Hyperuricemia is associated with sympathovagal imbalance in older adults

PurposeThis study aimed to compare heart rate variability (HRV) parameters obtained through symbolic analysis (SA), between older adults with and without hyperuricemia.MethodsThis is a cross-sectional study including 202 community-dwelling old adults, which was clinically stratified as with or without hyperuricemia, according to the cutoff point of serum uric acid ≥ 6 mg/dL for women and ≥ 7 mg/dL for men. Successive RR intervals were recorded along 5 min and analyzed with SA method. 0 V%, 1 V% and 2 V% patterns were quantified and compared between groups. Comparisons were carried out through parametric or nonparametric tests, according to the data distribution characteristics, evaluated by Kolmogorov-Smirnov test. The significance level was set as p ≤ 0.05 for all statistical procedures.ResultsThe prevalence of hyperuricemia was 67.8 %, and the hyperuricemic older adults exhibited significant higher values for V0% and lower values for V2% parameters when compared to normouricemic older adults.ConclusionThese results suggesting a sympathovagal imbalance in hyperuricemic older adults, characterized by greater sympathetic predominance (0 V%) and lower vagal modulation (2 V%) at rest conditions.     

Short‐term overt hypothyroidism induces sympathovagal imbalance in thyroidectomized differentiated thyroid carcinoma patients

Context Thyroid hormone impacts on the cardiovascular system. (Subclinical) hyperthyroidism results in sympathovagal imbalance due to decreased vagal tone. However, conflicting data have been reported on the effects of hypothyroidism on the activity of the autonomic nervous system (ANS). In hypothyroidism, both increased and decreased sympathetic activity and increased vagal tone have been found. Objective To study the effects of acute short‐term overt hypothyroidism and thyroxine replacement therapy on the ANS by measuring urinary excretion of catecholamines and heart rate variability (HRV). Design Prospective study. Setting University hospital. Patients We studied 11 patients, previously treated with thyroidectomy for differentiated thyroid carcinoma, during hypothyroidism caused by cessation of thyroxine substitution for 4 weeks and during thyroxine replacement therapy, and 21 matched healthy controls. Main outcome measures The activity of the ANS was assessed by measuring urinary excretion of catecholamines and HRV at rest and during a challenge of the ANS by a mental stress test. Results Urinary dopamine excretion was significantly lower during hypothyroidism. Although in the patients total variability was unchanged, HRV analysis showed a significantly lower low frequency/high frequency ratio, indicating sympathovagal imbalance with sympathetic withdrawal. The mental stress test in the patients resulted in a significant increase in heart rate to the extent of 16–18%. This response was not different between the hypothyroid state and during thyroxine replacement therapy suggesting that cardiovascular reflexes in these patients remain intact. Conclusion Acute short‐term overt hypothyroidism results in sympathovagal imbalance with sympathetic withdrawal, with preservation of the cardiovascular reflexes to (mental) stress.     

Spontaneous onset of torsade de pointes in long-QT syndrome and the role of sympathovagal imbalance.

The net effects of sympathetic and vagal activity on the QT interval and the mode of spontaneous onset of torsade de pointes (TdP) are still unclear in long-QT syndrome. Two patients with long-QT syndrome had syncope while undergoing Holter ECG investigation. The spontaneous onset of TdP in these patients was analyzed with respect to the relation between the RR and QT intervals. Both patients were high-school students (16- and 17-year-old boys) who had been diagnosed as long-QT syndrome and followed up without medical treatment because they had had neither a history of syncope nor arrhythmia induction by treadmill exercise tests. The first episode of syncope in both patients occurred during ordinary daily life and was not related to exercise or psychological stress. The dynamic changes between the RR and QT intervals associated with the spontaneous onset of TdP were analyzed by Holter ECG. Both patients showed sinus tachycardia followed by abrupt sinus bradycardia immediately before the onset of TdP. The enhanced rate of the adaptive response of the QT interval that occurred during the deceleration of the heart rate preceded the onset of TdP. These observations suggest that the complex situation that follows sympathovagal imbalance may have an important role in the dynamic change in the QT interval and initiation of TdP in patients with long-QT syndrome.     

Effect of supplementation of water-soluble vitamins on oxidative stress and blood pressure in prehypertensives

Abstract

The objective of the study was to evaluate the effect of water-soluble vitamins on oxidative stress and blood pressure in prehypertensives. Sixty prehypertensives were recruited and randomized into 2 groups of 30 each. One group received water-soluble vitamins and the other placebo for 4 months. Further increase in blood pressure was not observed in the vitamin group which increased significantly in the placebo group at the end of 4 months. Malonedialdehyde and protein carbonylation were reduced during the course of treatment with vitamins whereas in the placebo group there was an increase in the level of malondialdehyde. In conclusion, supplementation of water-soluble vitamins in prehypertension reduces oxidative stress and its progression to hypertension.     

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.     

Assessment of sympathovagal imbalance by spectral analysis of heart rate variability in prehypertensive and hypertensive patients in Indian population

Though the incidence of hypertension has increased considerably in recent years, the pathophysiologic mechanism that causes progression from stage of prehypertension to hypertension has not been fully elucidated. Therefore, the present study was conducted to assess the sympathovagal imbalance in prehypertensives and hypertensives by spectral analysis of heart rate variability (HRV) to understand the nature of change in autonomic balance in this common dysfunction of mankind. Body mass index (BMI), basal heart rate (BHR), blood pressure (BP), and spectral indices of HRV such as total power (TP), normalized low frequency power (LFnu), normalized high frequency power (HFnu), ratio of low frequency power to high frequency power (LF-HF ratio), mean heart rate (mean RR), square root of the mean squared differences of successive normal to normal intervals (RMSSD), the number of interval differences of successive NN intervals greater than 50 ms (NN50), and the proportion derived by dividing NN50 by the total number of NN intervals (pNN50) were assessed in three groups of subjects: normotensives (n = 32), prehypertensives (n = 28), and hypertensives (n = 31). Sympathovagal balance was analyzed and correlated with BMI, BHR, and BP in all the groups. It was observed that autonomic imbalance in prehypertensives was due to proportionate increased sympathetic activity and vagal inhibition, whereas in hypertensives, vagal withdrawal was more prominent than sympathetic overactivity. The LF-HF ratio, the sensitive indicator of sympathovagal balance, was significantly correlated with BMI, BHR, and BP. It was concluded that vagal inhibition plays an important role in the critical alteration of sympathovagal balance in the development of clinical hypertension in prehypertensive subjects.     

Prehypertension status,cardiometabolic risks,and decreased baroreflex sensitivity are linked to sympathovagal imbalance in salt-preferring individuals

Abstract

Salt preference has been reported to cause sympathovagal imbalance (SVI) and prehypertension. We investigated the role of inflammation, insulin resistance (IR), hyperlipidemia, and oxidative stress (OS) in genesis of SVI and cardiovascular (CV) risks in salt-preferring prehypertensives. The subjects were divided into no-salt-preferring (NSP, n?=?87) and salt-preferring (SP, n?=?89) group based on their preference for salted food. Body mass index (BMI), blood pressure (BP) variability parameters including baroreflex sensitivity (BRS), heart rate variability (HRV) indices, autonomic function tests, IR, lipid risk factors, inflammatory and OS markers, and renin were measured in both the groups. Based on the contribution of various cardiometabolic risks to low-frequency–high-frequency (LF–HF) ratio of HRV, the marker of SVI was assessed by multiple-regression analysis. Prediction of prehypertension status by the LF–HF ratio was assessed by bivariate logistic regression. BMI, heart rate, BP parameters, cardiac output, total peripheral resistance, LF–HF ratio, IR, atherogenic index, inflammatory, and OS markers were significantly increased, and BRS was significantly decreased in the SP group compared with the NSP group. There was an independent association of IR, atherogenic index, markers of inflammation and OS, and BRS with the LF–HF ratio in SP subjects, and the LF–HF ratio had significant prediction of prehypertension status in these subjects. It was concluded that IR, low-grade inflammation, atherogenic lipid profile, and OS contribute to SVI in SP subjects. Decreased BRS (the marker of CV risk) is linked to SVI, and SVI predicts prehypertension status in SP subjects.     

Effect of pioglitazone on cardiac sympathovagal modulation in patients with type 2 diabetes

This study aims to examine the effect of pioglitazone on potential progression of autonomic damage in addition to changes in control of cardiovascular function in patients with type 2 diabetes (T2DM). Thirty patients with T2DM and 32 healthy subjects participated in the study. Sympathovagal activity, assessed by power spectral analysis (PSA) of R–R intervals variability, and blood pressure (BP) were studied during clinostatism and orthostatism in controls and patients. We have assessed blood pressure control by 24-hour monitoring of ambulatory blood pressure. Patients were treated with pioglitazone (30 mg/day) for 6 months, and then re-evaluated by PSA for heart rate variability (HRV). Reduced levels of HbA1c (P < 0.0001) and urinary albumin (P = 0.008) were observed in pioglitazone-treated patients compared to untreated baseline levels. Arterial BP remained unchanged following pioglitazone treatment. T2DM patients had reduced HRV (low-frequency power; LF; P < 0.0001 and LF/HF; LF/HF; P < 0.0001) at baseline (clinostatism) compared to controls. Baseline clinostatic differences between groups persisted after pioglitazone treatment and no effect of treatment on basal HRV variables was observed. In controls, HF decreased and LF and LF/HF ratio increased in the orthostatic position. A similar effect for HF was observed in patients, but LF and LF/HF did not increase. The normal difference between HF-power in clinostatism versus orthostatism observed for controls (P < 0.0001) was restored in patients following pioglitazone treatment (P = 0.028). A significant decrease from lying to standing position in orthostatic LF-power (P < 0.0001) and LF/HF (P < 0.0001) was also observed between patients and controls. Although no differences in autonomic control of HRV were observed between controls and patients with T2DM, significant differences were observed in sympathovagal balance following either clinostatic or orthostatic challenge. These findings provide initial evidence of a potential additional benefit afforded by pioglitazone for the improvement of cardiac sympathovagal balance in T2DM.     

Decreased baroreflex sensitivity is linked to sympathovagal imbalance,low-grade inflammation,and oxidative stress in pregnancy-induced hypertension

Pregnancy-induced hypertension (PIH) has been reported as a cardiovascular (CV) risk. We assessed the sympathovagal imbalance (SVI) and the association of inflammation and oxidative stress (OS) with CV risks in PIH. A total of 125 pregnant women having a risk factor for PIH were followed till term and the incidence of PIH was observed. Retrospectively, they were divided into two groups: Group I (those who did not develop PIH, n = 82) and Group II (those who developed PIH, n = 43). Blood pressure variability (BPV) parameters including baroreflex sensitivity (BRS), spectral heart rate variability (HRV), autonomic function tests (AFTs), inflammatory markers (interleukin-6, TNF-α, interferon-γ), and OS markers were measured in both the groups. Alterations in parasympathetic and sympathetic components of AFTs were analyzed. Link of various parameters to BRS was assessed by correlation and multiple regression analysis. Parasympathetic components of AFTs were decreased from the early part of pregnancy and sympathetic components were increased toward the later part of pregnancy. Decreased BRS, the marker of CV risk, was more prominent in Group II subjects. Independent contribution of interleukin-6 (β = 0.276, P = 0.020), TNF-α (β = 0.408, P = 0.002), interferon-γ (β = 0.355, P = 0.008), and thiobarbituric-acid reactive substance (β = 0.287, P = 0.015) to BRS was found to be significant. It was concluded that sympathetic overactivity that develops more in the later part (third trimester) of pregnancy contributes to SVI and genesis of PIH. In PIH women, CV risks are present from the beginning of pregnancy that intensifies in the later part of pregnancy. Retrograde inflammation and oxidative stress contribute to the decreased BRS in PIH.     

Abnormal sympathovagal balance in men with fibromyalgia

OBJECTIVE: It is possible that there are differences in clinical manifestations between men and women with fibromyalgia syndrome (FM), especially in autonomic dysfunction; we assessed the interaction between the sympathetic and parasympathetic systems in postural change in men with FM using power spectral analysis (PSA) of heart rate variability (HRV), and investigated the pathogenesis of the orthostatic intolerance. METHODS: We studied 19 men with FM and 19 controls matched for age and sex. A high resolution electrocardiogram was obtained in supine and standing postures during complete rest. Spectral analysis of R-R intervals was done by the fast Fourier transform algorithm. RESULTS: PSA of HRV revealed that men with FM at rest are characterized by sympathetic hyperactivity and concomitantly reduced parasympathetic activity. During postural changes, male patients demonstrated an abnormal sympathovagal response. These results provide the physiological basis for the orthostatic intolerance in men with FM. CONCLUSION: This report of autonomic dysfunction in men with FM revealed an abnormal autonomic response to orthostatic stress. This abnormality may have implications regarding the symptoms of FM.     

Effect of complex amino acid imbalance on growth of tumor in tumor-bearing rats

AIM: To investigate the effect of complex amino acid imbalance on the growth of tumor in tumor-bearing (TB) rats.METHODS: Sprague-Dawlley (SD) rats underwent jejunostomy for nutritional support. A suspension of Walker256 carcinosarcoma cells was subcutaneously inoculated.TB rats were randomly divided into groups A, B, C and D according to the formula of amino acids in enteral nutritional solutions, respectively. TB rats received jejunal feedings supplemented with balanced amino acids (group A),methionine-depleted amino acids (group B), valine-depleted amino acids (group C) and methionine- and valine-depleted complex amino acid imbalance (group D) for 10 days. Tumor volume, inhibitory rates of tumor, cell cycle and life span of TB rats were investigated.RESULTS: The G0/G1 ratio of tumor cells in group D (80.5±9.0) % was higher than that in groups A, B and C which was 67.0±5.1 %, 78.9±8.5 %, 69.2±6.2 %, respectively (P＜0.05). The ratio of S/G2M and PI in group D were lower than those in groups A, B and C. The inhibitory rate of tumor in groups B, C and D was 37.2 %, 33.3 % and 43.9 %,respectively (P＜0.05). The life span of TB rats in group D was significantly longer than that in groups B, C, and A.CONCLUSION: Methionine/valine-depleted amino acid imbalance can inhibit tumor growth. Complex amino acids of methionine and valine depleted imbalance have stronger inhibitory effects on tumor growth.     

Visceral adiposity index (VAI), a powerful predictor of incident hypertension in prehypertensives

Prehypertension (defined by The Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, JNC-7) is relevant to a higher cardiovascular risk than normotensives. Early intervention in this particular population is essential to avoid progression into hypertension (HTN). This study is to explore whether visceral adiposity index (VAI) can strongly predict the incidence of HTN in community-based prehypertensives. A prospective observational cohort study was conducted from September 2011 to June 2012 in urban communities of Chengdu, Sichuan Province, China. 780 subjects (male 320, female 460) were evaluated on anthropometrical indices, blood pressure, blood samples, brachial-ankle pulse wave velocity, of whom 360 prehypertensives (male 160, female 200) were recruited for a 5-year follow-up. Overall, 97 subjects (male 37, female 60) developed HTN. The risk for developing HTN in the future increases with increasing VAI levels. The OR of the upper quartile is 3.719 (95% CI 1.481–9.338, P?=?0.005) after adjusting for confounders. The ROC results reveal that VAI is not considered superior to other indices on account of the significant overlapping confidence intervals. The area under the curves (AUC) of Model 5 (combination of VAI and WC) is significantly higher than BMI, WC and WHR (P?<?0.05). The AUC of Model 4 (combination of VAI and BMI) is found to be significantly higher than BMI and WHR (P?<?0.05), and is also higher than WC in all subject groups and in the male subgroup, but not in the female subgroup. VAI at baseline is an independent risk factor and early predictor of incident HTN in prehypertensives. The predictive value is not stronger than other traditional obesity indices (BMI, WC and WHR); however, it is superior to the latter by combining VAI and WC. Namely, VAI may help identify individuals at high risk of evolving into HTN in this particular population.     

血压正常高值者亚临床靶器官损害与危险因素相关性研究

目的探讨血压正常高值者亚临床靶器官损害与危险因素之间的相关性。方法将1 947例血压正常高值者按合并危险因素的数量分为0个危险因素组(482例)、1个危险因素组(499例)、2个危险因素组(493例)、≥3个危险因素组(473例)。所有受试者均进行危险因素调查,并进行颈动脉内膜中层厚度(IMT)、左心室重量指数(LVMI)以及尿微量白蛋白(microalbuminuria,MAU)检测。结果随着合并危险因素的增加,4组受试者的腰臀比、TC、TG、LDL-C、空腹血糖、吸烟史及家族史明显增高,HDL-C明显降低;IMT、LVMI、MAU明显增高(P<0.01);颈动脉粥样硬化、左心室肥厚、MAU异常率逐渐增加(P<0.01)。以0个危险因素组为基数,随着合并危险因素的增加,发生亚临床靶器官损害的风险比明显增加。结论随着合并危险因素数量的增加,血压正常高值者亚临床靶器官损害的危险性明显增加,危险因素之间具有联合协同作用。