Sympathovagal Imbalance in Prehypertensive Offspring of Two Parents versus One Parent Hypertensive

Whole-Body Vibration as Antihypertensive Non-Pharmacological Treatment in Hypertensive Individuals with Knee Osteoarthritis: Randomized Cross-Over Trial

(1) Background: Hypertension is a serious medical condition characterized by a persistent increase in blood pressure (BP), which is prevalent in individuals with knee osteoarthritis (KOA). Pharmacological interventions are normally used to treat both hypertension and KOA; however, a more sustainable form of treatment is desirable for these clinical conditions. Whole-body vibration (WBV) exercise has been proposed as a non-pharmacological therapy for reducing both BP and KOA symptomatology. This study aimed to evaluate the antihypertensive effect of WBV in hypertensive individuals with KOA. (2) Methods: Nineteen hypertensive individuals with KOA were randomly allocated to either a control (CG) (n = 9) or a WBV group (WBVG) (n = 10). Subjects in the WBVG were positioned sitting in a chair in front of a vibrating platform (VP) with the feet on the base (peak-to-peak displacement 2.5, 5.0 and 7.5 mm; frequencies 5 to 14 Hz). In the CG, subjects assumed the same position with the VP turned off. The protocols in the CG and WBVG were performed 2 days/week for a total of 5 weeks. (3) Results: No baseline differences (age, anthropometrics, BP parameters and medications) between the groups were found (p > 0.05). WBV exercise reduced systolic BP (SBP: 126.1 ± 2.7 versus 119.1 ± 3.2 mmHg; p = 0.001; post hoc: p = 0.02; F = 23.97) and mean BP (MBP: 82.6 ± 1.8 versus 78.7 ± 1.8, p = 0.001, post hoc: p = 0.02; F = 23.97), while no significant changes were found in diastolic BP (DBP: 68.5 ± 2.2 versus 64.4 ± 2.3; p = 0.11; F = 2.68). (4) Conclusions: WBV might be considered a sustainable therapy for exerting an antihypertensive effect in medicated hypertensive individuals with KOA. This decline in BP might translate to a reduction in pharmacological need, although further studies are necessary to understand the mechanisms underlying the described effect.

Neurocardiac regulation: from cardiac mechanisms to novel therapeutic approaches

Cardiac sympathetic overactivity is a well-established contributor to the progression of neurogenic hypertension and heart failure, yet the underlying pathophysiology remains unclear. Recent studies have highlighted the importance of acutely regulated cyclic nucleotides and their effectors in the control of intracellular calcium and exocytosis. Emerging evidence now suggests that a significant component of sympathetic overactivity and enhanced transmission may arise from impaired cyclic nucleotide signalling, resulting from compromised phosphodiesterase activity, as well as alterations in receptor-coupled G-protein activation. In this review, we address some of the key cellular and molecular pathways that contribute to sympathetic overactivity in hypertension and discuss their potential for therapeutic targeting.

Arterial Compliance and Autonomic Functions in Adult Male Smokers

INTRODUCTION

Smoking is known to augment sympathetic activity and may lead to increased arterial stiffness. Several studies have reported association of increased sympathetic activity and arterial stiffness to cardiovascular risks among smokers. Pulse Wave Velocity (PWV) of peripheral arteries, instead of aorta can be used as a non-invasive indicator of arterial stiffness.

AIM

To measure non-invasively, the autonomic functions and peripheral arterial stiffness in smokers, and to find out whether the aforementioned factors are modified by the level of physical activity in these smokers.

MATERIALS AND METHODS

This cross-sectional analytical study was conducted in the Department of Physiology, HIMS, Dehradun, over a period of 12 months (2013-2014) on 100 adult males (20-40 years); 50 smokers and 50 non-smokers. The parameters analysed include relevant anthropometric and cardiovascular parameters, Pulse Wave Velocity (PWV), sustained Hand Grip Test (HGT) and Heart Rate Variability (HRV) domains. Data interpretation and analysis was carried out using SPSS 17.0. Comparison of the above mentioned parameters amongst groups was done with unpaired t-test. The relationship of pack-years & physical activity with vascular functions was assessed by Pearson's correlation. Interaction of various grades of smoking and physical activity with Cardiovascular System (CVS) parameters was assessed by one-way ANOVA.

RESULTS

Smokers had higher values of PWV (5.7±0.5m/s) as compared to non-smokers (4.8±0.4m/s) (p<0.001). ΔDBP during HGT was lower (7±3.18mmHg) among smokers as compared to non-smokers (19.4±3.5mmHg) (p<0.001). Smoking (pack-years) was positively related to PWV (r= .03) but showed a weak negative relationship with change in Diastolic Blood Pressure (ΔDBP) (r= -0.084, p=0.56) showing that, more the frequency of smoking, the more was arterial stiffening and the lesser was the sympathetic response to the HGT. The smokers had significantly higher sympathetic activity; Low Frequency (LF) & Low Frequency: High Frequency ratio (LF: HF) (p<.001) whereas High Frequency (HF) was significantly lower (p<.001) showing a decline in parasympathetic activity.

CONCLUSION

Smokers demonstrated higher peripheral PWV and higher intrinsic sympathetic activity and this increase in intrinsic sympathetic activity may lead to increased arterial stiffness. Interaction of autonomic function and PWV with levels of physical activity and grades of smoking showed no significant differences, suggesting the fact that increased physical activity or reduced smoking may not have any effect on the endothelial dysfunction or CVS morbidity caused by smoking.

The role of maternal cardiac vagal control in the association between depressive symptoms and gestational hypertension

Reduced cardiac vagal control, indexed by relatively lower high-frequency heart rate variability (HF-HRV), is implicated in depressed mood and hypertensive disorders among non-pregnant adults whereas research in pregnancy is limited. This study examined whether maternal HF-HRV during pregnancy mediates the association between depressed mood and gestational hypertension. Depressive symptoms (Edinburgh Depression Scale) and HF-HRV were measured during early (M=14.9 weeks) and late (M=32.4 weeks) pregnancy in 287 women. Gestational hypertension was determined by chart review. Depressive symptoms were associated with less HF-HRV (b=-0.02, p=.001). There was an indirect effect of depressed mood on gestational hypertension through late pregnancy HF-HRV (b=0.04, 95% CI 0.0038, 0.1028) after accounting for heart rate. These findings suggest cardiac vagal control is a possible pathway through which prenatal depressed mood is associated with gestational hypertension, though causal ordering remains uncertain.

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.

The isometric handgrip exercise as a test for unmasking hypertension in the offsprings of hypertensive parents

BACKGROUND

A familial history of hypertension increases the risk of hypertension in the offsprings.

AIMS AND OBJECTIVES

The present study was undertaken to assess the underlying hypertension by using the Isometric Handgrip (IHG) exercise test in the offsprings of hypertensive parents and to compare it with age-matched controls of normotensive parents.

MATERIAL AND METHODS

The isometric handgrip test was performed in the study and control groups. The resting blood pressure was recorded before exercise and afterwards the subjects were asked to perform the isometric handgrip exercise with the dominant hand for 2 minutes. Then the blood pressure was recorded in the sitting position during and 5 minutes after the completion of the exercise.

STATISTICAL ANALYSIS

The analysis of the results was done by ANOVA with SPSS, version 17.0, by using the unpaired 't' test.

RESULTS

The results showed that the Resting Systolic (SBP), Diastolic (DBP) and the Mean (MBP) Blood Pressures were higher (p <0.001) in the offsprings of the hypertensive parents as compared to those in the control subjects of normotensive parents. During the isometric handgrip exercise test, the rise in the systolic, diastolic and the mean blood pressures was significantly higher (p<0.001) in the offsprings of the hypertensive parents. After 5 minutes of exercise, the SBP, DBP and the MBP were found to be significantly higher (p<0.001) in the study group as compared to those in the control group.

CONCLUSIONS

An early and a regular screening of the children of hypertensive parents is necessary to prevent any future cardiovascular complications.

Cardiovascular autonomic response to amlodipine in primary hypertension

Sympathetic hyperactivity may be involved in primary hypertension. The purpose of this study was to evaluate both sympathetic and vagal activity responses in patients receiving amlodipine as antihypertensive agent. Patients and Methods. This prospective study included a group of primary hypertensive patients (N = 32, mean age 54.6 ± 7.6 years). The cardiovascular autonomic tests performed in this group, before and after 3 months of daily oral administration of amlodipine, included deep breathing, hand-grip, and mental stress tests. Statistical analysis was done using the Student's t-test. Results. Cardiovascular autonomic reflexes responses before and after 3 months of amlodipine oral administration were as follows: the mental stress test stimulation method produced a central alpha adrenergic response of 23.9 ± 8.7% versus 11.2 ± 2.0% (P < 0.05), a central beta sympathetic response of 16.7 ± 9.2% versus 10.4 ± 1.3% (P < 0.05), a blood pressure increase in response to hand grip test of 20.5 ± 7.3% versus 10.7 ± 2.4% (P < 0.05), vagal response to deep breathing test was 21.2 ± 6.5% versus 30.8 ± 2.9%, (P < 0.05). Conclusion. The results attest that amlodipine may have an anti-sympathetic effect.

Body mass index contributes to sympathovagal imbalance in prehypertensives

BACKGROUND

The present study was conducted to assess the nature of sympathovagal imbalance (SVI) in prehypertensives by short-term analysis of heart rate variability (HRV) to understand the alteration in autonomic modulation and the contribution of BMI to SVI in the genesis of prehypertension.

METHODS

Body mass index (BMI), basal heart rate (BHR), blood pressure (BP), rate pressure product (RPP) and HRV indices such as total power (TP), low-frequency power (LF), normalized LF (LFnu), high-frequency power (HF), normalized HF (HFnu), LF-HF ratio, mean heart rate (mean RR), square root of the mean squared differences of successive normal to normal intervals (RMSSD), standard deviation of normal to normal RR interval (SDNN), 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 having normal BMI (Group 1), prehypertensives having normal BMI (Group 2) and prehypertensives having higher BMI (Group 3). SVI was assessed from LF-HF ratio and correlated with BMI, BHR, BP and RPP in all the groups by Pearson correlation. The contribution of BMI to SVI was assessed by multiple regression analysis.

RESULTS

LF and LFnu were significantly increased and HF and HFnu were significantly decreased in prehypertensive subjects in comparison to normotensive subjects and the magnitude of these changes was more prominent in subjects with higher BMI compared to that of normal BMI. LF-HF ratio, the sensitive indicator of sympathovagal balance had significant correlation with BMI (P=0.000) and diastolic blood pressure (DBP) (P=0.002) in prehypertensives. BMI was found to be an independent contributing factor to SVI (P=0.001) in prehypertensives.

CONCLUSIONS

It was concluded that autonomic imbalance in prehypertensives manifested in the form of increased sympathetic activity and vagal inhibition. In prehypertensives with higher BMI, vagal withdrawal was predominant than sympathetic overactivity. Magnitude of SVI (alteration in LF-HF ratio) was linked to changes in BMI and DBP. BMI had an independent influence on LF-HF ratio. It was advised that life-style modifications such as yoga and exercise would enable achieve the sympathovagal balance and blood pressure homeostasis in prehypertensives.