Diurnal variation of cardiac autonomic activity in adolescent non-suicidal self-injury

Heart rate (HR) and vagally mediated heart rate variability (HRV) are two distinct biomarkers of cardiac autonomic activity. Decreased cardiac vagal activity (or decreased HRV) in particular has been linked with impairments in the functional flexibility of the central autonomic network (CAN), resulting in impaired stress and emotion regulatory capacities. Decreased HRV is widely used as trait marker of psychopathology. Repetitive engagement in non-suicidal self-injury (NSSI) in adolescence correlates with both deficits in stress and emotion regulation, as well as decreased HRV. Existing research has, however, focused on short-term recordings of HR and HRV under resting and phasic conditions. In this study, we examined whether diurnal variation of cardiac autonomic activity, indexed by cosinor parameters of HR and HRV derived from 48 h of ambulatory ECG recording under natural conditions over a weekend, are altered in female adolescents with NSSI disorder compared to controls (HC; N = 30 per study group). Several important confounds, including physical activity, were controlled for. Female adolescents with NSSI show higher rhythm-adjusted 24 h mean levels and greater respective amplitude of HR, as well as lower rhythm-adjusted 24 h mean levels and smaller respective amplitude of HRV. Peak levels in both HR and HRV in the NSSI group were reached approximately 1 h later compared to HC. Severity of exposure to early life maltreatment might be linked with altered amplitudes of 24 h HR and HRV. Diurnal rhythms of cardiac autonomic activity might hold promise as objective indicators of disordered stress and emotion regulation in developmental psychopathology, and as such should be investigated in future studies with rigorous assessment and control of potential confounds.

Cardiac deceleration capacity is associated with severity of inflammation in COVID-19

PURPOSE

In this pilot study, we investigated the cardiac autonomic activity of coronavirus disease 2019 (COVID-19)-infected hospitalized patients. COVID-19 is characterized by cough, fever, and dyspnea, which in some severe cases can lead to hypoxia, respiratory failure, and shock. Since breathing disorders and pulmonary diseases are tightly linked to autonomic dysfunction, we analyzed the cardiac autonomic activity by measuring the deceleration capacity (DC) in COVID-19 patients.

METHODS

In 14 adults (4 men and 10 women) with a median age of 63.5 years and positive for SARS-CoV-2 by polymerase chain reaction (PCR) with severe symptoms requiring hospital treatment, a high-resolution digital 30 min electrocardiogram (ECG) in Frank leads configuration was performed in a resting supine position within the first 48 h after hospital admission. DC was assessed using validated software and associated with several markers of inflammation and clinical course.

RESULTS

The study revealed a significant association between reduced DC (≤ 2.5 ms) and older age (74 years) in COVID-19 patients, compared to those with a higher DC > 2.5 ms (56.5 years). However, the duration of hospitalization was similar for both groups. There was a nonsignificant trend towards a higher maximum viral load in patients with reduced DC. Further, patients with a DC ≤ 2.5 ms showed higher levels of inflammatory markers such as C-reactive protein (CRP) and procalcitonin (PCT), as well as leukocytosis, compared to patients with a DC > 2.5 ms. Also, the COVID-19-severity marker ferritin was significantly elevated in patients with lower DC. Other markers associated with COVID-19, such as lactate dehydrogenase (LDH) and creatine kinase (CK), exhibited comparable levels in both groups.

CONCLUSIONS

Reduced DC (≤ 2.5 ms) was significantly associated with older age, increased inflammatory markers, and elevated ferritin in patients with COVID-19. These findings suggest that DC might serve as a valuable indicator for predicting the risk of severe inflammation in COVID-19 and possibly complications associated with this disease, such as heart failure. Further studies are needed to confirm these observations and clarify the clinical significance of DC in COVID-19 and other infectious diseases.

Effectiveness of sleep surgery versus a mandibular advancement device for obstructive sleep apnea in terms of nocturnal cardiac autonomic activity

PURPOSE

Sleep surgery and mandibular advancement devices (MAD) are treatments for obstructive sleep apnea (OSA), but their comparative efficacy remains unclear. We compared their efficacy using various parameters.

METHODS

Subjects treated for OSA with sleep surgery or MAD (n = 30/group)-matched for sex, body mass index (BMI), and baseline apnea-hypopnea index (AHI)-were enrolled. The efficacy of these treatments according to polysomnographic parameters, sleep quality questionnaires, and heart rate variability (HRV) time- and frequency-domain parameters were compared between pre-treatment and 3-month post-treatment.

RESULTS

Polysomnographic and sleep quality questionnaire parameters improved significantly in both groups. In time-domain HRV analysis, average normal-to-normal intervals increased significantly in the surgery (942.2 ± 140.8 to 994.6 ± 143.1, P = 0.008) and MAD (901.1 ± 131.7 to 953.7 ± 123.1, P = 0.002) groups. Low frequency (LF) decreased significantly in the surgery group (P = 0.012); high frequency (HF) remained unchanged in both groups. The LF/HF ratio decreased in both groups (2.9 ± 1.8 to 2.3 ± 1.7, P = 0.017, vs. 3.0 ± 1.8 to 2.4 ± 1.4, P = 0.025). Normalized high frequency increased significantly in both groups (31.0 ± 13.2 to 36.8 ± 13.7, P = 0.009, vs. 29.1 ± 10.7 to 33.7 ± 12.5, P = 0.024), in contrast to normalized low frequency. However, no HRV parameter changes differed significantly between the groups after adjusting for age, BMI, and AHI.

CONCLUSION

Sleep surgery and MAD are equally effective treatments for OSA according to cardiac autonomic activity.

Analysis of Heart Rate Variability in a Patient with Takotsubo Cardiomyopathy Syndrome on the Actual Onset Day

A healthy 73-year-old woman unpredictably developed Takotsubo cardiomyopathy syndrome (TTS) during Holter-electrocardiogram (ECG) recording. Thus, the complete chronological ECG data on the actual onset day of TTS were obtained. Many heart rate variability (HRV) parameters, including the low-frequency components (LF) and the high-frequency components (HF), on the actual onset day and in the healing phase were calculated. The interesting facts on the actual onset day were that the suppression of both LF and HF appeared earlier than the changes of the ECG waveform; and the LF/HF ratio remained within the normal range, although both LF and HF were markedly suppressed. The abnormality on the actual onset day was clear compared with the healing phase. It is noteworthy to obtain the chronological ECG data on the actual onset day of TTS in a healthy patient. The present data are unique in terms of being analyzed on the actual onset day. Although the HRV parameters, including LF and HF, were obviously abnormal, there is some skepticism about using HRV parameters as indices of cardiac autonomic activity. In the present case, it was concluded that the abnormality of cardiac autonomic activity contributed to the onset of TTS. These data are unlikely to ever be replicated, and we hope that this report helps elucidate the TTS mechanism.

Delayed parasympathetic reactivation and sympathetic withdrawal following maximal cardiopulmonary exercise testing (CPET) in hypoxia

PURPOSE

This study investigated the effects of acute hypoxic exposure on post-exercise cardiac autonomic modulation following maximal cardiopulmonary exercise testing (CPET).

METHODS

Thirteen healthy men performed CPET and recovery in normoxia (N) and normobaric hypoxia (H) (FiO₂ = 13.4%, ≈ 3500 m). Post-exercise cardiac autonomic modulation was assessed during recovery (300 s) through the analysis of fast-phase and slow-phase heart rate recovery (HRR) and heart rate variability (HRV) indices.

RESULTS

Both short-term, T30 (mean difference (MD) 60.0 s, 95% CI 18.2-101.8, p = 0.009, ES 1.01), and long-term, HRRt (MD 21.7 s, 95% CI 4.1-39.3, p = 0.020, ES 0.64), time constants of HRR were higher in H. Fast-phase (30 and 60 s) and slow-phase (300 s) HRR indices were reduced in H either when expressed in bpm or in percentage of HR_peak (p < 0.05). Chronotropic reserve recovery was lower in H than in N at 30 s (MD - 3.77%, 95% CI - 7.06 to - 0.49, p = 0.028, ES - 0.80) and at 60 s (MD - 7.23%, 95% CI - 11.45 to - 3.01, p = 0.003, ES - 0.81), but not at 300 s (p = 0.436). Concurrently, Ln-RMSSD was reduced in H at 60 and 90 s (p < 0.01) but not at other time points during recovery (p > 0.05).

CONCLUSIONS

Affected fast-phase, slow-phase HRR and HRV indices suggested delayed parasympathetic reactivation and sympathetic withdrawal after maximal exercise in hypoxia. However, a similar cardiac autonomic recovery was re-established within 5 min after exercise cessation. These findings have several implications in cardiac autonomic recovery interpretation and in HR assessment in response to high-intensity hypoxic exercise.

Yoga Offers Cardiovascular Protection in Early Postmenopausal Women

CONTEXT

Postmenopause, an estrogen deficient state comes with increased incidence of cardiovascular diseases (CVDs). Yoga has been described as having a beneficial effect on heart rate variability (HRV), a marker for cardiac autonomic activity which can assess cardiovascular risk, in various populations.

AIM

the aim of the study was to study the effect of 3-month long Yoga practice on HRV in early postmenopausal women.

SETTINGS AND DESIGN

A prospective longitudinal study of 67 women within 5 years of menopause between 45 and 60 years of age attending menopause clinic of Department of Gynaecology, Sucheta Kriplani Hospital fulfilling inclusion and exclusion criteria and consenting were enrolled for the study.

SUBJECTS AND METHODS

HRV of 37 cases (Yoga group) and 30 controls (non-Yoga group) was recorded pre and 3-month postintervention.

STATISTICAL ANALYSIS USED

GraphPad Prism Version 5 software was used. Values are a mean and standard error of mean. Statistical significance was set up at P < 0.05.

RESULTS

In HRV, frequency domain analysis showed a significant fall in low frequency (LF) in normalized units (nu) and LF: high frequency (HF) ratio and significant rise in HF in nu in the Yoga group (depicting parasympathetic dominance) against a significant rise in LF (nu) and LF: HF ratio and significant fall in HF (nu) in non-Yoga group (indicating sympathetic dominance). Time domain analysis showed a significant decrease in Standard Deviation of NN intervals in Non-Yoga group against nonsignificant changes in Yoga group indicating deterioration in parasympathetic activity in non-Yoga group.

CONCLUSIONS

Three-month long Yoga practice improved HRV in early postmenopausal women significantly and has the potential to attenuate the CVD risk in postmenopausal women.

Effect of physical activity on cardiac autonomic function of dairy cows on commercial dairy farms

Interbeat interval data were collected from 219 Holstein cows in 2 smaller-scale farms and 3 larger-scale farms to investigate the effects of posture (standing vs. lying), rumination (rumination vs. no rumination) and feeding on baseline values of heart rate (HR) and heart rate variability (HRV) parameters reflecting vagal and sympathetic activity. A General Linear Model was used for detecting factors (parity, milking technology, herd size) having possible effects on HRV calculated for undisturbed lying posture. Basal values of cardiac parameters were also compared between larger and smaller-scale farms. Neither parity nor milking technology affected HRV parameters. Sympathetic activity increased in the order of lying, ruminating when lying, standing, ruminating when standing and feeding on both sizes of farms. Vagal activity decreased in that order in both lower- and larger-scale farms. Rumination caused an increase in HR and a decrease in vagal tone in both lower- and larger-scale farms and an increase in sympathetic activity during lying in both farm sizes. Basal vagal activity was lower in larger-scale farms compared to smaller-scale farms, while greater sympathetic activity was found in cows housed on larger-scale farms. Our findings demonstrate that reference values of HRV parameters in lactating dairy cows cannot be generally defined for Holstein cattle as they are affected by physical activity and herd size. Higher HR and sympathetic activity at rest in larger-scale farms compared to farms with lower cow population might be associated with higher levels of social stress and therefore should be considered as a potential welfare concern.

Monitoring weekly heart rate variability in futsal players during the preseason: the importance of maintaining high vagal activity

This study aimed to compare the weekly natural log of the root-mean-square difference of successive normal inter-beat (RR) intervals (ln RMSSD_Weekly) and its coefficient of variation (ln RMSSD_CV) in response to 5 weeks of preseason training in professional male futsal players. A secondary aim was to assess the relationship between ln RMSSD_Weekly and ln RMSSD_CV. The ln RMSSD is a measure of cardiac-vagal activity, and ln RMSSD_CV represents the perturbations of cardiac autonomic homeostasis, which may be useful for assessing how athletes are coping with training. Ten futsal players had their resting ln RMSSD recorded prior to the first daily training session on four out of approximately five regular training days · week^-1. Session rating of perceived exertion (sRPE) was quantified for all training sessions. Despite weekly sRPE varying between 3455 ± 300 and 5243 ± 463 arbitrary units (a.u.), the group changes in ln RMSSD_Weekly were rated as unclear (using magnitude-based inference), although large inter-individual variability in ln RMSSD responses was observed. The ln RMSSD_CV in weeks 4 and 5 were likely lower than the previous weeks. A large and significant negative correlation (r = -0.53; CI 90%: -0.36; -0.67) was found between ln RMSSD and ln RMSSD_CV. Therefore, monitoring individual ln RMSSD responses is suggested since large inter-individual variations may exist in response to futsal training. In addition, higher values of ln RMSSD are associated with lower oscillations of cardiac autonomic activity.

Cardiac autonomic activity has a circadian rhythm in summer but not in winter in non-lactating pregnant dairy cows

This investigation was conducted to examine circadian and seasonal rhythms of heart rate and heart rate variability (HRV) by means of hour-by-hour recordings over 24h in a large population of non-lactating Holstein-Friesian pregnant cows [N=56, summer (June-July); N=61, winter (November-December)]. Data were collected during a 5-day period from each animal. Besides parameters of cardiac autonomic function [the high-frequency (HF) component of HRV and the ratio between the low-frequency (LF) and the HF components (LF/HF ratio)], the RR triangular index and Lmax were calculated. A clear circadian profile was observed for every parameter in summer. Heart rate elevated gradually with the course of the day from 7:00 to 17:00 o'clock and then slightly decreased from 18:00 to 6:00. Sympathovagal balance shifted towards sympathetic dominance during the daytime (increased LF/HF ratio), whereas parasympathetic activity was predominant during the night (increased HF). Lmax reflected a chaotic behavior of heart rate fluctuations during the afternoon in summer. Decreased values of RR triangular index indicated a sensitive period for cows between 14:00 and 16:00 o'clock in summer. During winter, except for the RR triangular (RRtri) index reflecting a high overall variability in R-R intervals between 12:00 and 23:00 o'clock, heart rate and HRV showed no periodicity over the 24-h period. The results suggest an impaired cardiac autonomic function during daytime in summer. HF, Lmax and RRtri index showed seasonal differences for both daytime and nighttime. Heart rate was higher in summer than in winter during the daytime, whereas the LF/HF ratio was higher in winter during the nighttime. Circadian and seasonal rhythms of cardiovascular function are presumably related to the differing temperature, and animal activity associated with summer and winter. As all of the investigated parameters are commonly used in bovine HRV research, these findings have practical implications for behavioral, physiological and welfare studies on dairy cattle.