Successive RR Intervals Research Articles

Effects of six antipsychotic drug treatment regimens on short-term heart rate variability in patients with schizophrenia.

Many antipsychotic drugs have cardiac side effects due to their pharmacological actions. Heart rate variability (HRV) analysis can be used as a potential indicator of cardiotoxicity in cases where a decrease in HRV occurs after the administration of antipsychotics such as clozapine. The purpose of this study was to explore the effects of 6 antipsychotic drug regimens on short-term HRV in patients with schizophrenia. Data from 164 patients with schizophrenia between January 2018 and June 2023 were retrospectively analysed. Based on the drug used for treatment, the patients were categorised into clozapine combination (clozapine combined with aripiprazole, risperidone or ziprasidone), clozapine alone, olanzapine, aripiprazole, ziprasidone or risperidone groups. Heart rate variability indices were calculated using time domain analysis, including the standard deviation of the RR intervals (SDNN), the root mean square of successive RR interval differences (RMSSD) and the percentage of successive RR intervals over 50ms (PNN50). Compared with the pretreatment period, the SDNN, RMSSD and PNN50 were significantly lower in the clozapine combination, clozapine, olanzapine and aripiprazole groups at the end of weeks 2 and 4 of treatment (P < 0.05). However, these indicators in ziprasidone and risperidone groups did not show this significant decrease (P > 0.05). The effects of clozapine combination and clozapine on HRV were greater than for olanzapine, aripiprazole, ziprasidone or risperidone. Attention should be paid to controlling the dosage of clozapine combination and clozapine and monitoring the patient's electrocardiogram during administration.

Autonomic rehabilitation: Vagal and sympathetic impacts of modified occipitomastoid suture V-spread.

Autonomic rehabilitation using osteopathic manipulative treatment (OMT) to stimulate the vagus nerve may be a good adjunct therapy by physiatrists who treat dysautonomia. Heart rate variability (HRV) may provide quantitative evidence for the benefits of OMT on autonomic nervous system function. Elevated HRV indicates optimal health and reduced mortality risk, whereas low HRV is associated with stress, pain, and chronic disease pathology. To analyze the impact of modified occipitomastoid suture v-spread OMT technique on vagal tone by measuring HRV. Within-participant design with 5-minute HRV measurement pre- and post-OMT treatment. Clinical examination suites. Thirty healthy osteopathic medical students. A modified occipitomastoid suture v-spread treating somatic dysfunction by osteopathic physicians trained in osteopathic neuromusculoskeletal medicine. HRV variables related to vagal tone including root mean square of successive differences (RMSSD), percentage of successive normal sinus RR intervals >50 ms (pNN50), high frequency (HF), Parasympathetic Nervous System Index (PNSI), and Sympathetic Nervous System Index (SNSI). Repeated measures t-test analyzed the difference in mean HRV values after OMT. There were statistically significant increases in each of the HRV measures after OMT. Participants had a mean (95% confidence interval) RMSSD of 50.5 ms (38.3-62.8) at baseline and 55.0 ms (41.2-68.7, p = .013) post-OMT. pNN50 was 24.5% (17.6-31.3, n = 30) at baseline and 28.2% (20.8-35.6, p = .003) post-OMT. HF was 1549.6 ms2 (389.8-2709.4) at baseline and 1901.8 ms2 (618.2-3185.4, p = .103) post-OMT. PNSI was -0.1 (-0.5 to 0.2) at baseline and 0.1 (-0.3 to 1.5, p < .01) post-OMT, and SNSI was 0.2 (-0.1 to 0.6) at baseline and 0.05 (-0.3 to 0.4, p < .01) post-OMT. Normalization, due to high baseline variance, results include RMSSD 1.1 ms (1.0 to 1.1, p = .012), pNN50 1.3 (1.1 to 1.4, p = .011), and HF 1.2 ms2 (1.1 to 1.4, p = .018). Modified occipitomastoid suture v-spread may provide clinical benefit through increased vagal tone and decreased sympathetic activity.

Magnetic Garments Promote Parasympathetic Dominance and Improve Sleep Quality in Male Long-Distance Runners Following a 30 km Run

This study aimed to investigate the effects of high-intensity running on the autonomic nervous system and sleep quality of male long-distance runners and to examine the impact of wearing magnetic garments on these parameters. Fifteen highly trained male collegiate long-distance runners participated in a randomized, double-blind crossover study. Participants completed two 30 km runs (30k-RUN) during a 10-day training camp. After each run, they wore either magnetic (MAG) or non-magnetic control (CTRL) garments. Sleep quality and heart rate variability (HRV) were assessed using a wrist-worn device before and after each 30k-RUN. Wearing MAG garments post-30k-RUN resulted in significantly longer deep sleep duration compared to CTRL. HRV analysis revealed that the MAG condition led to a significantly higher root mean square of successive RR interval differences and high-frequency power, indicating enhanced parasympathetic activity. The low-frequency to high-frequency ratio was significantly lower in MAG than in CTRL. Perceived recovery scores were significantly higher in MAG than in CTRL. The findings of this study suggest that wearing magnetic garments following high-intensity endurance running may promote parasympathetic dominance and improve sleep quality in male long-distance runners. These findings indicate that magnetic garments may be a practical method for enhancing recovery in athletes following intense training.

Different implications of daytime and nighttime heart rate variability on total burden of cerebral small vascular disease in patients with nondisabling ischemic cerebrovascular events

ObjectiveThis study aimed to explore the relationship between total burden of cerebral small vessel disease (CSVD) and daytime and nighttime heart rate variability (HRV) parameters.MethodConsecutive patients with nondisabling ischemic cerebrovascular events were recruited from the cerebrovascular disease clinic of Changzhou Second People's Hospital between January 2022 and June 2023. A total of 144 enrolled participants were divided into a mild CSVD group (74 patients) and a moderate-to-severe CSVD group (70 patients) based on total burden of CSVD. Various HRV parameters measured during 24-h, 4-h daytime, and 4-h nighttime periods (including natural log–transformed [ln] root mean square of successive RR interval differences [RMSSD], ln absolute power of the high-frequency band [0.15–0.4 Hz] [HF], ln absolute power of the low-frequency band [0.04–0.15 Hz][LF], and LF-to-HF ratio [LF/HF]) were then assessed in the 2 groups. Spearman correlation analysis was used to assess the correlation between total burden of CSVD and HRV parameters. HRV parameters with P-value &amp;lt; 0.05 in correlation analysis were included in the multivariable logistic regression analysis, and restricted cubic spline analysis was performed to assess dose-response relationships.ResultsDaytime 4-h lnRMSSD (r = –0.221; P = 0.008) and 4-h lnHF (r = –0.232; P = 0.005) were negatively correlated with total burden of CSVD, and daytime 4-h lnLF/HF (r = 0.187; P = 0.025) was positively correlated with total burden of CSVD. There was no correlation between nighttime HRV parameters and total burden of CSVD. After adjustments were made for potential confounders, daytime 4-h lnRMSSD (OR = 0.34; 95% CI: 0.16–0.76), 4-h lnHF (OR = 0.57; 95% CI: 0.39–0.84), and 4-h lnLF/HF (OR = 2.12; 95% CI: 1.18–3.82) were independent predictors of total burden of CSVD (all P &amp;lt; 0.05). S-shaped linear associations with moderate-to-severe total burden of CSVD were seen for daytime 4h-lnRMSSD (P for nonlinearity = 0.543), 4-h lnHF (P for nonlinearity = 0.31), and 4-h lnLF/HF (P for nonlinearity = 0.502).ConclusionDaytime parasympathetic HRV parameters are independent influencing factors of total burden of CSVD and may serve as potential therapeutic observation indicators for CSVD.

Improvement of heart rate variability after metabolic bariatric surgery in Korean subjects with obesity.

Cardiovascular autonomic neuropathy (CAN) is a chronic complication of diabetes. As obesity is a major risk factor for CAN, we hypothesized that metabolic bariatric surgery (MBS) could improve CAN indices in Korean patients with obesity. Patients who underwent bariatric surgery between February 2020 and June 2022 were prospectively recruited. CAN was conducted once before surgery and again after surgery, using the Ewing method and heart rate variability (HRV) analysis (standard deviation of the NN interval [SDNN], root mean square of successive RR interval difference [RMSSD], and spectral analysis). A total of 47 patients were included. The mean age was 39.8 ± 8.7 years, 15 (31.9%) were male, and 26 (55.3%) had diabetes. Resting HR before surgery was 81.0 ± 12.3 bpm, which decreased significantly to 68.0 ± 9.3 bpm after surgery (P < 0.001). Changes in HR and BP according to the Valsalva maneuver, postural changes, and handgrip were not significantly different before and after surgery. However, SDNN significantly increased from 25.2 [15.1, 33.5] to 38.0 [25.4, 45.0] ms (P < 0.001), and RMSSD also significantly increased from 17.0 [9.2, 31.8] to 28.2 [15.3, 45.6] ms (P = 0.001). Both low-frequency power (LF) and high-frequency power (HF) increased significantly, and the LF/HF ratio significantly decreased from 2.1 ± 1.6 to 1.3 ± 1.3 (P = 0.010). Loss of weight, fat mass, and lean body mass were independently associated with improving the HRV variables. MBS improved HRV variables, and these changes were mainly associated with postoperative weight loss.

Postpartum Blood Pressure Variability and Heart Rate Variability in Preeclampsia.

Preeclampsia is associated with autonomic dysregulation during pregnancy; however, less is known about autonomic function in the first week postpartum after preeclampsia. We retrospectively analyzed data from a prospective cohort of women with and without preeclampsia. Continuous blood pressure and heart rate were measured with finger plethysmography within 7 days postpartum. Frequency-domain blood pressure and heart rate variability (HRV) were calculated using spectral analysis. Time-domain HRV was calculated as the root mean square of successive RR interval differences. We compared results between those with and without preeclampsia, as well as between those with new-onset preeclampsia, chronic hypertension with superimposed preeclampsia, and normotensive participants. A total of 70 postpartum women were enrolled: 20 normotensive, 29 new-onset preeclampsia, and 21 superimposed preeclampsia. Both low- and high-frequency blood pressure variabilities were higher in those with preeclampsia compared with controls (P=0.04 and P=0.02, respectively). This difference was driven by those with new-onset preeclampsia. The preeclampsia group had lower high-frequency HRV (P<0.005), a higher low-/high-frequency ratio of HRV (P<0.005), and lower time-domain HRV (P=0.01); this difference was seen in those with and without chronic hypertension. Postpartum patients with preeclampsia with and without chronic hypertension had lower HRV compared with normotensive postpartum controls. Higher blood pressure variability was observed only in those with nonsuperimposed preeclampsia, suggesting that the autonomic profile of preeclampsia may differ in patients with chronic hypertension.

Do extra-pulmonary triggers or autonomic neural activity affect rhythm control by anti-arrhythmic drugs in patients with post-ablation atrial fibrillation recurrence?

The role of anti-arrhythmic drugs (AADs) in recurrent atrial fibrillation (AF) after catheter ablation (CA) is not fully understood. The aim of this study was to explore the effects of AADs in patients who recurred after AFCA depending on extra-pulmonary vein triggers (ExPVTs) and post-ablation heart rate variability (HRV) parameters. We analyzed 2,036 patients who underwent de-novo AFCA and 486 patients with post-AFCA recurrence who underwent rhythm control with AADs. We investigated the effects of ExPVTs and 3rd month HRV parameters on the post-AFCA recurrence and subsequent AAD responsiveness. A total of 486 out of 2,036 patients developed clinical recurrence of AF and subsequently underwent rhythm control with AADs. 486 out of 310 patients (63.8%) remained free of second recurrence at 1-year. Post-AFCA recurrence was significantly higher in patients with ExPVT [Log-rank p < 0.001, HR 1.45 (1.16-1.83), p = 0.001] or higher 3rd month root mean square of the differences between successive RR intervals (rMSSD) [Log-rank p < 0.001, HR 1.36 (1.11-1.65), p = 0.003] than their counterparts. Patients with ExPVTs during the de-novo procedure had significantly higher 3rd month rMSSD (15.0 [11.0-23.0] vs. 17.0 [11.0-28.0], p = 0.022). Patients with high 3rd month rMSSD had higher rate of ExPVTs during the repeat procedure (n = 160, 41.0% vs. 22.2%, p = 0.019). Among patients with recurrent AF after AFCA, post-AAD recurrence did not differ depending on the presence of ExPVT [Log-rank p = 0.455, HR 1.12 (0.78-1.69), p = 0.436] or 3rd month rMSSD [Log-rank p = 0.457, HR 1.16 (0.87-1.55), p = 0.300]. Post-AAD recurrence did not differ between class IC and III AADs (p for interaction = 0.311). ExPVT and post-procedural high rMSSD are independent risk factors for post-AFCA recurrence but not for AAD response in patients with recurrent AF. AADs may suppress ExPVTs and modulate cardiac autonomic activity after post-AFCA recurrence.

A Bayesian analysis of heart rate variability changes over acute episodes of bipolar disorder

Bipolar disorder (BD) involves autonomic nervous system dysfunction, detectable through heart rate variability (HRV). HRV is a promising biomarker, but its dynamics during acute mania or depression episodes are poorly understood. Using a Bayesian approach, we developed a probabilistic model of HRV changes in BD, measured by the natural logarithm of the Root Mean Square of Successive RR interval Differences (lnRMSSD). Patients were assessed three to four times from episode onset to euthymia. Unlike previous studies, which used only two assessments, our model allowed for more accurate tracking of changes. Results showed strong evidence for a positive lnRMSSD change during symptom resolution (95.175% probability of positive direction), though the sample size limited the precision of this effect (95% Highest Density Interval [−0.0366, 0.4706], with a Region of Practical Equivalence: [-0.05; 0.05]). Episode polarity did not significantly influence lnRMSSD changes.

Impact of slouching on heart rate variability and cardiovascular health among medical students

Background: Medical students frequently adopt poor postures such as slouching potentially impacting health. Heart rate variability (HRV) serves as an indicator of autonomic nervous system function, correlated with cardiovascular health. Aims and Objectives: The objective of the study was to compare HRV parameters among medical students in three postures: Sitting erect, easy pose (cross-legged), and slouching (stooping head and shoulders). Materials and Methods: A comparative cross-sectional study enrolled 26 male medical students. Participants were instructed to maintain each posture for 5 min while HRV was recorded using a Polar V800. Time domain and frequency domain parameters among different postures were analyzed using Friedman’s test and post hoc tests for pairwise comparisons. P&lt;0.05 was considered significant. Data were expressed as median interquartile range. Results: Significant differences were observed in HRV parameters between postures. The easy pose demonstrated a significantly higher median value of root mean square of differences of successive RR intervals (48.28 ms vs. 35.35 ms) and pNN50% (24.40% vs. 13.62%) compared to slouching. Frequency domain analysis revealed a significantly higher median value of high-frequency (HF) power in easy pose (626.56 ms² vs. 378.15 ms²) and HF normalized unit (33.78 vs. 22.55) compared to slouching. A lower low frequency (LF)/HF ratio and (1.96 vs. 3.43) lower LF normalized unit (66.18 vs. 77.30) was also seen in easy pose. Although statistically not significant, the parasympathetic indicators of HRV were higher in erect sitting compared to slouching posture. Conclusion: Among medical students, adopting the easy pose (cross-legged sitting) appeared to enhance HRV and thus increase parasympathetic activity, whereas adopting slouching postures decreased it.

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&lt;0.05 was considered statistical significance. Results: Significantly higher mean HR (Heart rate) (p&lt;0.01) and significantly lower mean RR (Normal to normal QRS complex) interval,CVRR (Coefficient variation of RR interval) (p&lt;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 &gt;50 ms) (p&lt;0.001)were observed in PD patients compared to control. In PD patients, significantly lower (p&lt;0.001) serum Zn and significantly higher (p&lt;0.01) serum Mg were observed compared to control. In addition,significant decrement was observed in SDRR, CVRR (p&lt;0.05), SDSD, RMSSD, and pRR50% (p&lt;0.01) in hypozincemic PD patients compared to normozincemic patients. On correlation analysis, significant positive correlations of serum Zn were observed with SDRR (p&lt;0.05),SDSD (p&lt;0.001), RMSSD (p&lt;0.001) and pRR50% (p&lt;0.01). Moreover,serum Mg was positively correlated with SDRR (p&lt;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

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 &gt;50 ms (pRR50%) were significantly lower (p&lt;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&lt;0.01, p&lt;0.001,p&lt;0.01) RMSSD(p&lt;0.01, p&lt;0.001, p&lt;0.01), pRR50%(p&lt;0.01, p&lt;0.01, p&lt;0.05)and serum Ca was also positively correlated with SDRR(p&lt;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

An exploratory investigation of heart rate and heart rate variability responses to daylong heat exposure in young and older adults.

Heart rate variability (HRV) has shown potential as a tool for monitoring thermal strain, but there is limited data to support its efficacy in older adults during prolonged heat exposures. We compared HRV between young (19-31 years, n=20) and older (61-78 years, n=39) adults during 9 hours of heat exposure (40°C, 9% RH). We also explored whether heart rate (HR) and/or HRV could be used to distinguish older adults who achieved elevated thermal strain, defined as either 1) an increase in core temperature >1.0°C (occurring in 39% [15/39]) or 2) a reduction in systolic blood pressure >10 mm Hg (occurring in 67% [26/39]). Percentage of age-predicted maximal HR and percentage of heart rate reserve (HRR) were higher, whereas standard deviation of normal RR intervals (SDNN), the square root of the mean of squared differences between successive RR intervals (RMSSD), high frequency power (HF), and cardiac vagal index (CVI) were lower in older compared to young adults (P≤0.004) during heat exposure. In older adults, increases in core temperature were correlated with percentage of age-predicted maximal HR, percentage of HRR, RMSSD, and CVI (P≤0.031), whereas changes in systolic blood pressure were not significantly associated with HR or HRV indices (P≤0.327). Receiver operating characteristic curve analysis indicated that HR and HRV indices had generally poor ability to identify older adults with elevated thermal strain (area under the curve ≤0.65). Age-related differences in HRV, consistent with vagal withdrawal among older adults, remained during daylong heat exposure, but marked heterogeneity of response likely contributed to HRV providing limited discriminatory value in identifying changes in core temperature or blood pressure in older adults.

A Comparative Analysis of Heart Rate Variability Indices in Patients with Liver Cirrhosis.

Cardiac autonomic dysfunction (AD) in reference to chronic liver disease (CLD) has become widely accepted as a symptomatic burden. This study will be undertaken to measure heart rate variability (HRV) indices and detect the severity of cardiac autonomic dysfunction in CLD patients. This study was conducted on 150 patients with liver cirrhosis and compared with 110 healthy controls. Information concerning medical history, radiological and laboratory findings was extracted for interpretation and association among both groups. The HRV was assessed by recording with a polygraph (RMS Polyrite D, version 1.0), which was based on the principle of electrocardiography. Heart rate variability indices like standard deviation of each interval normal-to-normal (SDNN), percentage of successive RR intervals that differ by >50 ms (pNN50%), high frequency (HF), low frequency (LF), and the LF/HF ratio were found to be remarkably low in cases with CLD in comparison to the healthy control group (p < 0.05). The Child-Pugh (CP) score was class C (10-15) in 52%, class B (7-9) in 30%, and class A (5-6) in 18% of patients. The CP score in CLD patients had a statistically significant negative correlation with SDNN (r = -0.5429, p < 0.001), root mean square of successive differences (RMSSD) (r = -0.375, p < 0.001), pNN50% (r = -0.6037, p < 0.001), HF (r = -0.2033, p = 0.0125), and LF (r = -0.3674, p < 0.001). SDNN, pNN50%, and LF parameters were lowest in alcohol-related CLD, highest in hepatitis C virus (HCV)-related CLD, and intermediate in hepatitis B virus (HBV)-related CLD. Our study concluded that liver cirrhosis patients have reduced HRV compared to healthy individuals. A decrease in HRV highlights people at risk of death. This is a variable that can be used to track patients over time and aid in transplant selection.

Recovery of heart rate and heartrate variability after a maximal cardiopulmonary exercise test in novice female runners.

Previous studies have shown delayed cardiac vagal reactivation after high-intensity endurance exercise when estimated with heartrate variability (HRV). However, the recovery dynamics of RR intervals (RRI) and HRV after a maximal incremental exercise test have been studied less in non-athletic population and especially in females. The main aim of the study was to examine the recovery dynamics of RRI and HRV immediately after a maximal cardiopulmonary exercise test (CPET) in adult females. Twenty-eight healthy, novice recreational female runners (33.7 ± 4.2years) were selected to participate in this study from a larger group of participants (Run RCT). RRIs were collected continuously during a controlled rest, a CPET on a treadmill and a 15-min controlled, passive recovery. Minute-by-minute recovery dynamics were analyzed. The dynamic phase of RRI and heart rate recovery (HRR) (from 192.2 ± 9.9 to 111.4 ± 2.4, P < 0.001) occurred during the first 4.5min with HRR of 36 ± 10 beats during the first minute of the recovery. Resting heart rate was negatively associated (r = - 0.53, P = 0.016) with HRR during the recovery. No recovery of root mean square of successive RRIs (RMSSD) was detected during the 15-min recovery. RMSSD was 15.0 ± 9.2% of resting values at the end of the recovery. No recovery of vagal-derived HRV was detected immediately after a CPET in novice recreational female runners despite marked changes in sympathovagal balance, detected by rapid recovery of RRI during the first 5min after exercise cessation.

Cardiac electrophysiology, structure and diastolic function in patients with diabetic foot versus those without diabetic foot.

To evaluate the differences in cardiac autonomic function, cardiac structure and diastolic function between individuals with diabetic foot (DF) and those with diabetes but without DF. A total of 413 individuals with DF and 437 without DF who underwent a 24-h electrocardiogram Holter and a Doppler echocardiogram were included. The heart rate variability parameters to evaluate cardiac autonomic function, and the indices for the assessment of cardiac structure and left ventricular (LV) diastolic function, including left atrium, LV posterior wall thickness, interventricular septum and E/e' ratio, were measured or calculated. Propensity score matching was used for the sensitivity analysis to minimize potential imbalance. In both the crude and propensity score matching analyses, significant differences were observed in heart rate variability between individuals with and without DF, as evidenced by lower standard deviation of the normal sinus interval, lower low-frequency power/high-frequency power ratio, lower standard deviation of the 5-min average RR intervals, lower low-frequency power, lower percentage of normal adjacent RR interval difference >50 ms, lower root mean square of successive RR interval differences and lower high-frequency power (all P < 0.05). In multivariate analysis, DF showed an independent negative correlation with the aforementioned indices of heart rate variability (all P < 0.05). Individuals with DF showed higher left atrium, LV posterior wall thickness, interventricular septum and a higher E/e' ratio than those without DF in the crude analysis (all P < 0.05), whereas these indices were no longer associated with DF in the multivariate analysis and the propensity score matching analyses. Cardiac autonomic modulation was more severely impaired in individuals with DF than in their counterparts without DF. There has been insufficient evidence to demonstrate the independent association of DF and LV diastolic dysfunction.

Comparison of Heart Rate Variability in Thai Older Adults with Hypertension, Pre-Hypertension, and Normotension.

This study aims to compare HRV variables across three cohorts: normotensive (NT), prehypertensive (pre-HT), and hypertensive (HT) and to assess the relationship between the blood pressure (BP) and HRV parameters. Employing a cross-sectional design, 64 older participants were categorized based on the Joint National Committee's criteria into NT (n = 10), pre-HT (n = 33), and HT (n = 21) groups. Anthropometric data, lipid profiles, and HRV indices were evaluated. HRV data were obtained from the Polar V800 chest strap device using HRV Kubios software for data analysis of short-term recordings lasting 10 minutes. This analysis encompasses both time and frequency domain assessments. The time domain includes the standard deviation of NN intervals (SDNN), the root mean square of successive RR interval differences (RMSSD), and the percentage of successive RR intervals differing by over 50 ms (pNN50). The frequency domain includes low frequency (LF), high frequency (HF), and the ratio of LF-to-HF power (LF/HF). Data were statistically analyzed via one-way analysis of variance (ANOVA) and Pearson correlation. The HT group exhibited significantly lower values in SDNN, pNN50, LF power, and HF power in comparison to the NT group (P < 0.05). Moreover, the HT group had a significantly lower SDNN value compared to the pre-HT group (P < 0.05). Inverse associations were uncovered between systolic and diastolic blood pressure and SDNN, pNN50, and HF power (P < 0.05). Multiple regression further highlighted the significance of systolic and pulse pressure concerning HF power (P < 0.05). HRV indices are reduced in Thai older adults with HT compared with those with NT. Monitoring HRV in older adults can provide valuable insights into autonomic function and cardiovascular disease risk.

Diving into old age: exercise and aging affect cardiovascular control in a long-lived mammal, the Weddell seal

The central component of the mammalian dive response is bradycardia, which, in combination with other physiological mechanisms, conserves intrinsic oxygen stores and facilitates longer submersion. Several factors are hypothesized to affect diving heart rate ( fH) and its variability (HRV) through a shift in autonomic balance. This study aimed to elucidate how dive duration, aging, and exercise influence fH and HRV (calculated as root mean square of successive RR interval differences) of free-ranging Weddell seals ( Leptonychotes weddellii). We expected that mean dive fH and HRV would differ with dive duration, advancing age, and exercise intensity due to a shift in autonomic balance. We collected ECG data from free-ranging female Weddell seals in Erebus Bay, Antarctica (n=10 seals, n=120 dives, age range 9-25 years old). To increase the cost of transport, we affxed a “drag block” to three seals for a portion of their deployment period (n=30 dives). Linear mixed effects model selection identified the effects of dive behavior (duration and depth), seal age, and drag block presence on mean dive fH and HRV. As dive duration increased, mean dive fH decreased (F1,107=227.91, p&lt;0.0001) while HRV increased (F1,103=84.47, p&lt;0.0001), suggesting increased parasympathetic tone. HRV was reduced in older seals (F1,8=8.73, p=0.018), indicating attenuation of parasympathetic influence on bradycardia with advancing age. Consistent with this interpretation, HRV increased with dive duration more steeply in younger animals (age*duration: F1,103=10.31, p=0.002). When exercise effort was experimentally modified by attaching a drag block to free-ranging seals, both mean dive fH (F1,107=6.07, p=0.015) and HRV (F1,103=4.34, p=0.039) were affected; dive HRV was significantly higher when seals dove with a drag block. However, this result should be interpreted with caution until the effects of swimming effort on fH and HRV can be determined. There was a significant interaction between animal age and factors affecting cardiovascular control (age*drag: F1,107=5.16, p=0.028); mean dive fH increased with age when seals did not carry a drag block, but decreased with age when a drag block was present. Taken together, our results point to cardiovascular aging as a physiological element that could affect the foraging ability, fitness, and life history of a long-lived free-ranging mammal. Funding by the National Science Foundation (#0649609, #0440715, #2020706). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Circadian changes of autonomic function in patients with zoster-associated pain: A heart rate variability analysis.

To investigate the circadian changes of the autonomic function in patients with zoster-associated pain (ZAP). A total of 37 patients with ZAP from April 2022 to October 2022 were enrolled as the observation group, and 37 normal volunteers at the same time were selected as the control group. All participants were required to wear a 24-h Holter, which was used to compare the heart rate variability (HRV) between the two groups. HRV analysis involved time- and frequency-domain parameters. There was no statistically significant difference in general information between two groups. Patients with ZAP had an increased mean heart rate and decreased the standard deviation of normal-to-normal (SDNN) R-R interval, the root mean square of the differences (RMSSD) in successive RR interval, low frequency (LF), and high frequency (HF) compared with control groups in all periods (p<.05). The ratio of LF/HF between two groups had no significant difference (p=.245). SDNN had no significant difference between day and night in the control group (p>.05), whereas SDNN of ZAP patients in night period was reduced than that in day period (p<.001). The level of RMSSD during the day was lower than those at night in the control group (p<.05), whereas no significant difference of RMSSD between two periods was observed in patients with ZAP (p>.05). The results of this study indicated that ZAP contributes to the decline of autonomic nervous system (ANS) function, especially parasympathetic components. The patients with ZAP lost parasympathetic advantage and had a worse ANS during the night.

Continuous Long-Term Assessment of Heart Rate Variability in Adults with Cyanotic Congenital Heart Disease after Surgical Repair.

Background: Heart rate variability (HRV) is an established, non-invasive parameter for the assessment of cardiac autonomic nervous activity and the health status in general cardiology. However, there are few studies on HRV in adults with congenital heart defects (CHDs). The aim of the present study was to evaluate the use of long-term continuous HRV measurement for the assessment of global health status in adults with cyanotic CHD. Methods: This prospective study included 45 adults (40% female, mean age = 35.2 ± 9.2 [range: 19-58] years) after cardiac surgical repair. HRV parameters were calculated from continuous 24 h measurements using a Bittium Faros 180 sensor (Bittium Corp., Oulu, Finland). Results: Postoperative patients with transposition of the great arteries (TGA) (n = 18) achieved significantly higher values of standard deviation of NN intervals (SDNN) (175.4 ± 59.9 ms vs. 133.5 ± 40.6 ms; p = 0.013) compared with patients with other conotruncal anomalies (n = 22). Comparing patients with TGA after a Senning-Brom or Mustard operation (n = 13) with all other heart surgery patients (n = 32), significantly higher HRV parameters were found after atrial switch (root mean square of successive RR interval differences: 53.6 ± 20.7 ms vs. 38.4 ± 18.3 ms; p = 0.019; SDNN: 183.5 ± 58.4 ms vs. 136.3 ± 45.3 ms; p = 0.006). A higher SDNN was also measured after Senning-Brom or Mustard operations than after a Rastelli operations (n = 2) (SDNN: 183.5 ± 58.4 ms vs. 84.5 ± 5.2 ms; p = 0.037). When comparing atrial switch operations (n = 3) with Rastelli operations, the SDNN value was significantly shorter in the Rastelli group (p = 0.004). Conclusions: Our results suggest that continuous HRV monitoring may serve as a marker of cardiac autonomic dysfunction in adults with cyanotic CHD after surgical repair. Impaired cardiac autonomic nervous activity may be associated with an increased risk of adverse reactions in patients with repaired CHD. Therefore, a longitudinal assessment of HRV patterns and trends may provide a deeper insight into dynamic changes in their autonomic regulation and disease progression, lifestyle changes, or treatments. As each person has individual variability in heart rate, HRV may be useful in assessing intra-individual disease progression and may help to improve personalized medicine. Further studies are needed to better understand the underlying mechanisms and to explore the full potential of HRV analysis to optimize medical care for ACHDs.

PRR30, pRR3.25% and Asymmetrical Entropy Descriptors in Atrial Fibrillation Detection.

Early detection of atrial fibrillation (AF) is essential to prevent stroke and other cardiac and embolic complications. We compared the diagnostic properties for AF detection of the percentage of successive RR interval differences greater than or equal to 30 ms or 3.25% of the previous RR interval (pRR30 and pRR3.25%, respectively), and asymmetric entropy descriptors of RR intervals. Previously, both pRR30 and pRR3.25% outperformed many other heart rate variability (HRV) parameters in distinguishing AF from sinus rhythm (SR) in 60 s electrocardiograms (ECGs). The 60 s segments with RR intervals were extracted from the publicly available Physionet Long-Term Atrial Fibrillation Database (84 recording, 24 h Holter ECG). There were 31,753 60 s segments of AF and 32,073 60 s segments of SR. The diagnostic properties of all parameters were analysed with receiver operator curve analysis, a confusion matrix and logistic regression. The best model with pRR30, pRR3.25% and total entropic features (H) had the largest area under the curve (AUC)-0.98 compared to 0.959 for pRR30-and 0.972 for pRR3.25%. However, the differences in AUC between pRR30 and pRR3.25% alone and the combined model were negligible from a practical point of view. Moreover, combining pRR30 and pRR3.25% with H significantly increased the number of false-negative cases by more than threefold. Asymmetric entropy has some potential in differentiating AF from SR in the 60 s RR interval time series, but the addition of these parameters does not seem to make a relevant difference compared to pRR30 and especially pRR3.25%.