Tests for early diagnosis of cardiovascular autonomic neuropathy: critical analysis and relevance

Heart Rate Variability in Patients of Ankylosing Spondylitis: A Systematic Review and Meta-Analysis

Patients with ankylosing spondylitis (AS) have a significantly higher risk of cardiovascular morbidities. The participation of the autonomic nervous system (ANS) in AS is still unknown and inconclusive. Heart rate variability (HRV) is defined as the variability of the time interval between two consecutive heartbeats. This meta-analysis aims to detect the association of HRV and its various parameters with AS patients by comparing them to healthy controls. Research literature was searched in PubMed, Embase, and Cochrane Library databases from inception to April 2022. The Review Manager 5 (RevMan) Version 5.4 software was used to analyze the data. In addition, the protocol of systematic review is registered in the PROSPERO database with ID CRD42022336484. This study includes a total of nine case-control studies with a total of 923 patients; 409 with AS and 514 healthy controls. The root mean square of successive differences between normal heartbeats (RMSSD) [standardized mean difference (SMD); -0.47, 95% CI: -0.69 to -0.25, p < 0.0001], proportion of NN50 (pNN50) (SMD; -0.89, 95% CI: -1.74 to -0.04, p = 0.04) and HRV (SMD; -1.11, 95% CI: -1.53 to 0.69, P < 0.00001) were significantly low in AS cases compared to healthy controls. The HRV value was also significantly low in patients with high Bath ankylosing spondylitis disease activity (BASDAI) index (SMD: -1.45, 95% CI: -2.45 to -0.36, p < 0.009). HRV (parasympathetic activity) was significantly lowered in AS patients compared to healthy controls.

Severe bradycardia and hypotension induced by autonomic neuropathy in a diabetic patient during general anesthesia - A case report

Cardiovascular autonomic neuropathy (CAN) is characterized by dysregulation of sympathetic and parasympathetic nervous systems that causes cardiovascular and respiratory disorders. The number of diabetic patients undergoing surgery is increasing in line with the prevalence of DM. Anesthesiologists should pay attention to diabetic patients with CAN because it is related to serious cardiovascular morbidity and mortality. We report an 80-year-old male who underwent cervical laminoplasty. He had severe bradycardia and hypotension from induction to the suspension of surgery. His blood pressure dropped to 70/40 mmHg and his heart rate to 20 bpm. Ephedrine, phenylephedrine, and atropine administration had minimal effect, but after epinephrine administrations, his heart rate and blood pressure increased to 70 bpm and 170/90 mmHg. The operation was discontinued because of the patient's unstable, fluctuating vital signs. The results of autonomic nervous system function examination indicated postganglionic cholinergic sympathetic dysfunction, sympathetic adrenergic dysfunction, and parasympathetic cholinergic dysfunction.

Complexity Analysis in the PR, QT, RR and ST Segments of ECG for Early Assessment of Severity in Cardiac Autonomic Neuropathy

Early-stage detection of cardiac autonomic neuropathy (CAN) is important for better management of the disease and prevents hospitalization. This study has investigated the complex nature of PR, QT, RR, and ST time segments of ECG signals by computing the fractal dimension (FD) of all segments from 20 min ECG recordings of people with different severity of the disease and healthy individuals. The mean computed for each ECG time segment to distinguish between subjects was insufficient for an early diagnosis. Statistical analysis shows that the change of FD in various time segments of ECG throughout the recording was most suitable to assess the steps for severity in symptoms of CAN between the healthy and the subjects with early symptoms of CAN. The complexity of ECG features was evaluated using various classifier models, namely, support vector machine (SVM), naïve Bayes, random forest, K-nearest neighbor (KNN), AdaBoost, and neural networks. Performance measures were computed on all models, with a maximum neural network classifier having an accuracy of 96.9%. Feature ranking results show that fractal features have more significance than the time segments of ECG in differentiating the subjects. The results of statistical validation show that all the selected features based on ECG physiology proved to have an evident complexity change between normal and severity stages of CAN. Thus, this work reports the complexity analysis in all the selected time segments of ECG that can be an effective tool for early diagnostics for CAN.

Immediate effect of cold mud pack therapy on autonomic variables in primary hypertensive individuals: a randomized trial

OBJECTIVES

Mud pack or compress is an easily accessible, cost-effective, efficient treatment modality used in naturopathy to manage and prevent various chronic illnesses. This study sought to elucidate the effectiveness of cold spinal mud packs on improving neuro-cardiac parameters among hypertensive individuals.

METHODS

A total of 100 hypertensive subjects aged 30-50 years were randomly allocated into two groups: Cold spinal mud pack (CSMP) and prone rest. Blood Pressure (BP) and Heart Rate Variability (HRV) were assessed at three-time points: Baseline, After 20 min (T1), After 60 min (T2). This single-blinded randomized controlled trial was registered in the Clinical Trials Registry-India (CTRI/2019/12/022492).

RESULTS

After 20 min of CSMP showed a statistically significant reduction (p<0.01) in mean values of Systolic BP, Diastolic BP, and in HRV attained statistically significant change (p<0.01) in mean score in the frequency domain except for Very low-frequency power (VLF) and a significant difference found in the mean score of time-domain values (p<0.01) when compared to control group and 95% confidence interval (CI) will be provided for each effect.

CONCLUSIONS

CSMP reduces the sympathetic tone and shifts the sympathovagal balance in favor of parasympathetic dominance, contributing to a decrease in BP and effective changes in components of HRV.

Cardiovascular autonomic neuropathy in diabetes: Pathophysiology, clinical assessment and implications

Cardiovascular autonomic neuropathy (CAN) is a debilitating condition that mainly occurs in long-standing type 2 diabetes patients but can manifest earlier, even before diabetes is diagnosed. CAN is a microvascular complication that results from lesions of the sympathetic and parasympathetic nerve fibers, which innervate the heart and blood vessels and promote alterations in cardiovascular autonomic control. The entire mechanism is still not elucidated, but several aspects of the pathophysiology of CAN have already been described, such as the production of advanced glycation end products, reactive oxygen species, nuclear factor kappa B, and pro-inflammatory cytokines. This microvascular complication is an important risk factor for silent myocardial ischemia, chronic kidney disease, myocardial dysfunction, major cardiovascular events, cardiac arrhythmias, and sudden death. It has also been suggested that, compared to other traditional cardiovascular risk factors, CAN progression may have a greater impact on cardiovascular disease development. However, CAN might be subclinical for several years, and a late diagnosis increases the mortality risk. The duration of the transition period from the subclinical to clinical stage remains unknown, but the progression of CAN is associated with a poor prognosis. Several tests can be used for CAN diagnosis, such as heart rate variability (HRV), cardiovascular autonomic reflex tests, and myocardial scintigraphy. Currently, it has already been described that CAN could be detected even during the subclinical stage through a reduction in HRV, which is a non-invasive test with a lower operating cost. Therefore, considering that diabetes mellitus is a global epidemic and that diabetic neuropathy is the most common chronic complication of diabetes, the early identification and treatment of CAN could be a key point to mitigate the morbidity and mortality associated with this long-lasting condition.

Streptozotocin-induced type 1 and 2 diabetes in rodents: a model for studying diabetic cardiac autonomic neuropathy

Background

Several animal models are continually being developed to study diabetic complication. Several conflicting regimen for diabetes induction exist in the literature with varying dose strength and regimen for different study interest in diabetes. This study aims to show the effect of high dose streptozotocin (STZ) on the one hand compared with multiple low doses after high fat diet induction on diabetic cardiac autonomic neuropathy (DCAN).

Methodology

Eighty-four Wistar rats were used to demonstrate DCAN induction using 2 approaches one for T1DM (STZ 50mg/kg) and the other for T2DM (HFD for 8 weeks with STZ 25mg/Kg daily for five days). DCAN features were assessed using invasive biomarkers, histology patterns and cardiac nerve densities.

Results

Diabetes induction rate was 76% and 89% in T1DM and T2DM model respectively. T1DM group had significant weight loss, reduced c-peptide, and insulin level post induction. The T2DM additionally showed significantly higher total cholesterol and Homeostatic model assessment (HOMA) compared with control. Serum levels of catecholamine, choactase, nerve growth factor and cardiac nerve density confirms development of DCAN.

Conclusion

High single dose of STZ and HFD with multiple low doses of STZ may be recommended for DCAN study in T1DM and T2DM rat model respectively.

Carvedilol improves heart rate variability indices, biomarkers but not cardiac nerve density in streptozotocin-induced T2DM model of diabetic cardiac autonomic neuropathy

OBJECTIVES

There has been increasing recognition of the significant relationship between the autonomic nervous system and cardiovascular sequel in diabetes mellitus (DM) patients. Diabetic cardiac autonomic neuropathy (DCAN) still poses a treatment challenge in the clinical settings despite several research interventions. This study was designed to investigate the effect of carvedilol on experimentally induced DCAN in type 2 DM rat model.

METHODS

DCAN was induced in 42 Wistar rats using high fat diet (HFD) for eight weeks, thereafter streptozotocin (STZ) at 25 mg/kg daily for five days. DCAN features were then assessed using non-invasive time and frequency varying holter electrocardiogram (ECG), invasive biomarkers, cardiac histology and cardiac nerve density.

RESULTS

Carvedilol significantly ameliorated the effects of DCAN on noradrenaline (p=0.010) and advanced glycated end products (AGEs) (p<0.0001). Similarly, carvedilol reversed the reduction in levels of antioxidants, sorbitol dehydrogenase (SD) activity (p=0.009) nerve growth factors (p<0.0001) and choline acetyl-transferase (p=0.031) following DCAN induction. Furthermore, heart rate variability (HRV) indices which were also reduced with DCAN induction were also ameliorated by carvedilol. However, carvedilol had no significant effect on cardiac neuronal dystrophy and reduced cardiac nerve densities.

CONCLUSIONS

Carvedilol improves physiological HRV indices and biomarkers but not structural lesions. Early detection of DCAN and intervention with carvedilol may prevent progression of autonomic neurologic sequel.

Awareness of hypoglycemia and spectral analysis of heart rate variability in type 1 diabetes

AIMS

To investigate the relationship of unawareness of hypoglycemia with spectral analysis of heart rate variability (HRV) and clinical variables in type 1 diabetes (T1D) individuals.

METHODS

Participants with type 1 diabetes mellitus (type 1 diabetes) were prospectively assessed for hypoglycemia awareness using the Pedersen-Bjergaard method and were classified as normal hypoglycemia awareness, impaired hypoglycemia awareness and hypoglycemia unawareness. Indices of HRV in frequency domain were evaluated and Ewing tests were used for the diagnosis of cardiovascular autonomic neuropathy (CAN).

RESULTS

Ninety-eight participants with T1D (mean age 26 years, average diabetes duration 13 years, and mean HbA1c 8.4%) were included in this study. The prevalence of hypoglycemia unawareness was 28%. No significant difference was observed on the prevalence of CAN among groups of different hypoglycemia awareness (p = 0.740). On regression analyses, abnormal results of HRV in frequency domain were not associated with unawareness of hypoglycemia. On univariable regression analysis, age, diabetes duration and estimated creatinine clearance were associated with unawareness of hypoglycemia.

CONCLUSION

CAN as assessed by Ewing tests and spectral analysis of HRV is not associated with unawareness of hypoglycemia. There is association of age, diabetes duration and renal deficit with unawareness of hypoglycemia.

Severity of Cardiovascular Autonomic Neuropathy Is a Predictor Associated With Major Adverse Cardiovascular Events in Adults With Type 2 Diabetes Mellitus: A 6-Year Follow-up Study

OBJECTIVES

Cardiovascular autonomic function impairment has been reported in patients with type 2 diabetes mellitus and is associated with cardiovascular events. In this study, we test the hypothesis that the severity of cardiovascular autonomic neuropathy is a predictor associated with subsequent 3-point major adverse cardiovascular events (3-P MACE; combined endpoint of cardiovascular death, nonfatal myocardial infarction and nonfatal stroke).

METHODS

In this prospective study, we enrolled 168 patients with type 2 diabetes mellitus over a 6-year follow-up period. We constructed the Composite Autonomic Scoring Scale as a measure of the severity of cardiovascular autonomic neuropathy and examined baseline clinical and laboratory data of 168 patients with diabetes. Cardiovascular autonomic testing included heart rate response to deep breathing, Valsalva ratio and baroreflex sensitivity. Therapeutic outcome was defined as 3-P MACE.

RESULTS

The overall incidence of new 3-P MACE was 23.2% and overall fatality rate was 9.5% during the 6-year follow-up period. Only underlying coronary heart disease and Composite Autonomic Scoring Scale were independently associated with subsequent 3-P MACE in the Cox proportional hazards model. Any increase of 1 point in Composite Autonomic Scoring Scale would increase the risk of new 3-P MACE by 9.7%. Area under the curve on receiver-operating characteristic curve analysis was 0.72 in predicting subsequent 3-point MACE in combined heart rate response to deep breathing and Valsalva ratio.

CONCLUSIONS

Besides underlying coronary heart disease, the severity of cardiovascular autonomic neuropathy is strongly associated with subsequent 3-P MACE. Combined heart rate response to deep breathing and Valsalva ratio testing can increase sensitivity and specificity in predicting subsequent 3-point MACE, and it can serve as a time-effective cardiovascular autonomic screening service in the outpatient clinic sitting.

The relationship between glycaemic variability and cardiovascular autonomic dysfunction in patients with type 1 diabetes: A systematic review

Rigorous glycaemic control-reflected by low HbA1c goals-is of the utmost importance in the prevention and management of complications in patients with type 1 diabetes mellitus (T1DM). However, previous studies suggested that short-term glycaemic variability (GV) is also important to consider as excessive glucose fluctuations may have an additional impact on the development of diabetic complications. The potential relationship between GV and the risk of cardiovascular autonomic neuropathy (CAN), a clinical expression of cardiovascular autonomic dysfunction, is of increasing interest. This systematic review aimed to summarize existing evidence concerning the relationship between GV and cardiovascular autonomic dysfunction in T1DM. An electronic database search of Medline (PubMed), Web of Science and Embase was performed up to October 2019. There were no limits concerning year of publication. Methodological quality was evaluated using the Newcastle Ottawa Scale for observational studies. Six studies (four cross-sectional and two prospective cohorts) were included. Methodological quality of the studies varied from level C to A2. Two studies examined the association between GV and heart rate variability (HRV), and both found significant negative correlations. Regarding cardiovascular autonomic reflex tests (CARTs), two studies did not, while two other studies did find significant associations between GV parameters and CART scores. However, associations were attenuated after adjusting for covariates such as HbA1c, age and disease duration. In conclusion, this systematic review found some preliminary evidence supporting an association between GV and cardiovascular autonomic dysfunction in T1DM. Hence, uncertainty remains whether high GV can independently contribute to the onset or progression of CAN. The heterogeneity in the methodological approach made it difficult to compare different studies. Future studies should therefore use uniformly evaluated continuous glucose monitoring-derived parameters of GV, while standardized assessment of HRV, CARTs and other potential cardiac autonomic function parameters is needed for an unambiguous definition of CAN.

Heart rate variability indices, biomarkers, and cardiac nerve density: Independent surrogate markers for diagnosis of diabetic cardiac autonomic neuropathy in type 2 diabetes mellitus animal model

OBJECTIVES

Heart rate variability (HRV) has been shown to represents a promising quantitative marker of autonomic activity. Studies have shown that diabetic patients and animal models have derangements in certain biochemical parameters with reduced cardiac nerve density following development of diabetic cardiac autonomic neuropathy (DCAN). This study, therefore, aims to correlate HRV indices, cardiac histology, and cardiac nerve density with selected biochemical markers in the DCAN rat model using high fat diet (HFD) and streptozotocin (STZ) induction.

METHODS

DCAN was induced in Wistar rats using HFD for 8 weeks with 25 mg/kg STZ daily for 5 days. DCAN features were then assessed using Holter electrocardiography (ECG), invasive biomarkers, and cardiac histology.

RESULTS

DCAN group had significantly higher advanced glycated end product levels (P < 0.0001), noradrenaline (P = 0.010), and insulin resistance (P = 0.016) compared with controls. The level of antioxidants, sorbitol dehydrogenase activity (P = 0.009), nerve growth factors (P < 0.0001), and choline acetyl-transferase (P = 0.031) was, however, significantly reduced. Furthermore, HRV indices which were also reduced with DCAN induction correlated significantly with levels of biomarkers and cardiac nerve density.

CONCLUSION

HRV is a cheap and easy tool for assessing DCAN that significantly correlates with markers of autonomic activity. Holter ECG and HRV evaluation should be considered early in patients with diabetes.

Architecture of the Cutaneous Autonomic Nervous System

The human skin is a highly specialized organ for receiving sensory information but also to preserve the body's homeostasis. These functions are mediated by cutaneous small nerve fibers which display a complex anatomical architecture and are commonly classified into cutaneous A-beta, A-delta and C-fibers based on their diameter, myelinization, and velocity of conduction of action potentials. Knowledge on structure and function of these nerve fibers is relevant as they are selectively targeted by various autonomic neuropathies such as diabetic neuropathy or Parkinson's disease. Functional integrity of autonomic skin nerve fibers can be assessed by quantitative analysis of cutaneous responses to local pharmacological induction of axon reflex responses which result in dilation of cutaneous vessels, sweating, or piloerection depending on the agent used to stimulate this neurogenic response. Sensory fibers can be assessed using quantitative sensory test. Complementing these functional assessments, immunohistochemical staining of superficial skin biopsies allow analysis of structural integrity of cutaneous nerve fibers, a technique which has gained attention due to its capacity of detecting pathogenic depositions of alpha-synuclein in patients with Parkinson's disease. Here, we reviewed the current literature on the anatomy and functional pathways of the cutaneous autonomic nervous system as well as diagnostic techniques to assess its functional and structural integrity.

HbA1C Variability Is Strongly Associated With the Severity of Cardiovascular Autonomic Neuropathy in Patients With Type 2 Diabetes After Longer Diabetes Duration

Background

Variability in the glycated hemoglobin (HbA1c) level is associated with a higher risk of microvascular complications in patients with type 2 diabetes. We tested the hypothesis that HbA1c variability is not only strongly associated with the presence but also the degree of severity of cardiovascular autonomic neuropathy (CAN) in patients with long diabetes durations (more than 10 years).

Methods

For each patient, the intrapersonal mean, standard deviation (SD), and coefficient of variation (CV) for HbA1c were calculated using all measurements obtained 3 years before the study. We constructed the composite autonomic scoring scale (CASS) as a measure of the severity of cardiovascular autonomic functions. Stepwise logistic regression and linear regression analyses were performed to evaluate the presence of CAN and the influence of independent variables on the mean CASS, respectively.

Results

Those with CAN had a higher mean age, a higher low-density lipoprotein cholesterol (LDL-C), HbA1c-SD, HbA1c-CV, mean HbA1c, and index HbA1c, higher prevalence of retinopathy as the underlying disease, and lower high-density lipoprotein (HDL) levels. Stepwise logistic regression showed that HbA1c-SD and retinopathy were risk factors that were independently associated with the presence of CAN. Mean HbA1c, HbA1c-CV, HbA1c-SD, and index HbA1c were positively correlated with mean CASS, and a multiple linear regression analysis revealed that HbA1c-SD was independently associated with the mean CASS.

Conclusion

HbA1c variability is strongly associated with not only the presence but also the degree of severity of CAN. A longitudinal study is required to confirm whether controlling blood glucose level is effective in reducing CAN progression.

Cardiac Autonomic Neuropathy in Diabetes Mellitus

Cardiovascular autonomic neuropathy (CAN) is a severely debilitating yet underdiagnosed condition in patients with diabetes. The prevalence can range from 2.5% (based on the primary prevention cohort in the Diabetes Control and Complications Trial) to as high as 90% of patients with type 1 diabetes. Clinical manifestations range from orthostasis to myocardial infarction. The diagnosis is made using multiple autonomic function tests to assess both sympathetic and parasympathetic function. The pathophysiology of CAN is complex, likely multifactorial, and not completely understood. Treatment is limited to symptomatic control of orthostatic hypotension, which is a late complication, and current strategies to reverse CAN are limited. This review explores the epidemiology, pathophysiology, clinical manifestations, diagnosis, and complications of CAN as well as current treatment options.

Cystatin C Is an Important Biomarker for Cardiovascular Autonomic Dysfunction in Chinese Type 2 Diabetic Patients

BACKGROUND

Cardiovascular autonomic dysfunction is closely related to increased mortality in patients with diabetes. Previous studies have proved that cystatin C (CysC) is an important predictor of both peripheral neuropathy and cardiovascular events. However, whether CysC is also associated with cardiovascular autonomic dysfunction remains unclear. Therefore, the aim of this study was to investigate the relationship between CysC and cardiovascular autonomic dysfunction in type 2 diabetic patients without renal dysfunction.

METHODS

A total of 161 type 2 diabetic patients with normal serum creatinine (less than 133 μmol/l) and estimated glomerular filtration rate (eGFR) higher than 60 ml/min per 1.73 m² were recruited in our study. Cardiovascular autonomic dysfunction was determined by heart rate variability (HRV) measured by a 24-hour Holter monitor. Serum CysC was tested by particle-enhanced turbidimetric immunoassay, and subjects were divided into three groups based on the tertiles of CysC. Pearson correlation analysis was used to evaluate the association between different indexes, and the association of CysC with HRV indexes was assessed by multivariate linear regression analysis.

RESULTS

The HRV parameters were lower in the group with the highest CysC concentration than in the groups with lower levels of CysC (P < 0.05). Pearson correlation analysis showed a negative relationship between CysC and the HRV parameters, including SDNN (r = -0.31, P < 0.001), SDANN (r = -0.25, P = 0.002), and logLF (r = -0.18, P = 0.023). Furthermore, multivariate linear regression analysis revealed that CysC was independently correlated with SDNN (β = -24.11, P = 0.015) and SDANN (β = -19.88, P = 0.047) after adjusting for the confounding factors of gender, age, blood pressure, body mass index, eGFR, and hemoglobin A1c.

CONCLUSIONS

Serum CysC levels are associated with cardiovascular autonomic dysfunction; furthermore, CysC may be a reliable and convenient biomarker for detecting cardiovascular autonomic dysfunction.

Cardiac autonomic neuropathy: Risk factors, diagnosis and treatment

Cardiac autonomic neuropathy (CAN) is a serious complication of diabetes mellitus (DM) that is strongly associated with approximately five-fold increased risk of cardiovascular mortality. CAN manifests in a spectrum of things, ranging from resting tachycardia and fixed heart rate (HR) to development of “silent” myocardial infarction. Clinical correlates or risk markers for CAN are age, DM duration, glycemic control, hypertension, and dyslipidemia (DLP), development of other microvascular complications. Established risk factors for CAN are poor glycemic control in type 1 DM and a combination of hypertension, DLP, obesity, and unsatisfactory glycemic control in type 2 DM. Symptomatic manifestations of CAN include sinus tachycardia, exercise intolerance, orthostatic hypotension (OH), abnormal blood pressure (BP) regulation, dizziness, presyncope and syncope, intraoperative cardiovascular instability, asymptomatic myocardial ischemia and infarction. Methods of CAN assessment in clinical practice include assessment of symptoms and signs, cardiovascular reflex tests based on HR and BP, short-term electrocardiography (ECG), QT interval prolongation, HR variability (24 h, classic 24 h Holter ECG), ambulatory BP monitoring, HR turbulence, baroreflex sensitivity, muscle sympathetic nerve activity, catecholamine assessment and cardiovascular sympathetic tests, heart sympathetic imaging. Although it is common complication, the significance of CAN has not been fully appreciated and there are no unified treatment algorithms for today. Treatment is based on early diagnosis, life style changes, optimization of glycemic control and management of cardiovascular risk factors. Pathogenetic treatment of CAN includes: Balanced diet and physical activity; optimization of glycemic control; treatment of DLP; antioxidants, first of all α-lipoic acid (ALA), aldose reductase inhibitors, acetyl-L-carnitine; vitamins, first of all fat-soluble vitamin B1; correction of vascular endothelial dysfunction; prevention and treatment of thrombosis; in severe cases-treatment of OH. The promising methods include prescription of prostacyclin analogues, thromboxane A2 blockers and drugs that contribute into strengthening and/or normalization of Na⁺, K⁺-ATPase (phosphodiesterase inhibitor), ALA, dihomo-γ-linolenic acid (DGLA), ω-3 polyunsaturated fatty acids (ω-3 PUFAs), and the simultaneous prescription of ALA, ω-3 PUFAs and DGLA, but the future investigations are needed. Development of OH is associated with severe or advanced CAN and prescription of nonpharmacological and pharmacological, in the foreground midodrine and fludrocortisone acetate, treatment methods are necessary.

Early commitment of cardiovascular autonomic modulation in Brazilian patients with congenital generalized lipodystrophy

BACKGROUND

Metabolic abnormalities in congenital generalized lipodystrophy (CGL) are associated with microvascular complications. However, the evaluation of different types of neuropathy in these patients, including the commitment of cardiovascular autonomic modulation, is scarce. The objective of the present study was to determine the prevalence of cardiovascular autonomic neuropathy (CAN) in patients with CGL compared with individuals with type 1 diabetes and healthy subjects.

METHODS

Ten patients with CGL, 20 patients with type 1 diabetes and 20 healthy subjects were included in the study. Controls were paired 1:2 for age, gender, BMI and pubertal stage. Heart rate variability (HRV) was analyzed using cardiovascular autonomic reflex tests, including postural hypotension test, Valsalva (VAL), respiratory (E/I) and orthostatic (30/15) coefficients, and spectral analysis of the HRV, determining very low (VLF), low (LF) and high (HF) frequencies components. The diagnosis of CAN was defined as the presence of at least two altered tests.

RESULTS

CAN was detected in 40% of the CGL patients, 5% in type 1 diabetes patients and was absent in healthy individuals (p < 0.05). We observed a significant reduction in the E/I, VLF, LF and HF in CGL cases vs. type 1 diabetes and healthy individuals and lower levels of 30/15 and VAL in CGL vs. healthy individuals. A significant positive correlation was observed between leptin and 30/15 coefficient (r = 0.396; p = 0.036) after adjusting for insulin resistance and triglycerides. Autonomic cardiovascular tests were associated with HbA1c, HOMA-IR, triglycerides and albumin/creatinine ratio in CGL cases.

CONCLUSIONS

We observed a high prevalence of CAN in young patients with CGL, suggesting that insulin resistance, hypertriglyceridemia and hypoleptinemia, may have been involved in early CAN development. Additional studies are needed to evaluate the role of leptinemia in the physiopathogenesis of the condition.

Neuropathy-specific alterations in a Mexican population of diabetic patients

Background

Neuropathy is one of the major complications of type 2 diabetes mellitus. Our first aim was to determine the clinical characteristics of a population of diabetic patients with different types of neuropathy. Our next goal was to characterize the cytokine profile (IL-6 and IL-10), nerve growth factor (NGF) and circulating cell-adhesion molecules in these patients. Finally, we aimed to compare the renal function among the groups of neuropathic patients.

Methods

In a cross-sectional study, we included 217 diabetic patients classified in three groups: sensory polyneuropathy with hypoesthesia (DS_hP) or hyperesthesia (DS_HP), and motor neuropathy (DMN). Two control groups were included: one of 26 diabetic non-neuropathic patients (DNN), and the other of 375 non-diabetic (ND) healthy subjects. The participants were attending to the Mexican Institute of Social Security.

Results

The circulating levels of NGF were significantly lower in diabetic patients, compared to healthy subjects. The range of IL-6 and IL-10 levels in neuropathic patients was higher than the control groups; however, several samples yielded null measurements. Neuropathic patients also showed increased circulating levels of the adhesion molecules ICAM, VCAM, and E-Selectin, compared to the ND group. Moreover, neuropathic patients showed reduced glomerular filtration rates compared to healthy subjects (82–103 ml/min per 1.73 m², data as range from 25th–75th percentiles), especially in the group with DMN (45–76 ml/min per 1.73 m²).

Conclusions

Some particular alterations in neuropathic patients included -but were not limited to- changes in circulating NGF, cell adhesion molecules, inflammation, and the worsening of the renal function. This study supports the need for further clinical surveillance and interventions considering a neuropathy-related basis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-017-0939-6) contains supplementary material, which is available to authorized users.

Nkx2.5 is essential to establish normal heart rate variability in the zebrafish embryo

Heart rate variability (HRV) has become an important clinical marker of cardiovascular health and a research measure for the study of the cardiac conduction system and its autonomic controls. While the zebrafish (Danio rerio) is an ideal vertebrate model for understanding heart development, HRV has only recently been investigated in this system. We have previously demonstrated that nkx2.5 and nkx2.7, two homologues of Nkx2-5 expressed in zebrafish cardiomyocytes, play vital roles in maintaining cardiac chamber-specific characteristics. Given observed defects in ventricular and atrial chamber identities in nkx2.5^-/- embryos coupled with conduction system abnormalities in murine models of Nkx2.5 insufficiency, we postulated that reduced HRV would serve as a marker of poor cardiac health in nkx2.5 mutants and in other zebrafish models of human congenital heart disease. Using live video image acquisition, we derived beat-to-beat intervals to compare HRV in wild-type and nkx2.5^-/- embryos. Our data illustrate that the nkx2.5 loss-of-function model exhibits increased heart rate and decreased HRV when compared with wild type during embryogenesis. These findings validate HRV analysis as a useful quantitative tool for assessment of cardiac health in zebrafish and underscore the importance of nkx2.5 in maintaining normal heart rate and HRV during early conduction system development.

Association between severity of hypoglycemia and loss of heart rate variability in patients with type 1 diabetes mellitus

BACKGROUND

The occurrence of hypoglycemia has been associated with the presence of cardiovascular autonomic neuropathy. Cardiovascular autonomic reflex tests are the gold standard diagnostic method for cardiovascular autonomic neuropathy. Nevertheless, impaired heart rate variability indices on spectral analysis have been reported before cardiovascular autonomic reflex test abnormalities arise. The objective of the present study was to analyse the association between the severity of hypoglycemia and indices of heart rate variability on spectral analysis.

METHODS

Consecutive type 1 diabetes patients were prospectively enrolled. Heart rate variability indices were assessed by spectral analysis. One abnormal test result was used to define impaired spectral analysis. The severity of hypoglycemia was evaluated by a hypoglycemia score and patients were classified into absent/minor or moderate/severe hypoglycemia groups.

RESULTS

Patients with moderate/severe hypoglycemia were older, had longer duration of diabetes and had higher rates of diabetic complications. After adjusting for baseline clinical characteristics, impaired spectral analysis (OR: 3.85; 95% IC 1.23 - 12.02; p = 0.020), nephropathy (OR: 4.15, 95% IC 1.27 - 13.54; p = 0.018) and macrovascular complications (OR: 12.18, 95% IC 1.14 - 129.84; p = 0.038) remained independent predictors of moderate/severe hypoglycemia. Patients with moderate/severe hypoglycemia had lower heart rate variability in the high frequency band of spectral analysis, reflecting a decreased parasympathetic tonus on the heart. These patients also had higher low frequency/high frequency ratios, ultimately denoting the occurrence of cardiovascular autonomic imbalance.

CONCLUSIONS

Impaired heart rate variability on spectral analysis, nephropathy and macrovascular complication were shown to independently predict moderate/severe hypoglycemia. Patients with moderate/severe hypoglycemia showed loss of the cardio protective effect of vagal activity according to spectral analysis. Copyright © 2016 John Wiley & Sons, Ltd.

Association between obesity and heart rate variability indices: an intuition toward cardiac autonomic alteration - a risk of CVD

BACKGROUND

Obese people have a higher prevalence of cardiovascular disease, which is supposed to be due to autonomic dysfunction and/or metabolic disorder. The alterations in cardiac autonomic functions bring out the changes in the heart rate variability (HRV) indicators, an assessing tool for cardiac autonomic conditions.

OBJECTIVE

To compare the cardiac autonomic activity between obese and normal weight adults and find out the highest association between the indices of HRV and obesity.

METHODS

The study was conducted in 30 adult obese persons (body mass index [BMI] >30 kg/m²) and 29 healthy normal weight controls (BMI 18-24 kg/m²). Short-term HRV variables were assessed using standard protocol. Data were compared between groups using Mann-Whitney U test. Obesity indices such as waist circumference, hip circumference, waist-hip ratio (WHR), and BMI were measured and calculated, and they were correlated with HRV indices using Spearman's correlation analysis.

RESULTS

In the obese group, there was a significant increase in the mean heart rate, whereas the HRV parasympathetic indicators were less (eg, root mean square of differences of successive RR intervals [28.75 {16.72-38.35} vs 41.55 {30.6-56.75} ms, p=0.018], number of RR intervals that differ by >50 ms, that is, NN50 [15.5 {2-39} vs 83.5 {32.75-116.25}, p=0.010], etc) and the sympathetic indicator low frequency (LF)/high frequency (HF) ratio (1.2 [0.65-2.20] vs 0.79 [0.5-1.02], p=0.045) was more than that of the normal weight group. Spearman's correlation between HRV and obesity indices showed significant positive correlation of WHR with LF in normalized unit (r=0.478, p<0.01) and LF/HF ratio (r=0.479, p<0.01), whereas it had significant negative correlation with high frequency power ms² (r=-0.374, p<0.05) and HF in normalized unit (r=-0.478, p<0.01). There was a nonsignificant correlation of BMI with HRV variables in obese individuals.

CONCLUSION

Increased WHR, by far an indicator of visceral adiposity, was strongly associated with reduced cardiac parasympathetic and increased sympathetic activity in obese individuals defined by BMI. However, BMI itself has a weak relationship with HRV cardiac autonomic markers. Thus, even with a slight increase in WHR in an individual, there could be a greater risk of cardiovascular morbidity and mortality brought about by cardiac autonomic alterations.

Cardiac Involvement in Peripheral Neuropathies

Cardiac autonomic neuropathy (CAN) is the least recognized and understood complication of peripheral neuropathy. However, because of its potential adverse effects including sudden death, CAN is one of the most important forms of autonomic neuropathies. CAN presents with different clinical manifestations including postural hypotension, exercise intolerance, fluctuation of blood pressure and heart rate, arrhythmia, and increased risk of myocardial infarction. In this article, the prevalence, clinical presentations, and management of cardiac involvement in certain peripheral neuropathies, including diabetic neuropathy, Guillain-Barré syndrome, chronic inflammatory polyneuropathy, human immunodeficiency virus-associated neuropathy, hereditary neuropathies, and amyloid neuropathy are examined in detail.

A cross-sectional assessment to detect type 2 diabetes with endothelial and autonomic nervous system markers using a novel system

Background

Type 2 diabetes mellitus is frequently unrecognized until complications appear. Diabetic autonomic neuropathy is one of the early complications of type 2 diabetes mellitus, resulting in autonomic nervous system (ANS) dysfunction. The purpose of this study was to determine the validity of ANS function indicators to screen for type 2 diabetes mellitus, as measured by the TM-Oxi and SudoPath system.

Methods

All enrolled participants completed a basic sociodemographic and medical history questionnaire including current medications. Healthy controls (n = 25) underwent a 2-hour oral glucose tolerance test (OGTT) to evaluate glucose, insulin, and insulin C-peptide. Patients with type 2 diabetes mellitus (n = 24) were assessed with fasting plasma glucose (FPG) and glycosylated hemoglobin. The TM-Oxi and SudoPath system evaluation was completed by all subjects. Data were analyzed using SPSS 22. Frequency and descriptive statistics were calculated on all variables. The criterion for statistical significance was α = 0.05.

Results

The twenty-five healthy controls had a mean age of 37.0 years. The twenty-four type 2 diabetes mellitus patients currently undergoing standard treatment had a mean age of 48.9 years. Based on the American Diabetes Association guidelines, we detected pre-diabetes in 4 subjects and diabetes in 1 subject, while all other subjects had normal FPG values. At 120 minutes, the correlations between the OGTT and cardiometabolic risk score (CMRS) were: r = 0.56 (p = 0.004) for glucose and r = 0.53 (p = 0.006) for insulin. At 120 minutes, the correlations between the OGTT and photoplethysmography index (PTGi) were: r = -0.56 (p = 0.003) for glucose and r = -0.41 (p = 0.04) for insulin. The CMRS, PTGi, and plethysmography total power index (PTGVLFi) differed significantly between the diabetes patients and healthy participants. The specificity and sensitivity for the CMRS, PTGi, and PTVLFi comparing the diabetes patients with healthy controls were high.

Conclusion

The TM-Oxi and SudoPath system shows promise as a valid, convenient, and non-invasive screening method for type 2 diabetes mellitus. The ANS function and CMR indicators measured by this system may be useful in guiding diabetes and cardiovascular health screening, treatment, and monitoring.

Leptin, adiponectin, and heart rate variability among police officers

OBJECTIVES

Police officers have a high prevalence of cardiovascular disease (CVD). Reduced heart rate variability (HRV) is known to increase CVD risk. Leptin and adiponectin may be related to CVD health. Therefore, our objective was to investigate the relationship between these variables and HRV.

METHODS

Leptin and adiponectin levels were measured in 388 officers from the Buffalo Cardio-Metabolic Occupational Police Stress study. HRV was assessed according to methods published by the Task Force of the European Society of Cardiology and the North American Society of Pacing Electrophysiology for measurement and analysis of HRV. Mean values of high-frequency (HF) and low-frequency (LF) HRV were compared across tertiles of leptin and adiponectin using analysis of variance and analysis of covariance; trends were assessed using linear regression models.

RESULTS

Leptin, but not adiponectin, was significantly and inversely associated with HRV. Body mass index (BMI) and percent body fat significantly modified the association between leptin and LF (but not HF) HRV. Among officers with BMI < 25 kg/m(2) , leptin was not significantly associated with HRV. However, among officers with BMI ≥ 25 kg/m(2) , leptin was inversely associated with HRV, after adjustment for age, gender, and race/ethnicity; HF HRV, P = 0.019 and LF HRV, P < 0.0001. Similarly, among officers with percent body fat ≥ 25.5%, leptin and LF HRV showed significant, inverse associations (adjusted P = 0.001).

CONCLUSIONS

Leptin levels were inversely associated with LF HRV, especially among officers with increased adiposity. Increased leptin levels may be associated with CVD-related health problems.

Cardiovascular autonomic neuropathy contributes to sleep apnea in young and lean type 1 diabetes mellitus patients

Knowledge about association between sleep apnea and cardiovascular autonomic neuropathy (CAN) in type 1 diabetes mellitus (T1DM) might give some insight into the pathogenesis of this condition in these patients. In obese patients, excessive central adiposity, including a large neck circumference, can contribute to obstructive sleep apnea (OSA). Its presence in non-obese patients, however, indicates that it could be correlated with autonomic neuropathy. The aim of this study was to compare the prevalence of OSA in young and lean T1DM patients with and without CAN. We studied 20 adult, non-obese, T1DM patients who were divided into two groups according to the results of the cardiovascular autonomic reflex tests (CARTs). These two groups (9 with CAN and 11 without CAN) were compared to a control group of 22 healthy individuals, who were matched by age and BMI. A polysomnography was performed and sleep was analyzed. The CAN+ group had a significantly higher prevalence of sleep apnea compared to the other groups (67% CAN+; 23% CAN-; 4.5% controls: CAN+ vs. Control; p = 0.006 and CAN+ vs. CAN-; p = 0.02). The CAN- group had higher sleep efficiency compared to the CAN+ group, demonstrating impaired sleep architecture in diabetics with this chronic complication. In conclusion, OSA may be related to the presence of CAN in young and lean T1DM patients. It could contribute to worse the prognosis and reducing the quality of life of these patients without specific treatment of these conditions.

Predictors of cardiovascular autonomic neuropathy in patients with type 1 diabetes

Cardiovascular disease (CVD) is the leading cause of mortality in patients with type 1 diabetes (T1D). The cardiovascular autonomic neuropathy (CAN), although considered as an independent risk factor for CVD, remains underdiagnosed. The aim of this paper was to determine the prevalence, predictors of CAN in patients with T1D and its association with other chronic complications of diabetes. Patients with T1D underwent a clinical-epidemiological survey, had blood and urinary samples collected, performed ophthalmoscopic and clinical neurological examination and cardiovascular reflex tests. One hundred and fifty one patients with T1D, 53.6% female, 45.7% Caucasian, mean age of 33.4 ± 13 years, diabetes duration of 16.3 ± 9.5 years, and glycated hemoglobin levels of 9.1 ± 2% were evaluated. The prevalence of CAN in the studied population was 30.5%. CAN was associated with age (p = 0.01), diabetes duration (p = 0.036), hypertension (p = 0.001), resting heart rate (HR) (p = 0.000), HbA1c (p = 0.048), urea (p = 0.000), creatinine (p = 0.008), glomerular filtration rate (p = 0.000), urinary albumin concentration (p = 0.000), LDL (p = 0.048), free T4 (p = 0.023), hemoglobin (p = 0.01) and presence of retinopathy (p = 0.000), nephropathy (p = 0.000) and diabetic neuropathy (p = 0.000), the following symptoms syncope (p = 0.000), post prandial nausea (p = 0.042), early satiety (p = 0.031), sexual dysfunction (p = 0.049), and gustatory sweating (p = 0.018). In logistic regression model, it was observed that only resting HR, diabetic neuropathy, and retinopathy were independent associated with CAN. In conclusion, CAN is a common chronic complication of T1D affecting about 30% of the studied population and is associated with the presence of other chronic complications. Indicators of CAN included age, diabetes duration, hypertension, resting HR, diabetic neuropathy and retinopathy, and symptoms suggestive of autonomic neuropathy. This study confirms the importance of systematic and early screening for CAN.