Heart Rate Variability Parameters In Patients Research Articles

Inter- and intra-examiner reliability of short-term measurement of heart rate variability on rest in patients hospitalized with COVID-19

Measures reflecting cardiac sympathovagal activity, particularly those associated with heart rate variability (HRV), are widely recognized and utilized in both scientific and clinical contexts. This study aimed to assess the inter- and intra-examiner reliability of short-term HRV parameters in patients hospitalized with coronavirus disease 2019 (COVID-19). A total of 103 patients (both sexes) diagnosed with COVID-19 were included in the study. HRV was analyzed using both linear and nonlinear methods. Reliability was evaluated through intraclass correlation coefficient (ICC2.1), minimum detectable change (MDC), standard error of measurement (SEM), and coefficient of variation (CV). According to Fleiss’ criteria, excellent reliability was demonstrated, with ICC values ranging from 0.970 to 0.999 for Examiner 1, and from 0.956 to 0.999, for Examiner 2. In the inter-examiner analysis, the ICCs of HRV parameters ranged from 0.972 to 0.999. SEM values for intra-examiner reliability for Examiner 1 ranged from 0.02 to 5.64, with MDC values from 0.05 to 15.64, and CV (%) from 0.28 to 8.04. For Examiner 2, SEM values ranged from 0.02 to 8.18, MDC values from 0.05 to 22.68, and CV (%) from 0.24 to 8.14. For inter-examiner reliability, SEM values ranged from 0.02 to 6.17, MDC from 0.06 to 17.11, and CV (%) from 0.34 to 9.81. Across all analyses, CVs for HRV parameters remained below 10%. Considering different time points and different examiners, short-term resting HRV measurements in patients hospitalized with COVID-19, as evaluated using a portable heart rate device, exhibit high reliability.

Effect of Piracetam and Iron Treatment on Heart Rate Variability in Patients With Breath-Holding Spell

BackgroundBreath-holding spells are a benign condition primarily seen in 3% to 5% of healthy children aged between six months and five years. Although no specific treatment is recommended due to its benign nature, iron and piracetam are used in severe or recurrent cases. We planned to compare the heart rate variability (HRV) before and after treatment with 24-hour Holter monitoring in patients receiving iron and piracetam treatment and investigate the treatment's effectiveness. MethodsTwenty-five patients who applied to the outpatient clinic between 2013 and 2015 due to breath-holding spells were included in the study. The patients who received piracetam and iron therapy and underwent 24-hour rhythm Holter monitoring were evaluated retrospectively. ResultsFourteen (56%) of these patients were evaluated as having cyanotic-type and 11 (44%) patients were assessed as having pale-type breath-holding spells. A significant difference was found only between hourly peak heart rate and total power in the group receiving iron treatment. Significant differences were also found among the minimum heart rate, mean heart rate, the standard deviation of RR intervals, the mean square root of the sum of the squares of their difference between adjacent RR intervals, spectpow, and low frequency before and after the treatment in the patients who started piracetam treatment (P < 0.05). ConclusionsOur study is critical as it is the first to investigate the effects of treatment options on various HRV in patients with breath-holding spells. There were statistically significant changes in HRV parameters in patients receiving piracetam, and the number of attacks decreased significantly. Piracetam treatment contributes positively to the breath-holding spell with regard to efficacy and HRV, therefore it can be used to treat breath-holding spells.

Heart rate variability in patients with acute ST-segment elevation myocardial infarction after COVID-19

Aim. To compare heart rate variability parameters in patients after a coronavirus disease 2019 (COVID-19) with acute ST elevation myocardial infarction (STEMI) during the inhospital and post-hospital periods.Material and methods. A total of 140 patients with STEMI were divided into 2 groups: I — patients with STEMI who had COVID-19 (n=52) in the period of 1,5-6 months before acute coronary syndrome, II — comparison group (n=88), which included patients with STEMI without prior COVID-19. All patients underwent infarct-related artery stenting within the first 24 hours from the onset. Heart rate variability (HRV) parameters were determined for all patients on days 2-3 and days 9-11 and 6 months after the hospitalization for STEMI.Results. Patients in group I showed more pronounced changes in HRV indicators on days 2-3 of STEMI: RMSSD (root square of successive RR intervals) by 21% (p=0,026), variations (Var) (the difference between the minimum and maximum RR intervals) by 33% (p=0,013), VLF (total very low-frequency HRV) by 7% (p=0,009) were higher, and HF (highfrequency HRV) by 40% (p=0,003), pNN50% (ratio of the number of consecutive RR interval pairs differing by &gt;50 ms to the total number of RR intervals) by 66% (p=0,038) were lower than in the control group, respectively. On days 9-11 of the disease in patients with a history of STEMI and COVID-19, in contrast to the control group, there was a more pronounced increase in the SDNN (standard deviation of RR intervals) by 46% (p=0,005), VLF by 42% (p=0,031), whereas in the control group there were an increase of only 22% (p=0,004) and 11% (p=0,022), respectively. The HF value in the main group increased by 25% (p=0,007), while in the control group it decreased by 19% (p=0,030). Six months after STEMI in the main group, the RMSSD decreased by 19% (p=0,009), Var by 16% (p=0,041), VLF by 30% (p=0,025), LF (low-frequency component HRV) by 11% (p=0,005), while the control group these parameters decreased by 20% (p=0,006), 21% (p=0,001), 9% (p=0,011), and 7% (p=0,016), respectively.Conclusion. In patients with STEMI and prior COVID-19, the initial HRV values differ from similar HRV parameters in patients with STEMI without prior COVID-19. In the hospital and post-hospital periods, the changes of HRV in patients with and without COVID-19 are multidirectional as follows: pronounced sympathetic hyperactivity predominates, and slower recovery of HRV in patients after COVID-19 predominates.

Heart rate variability modification as a predictive factor of sudden unexpected death in epilepsy: How far are we? A systematic review and meta-analysis.

Sudden unexpected death in epilepsy (SUDEP) is a sudden, unexpected death in people with epilepsy, with or without evidence of an epileptic seizure. The pathophysiological mechanism underlying SUDEP appears to be partly associated with an autonomic nervous system (ANS) dysfunction. Heart rate variability (HRV) analysis is a reliable, non-invasive method for detecting fluctuations in the ANS. In this systematic review we analyzed the data available in the literature on changes in HRV parameters in patients with SUDEP. We carried out a systematic search of the literature to identify the quantitative variations of HRV in epileptic patients with SUDEP. The following databases were used: Pubmed, Google Scholar, EMBASE, and CrossRef. A pooled analysis was carried out, and the results obtained were compared using mean difference (MD). The review was registered on the PROSPERO platform (CRD42021291586). Seven articles were included, with a total of 72 SUDEP cases associated with altered HRV parameters. Generally, a reduction of SDNN (standard deviation of the RR intervals) and RMSSD (root mean square differences of successive RR intervals) was reported in most SUDEP patients. According to MD, the SUDEP patients showed no differences in time and frequency domain parameters compared to controls. However, a trend toward increased low frequency and high frequency ratio (LF/HF) was observed in the SUDEP patients. HRV analysis is a valuable method for assessing cardiovascular risk and cardioautonomic impairment. Although a possible association between HRV variation and SUDEP has been reported, further studies are needed to assess the potential role of HRV modifications as a SUDEP biomarker.

Heart rate variability in people with metabolic syndrome

Metabolic syndrome (MS) is characterized by disorders of carbohydrate and fat metabolism, which can lead to the development of cardiac autonomic neuropathy (CAN). Heart rate variability (HRV) analysis is used to assess the state of autonomic regulation. A decrease in HRV indicates unfavourable changes in autonomic regulation and the development of CAN. The purpose of this study was to compare HRV parameters in patients with metabolic syndrome and healthy individuals without signs of MS. We examined 74 patients with metabolic syndrome (mean age 54.4 ± 1.1 years) and 61 healthy subjects (without signs of MS) (mean age 57.0 ± 1.6 years). The results of the study indicate a significant decrease in HRV in people with MS. However, they had significantly lower values of the SDNN index (by 26%), which characterizes the overall power of neurohumoral regulation of heart rate. Differences in the indicators characterizing short-term, vagal influences were especially pronounced: in patients with MS, RMSSD (by 44%) and HF (by 69%) were lower than in controls. The activity of the baroreflex center of the medulla oblongata, assessed by the spectral power of low-frequency waves (LF), was 55% lower in patients with MS compared to controls. There were no significant differences in the mean duration of the R-R interval, the spectral power of very low frequency (VLF) waves, or the ratio of the spectral powers of low and high frequencies (LF/HF, LFn, HFn) in patients with MS compared to controls. No significant shift in the autonomic balance towards sympathicotonia was found in patients with MS. The analysis of variance confirmed the significant effect of the metabolic syndrome factor on HRV. Thus, the data obtained indicate the development of CAN in people with metabolic syndrome, which is an unfavourable prognostic sign. To assess the effect of MS on the rate of ageing, the biological age (BA) of the examined people with MS was calculated. The formula for calculating BA was obtained on a group of people without MS. The method of multiple stepwise regression was used. The ageing rate was calculated as the difference between biological and chronological age (CA). The average BA in the group of people with MS was 63,20 ± 1,81 years, and in the control group – 53.99 ± 1.71 years (p&lt; 0.05). The difference between BA and CA is 8,81 ± 0,94 years in the group of people with MS and -1.01 ± 0.61 in the control group (p&lt; 0.05). From this we can conclude that MS can be a factor accelerating ageing. _________________________________________________________________________________________ Keywords: metabolic syndrome, heart rate variability, biological age

Heart rate variability in people with metabolic syndrome

Metabolic syndrome (MS) is characterized by disorders of carbohydrate and fat metabolism, which can lead to the development of cardiac autonomic neuropathy (CAN). Heart rate variability (HRV) analysis is used to assess the state of autonomic regulation. A decrease in HRV indicates unfavourable changes in autonomic regulation and the development of CAN. The purpose of this study was to compare HRV parameters in patients with metabolic syndrome and healthy individuals without signs of MS. We examined 74 patients with metabolic syndrome (mean age 54.4 ± 1.1 years) and 61 healthy subjects (without signs of MS) (mean age 57.0 ± 1.6 years). The results of the study indicate a significant decrease in HRV in people with MS. However, they had significantly lower values of the SDNN index (by 26%), which characterizes the overall power of neurohumoral regulation of heart rate. Differences in the indicators characterizing short-term, vagal influences were especially pronounced: in patients with MS, RMSSD (by 44%) and HF (by 69%) were lower than in controls. The activity of the baroreflex center of the medulla oblongata, assessed by the spectral power of low-frequency waves (LF), was 55% lower in patients with MS compared to controls. There were no significant differences in the mean duration of the R-R interval, the spectral power of very low frequency (VLF) waves, or the ratio of the spectral powers of low and high frequencies (LF/HF, LFn, HFn) in patients with MS compared to controls. No significant shift in the autonomic balance towards sympathicotonia was found in patients with MS. The analysis of variance confirmed the significant effect of the metabolic syndrome factor on HRV. Thus, the data obtained indicate the development of CAN in people with metabolic syndrome, which is an unfavourable prognostic sign. To assess the effect of MS on the rate of aging, the biological age (BA) of the examined people with MS was calculated. The formula for calculating BA was obtained on a group of people without MS. The method of multiple stepwise regression was used. The aging rate was calculated as the difference between biological and chronological age (CA). The average BA in the group of people with MS was 63,20 ± 1,81 years, in the control group – 53.99 ± 1.71 years (p&lt; 0.05). The difference between BA and CA is 8,81 ± 0,94 years in the group of people with MS and -1.01 ± 0.61 in control group (p&lt; 0.05). From this we can conclude that MS can be a factor accelerating aging. _________________________________________________________________________________________ Keywords: metabolic syndrome, heart rate variability, biological age

Heart rate variability is associated with disease severity and portal hypertension in cirrhosis.

Autonomic nervous system activity in cirrhotic portal hypertension is linked to hyperdynamic circulation. Heart rate variability (HRV) is a validated noninvasive method to assess the sympathovagal balance. To investigate the correlation between HRV parameters and degree of portal hypertension, we studied a cohort of patients with cirrhosis accounting for etiology and treatments. In this cross-sectional, observational cohort study, 157 outpatients of both sex with nonalcoholic cirrhosis were assessed by upper gastrointestinal endoscopy to search for esophagogastric varices. Twenty-four-hour electrocardiogram Holter monitoring with 3 HRV parameters measurement [SD of the NN intervals, root mean square successive difference of NN intervals, and SD of the averages of NN intervals (SDANN)] according to time-domain analysis were performed in all patients. Sixteen patients with large esophagogastric varices underwent measurements of the HVPG and assessment of HRV parameters at baseline and after 45 days on carvedilol. The liver dysfunction, expressed by Child-Pugh class or MELD score, was directly related to root mean square successive difference of NN intervals and inversely related to SDANN. Presence of ascites was inversely related to SDANN and to SD of the NN intervals. Treatment with carvedilol had an inverse relation with SDANN. Presence and size of esophagogastric varices had an inverse relation to SDANN and SD of the NN intervals. Upon multivariate analysis the associations between SDANN and Child-Pugh class, size of varices and ascites were confirmed. In the subgroup of 16 patients undergoing HVPG measurement, pressure gradient was unrelated to heart rate and HRV parameters. Time-domain HRV parameters in patients with cirrhosis, confirm the autonomic nervous system alteration, and their correlation to the degree of portal hypertension suggesting a role of the ANS in hepatic decompensation.

Evaluation of heart rate variability in patients with different forms of pulmonary hypertension

Pulmonary hypertension (PH) is a severe pathology of the cardiovascular system with extremely poor prognosis, if unreated. Early diagnosis of PH is difficult, due to the absence pathognomonic symptoms, and at the initial stage the disease may be asymptomatic. An increase in pulmonary vascular resistance and pressure in the pulmonary artery cause severe dysfunction of the right ventricle, which affects the functional status of patients. The assessment of heart rate variability (HRV) parameters is used to predict the increased risk of sudden death in various diseases of the cardiovascular system and the functional status of the body. HRV is mainly regulated by the sympathetic and parasympathetic divisions of the autonomic nervous system. It is noted that pulmonary arterial hypertension is associated with increasing of sympathetic activity. The review, based on the analysis of the pathophysiological mechanisms of pulmonary arterial hypertension and chronic thromboembolic PH, presents the results of studies assessing the time and spectral parameters of HRV in patients with PH of various etiologies.

Heart rate variability in patients with refractory epilepsy: The influence of generalized convulsive seizures

ObjectivePatients with epilepsy, mainly drug-resistant, have reduced heart rate variability (HRV), linked to an increased risk of sudden death in various other diseases. In this context, it could play a role in SUDEP. Generalized convulsive seizures (GCS) are one of the most consensual risk factors for SUDEP. Our objective was to assess the influence of GCS in HRV parameters in patients with drug-resistant epilepsy. MethodsWe prospectively evaluated 121 patients with refractory epilepsy admitted to our Epilepsy Monitoring Unit. All patients underwent a 48-hour Holter recording. Only patients with GCS were included (n = 23), and we selected the first as the index seizure. We evaluated HRV (AVNN, SDNN, RMSSD, pNN50, LF, HF, and LF/HF) in 5-min epochs (diurnal and nocturnal baselines; preictal – 5 min before the seizure; ictal; postictal – 5 min after the seizure; and late postictal – >5 h after the seizure). These data were also compared with normative values from a healthy population (controlling for age and gender). ResultsWe included 23 patients, with a median age of 36 (min-max, 16–55) years and 65% were female. Thirty percent had cardiovascular risk factors, but no previously known cardiac disease. HRV parameters AVNN, RMSSD, pNN50, and HF were significantly lower in the diurnal than in the nocturnal baseline, whereas the opposite occurred with LF/HF and HR. Diurnal baseline parameters were inferior to the normative population values (which includes only diurnal values). We found significant differences in HRV parameters between the analyzed periods, especially during the postictal period. All parameters but LF/HF suffered a reduction in that period. LF/HF increased in that period but did not reach statistical significance. Visually, there was a tendency for a global reduction in our patients’ HRV parameters, namely AVNN, RMSSD, and pNN50, in each period, comparing with those from a normative healthy population. No significant differences were found in HRV between diurnal and nocturnal seizures, between temporal lobe and extra-temporal-lobe seizures, between seizures with and without postictal generalized EEG suppression, or between seizures of patients with and without cardiovascular risk factors. Significance/conclusionOur work reinforces the evidence of autonomic cardiac dysfunction in patients with refractory epilepsy, at baseline and mainly in the postictal phase of a GCS. Those changes may have a role in some SUDEP cases. By identifying patients with worse autonomic cardiac function, HRV could fill the gap of a lacking SUDEP risk biomarker.

РОЛЬ ЭСТРОГЕНОВ В ВЕГЕТАТИВНОЙ РЕГУЛЯЦИИ СЕРДЕЧНО-СОСУДИСТОЙ СИСТЕМЫ В МЕНОПАУЗЕ

Hot flashes are known to be associated with a variety of cardiovascular risk factors. There is evidence of a close relationship between hot flashes and autonomic dysfunction, while the parameter - heart rate variability (HRV) - is a surrogate marker for assessing the activity of the autonomic nervous system (ANS). However, changes in HRV can be caused by both aging and hormonal changes. The purpose of this work is to consider the role of endogenous estrogens in the autonomic regulation of the cardiovascular system on the model of "acute estrogen deficiency" in cases of total oophorectomy and "partial estrogen deficiency" - in cases of hysterectomy with / without appendages. 44 women were included, mean age - 46.9 ± 2.2 years, whose HRV was assessed before surgery (1 week before surgery) and after (not less than 4 and not more than 5 weeks after surgery). According to the results obtained, there were no statistically significant changes in both temporal and spectral HRV parameters in patients after hysterectomy (p&gt; 0.05). On the contrary, patients with total oophorectomy in the postoperative period showed decreased HRV parameters characterizing the parasympathetic activity of the ANS, namely SDRR, rMSSD, pNN50, HF and the LF index, reflecting both sympathetic and parasympathetic effects on heart rate. Patients with total oophorectomy have a higher ratio of the sympatovagal LF / HF index; the work shows that this fact is most likely due to the predominance of sympathetic nervous influences induced by "acute" withdrawal of ovarian hormones due to the performed volume of surgery, and not as a result of surgery. as such, or its psychological consequences. Thus, according to the above-described results of the study, patients in cases of total oophorectomy showed a decrease in the parameters of vagal HRV in the direction of sympathetic dominance, which may cause an increase in cardiovascular risk.

A common variation in HCN1 is associated with heart rate variability in schizophrenia

BackgroundThere is growing evidence for a shared genetic basis between schizophrenia risk and cardiovascular disease. Reduced efferent vagal activity, indexed by reduced heart rate variability (HRV), has been consistently described in patients with schizophrenia and may potentially contribute to the increased cardiovascular risk in these patients. In this study, we tested the hypothesis whether the established schizophrenia risk variant HCN1 rs16902086 (A > G) is associated with reduced HRV. MethodsWe analyzed the risk status of HCN1 rs16902086 (AG/GG vs. AA genotype) in 83 unmedicated patients with schizophrenia and 96 healthy controls and investigated genotype-related impacts on various HRV parameters. ResultsWe observed significantly increased resting heart rates and a marked decrease of vagal modulation in our patient cohort. Strikingly, HCN1 rs16902086 (A > G) was associated with reduced HRV parameters in patients only. A trend towards more pronounced HRV deviations was observed in homozygous (GG) compared to heterozygous patients (AG). ConclusionWe present first evidence for a genetic risk factor that is associated with decreased vagal modulation in unmedicated patients with schizophrenia. Moreover, our findings suggest that HCN1 might be involved in reduced vagal modulation and possibly in increased cardiac mortality in schizophrenia patients. Thus, our data indicate that reduced vagal modulation might be an endophenotype of schizophrenia.

Reliability of ultra-short indices for autonomic dysfunction in dyslipidemia.

Dyslipidemia is associated with autonomic nervous system (ANS) dysfunction. Heart rate variability (HRV) is a powerful tool for evaluating the ANS and for cardiovascular risk stratification. Yet, the methodologies used are impractical in most clinical settings and therefore, are usually not applied. The current study aimed to evaluate the reliability of ultra-short HRV parameters, which are easily calculated from any standard ECG, as a practical method for ANS study, with a focus on patients with dyslipidemia. Fifty-nine volunteers with dyslipidemia underwent HRV study of parametric and power spectral indices according to accepted methods. Correlations were calculated between ultra-short HRV indices (five 1-min and five 10-s segments) and standard 5-min recordings. Correlations were found between 10-s and 1-min RMSSD and 5-min recordings (mean Pearson ρ correlation coefficients of 0.913 and 0.944, respectively, and mean concordance correlation coefficients of 0.855 and 0.938, respectively). Associations were found between other ultra-short HRV parameters (SDNN, maximum RR, minimum RR, pNN50, ln(RMSSD) and 5-min recordings. In addition, average RR, HRV-TI, NN50, TP, LF/HF, ln(SDNN), ln(HRV-TI), ln(TP) and ln(LF/HF) from 1-min recordings were associated with 5-min values. In conclusion, some ultra-short HRV parameters can be used for ANS evaluation and presumably, for cardiovascular risk stratification among patients with dyslipidemia. These parameters seem to be of great practical value for both inpatient and outpatient settings, because most can be calculated from a standard 10-s ECG strip. The prognostic implications of ECG-derived, ultra-short HRV parameters in patients with dyslipidemia should be further evaluated in future studies.

Impact of Elective Percutaneous Transluminal Coronary Angioplasty (PTCA) on Heart Rate Variability in Patients with Coronary Artery Disease

Coronary artery disease (CAD) is a major public health problem in India and is one of the leading causes of mortality and morbidity. Impairment of heart rate variability (HRV) has been observed in patients with CAD. Percutaneous transluminal coronary angioplasty (PTCA) is one of the common modalities of treatment of CAD. In this study we have studied the effect of successful elective PTCA on HRV parameters in patients with CAD. Material and Method: HRV parameters in both time and frequency domain were studied in 30 male patients before PTCA, one day and three day after PTCA. Results: - The time and frequency domain parameters between pre PTCA and 1st day post PTCA were not found to be statistically significant. Changes in the time domain parameter rMSSD and SDNN was statistically significant between pre and 3rd day post PTCA but no significant difference was observed in pNN50. A significant decrease in LF n.u and increase in HF n.u was observed between pre and 3rd day post PTCA. Conclusion: Revascularization with PTCA results in improvement of the autonomic tone. Improved autonomic modulation is seen as early as 3rd day post PTCA. It indicates that restoring the blood flow reverses to some extent the autonomic modulatory effect of coronary artery disease.

The analysis of circadian rhythm of heart rate variability in patients with drug-resistant epilepsy

ObjectiveThe aim of this study was to investigate the variations and the circadian rhythm of multi-domain parameters of heart rate variability (HRV) in patients with drug-resistant epilepsy. MethodsTime domain HRV parameters of 24-hour data, frequency and non-linear domain HRV parameters were calculated using a 24-hour ambulatory electrocardiogram (ECG) from subjects in a resting and awake state (5-min data from 9:00-10:00 a.m.). Circadian fluctuation (24 one-hour segments) and the night (00:00 - 05:00)/ day (07:30 - 09:30) ratio of each HRV parameter were measured in (i) refractory epilepsy (n = 51) and (ii) healthy, age and sex matched controls (n = 50). Cosinor fit method was used to quantify the pattern of the circadian rhythm of HRV. ResultsCompared to healthy controls, patients with drug-resistant epilepsy had significantly decreased time domain (mean_RR, STDRR, RMSSD, pNN50, HRV_triangular_index), frequency domain (VLF_power, LF_power, HF_power, Total_power) and non-linear domain (Poincaré SD1, SD2, D2) HRV measurements. There were also overall reductions in amplitude and the baseline of circadian curves of HRV parameter in the patients group, especially nocturnal inhibition of cardiac autonomic modulations was stronger than that in daytime. The majority of differences in HRV values between the two groups reached a maximum in early morning (usually 5:00 or 6:00 a.m.). No significant differences were found in the night/day ratios of multi-domain HRV measurements between patients and healthy controls (p = 0.862). ConclusionsThe significant suppression of HRV parameters in patients with refractory epilepsy may reflect the inhibitions of both sympathetic and parasympathetic activities. This is notably the first time that marked circadian diversity of HRV measurments between the patient and control groups were found and quantified by cosinor fit method. The difference in amplitude increased during night with peak occurrence between 5:00 or 6:00 a.m. These findings may be linked to cardiac autonomic dysfunction and subsequent sudden unexpected death in epilepsy (SUDEP), which is reported to often occur during night or early morning. Taken together, HRV parameters may be potential bio-markers for predicting SUDEP.

Autonomic Function in Insular Glioma: An Exploratory Study

Autonomic nervous system dysfunction is a known entity in strokes involving insula. It causes significant morbidity and mortality. No study to date has demonstrated autonomic nervous system dysfunction in patients with insular glioma. This is an exploratory study to identify the subclinical autonomic dysfunctions in insular glioma. A total 50 patients with newly diagnosed insular glioma in the age group of 18-60 years were evaluated with heart rate variability (HRV). All the HRV parameters in patients with insular glioma were compared with normal healthy age- and sex-matched control patients. There was a significant difference (P < 0.05) in most of the HRV parameters between patients and control patients. Patients with left insular glioma showed significantly increased heart rate (P= 0.027), low-frequency normalized units (P= 0.048), and also increased low-frequency/high-frequency ratio (P= 0.015), which indicates sympathetic dominance. Patients with seizures had significantly lower values of total power (P= 0.042). No significant difference was found in terms of the extent and size of the tumor or histopathologic grades of gliomas. Patients with insular gliomas have significant impairment of autonomic functions, with left insular glioma showing sympathetic dominance. Suppression of autonomic function is greater in those presenting with seizures.

Renal sympathetic denervation induces changes in heart rate variability and is associated with a lower sympathetic tone.

Renal nerve stimulation (RNS) is used to localize sympathetic nerve tissue for selective renal nerve sympathetic denervation (RDN). Examination of heart rate variability (HRV) provides a way to assess the state of the autonomic nervous system. The current study aimed to examine the acute changes in HRV caused by RNS before and after RDN. 30 patients with hypertension referred for RDN were included. RNS was performed under general anesthesia before and after RDN. Heart rate (HR) and blood pressure (BP) were continuously monitored. HRV characteristics were assessed 1min before and after RNS and RDN. RNS before RDN elicited a maximum increase in systolic BP of 45 (± 22)mmHg which was attenuated to 13 (± 12)mmHg (p < 0.001) after RDN. RNS before RDN decreased the sinus cycle length from 1210 (± 201) ms to 1170 (± 203) ms (p = 0.03), after RDN this effect was blunted (p = 0.59). The LF/HF ratio in response to RNS changed from ∆ + 0.448 (± 0.550) before RDN to ∆ - 0.656 (± 0.252) after RDN (p = 0.02). Selecting patients off beta-blockade (n = 11), the RNS-induced changes in HRV components before versus after RDN were more pronounced (LF/HF ratio ∆ + 0.900 ± 1.171 versus ∆ - 0.828 ± 0.519, p = 0.01), whereas changes in HRV parameters in patients on beta-blockade (n = 19) were no longer significant. In patients with diabetes mellitus (n = 7), RNS induced no changes in HRV parameters (LF/HF ratio ∆ - 0.039 ± 0.103 versus ∆ - 0.460 ± 0.491, p = 0.92). RNS induces changes in HRV suggesting increased sympathetic activity. Conversely, after RDN, the RNS-induced changes in HRV suggesting a lower sympathetic autonomic balance. These changes were most pronounced in beta-blocker naïve patients and not present in patients with diabetes mellitus. These findings could support RNS-guided RDN to optimize results.

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.

The effect of level of injury and physical activity on heart rate variability following spinal cord injury

Objective/Background: To assess frequency domain heart rate variability (HRV) parameters at rest and in response to postural autonomic provocations in individuals with spinal cord injury (SCI) and investigate the autonomic influences on the heart of different physical activities.Design: Cross-sectional study.Methods: Ten subjects with complete cervical SCI and fourteen subjects with complete low thoracic SCI were prospectively recruited from the community and further divided in sedentary and physically active groups, the latter defined as regular weekly 4 hour physical activity for the preceding 3 months. Sixteen healthy individuals matched for sex and age were recruited to participate in the control group. The Low Frequency (LF), High Frequency (HF) powers and the LF/HF ratio of HRV were measured from continuous electrocardiogram (ECG) recordings at rest and after sitting using a fast Fourier transformation.Outcome measures: The LF,HF, and the LF/HF ratio at rest and after sitting.Results: A significant decrease in all HRV parameters in patients with SCI was found compared to controls. The change in HF, LF and LF/HF following sitting maneuver was significantly greater in controls as compared with the SCI group and greater in subjects with paraplegia as compared to subjects with tetraplegia. Better HRV values and enhanced vagal activity appears to be related to the type of physical activity in active subjects with paraplegia.Conclusion: In this cohort of subjects spectral parameters of HRV were associated with the level of the injury. Passive standing was associated with higher HRV values in subjects with paraplegia.

STRUCTURAL AND FUNCTIONAL CHANGES EVALUATED BY ECHOCARDIOGRAPHY IN PATIENTS WITH SYSTEMIC SCLEROSIS AND HEART RATE VARIABILITY

Objective: to estimate heart rate variability (HRV) in patients with systemic sclerosis (SS) and to investigate their relationship to echocardiographic structural and functional changes in the heart. Subjects and methods. The investigation enrolled 125 patients with SS and 50 gender- and age-matched apparently healthy individuals who made up a control group. In addition to clinical examinations, 73 patients underwent HRV assessment from 24-hour Holter electrocardiogram (ECG) monitoring results and 121 patients had echocardiography (EchoCG). 24-hour Holter ECG monitoring was carried out in all control individuals. Results and discussion . Examination of the main parameters of time-domain HRV in patients with SS revealed a significant decline in all temporal and spectral indices, except for the mean R–R interval duration (meanNN), as compared with the control group. EchoCG detected a variety of changes, primarily the induration and calcification of aortic and mitral valves in most patients. Left ventricular diastolic dysfunction was encountered in almost half of the patients with SS. Eight patients had a lower left ventricular ejection fraction (LVEF), which was <55%. Studying the association of HRV values with separate EchoCG parameters revealed significant inverse correlations of the mean standard deviation of R–R intervals in 5-minute recording segments during 24 hours with the thickness of the interventricular septum (r = -0.18; p < 0.05) and with the induration of the aortic valve (r = -0.18; p < 0.05); the square root mean squared of successive differences (RMSSD, ms) for R–R intervals and the percentage of adjacent R–R intervals that varied by more than 50 ms (pNN50) correlated with the induration of the aortic valve (r = -0.23; p<0.05 and r = -0.25; p < 0.05, respectively), with the presence of pericarditis (r = -0.24; p < 0.05 and r = -0,27; p < 0.05, respectively), and with the level of pulmonary artery systolic pressure (r = -0.23; p < 0.05 and r = -0.27; p < 0.05, respectively). There was also a direct correlation of rMSSD and pNN50 with LVEF (r = 0.27; p < 0.05 and r = 0.29, respectively; p < 0.05). A significant decrease in rMSSD and pNN50 was ascertained in hypertensive patients as compared to non-hypertensive patients (18.1±4.8 and 24.9±13.3; 2.3±1.8 and 5.7±6.5, respectively; p < 0.05). Conclusion. Comprehensive examination using EchoCG and 24-hour Holter ECG monitoring revealed the high frequency and severity of significant cardiac changes in SS. The temporal spectrum analysis of HRV could confirm a significant reduction in the function of both the sympathetic and parasympathetic parts of the autonomic nervous system. Decreased HRV was associated with SS severity and activity, traditional cardiovascular risk factors, and cardiac structural changes.

Effects of Mental Stress Induction on Heart Rate Variability in Patients with Panic Disorder.

Reduced heart rate variability (HRV) constitutes a widely used marker of cardiac autonomic inflexibility which has been linked to disorders such as panic disorder (PD). To date, the pathophysiological mechanisms whereby panic leads to attenuated HRV are not fully elucidated. We aimed to investigate the hypothesis that PD patients show pathological reactivity both in response to interoceptive and psychosocial stress in comparison to healthy individuals. We performed a controlled study on 38 patients diagnosed with PD [20 males and 18 females aged 35.55±10.12years, mean±standard deviation] and 23 age and gender matched healthy control participants. Distress was induced using the Trier Social Stress Test (TSST) and the dexamethasone-corticotropin-releasing-hormone (DEX-CRH) test. We assessed HRV prior to, during, and post-stress induction using the root mean square successive differences (RMSSD) as well as spectral analysis (high frequency; HF and low frequency; LF). Statistical analyses revealed significant main effects of time for mean heart rate (HR), HF, LF (solely DEX-CRH), LFHF-ratio (solely TSST) and the RMSSD. Significant interaction effects were observed with more pronounced increases in mean HR (TSST) and LFHF-ratio (DEX-CRH) in the healthy control participants. No significant main effects of group were observed. Overall, our results indicate "normal" HRV parameters in patients with PD. The HRV of PD patients is no worse than that of healthy control participants since the HRV profiles were similar between the study groups. The current study is one of rather rarely published studies which was unable to show an influence of PD on HRV. Implications for future studies are under discussion.