Index Of Sympathovagal Balance Research Articles

Indoor air pollution impacts cardiovascular autonomic control during sleep and the inflammatory profile

The present study explores the modifications of cardiovascular autonomic control (CAC) during wake and sleep time and the systemic inflammatory profile associated with exposure to indoor air pollution (IAP) in a cohort of healthy subjects.Twenty healthy volunteers were enrolled. Indoor levels of fine particulate matter (PM2.5), nitrogen dioxide (NO2) and volatile organic compounds (VOCs) were monitored using a portable detector for 7 days. Together, a 7-day monitoring was performed through a wireless patch that continuously recorded electrocardiogram, respiratory activity and actigraphy. Indexes of CAC during wake and sleep time were derived from the biosignals: heart rate and low-frequency to high-frequency ratio (LF/HF), index of sympathovagal balance with higher values corresponding to a predominance of the sympathetic branch. Cyclic variation of heart rate index (CVHRI events/hour) during sleep, a proxy for the evaluation of sleep apnea, was assessed for each night. After the monitoring, blood samples were collected to assess the inflammatory profile. Regression and correlation analyses were performed.A positive association between VOC exposure and the CVHRI (Δ% = +0.2% for 1 μg/m3 VOCs, p = 0.008) was found. The CVHRI was also positively associated with LF/HF during sleep, thus higher CVHRI values corresponded to a shift of the sympathovagal balance towards a sympathetic predominance (r = 0.52; p = 0.018). NO2 exposure was positively associated with both the pro-inflammatory biomarker TREM-1 and the anti-inflammatory biomarker IL-10 (Δ% = +1.2% and Δ% = +2.4%, for 1 μg/m3 NO2; p = 0.005 and p = 0.022, respectively).The study highlights a possible causal relationship between IAP exposure and higher risk of sleep apnea events, associated with impaired CAC during sleep, and a pro-inflammatory state counterbalanced by an increased anti-inflammatory response in healthy subjects. This process may be disrupted in vulnerable populations, leading to a harmful chronic pro-inflammatory profile. Thus, IAP may emerge as a critical and often neglected risk factor for the public health that can be addressed through targeted preventive interventions.

Abstract WP289: Insufficient Low-Frequency Blood Pressure Activity Under Orthostatic Stress Predicts Blunted Night-to-Day Blood Pressure Dipping in Patients With Ischemic Cerebrovascular Disease

Introduction: Blunted night-to-day blood pressure (BP) dipping was common in ischemic cerebrovascular disease (ICVD). BP dipping could be influenced by baroreflex, which stabilized BP by regulating sympathovagal balance. We sought to determine the relationship between baroreflex function and BP dipping in patients with ICVD. Methods: Patients with ICVD stable for at least 3 days were enrolled. Beat-to-beat BP and ECG were monitored in 3 phases of active standing [supine (S), supine to upright (SU), upright (U), 4 min each]. Baroreflex function was evaluated by time-domain and frequency-domain baroreflex sensitivity (BRS) and by indices of sympathovagal balance [low (0.04-0.15 Hz) to high (0.15-0.4 Hz) frequency ratio (LHR) of systolic BP (SBP) and RR interval (RRI)]. BP dipping was measured as percentage with 24h ambulatory BP monitoring. SBP dipping <0 was defined as reverse BP dipping. Results: Among 66 patients, mean SBP dipping was 3.54% ± 6.85%. SBP dipping was positively related to BP-LHR SU (Spearman r=0.258, p=0.036), but had no significant correlation with time-domain and frequency-domain BRS, LHR S and LHR U of BP and RRI, or RRI-LHR SU (Table 1). Lower log BP-LHR SU was indicative of less SBP dipping [β (95% CI): 6.53 (1.67-11.40), p=0.009] and the presence of reverse BP dipping [OR (95% CI): 0.11 (0.02-0.65), p=0.015], even after adjusting age, sex, vascular risk factors, 24h mean BP level, NIHSS and mRS scores (Table 2). Conclusions: Low BP-LHR SU , which suggested sympathetic underactivation of BP activity during the orthostasis-stimulated baroreflex engagement, might be a pathophysiological link between baroreflex impairment and blunted BP dipping in ICVD.

Stress influence on real-world driving identified by monitoring heart rate variability and morphologic variability of electrocardiogram signals: the case of intercity roads

Objectives. This study examines which of the heart rate variability (HRV) and morphologic variability (MV) metrics may have the highest accuracy in different stress detection during real-world driving. Methods. The cross-sectional study was carried out among 93 intercity mini-bus male drivers aged 22–67 years. The Trillium 5000 Holter Recorder and GARMIN Virb Elite camera were used to determine heart rate and vehicle speed measurements along the path, respectively. We considered the HRV and MV metrics of electrocardiogram (ECG) signals including the mean RR interval (mRR), mean heart rate (mHR), normalized low-frequency spectrum (nLF), normalized high-frequency spectrum (nHF), normalized very low-frequency spectrum (nVLF), difference of normalized low-frequency spectrum and normalized high-frequency spectrum (dLFHF), and sympathovagal balance index (SVI). Results. The analysis showed that the HRV metrics mHR, mRR, nVLF, nLF, nHF, dLFHF and SVI are effective in mental stress detection while driving as compared to rest time. We obtained a high accuracy of stress detection for MV metrics as compared to the traditional HRV analysis, of approximately 92%. Conclusions. Our findings indicate that driver stress could be detected with an accuracy of 92% using MV metrics as an accurate physiological index of the driver’s state.

Heart rate variability and tension-type headache: A population-based cross-sectional study

BackgroundThe relationship between tension-type headache (TTH) and autonomic functions is poorly understood, although TTH is one of the most prevalent disorders in the general population. The aim of this study was to investigate the direct and indirect effects of TTH on the autonomic functions measured by heart rate variability (HRV). MethodsThis population-based cross-sectional study was carried out in the general population of Ulaanbaatar between July and September in 2020. After physical examination, trained researchers applied structured interviews to examine the remote history of TTH and mental distress, followed by a recording of HRV to detect autonomic activity. Psychological factors and the quality of life were measured using Hospital Anxiety Depression Scale (HADS), Pittsburgh Sleep Quality Index (PSQI), and the World Health Organization Quality of Life–Brief (WHOQOL-BREF). Binary logistic regression and GLM mediation model analysis were used to examine the effects of risk factors on the associations between TTH and autonomic functions. ResultsAmong participants (n = 217, mean age=41.8 ± 11.5 years), a total of 117 (53.9%) participants had a remote history of TTH. The age and sex-adjusted prevalence was 43%. Groups did not differ statistically in the HRV indices. LF/HF (ratio of low-frequency to high frequency), the index of sympathovagal balance, was correlated with the HADS anxiety. TTH was associated with mental distress. Binary logistic regression analysis confirms the relationship suggesting that TTH was associated with increased likelihood of mental distress, and decreasing RMSSD (root mean square of the sum of the squares of differences between adjacent NN intervals) and pNN50 (NN50 divided by the total number of NN intervals) were the independent predictors of TTH. GLM mediation model indicated that the relationship between TTH and RMSSD was mediated by mental distress. ConclusionsThe present study suggests that mental distress is a critical factor in the association between TTH and autonomic dysfunction. Additionally, our findings demonstrate the influence of age and gender on TTH. These results highlight the need to understand the mechanisms underlying pathophysiology to facilitate targeted and efficacious prevention and management approaches for TTH.

Correlation between heart rate variability and polysomnography-derived scores of obstructive sleep apnea.

Obstructive sleep apnea (OSA) is one of the most common sleep disorders and affects nearly a billion people worldwide. Furthermore, it is estimated that many patients with OSA are underdiagnosed, which contributes to the development of comorbidities, such as cardiac autonomic imbalance, leading to high cardiac risk. Heart rate variability (HRV) is a non-invasive, widely used approach to evaluating neural control of the heart. This study evaluates the relationship between HRV indices and the presence and severity of OSA. We hypothesize that HRV, especially the nonlinear methods, can serve as an easy-to-collect marker for OSA early risk stratification. Polysomnography (PSG) exams of 157 patients were classified into four groups: OSA-free (N = 26), OSA-mild (N = 39), OSA-moderate (N = 37), and OSA-severe (N = 55). The electrocardiogram was extracted from the PSG recordings, and a 15-min beat-by-beat series of RR intervals were generated every hour during the first 6h of sleep. Linear and nonlinear HRV approaches were employed to calculate 32 indices of HRV. Specifically, time- and frequency-domain, symbolic analysis, entropy measures, heart rate fragmentation, acceleration and deceleration capacities, asymmetry measures, and fractal analysis. Results with indices of sympathovagal balance provided support to reinforce previous knowledge that patients with OSA have sympathetic overactivity. Nonlinear indices showed that HRV dynamics of patients with OSA display a loss of physiologic complexity that could contribute to their higher risk of development of cardiovascular disease. Moreover, many HRV indices were found to be linked with clinical scores of PSG. Therefore, a complete set of HRV indices, especially the ones obtained by the nonlinear approaches, can bring valuable information about the presence and severity of OSA, suggesting that HRV can be helpful for in a quick diagnosis of OSA, and supporting early interventions that could potentially reduce the development of comorbidities.

Correlation between heart rate variability and polysomnography‐derived scores of severities for obstructive sleep apnea

Obstructive sleep apnea (OSA) is one of the most common sleep disorders and affects nearly a billion people worldwide. Furthermore, it is estimated that many patients with OSA are underdiagnosed, which contributes to the development of comorbidities, such as cardiac autonomic imbalance, leading to high cardiac risk. Heart rate variability (HRV) is a non‐invasive, widely used approach to evaluate neural control of the heart. This study aims to seek the relationship between HRV indices and the presence and severity of OSA. Polysomnography (PSG) exams of 157 patients were classified into four groups: OSA‐free (N=26), mild (N=39), moderate (N=37), and severe OSA (N=55). The electrocardiogram was extracted from the PSG, and a 15‐min beat‐by‐beat series of RR intervals was generated every hour during the first 6 h of sleep. Linear and nonlinear HRV approaches were employed to calculate a variety of indices of HRV. Specifically, time‐ and frequency‐domain, symbolic analysis, entropy measures, heart rate fragmentation, acceleration and deceleration capacities, asymmetry measures, and fractal analysis (detrended fluctuation analysis). Results with indices of sympathovagal balance reinforced previous findings that patients with OSA have sympathetic overactivity. Nonlinear indices showed that these patients suffer from a loss of physiologic complexity, contributing to their higher risk of development of cardiovascular disease. Moreover, as shown in the table below, many HRV indices presented statistically significant correlation with PSG's clinical scores: apnea/hypopnea index (AHI), microarousal index (MI), percentage of the total sleep time that the patient was with oxygen saturation below 90% (T90), and oxygen saturation nadir during sleep (SatMin). Therefore, a complete set of HRV indices, especially the nonlinear ones, can bring valuable information about the presence and severity of OSA, suggesting that HRV can be helpful in a quick diagnosis of OSA, potentially reducing the development of comorbidities.

Blunted Cardiac Response to Head-up Tilt Occurs in Sickle Cell Disease but Not Healthy Controls

Introduction: Sickle cell disease (SCD) is characterized by microvascular occlusion from sickled red blood cells that can develop into full-blown vaso-occlusive crisis. We hypothesize that abnormal autonomic function plays a role in promoting microvascular occlusion in SCD. Head-up tilt (HUT) evokes a strong sympathetic response to the transient drop in blood pressure resulting from blood pooling in the lower extremities. Baroreflex regulation leads to heart rate (HR) increase and peripheral vasoconstriction. In this study, we subjected control and SCD subjects to the HUT test to assess their autonomic response.Objective: To evaluate the autonomic response and determine the relative contributions of the cardiac and peripheral vascular responses to HUT in SCD compared to control subjects.Experimental Protocols: 22 SCD and 17 control (healthy and sickle cell trait) subjects were recruited at Children's Hospital Los Angeles. Each subject laid supine on the tilt table for 5 minutes prior to being tilted up to 70° for 7 minutes, and subsequently returned to supine. Electrocardiogram, respiration, continuous blood pressure and photoplethysmograph (PPG) were measured continuously throughout the protocol. PPG amplitude was taken to represent peripheral blood flow (PBF) since reductions in PPG amplitude reflect vasoconstriction.Analysis: Mean systolic blood pressure (SBP), HR and PBF were calculated over 2 minutes under baseline and HUT conditions. In HUT, we analyzed the physiological responses following 3 minutes of stabilization. Heart rate variability indices: high frequency power (HFP) and low-to-high ratio (LHR), reflecting parasympathetic activity and sympatho-vagal balance respectively, were also computed. Percent change from baseline of all parameters were computed to assess the tilt response after adjusting for their baseline values.Results: There was not a significant change in SBP from baseline to HUT across all subjects. To maintain blood pressure, the response to HUT was categorized into 3 groups: 1) those who had increased HR (>15%) AND decreased PBF (>20%) from baseline, 2) those who only had increased HR, and 3) those who only had decreased PBF (Fig.1). While Group 1 and 2 responses were found in both controls and SCD, Group 3 responses consisted only of SCD subjects (Table 1). Although mean HR at baseline was not different from the other two groups, we found that HFP of Group 3 was lower compared to Group 1 (p = 0.0007) and Group 2 (p = 0.0396), while Group 3 LHR was higher than Group 1 (p = 0.0020).Discussion & Conclusions: HUT is standard and well-recognized assessment of the autonomic response to transient drop in blood pressure. While most subjects maintained their SBP by increasing both HR and peripheral resistance, a subset of SCD subjects responded to HUT via only peripheral vasoconstriction. Moreover, these SCD subjects had significantly lower parasympathetic HR modulation at baseline as reflected by lower HFP and higher LHR, an index of sympatho-vagal balance. The findings suggest that baroreflex control of heart rate during HUT in this subset of SCD subjects was blunted due to low vagal and high cardiac sympathetic tone, whereas baroreflex control of peripheral vascular resistance remained relatively intact. These data provide further evidence that there is significant autonomic dysfunction in some patients with SCD. This hypersensitivity to vasoconstriction would decrease microvascular flow and would likely lead to vaso-occlusion. We speculate that this subset of SCD subjects may also be the most vulnerable to reduced PBF and thus VOC during orthostatic stress. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Acute hydrogen-rich water ingestion stimulates cardiac autonomic activity in healthy females

Background: Hydrogen-rich water (HRW) has been shown to have a stimulating effect on the human body. Objective: The aim of the study was to assess the influence of acute HRW intake on autonomic cardiac regulation during 50 min of rest sitting. Methods: Fourteen healthy females (age 21.7 ± 1.2 years, body mass 67.8 ± 8.7 kg, height 167 ± 5.5 cm) took part in this double-blind, randomized, placebo-controlled trial with crossover design. Heart rate variability (HRV) was monitored in the sitting position after administration of 1260 ml of HRW or placebo. Time domain indexes of HRV as the square root of the mean of the squares of differences between adjacent RR intervals (RMSSD), the standard deviation of all RR intervals (SDNN) and the ratio of SDNN/RMSSD as an index of sympatho-vagal balance were used to assess autonomic cardiac response. The values were transformed using natural logarithm (Ln). Results: After administration of HRW, we found significantly increased ratio Ln SDNN/RMSSD when comparing it to placebo in 25 min (HRW: 0.40 ± 0.30, placebo: 0.26 ± 0.25, p = .049) and 35 min (HRW: 0.44 ± 0.30, placebo: 0.28 ± 0.28, p = .029) of rest sitting. Ln SDNN was significantly increased after HRW administration when compared to placebo in 45 min (HRW: 4.41 ± 0.42 ms, placebo: 4.28 ± 0.31 ms, p = .049) of rest sitting. Conclusions: Acute HRW ingestion induced a relative increase in sympathetic activity between 25 and 35 min post-ingestion, whereas vagal activity was not affected.

Obesity-Induced Heart Rate Variability Impairment and Decreased Systolic Function in Obese Male Dogs.

Simple SummaryObesity in dogs can induce many adverse health effects including musculoskeletal problems, respiratory distress, metabolic syndrome, and cardiovascular diseases. In humans with obesity, heart rate variability (HRV) is used to identify and predict the risk of cardiovascular diseases. However, this predictive tool has never been used in veterinary medicine, and the relationship between obesity and HRV has rarely been investigated. In this study, we investigated HRV, plasma oxidative stress (MDA), and cardiac function in obese male dogs. We hypothesized that obese male dogs have decreased cardiac function and impaired HRV compared to non-obese dogs. Our study found that obese dogs have decreased cardiac systolic function and impaired HRV, as indicated by reduced percentages of cardiac contraction and impaired cardiac autonomic activity compared to non-obese dogs. We concluded that obesity can decrease systolic function and cause HRV impairment, which might increase the risk of cardiovascular disease in dogs. In addition, HRV might be used as a predictive or prognostic tool in the prevention of cardiovascular disease in obese dogs.Obesity can induce cardiovascular diseases in both humans and animals. Heart rate variability (HRV) is an indicator of sympathovagal balance and is used to identify cardiovascular diseases in humans. However, HRV and cardiac function have rarely been investigated in obese dogs. This study investigated the effect of obesity on oxidative stress, HRV, and cardiac function in obese and non-obese dogs. The nine-scale body condition score (BCS) system was used to determine obesity. Thirty small breed dogs were divided into a normal weight group (n = 15) and an obese group (n = 15). All dogs underwent physical examination, plasma malondialdehyde (MDA) measurement, electrocardiography, echocardiography, and two hours of Holter monitoring. This study found that obese dogs had increased plasma MDA and sympathovagal imbalance, which was indicated by impaired time and frequency domains compared to normal weight dogs. Although cardiac function was within normal limits, the echocardiographic study found that the obese dogs had reduced cardiac wall thickness and lower systolic function, as indicated by a reduction in %ejection fraction, %fractional shortening, increased left ventricular (LV) internal diameter during systole, and LV end-systolic volume compared to normal weight dogs. This study concluded that obesity in dogs can induce increased plasma oxidative stress, impaired HRV, and reduced cardiac systolic function compared to non-obese dogs.

Workload assessment of air traffic controllers

Air traffic controllers (ATCOs) are exposed to high workload even during routine operations. Their job carries a lot of responsibility and consists of complex tasks. In order to enhance high safety standards, a systematic evaluation of workload levels is required. This study explores an objective measurement of workload. Heart activity of ATCOs was monitored in order to indicate psychological status of ATCOs while being exposed to different levels of workload - in terms of changing traffic loads and airspace complexity. A standard method was used for the evaluation of heart activity. This method includes the frequency analysis in context of heart rate variability; time intervals of consecutive R waves in the heart activity record are assessed. The evaluation of the ratio of power in the low-frequency and high-frequency bands (indicator of sympathovagal balance) as well as parameters derived from fluctuation analysis were used. The results indicated that parameters of heart rate variability based on spectral analysis were significant in case of workload evaluation.

Application of Meridian Electrical Conductance in the Setting of Acute Ischemic Stroke: A Cross-Sectional Study.

Acupuncture is widely used for improving poststroke care. Knowing the condition of meridian can help traditional Chinese medicine (TCM) doctors make a tailored choice of acupoints for every patient. The establishment of an objective meridian energy measurement for acute ischemic stroke that can be used for future acupuncture treatment and research is an important area in stroke-assisted therapy. In this study, a total of 102 subjects diagnosed with acute ischemic stroke within 7 days of onset were recruited, and the meridian energy analysis device (MEAD) was used to record the meridian electrical conductance (MEC) values of twelve meridians on unaffected and affected limbs. We found that the MEC value of the twelve meridians on the affected limbs was significantly higher than that on the unaffected limbs (P=0.001). Compared with the unaffected limbs, there was a higher value of MEC on the affected limbs of the lung meridian, heart meridian, pericardium meridian, and small intestine meridian, with significant differences (P < 0.05, P < 0.001, P < 0.001, and P < 0.05, respectively). Further analysis revealed that the MEC values of both Yin and Yang meridians of the affected limbs were significantly higher than those of the unaffected limbs (P=0.001 and P < 0.05, respectively). Meanwhile, the mean of the index of sympathovagal balance in patients with acute ischemic stroke (5.49 ± 4.21) was higher than the normal range (1–1.5), indicating autonomic imbalance. The results of this study are consistent with TCM theory as well as clinical observation and pathological mechanisms, suggesting that the measurement of MEC values may be used as a supplementary diagnostic method for acupuncture in patients with acute ischemic stroke.

Autonomic cardiovascular control in older patients with acute infection and delirium: a pilot study of orthostatic stress responses

BackgroundAlterations in autonomic nervous system (ANS) activity might be involved in the pathophysiology of delirium. The aim was to explore autonomic cardiovascular control in older patients with and without delirium.MethodsFourteen patients (five with delirium) acutely admitted to the geriatric ward with an infection were enrolled in the study. Patients with atrial fibrillation, a pacemaker, or on treatment with beta-blockers, calcium channel blockers or acetylcholinesterase inhibitors were not eligible.Continuous, non-invasive hemodynamic variables were measured during supine rest (5 min) and head-up tilt (HUT) to 15 degrees (10 min). Heart rate (HR), blood pressure (BP) and stroke volume (SV) were recorded beat-to-beat. Cardiac output (CO), total peripheral resistance (TPR), end-diastolic volume (EDV) and heart rate variability (HRV) values were calculated.ResultsMedian age was 86 years. HR, BP, SV, CO, TPR and EDV were similar across the two groups at rest, but there was a trend towards a greater increase in systolic BP and HR during HUT in the delirium group. At rest, all HRV indices were higher in the delirium group, but the differences were not statistically significant. During HUT, the delirium group had higher power spectral density (PSD) (representing total variability) (p = 0.06) and a lower low frequency (LF)/high frequency (HF)-ratio (an index of sympathovagal balance) than the control group (p = 0.06). Also, delirious patients had a significantly greater reduction in standard deviation of RR-intervals (SDNN) (representing total variability) from baseline than controls (p = 0.01) during HUT.ConclusionsThis explorative pilot study on autonomic cardiovascular control in delirium suggests that there may be differences in HRV that should be further investigated in larger samples.

Sympathetic responses induced by radiofrequency catheter ablation of atrial fibrillation.

Radiofrequency catheter ablation (RFCA) is a frequently performed procedure in patients with atrial fibrillation. Prior studies have shown that the RFCA may directly stimulate vagal afferents during the procedure, whereas the vagal tone assessed by heart rate variability (HRV) is lowered weeks after the RFCA procedure. The effects of RFCA performed in the left atrium on sympathetic nerve activity have not been assessed. In the present study, we hypothesized that RFCA would lower muscle sympathetic nerve activity (MSNA) during ablation and would raise MSNA 1 day postablation. A total of 18 patients were studied. In protocol 1 ( n = 10), electrocardiogram, blood pressure, and MSNA in the peroneal nerve were recorded through the RFCA procedure performed in the electrophysiology laboratory. In protocol 2, eight patients were studied before the procedure and 1 day postablation. RFCA led to a decrease in MSNA immediately after the procedure (25.4 ± 3.2 to 17.2 ± 3.8 bursts/min, P < 0.05). Cardiac parasympathetic activity was determined using indexes of HRV and increased during the procedure. One day postablation, MSNA was above baseline values (21.3 ± 3.7 to 35.7 ± 2.6 bursts/min, P < 0.05). HRV indexes of cardiac parasympathetic activity fell, and the HRV index of sympathovagal balance was not significantly altered. The results show that RFCA raised cardiac parasympathetic activity and decreased MSNA during the procedure. One day postablation, MSNA rose and cardiac parasympathetic activity fell. In addition, RFCA evokes differentiated sympathetic responses directed to the heart and skeletal muscles. NEW & NOTEWORTHY The effects of radiofrequency catheter ablation performed in the left atrium on muscle sympathetic nerve activity (MSNA) have not been assessed. The results of this study show that radiofrequency catheter ablation raised cardiac parasympathetic activity and decreased MSNA during the procedure. One day postablation, MSNA rose and cardiac parasympathetic activity fell. We speculate that the partial autonomic afferent denervation induces these effects on autonomic activity.

A New Sympathovagal Balance Index from Electrodermal Activity and Instantaneous Vagal Dynamics: A Preliminary Cold Pressor Study.

Sympathovagal balance, an autonomic index resulting from the sympathetic and parasympathetic influences on cardiovascular control, has been extensively used in the research practice. The current assessment is based on analyzing Heart Rate Variability (HRV) series in the frequency domain by regarding the ratio between the low and high frequency components (LF/HF). Nevertheless, LF and HF powers are known to be both influenced by vagal activity which strongly bias the accuracy of this method. To this extent, in this study we combine time-varying estimates from electrodermal activity (EDA) and HRV to propose a novel index of sympathovagal balance. Particularly, sympathetic activity is estimated from the EDA power calculated within the 0.045-0.25Hz bandwidth $(EDA_{Symp})$, whereas parasympathetic dynamics is measured instantaneously through a point-process modeling framework devised for heartbeat dynamics $(HF_{pp})$. We test our new index $SV = EDA_{Symp/HF_{pp}}$ on data gathered from 22 healthy subjects (7 females and 15 males) undergoing a 3 minutes gold standard protocol for sympathetic elicitation as the cold-pressor test (CPT). Results show that the activation of the proposed sympathovagal tone is consistent with CPT elicitation and is associated with a significantly higher statistical discriminant power than the standard LF/HF ratio, also revealing different dynamics between female and male subjects.

Heart rate variability parameters in children with ventricular preexcitation.

The autonomic nervous system has a regulatory effect on cardiac electrophysiology and arrhythmogenesis. We aimed to assess cardiac autonomic status using heart rate variability (HRV) parameters in children with ventricular preexcitation. The electrocardiography, Holter monitoring, transesophageal electrophysiological study (TEEPS), and invasive electrophysiological study (EPS) results of ventricular preexcitation patients obtained over a 7-year period in our clinic were evaluated. According to the TEEPS results, patients' accessory pathway conduction was classified as adverse (n = 40) or nonadverse (n = 25). The HRV parameters of patients were compared according to tachycardia inducibility that assessed by TEEPS and EPS. Also, HRV parameters were compared in patients with adverse and nonadverse pathway conduction. Further, the HRV parameters of preexcitation patients were compared with those of healthy controls. LF/HF, the best measure of sympathovagal balance, was statistically higher in patients with adverse conduction than in patients without adverse conduction and controls (P=0.001). The LF/HF ratio was higher in ventricular preexcitation patients with inducible tachycardia than those without in EPS (P=0.001). In addition, the LF/HF ratio was higher in symptomatic ventricular preexcitation patients than asymptomatic ones (P=0.001). No difference in HRV parameters was found between preexcitation patients and controls. Autonomic tonus in patients with ventricular preexcitation may affect accessory pathway conduction properties, tachycardia inducibility, and symptomology. The indicator of sympathovagal balance, LF/HF ratio, increased in ventricular preexcitation patients with inducible tachycardia and those that were symptomatic.

INTERDEPENDENCE OF VARIABILITY OF THE HEART RHYTHM WITH DAILY PROFILE OF ARTERIAL PRESSURE IN PATIENTS WITH ARTERIAL HYPERTENSION

The article analyzes the interrelation of the heart rate variability with the daily profile of arterial pressure in patients with arterial hypertension.Objective: to study the relationship between heart variability indices the daily profile of blood pressure in patients with arterial hypertension I-II stage.Material and methods. A survey of 145 patients with stage I and II hypertension, aged 29 to 53 years old (average age - 46.75 ± 0.56 years) was performed. According to a result of 24-hour daily blood pressure monitoring, all patients were divided into 3 groups: 62 patients with normal blood pressure decrease at night (dippers); 67 patients with insufficient decrease in blood pressure at night (non-dipper); 16 patients with excessive nightly decrease in blood pressure (over-dipper).Results: under background conditions patients with an insufficient (non-dipper) or surplus (over-dipper) decline HELL at night were characterized by less general power of spectrum (ТР) and VLF of modulations. In addition, substantial increase of sympatic trend in (non-dipper) and parasympathetic trend in (over-dipper) attracts attention. Thus, LF part of vibrations of LF% in the group of patients of made 35,34±2,25%, and significantly exceeded the value of analogical index in the group of (22,75±1,15%, p <0,01), but the part of HF of vibrations of HF% in the group of patients of over-dipper, having made 32,96±1,18%, significantly exceeded the value for an analogical index in the group of (14,92±0,95%, p <0,01) and (17,43±1,12%,p <0,02). Non-dipper were characterized by the least values of cute modulations and index of sympatho-vagal balance (p <0,01).Conclusion. It has been established that, the inherent vegetative maintenance of cardiac activity was preserved for the patients in the category of dipper and overdipper. At the same time, patients who have a daily profile of overseas dippery type, are characterized by adequate functioning of the sympathetic department of the autonomic nervous system against a background of high activity of the parasympathetic link. Patients who belong to the non-dipper category show a decrease in the adaptive capacity of the sympathetic nervous system against a background of hyperparasympathicotonia in a state of rest and an adequate response to parasympathetic modulation during the loading test.

Hereditary angioedema: Assessing the hypothesis for underlying autonomic dysfunction.

BackgroundAttacks of Hereditary Angioedema due to C1-inhibitor deficiency (C1-INH-HAE)are often triggered by stressful events/hormonal changes.ObjectiveOur study evaluates the relationship between autonomic nervous system (ANS) and contact/complement system activation.MethodsTwenty-three HAE patients (6 males, mean age 47.5±11.4 years) during remission and 24 healthy controls (8 males, mean age 45.3±10.6 years) were studied. ECG, beat-by-beat blood pressure, respiratory activity were continuously recorded during rest (10’) and 75-degrees-head-up tilt (10’). C1-INH, C4, cleaved high molecular weight kininogen (cHK) were assessed; in 16 patients and 11 controls plasma catecholamines were also evaluated. Spectral analysis of heart rate variability allowed extraction of low-(LF) and high-(HF) frequency components, markers of sympathetic and vagal modulation respectively.ResultsHAE patients showed higher mean systolic arterial pressure (SAP) than controls during both rest and tilt. Tilt induced a significant increase in SAP and its variability only in controls. Although sympathetic modulation (LFnu) increased significantly with tilt in both groups, LF/HF ratio, index of sympathovagal balance, increased significantly only in controls.At rest HAE patients showed higher noradrenaline values (301.4±132.9 pg/ml vs 210.5±89.6pg/ml, p = 0.05). Moreover, in patients tilt was associated with a significant increase in cHK, marker of contact system activation (49.5 ± 7.5% after T vs 47.1 ± 7.8% at R, p = 0.01).ConclusionsOur data are consistent with altered ANS modulation in HAE patients, i.e. increased sympathetic activation at rest and blunted response to orthostatic challenge. Tilt test-induced increased HK cleavage suggests a link between stress and bradykinin production.

Differential associations of lower cardiac vagal tone with insulin resistance and insulin secretion in recently diagnosed type 1 and type 2 diabetes

ObjectiveIt is unclear to which extent altered insulin sensitivity/secretion contribute to the development of diabetic cardiovascular autonomic neuropathy (CAN) characterized by diminished heart rate variability (HRV). We hypothesised that lower HRV is differentially associated with measures of insulin resistance and insulin secretion in recent-onset type 1 and type 2 diabetes. Materials/MethodsThis cross-sectional study included participants from the German Diabetes Study with type 1 (n=275) or type 2 diabetes (n=450) with known diabetes duration ≤1year and glucose-tolerant controls (n=81). Four time domain and frequency domain HRV measures each, reflecting vagal and/or sympathetic modulation were determined over 3h during a hyperinsulinaemic-euglycaemic clamp. Insulin sensitivity was calculated as the M-value, while insulin secretion was determined by glucagon-stimulated incremental C-peptide (ΔC-peptide). ResultsAfter adjustment for sex, age, BMI, smoking, and HbA1c, both M-value and ΔC-peptide were lower in the diabetes groups compared to controls (P<0.05). In multiple linear regression analyses after Bonferroni correction, vagus-mediated HRV indices were positively associated with M-value in both diabetes types (P<0.05) and inversely associated with ΔC-peptide only in participants with type 1 diabetes (P<0.05). In type 2 diabetes, the low-frequency/high-frequency (LF/HF) power as an indicator of sympathovagal balance was weakly inversely associated with M-value. ConclusionsInsulin resistance may contribute to the development of early cardiovagal suppression rather than sympathetic predominance in both diabetes types, while in type 1 diabetes a lower glucagon-stimulated insulin secretion is linked to a possibly compensatory higher parasympathetic tone. Whether interventions aimed at reducing insulin resistance could also reduce the risk of CAN remains to be established.

Effect of unconjugated hyperbilirubinemia on neonatal autonomic functions: evaluation by heart rate variability

Background: Serum bilirubin levels beyond the physiological limits, may lead to alterations in autonomic regulation in a newborn infant. Heart rate variability (HRV), is a noninvasive and quantitative marker of the activity of the autonomic nervous system (ANS). To date, few studies have demonstrated the undesirable effects of severe unconjugated hyperbilirubinemia (UHB) on autonomic functions, and only one study has used HRV as a marker of the autonomic activity. However, the relationship between altered cardiac autonomic functions and UHB by using the HRV derived from 24-hour Holter electrocardiography (ECG) recording has not been investigated previously.Objective: We aimed to assess whether a relationship exists between severe UHB and cardiac autonomic dysfunction by evaluating HRV via 24-hour Holter ECG recording.Methods: This single-center, prospective, case-control study was conducted on 50 full-term newborn infants with severe UHB requiring phototherapy and 50 healthy infants as controls. HRV assessment was performed by using 24-hour Holter ECG recording.Results: There was no significant difference in terms of mean average heart rate, mean maximum heart rate and mean RR duration between the groups. However, mean minimum heart rate was significantly lower in the study group. When 24-hour time and frequency domain parameters were compared, time and frequency domain parameters rMSDD as well as high frequency (HF), which represent parasymphathetic activity, were significantly higher in the study group. Furthermore, low frequency to high frequency (LF/HF) ratio, that serves as an indicator of sympathovagal balance, was significantly lower in the study group.Conclusion: Severe UHB may cause cardiac autonomic dysfunction in favor of parasympathetic predominance in jaundiced neonates.

0289 CARDIOVASCULAR AUTONOMIC DYSFUNCTION IN PATIENTS WITH INSOMNIA AND OBJECTIVE SHORT SLEEP DURATION

Objective sleep duration has been proposed as a biological marker of insomnia severity. Based on this conceptualization, two phenotypes have emerged. Insomnia with near-normal sleep duration (NNSD) appears to be related to increased psychological symptoms. Conversely, insomnia with short sleep duration (SSD) is associated with an increased risk of future cardiovascular morbidity. Reduced heart rate variability (HRV) has also been implicated in the pathophysiology of cardiac conditions; however, there is little data on whether this physiological marker of cardiovascular function differs based on sleep duration in chronic insomnia patients. Participants were 189 adults (Mage = 49.8 years, SD = 11.8; 63.5% female) who met diagnostic criteria for insomnia. Objective sleep duration was based on total sleep time averaged across two consecutive nights of polysomnography (PSG). The sample was divided into two groups based on sleep duration - shorter (n = 48) or longer (n = 141) than 6 hours. Electrocardiogram data (2-min epochs) derived from PSG were edited and analyzed to obtain HRV during N2, N3, and rapid-eye movement (REM) sleep. HRV measures included high frequency (HF), an index of parasympathetic activation, and the ratio of low to high frequency (LF/HF ratio), an index of sympathovagal balance. Compared to insomnia patients with NNSD, those with SSD had significantly reduced HF-HRV during N2 (45.2 vs. 40.8, p<.001) and REM sleep (34.1 vs. 32.2, p=.007). Additionally, insomnia patients with SSD had significantly greater LF/HF ratio during N2 (1.12 vs. 1.06, p=.002) and REM sleep (1.26 vs. 1.21, p=.009) compared to insomnia patients with NNSD. No significant differences in N3 were found between phenotypes. Overall, insomnia patients with objective SSD showed significantly dampened parasympathetic activation and elevated sympathovagal imbalance relative to their counterparts with NNSD. It is posited that the pathophysiological responses related to short sleep may exacerbate a nocturnal stress response, expediting the progression of cardiovascular morbidity. These findings highlight the importance of treating insomnia, as treatment may reduce risk of cardiovascular disease. Supported by National Institute of Mental Health Grant (RO1MH079188 & R01MH60413) and by the Fonds de recherche du Québec - Santé (32207).