Cardiovascular dysfunctions and sympathovagal imbalance in hypertension and prehypertension: physiological perspectives

Clinical Implication of Maumgyeol Basic Biotypes-Electroencephalography- and Photoplethysmogram-Based Bwave State Inventory

OBJECTIVE

The development of individual subtypes based on biomarkers offers a cost-effective and timely avenue to comprehending individual differences pertaining to mental health, independent from individuals' subjective insights. Incorporating 2-channel electroencephalography (EEG) and photoplethysmogram (PPG), we sought to establish a subtype classification system with clinical relevance.

METHODS

One hundred healthy participants and 99 patients with psychiatric disorders were recruited. Classification thresholds were determined using the EEG and PPG data from 2,278 individuals without mental disorders, serving to classify subtypes in our sample of 199 participants. Multivariate analysis of variance was applied to examine psychological distinctions among these subtypes. K-means clustering was employed to verify the classification system.

RESULTS

The distribution of subtypes differed between healthy participants and those with psychiatric disorders. Cognitive abilities were contingent upon brain subtypes, while mind subtypes exhibited significant differences in symptom severity, overall health, and cognitive stress. K-means clustering revealed that the results of our theory-based classification and data-driven classification are comparable. The synergistic assessment of both brain and mind subtypes was also explored.

CONCLUSION

Our subtype classification system offers a concise means to access individuals' mental health. The utilization of EEG and PPG signals for subtype classification offers potential for the future of digital mental healthcare.

Inflammation and decreased cardiovagal modulation are linked to stress and depression at 36th week of pregnancy in gestational diabetes mellitus

Stress and depression have been reported in gestational diabetes mellitus (GDM). Though inflammation and oxidative stress are associated with depression, there are no reports of link of cardiometabolic risks (CMR) to stress and depression in GDM. Normal pregnant women (control group, n = 164) and women with GDM (study group, n = 176) at 36th week of gestation were recruited for the study. Blood pressure (BP), body composition, heart rate variability (HRV), glycated hemoglobin (HbA1C), markers of insulin resistance, oxidative stress, inflammation and endothelial dysfunction, were assessed. Perceived stress score (PSS), quality of life (QoL) scale, Indian diabetic risk score (IDRS) and Edinburg postnatal depression score (EPDS) were assessed. Association of potential contributors to PSS and EDPS were assessed by correlation and regression analyses. There was significant increase in PSS, EPDS, IDRS scores, HbA1C, malondialdehyde (MDA) (oxidative stress marker) and high-sensitive C-reactive protein and interleukin-6 (inflammatory markers), and significant decrease in total power (TP) of HRV (marker of cardiovagal modulation), QoL and nitric oxide (endothelial dysfunction marker) in study group compared to control group. Though many cardiometabolic risk parameters were correlated with PSS and EPDS, the significant independent association was observed for TP, HbA1C, MDA and interleukin-6. However, interleukin-6 had maximum contribution to PSS (β = 0.550, p < 0.001) and EPDS (β = 0.393, p < 0.001) as demonstrated by multiple regression analysis. Inflammation, oxidative stress, glycation status and decreased cardiovagal modulation are associated with stress and depression at 36th week of gestation in GDM.

Comparison of cardiac autonomic function across complete glycaemic spectrum

OBJECTIVES

Autonomic imbalance is attributed as key mechanism altering metabolic regulation in diabetes mellitus. In view of controversial reports on autonomic function in FDRD and prediabetes, we aimed to assess and compare the autonomic function across the complete glycaemic spectrum in Indian population.

METHODS

Short term heart rate variability and cardiac autonomic reactivity tests - blood pressure and heart rate response to orthostatic tolerance and deep breathing exercise, and diastolic response to isometric handgrip exercise were recorded in normoglycemic apparently healthy individual, normoglycemic first degree relatives of diabetes, prediabetes and diabetes individuals.

RESULTS

Resting heart rate is significantly higher in FDRD, prediabetes and diabetes as compared to controls (control < FDRD = prediabetes = diabetes). Total power, LF power (control < FDRD < prediabetes = diabetes) and HF power (control < FDRD < prediabetes < diabetes) decreased along the glycaemic spectrum. Time-domain variables of HRV (SDNN, RMSSD, NN50, pNN50) were reduced as we move along the glycaemic spectrum (control < FDRD < prediabetes = diabetes). Cardiac autonomic function reactivity parameters such as 30:15 ratio and E:I ratio are decreased in prediabetes and diabetes group as compared to control and FDRD group (control = FDRD < prediabetes = diabetes). Diastolic response to isometric hand grip increases along the glycaemic spectrum starting from FDRD (control < FDRD < prediabetes = diabetes).

CONCLUSIONS

Autonomic dysfunction is observed even in first degree relatives of diabetes. Autonomic dysfunction increases as we move along the glycaemic spectrum (control < FDRD < prediabetes < diabetes).

Electrochemical skin conductance and heart rate variability in patients with non-dialysis chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is very common now and associates with high overall and cardiovascular mortality. Numerous studies have reported that Heart rate variability (HRV) could also be used to detect cardiovascular autonomic dysfunction (CAD). We investigated the association of electrochemical skin conductance (ESC) of EZSCAN results with HRV in non-dialysis CKD patients.

METHODS

In a cross-sectional study, we enrolled 248 prevalent non-dialysis CKD patients. Patients underwent a 24-h Holter (CB-2302-A, Bio Instrument, China). A time domain analysis of HRV was performed, and the following parameters were obtained: SDNN, SDANN, rMSSD, pNN50. EZSCAN device (Impeto Medical, Paris, France) measures ESC values of each participants. Mean global skin conductance computed as 0.5 * (reflecting (right + left hand)/2 + (right and left foot)/2). Log transforms data into a normal distribution for statistical analysis.

RESULTS

There were 142 males and 106 females included in the present study. Patients' age was 56.6±17.08 years. Logarithm(Log) (global ESC) was independently predicted by age (P<0.01), hypertension history, estimated Glomerular filtration rate (eGFR) and log SDNN (P<0.05). While log SDANN, rMSSD and pNN50 were not independent predictors for log (global ESC).

CONCLUSION

Increased global ESC significantly associated with elevated HRV, specifically SDNN in non-dialysis CKD patients. This suggested that global ESC may appear to be an important predictor of CAD, and even could be used as a cardiovascular risk factor in non-dialysis CKD patients.

Immediate autonomic changes during right nostril breathing and left nostril breathing in regular yoga practitioners

BACKGROUND

The ancient Indian science of Yoga makes use of voluntary regulation of breathing to make respiration rhythmic and calm the mind. This practice is called pranayama. Nadisuddhi pranayama means "purification of subtle energy paths," inhalation and exhalation are through alternative nostrils for successive respiratory cycles. Surya Anuloma-Viloma pranayama means "heat generating breathing particle" when the respiratory cycle of inhalation and exhalation is completed through the right nostril exclusively. When completed through the left nostril alone, the practice is called "Chandra Anuloma-Viloma pranayama," which means a heat-dissipating or cooling liberating practice. We compared the effect of right nostril breathing (RNA) and left nostril breathing (LNB) pranayama on heart rate variability.

MATERIALS AND METHODS

The study was conducted at the Department of Physiology at an institute of national importance, after obtaining necessary ethical approvals from the Institutional Ethics Committee. Twenty healthy kriya yogi volunteers (mean age: 44 years), who are regular practitioners for the last 10-20 years, were inducted into the study. RNB pranayama starts with closing the right nostril with the thumb of the left hand followed by exhalation through the right nostril and inhaling slowly through the same nostril. This forms one round of RNB pranayama. In contrast, inhalation through the left nostril and exhalation through the right nostril exclusively is called chandrabhedana pranayama (chandrabhedana means moon-piercing breath in Sanskrit) with a similar variation called Chandra Anuloma-Viloma pranayama in which inhalation, as well as exhalation, is performed through the left nostril exclusively. The recording of electrocardiogram (ECG) for heart rate variability (HRV) analysis was taken by heart rate variability (Dinamika HRV-Advanced Heart Rate Variability Test System, Moscow, Russia). The resting and during readings of heart rate variability parameters were compared and post hoc analysis was done using Bonferroni and Holm multiple comparisons for repeated measures.

RESULTS

Time domain parameters: Standard deviation of normal to normal RR intervals (SDNN) and root mean square of successive NN interval differences (RMSSD) were increased at a high level of statistical significance during both pranayama maneuvres. Frequency domain parameters: LF, LF/HF ratio increased significantly. Parasympathetic activity is represented by LF when the respiration rate is lower than 7 breaths per min or during taking a deep breath. Thus, when the subject is in a state of relaxation with slow and even breathing in both RNB-right nostril and Chandra-LNB, the LF values can be very high, indicating an increase in parasympathetic activity rather than an increase in sympathetic regulation.

CONCLUSION

Our study is an acute study, where changes in HRV were seen after 5 min of RNB and LNB. However, statistically, there is not much difference in the immediate effects of the two pranayamas on heart rate variability in regular yoga practitioners.

Feasibility of using ecological momentary assessment and continuous heart rate monitoring to measure stress reactivity in natural settings

The way people respond to stressful situations (i.e., stress reactivity) varies widely. Researchers typically measure stress reactivity in controlled studies, but this is limited because laboratory stressors cannot capture the variety, severity, or duration of stressors that individuals face in their daily lives. The present study examined the feasibility of using ecological momentary assessment (EMA) and a wireless electrocardiography (ECG) patch to develop an understanding of stress reactivity in natural settings. Thirty-five adult women completed EMA surveys about stressors they were exposed to while wearing a wireless ECG monitor for 7 consecutive days. Daily stressors were measured using seven questions adapted from the Daily Inventory of Stressful Events and a stressor interval was defined as the presence of at least one stressor during the EMA survey prompt. Participants wore the Cardea SOLO wireless ECG monitor (Cardiac Insight Inc., Bellevue, WA) to continuously track their heart rate. Participant-specific differences in 5-minute heart rate variability (HRV) between intervals when participants did and did not report stressors were calculated and displayed in a heat map. Survey response rate was satisfactory (72.0%, n = 588) and nearly all participants (33 out of 35) reported both stressor and non-stressor intervals. Each participant reported at least one stressor on approximately 35% of completed surveys while wearing the ECG patch. Mean wear time (6.6 days) and the duration of analyzable data with an ECG monitor were close to the 7-day study period. While many participants had lower HRV during stressor versus non-stressor intervals, the magnitude and direction of these differences varied widely. In summary, we found that a 7-day sampling scheme combining ecological momentary assessment (EMA) with HRV measured using continuous ECG monitoring was feasible and effective in capturing a variety of daily stressors and measuring autonomic stress reactivity.

Cardiac Autonomic Modulation is a Key Factor for High Blood Pressure in Adolescentes

Fundamento

O interesse pela hipertensão em crianças e adolescentes aumentou desde a atualização do sistema de classificação da pressão arterial para comparar com o sistema de classificação dos adultos, alterando a terminologia de “normal alta” para “pré-hipertensão”.

Objetivo

O objetivo deste estudo foi analisar a associação da modulação autonômica cardíaca com os níveis pressóricos dos adolescentes.

Métodos

203 adolescentes foram agrupados de acordo com a pressão arterial sistólica (PAS) e a pressão arterial diastólica (PAD). Um grupo foi caracterizado como pré-hipertensão, e o outro como normotenso. Foram coletadas características antropométricas, cardiovasculares e de qualidade do sono. Inicialmente, os dados foram submetidos ao teste de normalidade Kolmogorov-Smirnov . As variáveis quantitativas contínuas foram analisadas por meio do teste T de Student não pareado. Para análise das variáveis categóricas, foi utilizado o teste qui-quadrado. Um modelo de regressão logística foi realizado. O nível de significância estabelecido foi p<0,05. Os dados foram expressos como média ± desvio padrão e intervalo de confiança. O software R foi utilizado para análise dos dados. O tamanho do efeito foi calculado com a fórmula de Cohen.

Resultados

O grupo pré-hipertensão apresentou aumento da entropia de Shannon e diminuição da variância total. Além disso, no modelo de regressão logística, os adolescentes deste grupo tiveram 1,03 mais chances de ter a entropia de Shannon afetada quando a PAS foi ajustada ao gênero, maturação sexual, tempo escolar, idade, circunferência da cintura e qualidade do sono.

Conclusão

Nossos dados mostram que a modulação autonômica pode desempenhar um papel importante no desenvolvimento da pressão arterial elevada em adolescentes ao controlar fatores como tempo escolar e qualidade do sono.

Effects of 12 Weeks Practice of Yoga on Heart Rate Variability in Males with Type 2 Diabetes Receiving Oral Antidiabetic Drugs: A Randomized Control Trial

Objective: To investigate the effects of 12 weeks practice of a structured yoga module on heart rate variability (HRV) and cardiometabolic risks in patients with type 2 diabetes (T2D) receiving similar kind of oral antidiabetic drugs (OAD) with yoga therapy and without yoga therapy, matched for all the known confounders. Design: Parallel design interventional (randomized control trial) study. Subjects: Eighty treatment-naive males with T2D were randomized into control group (n = 40) and study group (n = 40). Intervention: Study group participants received a structured yoga therapy that included asana and pranayama practice for 12 weeks in addition to OAD, whereas control group participants received OAD alone. Outcome measures: Before and after intervention, BP parameters, rate pressure product (RPP) as the marker of myocardial stress, total power (TP) of HRV, low-frequency to high-frequency (LF-HF) ratio of HRV, homeostatic model of insulin resistance (HOMA-IR), lipid profile and lipid risk factors, malondialdehyde (MDA), and high-sensitive C-reactive protein (hsCRP) were measured. TP of HRV was defined as the primary outcome. Association of TP (the marker of HRV) and LF-HF ratio (the marker of sympathovagal balance) with cardiometabolic parameters was assessed by correlation and regression analyses. Results: After 12 weeks yoga therapy, there was significant reduction in cardiometabolic risks (TP of HRV, RPP, lipid risks factors, levels of MDA, and hsCRP) in study group subjects compared with control subjects that did not receive yoga therapy. All cardiometabolic risk factors were significantly correlated with TP in study group, having maximum significance with homeostatic model of insulin secretion (r = 0.502, p ≤ 0.001). Multiple regression analysis demonstrated the independent contribution of decrease in RPP, HOMA-IR, hsCRP, and MDA to increased TP and decreased LF-HF ratio in T2D patients after yoga therapy. Conclusion: From the results of this study, the authors conclude that 12 weeks practice of a structured yoga module improves TP of HRV, sympathovagal balance, and metabolic functions, and reduce cardiovascular (CV) risks in patients with diabetes who received routine antidiabetic medicines along with yoga therapy, compared with the patients with diabetes who received antidiabetic medicines alone. The reduction in cardiometabolic risks in these patients is linked to the improvement in TP of HRV. Future studies should also include a control group with rapid walking or a similar exercise program of equal time to the yoga intervention group to discern whether it is in fact yoga that is leading to these results and not simply increased CV activity. Clinical Trial Registry of India (No. CTRI/2021/06/034074).

Decreased baroreflex sensitivity is associated with cardiometabolic risks and prehypertension status in early-postmenopausal women

OBJECTIVE

We studied the link of decreased baroreflex sensitivity (BRS) to cardiometabolic risks and prehypertension status in postmenopausal women during their early menopausal phase.

METHODS

Premenopausal women (n = 55) and early-postmenopausal women (n = 50) of age group between 40 and 55 years were recruited for the study, and their anthropometric parameters, complete battery of autonomic function tests (AFT), BRS, hormone levels, and cardiometabolic risk parameters were measured and compared between two groups. Correlation analysis of BRS with various physiological and biochemical parameters in these two groups were performed. Multiple regression analysis of BRS with various other associated factors in postmenopausal subjects and bivariate logistic regression analysis for assessing prediction of prehypertension status by BRS in postmenopausal group were performed.

RESULTS

There was a significant difference in AFT and metabolic parameters between premenopausal and postmenopausal women. Sympathovagal imbalance (increased sympathetic and decreased parasympathetic) was prominent in early-postmenopausal women. Decreased BRS, the marker of cardiovascular (CV) risk was found to be significant (P < .001) and correlated with various cardiometabolic parameters in early-postmenopausal subjects. Multiple regression analysis demonstrated that decreased BRS is independently linked to parameters of decreased vagal activity, inflammation, and oxidative stress in early-postmenopausal group. Decreased BRS could predict prehypertension status in early-postmenopausal subjects as confirmed by bivariate logistic regression analysis.

CONCLUSION

Sympathovagal imbalance, decreased BRS and considerable metabolic derangements were observed in women in their early phase of menopause. Decreased BRS appears to be associated with the cardiometabolic risks in these women. Prehypertension status in early-postmenopausal subjects could be predicted by decreased BRS.

Attenuation of baroreflex sensitivity and heart rate variability is linked to reduced levels of nitric oxide in pregnant women having risks of developing gestational hypertension

Purpose: Decreased baroreflex sensitivity (BRS) and sympathovagal imbalance (SVI) have been reported as a cardiovascular (CV) risk in gestational hypertension (GH). Nitric oxide (NO) has been implicated in pathophysiology of GH. In the present study, we assessed the link of CV risks (decreased BRS and SVI) to the plasma levels of NO in women having risk of developing GH. Materials and Methods: A total of 96 pregnant women having risk factors for GH were recruited for the study. The blood pressure variability (BPV), heart rate variability (HRV), plasma NO, marker of insulin resistance (HOMA-IR), lipid risk factors, inflammatory markers (hsCRP, interleukin-6), and malondialdehyde (MDA), the marker of oxidative stress (OS) were measured at 16^th and 36^th week. Link of various parameters to NO was assessed by correlation and multiple regression analysis. Results: Of HRV indices, parasympathetic components were decreased and sympathetic components were increased, BRS was decreased, NO was decreased, HOMA-IR, lipid risk factors, hsCRP, interleukin-6, and MDA were increased significantly at 36^th week compared to 16^th week of pregnancy. Most of the markers of cardiometabolic risk were correlated with NO. However, only the markers of CV risk (SVI and reduced BRS) were independently associated with decreased level of NO, but not the metabolic markers except interleukin-6. The independent contribution of BRS (β = 0.334, P < .001) to NO was found to be most significant. Conclusion: It was concluded that decreased BRS, SVI, and increased interleukin-6 are associated with reduction in NO in GH, which may possibly be linked to the development of CV risks in GH.

A narrative review of prehypertension and the cardiovascular system: effects and potential pathogenic mechanisms

In 1939, Robinson and Brucer first proposed the concept of prehypertension (PHTN), which was defined as a systolic blood pressure of 120–139 mmHg and/or diastolic blood pressure of 80–89 mmHg. PHTN is a major global health risk that adversely affects human health, especially the cardiovascular system. People with PHTN have a higher risk of developing cardiovascular diseases, including stroke, coronary heart disease, myocardial infarction and total cardiovascular events. However, there are few systematic summaries of the relationship between PHTN and the cardiovascular system. Furthermore, because the definition of ‘normal BP’ and the advantages of more intensive BP control remain unclear, there is no consensus on optimal interventions. In an attempt to provide information for clinicians or professionals who are interested in reducing the risk associated with PHTN, we review the existing studies to provide references for them with the effects of PHTN on the cardiovascular system and the potential pathogenic mechanisms of PHTN, including inflammatory responses, insulin resistance, endothelial dysfunction, sympathovagal imbalance, activation of the renin-angiotensin system and others. PHTN is highly prevalent and has adverse effects on health. An effective public health strategy is important to prevent the progression of PHTN. We envisage that this information will increase the public attention of PHTN and help to provide more strategies to reduce the risk of cardiovascular events.

Increased osteoprotegerin level is associated with impaired cardiovagal modulation in type-2 diabetic patients treated with oral antidiabetic drugs

Background

An increased osteoprotegerin (OPG) level has been reported in both type-2 diabetes mellitus (T2DM) and cardiovascular diease (CVD) that are linked to sympathovagal imbalance (SVI). We explored the link of osteoprotegerin with cardiovagal modulation in T2DM.

Methods

We assessed fasting serum OPG, high-sensitive C-reactive protein (hsCRP), glucose, insulin and lipid profile in patients having T2DM receiving oral antidiabetic drugs (OAD) (n = 42) compared with age, gender and body composition-matched healthy participants without diabetes (n = 42). Rate pressure product (RPP), spectral indices of heart rate variability (HRV) and body composition were recorded in both the groups. Association of HOMA-IR and OPG with various parameters were assessed.

Results

Osteoprotegerin, HOMA-IR, hsCRP, coronary lipid risk factor were significantly increased, markers of cardiovagal modulation (TP, SDNN, RMSSD) were considerably decreased, ratio of low-frequency to high-frequency (LH-HF ratio), the indicator of SVI, and RPP, the marker of myocardial work stress were significantly higher in patients with diabetes, suggesting an overall elevated CVD risks in them. HOMA-IR was correlated with RMSSD, lipid risk factors and OPG. Rise in OPG was correlated with decreased cardiovagal modulation in patients with diabetes. There was significant contribution of OPG in decreasing TP, suggesting impaired cardiovagal modulation.

Conclusion

T2DM patients receiving OAD had higher cardiometabolic risks compared to age, gender and body composition-matched healthy individuals. Increased level of OPG is linked to decreased cardiovagal modulation in T2DM patients.

Investigation of heart rate variability and heart rate turbulence in chronic hypotensive hemodialysis patients

BACKGROUND

Sudden cardiac death is the leading cause of cardiac-related death in hemodialysis patients. Hypotensive episodes in pre-, intra-, and post-dialytic periods can present serious clinical challenges that affect a patient's quality of life and prognosis. The aim of the present study was to evaluate cardiac autonomic control and arrhythmogenic risk by analyzing 24-h heart rate variability (HRV) and heart rate turbulence (HRT) in hypotensive hemodialysis patients.

METHODS

A total of 79 patients on maintenance hemodialysis treatment, 39 normotensive and 40 with frequent hypotension episodes during non-dialysis periods, were included in the study. Dialysis-free periods were recorded with a 24-h Holter rhythm and ambulatory blood pressure monitor device. The time-domain parameters of HRV and HRT, including turbulence onset (TO) and turbulence slope (TS), were calculated.

RESULTS

Values for SDNN (105.5 ± 7.02, 127.6 ± 6.2 p < 0.001), SDANN (95.1 ± 5.9, 111.8 ± 5.01 p < 0.001), and SDNN index (50.04 ± 2.7, 55.6 ± 3.7 p = 0.03), in the hypotensive group were significantly lower than in the normotensive group, respectively. Values for RMSSD (26.5 ± 2.5, 27.3 ± 2.7 p = 0.178), pNN50 (17 ± 1.7, 55.6 ± 3.7 p = 0.03), and Tİ (35.1 ± 3.1, 34.7 ± 2.6 p = 0.542) in both groups were not significantly different; however, there was a significant difference between HRT parameters, TO (- 1.8 ± 0.37, - 2.4 ± 0.39 p < 0.001) and TS (6.9 ± 0.71, 8.2 ± 0.97 p < 0.001), respectively, hypotensive and normotensive group.

CONCLUSION

Dialysis patients that experience frequent hypotensive episodes may also undergo significant changes in HRT and HRV which may be indicative of serious cardiac sequela. Thus, in such cases, a complete cardiologic evaluation is warranted.

The effects of acetylcholinesterase inhibitors on the heart in acute myocardial infarction and heart failure: From cells to patient reports

Cardiovascular diseases remain a major cause of morbidity and mortality worldwide. Cardiovascular diseases such as acute myocardial infarction, ischaemia/reperfusion injury and heart failure are associated with cardiac autonomic imbalance characterized by sympathetic overactivity and parasympathetic withdrawal from the heart. Increased parasympathetic activity by electrical vagal nerve stimulation has been shown to provide beneficial effects in the case of cardiovascular diseases in both animals and patients by improving autonomic function, cardiac remodelling and mitochondrial function. However, clinical limitations for electrical vagal nerve stimulation exist because of its invasive nature, costly equipment and limited clinical validation. Therefore, novel therapeutic approaches which moderate parasympathetic activities could be beneficial for in the case of cardiovascular disease. Acetylcholinesterase inhibitors inhibit acetylcholinesterase and hence increase cholinergic transmission. Recent studies have reported that acetylcholinesterase inhibitors improve autonomic function and cardiac function in cardiovascular disease models. Despite its potential clinical benefits for cardiovascular disease patients, the role of acetylcholinesterase inhibitors in acute myocardial infarction and heart failure remediation remains unclear. This article comprehensively reviews the effects of acetylcholinesterase inhibitors on the heart in acute myocardial infarction and heart failure scenarios from in vitro and in vivo studies to clinical reports. The mechanisms involved are also discussed in this review.

Lower Systolic Blood Pressure in Normotensive Subjects is Related to Better Autonomic Recovery Following Exercise

Blood pressure (BP) is a cardiovascular parameter applied to detect cardiovascular risk. Recently, the pre-hypertension state has received greater consideration for prevention strategies. We evaluated autonomic and cardiorespiratory recovery following aerobic exercise in normotensive individuals with different systolic BP (SBP) values. We investigated 30 healthy men aged 18 to 30 years divided into groups according to systolic BP (SBP): G1 (n = 16), resting SBP <110 mmHg and G2 (n = 14), resting SBP between 120-110 mmHg. The groups endured 15 minutes seated at rest, followed by a submaximal aerobic exercise on a treadmill and then remaining seated for 60 minutes also at rest, during recovery from the exercise. Cardiorespiratory parameters and heart rate (HR) variability (HRV) (rMSSD, SD1, HF [ms2]) were evaluated before and during recovery from exercise. G2 displayed slower return of SBP, rMSSD and SD1 HRV indices during recovery from exercise compared to G1. In conclusion, normotensive subjects with higher resting SBP (110 to 120 mmHg) offered delayed autonomic recovery following moderate exercise. We suggest that this group may be less physiologically optimized leading to cardiac risks.

Lower cardiovagal tone and baroreflex sensitivity associated with hepatic insulin resistance and promote cardiovascular disorders in Tibetan minipigs induced by a high fat and high cholesterol diet

AIMS

A long-term high-fat/cholesterol (HFC) diet leads to hepatic insulin resistance (IR), which is associated with autonomic dysfunction and cardiovascular diseases risk increasing. However, whether this occurs in Tibetan minipigs remains unknown. We tested that a long-term HFC diet caused hepatic IR and promote cardiovascular disorders in Tibetan minipigs, and are associated with the reduction of cardiovagal tone and baroreflex sensitivity (BRS).

METHODS

Male Tibetan minipigs were fed either a standard diet or a HFC diet, and were euthanized at 12 weeks. Thereafter, the minipigs were tested for biochemical blood indices, glucose tolerance, blood pressure, heart rate variability (HRV), BRS, and insulin receptor substrate (IRS)-associated gene and protein expression levels, as well as cardiac function.

RESULTS

HFC-fed minipigs developed IR by increasing body weight, total cholesterol, fasting blood glucose and insulin levels, and nonesterified fatty acid (NEFA) and high sensitive C-reactive protein (hs-CRP) levels, glucose intolerance. Increased adipose cell size, hepatic fat deposition, malondialdehyde (MDA) content and NEFA level, down-regulation of IRS1, IRS2, PI3K, Akt, p-Akt, Glut2 and PGC1ɑ expression concomitant with up-regulation of mTOR, GSK3β, TNF-ɑ, FOXO1, p-mTOR and p-p70S6K expression in the liver tissue, as well as hypertension and left ventricular diastolic dysfunction were observed in HFC-fed minipigs. HRV parameters and BRS values were further significantly reduced. Furthermore, multiple linear regression analysis showed that the development of hepatic IR toward cardiovascular disease was associated with low HFnu, RMSSD, BRS and LV -dp/dtmax, high NEFA, high hepatic TG content.

CONCLUSION

These data suggest that HFC-fed Tibetan minipigs develop hepatic IR and promote cardiovascular disorders, and are associated with lower cardiovagal tone and BRS.

Gut microbiota and inflammation in chronic kidney disease and their roles in the development of cardiovascular disease

The health and proper functioning of the cardiovascular and renal systems largely depend on crosstalk in the gut-kidney-heart/vessel triangle. Recent evidence suggests that the gut microbiota has an integral function in this crosstalk. Mounting evidence indicates that the development of chronic kidney and cardiovascular diseases follows chronic inflammatory processes that are affected by the gut microbiota via various immune, metabolic, endocrine, and neurologic pathways. Additionally, deterioration of the function of the cardiovascular and renal systems has been reported to disrupt the original gut microbiota composition, further contributing to the advancement of chronic cardiovascular and renal diseases. Considering the interaction between the gut microbiota and the renal and cardiovascular systems, we can infer that interventions for the gut microbiota through diet and possibly some medications can prevent/stop the vicious cycle between the gut microbiota and the cardiovascular/renal systems, leading to a decrease in chronic cardiovascular and renal diseases.

Sympathovagal imbalance and neurophysiologic cognitive assessment using evoked potentials in polycystic ovary syndrome in young adolescents - a cross-sectional study

Background Altered lifestyle and urbanization have potentially increased the prevalence of polycystic ovary syndrome (PCOS) among the women in India. The aim of the present study was to evaluate the autonomic function and subclinical cognition impairment using evoked potentials in PCOS-affected young adolescents. Methods This was a cross-sectional study, approved by Indian Medical of Council Research as a short-term student project. The study was performed with adolescent girls (age group, 10-18 years) diagnosed as having PCOS, attending the Department of Obstetrics and Gynecology at Sri Manakula Vinayagar Medical College and Hospital, Puducherry. Autonomic function was evaluated using heart rate variability and cognition employing auditory evoked potentials (P300 latency and amplitude) among the control group (n=30) and the PCOS group (n=30). Results Our study reports indicated that autonomic functions were significantly affected among the PCOS group compared to the control group (p=0.03), with sympathetic dominance and decreased vagal tone. P300 latency was prolonged and amplitude was decreased among the PCOS group, but the results were not statistically significant when compared to the control group. Body mass index showed significant correlation with sympathovagal imbalance. Conclusion The study indicates that autonomic functions are significantly altered in the PCOS group. Subclinical cognition impairment is seen among the PCOS group but is not pronounced enough to be proven statistically. This study informs adolescent girls to make early lifestyle changes as soon as possible before any significant clinical impairment occurs.

Fetal-growth-restricted preterm infants display compromised autonomic cardiovascular control on the first postnatal day but not during infancy

BackgroundFetal growth restriction (FGR) is associated with increased perinatal mortality and long-term cardiovascular and neurodevelopmental sequelae. We hypothesized that FGR impacts on the development of autonomic heart rate and blood pressure control, contributing to unfavorable short- and long-term outcomes following FGR.MethodsWe studied 25 preterm FGR and 22 preterm and 19 term appropriate for gestational age (AGA) infants. Preterm neonates were studied on postnatal day 1, and all infants were studied at 1 and 6 months post-term age. To investigate autonomic cardiovascular control, we examined heart rate variability (HRV) and baroreflex sensitivity using spectral power and transfer-function analyses.ResultsPreterm FGR neonates exhibited higher heart rates and reduced HRV compared with preterm AGA controls on postnatal day 1. No significant differences were found between the three groups at 1 or 6 months post-term age.ConclusionPreterm FGR neonates display compromised HRV on postnatal day 1, which may suggest increased vulnerability to circulatory instability. This may predispose these neonates to systemic and cerebral hypoperfusion and increase the risk of long-term neurodevelopmental sequelae. Differences were no longer found at 1 and 6 months post-term age, suggesting that the maturation of autonomic cardiovascular control may be preserved following FGR.

Effect of 12 Weeks of Yoga Therapy on Quality of Life and Indian Diabetes Risk Score in Normotensive Indian Young Adult Prediabetics and Diabetics: Randomized Control Trial

Introduction

India has become the epicentre for diabetes, a stress-related disorder affecting the working skills and day-to-day lifestyle management of younger population. Most of the studies have reported the effect of yoga on improving Quality of Life (QoL) in diabetic patients with other comorbidities. Till date, no randomized control trial reports are available to show the effect of yoga therapy on QoL and Indian Diabetes Risk Score (IDRS) in normotensive prediabetic and diabetic young individuals.

Aim

To determine the effect of 12 weeks of yoga therapy on QoL and IDRS among normotensive prediabetic and diabetic young Indian adults.

Materials and Methods

A randomized control trial was conducted in Endocrinology Outpatient Department (OPD). Normotensive participants (n=310) aged 18-45 years were divided into healthy controls (n=62), prediabetics (n=124) and diabetics (n=124). Study group subjects were randomly assigned to Group II (n=62, prediabetes-standard treatment), Group III (n=62, prediabetes-standard treatment + yoga therapy), Group IV (n=62, diabetes-standard treatment) and Group V (n=62, diabetes-standard treatment + yoga therapy). Flanagan QoL scale, IDRS questionnaire, Fasting Plasma Glucose (FPG) and insulin were assessed pre and post 12 weeks of intervention. Statistical analysis was done using Student's paired t-test and one-way ANOVA.

Results

Pre-post intervention analysis showed significant improvement in QoL scale with p<0.01 in Group II and Group IV; p<0.001 in Group III and Group V respectively. There was significant reduction in IDRS in Group II (p<0.05); p<0.001 in Group III, Group IV and Group V respectively. Significant difference (p<0.001) in QoL scale and IDRS were found when study groups with standard treatment along with yoga therapy were compared to standard treatment alone.

Conclusion

Yoga therapy along with standard treatment for 12 weeks improved QoL and attenuated the diabetes risk among Indian prediabetics and diabetics compared to standard treatment alone.

Decreased baroreflex sensitivity is linked to the atherogenic index, retrograde inflammation, and oxidative stress in subclinical hypothyroidism

Purpose/aim of the study: The present study investigated the link of hyperlipidemia, inflammation and oxidative stress (OS) to cardiovascular (CV) risks in subclinical hypothyroidism (SCH).

MATERIALS AND METHODS

We enrolled 81 subclinical hypothyroid patients and 80 healthy subjects as control. Their CV and autonomic functions were assessed by spectral analysis of heart rate variability (HRV), continuous blood pressure variability (BPV) measurement and conventional autonomic function testing. Thyroid profile, lipid profile, immunological, inflammatory and OS markers were estimated and correlated with the baro-reflex sensitivity (BRS), the marker of sympathovagal imbalance (SVI) & CV risk.

RESULTS

Mean arterial pressure (MAP, P<0.0001), total peripheral resistance (TPR, P<0.0001), ratio of low-frequency to high-frequency power of HRV (LF-HF ratio) (P<0.0001) were significantly higher and BRS (P<0.0001) was significantly lower in SCH group than the control group. BRS significantly correlated with heart rate, MAP, LF-HF ratio, lipid risk factors, anti-thyroperoxidase antibody, thyroid-stimulating hormone, high-sensitive C-reactive protein (hsCRP), malondialdehyde (MDA) and SCH.

CONCLUSIONS

It was concluded that SVI is associated with SCH. Though dyslipidemia, inflammation and OS contributed to decreased BRS, SCH per se contributed maximally to it. Decreased BRS could be a physiological basis of increased CV risks in patients with SCH.

Endothelial nitric oxide synthase gene polymorphisms are associated with cardiovascular risks in prehypertensives

Though endothelial nitric oxide synthase (eNOS) gene polymorphism is documented in the causation of hypertension, its role in prehypertension has not been investigated. The present study was conducted in 172 subjects divided into prehypertensives (n = 57) and normotensives (n = 115). Cardiovascular (CV) parameters including baroreflex sensitivity (BRS) by continuous BP variability assessment and sympathovagal imbalance (SVI) by heart rate variability analysis were recorded. Biochemical parameters for insulin resistance (homeostatic model for assessment of insulin resistance), oxidative stress, lipid risk factors, renin, and inflammatory parameters were measured. Genotyping for eNOS polymorphisms rs1799983 (298G>T) and rs2070744 (-786T>C) was performed by polymerase chain reaction-restriction fragment length polymorphism method. Multiple regression analysis was done to assess the association between SVI and metabolic markers, and multivariate logistic regression was done to determine the prediction of prehypertension status by genotype, BRS, and ratio of low-frequency to high-frequency in these subjects. The BP variability, heart rate variability, and biochemical parameters were significantly altered in prehypertensives. The eNOS polymorphisms were found to be associated with prehypertension. BRS, the marker of SVI, was significantly associated with BP, homeostatic model for assessment of insulin resistance, and tumor necrosis factor alpha in 298GG genotype of prehypertensive population. The eNOS gene polymorphisms appear to be associated with prehypertension. 298G>T and -786T>C contribute to SVI in young prehypertensives attributed by insulin resistance and inflammation. The CV risks were associated with prehypertension status in prehypertensives expressing both 298GG and -786TT genotypes. Association of CV risks with SVI appears to be stronger in prehypertensives expressing GG genotype.

Attenuated Heart Rate Recovery After Exercise Testing and Risk of Incident Hypertension in Men

BACKGROUND

Although attenuated heart rate recovery (HRR) and reduced heart rate (HR) reserve to maximal exercise testing are associated with adverse cardiovascular outcomes, their relation to incident hypertension in healthy normotensive populations is unclear. We examined the hypothesis that both attenuated HRR and reduced HR reserve to exercise testing are associated with incident hypertension in men.

METHODS

A total of 1,855 participants were selected comprising of healthy, initially normotensive men who underwent peak or symptom-limited treadmill testing at baseline. HRR was calculated as the difference between peak HR during exercise testing and the HR at 2 minutes after exercise cessation. HR reserve was calculated as the percentage of HR reserve (peak HR - resting HR)/(220 - age - resting HR) × 100.

RESULTS

During an average 4-year follow-up, 179 (9.6%) men developed hypertension. Incident hypertension was associated with HRR quartiles (Q1 (<42 (bpm)) 12.5%, Q2 (43-49 bpm) 8.5%, Q3 (50-56 bpm) 9.3%, and Q4 (>57 bpm) 8.3%; P = 0.05 for trend). The relative risk (RR) of the incident hypertension in the slowest HRR quartile vs. the fastest HRR quartile was 1.78 (95% confidence interval (CI): 1.14-2.78) after adjustment for confounders. Every 1 bpm increment in HRR was associated with a 2% (RR 0.98, 95% CI: 0.97-0.99) lower risk of incident hypertension after adjusting for potential confounders. In contrast, reduced HR reserve did not predict the risk of incident hypertension.

CONCLUSIONS

Slow HRR after exercise testing is independently associated with the development of hypertension in healthy normotensive men.

Intrauterine growth restriction: impact on cardiovascular development and function throughout infancy

Intrauterine growth restriction (IUGR) refers to the situation where a fetus does not grow according to its genetic growth potential. One of the main causes of IUGR is uteroplacental vascular insufficiency. Under these circumstances of chronic oxygen and nutrient deprivation, the growth-restricted fetus often displays typical circulatory changes, which in part represent adaptations to the suboptimal intrauterine environment. These fetal adaptations aim to preserve oxygen and nutrient supply to vital organs such as the brain, the heart, and the adrenals. These prenatal circulatory adaptations are thought to lead to an altered development of the cardiovascular system and "program" the fetus for life long cardiovascular morbidities. In this review, we discuss the alterations to cardiovascular structure, function, and control that have been observed in growth-restricted fetuses, neonates, and infants following uteroplacental vascular insufficiency. We also discuss the current knowledge on early life surveillance and interventions to prevent progression into chronic disease.

Attenuated baroreflex sensitivity in normotensive prediabetes and diabetes in Indian adults

PURPOSE/AIM OF THE STUDY

Though attenuated baroreflex sensitivity (BRS) is known to promote cardiovascular disease (CVD) risk in diabetics, its status in prediabetes has not been reported. Also, the link of BRS to CVD risk in normotensive diabetics has not been reported. This study aimed to evaluate the association of BRS to CVD risk in normotensive prediabetics and diabetics.

MATERIALS AND METHODS

Participants (n = 154) of 18-45 years were divided into normoglycemics (n = 52), prediabetics (n = 64) and diabetics (n = 38) based on American Diabetes Association criteria. Body mass index, waist-hip ratio, waist-height ratio, body fat mass index, basal heart rate, systolic blood pressure, diastolic blood pressure, rate pressure product, BRS, heart rate variability (HRV), fasting plasma glucose, fasting insulin, lipid profile and atherogenic index of plasma (AIP) were measured. Indian Diabetes Risk Score (IDRS) and homeostatic model assessment of insulin resistance were calculated.

RESULTS

There was significant increase in all the parameters except BRS, HRV and high-density lipoprotein in prediabetics and diabetics compared to normoglycemics. All these parameters were significantly altered in prediabetics compared to diabetics. Significant negative correlation was found between BRS and other parameters in prediabetics and diabetics.

CONCLUSIONS

BRS was attenuated in normotensive prediabetics and diabetics with high IDRS, insulin resistance, AIP, dyslipidemia and reduced HRV that predisposes them to CVD risk. The study demonstrates CVD risk quite early in the prediabetics with reduced HRV, high body fat, hyperinsulinemia, insulin resistance, AIP and rate pressure product.

Cardiovascular Autonomic Dysfunction in Chronic Kidney Disease: a Comprehensive Review

Cardiovascular autonomic dysfunction is a major complication of chronic kidney disease (CKD), likely contributing to the high incidence of cardiovascular mortality in this patient population. In addition to adrenergic overdrive in affected individuals, clinical and experimental evidence now strongly indicates the presence of impaired reflex control of both sympathetic and parasympathetic outflow to the heart and vasculature. Although the principal underlying mechanisms are not completely understood, potential involvements of altered baroreceptor, cardiopulmonary, and chemoreceptor reflex function, along with factors including but not limited to increased renin-angiotensin-aldosterone system activity, activation of the renal afferents and cardiovascular structural remodeling have been suggested. This review therefore analyzes potential mechanisms underpinning autonomic imbalance in CKD, covers results accumulated thus far on cardiovascular autonomic function studies in clinical and experimental renal failure, discusses the role of current interventional and therapeutic strategies in ameliorating autonomic deficits associated with chronic renal dysfunction, and identifies gaps in our knowledge of neural mechanisms driving cardiovascular disease in CKD.

Novel strategies and underlying protective mechanisms of modulation of vagal activity in cardiovascular diseases

Cardiovascular disease remains a major cause of disability and death worldwide. Autonomic imbalance, characterized by suppressed vagal (parasympathetic) activity and increased sympathetic activity, correlates with various pathological conditions, including heart failure, arrhythmia, ischaemia/reperfusion injury and hypertension. Conventionally, pharmacological interventions, such as β-blocker treatment, have primarily targeted suppressing sympathetic over-activation, while vagal modulation has always been neglected. Emerging evidence has documented the improvement of cardiac and vascular function mediated by the vagal nerve. Many investigators have tried to explore the effective ways to enhance vagal tone and normalize the autonomic nervous system. In this review, we attempt to give an overview of these therapeutic strategies, including direct vagal activation (electrical vagal stimulation, ACh administration and ACh receptor activation), pharmacological modulation (adenosine, cholinesterase inhibitors, statins) and exercise training. This overview provides valuable information for combination therapy, contributing to establishment of a comprehensive system on vagal modulation from the aspects of clinical application and lifestyle improvement. In addition, the mechanisms contributing to the benefits of enhancing vagal tone are diverse and have not yet been fully defined. We endeavour to outline the recent findings that advance our knowledge regarding the many favourable effects exerted by vagal activation: anti-inflammatory pathways, modulation of NOS and NO signalling, regulation of redox state, improvement of mitochondrial biogenesis and function, and potential calcium regulation. This review may help to develop novel therapeutic strategies targeting enhancing vagal activity for the treatment of cardiovascular diseases.

Association of sympathovagal imbalance with cardiovascular risks in patients with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is associated with cardiovascular risks like obesity, insulin resistance, dyslipidemia that can lead to sympathovagal imbalance (SVI). The study was designed to assess the cardiovascular risk in PCOS and link of metabolic derangements to SVI. Thirty-five newly diagnosed PCOS patients and 32 age-matched controls were recruited. Waist-hip ratio, body mass index (BMI), basal cardiovascular parameters such as basal heart rate (BHR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and rate pressure product (RPP) were recorded. Autonomic functions were assessed using short-term heart rate variability (HRV) analysis, heart rate and blood pressure response to standing (30:15 ratio), deep breathing (E:I ratio) and isometric handgrip (ΔDBPihg). Fasting plasma glucose, insulin, lipid profile and testosterone were assayed. Insulin resistance (HOMA-IR) and lipid risk factors were calculated. The cases had increased BHR, BMI, SBP, DBP, MAP and RPP. The ratio of low-frequency to high-frequency (LF-HF) of HRV, the marker of SVI was significantly increased in cases. 30:15 ratio and ΔDBPihg were increased and E:I ratio was decreased in the cases. HOMA-IR, lipid risk factors and testosterone were significantly elevated in cases. There was a significant correlation of LF-HF with BMI, BHR, RPP, insulin resistance and lipid risk factors. On regression analysis, insulin resistance and lipid risk factors had independent association with LF-HF. PCOS patients have SVI, decreased HRV and increased RPP and the potential cardiovascular risks. The insulin resistance and dyslipidemia contribute to SVI and cardiovascular risks in PCOS patients.

The Effects of Short-Term Relaxation Therapy on Indices of Heart Rate Variability and Blood Pressure in Young Adults

Purpose.

Assessment of short-term practice of relaxation therapy on autonomic and cardiovascular functions in first-year medical students.

Design.

Case-control, interventional study.

Setting.

Medical college laboratory.

Subjects.

Sixty-seven medical students, divided into two groups: study group (n = 35) and control group (n = 32).

Intervention.

Study group subjects practiced relaxation therapy (shavasana with a soothing background music) daily 1 hour for 6 weeks. Control group did not practice relaxation techniques.

Measures.

Cardiovascular parameters and spectral indices of heart rate variability (HRV) were recorded before and after the 6-week practice of relaxation therapy.

Analysis.

The data between the groups and the data before and after practice of relaxation techniques were analyzed by one-way analysis of variance and Student t-test. In the study group, prediction of low-frequency to high-frequency ratio (LF-HF) of HRV, the marker of sympathovagal balance, to blood pressure (BP) status was assessed by logistic regression.

Results.

In the study group, there was significant reduction in heart rate (p = .0001), systolic (p = .0010) and diastolic (p = .0021) pressure, and rate pressure product (p < .0001), and improvement in HRV indices, following 6 weeks of relaxation therapy. As determined by regression model, prediction of LF-HF to BP status was more significant (odds ratio, 2.7; p = .009) after practice of relaxation therapy. There was no significant alteration in these parameters in control subjects.

Conclusion.

Short-term practice of relaxation therapy can improve autonomic balance and promote cardiovascular health of medical students. Sympathovagal balance is directly linked to BP status in these individuals.

The Relationship between Serum Lipid Fractions and Heart Rate Variability in Diabetic Patients with Statin Therapy

BACKGROUND AND AIMS

The aim of this study is to identify and highlight the relationship between serum lipid fractions and heart rate variability in diabetic patients receiving statin therapy.

PATIENTS AND METHODS

The study was performed in a group of 87 type 2 diabetic patients on statin associated therapy. All patients were on Holter ECG 24 hours monitored with three channel monitor (Labtech ECG Holter monitor), and data were analyzed on a commercially available software (Cardiospy PC SW/EV 5.02.06.02). Concentrations of biochemical parameters were determined using specific enzymatic assays on an autoanalyzer Olympus AU 680. In the studied patients, we analyzed Holter/24 hours monitoring reports with respect to heart rate variability indexes, arrhythmic events and myocardial ischemia.

RESULTS

It was noticed that the mean values of serum TG were slightly elevated, TC levels were close to the limits specified by the guidelines for diabetic patients and for patients with cardiovascular diseases, with no significant differences between males and females. After analyzing the HRV in both time and frequency domains, we found no strong correlations between any of the HRV indexes and any of the lipid fractions.

CONCLUSIONS

The results suggest that statin therapy may reduce the autonomic impairment secondary to dyslipidemia.

Association of hypertension status and cardiovascular risks with sympathovagal imbalance in first degree relatives of type 2 diabetics

AIMS/INTRODUCTION

As reports show cardiovascular (CV) risks in first-degree relatives (FDR) of type 2 diabetics, and autonomic imbalance predisposing to CV risks, in the present study we have assessed the contribution of sympathovagal imbalance (SVI) to CV risks in these subjects.

MATERIALS AND METHODS

Body mass index (BMI), waist-to-hip ratio (WHR), basal heart rate (BHR), blood pressure (BP), rate pressure product (RPP), and spectral indices of heart rate variability (HRV) were reordered and analyzed in FDR of type 2 diabetics (study group, n = 293) and in subjects with no family history of diabetes (control group, n = 405).

RESULTS

The ratio of low-frequency (LF) to high-frequency (HF) power of HRV (LF-HF), a sensitive marker of SVI, was significantly increased (P < 0.001) in the study group compared with the control group. The SVI in the study group was due to concomitant sympathetic activation (increased LF) and vagal inhibition (decreased HF). In the study group, the LF-HF ratio was significantly correlated with BMI, WHR, BHR, BP and RPP. Multiple regression analysis showed an independent contribution of LF-HF to hypertension status (P = 0.000), and bivariate logistic regression showed significant prediction (odds ratio 2.16, confidence interval 1.130-5.115) of LF-HF to increased RPP, the marker of CV risk, in the study group.

CONCLUSIONS

Sympathovagal imbalance in the form of increased sympathetic and decreased parasympathetic activity is present in FDR of type 2 diabetics. Increased resting heart rate, elevated hypertension status, decreased HRV and increased RPP in these subjects make them vulnerable to CV risks. SVI in these subjects contributes to CV risks independent of the degree of adiposity.

Slow yogic breathing through right and left nostril influences sympathovagal balance, heart rate variability, and cardiovascular risks in young adults

Background:

Specific nostril breathing is known to influence autonomic functions.

Aim:

The study was to assess the effects of right nostril breathing (RNB) and left nostril breathing (LNB) on heart rate variability (HRV) and cardiovascular functions.

Material and Methods:

Eighty-five student volunteers were divided into three groups: RNB group (n = 30), LNB group (n = 30), and control group (n = 25). RNB and LNB group subjects practiced right and left nostril breathing, respectively, every day 1 h for 6 weeks. The control group did not practice nostril breathing. Cardiovascular parameters and spectral indices of HRV were recorded before and after 6-week practice of nostril breathing. In RNB and LNB groups, prediction of rate-pressure product (RPP) by low-frequency to high-frequency ratio (LF-HF) of HRV was assessed by bivariate logistic regression.

Results:

HRV indices representing sympathetic activity were increased in the RNB group and indices representing parasympathetic activity were increased in LNB group following 6-week nostril breathing. Prediction of LF-HF to RPP, the marker of cardiovascular risks, was more significant (OR 2.65, P = 0.005) in the LNB group compared to the RNB group (OR 1.452, P = 0.016).

Conclusions:

Short-term practice of LNB improves vagal tone, increases HRV, and promotes cardiovascular health of medical students. Practice of RNB increases sympathetic tone and could jeopardize cardiovascular health.

Effects of gender on sympathovagal imbalance, prehypertension status, and cardiovascular risks in first-degree relatives of type 2 diabetics

BACKGROUND

Although cardiovascular (CV) risks are reported in first-degree relatives (FDRs) of type 2 diabetics, effects of gender on sympathovagal imbalance (SVI) and CV risks in these subjects have not been investigated.

METHODS

Body mass index (BMI), blood pressure variability parameters including baroreflex sensitivity (BRS), spectral indices of heart rate variability, autonomic function tests, insulin resistance, lipid profile, inflammatory markers (interleukin 6, high-sensitivity C-reactive protein, tumor necrosis factor α) and oxidative stress (OS) marker were measured and analyzed in control group (without family history of diabetes; 65 women, 60 men) and study group (FDRs of type 2 diabetics; 52 women, 49 men) subjects.

RESULTS

BMI, heart rate, blood pressure, rate-pressure product, stroke volume, left-ventricular ejection time, cardiac output, total peripheral resistance, homeostatic model of insulin resistance, lipid profile, inflammatory and OS markers, and ratio of low-frequency to high-frequency power of heart rate variability (LF-HF ratio), a sensitive marker of SVI, were significantly increased, and BRS was significantly decreased in study group men compared with women. SVI was more intense in men and was due to concomitant sympathetic activation and vagal inhibition. There was no SVI in control subjects. Multiple regression analysis demonstrated independent contribution of BMI, homeostatic model of insulin resistance, atherogenic index, inflammatory and OS markers, and BRS to LF-HF ratio. Logistic regression analysis demonstrated significant prediction of prehypertension status and rate-pressure product (markers of CV risk) by LF-HF, which was more prominent in men.

CONCLUSIONS

SVI is more intense in male FDRs of type 2 diabetics, and SVI is associated with increased CV risk due to insulin resistance, dyslipidemia, inflammation, and oxidative stress in these subjects.

Association of sympathovagal imbalance with cardiovascular risks in young prehypertensives

Although cardiovascular (CV) risks have been reported in prehypertension, their link to sympathovagal imbalance (SVI) has not been investigated. In the present study, we have assessed the factors contributing to SVI and the prediction of CV risk by SVI in prehypertensives. Body mass index, CV parameters such as heart rate, systolic blood pressure (BP), diastolic BP, mean arterial pressure, rate-pressure product (RPP), stroke volume, left ventricular ejection time, cardiac output, total peripheral resistance, baroreflex sensitivity recorded by continuous blood pressure variability monitoring using Finapres, autonomic function tests recorded by spectral analysis of heart rate variability (HRV), and heart rate and BP responses to standing, deep breathing, and isometric handgrip, and biochemical parameters such as homeostatic model assessment of insulin resistance, lipid risk factors, inflammatory markers, thyroid profile, and renin and oxidative stress parameters were analyzed in young normotensives (n = 118) and prehypertensives (n = 58). Contribution of CV risks to low-frequency/high-frequency (LF/HF) ratio of HRV, the marker of SVI, was determined by multiple regression analysis, and prediction of SVI to RPP, a known CV risk, was assessed by logisitic regression adjusted for body mass index. BP variability, HRV, and autonomic function test parameters were significantly altered in prehypertensives and these parameters were correlated with LF/HF. Insulin resistance, dyslipidemia, inflammation, and oxidative stress contributed to SVI in prehypertensives. LF/HF and baroreflex sensitivity had significant prediction of RPP in prehypertensives. In conclusion, SVI in young prehypertensives is due to both increased sympathetic and decreased vagal tone. CV risks are linked to SVI and SVI predicts cardiac risk in prehypertensives.

Association of sympathovagal imbalance with cardiovascular risks in overt hypothyroidism

Background:

Cardiovascular morbidities have been reported in hypothyroidism.

Aims:

The objective of this study is to investigate the link of sympathovagal imbalance (SVI) to cardiovascular risks (CVRs) and the plausible mechanisms of CVR in hypothyroidism.

Materials and Methods:

Age-matched 104 females (50 controls, 54 hypothyroids) were recruited and their body mass index (BMI), cardiovascular parameters, autonomic function tests by spectral analysis of heart rate variability (HRV), heart rate response to standing, deep breathing and blood pressure response to isometric handgrip were studied. Thyroid profile, lipid profile, immunological and inflammatory markers were estimated and their association with low-frequency to the high-frequency ratio (LF-HF) of HRV, the marker of SVI was assessed by multivariate regression.

Results:

Increased diastolic pressure, decreased HRV, increased LF-HF, dyslipidemia and increased high-sensitive C-reactive protein (hsCRP) were observed in hypothyroid patients and all these parameters had significant correlation with LF-HF. BMI had no significant association with LF-HF. Atherogenic index (β 1.144, P = 0.001) and hsCRP (b 0.578, P = 0.009) had independent contribution to LF-HF. LF-HF could significantly predict hypertension status (odds ratio 2.05, confidence interval 1.110-5.352, P = 0.008) in hypothyroid subjects.

Conclusions:

SVI due to sympathetic activation and vagal withdrawal occurs in hypothyroidism. Dyslipidemia and low-grade inflammation, but not obesity contribute to SVI and SVI contributes to cardiovascular risks.

Sympathovagal imbalance contributes to prehypertension status and cardiovascular risks attributed by insulin resistance, inflammation, dyslipidemia and oxidative stress in first degree relatives of type 2 diabetics

BACKGROUND

Though cardiovascular (CV) risks are reported in first-degree relatives (FDR) of type 2 diabetics, the pathophysiological mechanisms contributing to these risks are not known. We investigated the association of sympathovagal imbalance (SVI) with CV risks in these subjects.

SUBJECTS AND METHODS

Body mass index (BMI), basal heart rate (BHR), blood pressure (BP), rate-pressure product (RPP), spectral indices of heart rate variability (HRV), autonomic function tests, insulin resistance (HOMA-IR), lipid profile, inflammatory markers, oxidative stress (OS) marker, rennin, thyroid profile and serum electrolytes were measured and analyzed in subjects of study group (FDR of type 2 diabetics, n = 72) and control group (subjects with no family history of diabetes, n = 104).

RESULTS

BMI, BP, BHR, HOMA-IR, lipid profile, inflammatory and OS markers, renin, LF-HF (ratio of low-frequency to high-frequency power of HRV, a sensitive marker of SVI) were significantly increased (p<0.0001) in study group compared to the control group. SVI in study group was due to concomitant sympathetic activation and vagal inhibition. There was significant correlation and independent contribution of markers of insulin resistance, dyslipidemia, inflammation and OS to LF-HF ratio. Multiple-regression analysis demonstrated an independent contribution of LF-HF ratio to prehypertension status (standardized beta 0.415, p<0.001) and bivariate logistic-regression showed significant prediction (OR 2.40, CI 1.128-5.326, p = 0.002) of LF-HF ratio of HRV to increased RPP, the marker of CV risk, in study group.

CONCLUSION

SVI in FDR of type 2 diabetics occurs due to sympathetic activation and vagal withdrawal. The SVI contributes to prehypertension status and CV risks caused by insulin resistance, dyslipidemia, inflammation and oxidative stress in FDR of type 2 diabetics.

Assessment of cardiovascular autonomic function in patients with polycystic ovary syndrome

AIM

The study was conducted to assess the sympathovagal balance in patients with polycystic ovary syndrome (PCOS) using short-term heart rate variability (HRV) analysis and conventional autonomic function tests (CAFT).

METHODS

Thirty-one newly diagnosed patients with PCOS and 30 age-matched controls were recruited. Body mass index (BMI), waist : hip ratio (WHR), cardiovascular parameters such as basal heart rate (BHR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and rate-pressure product (RPP), and fasting blood glucose (FBG) were measured in both groups. Cardiovascular autonomic functions assessed were spectral analysis of HRV, heart rate and blood pressure response to standing (30:15 ratio), deep breathing (E:I ratio) and isometric handgrip (ΔDBP(ihg)).

RESULTS

The cases had significantly increased BMI, WHR, BHR, SBP, DBP and RPP. Ratio of low-frequency to high-frequency power of HRV (LF-HF ratio), the marker of sympathovagal balance was significantly increased in cases compared to controls. Time-domain indices of HRV and E:I ratio were decreased, and 30:15 ratio, ΔDBP(ihg) and FBG were increased in cases. Though there was a significant correlation of LF-HF ratio with BMI, WHR, BHR, RPP and FBG, only BHR and RPP had independent contribution to LF-HF ratio.

CONCLUSION

We conclude that PCOS patients have altered autonomic modulation in the form of increased sympathetic and decreased parasympathetic reactivity and HRV. The sympathovagal imbalance exposes them to cardiovascular morbidities.