Changes In Heart Rate Variability Indices Research Articles

Effects of weight loss through lifestyle changes on heart rate variability in overweight and obese patients: A systematic review

The effects of calorie restriction and physical activity on autonomic regulation and cardiac vagal control in overweight and obese individuals remain inconsistent. Thus, this systematic review aimed to evaluate the weight loss effects through lifestyle changes on heart rate variability (HRV) markers in overweight and obese subjects. A systematic search for studies published up to November 2021 was conducted in MEDLINE, Embase, EBSCO host and VHL REGIONAL/LILACS. The main outcomes were changes in HRV indices from pre- and post-nutritional intervention and exercise in overweight and obese individuals. This review was registered in PROSPERO: CRD42021274467. The literature search retrieved 959 articles, of which 12 were included in this review. The intervention in nine studies was diet only, in two studies was diet and exercise, and in one study diet was compared to diet and exercise. The weight loss was greater than 10% in four studies and between 5 and 10% in three studies. Most of the studies revealed that weight loss through lifestyle changes seems to promote beneficial effects on HRV, restoring sympathovagal balance by increasing parasympathetic activity and reducing sympathetic activation. This systematic review exhibited the beneficial effects of weight loss through lifestyle changes on cardiac autonomic control in overweight and obese individuals. Future investigations need standardization of HRV indices for better interpretation of autonomic function in different clinical situations.

Cardiac autonomic disturbance following resistance and sprint-interval exercises in non-obese and obese young men.

This study examined the alterations of heart rate variability (HRV) following iso-duration resistance (RES) and sprint-interval exercises (SIE) by comparing with that of non-exercise control (CON) in 14 non-obese (NOB) and 15 obese (OB) young men. Time and frequency domain measures as well as nonlinear metrics of HRV were assessed before and immediately after exercise, and during every 20min until 120min post-exercise. The variables during the first 4h of actual sleep time at night, and the period of 12-14h post-exercise were also measured. All trials were scheduled at 20:00. It was found that RES and SIE attenuated the HRV in both NOB and OB (P<0.05), and the attenuated HRV restored progressively during subsequent recovery. Although the changes in HRV indices among various time points during the recovery period and its interaction across RES, SIE, and CON were not different between NOB and OB, the restoration of the declined HRV indices to corresponding CON level in the 2 exercise trials in OB appeared to be sluggish in relative to NOB. Notwithstanding, post-exercise HRV that recorded during actual sleep at night and during 12-14h apart from exercise were unvaried among the 3 trials in both groups (P>0.05). These findings suggest that obesity is likely to be a factor hindering the removal of exercise-induced cardiac autonomic disturbance in young men. Nonetheless, the declined HRV following both the RES and SIE protocols was well restored after a resting period of ∼10h regardless of obesity. The study was registered at ISRCTN as https://doi.org/10.1186/ISRCTN88544091.

Heart rate variability and meditation: a meta-analysis

Abstract Funding Acknowledgements Type of funding sources: None. Background Meditation can induce changes in autonomic balance, which can benefit cardiovascular health. The present meta-analysis evaluated changes in heart rate variability (HRV) in meditators. Methods PubMed and Embase were searched for primary prospective studies using the search terms ‘heart rate variability’ and ‘meditation’ until January 18th, 2019. The statistical significance of the difference between subgroups is evaluated by the standardized mean difference (SMD), 95% confidence interval (CI), and P-value. I2 value was used to assess the statistical heterogeneity between the included studies. Results Twenty-one studies involving 538 meditators (experienced= 209, beginners= 329) and 334 controls (mean age= 40.61, 35% male) were included. Regarding time-domain indices, no statistically significant differences were observed when assessing HRV between i) meditators versus controls (SMD= -0.17; 95% CI: [-0.50, 0.17]; p= 0.30; I2= 0%), ii) pre- versus post-meditation (SMD= -0.41; 95% CI: [-1.10, 0.28]; p= 0.25; I2= 80%) or iii) at baseline versus during meditation (SMD= -0.40; 95% CI: [-0.94, 0.14]; p= 0.14; I2= 72%). Pertaining to frequency-domain indices, analysis of low frequency (LF), normalized low frequency (LFnu) and high frequency (HF) between i) meditators versus controls, ii) at baseline versus post-meditation and iii) at baseline versus during meditation yet again did not show any variations. Seven studies assessed normalized high frequency (HFnu) at baseline versus during meditation collectively demonstrated a significantly higher HFnu during meditation in beginners with notable heterogeneity (SMD= 1.29; 95% CI: [0.09, 2.49]; p= 0.04; I2= 95). Moreover, LF/HF was evaluated by seven studies at baseline versus during meditation. Both meta-analysis (SMD= 0.76; 95% CI: [-0.17, 1.69]; p= 0.11; I2= 94%) as well as subset analysis of experienced meditators (SMD= -0.46; 95% CI: [-0.88, -0.03]; p= 0.03; I2= 0%) revealed a significantly lower LF/HF at baseline. Conclusions Short-term changes in HRV indices were observed during meditation, but there is limited evidence for significant long-term effects.

Longitudinal Autonomic Nervous System Measures Correlate With Stress and Ulcerative Colitis Disease Activity and Predict Flare.

Differences in autonomic nervous system function, measured by heart rate variability (HRV), have been observed between patients with inflammatory bowel disease and healthy control patients and have been associated in cross-sectional studies with systemic inflammation. High HRV has been associated with low stress. Patients with ulcerative colitis (UC) were followed for 9 months. Their HRV was measured every 4 weeks using the VitalPatch, and blood was collected at baseline and every 12 weeks assessing cortisol, adrenocorticotropin hormone, interleukin-1β, interleukin-6, tumor necrosis factor-α, and C-reactive protein (CRP). Stool was collected at enrollment and every 6 weeks for fecal calprotectin. Surveys assessing symptoms, stress, resilience, quality of life, anxiety, and depression were longitudinally collected. Longitudinally evaluated perceived stress was significantly associated with systemic inflammation (CRP, P = 0.03) and UC symptoms (P = 0.02). There was a significant association between HRV and stress (low-frequency to high-frequency power [LFHF], P = 0.04; root mean square of successive differences [RMSSD], P = 0.04). The HRV was associated with UC symptoms (LFHF, P = 0.03), CRP (high frequency, P < 0.001; low frequency, P < 0.001; RMSSD, P < 0.001), and fecal calprotectin (high frequency, P < 0.001; low frequency, P < 0.001; RMSSD, P < 0.001; LFHF, P < 0.001). Significant changes in HRV indices from baseline developed before the identification of a symptomatic or inflammatory flare (P < 0.001). Longitudinally evaluated HRV was associated with UC symptoms, inflammation, and perceived and physiological measures of stress. Significant changes in HRV were observed before the development of symptomatic or inflammatory flare.

Association between heart rate variability indices and features of spontaneous ventricular tachyarrhythmias in mice.

Direct evidence is limited for the association between heart rate variability (HRV) indices and ventricular tachyarrhythmias (VTAs). While galectin-3 (Gal-3) is regarded as a causal factor for cardiac remodelling and a biomarker for arrhythmias, its regulation on VTAs and HVR is unknown. Using aged transgenic (TG) mice with cardiac overexpression of β2 -adrenoceptors and spontaneous VTAs, we studied whether changes in HRV indices correlated with the severity of VTAs, and whether Gal-3 gene knockout (KO) in TG mice might limit VTA. Body-surface ECG was recorded (10-minute period) in 9- to 10-month-old mice of non-transgenic (nTG), TG and TG×Gal-3 knockout (TG/KO). Time-domain, frequency-domain and nonlinear-domain HRV indices were calculated using the R-R intervals extracted from ECG signals and compared with frequency of VTAs. TG and TG/KO mice developed frequent VTAs and showed significant changes in certain time-domain and nonlinear-domain HRV indices relative to nTG mice. The severity of VTAs in TG and TG/KO mice in combination, estimated by VTA counts and arrhythmia score, was significantly correlated with certain time-domain and nonlinear-domain HRV indices. In conclusion, significant changes in HRV indices were evident and correlated with the severity of spontaneous VTAs in TG mice. The frequency of VTA and HRV indices were largely comparable between TG and TG/KO mice. Deletion of Gal-3 in TG mice altered certain HRV indices implying influence by neuronally localized Gal-3 on autonomic nervous activity.

Major depressive disorder and insomnia: Exploring a hypothesis of a common neurological basis using waking and sleep-derived heart rate variability

It remains unclear whether neurobiological dysfunction observed in major depressive disorder (MDD) and insomnia is an expression of common or independent bases. The present investigation sought to explore differences in heart rate variability (HRV)—a widely utilized biomarker of neurobiological functioning—among individuals with MDD, insomnia, and healthy controls, while awake and during distinct sleep stages (REM, N2), with the goal of improving our understanding of shared neurobiological factors in depression and insomnia. Participants were 73 adults who underwent home polysomnography. All N2 and REM sleep epochs with a duration greater than or equal to 5 min were identified for HRV analysis. Additionally, a single waking epoch was defined for each participant. From waking to N2 sleep, and waking to REM sleep, changes in HRV indices indicated participants experienced reductions in sympathetic arousal and increases in parasympathetic arousal. Contrary to hypotheses, however, no between group differences were observed in HRV. Though the present findings do not support the hypotheses of a shard neurobiological pathway between MDD and insomnia, more work is warranted to advance our understanding of the neurobiological bases of these common, debilitating, and frequently co-occurring psychiatric conditions, to improve early detection and identify novel intervention targets for these disorders.

Non-contact monitoring of heart rate variability using medical radar for the evaluation of dynamic changes in autonomic nervous activity during a head-up tilt test

Electrocardiography (ECG) is a mandatory standard for monitoring electrical activity of the heart in many clinical settings such as intensive care and emergency units. However, in situations wherein the skin is damaged, such as acute burn injuries, it is impossible to efficiently attach electrodes to the skin. In this study, we developed a non-contact cardiac monitoring system using a 24-GHz medical radar for directly measuring the beat-to-beat heart mechanical activity at a distance from a subject. The heart rate variability (HRV) was analysed using an autoregressive model (AR) from the measured beat-to-beat intervals during a head-up tilt test. To investigate the feasibility of the proposed system, we compared medical radar and ECG recording by using Lin’s correlation coefficient and Bland–Altman analysis, which showed a negligible mean difference from the substantial agreement of Lin’s correlation coefficient of 0.9 between the radar and ECG. The non-contact radar clearly monitored dynamic changes in HRV indices induced by the head-up tilt test. This type of non-contact HRV-sensing technique as an alternative approach has significant potential for advancing personal healthcare in both clinical and out-of-hospital settings.

Higher levels of Depressive Symptoms are Associated with Increased Resting-State Heart Rate Variability and Blunted Reactivity to a Laboratory Stress Task among Healthy Adults.

Laboratory stress tasks induce strong changes in linear and non-linear indices of heart rate variability (HRV) among healthy adults, due to a task-induced parasympathetic withdrawal. Previous findings suggested that negative affectivity and its correlates (i.e., depressive symptoms, anxiety, hostility, type D personality, and situational stress) could profoundly affect autonomic activity. However, to date no studies considered these psychological dimensions simultaneously while trying to disentangle their acute effects on HRV during a laboratory stress task. A total of 65 healthy participants completed a battery of questionnaires and later underwent a psychosocial stress protocol, which involves a stressful and a non-stressful mental arithmetic task, with the latter serving as a control condition for the former. During the entire procedure, autonomic activity was recorded through a portable ECG device. We analysed longitudinal changes in HRV indices using Mixed Models, taking into account respiration rates and the associations between psychophysiological variables through bivariate Pearson's r (partial) correlation indices. We found significant changes in linear (e.g., HF power, RMSSD) and non-linear (e.g., Poincaré Plot and Correlation Dimension D2) HRV indices during the procedure, with the lowest point reached during the stressful mental arithmetic task. Interestingly, only depressive symptomatology was significantly and positively related to a higher resting-state HRV and to a blunted reactivity to the stress task, even after controlling for baseline values. Results suggest that healthy individuals with higher levels of depressive symptoms could experience atypical cardiovascular responses to stressful events: several speculative interpretations, considering autonomic, behavioral, and motivational dysregulations, are discussed.

Influence of Heart Rate, Age, and Gender on Heart Rate Variability in Adolescents and Young Adults.

Key autonomic functions are in continuous development during adolescence which can be assessed using the heart rate variability (HRV). However, the influence of different demographic and physiological factors on HRV indices has not been fully explored in adolescents. In this study we aimed to assess the effect of age, gender, and heart rate on HRV indices in two age groups of healthy adolescents (age ranges, 13-16 and 17-20years) and two groups of healthy young adults (21-24 and 25-30years). We addressed the issue using 5-min ECG recordings performed in the sitting position in 255 male and female participants. Time, frequency, and informational domains of HRV were calculated. Changes in HRV indices were assessed using a multiple linear regression model to adjust for the effects of heart rate, age, and gender. We found that heart rate produced more significant effects on HRV indices than age or gender. There was a progressive reduction in HRV with increasing age. Sympathetic influence increased with age and parasympathetic influence progressively decreased with age. The influence of gender was manifest only in younger adolescents and young adults. In conclusion, age, gender, and particularly heart rate have a substantial influence on HRV indices, which ought to be considered to avoid biases in the study of the autonomic nervous system development. The lack of the gender-related effects on HRV indices in late adolescence could be related to non-completely achieved maturity of the autonomic mechanisms, which deserves further exploration.

Exploring the Effect of a Maximal Exercise Test on Heart Rate Variability in Young Adults

Heart rate variability (HRV) is a commonly used tool in biobehavioral and biomedical research and may represent a non-traditional marker of disease risk. Few data exist investigating relationships between HRV and concurrent measurements of maximal exercise capacity, adiposity and heart rate recovery (HRR) in the general population. Additionally, HRV or vagal response to/and following an exercise task may independently be related to current and future health status. PURPOSE: To investigative the effects of a maximal exercise test on HRV and to explore associations between changes in HRV indices in response to exercise and fitness, adiposity and acute HRR. METHODS: As part of a larger longitudinal study, 27 young adults (Age=18-20 years, Female=48%) completed a graded maximal exercise test. HRV was assessed at two times (pre- and ~20 mins post-exercise) via an orthostatic challenge (5 min in each posture: supine, seated, standing). HRR at 2 and 4 min post-exercise was assessed as reduction in HR following exercise test cessation using the Polar RS800CX. Adiposity was measured by BodPod. HRV was processed using Kubios (v2.1, Finland). A two-way RM-ANOVA (posture*time) was used to assess the effect of maximal exercise on HRV. Spearman correlations were performed to identify associations between baseline HRV and health variables. RESULTS: Significant interactions for posture x time were seen for RMSSD (time domain) (p<0.001), approximate entropy (ApEn) (p<0.001), and baseline HR (p<0.001). Both baseline ApEn and resting HR were negatively correlated with VO2max (-0.49, p=0.009; -0.52, p=0.005, respectively) and HRR at 2 min (-0.49, p=0.009; -0.68, p<0.001, respectively). Neither baseline HRV indices nor change in HRV were related to adiposity, but changes in several HRV indices were associated with HRR and VO2max. CONCLUSION: As anticipated, maximal exercise resulted in significant posture specific changes in HRV. Continued exploration into the time-course of HRV recovery is needed, particularly as it relates to the dynamics of HRR in the initial minutes post-exercise. To interpret the potential utility of HRV measures, further investigation should focus on the relationships between HRV and traditional disease risk biomarkers in a variety of contexts. Support provided by NIMH 58144, NICHD R01 HD078346-01A1

Assessment of cardiac sympathovagal activity in overweight young adult males

Background: When a person’s body mass index (BMI) is above the normal range but below the threshold for obesity, he or she is termed as overweight (BMI = 25–29.9 kg/m2). Recently, the incidence of myocardial infarction has greatly increased among the young adults. This is mainly due to stress, sedentary lifestyle, and increased intake of junk foods. Reduced heart rate variability (HRV) is a sign of poor cardiac autonomic function. Obese individuals are known to have reduced HRV. However, there are not many studies that have explored the changes in HRV indices among the overweight individuals. Aims and Objective: To find out the influence of higher BMI on HRV in overweight young adult men. Materials and Methods: Eighteen men (30 ± 4 years, mean ± SD) with BMI in the overweight range (test group) and 18 age-matched men with normal BMI (control group) were included in the study. Five-minute ECG was recorded in lead II configuration in all the subjects following 10 min of rest in supine posture. HRV parameters (time domain and frequency domain) were derived from the ECG. The HRV parameters of the test and the control group were compared using Mann–Whitney U-test. A p-value of

Heart rate variability is reduced in sedentary young females with higher body mass index

Background: Heart rate variability (HRV) is affected by respiration, circadian factors, environmental factors, yoga, and exercises. There are emerging reports of myocardial infarction in young adults. Reduced HRV is a sign of poor autonomic function. Sedentary life habits in the younger generation have become an important issue in consideration along with the unmodifiable risk factors such as aging and hormonal influences. Several studies have shown that young obese males have reduced HRV. However, there are not many studies, which have explored the changes in HRV indices in young females with higher body mass index (BMI). Aims and Objectives: The aim of this study was to assess and compare the HRV status of young women with higher BMI and women with normal BMI. Materials and Methods: A total of 40 apparently healthy females of age between 18 and 25 years were recruited in the study. Sedentary behavior was assessed using the International Physical Activity Questionnaire. According to BMI (WHO guidelines for Asian population), subjects were divided into test group (BMI >23 kg/m2 and waist/hip [W/H] ratio >0.8, n = 20) and control group (BMI = 18-23 kg/m2, W/H ratio

HEART RATE VARIABILITY TRENDS IN PATIENTS RECEIVING A SIX-MONTH COURSE OF BEVACIZUMAB - A CARDIOTOXIC ANTI-CANCER AGENT

BackgroundBevacizumab is a humanized monoclonal antibody that inhibits the activity of vascular endothelial growth factor. It has demonstrated activity against several malignancies. Adverse cardiovascular effects that have been reported in association with bevacizumab include hypertension, endothelial dysfunction and heart failure. Animal models have suggested autonomic nervous system (ANS) toxicity as one potential mechanism for these effects. We have previously reported on the acute and short-term effects of this drug and we report on the medium-term effects herein.MethodsPatients were recruited among those beginning bevacizumab for the treatment of metastatic colon cancer. Demographics and clinical characteristics of the patients at the time of enrollment were collected. A 10-minute high-resolution ECG was recorded prior to a first dose of bevacizumab and analysed for heart rate variability (HRV), a marker of ANS dysfunction. Patients returned 6 months after their initial visit and had a repeat 10-minute ECG recording. Paired t-tests were used to compare baseline HRV recordings to those recorded after a 6-month course of the drug.ResultsTen patients without a significant cardiac history were enrolled. Seven patients survived to 6 months of follow up and are included in this analysis. Mean patient age was 64 years and 6 were male. All were in sinus rhythm and had normal systolic function by echocardiography. Changes in HRV indices are reported in Table 1.ConclusionKGH Garfield Kelly Award, KGH/HDH Cardiac Program Award BackgroundBevacizumab is a humanized monoclonal antibody that inhibits the activity of vascular endothelial growth factor. It has demonstrated activity against several malignancies. Adverse cardiovascular effects that have been reported in association with bevacizumab include hypertension, endothelial dysfunction and heart failure. Animal models have suggested autonomic nervous system (ANS) toxicity as one potential mechanism for these effects. We have previously reported on the acute and short-term effects of this drug and we report on the medium-term effects herein. Bevacizumab is a humanized monoclonal antibody that inhibits the activity of vascular endothelial growth factor. It has demonstrated activity against several malignancies. Adverse cardiovascular effects that have been reported in association with bevacizumab include hypertension, endothelial dysfunction and heart failure. Animal models have suggested autonomic nervous system (ANS) toxicity as one potential mechanism for these effects. We have previously reported on the acute and short-term effects of this drug and we report on the medium-term effects herein. MethodsPatients were recruited among those beginning bevacizumab for the treatment of metastatic colon cancer. Demographics and clinical characteristics of the patients at the time of enrollment were collected. A 10-minute high-resolution ECG was recorded prior to a first dose of bevacizumab and analysed for heart rate variability (HRV), a marker of ANS dysfunction. Patients returned 6 months after their initial visit and had a repeat 10-minute ECG recording. Paired t-tests were used to compare baseline HRV recordings to those recorded after a 6-month course of the drug. Patients were recruited among those beginning bevacizumab for the treatment of metastatic colon cancer. Demographics and clinical characteristics of the patients at the time of enrollment were collected. A 10-minute high-resolution ECG was recorded prior to a first dose of bevacizumab and analysed for heart rate variability (HRV), a marker of ANS dysfunction. Patients returned 6 months after their initial visit and had a repeat 10-minute ECG recording. Paired t-tests were used to compare baseline HRV recordings to those recorded after a 6-month course of the drug. ResultsTen patients without a significant cardiac history were enrolled. Seven patients survived to 6 months of follow up and are included in this analysis. Mean patient age was 64 years and 6 were male. All were in sinus rhythm and had normal systolic function by echocardiography. Changes in HRV indices are reported in Table 1. Ten patients without a significant cardiac history were enrolled. Seven patients survived to 6 months of follow up and are included in this analysis. Mean patient age was 64 years and 6 were male. All were in sinus rhythm and had normal systolic function by echocardiography. Changes in HRV indices are reported in Table 1. ConclusionKGH Garfield Kelly Award, KGH/HDH Cardiac Program Award KGH Garfield Kelly Award, KGH/HDH Cardiac Program Award

Plasma FGF23 levels and heart rate variability in patients with stage 5 CKD.

Fibroblast growth factor 23(FGF23) is a bone-derived hormone which regulates mineral homeostasis but may also have a role in cardiovascular disease. Here, we found that higher plasma FGF23 was independently associated with decreased heart rate variability in stage 5 CKD patients and parathyroidectomy may reverse these abnormal indicators. Lower heart rate variability (HRV) in patients with chronic kidney disease (CKD) compared with healthy controls is associated with increased risk of cardiovascular disease (CVD). Higher levels of plasma FGF23 also predict higher risk of CVD. Here, we aimed to evaluate the relationship between plasma FGF23 levels and HRV in patients with stage 5 CKD and to investigate longitudinal changes of them together with the correlation between their changes in two severe secondary hyperparathyroidism (SHPT) subgroups with successful parathyroidectomy (PTX) and persistent SHPT. This cross-sectional study included 100 stage 5 CKD patients, 78 controls, and a prospective study in two PTX subgroups classified as successful PTX (n = 24) and persistent SHPT (n = 4) follow-up. Blood examination and 24-h Holter monitoring for HRV were measured. Most HRV indices were lower in stage 5 CKD patients than in healthy controls, and plasma FGF23 levels were higher. In multivariate stepwise regression models, levels of plasma FGF23 and serum parathyroid hormone (PTH) were correlated with HRV. The successful PTX subgroup had significant improvements over baseline in HRV indices. Persistent SHPT subgroup had numerically similar changes in HRV indices. However, plasma FGF23 levels decreased in both subgroups. Plasma FGF23 levels were higher in CKD patients than in controls, much higher in patients with severe SHPT. FGF23 was independently associated with decreased HRV in stage 5 CKD. Successful PTX may reverse these abnormal indicators and contribute to decreases in the risk of cardiovascular disease.

ACUTE EFFECTS OF ALCOHOL ON HEART RATE VARIABILITY: TIME-RELATED CHANGES AND GENDER DIFFERENCE

Objectives: Alcohol consumption is associated with a broad array of physiologic and behavioral effects including changes in cardiac autonomic activity. In the present study, time-related acute effects of alcohol have been characterized and compared between genders. Methods: A total of 30 healthy subjects (15 males and 15 females) were enrolled in this study. The red wine was given to each subject at a dosage of 0.27 g of pure ethanol per kilogram of body weight. 5-min electrocardiograms (ECGs) were collected before (BR) and at 15 min (P15), 30 min (P30), 45 min (P45) and 60 min (P60) after alcohol intake. Time- and frequency-domain analysis of heart rate variability (HRV) was performed. The time-domain HRV indices include mean RR interval, pNN50, SDNN and RMSSD. The low- (LF: 0.04 to 0.15 Hz) and high-frequency (HF: 0.15 to 0.4 Hz) components along with LF/HF ratio were calculated for frequency-domain analysis of HRV. HRV was also analyzed by mathematical models, e.g. Poincaré plot, which uses a nonlinear geometric representation of change in interbeat heart rate. Poincaré plots indices, SD1, SD2, SD1/SD2 ratio and r RR , were applied in this study for HRV assessment. Results: Alcohol intake was associated with decreased HRV in both time and frequency domains. The lowest HRV was observed 30–40 min after the intake of alcohol. The alcohol intake also caused the decrease of Poincaré plots indices (SD1 and SD1/SD2 in P30, P40 and P60, and r RR in P45), accompanied with a narrower plot area. The changes of HRV indices differed by gender. The male subjects demonstrated a greater decrease of parameters measured in this study compared to the female subjects. Conclusion: Acute effects of alcohol ingestion resulted in reductions in HRV, indicating impaired cardiac autonomic nervous activity. Autonomic nervous activity in the females was less dampened by the alcohol compared to the males.

Are the cardiovascular side effects of bevacizumab caused by autonomic nervous system toxicity?

429 Background: Bevacizumab, a monoclonal antibody that inhibits the activity of vascular endothelial growth factor, has demonstrated activity against several malignancies. Reported adverse effects include hypertension, endothelial dysfunction, and heart failure. Animal models have suggested ANS toxicity as the mechanism. This pilot study investigates the effects of bevacizumab on short and long-term ANS function using a pre-post intervention design protocol. We report on the acute effects herein. Methods: Patients were recruited among those starting bevacizumab for colon cancer. A 10-minute ECG was recorded prior to, during, and following a first dose and analysed for heart rate variability (HRV), a marker of ANS dysfunction. The HRV values were compared using paired t-tests and repeated measures ANOVA. Plasma hormones were drawn before and after infusion and compared using paired t-tests. Results: Nine patients without a cardiac history were tested. Mean age was 63 years and 5 were male. All were in sinus rhythm with normal systolic function by echo. The Table reports changes in HRV indices and plasma hormones. Conclusions: Acute administration of bevacizumab produced a statistically significant decrease in plasma aldosterone and was associated with a trend towards decreases in plasma norepinephrine and the low/high frequency domain ratio of HRV. These changes may be signs of an early ANS imbalance. Both a larger patient series and longer follow-up are planned to characterize the effects of bevacizumab on the ANS. [Table: see text]

Effect of endotoxin on heart rate dynamics in rats with cirrhosis

Reduced heart rate variability (HRV) is a hallmark of systemic inflammation which carries negative prognostic information in sepsis. Decreased HRV is associated with partial uncoupling of cardiac pacemaker from cholinergic neural control during systemic inflammation. Sepsis is a common complication in liver cirrhosis with high mortality. The present study was aimed to explore the hypothesis that endotoxin uncouples cardiac pacemaker from autonomic neural control and reduces HRV in an experimental model of cirrhosis. Cirrhosis was induced by surgical ligation of the bile duct in rats. Cirrhotic rats were given intraperitoneal injection of either saline or lipopolysaccharide (endotoxin, 1mg/kg). Changes in HRV indices were studied in conscious rats using implanted telemetric probes. The atria were isolated and chronotropic responsiveness to cholinergic stimulation was assessed in vitro. Endotoxin injection induced a significant tachycardia and decreased short-term and long-term HRV indices in control rats. However, endotoxin was unable to increase heart rate in cirrhotic animals. In contrast with control rats, endotoxin induced biphasic changes in short-term HRV in cirrhotic rats. Acute endotoxin challenge reduced long-term HRV with 60-min delay in comparison with control animals. Endotoxin injection was associated with a significant hypo-responsiveness to cholinergic stimulation in control rats in vitro. Endotoxin did not change atrial chronotropic responsiveness to cholinergic stimulation in cirrhotic rats. Our data shows that cirrhosis is associated with development of tolerance to cardiac chronotropic effect of endotoxin in rats.

Metabolic syndrome, physical activity and cardiac autonomic function

Our primary aim was to investigate the associations that components of metabolic syndrome and physical activity have with cardiac autonomic nervous system activity as estimated by heart rate variability (HRV) in young adults free of metabolic abnormalities. We also aimed to identify predictors of 3-year changes in HRV. Physical activity was assessed annually in 163 healthy participants over 3 years (2008-2010). Components of metabolic syndrome measured annually were; waist circumference, systolic blood pressure, high-density lipoprotein, triglycerides, glucose, and C-reactive protein. A linear mixed regression model was used to assess associations between HRV, metabolic syndrome components and physical activity. Linear regression was used to identify predictors of changes in HRV. Metabolic syndrome components were negatively associated with HRV indices and higher heart rate, while physical activity was associated with higher HRV and lower heart rate. Physical activity and inflammation were predictors of positive and negative changes in HRV indices, respectively. In participants without significant metabolic abnormalities, metabolic syndrome components were still associated with less favourable HRV profiles. Physical activity and inflammation were both able to predict changes in HRV, albeit in different directions. It appears that the process of autonomic dysfunction starts at a young age and may be mediated in part by inflammation. Metabolic syndrome prevalence is increasing in younger populations; promoting the metabolic and autonomic benefits of exercise remains imperative.

저항성 운동이 심박 변이도에 미치는 영향

The Acute resistance exercise has been suggested to induce abnormal cardiac autonomic function reflected by reduced heart rate variability(HRV). However, investigations have not controlled for geometrical condition, which can modulate HRV. Accordingly, the aims of this experiment were to investigate each effect of acute resistance exercises on HRV. 8 young (21.3±0.6years) healthy males performed, in random order, arm curl, bench press, and squat to volitional fatigue(within 8~12 RM) respectively. Electrocardiogram data were collected during 5 min periods in the sitting position, at rest before exercise and after exercise. Measures of heart rate variability, obtained from both time- and frequency domain analysis of 5min ECG recording were as follows: mean RR interval and its standard deviation(SDNN), the mean square successive differences(RMSSD), the low and high frequency components which were calculated as normalized units and their ratio(LF/HF ratio). Analysis of HRV revealed a significant increase in sympathetic activity and a significant decrease in parasympathetic activity following each resistance exercises. In comparison of exercises, bench press resulted in significantly greater changes of HRV indices than squat, and this change are similar between squat and arm curl despite differences in force production(muscle size). These findings suggest that in resistance exercise, upper exercises results in higher change in cardiac autonomic control than lower exercises.

Interplay Between the Acute Inflammatory Response and Heart Rate Variability in Healthy Human Volunteers

The autonomic nervous system and the inflammatory response are intimately linked. Heart rate variability (HRV) analysis is a widely used method to assess cardiac autonomic nervous system activity, and changes in HRV indices may correlate with inflammatory markers. Here, we investigated whether baseline HRV predicts the acute inflammatory response to endotoxin. Second, we investigated whether the magnitude of the inflammatory response correlated with HRV alterations. Forty healthy volunteers received a single intravenous bolus of 2 ng/kg endotoxin (LPS, derived from Escherichia coli O:113). Of these, 12 healthy volunteers were administered LPS again 2 weeks later. Heart rate variability was determined at baseline (just before LPS administration) and hourly thereafter until 8 h after LPS administration. Plasma cytokine levels were determined at various time points. Baseline HRV indices did not correlate with the magnitude of the LPS-induced inflammatory response. Despite large alterations in HRV after LPS administration, the extent of the inflammatory response did not correlate with the magnitude of HRV changes. In subjects who were administered LPS twice, inflammatory cytokines were markedly attenuated after the second LPS administration, whereas LPS-induced HRV alterations were similar. Heart rate variability indices do not predict the acute inflammatory response in a standardized model of systemic inflammation. Although the acute inflammatory response results in HRV changes, no correlations with inflammatory cytokines were observed. Therefore, the magnitude of endotoxemia-related HRV changes does not reflect the extent of the inflammatory response.