Pathophysiology of essential hypertension: an update.

INTRODUCTION: Hypertension is caused by increased cardiac output and/or increased peripheral resistance. Areas covered: The various mechanisms affecting cardiac output/peripheral resistance involved in the development of essential hypertension are covered. These include genetics; sympathetic nervous system overactivity; renal mechanisms: excess sodium intake and pressure natriuresis; vascular mechanisms: endothelial cell dysfunction and the nitric oxide pathway; hormonal mechanisms: the renin-angiotensin-aldosterone system (RAAS); obesity, obstructive sleep apnea (OSA); insulin resistance and metabolic syndrome; uric acid; vitamin D; gender differences; racial, ethnic, and environmental factors; increased left ventricular ejection force and hypertension and its association with increased basal sympathetic activity - cortical connections. Expert commentary: Maximum association of hypertension is found with sympathetic overactivity which is directly or indirectly involved in different mechanisms of hypertension including RAAS, OSA, obesity, etc.. It is not overt sympathetic activity but disturbed basal sympathetic tone. Basal sympathetic tone arises from hypothalamus; possibly affected by cortical influences. Therefore, hypertension is not merely a disease of circulatory system alone. Its pathogenesis involves alteration in ANS (autonomic nervous system) and likely in cortical-hypothalamic connections. Assessment of ANS and cortical-hypothalamic connections may be required for better understanding of hypertension.

Assessment of left ventricular ejection force and sympathetic skin response in normotensive and hypertensive subjects: A double-blind observational comparative case-control study.

BACKGROUND: Pathophysiology of essential hypertension remains obscure. Correlation among ventricular ejection force, sympathetic activity, and hypertension is less clearly narrated in hypertensive subjects. AIMS AND OBJECTIVES: To assess correlation among ventricular ejection force, sympathetic activity, and hypertension in hypertensive subjects, and to be compared with normotensive subjects. METHODS: This is a case-control study to assess left ventricular ejection force (LVEF) and sympathetic skin response, in normotensive (group 1; control), and hypertensive subjects (group 2; cases). 100 cases were selected. Subjects having stages 1 and 2 hypertension were categorized in groups 2A and 2B, respectively. LVEF was calculated by using echocardiography observing aortic acceleration time (AT) and peak systolic velocity. Comparison among groups was done by using one-way ANOVA. RESULTS: Both groups were comparable. In group 2, 60 cases had stage 1 hypertension and 40 had stage 2 hypertension. Significantly short AT and significantly high LVEF were found in hypertension (groups 2A and 2B) (p<0.0001). Sympathetic activity was high in group 2A (p<0.0001). Stroke volume (SV) was high in group 2B (p<0.0001). CONCLUSION: Stage 1 hypertension is a stage of increased sympathetic activity, leading to increased LVEF and hypertension (resetting of baroreceptors); stage 2 hypertension is a stage of normal sympathetic activity, increased LVEF, increased SV, and hypertension (possibly a stage of shift of renal equilibrium curve/renal output curve and blood pressure to a newer level).

Aetiopathogenesis of type-2 diabetes mellitus: could chronic stress play an important role?

OBJECTIVES: Pathogenesis of type-2 diabetes remains elusive. Various factors including diet, physical exercise, obesity, genetic factors and stress, have been discussed. Among these factors role of stress is still poorly understood in diabetes. Therefore the study was planned to assess effect of stress in diabetic and non-diabetic population in a comparative descriptive manner. METHODS: 1000 diabetic cases (group A) and equal number of healthy individuals were selected as a comparison group (group B). Both groups were examined at 0, 12, 24 months. To assess stress 17 points were examined (factors mainly related to emotions, hurriedness, relaxed status etc.), total 68 points for stress were given; > 30/68 was considered as severe stress. Mental health life style factors like duration of sleep and working mental hours were also examined. EEG and SSR were done at 24 months to assess stress and sympathetic response. RESULTS: There was presence of chronic stress, (> 90% had > 30/68 scoring) more mental work and less sleep duration in group A. EEG showed synchronised v/s desynchronised basal rhythm in group B v/s group A. SSR suggestive of increased sympathetic activity in group A. CONCLUSION: It is concluded that chronic stress leads to increased basal sympathetic activity, resulting from disturbed cortical hypothalamic axis, leading to central insulin resistance and diabetes.

The effect of various breathing exercises (pranayama) in patients with bronchial asthma of mild to moderate severity.

BACKGROUND/AIM: The incidence of bronchial asthma is on increase. Chemotherapy is helpful during early course of the disease, but later on morbidity and mortality increases. The efficacy of yoga therapy though appreciated is yet to be defined and modified. AIM: To study the effect of breathing exercises (pranayama) in patients with bronchial asthma of mild to moderate severity. MATERIALS AND METHODS: Fifty cases of bronchial asthma (Forced Expiratory Volume in one second (FEV1) > 70%) were studied for 12 weeks. Patients were allocated to two groups: group A and group B (control group). Patients in group A were treated with breathing exercises (deep breathing,Brahmari, and Omkara, etc.) for 20 minutes twice daily for a period of 12 weeks. Patients were trained to perform Omkara at high pitch (forceful) with prolonged exhalation as compared to normal Omkara. Group B was treated with meditation for 20 minutes twice daily for a period of 12 weeks. Subjective assessment, FEV1%, and Peak Expiratory Flow Rate (PEFR) were done in each case initially and after 12 weeks. RESULTS: After 12 weeks, group A subjects had significant improvement in symptoms, FEV1, and PEFR as compared to group B subjects. CONCLUSION: Breathing exercises (pranayama), mainly expiratory exercises, improved lung function subjectively and objectively and should be regular part of therapy.