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• The objective of our study was to compare the response of autonomic system parameters (blood pressure, ECG, heart rate variability) in healthy subjects while listening to Indian classical music of different fractal qualities. • To quantify the complexity of a musical phrase we have used the Higuchi fractal dimension. • Indian classical music has the unique quality of slow transition betwen notes, with consequent changes in dimensions of the string being played, which we have quantified in the study. • 25 healthy volunteers were recruited, all between 18 and 35 years of age. The subjects were randomised into three groups: sinewave, low fractal music and high fractal music. • Electrocardiogram (ECG) and Non invasive BP (NIBP) leads were placed and continuous measurements started 10 min prior to intervention. At 0 min, the standardised musical intervention/ control was played. • During intervention, the fractal dimension of the BP waveform showed a significant difference between subjects of high fractal group and low fractal group. The Hurst exponent and sample entropy of the waveform was also measured. • In addition, the increment in heart rate variability during intervention showed an increasing trend from high to low fractal to sinewave. • Whether the changes are due to direct contact with source of music or through a cerebral mechanism can be ascertained by further studies. Music is an external stimulus that affects physiological systems; both the quality of music and the resultant physiological changes can be quantified, which presents an unique opportunity. To quantify the complexity of a musical phrase we have used the Higuchi fractal dimension. We then compared the response of autonomic system (blood pressure, ECG, heart rate variability) in healthy subjects while listening to Indian classical music of different fractal qualities. Indian classical music has the unique quality of slow transition between notes, with consequent changes in dimensions of the string being played, which we have quantified. 25 healthy volunteers were recruited, all 18–35 years of age; the subjects were randomised into three groups: sinewave, low fractal and high fractal, depending on the type of musical intervention. The subjects were placed in a quiet room and asked to perform deep breathing exercises for relaxation. Electrocardiogram (ECG) and Non invasive BP (NIBP) leads were placed and continuous measurements started 10 min prior to intervention. At 0 min, the standardised musical intervention/ control was played. During intervention, the fractal dimension of the BP waveform showed a significant difference between subjects of high fractal group and low fractal group. In addition, the increment in heart rate variability (measured by standard parameters) during intervention showed an increasing trend from high to low fractal to sinewave. Whether the changes are due to direct contact with source of music or through a cerebral mechanism can be ascertained by further studies. [ABSTRACT FROM AUTHOR]

To detect and quantify the directional interaction changes between cardio-respiratory system during postural change. Traditional frequency domain analysis based on power spectrum and coherence are insufficient to quantify nonlinear structures and complexity of physiological subsystems. Recently, Granger causality is found as preferable method for evaluation of causality i.e., directional interaction. Frequency domain Granger causality based on directed coherence has been used in this study to identify directional interaction between cardiac and respiratory signal during postural change from supine to standing for healthy subjects. ECG and respiration signal are recorded for this study. The beat-to-beat variability series from ECG provides heart rate (RR) and the respiration amplitude corresponds to RESP time series. It was observed that respiration is responsible for the changes in ECG signal during supine position as compared to standing. The outflow of information from RESP to RR increases during supine results in stronger interaction but reduces during standing result in reduction of interaction. Similarly, the effect of RR on RESP is found significant only during standing. The proposed directed coherence approach detects the cardio-respiratory regulation during postural change and provide information about coupling changes during this transition. • Importance of deriving Directed Coherence spectrum on cardiorespiratory system. • Directed coherence spectrum obtains directional interaction among system. • Effect of RESP to RR increases during supine but decreases during standing. • Effect of RR to RESP is found significant only during standing. [ABSTRACT FROM AUTHOR]

To investigate the effect of resistance training (RT) on outcomes of cardiac autonomic control, biomarkers of subclinical inflammation, endothelial dysfunction, and angiotensin II in T2DM patients with CAN. Fifty six T2DM patients with CAN were recruited in the present study.After baseline assessment of all outcome variables, patients were randomly allocated into two groups – RT (n = 28) and Control (n = 28). The experimental group underwent 12 weeks of RT and the control group received usual care. RT was performed at an intensity of 65%–75% of 1 RM, 3 times/week for 12 weeks. RT program included 10 exercises of major muscle groups in the body. Cardiac autonomic control parameters, subclinical inflammation and endothelial dysfunction biomarkers, and serum angiotensin II concentration were assessed at baseline and after 12 weeks. Parameters of cardiac autonomic control showed significant improvement after RT (p < 0.05). Interleukin-6, interleukin-18 were significantly reduced while endothelial nitric oxide synthase was significantly increased post-RT (p < 0.05). Findings of the present study suggest that RT has the potential to enhance deteriorating cardiac autonomic function in T2DM patients with CAN. RT also seems to have an anti-inflammatory role and it may also play some role in vascular remodeling in these patients. CTRI/2018/04/013321 , Registered prospectively on 13th April 2018, Clinical Trial Registry, India. • Progressive resistance training (PRT) improves deteriorating cardiac autonomic function in type 2 diabetes mellitus. • PRT down-regulates subclinical inflammation in type 2 diabetes mellitus patients with cardiac autonomic neuropathy (CAN). • PRT improves vascular endothelial function in type 2 diabetes mellitus patients with CAN. • Present study reinforces the utilization of PRT as an adjunct intervention for type 2 diabetes mellitus patients with CAN. [ABSTRACT FROM AUTHOR]

This quantitative study delineates the influence of respiratory rate on cardiovascular signal in healthy subjects using granger causality approach. Electrocardiogram ( RR ), arterial blood pressure ( SBP ) and respiration ( RESP ) were simultaneously recorded for 5 min from 20 subjects during normal (13–20 cycles/min) and deep breathing (5 cycles/min) with equal inspiration and expiration time. During deep breathing mean RR remains same but the variance increases. Also deep breathing lowers blood pressure, increases baroreflex sensitivity and improves oxygen saturation. The traditional frequency domain methods based power spectrum analysis and coherence analysis lacks to measure coupling changes among physiological subsystems. Therefore, frequency domain Granger causality method based on directed coherence is proposed to detect the changes in coupling strength among cardiovascular signals under different respiration rates. Directed coherence spectrum can separate RESP , SBP and RR components from each recorded signals. The RESP component of both RR ( RR RESP ) and SBP ( SBP RESP ) increases (coherence > 0.5) significantly during deep breathing indicate that respiration affects both cardiac and vascular system but at normal breathing only cardiac system ( RR RESP ) get affected by respiration. Also a significant increase in coherence is observed on baroreflex direction ( RR SBP ) indicating that deep breathing controls blood pressure. Hence, the observed directed coherence spectrum helps to detect coupling changes among cardiac, vascular and respiratory signal during autonomic regulation. [ABSTRACT FROM AUTHOR]

• The conditional entropy technique enabled simultaneous analysis of heart-brain rhythms. • Directional coupling information C (heart→brain) and C (brain→heart) differentiated internally and externally operative attention. • Attention states were examined using simultaneous recording of EEG and ECG signals. • A modified Posner's spatial orienting task used to assess A I and A E attention. • Internal and external attention states investigated using identical stimulus design. Heart and brain interactions mediate human cognition. This investigation identifies heart-brain interactions during internally operative attention (A I) and externally operative attention (A E). A I attention involves short term memory, whereas A E attention deals with automatic and transient response to objects in the external world. A modified Posner's spatial orienting task used to differentiate A I and A E attention. Heart and brain rhythms recorded in fourteen healthy participants. Functional coupling from heart-to-brain (C h e a r t → b r a i n) and brain-to-heart (C b r a i n → h e a r t) time series derived using an information domain approach based on conditional entropy. The experimental results showed that low-frequency power of heart rate variability (HRV-LF) and sympathovagal balance (LF/HF ratio) during A E significantly increased compared with that for A I. Furthermore, the information flow from heart-to-brain increased and decreased form brain-to-heart during A E as compared to A I. Also, opposite trend in relationship noted between coupling index (C i → j) and HRV-LF during A I and A E attention. The conditional entropy technique enabled simultaneous analysis of heart-brain rhythms to identify heart-brain interactions during A I and A E attention. [ABSTRACT FROM AUTHOR]

Lower body negative pressure (LBNP) has been employed in multiple countermeasure protocols against post spaceflight orthostatic hypotension. However, protocols utilizing oscillatory LBNP (oLBNP) have not been explored in this regard. oLBNP has shown promise in few studies to have good tolerance in conditions of hypovolemic stress and since the negative suction is only phasic, the extravascular fluid shifts associated with negative suction are also hypothesized to be less. Our study addressed the paucity of information on oLBNP by investigating the cardiovascular and neurohormonal effects of oLBNP of −15 and −45 mm Hg in 40 healthy adult males (mean age = 29.6 ± 4.7 years, BMI = 25.1 ± 3.6 kg/m2). After supine rest of 10 min (baseline), oLBNP was applied at −15 mm Hg and −45 mm Hg for 10 min each with a gap of 10 min. Blood sample for neurohormonal analysis was collected at the end of baseline and after each oLBNP exposure. Blood pressure, heart rate, respiratory rate and end tidal CO 2 (EtCO 2) were recorded for the entire duration. Serum angiotensin II (ATII), antidiuretic hormone (ADH) and atrial natriuretic peptide (ANP) were analyzed using ELISA. On comparison with the baseline [SBP: 114 ± 2.38, MBP: 75.8 ± 2.16 mm Hg] there was a significant fall in SBP on application of −15 mm Hg as well as −45 mm Hg oLBNP[-15 oLBNP: 107.4 ± 2.34 mm Hg; −45 oLBNP: 105.3 ± 2.28 mm Hg], while there was no significant difference observed in the DBP. There was a significant increase in the heart rate at both −15 [77.29(72.75–85.65) BPM] and −45 mm Hg [81.29 (73.93–86.09) BPM] oLBNP as compared to the baseline [70.41(64.32–79.80) BPM]. No significant difference in the serum ATII, ADH and ANP after 10 min of application of −15 or −45 mm Hg oLBNP as compared to baseline was observed. In conclusion, oLBNP induced legward pooling of blood causes a fall in the blood pressure which initiates the neural reflex mechanisms, most important being the baroreflex and the cardiopulmonary reflex. However, since there was no significant difference in the serum ATII, ADH and ANP from baseline, this suggests that 10 min oLBNP up to −45 mm Hg results in recruitment of cardiovascular neural reflex response but it does not evoke neurohormonal responses which mediate long term volume changes. • -45 mm Hg Oscillatory LBNP (oLBNP) evoked blood pressure drop & elevation in heart rate. • However, the serum ATII, ADH and ANP remain unchanged after the same protocol. • oLBNP causes recruitment of cardiovascular reflexes but not hormonal response. [ABSTRACT FROM AUTHOR]

Low-flow-mediated constriction (LFMC) has been used to assess resting endothelial function in peripheral conduit arteries. The literature describes discrepancies in the behaviour of radial versus brachial artery in response to low-flow state, the reasons for which were not addressed in a systematic and scientific way. Moreover, the influence of handedness on observed LFMC responses has not been investigated. The present study aimed at systematic measurement and comparison of the LFMC responses in radial and brachial arteries of both dominant and non-dominant arms of healthy human volunteers. We also investigated the physiological factors associated with differential LFMC response of radial versus brachial artery in the same group of subjects. Longitudinal B mode ultrasonographic cine loops of radial and brachial arteries were acquired at baseline and after producing distal circulatory arrest. Cine loops were screen grabbed and analyzed later using automated edge detection algorithms to measure end-diastolic diameters. Distal circulatory arrest was produced over the proximal forearm (for the brachial artery) and over the wrist (for the radial artery) at 250 mm Hg for 5 min after baseline measurements. Results suggested that arterial location (p = 0.0001) and baseline diameter (p < 0.0021) emerged as independent predictors of LFMC response. Differences in the LFMC responses are handedness independent and could be attributed to the arterial location along with the differences in their baseline diameters. [ABSTRACT FROM AUTHOR]

Background: Autonomic dysfunction is common in children with Rett syndrome. They usually manifest with agitation, persistent screaming, constipation, gastroesophageal reflux, aerophagia, hyperventilation, and breath-holding episodes. Cardiovascular autonomic dysfunction may result in fatal a arrhythmia. Many of these events are mistaken for seizures and treated with antiepileptics.Methods: The present study was conducted in a tertiary care teaching hospital in north India for more than a six month period. MeCP2 mutation positive, 24 cases with Rett syndrome and 24 age-matched healthy girls were evaluated for cardiovascular autonomic dysfunction (heart rate variability, head-up tilt test, and cold pressor test).Results: The mean age was 9.06 years (±3.4) and 9.75 years (±3.13) for patients and control subjects, respectively. The heart rate variability contributed independently by parasympathetic and sympathetic nervous system was significantly reduced in cases compared with control subjects (P = 0.033 and P = 0.001, respectively). There was significant sympathovagal imbalance with sympathetic overactivity in cases compared with control subjects (P = 0.001). The mean longest QTc interval was significantly prolonged in cases compared with control subjects (P = 0.001). Cold pressor test and head-up tilt test could be done in 16 Rett syndrome patients (because of poor cooperation) and in all 24 control subjects. The change in blood pressure during cold pressor test and head-up tilt test was not significantly different in cases and control subjects.Conclusions: Children with Rett syndrome exhibited significant cardiovascular autonomic dysfunction in the form of sympathetic overactivity, parasympathetic underactivity, and sympathovagal imbalance. These findings have potentially important therapeutic- and outcome-related implications. [ABSTRACT FROM AUTHOR]

Abstract: Cushing''s syndrome is associated with increased cardiovascular morbidity and mortality. It''s also associated with other cardiac risk factors like hypertension, diabetes mellitus and obesity. Cardiovascular autonomic function impairment could predict cardiovascular morbidity and mortality. Twenty five patients with Cushing''s syndrome without diabetes and twenty five age matched healthy controls underwent a battery of cardiovascular autonomic function tests including deep breath test, Valsalva test, hand grip test, cold pressor test and response to standing from lying position. The rise in diastolic blood pressure on hand grip test and diastolic BP response to cold pressor test in Cushing''s patients were significantly less compared to healthy controls (9.83±3.90 vs 20.64±9.55, p <0.001 and 10.09±4.07 vs 15.33±6.26, p <0.01 respectively). The E:I ratio on deep breathing test was also less in the patients in comparison to controls (1.36±0.21 vs 1.53±0.19, p <0.01). Seven patients underwent the same battery of tests 6months after a curative surgery showing a trend towards normalization with significant improvement in expiratory to inspiratory ratio and sinus arrhythmia delta heart rate. To conclude, this study showed that chronic endogenous hypercortisolism in Cushing''s is associated with an impaired sympathetic cardiovascular autonomic functioning. After a curative surgery, some of the parameters tend to improve. [Copyright &y& Elsevier]

Abstract: Cardiac autonomic functions were assessed in 145 consecutive recently detected type 2 diabetics. Ninety-nine healthy persons served as controls. Criteria for normalcy were, heart rate variation during deep breathing ≥15beats/min, deep breathing expiratory to inspiratory R–R ratio ≥1.21, Valsalva ratio ≥1.21, sustained handgrip test ≥16mm of mercury, cold pressor test ≥10, BP response to standing ≤10mm of mercury and 30:15 R–R ratio on standing ≥1.04. An abnormal test was defined as the above parameters being <10beats/min, <1.21, <1.21, ≤10mm of mercury, <10, ≥30mm of mercury and ≤1.0, respectively. A borderline test was defined as, heart rate variation during deep breathing 11–14, sustained handgrip test 11–15mm of mercury, BP response to standing 11–29mm of mercury and 30:15 R–R ratio on standing 1.01–1.03. Parasympathetic dysfunction was found in 44.2% and sympathetic dysfunction in 51.9% diabetics. Among healthy controls, these figures were 11.9% and 22.1%, respectively. Cardiac autonomic function was normal in 7.8% patients and 32.5% healthy controls. [Copyright &y& Elsevier]

Background: Heart rate variability (HRV) is a marker of cardiac autonomic tone. Depressed HRV has been reported in patients with AIDS. We conducted this study to find out if HRV is depressed in human immunodeficiency virus (HIV)-positive individuals without AIDS. Methods: We studied prospectively HRV by spectral analysis of short-term electrocardiography (ECG) monitoring in 21 HIV-positives (33±11 years) and in 18 healthy volunteers (31±9 years). None of the HIV-positives had any clinical evidence of autonomic or cardiac dysfunction. Echocardiography was also performed in HIV-seropositives to rule out left ventricular (LV) systolic dysfunction. All these individuals did not have any evidence of AIDS. Results: Mean CD4+ lymphocyte count was 426±166/mm3. The ejection fraction (EF%) of HIV patients was 62.4±6.4.The total power of HRV was reduced significantly in HIV-positive individuals (p<0.00001). All the components of HRV were reduced. Conclusions: HRV is reduced in HIV-seropositive individuals in early stages of infection as well without any clinical evidence of autonomic dysfunction. This may serve as an early marker of future global sympatho-vagal imbalance. [Copyright &y& Elsevier]

Introduction/Background Fibromyalgia (FM) is a multi-symptomatic disorder with a varying degree of widespread pain in the body. With emerging evidences pathophysiological concept shifted from peripheral damage or inflammation to central neural mechanism. Fibromyalgia is characterised by dysfunction in central pain processing, “central sensitivity”. In this cross-sectional study central sensitization was recorded in patients with fibromyalgia by observing cortical oxygenation in prefrontal cortex using Functional Near Infrared Spectroscopy (fNIRS). Material and method fNIRS 300B (BIOPAC), a wearable continuous fNIRS system with 4 optode and 16 detectors was used to assess changes in oxy-haemoglobin concentration (μM) from Brodmann areas 9, 10, 45 and 46. Number of activation (max and 60% max signals) was compared in time series of Oxygenated Haemoglobin level with Rt foot immersed in ice cold water. For comparison of categorical variable, sex Chi 2 test was used. For non-parametric data, i.e. age and fNIRS data Mann–Whitney U test was used. Both of the test was done in SPSS Statistics 23 by IBM, Chicago, IL with a confidence interval of 95% and a significance level lower than 5%. Results Fifty FM patients diagnosed according to ACR 2010 fibromyalgia criteria and equal number of age and sex matched controls were enrolled in the study. There was increased oxygenation in FM compared to control in prefrontal cortex. Conclusion This increased oxygenation in prefrontal cortex in FM group objectively demonstrates alteration in central activity in FM group. Changes in central activity along with pain hypersensitivity in FM points towards central sensitisation. Lack of 3D digitiser restrict us to comment on localisation of activation. fNIRS can be used as tool to evaluate central sensitization. [ABSTRACT FROM AUTHOR]