Spectral Analysis Of Heart Rate Variability Research Articles

Pulse transit time and heart rate variability in sleep staging.

This paper presents a new and robust algorithm for detection of sleep stages by using the lead I of the Electrocardiography (ECG) and a fingertip Photoplethysmography (PPG) sensor, validated using multiple overnight PSG recordings consisting of 20 human subjects (9 insomniac and 11 healthy). Heart Rate Variability (HRV) and Pulse Transit Time (PTT) biomarkers which were extracted from ECG and PPG biosignals then employed to extract features. Distance Weighted k-Nearest Neighbours (DWk-NN) was used as classifier to differentiate sleep epochs. The validation of the algorithm was evaluated by Leave-One-Out-Cross-Validation method. The average accuracy of 73.4% with standard deviation of 6.4 was achieved while the algorithm could distinguish stages 2, 3 of non-rapid eye movement sleep by average sensitivity of almost 80%. The lowest mean sensitivity of 53% was for stage 1. These results demonstrate that an algorithm based on PTT and HRV spectral analysis is able to classify and distinguish sleep stages with high accuracy and sensitivity. In addition the proposed algorithm is capable to be improved and implemented as a wearable, comfortable and cheap instrument for sleep screening.

Effect of dancing and nutrition education on hemodynamic and autonomic status in adults with metabolic syndrome: a randomized controlled clinical trial

BackgroundAlthough the benefits of exercise and changes in lifestyle on components of the metabolic syndrome (MS) have been described, little is known about the effect of dancing and nutritional changes on the cardiovascular system. ObjectiveEvaluate the effect of an intervention based on dancing and nutrition education on hemodynamic and autonomic status in adults with MS. MethodsA randomized controlled clinical trial was conducted involving 59 adults with MS. The intervention lasted 12 weeks and consisted of an aerobic exercise program (dancing) at an intensity of 60-75% of heart rate reserve, 60minutes 3 times a week, and muscle strength training at an intensity of 50% of a maximum repetition, 30minutes twice a week. The nutrition education program consisted of 2-hour workshops each week. Assessment of impedance cardiography and function of nervous system with analysis of heart rate variability (HRV) were made before and after the intervention. ResultsIn the intervention group, a decrease in mean arterial pressure of -7.8mmHg (95% CI, -12.84 to -2.75; P=0.004) was found as well as in the systemic vascular resistance (SVR) index of -864.29 dyn·s·m2/cm5 (95% CI, -1506.31 to -222.26; P=0.010). Increase was observed in the cardiac output index of 0.48 L/min/m2 (95% CI, 0.14 to 0.83; P=0.007). In the spectral analysis of HRV a reduction in LF/HF ratio of -0.52 (95% CI, -1.02 to -0.02; P=0.040) was also found. ConclusionsAn intervention with dancing and nutrition education lowers arterial blood pressure and SVR and has favorable effects on the sympathovagal balance in patients with MS.

Spectral Heart Rate Variability analysis using the heart timing signal for the screening of the Sleep Apnea–Hypopnea Syndrome

Some approaches have been published in the past using Heart Rate Variability (HRV) spectral features for the screening of Sleep Apnea–Hypopnea Syndrome (SAHS) patients. However there is a big variability among these methods regarding the selection of the source signal and the specific spectral components relevant to the analysis. In this study we investigate the use of the Heart Timing (HT) as the source signal in comparison to the classical approaches of Heart Rate (HR) and Heart Period (HP). This signal has the theoretical advantage of being optimal under the Integral Pulse Frequency Modulation (IPFM) model assumption. Only spectral bands defined as standard for the study of HRV are considered, and for each method the so-called LF/HF and VLFn features are derived. A comparative statistical analysis between the different resulting methods is performed, and subject classification is investigated by means of ROC analysis and a Naïve-Bayes classifier. The standard Apnea-ECG database is used for validation purposes. Our results show statistical differences between SAHS patients and controls for all the derived features. In the subject classification task the best performance in the testing set was obtained using the LF/HF ratio derived from the HR signal (Area under ROC curve=0.88). Only slight differences are obtained due to the effect of changing the source signal. The impact of using the HT signal in this domain is therefore limited, and has not shown relevant differences with respect to the use of the classical approaches of HR or HP.

Comparison between Fast Fourier Transform and Autoregressive Model on Analysis of Autonomic Nervous Function after Food Intake in Women

Purpose: Heart rate variability (HRV) is acknowledged as a useful tool to estimate autonomic function. Fast Fourier transform (FFT) and autoregressive model (AR) are used for power spectral analysis of HRV. However, there is little evidence of agreement between FFT and AR in relation to HRV following food intake in females. In the present study, we applied both FFT and AR after food intake during the follicular and luteal phases, and compared raw low-frequency (LF) and high- frequency (HF) powers, and LF/HF ratio obtained with the two power-spectral analytical methods. Methods: All subjects participated in two sessions: follicular phase session and luteal phase session. In each session, R-R intervals were continuously recorded before and after meals, and power spectral analysis of heart rate variability was performed. We analyzed low-frequency power (LF: 0.04 - 0.15 Hz) and high-frequency power (HF: 0.15 - 0.40 Hz) by using FFT and AR. LF and HF power were computed for each 30 sec, 1 min, 2.5 min, and 5 min of the 5-min R-R data before meal intake and at 20, 40, 60 and 80 min after meal intake. The LF/HF ratio was calculated as an index of sympathovagal balance. Results: In the present study, after 30 sec and 1 min of segment analysis, there was little interchangeability between AR and FFT in LF, HF, and LF/HF ratio in both follicular and luteal phases. In 2.5 min or 5 min of segment analysis, there was interchangeability between FFT and AR in LF and HF, but not in the LF/HF ratio in both follicular and luteal phases. Additionally, FFT underestimated HRV compared with AR, and the extent of underestimation increased with increasing AR value. Conclusion: FFT underestimated HRV compared with AR, and FFT correlated poorly with AR when the analysis segment was shortened.

Power spectral analysis of cardiovascular autonomic functional modulation in response to acute mental stress in polycystic ovarian syndrome—an observational study

Background: Patients with polycystic ovary syndrome (PCOS) can experience cardiac autonomic dysfunction. Heart rate variability (HRV) is used in assessing cardiac autonomic functions. Aims and Objective: To evaluate cardiovascular autonomic functional modulation by using HRV during rest and acute mental stress in female subjects with PCOS. Materials and Methods: Thirty patients with PCOS (mean age 27.13 ± 4.53 years) and 30 healthy female volunteers who were matched for body mass index and age (mean age 25.87 ± 6.54 years) were enrolled in the study. The study was conducted during the follicular phase for control subjects and in amenorrheic phase for subjects with PCOS. Frequency-domain power spectral analysis of HRV was carried out using nonparametric method of fast Fourier transform using Kubios HRV analysis software. Mental stress was induced by arithmetic mental challenge under time pressure. Result: On comparison with the control subjects, female subjects with PCOS demonstrated a significant reduction in total power of HRV and high frequency (Hf) during rest (p = 0.016) (p = 0.00) and significant increase in low frequency (Lf) (p = 0.0134) and Lf/Hf ratio (p = 0.000). There is significant reduction in total power of HRV, Hf (nu), and Lf/Hf ratio during stress in subjects with PCOS when compared with control subjects. Conclusion: We conclude that female subjects with PCOS exhibit altered cardiac autonomic modulation during rest in terms of decreased parasympathetic tone and increased sympathetic tone. They also show failure to cope up to mental stresses as shown by insufficient sympathetic response to stress.

Monitoring Fatigue Status with HRV Measures in Elite Athletes: An Avenue Beyond RMSSD?

Among the tools proposed to assess the athlete's “fatigue,” the analysis of heart rate variability (HRV) provides an indirect evaluation of the settings of autonomic control of heart activity. HRV analysis is performed through assessment of time-domain indices, the square root of the mean of the sum of the squares of differences between adjacent normal R-R intervals (RMSSD) measured during short (5 min) recordings in supine position upon awakening in the morning and particularly the logarithm of RMSSD (LnRMSSD) has been proposed as the most useful resting HRV indicator. However, if RMSSD can help the practitioner to identify a global “fatigue” level, it does not allow discriminating different types of fatigue. Recent results using spectral HRV analysis highlighted firstly that HRV profiles assessed in supine and standing positions are independent and complementary; and secondly that using these postural profiles allows the clustering of distinct sub-categories of “fatigue.” Since, cardiovascular control settings are different in standing and lying posture, using the HRV figures of both postures to cluster fatigue state embeds information on the dynamics of control responses. Such, HRV spectral analysis appears more sensitive and enlightening than time-domain HRV indices. The wealthier information provided by this spectral analysis should improve the monitoring of the adaptive training-recovery process in athletes.

Predicting the outcome of head-up tilt test using heart rate variability and baroreflex sensitivity parameters in patients with vasovagal syncope.

The aim of the study was to investigate whether a statistical model could be used for an early prediction of the head-up tilt test (HUTT) outcome from heart rate variability (HRV) and baroreflex sensitivity (BRS) data obtained during early stages of the HUTT. A modified Italian protocol was used for HUTT in 105 patients with a previous history of vasovagal syncope. Beat-to-beat heart rate and blood pressure were continuously recorded. Fast Fourier transformation was used for spectral analysis of HRV and a sequence technique for measuring the BRS. Linear statistical models based on HRV and BRS data from the first 15 min of HUTT were no more accurate than always naively predicted majority class that a syncope will occur (average model out-of-sample accuracy 56.2 ± 5.1 % vs. majority class relative frequency 54.2 %). Even when HRV and BRS data from the first 30 min were used in the model, we did not obtain any predictions of meaningful practical value (75.0 ± 5.1 % accuracy vs. 72.2 % majority class). While there are discernible and meaningful differences between HUTT-P and HUTT-N subjects, they are not sufficient to discriminate between the two groups and predict a syncope early in the HUTT. The results might improve with a larger set of subjects; however, we can conclude that it is not likely that syncope predictions of practical value can be obtained from aggregate HRV spectral analysis and BRS values.

Параметры спектрального анализа вариабельности сердечного ритма у крыс

The paper considers the synthesis and analysis of the reported data on the use of the parameters of spectral analysis when studying the heart rate variability (HRV) in rats. There were demonstrated the criteria for electrocardiographic equipment to perform studies in small mammals, substantiated the indices of duration of electrocardiogram (ECG) recording and indicated the necessity in stationary state of animals during ECG recording. When describing the ranges of spectral frequencies and data-based reports we suggested the parameters of HRV spectral analysis during 5-minute ECG recording in conscious rats such as: TP – 0.015–3 Hz; VLF – 0.015–0.04 Hz; LF – 0.05–0.79 Hz; HF – 0.8–3 Hz. The paper pointed to the need of performing extra-studies on the Mayer wave frequency, as well as the expediency of HRV spectral analysis together with respiration diagram recording. To clarify the parameters of spectral frequencies we recommended the findings comparing with the results of other research methods of HRV. The data of statistical processing of cardiointervalograms during ECG recording in unrestrained rats will enable to specify the selected parameters, accept a common protocol of HRV spectral analysis in this animal species and evaluate their vegetative status. Probl Cryobiol Cryomed 2015; 25(3):235-245.

Cardiac autonomic dysfunction in patients with gastroesophageal reflux disease.

To investigate autonomic nervous function in patients with a diagnosis of gastroesophageal reflux disease (GERD). The investigation was performed on 29 patients (14 men), aged 18-80 years (51.14 ± 18.34), who were referred to our Neurocardiology Laboratory at the Clinical and Hospital Center "Bezanijska Kosa" with a diagnosis of GERD. One hundred sixteen healthy volunteers matched in age and sex with the examinees served as the control group. The study protocol included the evaluation of autonomic function and hemodynamic status, short-term heart rate variability (HRV) analysis, 24 h ambulatory ECG monitoring with long-term HRV analysis and 24 h ambulatory blood pressure monitoring. Pathologic results of cardiovascular reflex test were more common among patients with reflux compared to the control group. Severe autonomic dysfunction was detected in 44.4% of patients and in 7.9% of controls (P < 0.001). Parameters of short-term analysis of RR variability, which are the indicators of vagal activity, had lower values in patients with GERD than in the control group. Long-term HRV analysis of time-domain parameters indicated lower values in patients with reflux disease when compared to the control group. Power spectral analysis of long-term HRV revealed lower low- and high-frequency values. Detailed 24 h ambulatory blood pressure analysis showed significantly higher values of systolic blood pressure and pulse pressure in the reflux group than in the control group. Patients with GERD have distortion of sympathetic and parasympathetic components of the autonomic nervous system, but impaired parasympathetic function appears more congruent to GERD.

PP.34.31

Objective: To correlate cognitive performance with heart rate variability (HRV) in elderly normotensives and hypertensives. Design and method: Global cognition was assessed by CAMCOG-R summation score in elderly normotensives [NTN; n = 20 (7 women); 68 ± 1yo; 131 ± 3mmHg; 66 ± 2bpm; education = 11 ± 1y] and hypertensives [HTN; n = 42 (26 women); 68 ± 1yo; 149 ± 3mmHg; 68 ± 2bpm; education = 8 ± 1y]. Executive function (EF) was assessed by an EF score (EFS) derived from CAMCOG-R and WAIS-III. The domains in these tests that showed a correlation coefficient > 0.4 and p-value < 0.01 with the EF domain of CAMCOG-R were added to create the EFS. Thus, the EFS was the arithmetic sum of EF, language expression, verbal fluency, remote memory, learning, attention, praxis and perception domains in CAMCOG-R, and the raw scores of digits, comprehension, vocabulary, codes and symbols domains in WAIS-III. Depression was assessed by Beck Depression Inventory. We continuously measured supine HR for 15 min and during a 30-min head-up tilt with Finometer. Supine (S) and orthostatic (O) autonomic modulation of HR was assessed through the ratio of spectral analysis of HRV in the low and high frequency (LF/HF) bands. The LF/HR is a non-dimensional index of the balance between the sympathetic and parasympathetic output to the heart. Results: The CAMCOG-R summation score and EFS were greater in NTN (87 ± 2 vs. 77 ± 1, p < 0.001 and 237 ± 6 vs. 189 ± 7, p < 0.001), respectively. Supine LF/HF were similar in NTN and HTN (1.5 ± 0.2 vs. 1.4 ± 0.2, p = 0.8) whereas O-LF/HF was greater in NTN (2.5 ± 0.5 vs. 1.5 ± 0.2, p = 0.04). In linear multivariable regression models controlled for sex and depression, hypertension and less education were independent adverse predictors of CAMCOG-R summation score and EFS whereas a lower O-LF/HF was an adverse predictor of EFS (Table). Conclusions: Normotensives exhibited better global cognition and executive function than hypertensives. In line with literature, we showed that both hypertension and less education are associated with lower global cognition and executive function. Notably, altered O-LF/HF does not impact global cognition but may impair executive function. Our results suggest that autonomic modulation of HR is not correlated with global cognition but may modulate executive function in elderly hypertensives.

Chronic dopaminergic treatment in restless legs syndrome: does it affect the autonomic nervous system?

ObjectiveThe link between the autonomic nervous system and restless legs syndrome (RLS) has been recently postulated. Since dopaminergic agents are used as first-line treatment for RLS, the purpose of our study is to verify whether chronic pramipexole treatment could influence the autonomic control of cardiovascular reflexes and heart rate variability (HRV) in RLS during wakefulness. MethodsConsecutive drug naive RLS patients underwent polysomnography (PSG), subjective scales, and cardiovascular function tests including head-up tilt test (HUTT), Valsalva maneuver, deep breathing, handgrip and cold face before and after 3-month pramipexole therapy. HRV analysis was performed in the frequency domain using both autoregressive and fast Fourier transform algorithms in rest supine condition and during HUTT. ResultsTwenty RLS patients reported a significant reduction of RLS symptoms after pramipexole treatment, while PSG did not show significant improvements except for periodic limb movement index. Pramipexole induced a trend to a lower systolic blood pressure and a significant higher variation of systolic and diastolic blood pressure at HUTT. Cardiovascular responses to the other tests were unchanged. No significant differences in HRV spectral analysis between drug naive and treated patients were observed. Moreover, the within-group analysis of HRV between orthostatic and supine position did not show any significant change in sympathetic and parasympathetic components both in the drug naive and pramipexole groups. ConclusionsChronic pramipexole treatment does not seem to affect autonomic balance during wakefulness. Considering that neither PSG data nor autonomic parameters are significantly modified by pramipexole, we hypothesize a non-dopaminergic autonomic dysfunction in RLS.

To Start Endurance Training After 40

It is unknown whether endurance training started earlier or later in life can reverse the deleterious effects of sedentary behaviour on the cardiovascular system. It could be that long-term endurance training have beneficial effects when started in the youth. But the benefits could be blunted in case of a later onset of training, when aging effects have already altered cardiovascular functions. PURPOSE: To evaluate if the age at which endurance training has been started modify cardiac and vascular parameters in healthy senior men. METHODS: We compared 40 asymptomatic men (55-70 years old) without any known cardiovascular risk factor: 10 have never practiced more than 2 hours of training per week during their lives (NT, 59±3 years old), and 30 trained in endurance (cycling or running) >5 hours a week. Among these athletes, 16 started the training before 30 (T30, 62±3 years old, 40.8±5.0 years of training) and 14 started the training after 40 (T40, 63±4 years old, 18.2±6.1 years of training). Maximal exercise test, echocardiography at rest and during submaximal exercise, and heart rate (HR) variability spectral analysis during 5 min supine were performed. RESULTS: First, three parameters of cardiovascular health differed between NT and both trained groups, without any difference between T30 and T40: resting HR (69.7±9.3, 56.8±10.0, and 58.1±4.9 bpm, respectively, p<0.05), maximal oxygen uptake (33.0± 4.3, 47.3±7.1, and 44.6±4.3 ml/min/kg, respectively, p<0.001), and resting autonomic balance (LF/HF; 4.1±3.1, 2.1± 1.4, and 2.0±0.7, respectively, p<0.05). Second, echocardiographic parameters of myocardial systolic and diastolic functions did not differ between the three groups. Third, during submaximal exercise (HR=110 bpm), indices of ventriculo-arterial coupling (p<0.01) and vascular functions (p<0.05) differed only between NT and T30: effective arterial elastance (2.4±0.6 vs. 1.7±0.5 mmHg/ml), left ventricular end-systolic elastance (6.8±1.9 vs. 4.4±1.5 mmHg/ml), valvulo-arterial impedance (1.4±0.3 vs. 1.1±0.4 mmHg/ml/m2), total arterial compliance (0.8±0.3 vs. 1.2±0.4 ml/mmHg), and total peripheral resistance (0.9±0.2 vs. 0.7±0.2 mmHg s/ml). CONCLUSIONS: According to our results, it seems that forty years old is not too late to start endurance training in order to improve cardiac health later in life. However, vascular functions seem to be more improved when endurance training is started earlier in life.

Heart rate variability and arterial oxygen saturation response during extreme normobaric hypoxia

The primary purpose of this study was to assess the response of autonomic cardiac activity and changes in the arterial oxygen saturation (SpO2) during normobaric hypoxia and subsequent recovery. Heart rate variability (HRV) and SpO2 were monitored in a supine position during hypoxia (FiO2=9.6%) for 10min, and normoxic recovery in 29 subjects. Spectral analysis of HRV quantified the autonomic cardiac activity by means of low frequency (LF) (0.05-0.15Hz) and high frequency (HF) (0.15-0.50Hz) power transformed by natural logarithm (Ln). Based on the SpO2 response to hypoxia, the subjects were divided into Resistant (RG, SpO2=80.8±7.0%) or Sensitive (SG, SpO2=67.2±2.9%) group. The SpO2 and vagal activity (LnHF) significantly decreased during hypoxia in both groups. A withdrawal in vagal activity was significantly greater in SG compared to RG. Moreover, only in SG, a relative increase in sympathetic modulation (Ln LF/HF) during hypoxia occurred. Correlations (r=-0.461, and r=0.595, both P<0.05) between ΔSpO2 (delta) and ΔLn LF/HF, and ΔLnHF were found. Based on results, it seems that SpO2 level could be an important factor that influences the autonomic cardiac response in hypoxia.

Cardiovascular neural regulation is impaired in amyotrophic lateral sclerosis patients. A study by spectral and complexity analysis of cardiovascular oscillations

Although the clinical hallmark of amyotrophic lateral sclerosis (ALS) is a progressive motor weakness, different combinations of autonomic nervous system (ANS) dysfunction have been described. No clear correlation between ANS abnormalities and ALS clinical characteristics has been found so far. We investigated the cardiovascular neural regulation in ALS with a non-invasive methodology, using spectral and complexity analysis of heart rate variability (HRV) and systolic arterial pressure (SAP) variability. In all patients, we found low RR variance and an altered response to orthostasis, witnessed by the indices derived from both spectral and complexity analysis of HRV and SAP variability. Besides, we identified two groups with distinct autonomic profiles at rest, those with higher, and those with lower cardiac sympathetic activity. In both groups the cardiovascular response to tilting was impaired. Our study outlined that ANS is invariably impaired in ALS, and patients can present with different baseline patterns. Our findings suggest important pathophysiological, clinical and prognostic insights. The presence of different autonomic profiles at rest supports the new concept of ALS as a multisystem disorder with phenotypic heterogeneity. Our results are also relevant in clinical practice. They can help to improve patients’ management, and to identify prognostic factors.

Computer-aided diagnosis of diabetic subjects by heart rate variability signals using discrete wavelet transform method

Diabetes Mellitus (DM), a chronic lifelong condition, is characterized by increased blood sugar levels. As there is no cure for DM, the major focus lies on controlling the disease. Therefore, DM diagnosis and treatment is of great importance. The most common complications of DM include retinopathy, neuropathy, nephropathy and cardiomyopathy. Diabetes causes cardiovascular autonomic neuropathy that affects the Heart Rate Variability (HRV). Hence, in the absence of other causes, the HRV analysis can be used to diagnose diabetes. The present work aims at developing an automated system for classification of normal and diabetes classes by using the heart rate (HR) information extracted from the Electrocardiogram (ECG) signals. The spectral analysis of HRV recognizes patients with autonomic diabetic neuropathy, and gives an earlier diagnosis of impairment of the Autonomic Nervous System (ANS). Significant correlations with the impaired ANS are observed of the HRV spectral indices obtained by using the Discrete Wavelet Transform (DWT) method. Herein, in order to diagnose and detect DM automatically, we have performed DWT decomposition up to 5 levels, and extracted the energy, sample entropy, approximation entropy, kurtosis and skewness features at various detailed coefficient levels of the DWT. We have extracted relative wavelet energy and entropy features up to the 5th level of DWT coefficients extracted from HR signals. These features are ranked by using various ranking methods, namely, Bhattacharyya space algorithm, t-test, Wilcoxon test, Receiver Operating Curve (ROC) and entropy.The ranked features are then fed into different classifiers, that include Decision Tree (DT), K-Nearest Neighbor (KNN), Naïve Bayes (NBC) and Support Vector Machine (SVM). Our results have shown maximum diagnostic differentiation performance by using a minimum number of features. With our system, we have obtained an average accuracy of 92.02%, sensitivity of 92.59% and specificity of 91.46%, by using DT classifier with ten-fold cross validation.

6. Neurophysiological methods of autonomic nervous system testing in multiple sclerosis

Autonomic dysfunction (AD) is commonly seen in patients with multiple sclerosis (MS). The most common manifestations of AD in MS patients include bladder or bowel dysfunction, impairment of sexual performance, pupillomotor or sweating alterations and orthostatic hypotension. Furthermore, AD is supposed to be related to fatigue. The incidence and severity of the symptoms related to AD correlated with the degree of disability. The lifetime prevalence of autonomic impairment reaches up to 80 % in MS population. Besides medical history and validated questionnaires, neurophysiological testing of cardiovascular and sudomotor functions are most commonly used for evaluation of autonomic nervous system impairment in MS patients. Of the cardiovascular tests, analysis of heart-rate variability in the time- and frequency-domain has repeatedly been published as a suitable method for evaluation of cardiovascular autonomic nervous system status in MS patients (the latter being mainly represented by spectral analysis of heart-rate variability). Autonomic challenge manoeuvres (suited for activation of sympathetic or parasympathetic nervous system) are also frequently used for this purpose and comprise Valsalva manoeuvre, deep metronomic breathing, response to active standing, sustained handgrip test, cold pressor test or cold face test. Furthermore, orthostatic challenge testing represented by head-up tilting (besides above mentioned active standing) can be useful in MS patients. Sudomotor functions in MS are most frequently tested using the sympathetic skin response (mainly because of wide availability of testing equipment), which seems to be less sensitive comparing cardiovascular tests. The availability of other testing methods, which may be used for the sweating evaluation (thermoregulatory sweat test, quantitative sudomotor axon reflex or similar tests) is lower, but they seem to have higher sensitivity in evaluation of sudomotor dysfunction in multiple sclerosis.

Cardiac autonomic modulation in healthy elderly after different intensities of dynamic exercise.

PurposeTo investigate the heart rate (HR) and its autonomic modulation at baseline and during dynamic postexercise (PEX) with intensities of 40% and 60% of the maximum HR in healthy elderly.MethodsThis cross-sectional study included ten apparently healthy people who had been submitted to a protocol on a cycle ergometer for 35 minutes. Autonomic modulation was evaluated by spectral analysis of HR variability (HRV).ResultsA relevant increase in HR response was observed at 15 minutes postexercise with intensities of 60% and 40% of the maximum HR (10±2 bpm versus 5±1 bpm, respectively; P=0.005), and a significant reduction in HRV was also noted with 40% and 60% intensities during the rest period, and significant reduction in HRV (RR variance) was also observed in 40% and 60% intensities when compared to the baseline, as well as between the post-exercise intensities (1032±32 ms versus 905±5 ms) (P<0.001). In the HRV spectral analysis, a significant increase in the low frequency component HRV and autonomic balance at 40% of the maximum HR (68±2 normalized units [nu] versus 55±1 nu and 2.0±0.1 versus 1.2±0.1; P<0.001) and at 60% of the maximum HR (77±1 nu versus 55±1 nu and 3.2±0.1 versus 1.2±0.1 [P<0.001]) in relation to baseline was observed. A significant reduction of high frequency component at 40% and 60% intensities, however, was observed when compared to baseline (31±2 nu and 23±1 nu versus 45±1 nu, respectively; P<0.001). Moreover, significant differences were observed for the low frequency and high frequency components, as well as for the sympathovagal balance between participants who reached 40% and 60% of the maximum HR.ConclusionThere was an increase in the HR, sympathetic modulation, and sympathovagal balance, as well as a reduction in vagal modulation in the elderly at both intensities of the PEX.

Spectral Analyses of Heart Rate Variability by Acceleration Plethysmography for Diagnostic Support of Migraine: Clinical Research

It is suspected that the pathophysiology of migraine has a relation to the autonomic dysfunction. We studied to assess the autonomic function in migraine using the spectral analysis of heart rate variability (HRV) by accelerated plethysmography (APG). Five-hundred-twenty-four patients received the health check-ups in an affiliated hospital since September, 2011 to April, 2013. Eighty-three patients with headache and 38 controls were enrolled in this study. The patients were subdivided into 19 with migraine (19 female), 26 with tension-type headache (TTH) (7 male, 19 female) and 31 of other headaches using a questionnaire based on the International Classification of Headache Disorders 2nd Edition. Patients with migraine or tension-type headache underwent examinations using APG with an orthostatic load. Twenty-four controls without headache received same examinations. As a result, the standing/sitting ratio of spectral power of high-frequency (HF) in the migraine group was higher than those of TTH (p=0.0277) and normal controls (p=0.0104). The cut-off value of 1.058 could separate migraine from TTH with sensitivity of 0.632 and specificity of 0.846. The results suggested that the parasympathetic activity accentuated by orthostatic load in patients with migraine, on the contrarily the parasympathetic activities diminished by orthostatic load in patients with TTH or normal controls. This study showed that spectral analysis of HRV by APG is a supportive tool to distinguish migraine from TTH.

Comparison of Electrocardiographic Findings and Holter Recordings in Patients with Behcet�s Disease and Healthy Volunteers

Comparison of Electrocardiographic Findings and Holter Recordings in Patients with Behcet’s Disease and Healthy Volunteers Objective: Behcet’s disease (BD) is known as a chronic relapsing, inflammatory process manifesting with multi systemic involvement. The aim of this study was to compare resting electrocardiography (ECG), exercise ambulatory ECG and Holter recording findings and autonomic nervous system (ANS) function in patients with BD versus healthy volunteers. Methods: The present study involved 90 subjects including 54 patients with BD (42 female, 12 male, mean age 29.8 ± 8.1 years) and 36 healthy volunteers (24 female, 12 male, mean age 28.1 ± 4.7) as a control group. All patients and controls had 12 lead ECG recorded at rest and exercise stress test. Digital ECG files were retrieved and analyzed with use of a software system. The corrected QT interval (QTc) was calculated by Bazzet’s formula. To test autonomic nervous system function, heart rate variability (HRV) studies were performed Results: Basal clinical, hematologic and biochemical characteristics were similar between groups. PR interval was longer in patients than in controls (161 ± 10, 145 ± 11, respectively, p=0.0005) however atrioventricular block was not detected in any group. Basal heart rate, QRS duration and QTc were similar between groups. All exercise ECG parameters were similar between groups. SDNN was less in patients than in controls; however SDANN was similar in both groups. There was a decrease in RMSSD and PNN50 and this finding was compatible with decreased HRV. Conclusions: Our data suggest that patients with BD may have asymptomatic ANS dysfunction, which is in the form of increased sympathetic and decreased parasympathetic modulation, and power spectral analysis of HRV is beneficial in assessing the ANS function. Also, we concluded that rest and exercise ECG cannot be used to evaluate cardiac involvement in BD.

Heart rate variability to assess ventilatory threshold in ski-mountaineering

The capacity to predict the heart rate (HR) and speed at the first (VT1) and second (VT2) ventilatory thresholds was evaluated during an incremental ski-mountaineering test using heart rate variability (HRV). Nine skiers performed a field test to exhaustion on an alpine skiing track. VT1 and VT2 were individually determined by visual analysis from gas exchanges (VT1V and VT2V) and time-varying spectral HRV analysis (VT1fH, VT2fH and VT2H). VT1 could not be determined with the HRV methods used. On the contrary, the VT2 was determined in all skiers. No significant difference between HR and speed at VT2H and VT2V was observed (174.3 ± 5.6 vs. 174.3 ± 5.3 bpm, and 6.3 ± 0.9 and 6.3 ± 0.9 km h–1, respectively). Strong correlations were obtained for HR (r = 0.91) and speed (r = 0.92) at VT2H and VT2V with small limits of agreement (±3.6 bpm for HR). Our results indicated that HRV enables determination of HR and speed at VT2 during a specific ski-mountaineering incremental test. These findings provide practical applications for skiers in order to evaluate and control specific training loads, at least when referring to VT2.