Sympathetic Cardiovascular Function Research Articles

Preferential impairment of parasympathetic autonomic function in type 2 diabetes.

Cardiovascular autonomic neuropathy is a known complication in type 2 diabetes (T2D). However, the extent of sympathetic dysfunction and its relation to blood pressure (BP) dysregulation is insufficiently studied. We therefore assessed the cardiovascular sympathetic function using a standardized autonomic test-battery. Forty T2D patients (mean age and duration of diabetes ±SD, 65.5±7.3 and 9.5±4.2years) and 40 age- and gender-matched controls were examined through autonomic testing, assessing cardiovascular responses to deep breathing, Valsalva maneuver and tilt-table testing. Additionally, 24-hour oscillometric BP and self-reported autonomic symptoms on COMPASS-31 questionnaire was recorded. Patients with T2D had reduced parasympathetic activity with reduced deep breathing inspiratory:expiratory-ratio (median [IQR] T2D 1.11 [1.08-1.18] vs. controls 1.18 [1.11-1.25] (p=0.01)), and reduced heart rate variability (p<0.05). We found no differences in cardiovascular sympathetic function measured through BP responses during the Valsalva maneuver (p>0.05). 24-hour-BP detected reduced night-time systolic BP drop in T2D (9.8%±8.8 vs. controls 15.8%±7.7 (p<0.01)) with more patients having reverse dipping. Patients with T2D reported more symptoms of orthostatic intolerance on the COMPASS-31 (p=0.04). Patients with T2D showed reduced parasympathetic activity but preserved short-term cardiovascular sympathetic function, compared to controls, indicating autonomic dysfunction with predominantly parasympathetic impairment. Despite this, T2D patients reported more symptoms of orthostatic intolerance in COMPASS-31 and had reduced nocturnal BP dipping, indicating that these are not a consequence of cardiovascular sympathetic dysfunction.

Relationship between Obesity and Sympathetic Nerve Function Status

In order to assess the effect of obesity on sympathetic nervous system a cross-sectional observational study was carried out in the Department of Physiology, Sylhet MAG Osmani Medical College between January 2017 and December 2017. Fifty obese and age-sex matched 50 non-obese subjects were included. Two non-invasive cardiovascular sympathetic function tests like blood pressure response to postural change (orthostatic test) and blood pressure response to sustained handgrip were done to assess sympathetic nerve function status.The fall in systolic blood pressure (SBP) in orthostatic test of obese group (9.02 ± 2.29 mmHg) was significantly higher compared to non-obese group (4.84 ± 0.96) (p&lt;0.001). Increase in diastolic blood pressure (DBP) in handgrip test of obese group (12.36 ± 2.78 mmHg) was significantly lesser than that of non-obese group (20.12 ± 2.64 mmHg) (p&lt;0.001). The results of this study suggested that obese adults have reduced sympathetic activity.

Assessment of cardiovascular sympathetic function tests in premenstrual syndrome patients visiting tertiary care hospital: A case–control study

Background: Premenstrual syndrome (PMS) is a stress-induced disorder and is showing a rising prevalence but its etiopathogenesis is not yet understood. Stress disturbs the balance of the sympathetic and parasympathetic nervous system. Alteration in heart rate and blood pressure is the most important physiological response following stress-induced sympathetic changes. Aims and Objectives: The present study was designed to test the hypothesis of an association between sympathetic functions and PMS and to observe the degree of changes (if any) in these sympathetic functions. The study also aims to provide timely interventions to prevent the development of cardiovascular complications and improve lifestyle. Materials and Methods: A Menstrual Distress Questionnaire was used to evaluate physical, emotional, and behavioral symptoms accompanying the menstrual cycle of the subjects who fulfilled the inclusion criteria. Based on the scores obtained by their questionnaire, subjects with the higher scores formed the PMS group, while the age-matched females with low score served as controls. Cardiovascular sympathetic functions were assessed by standardized, simple, non-invasive tests which included Handgrip test and orthostatic hypotension test. Unpaired Student’s t-test was used for statistical analysis. Results: The results revealed that the sympathetic reactivity is insignificantly higher in PMS group during the follicular phase. During the luteal phase, sympathetic activity is significantly increased. Conclusion: PMS involves psychoneuroendocrinal turmoil, thus early screening of high-risk groups and interventions such as relaxation techniques and lifestyle modification can prevent further cardiovascular complications in patients of high sympathetic responses.

The Effect of High Temperature on Cardiovascular Autonomic Function Tests in Steel Plant Furnace Worker

Background:The high temperature in the working environment could be one of the risk factors for cardiovascular diseases in steel plant workers. The excessive high temperature at the working place leads to altered autonomic activity and is related to more cardiovascular risk.Aims and Objectives:The effect of high temperature on cardiovascular autonomic function tests in steel plant furnace worker.Material and Method:This was a case-control study for which 50 steel plant furnace workers and 50 controls were selected. The cardiovascular sympathetic function status in worker and control were analyzed by three tests: (i) Blood pressure (BP) response to sustained isometric handgrip test, (ii) BP response to the cold pressor test, and (iii) BP response to standing from a supine position (orthostasis). Statistical analysis was done by using an independent t-test.Results:Diastolic BP (DBP) response to sustained isometric handgrip and systolic BP (SBP) and DBP response to the cold pressor test showed that the increase BP in workers were more than controls but the difference was not statistically significant (P > 0.05). SBP response to standing from the supine position showed statistically significant (P < 0.001) greater fall in steel plant workers.Conclusion:The sympathetic autonomic dysfunction was seen in steel furnace workers in response to environmental stressor–excessive heat.

Differences in correlations of depression and anhedonia with cardiovascular sympathetic functions during a head-up tilt test in drug-naïve Parkinson's disease patients.

Depression is a symptom of Parkinson's disease (PD) and may be correlated with cardiovascular sympathetic function. Anhedonia is an element of depression, but these symptoms can emerge independently in PD. A correlation of anhedonia with cardiovascular sympathetic function has rarely been examined. To compare correlations of depression and anhedonia with cardiovascular sympathetic function in drug-naive PD patients. Assessments of depression (Self-rating Depression Scale; SDS), anhedonia (Snaith-Hamilton Pleasure Scale; SHAPS), myocardial 123I-MIBG (123I-meta-iodobenzylguanidine) scintigraphy (heart to mediastinum (H/M) ratios in early and delayed images), and head-up tilt test (HUT) up to 60° for 10min were performed in 45 drug-naïve PD patients. During the HUT, blood pressure was measured every minute and the maximum decrease in systolic blood pressure (SBP) was determined. Plasma noradrenaline (NA) and arginine vasopressin (AVP) levels were examined at baseline and 10min after tilt, with subsequent calculation of increases in plasma NA and AVP levels in this 10min. Correlation coefficients were calculated among these assessment parameters. SDS significantly correlated with % maximum decrease in SBP (r = 0.344, p = 0.02), but not with H/M ratios in both images and increases in plasma NA and AVP levels. SHAPS did not correlate with the change in SBP, H/M ratios in both images, or plasma NA and AVP levels. Depression was correlated with the % maximum decrease in SBP during a 10-min HUT, but anhedonia did not show this relationship. This suggests that depression and anhedonia may have different pathophysiological backgrounds in drug-naïve PD patients.

Sympathetic cardiovascular function status of chronic obstructive pulmonary disease (COPD)

Background: Chronic obstructive pulmonary disease (COPD) is a chronic progressive obstructive airway disease which is often associated with cardiovascular diseases. Sympathetic dysfunction may complicate the cardiovascular diseases which may in turn increase the morbidity and mortality in COPD patients.&#x0D; Objective: Aim of this study was to evaluate sympathetic cardiovascular function status of COPD patients to reduce the cardiovascular complication in those patients.&#x0D; Methods: This comparative cross-sectional study was carried out at the department of Physiology and department of Medicine, Rajshahi Medical College, Rajshahi from July 2013 to June 2014.&#x0D; Results: A total number of 80 subjects aged 40-55 years were selected, among which 40 were clinically diagnosed COPD patients (case) and 40 were age, sex and BMI matched apparently healthy persons for comparison (control group). To observe sympathetic cardiovascular function status resting pulse rate, resting systolic BP, resting diastolic BP, decline of systolic BP in response to standing from lying position (orthostatic test) and rise of diastolic BP in response to sustained hand grip for 5 minutes (isometric exercise test) were measured. For statistical analysis Independent sample t-test, and Pearson’s correlation coefficient test were performed. In this study resting pulse rate, systolic BP, diastolic BP and rise of diastolic blood pressure in isometric exercise test were significantly increased in COPD than in healthy control group. On the other hand, decline of systolic blood pressure in orthostatic test was significantly decreased in COPD than in control group.&#x0D; Conclusion: This study concludes that sympathetic cardiovascular function is overactive in COPD and sympathetic over activity correlates with severity of the disease.

The Investigation of the Cardiovascular and Sudomotor Autonomic Nervous System-A Review.

The autonomic nervous system as operating system of the human organism permeats all organ systems with its pathways permeating that it is involved with virtually all diseases. Anatomically a central part, an afferent part and sympathetic and parasympathetic efferent system can be distinguished. Among the different functional subsystems of the autonomic nervous system, the cardiovascular autonomic nervous system is most frequently examined with easily recordable cardiovascular biosignals as heart rate and blood pressure. Although less widely established, sudomotor tests pose a useful supplement to cardiovascular autonomic assessment as impaired neurogenic sweating belongs to the earliest clinical signs of various autonomic neuropathies as well as neurodegenerative disorders and significantly reduces quality of life. Clinically at first, the autonomic nervous system is assessed with a detailed history of clinical autonomic function and a general clinical examination. As a lof of confounding factors can influence autonomic testing, subjects should be adequately prepared in a standardized way. Autonomic testing is usually performed in that way that the response of the autonomic nervous system to a well-defined challenge is recorded. As no single cardiovascular autonomic test is sufficiently reliable, it is recommended to use a combination of different approaches, an autonomic test battery including test to measure parasympathetic and sympathetic cardiovascular function (deep breathing test, Valsalva maneuver, tilt, or pressor test). More specialized tests include carotid sinus massage, assessment of baroreceptor reflex function, pharmacological tests or cardiac, and regional hemodynamic measurements. Techniques to measure functional integrity of sudomotor nerves include the quantitative sudomotor axon reflex sweat test, analysis of the sympathetic skin response as well as the thermoregulatory sweat test. In addition to these rather established techniques more recent developments have been introduced to reduce technical demands and interindividual variability such as the quantitative direct and indirect axon reflex testing or sudoscan. However, diagnostic accuracy of these tests remains to be determined. We reviewed the current literature on currently available autonomic cardiovascular and sudomotor tests with a focus on their physiological and technical mechanisms as well as their diagnostic value in the scientific and clinical setting.

Influence of menopause on cardiovascular responses to behavioral stressors: A comparative study

Background: There is increased cardiovascular morbidity and mortality in post-menopausal women as compared to pre‑menopausal women. There is an altered autonomic control with a shift toward sympathetic hyperactivity in menopause. Abnormal autonomic activity, behavioral stressors, and estrogen deficiency are related with increased cardiovascular risk. However, the underlying cardiovascular mechanisms in menopause still remain unclear. Aims and Objectives: The aim of this study is to determine and compare the following parameters indicating cardiovascular sympathetic function status in pre-menopausal and post-menopausal women subjected to three behavioral stress tests: (i) Blood pressure (BP) response to sustained isometric handgrip test, (ii) BP response to cold pressor test, and (iii) BP response to standing from supine position (orthostasis). Materials and Methods: This was a cross-sectional study for which 150 pre-menopausal and 150 post-menopausal women were selected. They underwent three behavioral stress tests of sustained isometric handgrip test, cold pressor test, and orthostatic test. The parameters indicating cardiovascular sympathetic function status were determined. Statistical analysis was performed using Z-test. Results: Diastolic BP (DBP) response to sustained isometric handgrip and systolic BP (SBP) and DBP response to the cold pressor test showed statistically highly significant (P 0.05) greater fall in post-menopausal women. Conclusion: Sympathetic hyperactivity in response to behavioral stressors seen in post-menopausal women as compared to pre-menopausal women, suggests that the cardiovascular changes related to estrogen deficiency occurring in menopause may trigger adverse cardiovascular events.

Aerobic Exercise and Strength Training Effects on Cardiovascular Sympathetic Function in Healthy Adults

Exercise has widely documented cardioprotective effects, but the mechanisms underlying these effects are not entirely known. Previously, we demonstrated that aerobic but not strength training lowered resting heart rate and increased cardiac vagal regulation, changes that were reversed by sedentary deconditioning. Here, we focus on the sympathetic nervous system and test whether aerobic training lowers levels of cardiovascular sympathetic activity in rest and that deconditioning would reverse this effect. We conducted a randomized controlled trial contrasting the effects of aerobic (A) versus strength (S) training on indices of cardiac (preejection period, or PEP) and vascular (low-frequency blood pressure variability, or LF BPV) sympathetic regulation in 149 young, healthy, and sedentary adults. Participants were studied before and after conditioning, as well as after 4 weeks of sedentary deconditioning. As previously reported, aerobic capacity increased in response to conditioning and decreased after deconditioning in the aerobic, but not the strength, training group. Contrary to prediction, there was no differential effect of training on either PEP (A: mean [SD] -0.83 [7.8] milliseconds versus S: 1.47 [6.69] milliseconds) or LF BPV (A: mean [SD] -0.09 [0.93] ln mm Hg(2) versus S: 0.06 [0.79] ln mm Hg(2)) (both p values > .05). These findings, from a large randomized controlled trial using an intent-to-treat design, show that moderate aerobic exercise training has no effect on resting state cardiovascular indices of PEP and LF BPV. These results indicate that in healthy, young adults, the cardioprotective effects of exercise training are unlikely to be mediated by changes in resting sympathetic activity. Clinicaltrials.gov identifier: NCT00358137.

Comparative study of sympathetic cardiovascular parameters in overweight, normal and underweight school children in southern Odisha basing on BMI criteria

This study was undertaken to investigate and compare the sympathetic cardio vascular parameters in age matched overweight, underweight and normal weight school going boys in southern Odisha. 75 Boys between age group of 12-16 were subjected to study out of which 25 were overweight (BMI>25), next 25 were underweight(BMI<18.5),rest 25 were control group having normal BMI. Cold pressure test and hand grip dynamometer test were performed and blood pressure was measured during and after the tests as measures of cardiovascular parameter. Baseline SBP and MAP were significantly higher in overweight boys & lower in underweight boys. Maximum rise of SBP, DBP & MAP during hand grip dynamometer test were significantly higher in overweight boys & lower in underweight boys. Increase in SBP & MAP from their basal value during cold pressure test were significantly lower in overweight boys & higher in underweight boys. Thus it is concluded that both overweight & underweight boys have derangement of sympathetic cardiovascular function. SBP- Systolic blood pressure, DBP- Diastolic blood pressure , MAP- Mean arterial pressure

Cardiac Iodine-123 Metaiodobenzylguanidine (123I-MIBG) Scintigraphy Parameter Predicts Cardiac and Cerebrovascular Events in Type 2 Diabetic Patients Without Structural Heart Disease

Cardiac iodine-123 metaiodobenzylguanidine ((123)I-MIBG) scintigraphy is an established method of assessment of cardiovascular sympathetic function. The aim of the present study was to investigate the long-term cardiovascular predictive value of cardiac (123)I-MIBG scintigraphy parameters in Japanese type 2 diabetic patients without structural heart disease. Cardiac (123)I-MIBG scintigraphy in 108 patients with type 2 diabetes who did not have structural heart disease, was evaluated. The washout rate (WR) was considered enhanced if it was ≥40%. Accurate follow-up information for 4.6 years was obtained in 54 enhanced WR patients (27 male; mean age, 61 ± 11 years) and in 54 sex- and age-matched preserved WR patients (27 male; mean age, 61 ± 10 years). Major adverse cardiac and cerebrovascular events (MACCE) were investigated. During follow-up, 10 enhanced WR patients developed MACCE including cardiac death, coronary revascularization, stroke, and congestive heart failure, while MACCE occurred in only 3 male patients. The Kaplan-Meier curves indicated that enhanced WR patients had higher incidence of MACCE than those with preserved WR (P<0.05). Cox proportional hazards regression analysis showed that age and enhanced WR were independently associated with the incidence of MACCE (hazard ratio, 4.06; 95% confidence interval: 1.194-18.76, P = 0.0237). Abnormal WR of cardiac (123)I-MIBG scintigraphy at baseline has long-term cardiovascular predictive value in Japanese patients with type 2 diabetes without structural heart disease.

Cardiovascular and Sympathetic Effects of Disrupting Tyrosine 985 of the Leptin Receptor

Leptin acts in the brain to regulate food intake and energy expenditure. Leptin also increases renal sympathetic nerve activity and arterial pressure. The divergent signaling capacities of the leptin receptor (ObRb) mediate the stimulation of various intracellular pathways that are important for leptin control of physiological processes. We evaluated the cardiovascular and sympathetic consequences of disrupting the signal emanating from tyrosine985 of ObRb. For this, we used Lepr(L985) (l/l) mice, which carry a loss of function mutation replacing tyrosine985 of ObRb with leucine. Body weight of l/l mice was not significantly different from wild-type controls. In contrast, radiotelemetry measurements revealed that the l/l mice had higher arterial pressure and heart rate as compared with controls. Ganglionic blockade caused a greater arterial pressure fall in the l/l mice relative to controls. In addition, leptin treatment induced a larger increase in arterial pressure and heart rate in the l/l versus wild-type mice. Finally, we compared the response of renal and brown adipose tissue sympathetic nerve activity to intracerebroventricular injection of leptin (2 μg) between l/l and control mice. Leptin-induced increase in renal sympathetic nerve activity was greater in l/l mice relative to controls. In contrast, the brown adipose tissue sympathetic nerve activity response to leptin was attenuated in the l/l mice relative to controls. These data indicate that selective loss of leptin receptor signaling emanating from tyrosine985 enhances the cardiovascular and renal sympathetic effects of leptin. These findings provide important insight into the molecular mechanisms underlying leptin's effects on the sympathetic cardiovascular function and arterial pressure.

Right cerebellar peduncle neurocysticercois presenting with bradycardia

Dear editor, Bradycardia in neurosurgical practice is usually attributable to raised intracranial tension. Rarely bradycardia may occur due to the direct involvement of the vasomotor center within the brainstem [5]. Brain stem lesions are known to cause cardiovascular autonomic dysfunction [3]. Neurocysticercosis a parasitic disease of central nervous system commonly presents with seizures, headache or focal neurological deficit. Bradycardia is known in neuricysticercosis with raised intracranial pressure. We present a case of neurocysticercosis of right cerebellar peduncle with bradycardia for 5 years and no evidence of increased intracranial pressure. Surgical excision of the cyst cured the bradycardia. A 32-year-old male, diagnosed as sick sinus syndrome since 5 years presented with headache, giddiness, and imbalance for the past 20 days. The patient's pulse was regular, normal volume and 50/min at rest. The examination of the patient was normal except for cerebellar signs. Fundus examination was normal. MRI of the brain showed a smooth walled cyst within the right middle cerebellar peduncle (Fig. 1) with no obvious solid portion. The cyst did not enhance on contrast administration. In view of the progressive cerebellar deficits and ambiguous nature of the cyst etiology, the cyst was excised. The patient had a rapid recovery from the headaches and cerebellar deficits. It was noted that the patient's bradycardia had resolved and the pulse rate was in the normal range. Histopathology confirmed neurocysticercosis. The patient was treated with a course of albendazole. The patient was symptom free with a normal pulse at follow-up at 3 months. A cardiac review of the patient was normal. Brainstem is an essential region in the regulation of the autonomic cardiovascular functions. Bradycardia is a classic sign of the Cushing's reflex denoting raised intracranial tension [1]. Central or uncal herniation due to intracranial pressure leads to compression and stretching of the brainstem, responsible for bradycardia. The vasomotor area in the medulla may be responsible for this. The importance of this region in parasympathetic and sympathetic cardiovascular functions is known. Manipulation of the medulla is known to cause bradycardia during surgery [2, 7]. Activation of sublobule IX-b of the cerebellar vermis has been shown to evoke hypotension, bradycardia, and decrease of phrenic nerve activity in anesthetized animal

Sympathetic Activation in Congestive Heart Failure: Evidence, Consequences and Therapeutic Implications

Congestive heart failure (CHF) is characterized not only by profound abnormalities in the haemodynamic profile but also by changes in sympathetic cardiovascular function. These neurogenic abnormalities are important features of the disease that can affect the prognosis of CHF and to become a target for therapeutic intervention. This article addresses 4 major issues. It will first examine the evidence that a hyperadrenergic state is a hallmark of CHF, based on data collected via indirect (plasma norepinephrine, power spectral analysis of the heart rate signal) and direct (microneurography, norepinephrine spillover, radioimaging techniques visualizing myocardial neural network) approaches. It will then provide an overview on the central, reflex and metabolic factors potentially responsible for the phenomenon. The review also analyses the clinical consequences of the adrenergic alteration, with particular emphasis on the effects of the sympathetic overdrive on disease progression, arrhythmogenic threshold, adverse clinical outcomes as well as sudden death. The final part of the review will examine the therapeutic implications of the above mentioned findings and discuss the effects of pharmacological and non- pharmacological interventions on the sympathetic abnormalities of the heart failure state.

Adrenergic Overdrive as the Link Among Hypertension, Obesity, and Impaired Thermogenesis

The sympathetic nervous system plays a pivotal role in both blood pressure and metabolic homeostatic control by regulating cardiac output, peripheral vascular resistance, heat production, and resting metabolic rate, which accounts for a large fraction of adult energy expenditure. Throughout the years, the attractive hypothesis based on this evidence has been advanced that an alteration in blood pressure regulation, as well as in thermogenesis control exerted by the sympathetic nervous system, represents the pathogenetic background for 2 diseases of common detection in current clinical practice, that is, hypertension and obesity, respectively. As far as high blood pressure is concerned, a number of studies based on indirect or direct methodologic approaches to assess neuroadrenergic function have unequivocally demonstrated that a hyperactivity of the sympathetic nervous system contributes at the development, maintenance, and progression of the hypertensive state.1–4 They have also shown that neurogenic mechanisms favor the genesis of hypertension-related end organ damage, that is, left ventricular hypertrophy, arterial and arteriolar hypertrophy, and vascular remodelling.5,6 Even when blood pressure is normal, an adrenergic overdrive has also been reported in the obese state,7,8 and independent but additive increases in sympathetic activity have been described when obesity is coupled with hypertension.9 Traditionally, obesity-related hypertension has been regarded, at least in part, as the result of a hyperactivity of the sympathetic nervous system, related to some extent to the weight-associated increase in sympathetic cardiovascular drive.9,10 …

COLD PRESSOR TEST DEMONSTRATES RESIDUAL SYMPATHETIC CARDIOVASCULAR ACTIVATION IN FAMILIAL DYSAUTONOMIA

In familial dysautonomia (1713), i.e. Riley‐Day‐syndrome, sympathetic cardiovascular function, as well as afferent temperature and pain mediating neurons, are significantly reduced. Thus, it was questioned if cold pressor test (CPT), which normally enhances sympathetic outflow and induces peripheral vasoconstriction by the activation of thermo‐ and nociceptive system activation, could be used to assess sympathetic function in FD. To evaluate whether CPT can be used to assess sympathetic activation in FD, we performed CPT in 15 FD patients and IS controls. After a 35‐min resting period, participants immersed their right hand and arm up to the elbow into 0‐1°C cold water while we monitored heart rate (HR), respiration, beat‐to‐beat radial artery blood pressure (BP), and laser Doppler skin blood flow (SBF) at the right index finger pulp. From these measurements, heart rate variability parameters were calculated: root mean square of successive differences (RMSSD), coefficient of variation (CV), low and high frequency (LF, HF) power spectra of the electrocardiogram (ECG). All participants perceived cold stimulation and indicated discomfort. In controls, SBF decreased and HR and BP increased rapidly upon CPT. After 60 s, SBF indicated secondary vasodilatation in six controls, BP rise attenuated and HR returned to baseline in all controls. In the patients, SBF remained unchanged, HR and BP increased significantly, but after 50‐60 s of CPT and changes were lower than in controls (p*LT0.05). RMSSD and CV decreased and LF increased significantly only in the controls. We conclude that CPT activates sympathetic HR and BP modulation despite impaired pain and temperature perception in FD patients. BP increase in the presence of almost unchanged SBF might be due to HR increase and to nociceptive arousal and emotionally induced catecholamine release as seen in emotional crises of FD patients. CPT assesses sympathetic cardiovascular responses independently from baroreflex function, which is compromised in FD.

Cold pressor test demonstrates residual sympathetic cardiovascular activation in familial dysautonomia

In familial dysautonomia (FD), i.e. Riley–Day-syndrome, sympathetic cardiovascular function, as well as afferent temperature and pain mediating neurons, are significantly reduced. Thus, it was questioned if cold pressor test (CPT), which normally enhances sympathetic outflow and induces peripheral vasoconstriction by the activation of thermo- and nociceptive system activation, could be used to assess sympathetic function in FD. To evaluate whether CPT can be used to assess sympathetic activation in FD, we performed CPT in 15 FD patients and 18 controls. After a 35-min resting period, participants immersed their right hand and arm up to the elbow into 0–1 °C cold water while we monitored heart rate (HR), respiration, beat-to-beat radial artery blood pressure (BP), and laser Doppler skin blood flow (SBF) at the right index finger pulp. From these measurements, heart rate variability parameters were calculated: root mean square of successive differences (RMSSD), coefficient of variation (CV), low and high frequency (LF, HF) power spectra of the electrocardiogram (ECG). All participants perceived cold stimulation and indicated discomfort. In controls, SBF decreased and HR and BP increased rapidly upon CPT. After 60 s, SBF indicated secondary vasodilatation in six controls, BP rise attenuated and HR returned to baseline in all controls. In the patients, SBF remained unchanged, HR and BP increased significantly, but after 50–60 s of CPT and changes were lower than in controls ( p<0.05). RMSSD and CV decreased and LF increased significantly only in the controls. We conclude that CPT activates sympathetic HR and BP modulation despite impaired pain and temperature perception in FD patients. BP increase in the presence of almost unchanged SBF might be due to HR increase and to nociceptive arousal and emotionally induced catecholamine release as seen in emotional crises of FD patients. CPT assesses sympathetic cardiovascular responses independently from baroreflex function, which is compromised in FD.

Glucose-induced thermogenesis, inhibition of lipid oxidation rate and autonomic dysfunction in non-diabetic obese women.

The aim of this study was to look for a relationship between autonomic dysfunction and alterations in glucose- induced thermogenesis (GIT) and lipid oxidation rate in obese non-diabetic women. 37 obese women, 20 with impaired cardiac autonomic function tests (group 1) were matched with 17 women with normal tests (group 2) according to age, weight, body mass index (BMI), waist-to-hip ratio (WHR), fat mass (FM) and fat free mass (FFM). A series of five standardized tests was carried out, three of which were based mainly on cardiac parasympathetic control (heart rate response to Valsalva, deep breathing and lying-to-standing) and two on cardiovascular sympathetic function (blood pressure response to standing and to handgrip). Energy expenditure (EE), lipid and glucose oxidation rate were determined by indirect calorimetry at fasting and after an oral glucose load (75 g). Blood glucose, insulin and catecholamines responses to glucose were examined. There was no significant difference in plasma glucose, insulin, catecholamines, metabolic rate, glucose and lipid oxidation rate at fasting and plasma glucose, insulin and catecholamine responses to glucose. GIT was slightly but not significantly lower in group 1 (24.7+/-10.4 kJ) than in group 2 (46.8+/-9.0 kJ). The cumulative glucose oxidation rate did not differ significantly in the two groups. The cumulative lipid oxidation rate was significantly lower in group 1 than in group 2 (-49.4+/-4.1 vs -30.8+/-8.0, respectively, P = 0.033). It correlated negatively with the area under the curve of insulin response (r=-0.37, P=0.04). In the multivariate analysis, both autonomic dysfunction and the area under the curve of insulin response correlated significantly with the cumulative lipid oxidation rate. This study suggests that 1) the glucose-induced inhibition of the lipid oxidation rate in obese women is greater in the patients with autonomic dysfunction; 2) a decrease in sympathetic activity is likely to be involved in this phenomenon.

The effect of ageing on autonomic nervous system function

We studied 76 healthy subjects (five-85 years) with a number of invasive and non-invasive tests of autonomic function. Age related effects were found with the tests of predominantly vagal cardiovascular function. However, there were no age related effects found with the tests of predominantly sympathetic cardiovascular function. The age of the subject should be taken into consideration when evaluating tests of autonomic function and each laboratory should establish its own control values.

Assessment of Cardiovascular Autonomic Functions to Predict Development of Pregnancy Induced Hypertension

Aim: This study aimed at performing autonomic function tests to predict PIH at early stage of pregnancy. Methods: 200 pregnant women between 12 to 20 weeks of gestation were selected for study. Handgrip dynamometer test (HGT) and Cold pressor test (CPT) were performed to assess sympathetic cardiovascular functions. Result: It was observed that 31 women out of 200 pregnant women developed PIH subsequently. ROC curve analysis was done to find out cut off values of high sensitivity and specificity for rise in systolic blood pressure (_SBP) and diastolic blood pressure (_DBP) during CPT and HGT. It was observed that out of 31 women who developed PIH/PE, 87.1% had _SBP _14mm Hg (cut off value) and 83.9% had _DBP _10mm Hg (cut off value) during CPT, both of which were statistically significant (p&lt;0.001). Similarly for HGT, 31 women who developed PIH, _SBP _16 mm Hg and _DBP _14 mm Hg (cut off values) was observed in 96.8% and 83.9% women respectively (p&lt; 0.001). Discriminant analysis showed that the reliability of both the tests in predicting PIH was very high (p&lt;0.001). Conclusion: Thus it can be concluded from the study that heightened blood pressure response to physiological stimuli like cold and isometric exercise early in pregnancy could be used as a suitable tool to predict development of PIH. Key words: Cold pressor test, early detection, Handgrip dynamometer test, PIH DOI: http://dx.doi.org/10.3126/njog.v6i1.5251 NJOG 2011; 6(1): 41-45