Cardiac Autonomic Function Research Articles

Impact of atrial fibrillation on cardiac autonomic function in elderly patients

Abstract Introduction Cardiac autonomic dysfunction has been linked to an increased risk of mortality (1), stroke and silent brain lesions (2) and cognitive impairment (3) in patients with atrial fibrillation (AF). However, the impact of AF on cardiac autonomic function is poorly understood. Purpose We aimed to explore the impact of AF on cardiac autonomic function by comparing AF patients with a matched control cohort without AF. Methods We enrolled patients with and without AF from two ongoing, prospective, multicenter cohort studies (Swiss-AF Cohort and Swiss-AF Control) if they had a high-resolution 16-lead resting ECG recording in sinus rhythm for a duration of 5 minutes at baseline visit. Cardiac autonomic function was quantified by periodic repolarization dynamics (PRD), a marker of repolarization instability associated with sympathetic activity. PRD was quantified by means of wavelet analysis, as validated previously (4). Cardiac autonomic dysfunction was defined present if PRD exceeded the established cut-off of 10.0 deg2 (5). We built multivariable adjusted linear and logistic regression models to explore the association of AF with PRD and cardiac autonomic dysfunction. Results We included 2077 patients, 1113 (54%) from the AF cohort and 964 (46%) from the matched non-AF cohort. Baseline characteristics were well balanced between the groups (mean age 71 vs. 73 years in patients with and without AF, mean CHA2DS2-VASc score 3.0 vs. 3.5, female sex 31.3% vs. 36.6%). The median PRD was 18.2 deg2 (IQR 9.9-25.4) in patients with AF and 15.8 deg2 (IQR 8.1 -23.0) in patients without AF (p<0.001, Figure). 832 (75%) of the AF patients suffered from cardiac autonomic dysfunction, vs. 656 (68%) of the non-AF patients (p<0.001). Multivariable adjusted linear regression analysis revealed an independent association of AF with continuous levels of PRD (beta-coefficient -1.57, 95% CI -2.64 - -0.488, p=0.004). Further, AF was independently associated with the presence of cardiac autonomic dysfunction (Odds Ratio 1.48, 95% CI 1.18-1.87, p<0.001, Table). Conclusion In this cross-sectional analysis of a patient population with and without AF, AF was independently associated with increased PRD values, reflecting sympathetic predominance, and with the presence of cardiac autonomic dysfunction. These findings implicate a relevant role of AF in the development of cardiac autonomic dysfunction in elderly patients.Figure

Cardiac autonomic changes after stroke

Abstract Introduction There is a highly complex and clinically important relationship between the cardiac and the nervous system, called the heart-brain axis [1]. Therefore, acute brain damage may lead to alterations in cardiac function due to changes in the autonomic nervous system[2,3]. Novel computerised biosignal analysis techniques and advanced biosignal assessment could provide a valuable tool to sensitively analyse cardiac autonomic function (CAF). CAF can be characterized by two complementary digital biomarkers, periodic repolariation dynamics (PRD) and deceleration capacity (DC). The aim of this study was to determine CAF by means of PRD and DC in patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA) and to analyze them according to their relationship with specific cardiac (high-sensitive Troponin T (hsTnT) and N-terminal pro-B-type natriuretic peptide (NT-pro BNP)) and stroke (location, type, severity) characteristics. Methoden / Methods Between February 22, 2021, and May 5, 2023, 282 patients after an AIS or TIA were enrolled in the study. During the inpatient stay, all relevant parameters were recorded and stored in a database. To assess CAF, a 30-minute biosignal measurement was performed with a high resolution (1kHz) electrocardiogram (ECG). Cardiac autonomic biomarkers, PRD and DC, were calculated semiautomatically afterwards from patients. Results Fifteen ECGs were excluded due to poor recording quality. Consequently, data from 261 AIS and 21 TIA patients were analyzed. A total of 105 patients (37.2 %) had pathological PRD (≥ 5.75 deg2) and/or DC (≤ 2.5 ms), 78 patients (27.7 %) had pathological PRD, and 57 patients (20.2 %) had pathological DC. The median PRD was 3.13 deg2 and the median DC was 5.30 ms (see Figure). There were no significant differences in the distribution of PRD and DC between male and female patients (PRD p = 0.38, DC p = 0.30), and between AIS and TIA patients (PRD p = 0.13, DC p = 0.66). Patients with middle cerebral artery (MCA) infarction had significantly higher median PRD values (3.56 deg2 [IQR 1.51 - 6.59 ] vs. 2.81 deg2 [IQR 1.15 - 5.99], p = 0.047) and lower median DC values (4.66 ms [IQR 2.65 – 7.76] vs. 6.11 ms [IQR 3.15 – 10.61], p = 0.011) than patients with stroke located in another cerebral regions (see Figure). Patients with pathological PRD or DC had significantly higher hsTnT (13.50 ng/l [IQR 9.7 – 24.1] vs. 11.05 ng/l [ IQR 7.13 – 16.23], p < 0.001) and NT-pro BNP (269.00 ng/l [IQR 117.50 – 687.00] vs. 125.50 ng/l [IQR 57.00 – 288.25], p < 0.001) values. Conclusions The study showed that a considerable proportion, more than one third of all patients, had evidence of cardiac autonomic dysfunction after acute cerebral ischaemia. Of particular interest, PRD was higher and DC was lower in patients with MCA ischaemia, reflecting a potentially higher cardiac risk profile. Cardiac autonomic dysfunction was also associated with increased hsTnT and NT-proBNP levels.

Cardiac autonomic dysfunction in Takotsubo cardiomyopathy: an observational study

Abstract Takotsubo syndrome (TTS), commonly perceived as a benign and reversible condition has received attention due to emerging registry data revealing its prognosis to be comparable to acute coronary syndrome (ACS). Following ACS, a notable subset of patients develops autonomic dysfunction, whith unfavourable prognostic implications. Periodic repolarization dynamics (PRD) and deceleration capacity (DC), derived from ECG signals, are parameters capable of quantifying cardiac autonomic function. In this study, we aimed to assess autonomic dysfunction in patients with TTC in comparison to ST-elevation myocardial infarction (STEMI) patients. Consecutive patients diagnosed with TTS were prospectively recruited into an observational, single-centre cohort study. All patients underwent a 30-minute high-resolution ecg recording. Subsequent recordings were conducted at 4 and 12 months post-acute event. PRD and DC as markers for sympathetic and parasympathetic activity, respectively, were assessed using established methods. The control group comprised patients with STEMI. Statistical comparisons between groups were performed using the Mann-Whitney U-test, with a corrected significance level for multiple testing of α< .017. Between July 2021 and December 2023, 57 patients diagnosed with TTS were recruited (interquartile range [IQR]) 69.0 years (62.0-78.0), 98.3% women. A control group was derived from a pre-existing cohort of STEMI patients, matched through propensity score matching to adjust for age and sex (median age [IQR]: 69.0 [59.0-76.0] years, 98.3% women). At baseline, there was no significant difference in PRD between TTS patients and controls (median [IQR]: TTS: 5.28deg² [3.43-9.93], STEMI: 4.40deg² [2.24-7.21]; p = .04). However, at 4 months post-acute event, PRD was notably higher in TTS patients compared to controls (median [IQR]: TTS: 5.20deg² [2.71-8.17], STEMI: 2.63deg² [1.86-4.92]; p = .011). Interestingly, at 12-month follow-up, PRD in TTS patients did not differ from that of controls (median [IQR]: TTS: 4.55deg² [2.89-8.40], STEMI: 4.15deg² [2.42-6.85]; p = .68). Regarding DC, no significant differences were observed between TTS and STEMI patients at any time point (baseline: median [IQR]: TTS: 3.95 ms [2.27-5.51], STEMI: 3.52 ms [2.30-7.24], p = .51; 4 months: median [IQR]: TTS: 6.63 ms [4.59-8.64], STEMI: 7.41 ms [4.63-9.25], p = .39; 12 months: median [IQR]: TTS: 4.98 ms [4.19-6.67], STEMI: 7.48 ms [4.92-10.28], p = .17). Patients with TTS show substantial signs of cardiac autonomic dysfunction, similar or even higher than acute STEMI patients. This dysfunction persists even up to 4 months after the acute event, whereas STEMI patients show recovery of autonomic function in this 4 month period. DC remained consistent between TTS and STEMI patients across all time points. Further research elucidating the long-term implications of these autonomic alterations is warranted to refine risk stratification and therapeutic strategies in TTS management.

Comparative Analysis of Heart Rate Variability and Arterial Stiffness in Elite Male Athletes after COVID-19.

This study investigated the long-term cardiovascular effects of coronavirus disease (COVID-19) in elite male athletes by comparing the heart rate variability (HRV), arterial stiffness, and other cardiovascular parameters between those with and without prior COVID-19 infection. Methods: This cross-sectional study evaluated 120 elite male athletes (60 post COVID-19, 60 controls) using anthropometric measurements, body composition analysis, pulmonary function tests, HRV analysis, arterial stiffness assessments, hemodynamic monitoring, and microcirculatory function tests. Results: Athletes post COVID-19 showed significantly higher lean mass (p = 0.007), forced vital capacity (p = 0.001), and forced expiratory volume in 1 s (p = 0.007) than controls. HRV parameters did not significantly differ between the groups. Post-COVID-19 athletes exhibited peripheral vascular resistance (p = 0.048) and reflection index (p = 0.038). No significant differences were observed in the blood pressure, cardiac output, oxygen saturation, or microcirculatory oxygen absorption. Conclusions: Elite male athletes showed notable cardiovascular resilience after COVID-19, with only minor differences in vascular function. The maintained cardiac autonomic function and improved lung parameters in post-COVID-19 athletes suggests an adaptive response. These findings support the cardiovascular health of elite athletes following COVID-19 but emphasize the importance of continued monitoring.

Impact of neonatal hyperoxia on adult cardiac autonomic function in rats: Role of angiotensin II type 1 receptor activation

Individuals born preterm present altered cardiac autonomic function, a risk factor to heart diseases. Neonatal renin-angiotensin-system activation contributes to adult cardiomyopathy in rats exposed to neonatal hyperoxia, a well-established model of preterm birth-related conditions. Central angiotensin II receptor activation is a key modulator of the autonomic drive to the heart. Whether neonatal hyperoxia leads to alteration of the cardiac autonomic function through activation of the angiotensin II receptor type 1 (AT1) is unknown and was examined in the present study.Sprague-Dawley pups were exposed to hyperoxia or room air from postnatal days 3–10. AT1 antagonist losartan or water was given orally postnatal days 8–10. Blood pressure, autonomic function, left ventricular sympathetic innervation, β-adrenergic-receptors expression, and AT1 expression in the solitary-tract-nucleus were examined in adult rats.Neonatal hyperoxia led to loss of day-night blood pressure variation, decreased heart rate variability, increased sympathovagal balance, increased AT1 expression in the solitary-tract, decreased left ventricle sympathetic innervation, and increased β1-adrenergic-receptor protein expression. Losartan prevented the autonomic changes and AT1 expression in the solitary-tract but did not impact the loss of circadian blood pressure variation nor the changes in sympathetic innervation and in β1-adrenergic-receptor expression.In conclusion, neonatal hyperoxia leads to both central autonomic and cardiac sympathetic changes, partly programmed by neonatal activation of the renin-angiotensin system.

Can Muscle Strength Fitness Offset The Detrimental Consequences Of Long Covid-19 Conditions On Cardiac Autonomic Function?

Can Muscle Strength Fitness Offset The Detrimental Consequences Of Long Covid-19 Conditions On Cardiac Autonomic Function?

Effect of lemongrass (Cymbopogoncitratus) essential oil on cardiac autonomic function in female Generalized Anxiety Disorder:A poincaré analysis of heart rate variability

Background:Generalized anxiety disorder (GAD) is a worldwide, one of most prevalent mental disorder and associated with autonomic dysfunction. Poincaré plot of heart rate variability (HRV) is anonlinear method to assess cardiac autonomic nerve function (CANF).Lemongrass (Cymbopogoncitratus) essential oil (LEO) has been reported with anxiolytic effect and autonomic improvement in human. Objective: To assess the effect of LEO inhalation on CANF in female patients with GAD by analysis of poincaré plot of HRV.Method: This Quasi experimental study was conducted on 60 newly diagnosed female GAD patients with 20-40 years of age. Among them, 30 patients were treated with LEO inhalation for 15 min for once a week for one month (30days)along conventional treatment and 30 patients were without LEO inhalation and continued only conventional treatment for 30days.Thirty (30) apparently healthy subjects were control group.HRV data of all patients and control were recorded at baseline and after 30days of intervention or follow up respectively. HRV was recorded by a data acquisition device, Power Lab 8/35 and Poincaré plot analysis was done by lab chart software. For statistical analysis ANOVA followed by post-hoc test and paired sample ‘t’ test were done.Results: In this study, at baseline, the standard deviation of the short-term RR interval variability (minor axis of the cloud, SD1),the standard deviation of the long-term RR interval variability (major axis of the cloud, SD2) and SD1/SD2 were found significantly lower (p<0.001) in all GAD patients compared to control group. After 30 days of intervention with LOE, significant increase of SD1(p<0.001) and SD2, SD1/SD2 (p<0.01) were found in GAD patients whereas no significant difference was found in patients without LEO after 30 days. Moreover, significantly higher values of SD1 and SD2 were observed in GAD patients after aroma therapy with LEO compared to GAD patients not under aroma therapy. Furthermore, LEO could restore the BP of the GAD to the control level. Conclusion: This study concluded that, aromatherapy with LEO inhalation may be effective to improve cardiac autonomic dysfunction in female GAD patients. J Bangladesh Soc Physiol 2023;18(1): 19-26

Effect of slow breathing exercise on heart rate variability: A non linear analysis in female major depressive disorder patients

Background: Major depressive disorder (MDD) is a mental health problem, associated with cardiac autonomic dysfunction. Cardiac autonomic function (CANF) can be assessed by non linear analysis of heart rate variability (HRV), a simple non-invasive software based analytical method. Yoga based slow breathing exercise (SBE) has role to improve autonomic dysfunction in some disease condition. Objective: To observe the effect of SBE on non linear measures of HRV in newly diagnosed female MDD patients. Methods: The quasi-experimental study was conducted in 2023 on sixty (60) newly diagnosed female MDD patients of 20-40 years aged, collected from the Department of Psychiatry, Bangabandhu Sheikh Mujib Medical University (BSMMU). Among them 30 were assigned with SBE and remaining 30 patients without SBE were followed up after 90 days. Both patient groups received conventional treatment during this period. Thirty apparently healthy female subjects with similar age & BMI were included as control for comparison and they did not perform breathing exercise. Data were taken at baseline and after 90 days in all the subjects. CANF was assessed by analysing non linear (poincare plot) of HRV by using ECG based data acquisition device, Power lab 8/35. Data were expressed as mean±SD. For statistical analysis, ANOVA followed by post hoc Bonferroni test and paired sample “t” test were used. Results: At baseline pulse rate and BP were significantly lower in both group of MDD patients compared to control. The pre-intervention values of standard deviation of short term RR interval variability (SD1), standard deviation of long term RR interval variability (SD2) and ratio of short term and long term RR interval variability (SD1/SD2) were found significantly (p< 0.001) lower in MDD patients compared to healthy control. Following 90 days of SBE, significant (p< 0.001, p< 0.05) rise of these poincare plot parameters was noted in MDD patients whereas no significant changes of these parameters were observed in patients without SBE after 90 days of follow-up. Moreover, the pulse BP almost reached control level though the non linear parameters were still below control level after 3 months of SBE.. Conclusion: Autonomic dysfunction occured in MDD patients SBE can improve cardiac autonomic dysfunction and sympathovagal balance in female MDD patients. J Bangladesh Soc Physiol 2023;18(2): 45-52

Association of cardiac autonomic nerve function with serum zinc, calcium and magnesium in female hypothyroid patients

Background: Hypothyroidism is related to impaired cardiac autonomic nerve activity with altered levels of serum Zinc (Zn), Calcium (Ca) ‍and Magnesium (Mg).Altered Serum Zn,Caand Mg levels are also associated with autonomic imbalance and may raise cardiovascular risk.Heart rate variability (HRV) is an important marker for assessing cardiac autonomic nerve function(CANF). Objectives: To evaluate the association of serum Zn, Cal and Mglevels withCANF in female hypothyroid patients. Methods: This analytical cross-sectional study was conducted on 40 female hypothyroid patients aged 18-45 years. Thirty apparently healthy women were control. Serum Zn, Ca and Mg levels were estimated by autoanalyzer and CANF was assessed by time domain analysis of HRV recorded by Power Lab 8/35 AD Instruments, Australia. Statistical analysis was done by Independent sample‘t’ test, One way ANOVA followed by post-hoc Bonferroni test and Pearson’s correlation coefficient test. Results: Among time domain parameters of HRV, standard deviation of the RR intervals (SDRR), coefficient variation of RR interval (CVRR), SD rate, standard deviation of the difference between successive RR intervals (SDSD), square root of mean squared differences of successive RR intervals (RMSSD), proportion of RR interval with duration >50 ms (pRR50%) were significantly lower (p<0.05) in all hypothyroid patients as compared to control. On correlation analysis, serum Zn, Ca and Mg were significantly positively correlated with SDSD(p<0.01, p<0.001,p<0.01) RMSSD(p<0.01, p<0.001, p<0.01), pRR50%(p<0.01, p<0.01, p<0.05)and serum Ca was also positively correlated with SDRR(p<0.05) in hypothyroid patients. Conclusion:Serum ZnCa and Mg were associated with cardiac autonomic dysfunction. in female hypothyroid patients. J Bangladesh Soc Physiol 2023;18(1): 27-34

Slow breathing exercise improves cardiac autonomic tone in hypothyroid patients: a frequency domain analysis of HRV

Background: Hypothyroidism is associated with autonomic dysfunction and oxidative stress. Slow breathing exercise (SBE), a yoga-based relaxation technique, improves cardiac autonomic nerve function by changing sympathetic or parasympathetic activity. Objective: To assess the effect of SBEon cardiac autonomic tone and in hypothyroid patients. Methods: This non randomized controlled trial was conducted on 50 newly diagnosed drug naive female hypothyroid patients (18-45 years of age)recruited from the outpatient department of the Department of Endocrinology, Bangabandhu Sheikh Mujib Medical University,(BSMMU), Shahbag, Dhaka. Twenty five apparently healthy female subjects formed control group. . Among the 50 hypothyroid patients, 25 were consecutively assigned with SBE for 90 days (Group SBE) and the remaining 25 patients were without SBE and followed up after 90 days (Group NSBE). Both groups of patients received treatment with thyroid hormone replacement during their follow up period. Control group did not perform SBE or any other exercise. Data were recorded at baseline(Day 0) and after 90 days in all the subjects. Based on data recording period SBE group was designated as SBE0(at day 0 or pre intervention)and SBE90(at day 90 or post intervention). Similarly, NSBE0(day 0) and NSBE90 (day 90) and control group was also designated as control0 (day 0) and control90 (day 90).Resting cardic autonomic tonic activity was assessed by frequency domain analysis of Heart Rate Variability(HRV). HRV data were recorded by a digital data acquisition device Power Lab, AD Instrument Australia. Data were expressed as mean±SD. For statistical analysis, ANOVA followed by post hoc Bonferroni test and paired sample “t” test were done. Results: At baseline i.e. at day 0 before follow up, diastolic blood pressure (DBP) (p<0.05), low frequency in normalized unit (LF norm) (p<0.001), low frequency/high frequency ratio (LF/HF) (p<0.001) were significantly higher and total power (TP) (p<0.001), low frequency power (LF power) (p<0.01), high frequency power (HF power) (p<0.001), high frequency power in normalized unit (HF norm) (p<0.001) were significantly lower in hypothyroid patients (group SBE0and NSBE0 ) compared to healthy control (group control0). After 90 days of intervention with SBE, SBP, DBP, LF norm, LF/HF ratio decreased significantly and TP, HF power, HF norm increased significantly in group SBE90 compared to SBE0. Whereas, in group NSBE90, after 90 days of follow up, LF norm, LF/HF ratio decreased significantly and HF power, HF norm increased significantly compared to NSBE0. Again, after 90 days of follow up/SBEHF norm were significantly higher and LF norm, LF/HF ratio were significantly lower in SBE90 compared to NSBE90. In addition, significant difference was present in all these parameters between NSBE90 and control90. Also, after 90 days of SBELF norm, HF norm and LF/HF ratio was not significantly different from control. Conclusions: Based on these results, it can be concluded that autonomic dysfunction characterized by reduced vagal tone and sympathetic hyperactivity occurred in drug naïve hypothyroid patients. In addition, thyroid hormone replacement therapy improved autonomic dysfunction by increasing parasympathetic and decreasing sympathetic tonic activity. Moreover, SBE caused further improvement of autonomic dysfunction and could restore sympathovagal balance to its normal state in these patients. J Bangladesh Soc Physiol 2023;18(1): 9-18

Correlation of serum zinc and magnesium with reduced heart rate variability in male Parkinson’s disease patients

Background: Parkinson’s disease (PD) is a neurological disorder associated with altered cardiac autonomic function. Heart rate variability (HRV) analysis is a tool to assess the cardiac autonomic status. Altered serum zinc (Zn) and magnesium (Mg) levels are observed in PD. The serum Zn and Mg alteration is associated with nerve function impairment. Objective: To evaluate the relationship between serum zinc, magnesium, and time domain measures of HRV in male patients with PD. Methods: This observational analytical cross-sectional study was conducted in 2023on 30 newly diagnosed male PD patients aged 50-60 years. In this study, 30 healthy volunteers were the control. The 30 patients were divided into different categories based on serum mineral levels. The HRV was recorded by Power Lab 8/35, AD Instruments, Australia and the time domain measures of HRV were used in data analysis. The serum Zn and Mg levels were measured by atomic absorption spectrophotometry. Independent sample ‘t’ test and Pearson’s correlation coefficient test were used for statistical analysis and p<0.05 was considered statistical significance. Results: Significantly higher mean HR (Heart rate) (p<0.01) and significantly lower mean RR (Normal to normal QRS complex) interval,CVRR (Coefficient variation of RR interval) (p<0.01), SDRR (Standard deviation of the RR intervals), SDSD (Standard deviation of the difference between successive RR intervals), RMSSD (Square root of mean squared differences of successive RR intervals), pRR50% (Proportion of RR interval with duration >50 ms) (p<0.001)were observed in PD patients compared to control. In PD patients, significantly lower (p<0.001) serum Zn and significantly higher (p<0.01) serum Mg were observed compared to control. In addition,significant decrement was observed in SDRR, CVRR (p<0.05), SDSD, RMSSD, and pRR50% (p<0.01) in hypozincemic PD patients compared to normozincemic patients. On correlation analysis, significant positive correlations of serum Zn were observed with SDRR (p<0.05),SDSD (p<0.001), RMSSD (p<0.001) and pRR50% (p<0.01). Moreover,serum Mg was positively correlated with SDRR (p<0.05) in PD patients. Conclusion: Hypozincemia and magnesium were directly related to reduced HRV in male PD patients. J Bangladesh Soc Physiol 2023;18(2): 63-71

Impact of age and sex on heart rate variability and cardiometabolic function in healthy adults

Heart rate variability (HRV) is a non-invasive measure of cardiac autonomic function. A clearer understanding as to whether resting autonomic function represented by HRV could be associated with changes in peak exercise cardiac function remains unanswered. This study evaluated the effect of age and sex on HRV, cardiometabolic function, and determined the correlation between HRV and cardiac function in healthy individuals. Sixty-eight participants (age range: 19–78 years old, females, n = 28) were recruited. Participants were stratified according to age (younger (<40 years old, n = 43, females, n = 17) and older age groups (>55 years old, n = 25, females, n = 11). Firstly, HRV was measured using non-invasive impedance cardiography method (TaskForce, CNSystems, Graz, Austria) and recorded at rest (supine position) for 30 min. HRV measures included: low frequency (LF) power, high frequency (HF) power (both normalised (nu) and absolute units (ms2)) and LF/HF ratio. Participants then completed a progressive cardiorespiratory exercise test using a semi-recumbent cycle ergometer (Corival, Lode, Groningen, Netherlands) with simultaneous gas exchange measurements (Metalyzer 3B, Cortex, Leipzig, Germany). Cardiac function was represented by peak exercise cardiac power output index (CPO). After controlling for body mass index and physical activity, males had significantly higher mean vales of RR interval than females (males = 1043 ± 165; females = 952 ± 128 ms, p = 0.02). There was no significant main effect of age, sex or their interaction on any of the other HRV measures. In younger and older females, resting RR interval had a significant relationship with peak exercise CPO (young females: r = 0.54, p < 0.05; old females: r = 0.81, p < 0.01). There was also a significant relationship between resting HF power and peak exercise CPO in younger females (r = 0.70, p < 0.01). HRV was not influenced by age but RR interval was associated with peak exercise CPO in females regardless of age, whilst HF power was significantly associated with CPO in younger females only.

Adiposity and cardiac autonomic function in children with a family history of obesity

Adiposity and cardiac autonomic function in children with a family history of obesity

Improved heart rate variability in postmenopausal women following short-term combined exercise training

Imbalances in cardiac autonomic nervous systems are associated with cardiovascular risk factors and poor cardiac outcomes. Heart rate variability (HRV) is a practical and reproducible measure of cardiac autonomic nervous system function. Exercise training promotes positive adjustments in HRV. However, previous studies have reported mixed results. Therefore, this study aimed to investigate the effects of short-term combined exercise training on heart rate variability in post-menopausal women. Thirty-four women aged 50-80 years, at least 12 months post-menopause, were divided into a control (CON) group and an exercise (EX) training group. The participants in the exercise group underwent a 2-week of combined exercise program consisting of aerobic, strength, flexibility, and balance exercises. HRV was recorded using an Actiheart device, before and after the final exercise intervention in a sitting position. The significant main effects of time and group were found in the parameter of SDNN (p time = 0.039; p group = 0.026). Post-hoc analysis showed a borderline increase in SDNN in the EX group (POST: 48.79 ± 17.88 VS 44.54 ± 17.39, p = 0.055). No significant change was observed in the CON group (POST: 35.55 ± 13.51 VS 33.17 ± 8.74, p = 0.288). Statistical analysis of other HRV components revealed no significant results (all P &gt; 0.05). In conclusion, a 2-week of combined exercise training program, including aerobic, resistance, balance, and flexibility exercises improves global cardiac autonomic function in post-menopausal women. Keywords: combined exercise training, heart rate variability, blood pressure, menopause, and women

Pupil to limbus diameter ratio as an emerging autonomic function test and its correlation with anthropometric parameters in different phases of menstrual cycle

The menstrual cycle is a physiological change in normal females, indicating the proper functioning of both endocrine and reproductive health. The pupil to limbus diameter (PLD) ratio is defined as the ratio of pupil diameter measured at an axial plane to the limbus diameter measured at the same or a parallel axial plane. Alterations in estrogen and progesterone levels may influence cardiac autonomic functions. This study aimed to correlate the PLD ratio with anthropometric parameters, such as body mass index (BMI) and waist circumference (WC), during different phases of the menstrual cycle among medical students.Methods: A cross-sectional study was conducted among first- and second-year female MBBS students aged 17 to 22 years. Anthropometric parameters, including height, weight, BMI, and WC, were measured for all participants. Eye photographs were taken during the follicular and luteal phases of the menstrual cycle, and the diameters were measured manually using the two-box method. The PLD ratios for both eyes showed a significant positive correlation with BMI (right eye: r = 0.682, p &lt; 0.000; left eye: r = 0.430, p &lt; 0.000) and waist circumference (right eye: r = 0.456, p &lt; 0.000; left eye: r = 0.315, p &lt; 0.001). The PLD ratio can serve as a simple, non-invasive, and cost-effective autonomic function test.

Abstract 47: Deletion of PRR in AgRP Neurons of the Arcuate Nucleus Contributes to the Development of DOCA-Salt Hypertension

Agouti-related protein (AgRP) neurons, a key neuronal population within the arcuate nucleus (ARC), are known for their pivotal roles in regulating energy- and glucose homeostasis. However, their involvement in cardiovascular regulation remains poorly understood. Using RNAscope in situ hybridization, we found that 95.4% of the ARC AgRP neurons express the (pro)renin receptor (PRR), a component of the brain renin-angiotensin system that is crucial for blood pressure (BP) regulation. We therefore hypothesized that PRR signaling in the ARC AgRP neurons plays a regulatory role in the development of hypertension. To test this hypothesis, we selectively deleted PRR in ARC AgRP neurons by crossing AgRP-IRES-Cre mice with PRR fl/fl mice. Using RNAscope, as expected, AgRP Cre+ PRR fl/y mice displayed a significantly lower PRR mRNA in the ARC AgRP neurons than WT mice (76.3 ± 6.1 vs. 127.7 ± 2.9 AFU, p &lt; 0.05), indicating efficient ablation of PRR in ARC AgRP neurons. To examine the impact of PRR deletion in the ARC AgRP neurons on BP, the AgRP Cre+ PRR fl/y and control mice were implanted with telemetry probes to monitor BP continuously. After baseline recording, mice received DOCA-salt treatment (50 mg DOCA + saline as drinking water) for two weeks. BP variability and standard time domain heart rate variability (HRV) parameters, including overall HRV (SDNN) and short-term HRV (rMSSD), were analyzed from beat-to-beat intervals (n = 2-7 mice/group). At baseline, there was no difference between the two groups in BP, BP variability, and HRV. Two weeks of DOCA-salt induced a significantly higher BP in AgRP Cre+ PRR fl/y mice than the controls (156.2 ± 6 vs. 119.4 ± 3 mmHg, p &lt; 0.05), while BP variability did not differ between the two groups. Noteworthy, AgRP Cre+ PRR fl/y mice exhibited lower SDNN than the controls (13.3 ± 4 vs. 19.4 ± 4 ms), indicating increased sympathetic and/or reduced parasympathetic nervous activity. This lower SDNN suggests impaired cardiac autonomic function and adaptability to physiological demands in AgRP Cre+ PRR fl/y mice. Concurrently, AgRP Cre+ PRR fl/y mice showed a lower rMSSD (4.7 ± 0.5 vs. 10.8 ± 3.5 ms), implying reduced parasympathetic activity. In conclusion, deletion of PRR in the ARC AgRP neurons results in compromised cardiac autonomic function associated with the development of hypertension. Our findings underscore a novel protective role of PRR signaling in the ARC AgRP neurons in BP regulation.

Neuromodulation of Cardiovascular Risks Associated With Cardiotoxic Chemotherapy: A First-in-Human Randomized Pilot Study. Neuromodulation in Cancer Study (NCAN).

Cardiotoxic chemotherapy is used to treat malignancies such as breast cancer and lymphoma. These treatments predispose patients to cardiotoxicity that can lead to cancer treatment-related cardiac dysfunction (CTRCD). The use of high doses of anthracyclines or in combination with human epidermal growth factor receptor 2 antagonists is associated with a progressively higher risk of CTRCD. CTRCD is preceded by increased activation of the sympathetic nervous system and abnormal left ventricular mechanical deformation as measured by abnormal global longitudinal strain (GLS). Low-level tragus stimulation (LLTS) is a new, safe, noninvasive technique that offers great potential to reduce increased sympathetic activation and improve GLS. Here, we describe a study method to examine the effects of LLTS on autonomic balance and cardiac function in breast cancer or lymphoma patients treated with anthracyclines. A first-in-human pilot, randomized, double-blind feasibility study will evaluate 104 patients (age >50y) with breast cancer or lymphoma who receive anthracyclines with one additional CTRCD risk factor. Patients undergo 2 weeks of LLTS daily (1 h/d). Autonomic balance will be measured using heart rate variability metrics. Strain imaging using GLS will be performed pre and post-LLTS. Endothelial inflammation and oxidative stress measures will be performed using in vitro assays at baseline and after 2 weeks. We hypothesize that LLTS stabilizes sympathovagal imbalance and improves cardiac performance in anthracycline-treated patients with breast cancer or lymphoma.

Short-term exposure to indoor artificial light at night during sleep impairs cardiac autonomic function of young healthy adults in China

The artificial light at night (ALAN) exposure has emerged as a significant environmental and public health concern globally. However, there is far less evidence on the health effects of indoor ALAN than on outdoor ALAN. Moreover, evidence on cardiovascular effects of indoor ALAN is more limited. To evaluate the association between short-term exposure to ALAN during sleep with heart rate variability (HRV) in young healthy adults, as well as the mediating role of blood oxygen saturation (SpO2), and to further explore the intervention effects of shading habits, this prospective repeated measurement study was conducted among 81 adults with 150 nights (1324h) of HRV monitoring. HRV and SpO2 were monitored during sleep, concurrently with the measurement of indoor and outdoor ALAN. Shading habits were defined as whether to wear blindfolds or draw bed curtains during sleep, and were collected by questionnaires. Linear mixed-effect model was conducted to assess the association between ALAN exposure and HRV indices. The role of SpO2 in the association was analyzed using mediation analyses. We found that indoor ALAN exposure reduced parasympathetic activity and imbalanced cardiac autonomic function. We also found that the use of outdoor ALAN may underestimate or misestimate the potential health effects of ALAN. A significant mediation effects were observed on standard deviation of normal-to-normal intervals (SDNN; p-value for ACME = 0.014) and the ratio of low frequency power to high frequency power (LF/HF; p-value for ACME = 0.026) through minimum SpO2 after indoor ALAN exposure. The association between indoor ALAN and HRV was more pronounced among participants without shading habits during sleep. This study provides general population-based evidence that short-term exposure to indoor ALAN was significantly associated with impaired HRV, and SpO2 partially mediated the association. Improve shading habits during sleep may mitigate the adverse effects of indoor ALAN.

Brief Report: Baseline HRV Time Domain Parameters Predict Trauma and Depression Symptom Change in Veterans with PTSD Undergoing Biofeedback.

Heart rate variability (HRV) is an index of cardiac autonomic function and an objective biomarker for stress and health. Improving HRV through biofeedback has proven effective in reducing symptoms of posttraumatic stress disorder (PTSD) and depression in veteran populations. Brief protocols involving fewer sessions can better maximize limited clinic resources; however, there is a dearth of knowledge on the number of clinical sessions needed to significantly reduce trauma and depression symptoms. We conducted a series of linear regression models using baseline, post-intervention, and follow-up data from intervention group participants (N = 18) who engaged in a pilot waitlist-controlled study testing the efficacy of a 3-session mobile app-adapted HRV biofeedback intervention for veterans with PTSD. Based on Nunan et al. (Pacing and Clinical Electrophysiology 33:1407-1417, 2010) short-term norms, we found that pre-intervention RMSSD in the normal range significantly predicted PTSD and depression symptom improvement. Findings suggest the utility of baseline RMSSD as a useful metric for predicting HRV biofeedback treatment outcomes for veterans with PTSD and comorbid depression. Those with below-normal baseline RMSSD may likely need additional sessions or an alternative treatment to show clinically meaningful symptom improvement.

Compromised cardiac autonomic function in non-diabetic subjects with 1 h post-load hyperglycemia: a cross-sectional study

BackgroundA compromised cardiac autonomic function has been found in subjects with insulin resistance related disorders such as obesity, impaired glucose tolerance (IGT) and type 2 diabetes and confers an increased risk of adverse cardiovascular outcomes. Growing evidence indicate that 1 h plasma glucose levels (1hPG) during an oral glucose tolerance test (OGTT) ≥ 155 mg/dl identify amongst subjects with normal glucose tolerance (NGT) a new category of prediabetes (NGT 1 h-high), harboring an increased risk of cardiovascular organ damage. In this study we explored the relationship between 1 h post-load hyperglycemia and cardiac autonomic dysfunction.MethodsPresence of cardiac autonomic neuropathy (CAN) defined by cardiovascular autonomic reflex tests (CARTs) and heart rate variability (HRV), assessed by 24-h electrocardiography were evaluated in 88 non-diabetic subjects subdivided on the basis of OGTT data in: NGT with 1 h PG < 155 mg/dl (NGT 1 h-low), NGT 1 h-high and IGT.ResultsAs compared to subjects with NGT 1 h-low, those with NGT 1 h-high and IGT were more likely to have CARTs defined CAN and reduced values of the 24 h time domain HVR parameters including standard deviation of all normal heart cycles (SDNN), standard deviation of the average RR interval for each 5 min segment (SDANN), square root of the differences between adjacent RR intervals (RMSSD), percentage of beats with a consecutive RR interval difference > 50 ms (PNN50) and Triangular index. Univariate analyses showed that 1hPG, but not fasting and 2hPG, was inversely associated with all the explored HVR parameters and positively with CARTs determined presence of CAN. In multivariate regression analysis models including several confounders we found that 1hPG was an independent contributor of HRV and presence of CAN.ConclusionSubjects with 1hPG ≥ 155 mg/dl have an impaired cardiac autonomic function.