Cardiovascular Autonomic Function Tests Research Articles

Retinal Nerve Fiber Layer Loss Is Associated with Urinary Albumin Excretion in Patients with Type 2 Diabetes

To identify the factors associated with retinal nerve fiber layer (RNFL) loss in patients with type 2 diabetes. Cross-sectional study. Ninety-six nonglaucomatous patients with type 2 diabetes without renal impairment (estimated glomerular filtration rate, ≥60 ml/minute per 1.73 m(2)). Eyes were divided into 2 groups based on the presence or absence of RNFL defects detected by red-free retinal fundus photography. All participants underwent an eye fundus examination, and the urinary albumin-to-creatinine ratio (ACR) was determined. A cardiovascular autonomic function test was performed using the following heart rate variability parameters: expiration-to-inspiration ratio, response to the Valsalva maneuver, and standing. Multiple logistic regression analyses were performed to determine potential risk factors related to the presence of RNFL defects in these patients. The association between RNFL defects and diabetic complications. Among the patients, 43 (44.8%) had localized RNFL defects (group 1), whereas the others (55.2%) did not (group 2). The RNFL defects occurred more frequently on the superior side (75.6% and 71.0% in right and left eyes, respectively) compared with the inferior side (13.8% and 0.0% in right and left eyes, respectively). Patients with RNFL defects (group 1) had significantly higher rates of diabetic retinopathy (60.5%) compared with those without RNFL defects (group 2; 32.1%; P = 0.007). The urinary ACR was significantly higher in patients with RNFL defects than in those without defects (45.3±72.1 μg/mg vs. 15.4±17.3 μg/mg creatinine, respectively; P = 0.015), whereas autonomic function test grading was similar between the groups. The urinary ACR was the only factor related to visual field defect location in both univariate (P = 0.021) and multivariate (P = 0.036) logistic regression analyses after adjusting for age; gender; presence of diabetic retinopathy; diabetes duration; smoking; statin use; and antiplatelet, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker treatment. Urinary albumin excretion was associated with nerve fiber layer loss in patients with type 2 diabetes. Careful examination of the optic nerve head may be necessary, particularly in patients with type 2 diabetes exhibiting albuminuria.

The association between abnormal heart rate variability and new onset of chronic kidney disease in patients with type 2 diabetes: A ten-year follow-up study

AimsWe investigated the association between cardiovascular autonomic neuropathy (CAN) and the future development of chronic kidney disease (CKD) in patients with type 2 diabetes. MethodsFrom Jan 2003 to Dec 2004, 1117 patients with type 2 diabetes without CKD (estimated glomerular filtration rate [eGFR]≥60ml/min/1.73m2), aged 25–75 years, were consecutively enrolled. A cardiovascular autonomic function test (AFT) was performed using heart rate variability parameters. The eGFR was measured at least more than once every year, and new onset CKD was defined as eGFR<60ml/min/1.73m2 using a Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. ResultsAmong the 755 (67.6%) patients who completed the follow-up evaluation for 9.6 years, 272 patients (36.0%) showed a CKD stage ≥3. The patients who developed CKD were older, had a longer duration of diabetes, had hypertension, received more insulin and ACE inhibitor/angiotensin receptor blocker (ARB) treatment, and exhibited lower baseline eGFR, HbA1c, and albuminuria levels. Compared to patients without CKD, more patients with CKD at follow-up had CAN at baseline. In a multivariate analysis, after adjustment for age, sex, diabetes duration, presence of hypertension, mean HbA1c, diabetic complications, use of insulin, ACE inhibitor/ARB, statin, and baseline eGFR, the development of CKD was significantly associated with the presence of CAN (HR 2.62, 95% CI 1.87–3.67, P<0.001). ConclusionsIn this prospective, longitudinal, observational cohort study, we demonstrated that diabetic CAN was an independent prognostic factor for the future development of CKD in type 2 diabetes.

Magnitude and pattern of autonomic neuropathy in cirrhosis of liver: A cross-sectional study from central rural India

Background: Cirrhosis of liver is an important cause of morbidity and mortality. Autonomic neuropathy need to be focused as it is independent predictor of mortality with 5-fold increased risk in patients with chronic liver disease (CLD). The aim of the present study was to study the magnitude and pattern of autonomic neuropathy (AN) among subjects with cirrhosis of liver presenting to teaching hospital in central rural India. Methodology: A cross-sectional study was performed in a tertiary care teaching hospital. In all patients of cirrhosis of liver irrespective of etiology, aged 15 and above, underwent clinical assessment and cardiovascular autonomic function tests to confirm autonomic nervous systems damage. We used chi square test to study associations. P value ≤0.05 was considered as significant. Crude odds ratios were computed to assess the strength of association between independent variables and dependent variables along with their 95% confidence intervals. Results: We included 199 cirrhosis of liver patients admitted in medicine department from November 2010 through November 2013. Nearly 83% patients were male and 63.3% patients were under the age of 45 years. Common features present in these patients were ascites (67.8%), splenomegaly (63.5%), pedal edema (60.3%), icterus (45.2%) and gastrointestinal bleeding (39.7%). Among the manifestation of autonomic nerves involvement dizziness on standing was the most common feature in 47.2%, followed by gustatory sweating in 21.6%, and nocturnal diarrhoea in 21.1%. Autonomic neuropathy was found in 70.9% [95% CI: 64.02-77.17] of study subjects on cardiovascular autonomic function tests. Conclusions: Analysis of cardiovascular autonomic function tests shows that the AN is very common in subjects with cirrhosis of liver.

Cardiovascular autonomic neuropathy in rheumatoid arthritis assessed by cardiovascular autonomic function tests: A cross-sectional survey.

Objective:In this study, we aimed to evaluate cardiovascular autonomic neuropathy (CAN) in RA patients by cardiovascular autonomic function tests. Because CAN was reported of patients with automimmune rheumatic diseases those may in sudden death or myocardial infarction.Methods:A total of 44 patients with RA and 44 age-and sex-matched healthy volunteers participated in this cross-sectional study. Assessment of CAN was performed using cardiovascular reflex tests. These five tests were: 1) beat-to-beat heart rate variation during deep breathing; 2) heart rate response to standing up; 3) heart rate response to the Valsalva maneuver; 4) blood pressure response to standing up; and 5) blood pressure response to sustained handgrip.Results:The mean age was 43.15 (SD, 12.18) years (range, 23-68 years) in the RA group, and 38 were women. In beat-to-beat heart rate variation during deep breathing, expiration-to-inspiration ratio was abnormal in 3 cases with RA (6.8%) but in 1 (2.3%) control subject (p=0.3), and maximum minus minimum heart rate was abnormal in 8 patients (18.2%) and in 3 (6.8%) control subjects (p=0.1). 2) In heart rate response to standing up, all patients and controls had normal results. Valsalva ratio was abnormal in 7 RA patients (15.9%) and in 7 control subjects (15.9%). Blood pressure response to standing up was normal in RA patients but abnormal in 1 (2.3%) control subject (p=0.4). Blood pressure response to sustained handgrip was abnormal in 5 RA patients (11.4%) and 2 (4.6%) control subjects (p=0.2).Conclusion:Our study failed to show any statistically significant difference between cardiovascular autonomic function tests in RA patients with control subjects by our test done.

Early Detection of Nerve Fiber Loss by Corneal Confocal Microscopy and Skin Biopsy in Recently Diagnosed Type 2 Diabetes

We sought to determine whether early nerve damage may be detected by corneal confocal microscopy (CCM), skin biopsy, and neurophysiological tests in 86 recently diagnosed type 2 diabetic patients compared with 48 control subjects. CCM analysis using novel algorithms to reconstruct nerve fiber images was performed for all fibers and major nerve fibers (MNF) only. Intraepidermal nerve fiber density (IENFD) was assessed in skin specimens. Neurophysiological measures included nerve conduction studies (NCS), quantitative sensory testing (QST), and cardiovascular autonomic function tests (AFTs). Compared with control subjects, diabetic patients exhibited significantly reduced corneal nerve fiber length (CNFL-MNF), fiber density (CNFD-MNF), branch density (CNBD-MNF), connecting points (CNCP), IENFD, NCS, QST, and AFTs. CNFD-MNF and IENFD were reduced below the 2.5th percentile in 21% and 14% of the diabetic patients, respectively. However, the vast majority of patients with abnormal CNFD showed concomitantly normal IENFD and vice versa. In conclusion, CCM and skin biopsy both detect nerve fiber loss in recently diagnosed type 2 diabetes, but largely in different patients, suggesting a patchy manifestation pattern of small fiber neuropathy. Concomitant NCS impairment points to an early parallel involvement of small and large fibers, but the precise temporal sequence should be clarified in prospective studies.

Morphological and functional parameters of the heart and vessels in patients with type 2 diabetes mellitus and cardiovascular autonomic neuropathy

Objective. To evaluate morphological and functional parameters of the heart and vessels in patients with type 2 diabetes mellitus (DM2) and diabetic cardiovascular autonomic neuropathy (CAN). Materials and methods. A total of 139 patients with DM2 and hypertension (mean age: 53.1?4.9 years; mean duration of hypertension: 9.7?7.8 years) were included in this study. Based on cardiovascular autonomic function test results (electrocardiography, heart rate variability) patients were divided into 2 groups as follows: Group 1 included 40 patients without CAN and Group 2 included 99 patients with CAN. The control group comprised 30 patients with hypertension and normal carbohydrate metabolism (mean age: 53.1?6.0 years; mean duration of hypertension: 10.9?8.5 years). All patients underwent ultrasonography of the heart and common carotid artery. Results. Group 2 patients showed a significant decrease in maximal transmitral flow velocity during early diastolic filling (0.61?0.12 m/s) and a decrease in maximal transmitral flow velocity during late diastolic filling (0.65?0.11 m/s) compared with Group 1 patients (0.66?0.09 m/s and 0.69?0.09 m/s, respectively, р

Cardiovascular autonomic function testing under non-standardised and standardised conditions in cardiovascular patients with type-2 diabetes mellitus.

Autonomic function tests require standardised test conditions. We compared testing under non-standardised and standardised conditions and investigated the agreement between heart and pulse rate variability in 30 subjects with diabetes mellitus. Deep breathing, Valsalva manoeuvre and quick standing tests showed non-standardised reproducibility intraclass correlations (95% CI) of 0.96 (0.82-0.99), 0.96 (0.81-0.99) and 0.75 (-0.98 to 0.94), respectively. Intraclass correlations for sustained handgrip and quick standing were poor. Heart and pulse rate variability showed high-frequency band intraclass correlations (95% CI) of 0.65 (-0.07 to 0.89) and 0.47 (-0.88 to 0.85) for the very low-frequency band, respectively, 0.68 (0.00-0.90) and 0.70 (-0.09 to 0.91) for the low-frequency band, and 0.86 (0.57-0.95) and 0.82 (0.39-0.95) for the high-frequency band. Reproducibility under standardised conditions was comparable. The mean difference (95% limits of agreement) between heart and pulse rate variability was 0.99 (0.80-1.22) for very low frequency, 1.03 (0.88-1.21) for low frequency and 1.35 (0.84-2.16) for high frequency, with a Spearman's correlation coefficient of 1.00, 0.99 and 0.98, respectively. We demonstrated a high agreement between heart and pulse rate variability and acceptable reproducibility with most autonomic function tests, heart and pulse rate variability.

Postural tachycardia syndrome (POTS) and other autonomic disorders in antiphospholipid (Hughes) syndrome (APS)

Antiphospholipid syndrome (APS) is an autoimmune hypercoagulable disorder that has been shown to cause a large number of cardiac and neurological manifestations. Two recent studies have demonstrated abnormalities in cardiovascular autonomic function testing in APS patients without other cardiovascular or autoimmune disease. However, an association between autonomic disorders such as postural tachycardia syndrome and APS has not previously been described. Data were obtained by retrospective chart review. We identified 15 patients who have been diagnosed with APS and an autonomic disorder. The median age of the patients at the time of data analysis was 39 years. The autonomic disorders seen in these patients included postural tachycardia syndrome, neurocardiogenic syncope and orthostatic hypotension. The majority of patients (14/15) were female and the majority (14/15) had non-thrombotic neurological manifestations of APS, most commonly migraine, memory loss and balance disorder. Many also had livedo reticularis (11/15) and Raynaud's phenomenon (nine of 15). In some patients, the autonomic manifestations improved with anticoagulation and/or anti-platelet therapy; in others they did not. Two patients with postural tachycardia syndrome who failed to improve with the usual treatment of APS have been treated with intravenous immunoglobulin with significant improvement in their autonomic symptoms. We believe that autonomic disorders in APS may represent an important clinical association with significant implications for treatment.

Cardiovascular Autonomic Dysfunction Predicts Severe Hypoglycemia in Patients With Type 2 Diabetes: A 10-Year Follow-up Study

OBJECTIVE The aim of this study was to investigate the development of severe hypoglycemia (SH) in the presence of cardiovascular autonomic neuropathy (CAN) in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS From January 2001 to December 2002, a total of 894 patients with type 2 diabetes were enrolled. A cardiovascular autonomic function test (AFT) was performed using the following heart rate variability parameters: expiration-to-inspiration ratio, response to Valsalva maneuver, and standing. From the results for each of the three tests (0 for normal, 1 for abnormal), a total AFT score of 1 was defined as early CAN, and an AFT score of ≥2 was defined as definite CAN. RESULTS The median follow-up time was 9.5 years. The mean age was 54.5 ± 10.1 years, and the mean duration of diabetes was 8.9 ± 6.3 years. One hundred ninety-six patients (31.4%) showed an abnormal cardiovascular AFT score at baseline. Sixty-two patients (9.9%) experienced 77 episodes of SH (1.33 per 100 patient-years). The number of SH events increased as the CAN score increased (23 patients [5.4%] with normal score; 17 patients [17.2%] with early CAN; and 22 patients [22.7%] with definite CAN; P for trends < 0.001). Cox proportional hazards regression analysis revealed that SH was associated with definite CAN (normal vs. definite CAN: hazard ratio 2.43 [95% CI 1.21-4.84]; P = 0.012). CONCLUSIONS Definite CAN was an independent prognostic factor for the development of SH in patients with type 2 diabetes.

Cardiovascular autonomic neuropathy in type 2 diabetes mellitus patients with peripheral artery disease

ObjectiveTo evaluate possible associations between cardiovascular autonomic dysfunction and peripheral artery disease (PAD) in patients with type 2 diabetes mellitus.Research design and methodsIn this cross-sectional study, 67 patients with type 2 diabetes were included. PAD was identified by Doppler ultrasonography: systolic ankle-brachial pressure index <0.9. Cardiovascular autonomic function, besides five conventional cardiovascular autonomic function tests, was assessed by heart rate variability (HRV; 24-h ambulatory ECG recording) in time and frequency domains (spectral analyses) and three dimensional return maps. Power spectral analyses (PSA) were quantified in low frequency (LF), high frequency (HF), and very low frequency.ResultsPatients with PAD (n = 30) had longer diabetes duration, higher systolic blood pressure (BP), waist-to-hip ratio, HbA1C test, and urinary albumin excretion (UAE) than patients without PAD. Most HRV indices in time domain were lower in patients with than without PAD. These patients also had lower PSA indices (LF=0.19±0.07 vs. 0.29±0.11 n.u.; LF/HF ratio=1.98±0.9 vs. 3.35±1.83; P<0.001) and indices of sympathetic (three-dimensional return map: P1-night 61.7±9.4 vs. 66.8±9.7; P=0.04) and vagal (24-h P2 54.5±15.2 vs. 62.7±2.9; P< 0.02) activities (arbitrary units) than patients without PAD. Multivariate logistic regression analyses, adjusted for systolic BP, DM duration, HbA1C test, and UAE, confirmed the associations between impaired autonomic modulation and PAD, except for P1 index.ConclusionIn conclusion, patients with type 2 diabetes with PAD had lower HRV indices than patients without PAD, reflecting a dysfunction of cardiovascular autonomic modulation.

Dysautonomie et troubles urinaires au cours de la sclérose en plaques. Étude clinique, urodynamique et cardiovasculaire

To assess symptoms related to autonomic nervous system alteration in a population of patients suffering from multiple sclerosis (MS) and presenting with urinary symptoms. We investigated 65 patients (mean age 47.5 years) suffering from MS, and presenting with urological dysfunction by means of symptom scores, urodynamic investigation, cardiovascular autonomic function tests (orthostatic hypotension testing, Valsalva test, deep breath test, cold pressor test) and sympathetic skin responses. Forty-five (69%) patients suffered from overactive bladder, 48 (73%) from voiding dysfunction, 14 (21%) from urinary retention and 13 (20%) from fecal incontinence. Urodynamic investigation demonstrated overactive detrusor in 46 (70%) cases, and underactive detrusor in four (6%) cases. Twenty-five (38%) patients had dysautonomia without correlation neither with clinical or urodynamic data, nor gravity of multiple sclerosis (EDSS). In this series, the prevalence of dysautonomia was high in patients suffering from MS and presenting with urinary disorders.

Hyperadrenergic activity and the Postural Tachycardia Syndrome (PoTS)

The aim of this study was to compare cardiovascular autonomic function of Hyperadrenergic PoTS, defined as a plasma norepinephrine &gt;; 600 ng/mol during orthostasis, to PoTS due to other causes. Clinical cardiovascular autonomic function test results were reviewed. 50 PoTS patients were identified; 18 with Hyperadrenergic PoTS. Plasma norepinephrine was higher while upright (383 ± 99 vs 726 ± 112 ng/mol, p&lt;0.05) and supine (233 ± 58 vs 422 ± 128 ng/mol, p&lt;0.05) in Hyperadrenergic PoTS. There were no differences in heart rate or blood pressure during cold pressor challenge, mental stress, isometric exercise, deep breathing and short‐term (9 min) head‐up tilting, between groups (all p&gt;;0.05). Valsalva manoeuvre derived Valsalva ratio, blood pressure recovery time and vagal baroreflex sensitivity were not different (all p&gt;;0.05), whereas adrenergic baroreflex sensitivity was lower in Hyperadrenergic PoTS (p&lt;0.05). Hyperadrenergic PoTS had lower prolonged (60 min or less) head‐up tilt tolerance (p&lt;0.05); termination was predominantly due to patient request not differences in heart rate or blood pressure. These findings suggest that, 1) Hyperadrenergic PoTS have elevated supine and upright, plasma norepinephrine levels and 2) Hyperadrenergic PoTS do not have distinctive cardiovascular autonomic function except for decreased adrenergic baroreflex sensitivity and reduced prolonged orthostatic tolerance.

Cardiac autonomic dysfunction in sickle cell anaemia and its correlation with QT parameters

Background:Abnormalities of QT parameters together with cardiac autonomic neuropathy (CAN) confer significant risks of cardiac morbidity and mortality in patients with diabetes mellitus. We questioned whether or not CAN influences occurrence of QT interval prolongation and dispersion in patients with sickle cell anaemia (SCA).Materials and Methods:Forty stable adult sickle cell patients with 44 healthy haemoglobin AA controls were studied. Baseline electrocardiograms were obtained and cardiovascular autonomic function tests were performed using standard protocols.Results:Mean corrected QT (QTc) in sickle cell patients was significantly higher (P = 0.001) than the mean of controls. Similarly, mean QT dispersion (QTcd) was higher (P = 0.001) in the former than in the latter. Mean QTc in patients with CAN was longer than patients with normal autonomic function (461 ± 26 ms versus 411 ± 23 ms), P = 0.001 (OR of 17.1, CI 3.48–83.71). Similarly, QTcd was higher (P = 0.001) in patients with CAN than those with normal cardiac autonomic function. Positive correlations were found between CAN with QTc and QTcd (r = 0.604, P = 0.001, r = 0.523, P = 0.001, respectively).Conclusion:CAN is a risk factor for abnormalities of QT parameters in SCA and both may be harbinger for cardiac death.

The effect of smoking on the cardiovascular autonomic functions: a cross sectional study.

Smoking is a worldwide major cause of preventable morbidity and mortality. Smoking affects the cardiovascular system by several mechanisms. The present study was planned to study the effect of smoking on the cardiovascular autonomic functions among smokers. Hundred male subjects who were in the age group of 25 to 40 years, who included 50 smokers and 50 non - smokers who formed the control group were selected for the present study. The participant subjects were selected from among the staff members, residents and the patients from the routine OPD. Prior informed written consents were obtained from them after explaining to them, the procedure and the purpose of the study tests. The Cardiovascular Autonomic Function Tests were assessed by using a CANWIN AUTONOMIC ANALYSER which was available in the department. After applying the 'Z'-test for the difference between the two sample means, it was observed that there was a highly significant difference between the mean values of the para-sympathetic function tests among the smokers and the non - smokers (i.e. p<0.01) The Resting Heart Rate had significantly increased and the Expiration: Inspiration Ratio, the 30:15 Ratio (Response to standing) and the Valsalva Ratio had significantly decreased in the smokers as compared to those in the non - smokers. After applying the 'Z'-test for the difference between the two sample means, it was observed that there was no significant difference between the mean values of the Postural hypotension test (i.e. p>0.05) and that there was a highly significant difference between the mean values of the Sustained handgrip test in the smokers and the non - smokers (i.e. p<0.01).

A Comparative Study of Cardiovascular Autonomic Function Tests in Yoga Practitioners and Controls

Background: In the present age, a great emphasis is being laid on the practice of yogic postures as a form of highly effective physical exercise for keeping the body healthy and also for the control of disease process. Rhythmic breathing controls the mind, lungs and heart which are located in the thoracic cage and are under the control of autonomic nervous system. The aim of this study was to evaluate the cardiovascular autonomic function tests among yoga practitioners. Method: 75 healthy volunteers (aged 18-31 years)were divided in to three groups; the first two yoga groups ( each group ,n=25 ) consisted of subjects who were practicing the yoga (pranayama and suryanamaskarams) for less than 2 years and more than 2 years, respectively and the third group was controls (n=25). Autonomic function tests were performed for both sympathetic and parasympathetic activity ,which include deep breathing test, valsalva maneuver, heart rate response to standing posture (30:15 ratio) , orthostatic hypotension test and sustained hand grip test. Results: The statistics showed a significant value for heart rate variability , 30:15 ratio ,hand grip test, othrostatic hypotension test and valsalva ratio in group 1 and 2 yoga practitioners (p<0.05) than in controls. But no significant difference observed in terms of resting heart rate in all groups. The overall ewing's autonomic dysfunction score was high in controls compared to yoga practicing subjects ((p<0.05). Conclusion: It is evident that yoga develops an ability to control cardiovascular autonomic functions and would prepare the body to overcome stress by modulating and optimizing sympathetic activities.

OP11: Metabolic and vascular determinants of increased left ventricular torsion in patients with type 2 diabetes mellitus

Left ventricular torsion is increased in uncomplicated type 2 diabetes (T2DM) which may be an early manifestation of cardiomyopathy. Our aim was to evaluate the relationship of torsion to energetic impairment and microvascular damage in healthy patients with T2DM. 36 patients with T2DM without coronary artery disease as measured by a normal dobutamine stress echocardiography and 20 healthy control (HC) subjects were recruited. Magnetic resonance spectroscopy, standard, speckle tracking and contrast echocardiography, cardiovascular autonomic function (CAN) testing and skin endothelial poly (ADP-ribose) polymerase assessments were performed. Left ventricular (LV) torsion was increased in subjects with T2DM (2.6 ± 0.8°/cm) compared to HC (2.0 ± 0.5°/cm, p=0.002). Cardiac energetics were reduced in patients with T2DM compared to HC (1.1 ± 0.4 vs. 1.8 ± 0.5, p<0.0001), but were not associated with increased torsion. Endothelial PARP was increased by 19% (p=0.0001) in subjects with T2DM and correlated with LV apical rotation ((R Square 0.424 p=0.017) after adjustment for weight and BMI. Torsion correlated significantly with CAN (F(2, 31) = 3.5, p=0.043, eta square 0.2). LV torsion is increased in healthy T2DM. Microvascular damage and autonomic dysfunction but not reduced cardiac energetics may play an important pathophysiological role in its development.

Direct renin inhibition improves parasympathetic function in diabetes

The renin-angiotensin-aldosterone system (RAAS) and autonomic nervous system regulate the cardiovascular system. Blockade of the RAAS may slow the progression of end-organ damage. Direct renin inhibition offers a means for blocking the RAAS. The objective of this study was to examine the effect of direct renin inhibition on cardiovascular autonomic function. In this double-blind, placebo-controlled trial, 60 individuals with diabetes were randomly assigned to 300 mg of aliskiren or placebo once daily for 6 weeks. The primary end point was a change in tests of cardiovascular autonomic function. Autonomic function was assessed by power spectral analysis and RR-variation during deep breathing [i.e. mean circular resultant (MCR), expiration/inspiration (E/I) ratio]. The MCR and E/I ratio assess parasympathetic function. Secondary measures included change in biochemical parameters [e.g. plasma renin activity, leptin and interleukin-6]. Change in cardiovascular autonomic function and blood analytes were analysed by a mixed effects model for repeated measures. Baseline characteristics were similar between treatment groups. In response to aliskiren compared with placebo, blood pressure was reduced as well as plasma renin activity [from 2.4 ± 3.8 (mean ± standard deviation) to 0.5 ± 0.4 µg/l/h, p < 0.001]. There was a significant interaction (aliskiren × visit) for MCR (p = 0.003) and E/I ratio (p = 0.003) indicating improvement in MCR and E/I ratio for those on aliskiren. MCR means, baseline vs. follow-up, were 41.8 ± 19.7 vs. 50.8 ± 26.1 (aliskiren) and 38.2 ± 23.6 vs. 37.5 ± 24.1 (placebo). Parasympathetic function (i.e. MCR and E/I ratio) was enhanced by downregulation of the RAAS.

Cardiovascular autonomic function and vibration perception threshold in type 2 diabetes mellitus

ObjectiveThe aim of this study was to compare cardiovascular autonomic function tests (AFT) and vibration perception threshold (VPT) of patients with type 2 diabetes mellitus (T2DM) with controls. Research Design/MethodsThe study was conducted on 60 diabetic patients comparing with 30 controls. The cardiovascular AFT and VPT were assessed in both groups. ResultsAmong cardiovascular AFT, E:I ratio [1.24 (1.2–1.32) vs 1.3 (1.24–1.4), p=0.001], and Valsalva ratio [1.28 (1.22–1.4) vs 1.6 (1.5–1.73), p=0.001], the indicators of parasympathetic reactivity were reduced in T2DM. Rise in DBP during handgrip, an indicator of sympathetic reactivity was lower in T2DM [12 (10–14) vs 16 (14–18) mmHg, p=0.001] whereas, fall in SBP during head up tilt [4 (4–8) vs 5 (4–8) mmHg] was comparable. VPT (somatic sensation) was comparable between T2DM and control. ConclusionAutonomic involvement is more marked than somatic, and parasympathetic involvement is more marked than the sympathetic, possibly reflecting severity and chronological pattern of their involvement.

Alterations in cardiovascular autonomic function tests in idiopathic hyperhidrosis

We performed cardiovascular autonomic function tests to assess sympathetic and parasympathetic functions in patients with idiopathic hyperhidrosis.We studied 35 patients with idiopathic hyperhidrosis and 35 age- and sex-matched controls. A thermoregulatory sweat test (TST) was performed in all subjects. Sweating was qualitatively (Minor's test at 22°C) and quantitatively (skin conductance) evaluated. Orthostatism, tilt to 65°, cold pressor test, deep breathing, Valsalva maneuver and hyperventilation were performed in patients and controls.A greater fall in blood pressure values was observed in patients than in controls in the upright tests (p<0.05). In particular, postural hypotension was present in a subgroup of patients (34%), in whom changes in lying-to-standing blood pressure and heart rate were greater (p<0.001) than those of the remaining patients. The TST revealed that the total body sweat rate (ml/cm²/min) was more pronounced in patients with postural hypotension (p<0.001) than in the other patients and controls. The skin conductance values of patients with postural hypotension were higher (p<0.001) than those of the remaining patients. A positive correlation was found between skin conductance values and postural hypotension. Dehydration and poor water intake may play a role in postural hypotension in patients with severe hyperhidrosis and pronounced thermoregulatory sweating.A significantly marked increase in parasympathetic function was observed in patients. Responses to deep breathing, Valsalva maneuver and hyperventilation were significantly greater in patients (p<0.001) than in controls.Idiopathic hyperhidrosis seems to be a complex dysfunction that involves autonomic pathways other than those related to sweating.

Relationship between cardiovascular autonomic (dys)function and microalbuminuria in type 2 Diabetes Mellitus

Background: Diabetic autonomic neuropathy is a serious and common complication of diabetes mellitus and in fact it is one of the most overlooked complications, thus very limited clinical and research data are available on early renal and cardiovascular autonomic complications in type 2 diabetes mellitus. Aims & Objective: To determine the possible association of elevated albumin excretion rate with cardiovascular autonomic activity in type 2 diabetes mellitus. Materials and methods: A cross-sectional study was conducted with one hundred and fifteen patients of type 2 diabetes mellitus. Microalbuminuria was defined as Albumin Excretion Rate (AER) > 30 mg/24 hr in an early morning urine sample. Nine parameters reflecting different aspects of cardiovascular autonomic function were measured and were summarized in a single cardiovascular autonomic function score (CAFS).The association between cardiovascular autonomic dysfunction and microalbuminuria was estimated by multiple linear regressions. Results: Patients with microalbuminuria had low levels of the autonomic function parameters i.e. mean CAFS, indicating impaired autonomic function. This association was consistent with increasing AER, and remained significant after multivariate adjustment for other clinical factors predictive of microalbuminuria. In additional analysis, we examined the autonomic function tests combined on the part of autonomic nervous system they predominantly represent. The results of these alternative combinations were comparable to those of the CAFS score. Conclusion: Cardiovascular autonomic dysfunction was independently associated with microalbuminuria in patients with type 2 diabetes mellitus, and that this association is independent of other previously identified determinants of albuminuria in type 2 diabetes mellitus. Therefore cardiovascular autonomic function tests should be monitored to pay attention to major potential cardiovascular complications even in asymptomatic patients, but especially among those with microalbuminuria.