortality are unclear. The aim of this study was to investigate the pattern of 24-h ambulatory blood pressure (BP) monitoring (ABPM) in diabetic patients with cardiovascular autonomic neuropathy (CAN). We evaluated 391 type 2 diabetic patients in a cross-sectional study. Five clinical tests of CAN were performed: heart-rate variation during deep breathing, the Valsalva maneuver, and standing, and BP variation during handgrip and standing. Patients were considered to have initial CAN if one heart-rate test was abnormal or two were borderline, and to have definite or severe CAN if at least two tests were abnormal. Differences between patients with and without CAN were assessed by bivariate tests and ANCOVA. Of the 391 patients, 230 (59%) presented clinical CAN, of whom 53 had definite or severe involvement. Patients with CAN were older, had diabetes of longer duration, and had an equal prevalence of hypertension but used more antihypertensive drugs than those without CAN. On ABPM, patients with definite or severe CAN had higher systolic BP (SBP) and pulse pressures (PP) than those without CAN, particularly in the nighttime (SBP: 128 +/- 18 vs. 117 +/- 16 mmHg, p = 0.007; PP: 58 +/- 13 vs. 50 +/- 11 mmHg, p = 0.003) and early morning (SBP: 140 +/- 18 vs. 131 +/- 17 mmHg, p = 0.05) after adjustment for potential confounders, as well as a higher prevalence of the systolic nondipping pattern (75.5% vs. 50.9%, p = 0.021). In conclusion, type 2 diabetic patients with more severe CAN have higher SBP and PP, especially during the nighttime and early morning, as well as a higher prevalence of nondipping status. This unfavorable 24-h ABPM pattern may contribute to the increased cardiovascular risk of diabetic patients with dysautonomy.

Spirituality and autonomic cardiac control

BACKGROUND

Spirituality has been suggested to be associated with positive health, but potential biological mediators have not been well characterized.

PURPOSE AND METHODS

The present study examined, in a population-based sample of middle-aged and older adults, the potential relationship between spirituality and patterns of cardiac autonomic control, which may have health significance. Measures of parasympathetic (high-frequency heart rate variability) and sympathetic (pre-ejection period) cardiac control were obtained from a representative sample of 229 participants. Participants completed questionnaires to assess spirituality (closeness to and satisfactory relationship with God). Personality, demographic, anthropometric, health behavior, and health status information was also obtained. A series of hierarchical regression models was used to examine the relations between spirituality, the autonomic measures, and two derived indexes--cardiac autonomic balance (CAB, reflecting parasympathetic to sympathetic balance) and cardiac autonomic regulation (CAR, reflecting total autonomic control).

RESULTS

Spirituality, net of demographics, or other variables were found to be associated with enhanced parasympathetic as well as sympathetic cardiac control (yielding a higher CAR) but was not associated with CAB. Although the number of cases was small (N = 11), both spirituality and CAR were significant negative predictors of the prior occurrence of a myocardial infarction.

CONCLUSIONS

In a population-based sample, spirituality appears to be associated with a specific pattern of CAR, characterized by a high level of cardiac autonomic control, irrespective of the relative contribution of the two autonomic branches. This pattern of autonomic control may have health significance.

Cardiac autonomic control and the effects of age, race, and sex: the CARDIA study

BACKGROUND

Stratification variables of age, race, and sex figure prominently in the assessment of cardiovascular disease risk. Similarly, cardiac autonomic regulation, measured by RR interval variability (RRV), is associated with risk. The relationship among these variables is unclear.

METHODS

We examined the cross-sectional relationship between RRV and age, race, and sex in 757 subjects from the NHLBI-funded Coronary Artery Disease in Young Adults (CARDIA) Study.

RESULTS

Age was a significant determinant of RRV, despite the narrow range (33-47): participants aged 33-39 years had had greater levels of HF power, LF power, and standard deviation (SD) of RR intervals than did those aged 40-47 years. There was no age effect for the LF/HF ratio. Compared to whites, blacks had lower levels of LF power, SD, and lower LF/HF. Blacks and whites did not differ in HF power. Finally, compared to men, women had lower levels of LF power, SD, and LF/HF but did not differ in HF power.

CONCLUSIONS

Data from the CARDIA study suggest that in adults in the 33-47 year age range, indices of RRV were greater in younger compared to older subjects, in men compared to women and in whites compared to blacks. These findings are broadly consistent with those of other large studies examining relationships between RRV and age, sex, and race. However, patterns of associations between RRV and these stratification variables are not entirely consistent with an underlying autonomic physiology linked to cardioprotection.

Prediction of mortality using measures of cardiac autonomic dysfunction in the diabetic and nondiabetic population: the MONICA/KORA Augsburg Cohort Study

OBJECTIVES

To evaluate whether reduced heart rate variability (HRV), prolonged corrected QT (QTc) interval, or increased QT dispersion (QTD) are predictors of mortality in the general diabetic and nondiabetic population.

RESEARCH DESIGN AND METHODS

Nondiabetic (n = 1,560) and diabetic (n = 160) subjects aged 55-74 years were assessed to determine whether reduced HRV, prolonged QTc interval, and increased QTD may predict all-cause mortality. Lowest quartiles for the maximum-minimum R-R interval difference (max-min, as measured at baseline from a 20-s standard 12-lead resting electrocardiogram without controlling for depth and rate of respiration), QTc >440 ms and QTD >60 ms, were used as cutpoints.

RESULTS

During a 9-year follow-up, 10.5% of the nondiabetic and 30.6% of the diabetic population deceased. In the nondiabetic individuals, multivariate Cox proportional hazard models adjusted for cardiovascular risk factors and demographic variables showed that prolonged QTc interval (hazard ratio 2.02 [95% CI 1.29-3.17]; P = 0.002) but not low max-min (0.93 [0.65-1.34]; P = 0.700), and increased QTD (0.98 [0.60-1.60]; P = 0.939) were associated with increased mortality. In the diabetic subjects, prolonged QTc was also a predictor of mortality (3.00 [1.34-6.71]; P = 0.007), while a trend for an increased risk was noted in those with low max-min (1.74 [0.95-3.18]; P = 0.075), whereas increased QTD did not predict mortality (0.42 [0.06-3.16]; P = 0.402).

CONCLUSIONS

Prolonged QTc interval, but not increased QTD, is an independent predictor of a twofold and threefold increased risk of mortality in the nondiabetic and diabetic elderly general population, respectively. Low HRV during spontaneous breathing tends to be associated with excess mortality in the diabetic but not nondiabetic population.

Air pollution and heart rate variability: effect modification by chronic lead exposure

BACKGROUND

Outdoor air pollution and lead exposure can disturb cardiac autonomic function, but the effects of both these exposures together have not been studied.

METHODS

We examined whether higher cumulative lead exposures, as measured by bone lead, modified cross-sectional associations between air pollution and heart rate variability among 384 elderly men from the Normative Aging Study. We used linear regression, controlling for clinical, demographic, and environmental covariates.

RESULTS

We found graded, significant reductions in both high-frequency and low-frequency powers of heart rate variability in relation to ozone and sulfate across the quartiles of tibia lead. Interquartile range increases in ozone and sulfate were associated respectively, with 38% decrease (95% confidence interval = -54.6% to -14.9%) and 22% decrease (-40.4% to 1.6%) in high frequency, and 38% decrease (-51.9% to -20.4%) and 12% decrease (-28.6% to 9.3%) in low frequency, in the highest quartile of tibia lead after controlling for potential confounders. We observed similar but weaker effect modification by tibia lead adjusted for education and cumulative traffic (residuals of the regression of tibia lead on education and cumulative traffic). Patella lead modified only the ozone effect on heart rate variability.

CONCLUSIONS

People with long-term exposure to higher levels of lead may be more sensitive to cardiac autonomic dysfunction on high air pollution days. Efforts to understand how environmental exposures affect the health of an aging population should consider both current levels of pollution and history of lead exposure as susceptibility factors.

Cardiac autonomic balance versus cardiac regulatory capacity

The concept of autonomic balance views autonomic states along a bipolar continuum from sympathetic (S) to parasympathetic (P) dominance, whereas regulatory capacity models emphasize overall autonomic flexibility as a marker of the capacity for regulation. These two concepts were evaluated for their utility in characterizing patterns of autonomic control. Measures of P (high frequency heart rate variability, HF) and S (preejection period, PEP) cardiac control were obtained. A measure of cardiac autonomic balance (CAB) was derived as the difference in the normalized P index minus the S index, and a measure of cardiac autonomic regulation (CAR) was derived as the normalized P index plus the S index. Results reveal that CAR, but not CAB, was a significant predictor of the prior occurrence of a myocardial infarction, net of demographic and other variables, whereas CAB, but not CAR, was a significant predictor of concurrent diabetes.

Autonomic nervous system activity and decline as prognostic indicators of cardiovascular and cerebrovascular events: the 'PROOF' Study. Study design and population sample. Associations with sleep-related breathing disorders: the 'SYNAPSE' Study

BACKGROUND

Transversal studies have underlined the association between the decline in autonomic nervous system (ANS) activity and all-cause mortality. However, the predictive value of ANS has never been prospectively assessed in a general population-based cohort.

METHOD

The PROOF (PROgnostic indicator OF cardiovascular and cerebrovascular events) cohort study was designed to prospectively assess the predictive value of ANS activity level in the general population, with regard to cardiovascular and cerebrovascular events, and death. This predictive power will be compared with the usual and newly discovered risk factors for the purposes of developing a risk model.

RESULTS

A prospective cohort of elderly subjects aged 65 years upon study entry were recruited from the electoral list of the city of Saint-Etienne, France. Three initial 2-year examination programs were scheduled for 7 years (2001-2007), followed by late events monitoring. At each examination, ANS activity was assessed along with clinical and biological cardiovascular risk factors, brain MRI, neuropsychological evaluation, physical activity profile, and sleep-related breathing disorders. The main study outcomes are stroke, myocardial infarction and death from any cause. A cohort consisting of 1,011 subjects aged 65.6 (0.8) years was constituted.

CONCLUSION

Despite other selective characteristics, the associations between ANS activity and events will be applicable to other populations.

Impact of bariatric surgery--induced weight loss on heart rate variability

Obesity is associated with an increased risk of sudden death that may be due to abnormal cardiac vagal modulation reflected by reduced heart rate variability (HRV). Few studies have been conducted analyzing the effect of bariatric surgery-induced weight loss on HRV assessed by 24-hour Holter monitoring. The aim of this study was to assess weight loss effect after bariatric surgery on HRV and ventricular size and function. Ten morbidly obese patients, 6 women and 4 men aged 24 to 47 years, underwent bariatric surgery. Seven morbidly obese patients without active obesity treatment were used as controls. Twenty-four-hour Holter monitoring and echocardiogram were obtained before and at 6 to 12 months after surgery or at follow-up in control patients. Changes in minimal, maximal, and mean heart rate along with HRV during daytime and nighttime were compared before and after surgery. Baseline characteristics in the control group did not differ significantly from the treatment group. Average weight in the treatment group was 141 +/- 31 kg (mean +/- SD) at baseline and decreased to 101 +/- 18 kg at follow-up, corresponding to a body mass index of 52.3 +/- 7.6 kg/m(2) at baseline and 37.7 +/- 5.3 kg/m(2) at follow-up. There was a decrease in minimal heart rate (48 +/- 10 vs 40 +/- 6 beats per minute, P = .021) and mean heart rate (82 +/- 7 vs 66 +/- 10 beats per minute, P < .001) during the Holter monitoring. Spectral analysis showed a significant enhancement in HRV parameters (high- and low-frequency power) because there was an increase in the standard deviation of normal to normal R-R intervals (116 +/- 25 vs 174 +/- 56 milliseconds, P < .001), the standard deviation of the mean R-R intervals calculated over a 5-minute period (104 +/- 25 vs 148 +/- 45 milliseconds, P < .001), the square root of the mean of the squared differences between adjacent normal R-R intervals (25 +/- 8 vs 50 +/- 20 milliseconds, P < .001), and the percentage of differences between adjacent normal R-R intervals exceeding 50 milliseconds (5% +/- 5% vs 22% +/- 13%, P < .001). Echocardiographic measures remained unchanged when comparing the groups. Weight loss after bariatric surgery enhances HRV and decreases mean and minimal heart rate during Holter monitoring through a better cardiac parasympathetic modulation.

Sleep stage dependent patterns of nonlinear heart rate dynamics in postmenopausal women

OBJECTIVE

To study the effects of sleep stage changes on nocturnal nonlinear heart rate variability (HRV) in postmenopausal women.

DESIGN

A prospective study.

POPULATION

Seventy-one healthy postmenopausal women.

METHODS

The women underwent two separate sleep studies four months apart. One steady state epoch per night of the awake state, stage 2 (light) non-REM sleep, stage 3-4 (deep) non-REM sleep and REM sleep were extracted. From the ECG, the fractal scaling exponents alpha(1) and alpha(2), approximate entropy (ApEn), the Poincaré plot variability coefficients SD1 and SD2, along with the low (LF) and high frequency (HF) bands of linear HRV as well as the LF/HF ratio were calculated.

RESULTS

None of the spectral measures of HRV changed significantly during the non-REM sleep compared to awake state. However, in non-REM sleep, alpha(2) (p<0.001) decreased significantly compared to the awake state, while alpha(1) and ApEn remained unchanged. SD1 was slightly increased in stage 2 sleep (p<0.05), while SD2 decreased in slow wave sleep (p<0.001). In REM sleep, alpha(2) values returned to the awake values, while ApEn and alpha(1) increased above the awake levels (p<0.01 for all variables), and SD1 decreased (p<0.01). HF spectral component decreased slightly (p<0.05 compared to stage 2 sleep) and LF/HF ratio increased during REM sleep (p<0.001). ApEn and alpha(2) had no correlations with any of the spectral measures of HRV, and alpha(1) had a modest correlation with the LF/HF ratio only during sleep.

CONCLUSIONS

We found that nonlinear indices of HRV describe specific features in HR dynamics during various sleep stages that are not detected by traditional spectral HRV indices.

Comparison of time and frequency domain measures of RSA in ambulatory recordings

The extent to which various measures of ambulatory respiratory sinus arrhythmia (RSA) capture the same information across conditions in different subjects remains unclear. In this study the root mean square of successive differences (RMSSD), peak valley RSA (pvRSA), and high frequency power (HF power) were assessed during ambulatory recording in 84 subjects, of which 64 were retested after about 3 years. We used covariance structure modeling to test the equality of the correlations among three RSA measures over two test days and three conditions (daytime sitting or walking and nighttime sleep) and in groups with low, medium, and high mean heart rate (HR), or low, medium, and high mean respiration rate (RR). Results showed that ambulatory RMSSD, pvRSA, and HF power are highly correlated and that their correlation is stable across time, ambulatory conditions, and a wide range of resting HR and RR values. RMSSD appears to be the most cost-efficient measure of RSA.

Effects of passive smoking on heart rate variability, heart rate and blood pressure: an observational study

BACKGROUND

Exposure to environmental tobacco smoke (ETS) has been shown to increase the risk for cardiovascular diseases and death, and autonomic dysfunction (specifically, reduced heart rate variability (HRV)) is a predictor of increased cardiac risk. This study tests the hypothesis that ETS exposure reduces HRV in the general population and discusses possible pathways.

METHODS

This cross-sectional study was conducted between 2001 and 2003 and is part of the SAPALDIA (Swiss Cohort Study on Air Pollution and Lung Diseases in Adults) study. The analysis included 1218 randomly selected non-smokers aged 50 and above who participated in 24-h electrocardiogram recordings. Other examinations included an interview, investigating health status (especially respiratory and cardiovascular health and health relevant behaviours and exposure to ETS) and measurements of blood pressure, body height and weight.

RESULTS

Subjects exposed to ETS at home or at work for more than 2 h/day had a difference of -15% in total power (95%CI: -26 to -3%), low frequency power (-28 to -1%), low/high frequency ratio (-26 to -3%) and -18% (-29 to -4%) in ultralow frequency power of HRV compared with subjects not exposed to ETS at home or work. We also found a 2.7% (-0.01 to 5.34%) higher heart rate during the recording in exposed subjects.

CONCLUSIONS

Exposure to ETS at home and work is associated with lower HRV and with higher heart rate in an ageing population. Our findings suggest that exposure to ETS increases cardiac risk through disturbances in the autonomic nervous system.

Mortality and Heart Rate in the Elderly: Role of Cognitive Impairment

Mortality related to heart rate (HR) increase in the elderly has not yet been well established. To ascertain the relationships among cognitive impairment (CI), mortality, and HR increase, the authors prospectively studied a random sample of elderly subjects stratified according to presence or absence of CI. Elderly subjects randomly selected in 1991 (n = 1332) were followed up for 12 years. Mortality was established in 98.1% of the subjects. When HR was stratified in quartiles (< 69, 70-75, 76-80, and > 80 bpm), mortality was linearly associated with increased HR in all (from 47.7 to 57.0; r2 = .43, p = .019) and in subjects without (from 41.7 to 51.1%; r2 = .50, p = .043) but not in those with CI (from 57.5 to 66.1; r2 = .20, p = .363). Cox regression analysis, adjusted for several variables, shows that HR doesn't predict mortality in all subjects (RR 0.69; 95% CI = 0.27-1.73) or in those with CI (RR 0.91; 95% CI = 0.81-1.02). In contrast, HR predicts mortality in subjects without CI (RR 1.10; 95% CI = 1.00-1.22). Hence, HR increase is a predictor of mortality in elderly subjects without CI. However, when considering all elderly subjects and those with CI, HR increase seems to have no effect on mortality. Thus, CI should be considered when focusing on HR increase as risk factor for mortality in the elderly.

Cardiac vagal control in depression: a critical analysis

Rapidly developing research has found abnormal cardiac vagal control (CVC) in several physical and mental health conditions. CVC findings in depression are mixed, and the degree to which CVC is compromised in depression is unclear. A meta-analysis of 13 rigorous cross-sectional studies reveals that a diagnosis of depression exerts a small-to-medium effect size on CVC, and explains only about 2% of the overall variance in CVC. More robust data may emerge from alternative approaches to the depression-CVC relationship, such as the use of CVC to predict the course of the disorder. Despite the vigor of recent work on CVC and depression, overall findings are suggestive rather than conclusive. Methodological desiderata and priorities for future research are discussed, including the need to clarify the etiological significance of CVC.

Clinical implications of neuroscience research in PTSD

The research showing how exposure to extreme stress affects brain function is making important contributions to understanding the nature of traumatic stress. This includes the notion that traumatized individuals are vulnerable to react to sensory information with subcortically initiated responses that are irrelevant, and often harmful, in the present. Reminders of traumatic experiences activate brain regions that support intense emotions, and decrease activation in the central nervous system (CNS) regions involved in (a) the integration of sensory input with motor output, (b) the modulation of physiological arousal, and (c) the capacity to communicate experience in words. Failures of attention and memory in posttraumatic stress disorder (PTSD) interfere with the capacity to engage in the present: traumatized individuals "lose their way in the world." This article discusses the implications of this research by suggesting that effective treatment needs to involve (a) learning to tolerate feelings and sensations by increasing the capacity for interoception, (b) learning to modulate arousal, and (c) learning that after confrontation with physical helplessness it is essential to engage in taking effective action.

Reliability and accuracy of heart rate variability metrics versus ECG segment duration

Despite the exponential growth in heart rate variability (HRV) research, the reproducibility and reliability of HRV metrics continues to be debated. We estimated the reliability of 11 metrics calculated from 5 min records. We also compared the accuracy of the HRV metrics calculated from ECG records spanning 10 s to 10 min as compared with the metrics calculated from 5 min records. The mean heart rate was more reproducible and could be more accurately estimated from very short segments (<1 min) than any of the other HRV metrics. HRV metrics that effectively highpass filter the R-R interval series were more reliable than the other metrics and could be more accurately estimated from very short segments. This indicates that most of the HRV is caused by drift and nonstationary effects. Metrics that are sensitive to low frequency components of HRV have poor repeatability and cannot be estimated accurately from short segments (<10 min).

Skipping breakfast: gender effects on resting heart rate measures in preadolescents

The cardiovascular response in children to morning nutrition has received little attention, and associated gender-related effects are virtually uninvestigated. This study evaluated resting heart-rate (HR) and heart-rate variability (HRV) in preadolescents after overnight fasting and again after eating a standardized breakfast or continuing to fast. HR increased slightly after eating and decreased significantly with continued fasting. These effects were present for both sexes. Relative to children who ate, those who continued fasting showed increases in HRV-particularly for inter-beat-interval and low frequency component (LF: 0.04-0.15 Hz) measures. Analyses revealed significant increases across variability measures for fasting children, but a selective LF decrease in those who were fed-an effect most prominent in females. Otherwise, males and females showed similar treatment-related changes in HRV. While within-gender comparisons showed similar results for HR, i.e., faster HR in fed compared with fasting males and females, respectively, fasting females-but not males-showed significantly greater increases in variability relative to their fed counterparts. Together, these findings suggest that extended overnight fasting initiates an increase in parasympathetic activity that attenuates the expected increase in cardiovascular output following a mid-morning meal. Observed gender differences were related to greater parasympathetic activity in males and to the apparent emphasis on parasympathetic regulation of LF variability. The implications of these findings for health concerns, the nature of responses to physiological and cognitive stressors, and how such differences may influence performance variables-particularly early in development when cardiovascular responses to these stressors may be more sensitive to nutritional factors-are discussed.

Heart rate variability in patients with systemic sarcoidosis

PURPOSE

The identification of subjects with systemic sarcoidosis at higher risk for sudden death is an unresolved issue. An influence of the autonomic activity on the genesis of ventricular arrhythmias was postulated. Heart rate variability (HRV) analysis provides a useful method to measure autonomic activity, and is a predictor of increased risk of death in various conditions. Therefore, the aim of the study was to evaluate HRV in patients with systemic sarcoidosis.

METHODS

The study included 35 patients with biopsy proven systemic sarcoidosis who were not taking antiarrhythmic medications. Thallium scintigraphy was performed to all patients with systemic sarcoidosis. The cardiac sarcoidosis was accepted in 16 patients as abnormal thallium scintigraphy and normal coronary arteriography. The time-domain analysis of HRV was expressed as the standard deviation of all normal to normal NN intervals (SDNN) detected during 24-hour Holter monitoring. Twenty-four healthy subjects represented a control group for HRV analysis.

RESULTS

There were no differences in age (44 +/- 13 years for cardiac sarcoidosis, 42 +/- 15 years for noncardiac sarcoidosis, and 40 +/- 10 years for control group; P = NS), sex (the ratio of female; 63%, 68%, and 55%, respectively; P = NS), and echocardiographic ejection fraction (63 +/- 10%, 67 +/- 8%, and 69 +/- 6%, respectively; P = NS) among study groups. The mean SDNN value of the group with cardiac sarcoidosis was significantly lower than both the group with noncardiac sarcoidosis and the control group (72 +/- 32 ms vs 110 +/- 46 ms and 152 +/- 36 ms; P < 0.05, respectively).

CONCLUSION

HRV is decreased in patients with systemic sarcoidosis compared to the control group. This decreasing is more obvious in patients with cardiac sarcoidosis.

Markers of autonomic tone on a standard ECG are predictive of mortality in old age

BACKGROUND

To investigate markers of autonomic tone on a standard electrocardiogram in relation to mortality in old age.

METHODS

A total of 599 inhabitants of Leiden, the Netherlands, were enrolled in a population-based follow-up study at their 85th birthday. Electrocardiograms (ECGs) were taken on entry and annually thereafter. ECGs were analysed automatically to determine four markers of autonomic tone, i.e. heart rate, the occurrence of ventricular extrasystoles and two time domain measures of heart rate variability. All participants were followed up for mortality.

RESULTS

Participants with a heart rate in the highest quartile had a 1.8-fold increased total mortality risk (95% confidence interval (CI) 1.0-3.4), but not an increased cardiovascular mortality risk. The occurrence of at least one ventricular extrasystole was related with a 2.3-fold increased total mortality risk (95% CI 1.3-3.9) and a 3.6-fold increased cardiovascular mortality (95% CI 1.6-8.2). In stratified analyses, the prognostic effect was confined to males. Both measures of heart rate variability were not related to mortality.

CONCLUSION

High heart rate and the occurrence of a ventricular extrasystole, both markers of sympathetic dominance, were predictive of mortality in old age. Two short-term measures of heart rate variability as measured on a standard 10-s ECG were not related to mortality, and hence may not reflect autonomic tone in old age.

Cardiovascular, anthropometric and neurocognitive features of healthy postmenopausal women: Effects of hormone replacement therapy

Randomized clinical trials have not shown long-term benefit of postmenopausal hormone replacement therapy (PHT) nor have they shown conclusively that the harmful consequences outweighs the benefits of the treatment. Rather, it is possible that an individualized hormone replacement therapy in questionably clinically healthy postmenopausal women may lead to different results than randomized trials.

DESIGN

In this cross-sectional study we evaluated anthropometric parameters, body composition, serum lipids, blood pressure, heart rate variability (HRV) and neurocognitive functions in 39 healthy postmenopausal women PHT users or not users (n=13, age 53.0+/-3.3 and n=26, age=53.3+/-5.0 SD, respectively) as well as in 27 younger controls (ages=33.3+/-7.1).

RESULTS

Demographic parameters were similar in women PHT users and not users. Postmenopausal women showed a significantly increase of body mass index (BMI) as well as of waist circumference, compared to younger controls, but in PHT users the values of fat free mass were intermediate between the ones of not treated and younger women. The study of HRV showed a reduction in low frequency (LF) component (sympathetic modulation) during the day, and a reduction in high frequency (HF) component (parasympathetic modulation), particularly in postmenopausal women without PHT. PHT users were characterized by autonomic parameters intermediate between younger controls and age-matched women without PHT.

CONCLUSIONS

The impact of PHT on the age-dependent changes of anthropometric features and body composition seems to be modest but positive. Furthermore, PHT seems to play a positive role on the autonomic modulation of cardiac function, through a shift of LF/HF ratio values towards those of young controls.

Effects of concentrated ambient particles on heart rate variability in spontaneously hypertensive rats

In the present study, the cardiovascular toxicity of PM(2.5) was determined in spontaneously hypertensive (SH) rats using the standard deviation of normal-to-normal intervals (SDNN) and root mean square of successive differences of adjacent normal-to-normal intervals (RMSSD) as outcome measurements. Four SH rats implanted with radiotelemetry transmitters were repeatedly exposed to concentrated PM(2.5) in nose-only exposure chambers. Gravimetric analysis revealed the mean post-concentrating mass concentration of particles during the 5 h of exposure was 202 mug/m(3). Using each animal as its own control and linear mixed-effects model, to adjust for circadian nature and individual differences, we found that SDNN decreased by 15% initially then gradually decreased to 60% of the initial value at the end of exposure. Our results indicate that concentrated PM(2.5) may decrease SDNN on SH rats during PM exposure. The study also showed that SDNN is more sensitive to PM induced effects than RMSSD.

Lower heart rate variability is associated with higher serum high-sensitivity C-reactive protein concentration in healthy individuals aged 46 years or more

BACKGROUND

To test the hypothesis of an association between cardiac autonomic activity evaluated by heart rate variability and systemic inflammatory markers such as C-reactive protein, we studied the correlation of the indices of heart rate variability relative to serum high-sensitivity C-reactive protein (hs-CRP) in a healthy Brazilian population.

METHODS

Four hundred twenty-one healthy individuals aged 15-82 years (mean 40.4 years), 184 men (43.7%) and 237 women (56.3%) were enrolled between July 1998 and July 2001. The relationship between the log-transformed indices of the heart rate variability and the serum concentration of hs-CRP were analyzed stratified by age tertile using the Spearman correlation coefficient and multiple linear regression.

RESULTS

The log standard deviation of all normal sinus RR intervals over 24 h (SDNN) (r = -0.801; p = 0.024) was independently correlated with log hs-CRP in the individuals with age in the oldest tertile (> or = 46 years). In addition, the body mass index (BMI) was independently correlated with hs-CRP in all of the age groups.

CONCLUSIONS

In the healthy subjects aged 46 years or more the lower heart rate variability correlated with higher concentration of hs-CRP.

QT dispersion and heart rate variability abnormalities in Alzheimer's disease and in mild cognitive impairment

OBJECTIVES

To investigate the effect of cardiovascular changes (i.e., QT interval, QT dispersion (QTD), heart rate variability (HRV), and other cardiovascular measures) in subjects with Alzheimer's disease (AD) and mild cognitive impairment (MCI).

DESIGN

Each subject underwent clinical and cognitive examination, a structural brain imaging study, echocardioDoppler, electrocardiogram (ECG), HRV analysis using 24-hour ECG monitoring, and 24-hour blood pressure monitoring.

SETTING

Community population-based sample of patients admitted to an AD center for investigation of cognitive disturbances.

PARTICIPANTS

Thirty-three subjects with AD, 39 subjects with MCI, and 29 cognitive healthy subjects (controls) matched for demographic characteristics, hypertensive condition, smoking habits, and laboratory parameters were enrolled consecutively.

MEASUREMENTS

Clinical and cognitive examination, structural brain imaging study, echocardioDoppler, ECG, HRV analysis using 24-hour ECG monitoring, and 24-hour blood pressure monitoring.

RESULTS

QTD and QT corrected dispersion mean values were significantly higher in patients with AD than in patients with MCI and controls and higher in patients with MCI than in controls. HRV time and domain parameters were lower in patients with AD than in patients with MCI and controls. No difference in other cardiovascular measures was found. QTD and HRV were found to be significantly correlated with the degree of cognitive impairment.

CONCLUSION

These findings support the presence of a peculiar neuroanatomic dysfunction in patients with AD and MCI that parallels the disease progression. These noninvasive parameters might prove to be powerful predictive tools in the worsening of cognitive function and mortality risk.

Air pollution and the heart : cardiovascular effects and mechanisms

There has been increasing awareness in recent years of the adverse cardiovascular effects of ambient air pollution. The recent publication of a statement from the Expert Panel on Population and Prevention Science of the American Heart Association has highlighted this issue. It has been appreciated for several decades that major pollution episodes, such as that associated with the London Fog of 1952, are responsible for increased numbers of deaths and most of these are due to cardiorespiratory causes. Realisation of this prompted government and environmental health initiatives to reduce emissions through establishing air quality standards. Previously, the major sources of air pollution were related to domestic coal burning and industry. However, the pattern of emissions in modern developed countries has changed, resulting in a pollution mixture of different composition to that on which early air quality standards were based. Even current 'lower' levels of air pollution have been shown consistently to be associated with adverse health effects. Over the past two decades, a wealth of epidemiological studies have considered both long- and short-term health effects of air pollution. Although the relative risk of respiratory disease in relation to air pollution exposure seems to be higher than that of cardiovascular disease, the latter are of greater absolute significance in population terms. A number of hypotheses have been proposed in order to explain the observed associations, and recent research efforts have focused on examining the mechanisms underlying the effects. It is suggested that certain subgroups of the population such as the elderly or those with pre-existing cardiorespiratory disease may be more susceptible to the effects of air pollution, and analysis of survival data from cohort studies supports this observation.

Electrocardiographic Predictors of Incident Congestive Heart Failure and All-Cause Mortality in Postmenopausal Women

Background— Information is limited about ECG predictors of the risk of incident congestive heart failure (CHF), particularly in women without overt manifestations of cardiovascular disease (CVD).

Methods and Results— We evaluated hazard ratios for incident CHF and all-cause mortality using Cox regression in 38 283 participants of the Women’s Health Initiative (WHI) during a 9-year follow-up. All risk models were adjusted for demographic and available clinical and therapeutic variables (multivariable-adjusted models). A backward selection procedure was used to identify dominant predictors among those that were significant as individual ECG predictors. Eleven ECG variables were significant predictors of incident CHF, with none of them having a significant interaction with baseline CVD status. From 6 dominant ECG predictors, wide QRS/T angle had a nearly 3-fold increased risk in multivariable-adjusted single ECG variable models. Two other repolarization variables, STV 5 depression and high TV 1 amplitude, and 2 QRS-related variables, QRS non-dipolar voltage and myocardial infarction (MI) by ECG, were all associated with &2-fold increase of incident CHF risk. Overall, 11 of the 12 ECG variables were significant predictors of all-cause mortality. Four variables had a significant interaction with CVD status requiring stratification. Three among these 4 were strong, dominant predictors in the CVD group: ECG MI, wide QRS/T angle, and low TV 5 amplitude had risk increase from >2-fold to 3-fold, with considerably lower risks in the CVD-free group.

Conclusions— Several repolarization variables in postmenopausal women are predictors of the risk of incident CHF and all-cause mortality as important as old ECG MI.

Short-term effect of transdermal estrogen on autonomic nervous modulation in postmenopausal women

OBJECTIVE

To evaluate the effect of short-term transdermal estradiol-l7b on cardiac autonomic nervous modulation in postmenopausal women.

DESIGN

Prospective study.

SETTING

A tertiary medical center.

PATIENT(S)

Twenty-one postmenopausal women.

INTERVENTION(S)

Transdermal estradiol or placebo therapy for 3 weeks in randomized, double-blinded, crossover fashion.

MAIN OUTCOME MEASURE(S)

Heart rate variability measures in both time and frequency domains, serum biochemistry, and climacteric symptoms were compared among baseline, placebo and transdermal estrogen therapies.

RESULT(S)

Plasma concentration of estradiol rose significantly from 11.0 +/- 5.2 pg/ml to 48.2 +/- 34.0 pg/ml after transdermal estrogen. The standard deviation of RR-interval increased significantly from 30.3 +/- 9.9 ms (placebo) to 31.3 +/- 7.4 ms (transdermal estrogen), and the coefficient of variation of RR-interval increased significantly as compared with the baseline session. The total power was marginally increased as compared among baseline, placebo, and transdermal estrogen sessions. The irritability symptom decreased significantly after transdermal estrogen therapy, as compared with baseline and placebo treatment.

CONCLUSION(S)

Transdermal estradiol for 3 weeks could significantly increase the global heart rate variability and reduce the irritability symptom in the postmenopausal women. Short-term transdermal estrogen for 3 weeks could improve cardiac autonomic nervous modulation and climacteric symptoms, and might have some cardioprotective effect in postmenopausal women.

Job strain and autonomic indices of cardiovascular disease risk

BACKGROUND

Despite the epidemiological evidence linking job strain to cardiovascular disease, more insight is needed into the etiologic mechanisms. This, in turn, would help to more precisely identify risk.

METHODS

We measured Job Strain using the Job Content Questionnaire, 8/day diary reports, and nationally standardized occupational code linkage, as well as autonomic regulation utilizing heart rate variability including spectral-derived components and QT interval variability in 36 healthy mid-aged males with varying strain jobs. The subjects wore Holter-monitors for 48 hr; this included a work and rest day.

RESULTS

Job strain (P = 0.02) and low decision latitude (P = 0.004) were associated with a reduction in cardiac vagal control (HFP) persisting throughout the 48 hr. Job strain was also associated with elevations in sympathetic control during working hours (P = 0.003).

CONCLUSIONS

The disturbed cardiovascular regulatory pattern associated with job strain may help explain the increased risk of cardiovascular diseases linked with occupational exposure.

Relationship between Daily Physical Activity and ANS Activity in Patients with CHF

PURPOSE

Heart rate variability (HRV) indices are powerful independent prognostic factors of cardiovascular events and all cause mortality in patients with chronic heart failure (CHF). This study evaluates the influence of lifestyle on HRV in CHF patients.

METHODS

Thirty-nine CHF patients (33 men, ischemic/dilated cardiomyopathy (18/21), 52.4 +/- 11.2 yr, NYHA I to III, LVEF 33.4 +/- 5.1%) filled out a physical activity questionnaire providing an individual complete qualitative and quantitative picture of their physical activity and daily energy expenditure (PAEE/DEE) corrected for age, weight, severity of the condition and autonomy. Frequency and time domain indices of HRV were calculated from ECG Holter recordings on a typical weekday. Nighttime indices were calculated in order to avoid the confounding factor of physical activity that might alter 24-h frequency analysis of HRV.

RESULTS

DEE was significantly different between classes I and II and classes I and III (P = 0.01 both) patients. Time spent in activities above 3 METs decreased significantly with the severity of the condition. Global and parasympathetic indices of 24-h HRV analysis were correlated to DEE and PAEE (Ptot24h = 78.80*PAEE (J x min x kg) -1061.80, R = 0.72, P < 0.0001). Multiple regression analysis revealed that PAEE was the sole independent factor on established HRV prognostic indices (P < 0.05) and especially within PAEE dimensions, only activities above 3 METs were correlated with established prognostic HRV indices (P < 0.05).

CONCLUSION

These results indicate that rather than total DEE, moderate to intensive physical activity may counteract the decline in HRV with chronic heart disease. This may be linked to longer time spent in higher intensity activities, and not to total activity time.

Autonomic effects of expressive writing in individuals with elevated blood pressure

We evaluated systolic and diastolic blood pressure, heart rate variability and skin conductance at baseline, and 1 and 4 months in 38 participants with elevated blood pressure, randomly assigned to expressive writing or control groups. There was a significant interaction such that the very low frequency wave of heart rate variability increased over time only in controls, suggesting potentially protective buffering in expressive writing. Systolic and diastolic blood pressure also decreased significantly from baseline to 1 month in expressive writing. Consistent with inhibition, Anger-In moderated effects of writing on 4-month DBP. Overall, expressive writing demonstrated short-term autonomic benefits and longer-term moderated effects.

A longitudinal study of physical activity and heart rate recovery: CARDIA, 1987-1993

PURPOSE

Autonomic nervous system function may be a mechanism by which frequent physical activity is associated with better coronary heart disease outcomes. In a diverse, population-based sample, we tested whether physical activity participation was associated with higher parasympathetic function.

METHODS

Participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study underwent symptom-limited graded exercise testing at baseline (1985-1986; N=3446) and at 7 yr follow-up (N=1627). Heart rate recovery (HRR), the difference between maximum heart rate (HR) and HR 2 min after test cessation, was used to estimate parasympathetic activity.

RESULTS

Participants who self-reported in the highest tertile of total physical activity (the sum of moderate- and heavy-intensity activities) had significantly faster HRR than participants in the lowest tertile (45.1 vs 41.8 beats.min, P<0.01), and the odds of having abnormal HRR (<or=22 beats.min) were 1.9 (95% confidence interval: 1.1, 3.4) times greater in the lowest versus the highest tertile after adjustment for age, race, gender, body mass index, smoking status, and diastolic blood pressure. Findings were consistent across strata of covariates. On average, HRR declined 2.5 beats.min over 7 yr. HRR declined the least among participants whose physical activity increased (-1.3 beats.min) or remained stable (-1.8 beats.min), compared with participants whose physical activity decreased (-3.6 beats.min; P<0.01 vs increase or stable).

CONCLUSIONS

In this diverse, population-based sample, physical activity was associated with faster HRR from an exercise treadmill test. Regular physical activity may blunt age-related declines in autonomic nervous system function.

Does Autonomic Function Link Social Position to Coronary Risk?

Background— Laboratory and clinical studies suggest that the autonomic nervous system responds to chronic behavioral and psychosocial stressors with adverse metabolic consequences and that this may explain the relation between low social position and high coronary risk. We sought to test this hypothesis in a healthy occupational cohort.

Methods and Results— This study comprised 2197 male civil servants 45 to 68 years of age in the Whitehall II study who were undergoing standardized assessments of social position (employment grade) and the psychosocial, behavioral, and metabolic risk factors for coronary disease previously found to be associated with low social position. Five-minute recordings of heart rate variability (HRV) were used to assess cardiac parasympathetic function (SD of N-N intervals and high-frequency power [0.15 to 0.40 Hz]) and the influence of sympathetic and parasympathetic function (low-frequency power [0.04 to 0.15 Hz]). Low employment grade was associated with low HRV (age-adjusted trend for each modality, P ≤0.02). Adverse behavioral factors (smoking, exercise, alcohol, and diet) and psychosocial factors (job control) showed age-adjusted associations with low HRV ( P <0.03). The age-adjusted mean low-frequency power was 319 ms 2 among those participants in the bottom tertile of job control compared with 379 ms 2 in the other participants ( P =0.004). HRV showed strong ( P <0.001) linear associations with components of the metabolic syndrome (waist circumference, systolic blood pressure, HDL cholesterol, triglycerides, and fasting and 2-hour postload glucose). The social gradient in prevalence of metabolic syndrome was explained statistically by adjustment for low-frequency power, behavioral factors, and job control.

Conclusions— Chronically impaired autonomic function may link social position to different components of coronary risk in the general population.

EMF and health

Electric and magnetic fields are ubiquitous in the modern society, and concerns have been expressed regarding possible adverse effects of these exposures. This review covers epidemiologic research on health effects of exposures to static, extremely low-frequency (ELF), and radio frequency (RF) fields. Research on ELF fields has been performed for more than two decades, and the methodology and quality of studies have improved over time. Studies have consistently shown increased risk for childhood leukemia associated with ELF magnetic fields, whereas ELF fields most likely are not a risk factor for breast cancer and cardiovascular disease. There are still inadequate data for other outcomes. More recently, focus has shifted toward RF exposures from mobile telephony. There are no persuasive data suggesting a health risk, but this research field is still immature with regard to the quantity and quality of available data. This technology is constantly changing and there is a need for continued research on this issue. Almost no epidemiologic data are available for static fields.

Dose-response relationship of endurance training for autonomic circulatory control in healthy seniors

Aging results in marked abnormalities of cardiovascular regulation. Regular exercise can improve many of these age-related abnormalities. However, it remains unclear how much exercise is optimal to achieve this improvement or whether the elderly can ever improve autonomic control by exercise training to a degree similar to that observed in healthy young individuals. Ten healthy sedentary seniors [71 +/- 3 (SD) yr] trained for 12 mo; training involved progressive increases in volume and intensity. Static hemodynamics were measured, and R-wave-R-wave interval (RRI), beat-to-beat blood pressure (BP) variability, and transfer function gain between systolic BP and RRI were calculated at baseline and every 3 mo during training. Data were compared with those obtained in 12 Masters athletes (68 +/- 3 yr) and 11 healthy sedentary young individuals (29 +/- 6 yr) at baseline. Additionally, the adaptation of these variables after completion of identical training loads was compared between the seniors and the young. Indexes of RRI variability and baroreflex gain were decreased in the sedentary seniors but preserved in the Masters athletes compared with the young at baseline. With training in the seniors, baroreflex gain and resting BP showed a peak adaptation after moderate doses of training following 3-6 mo. Indexes of RRI variability continued to improve with increasing doses of training and increased to the same magnitude as the young at baseline after heavy doses of training for 12 mo; however, baroreflex gain never achieved values equivalent to the young at baseline, even after a year of training. The magnitude of the adaptation of these variables to identical training loads was similar (no interaction effects of age x training) between the seniors and the young. Thus RRI variability in seniors improves with increasing "dose" of exercise over 1 yr of training. In contrast, more moderate doses of training for 3-6 mo may optimally improve baroreflex sensitivity, associated with a modest hypotensive effect; however, higher doses of training do not lead to greater enhancement of these changes. Seniors retain a similar degree of "trainability" as young subjects for cardiac autonomic function to dynamic exercise.

Short-Term Adjuvant Atorvastatin Improves Frequency Domain Indices of Heart Rate Variability in Stable Systolic Heart Failure

The autonomic nervous system marks beneficial drug responses in systolic heart failure management. The impact of statin therapy in this broad disease class is unclear and patient studies are extremely limited.

METHODS

We studied a group of 23 patients with stable systolic ventricular impairment and randomised them single (patient) blind to high dose Atorvastatin 40 mg daily or placebo in addition to standard therapies over a 12-week treatment interval. Impact on the autonomic nervous system was assessed by anonymised short-term (20 min) standardised supine heart rate variability analyses.

RESULTS

Two subjects withdrew one due to decompensation and one due to gastric intolerance. The remaining subjects completed both monitoring events without changes in standard medicines. Frequency domain but not time domain HRV indices improved with active statin therapy suggesting beneficial effects in attenuating sympathetic tone.

CONCLUSIONS

In this small study we saw short-term high potency statin treatment had a beneficial impact on frequency domain HRV measures suggestive of an impact on sympatho-activation. We found no effect on time domain HRV indices. This may suggest a lesser or no effect on parasympathetic tone.

Interval training in elderly men increases both heart rate variability and baroreflex activity

AIMS

Autonomic nervous system activity decreases continuously with age and appears to be a powerful predictor of disease and death. Attempts are thus made to reactivate autonomic drive with the intent of improving health.

METHODS

We assessed maximal oxygen consumption (VO2max), autonomic nervous system activity by heart rate variability (HRV) analysis and spontaneous cardiac baroreflex activity (SBR) in eleven elderly men (73.5+/-4.2 years) before and after a 14-week program of intensive cycloergometer interval training. The standard HRV indices were calculated using time domain (mean RR, PNN50, RMSSD, SDNN, SDANN and SDNNIDX), and Fourier transform (total power, ULF,VLF, LF, LFnu, HF, HFnu and LF/HF) analyses of 24-hour, daytime and nighttime Holter recordings. The SBR was calculated from 15-minute recordings of spontaneous blood pressure and RR interval variations using the sequence (slope, slSBR) and cross-spectral (alphaSBRHF and alphaSBRLF) methods.

RESULTS

After the training period,VO2max increased by 18.6 % (26.8+/-4.4 to 31.8+/-5.2 ml.kg(-1).min(-1), p<0.01). The nocturnal parasympathetic indices of HRV increased (PNN50: 3.05+/-2.21 to 5.00+/-2.87%, RMSSD: 29.1+/-7.6 to 38.8+/-10.9 ms, HF: 117+/-54 to 194+/-116 ms2/Hz, all p<0.05) as did the SBR indices (slSBR: 7.0+/-1.8 to 9.8+/-2.1 ms.mmHg(-1), p<0.01; alphaSBRHF: 6.9+/-2.2 to 10.5+/-3.7 ms.mmHg(-1), p<0.05; alphaSBRLF: 5.3+/-2.3 to 6.9+/-3.1 ms.mmHg(-1), p=0.22).

CONCLUSION

Intensive endurance training in elderly men enhanced parasympathetic parameters of HRV and, interestingly, of SBR. Physiological mechanisms and long-term clinical effects on health status should be further investigated.

Wine drinking is associated with increased heart rate variability in women with coronary heart disease

OBJECTIVE

To test the hypothesis that alcohol consumption is positively related to heart rate variability (HRV) in women with coronary heart disease (CHD) and therefore that cardiac autonomic activity is potentially implicated in the mediation of the favourable effects of moderate drinking.

DESIGN, SETTINGS, AND PATIENTS

Cross sectional study of female patients who survived hospitalisation for acute myocardial infarction or underwent a revascularisation procedure, percutaneous transluminal coronary angioplasty, or coronary artery bypass grafting.

MAIN OUTCOME MEASURES

Ambulatory 24 hour ECG was recorded during normal activities. The mean of the standard deviations of all normal to normal intervals for all five minute segments of the entire recording (SDNNI) and the following frequency domain parameters were assessed: total power, high frequency power, low frequency power, and very low frequency power. A standardised questionnaire evaluated self reported consumption of individual alcoholic beverage types: beer, wine, and spirits. Other clinical characteristics, such as age, body mass index, smoking habits, history of diabetes mellitus, menopausal status, educational status, and treatment, were also assessed.

RESULTS

Wine intake was associated with increased HRV in both time and frequency domains independently of other clinical covariates (for example, ln SDNNI was 3.89 among wine drinkers v 3.59 among wine non-drinkers in the multivariate model; p = 0.014). In contrast, consumption of beer and spirits and the total amount of alcohol consumed did not relate significantly to any of the HRV parameters.

CONCLUSION

Intake of wine, but not of spirits or beer, is positively and independently associated with HRV in women with CHD. These results may contribute to the understanding of the complex relation between alcohol consumption and CHD.

Effects of air pollution on heart rate variability: the VA normative aging study

Reduced heart rate variability (HRV), a marker of poor cardiac autonomic function, has been associated with air pollution, especially fine particulate matter [< 2.5 microm in aerodynamic diameter (PM2.5)]. We examined the relationship between HRV [standard deviation of normal-to-normal intervals (SDNN), power in high frequency (HF) and low frequency (LF), and LF:HF ratio] and ambient air pollutants in 497 men from the Normative Aging Study in greater Boston, Massachusetts, seen between November 2000 and October 2003. We examined 4-hr, 24-hr, and 48-hr moving averages of air pollution (PM2.5, particle number concentration, black carbon, ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide). Controlling for potential confounders, HF decreased 20.8% [95% confidence interval (CI), 4.6-34.2%] and LF:HF ratio increased 18.6% (95% CI, 4.1-35.2%) per SD (8 microg/m3) increase in 48-hr PM2.5. LF was reduced by 11.5% (95% CI, 0.4-21.3%) per SD (13 ppb) increment in 4-hr O3. The associations between HRV and PM2.5 and O3 were stronger in people with ischemic heart disease (IHD) and hypertension. The associations observed between SDNN and LF and PM2.5 were stronger in people with diabetes. People using calcium-channel blockers and beta-blockers had lower associations between O3 and PM2.5 with LF. No effect modification by other cardiac medications was found. Exposures to PM2.5 and O3 are associated with decreased HRV, and history of IHD, hypertension, and diabetes may confer susceptibility to autonomic dysfunction by air pollution.

Unprecedented improvements in short-term heart rate variability due to Thought Field Therapy: response to the Pignotti retraction

Short-term heart rate variability (S-HRV) is a valid and reliable measure of health and therapy effectiveness. Pignotti makes critical assertions about S-HRV with no evidence or authoritative support for these curious assertions. Short-term measures have advantages over long-term measures. The power of Thought Field Therapy (TFT) is demonstrated through unprecedented HRV improvements as well as other physiologic indices such as skin color, microscopic measures, and increases in T-cell numbers after successful TFT. Bilchick and associates' hypothesis (2002), "Each increase of 10 ms in standard deviation of normal-to-normal (SDNN) conferred a 20% decrease in risk of mortality (p = .0001)," is a bold and speculative position that appears to have general, if not highly specific, merit when applied to all groups investigated with HRV.

Inflammatory markers and heart rate variability in women with coronary heart disease

PURPOSE

Both heart rate variability (HRV) and inflammatory markers are carrying prognostic information in coronary heart disease (CHD), however, we know of no studies examining their relation in CHD. The aim of this study, therefore, was to assess the association between HRV and inflammatory activity, as reflected by the levels of interleukin-6 (IL-6), IL-1 receptor antagonist (IL-1ra) and C-reactive protein (CRP).

SUBJECTS AND METHODS

Consecutive women patients who survived hospitalization for acute myocardial infarction, and/or underwent a percutaneous transluminal coronary angioplasty or a coronary artery bypass grafting were included and evaluated in a stable condition 1 year after the index events. An ambulatory 24-h ECG was recorded during normal activities. SDNN index (mean of the standard deviations of all normal to normal intervals for all 5-min segments of the entire recording) and the following frequency domain parameters were assessed: total power, high frequency (HF) power, low frequency (LF) power and very low frequency (VLF) power. Levels of high-sensitivity CRP were measured by nephelometry, IL-6 and IL-1ra concentrations were determined by enzyme immunoassay.

RESULTS

Levels of IL-6 showed an inverse relation with HRV measures even after controlling for potential confounding factors. The P-values were 0.02, 0.04, 0.01, 0.03, 0.18 for the multivariate association with SDDN index, total power, VLF power, LF power and HF power respectively. In contrast, the inverse relationship between HRV measures and CRP or IL-1ra levels were weak and nonsignificant. Correlation coefficients for the relationship between IL-6 and HRV measures were both uni- and multivariately higher than for the relationship between HRV measures and any other factors evaluated in this study.

CONCLUSION

Concentration of IL-6 showed a negative, independent association with HRV in women with CHD. Thus, increased inflammatory activity, as reflected by IL-6 levels, may represent a new auxiliary mechanism linking decreased HRV to poor prognosis in CHD.

Heritability of ambulatory heart rate variability

BACKGROUND

Reduced heart rate variability (HRV) is a prognostic factor for cardiac disease and cardiac mortality. Understanding the sources of individual differences in HRV may increase its diagnostic use and provide new angles for preventive therapy. To date, the contribution of genetic and environmental factors to the variance in HRV has not been investigated during prolonged periods of ambulatory monitoring in a naturalistic setting.

METHODS AND RESULTS

In 772 healthy twins and singleton siblings, ambulatory ECG was recorded during 24 hours. Two time domain measures of HRV were used: the standard deviations of all normal-to-normal intervals across 5-minute segments (SDNN index) and the root mean square of successive differences between adjacent normal RR intervals (RMSSD). Multivariate genetic analyses across 4 periods of day (morning, afternoon, evening, night) yielded significant estimates for genetic contribution to the mean ambulatory SDNN index (ranging from 35% to 47%) and the mean ambulatory RMSSD (ranging from 40% to 48%).

CONCLUSIONS

Ambulatory HRV measures are highly heritable traits that can be used to support genetic association and linkage studies in their search for genetic variation influencing cardiovascular disease risk.