Interplay between baroreflex sensitivity, obesity and related cardiometabolic risk factors (Review)

The predictive role of autonomic neuropathy in pre- and post-liver transplantation outcomes: a systematic review and meta-analysis

Background

Autonomic neuropathy (AN) in cirrhotic patients has been linked to a higher risk of cirrhosis-related complications and worse outcomes before, during or after liver transplantation (LT). However, only a few studies exist with inconsistent results.

Methods

We searched for all articles published until September 2023 that described a diagnosis of AN based on cardiovascular autonomic reflex tests (CARTs), assessment of the rate-corrected QT interval (QTc), heart rate variability (HRV), and baroreflex sensitivity (BRS) tests, in order to evaluate the predictive role of AN in cirrhosis and/or peri-/post-LT prognosis.

Results

Twenty-five studies were included: 5, 12, 9, and 1 study, respectively, assessed the predictive role of CARTs, prolonged QTc, HRV indices, and BRS in cirrhosis or peri-/post-LT prognosis. In CARTs-based analysis, the pre-LT pooled mortality rate was significantly higher in cirrhotics with AN compared to those without AN (20% vs. 6%; P=0.01). However, no difference was found between patients with and without pre-LT prolonged QTc in the pre-LT pooled mortality rates (41% vs. 18%; P=0.08), pooled peri-transplant risk of major complications (29% vs. 17%; P=0.08) or post-LT pooled mortality rates (15% vs. 12%; P=0.36). In HRV-based analysis, the standard deviation of normal-to-normal intervals was significantly lower in non-survivors, compared to survivors with cirrhosis: standardized mean difference -2.59, 95% confidence interval -4.75 to -0.43; P=0.04.

Conclusions

The presence of CARTs- and HRV-based AN was a good predictor of mortality in the pre-LT setting. Preoperative prolonged QTc did not seem to be associated with the outcome before or after LT.

Dynamic vagal-mediated connectivity of cortical and subcortical central autonomic hubs predicts chronotropic response to submaximal exercise in healthy adults

BACKGROUND

Despite accumulation of a substantial body of literature supporting the role of exercise on frontal lobe functioning, relatively less is understood of the interconnectivity of ventromedial prefrontal cortical (vmPFC) regions that underpin cardio-autonomic regulation predict cardiac chronotropic competence (CC) in response to sub-maximal exercise.

METHODS

Eligibility of 161 adults (mean age = 48.6, SD = 18.3, 68% female) was based upon completion of resting state brain scan and sub-maximal bike test. Sliding window analysis of the resting state signal was conducted over 45-s windows, with 50% overlap, to assess how changes in photoplethysmography-derived HRV relate to vmPFC functional connectivity with the whole brain. CC was assessed based upon heart rate (HR) changes during submaximal exercise (HR change /HRmax (206-0.88 × age) - HRrest).

RESULTS

During states of elevated HRV the vmPFC showed greater rsFC with an 83-voxel region of the hypothalamus (p < 0.001, uncorrected). Beta estimates of vmPFC connectivity extracted from a 6-mm sphere around this region emerged as the strongest predictor of CC (b = 0.283, p <.001) than age, BMI, and resting HRV F(8,144) = 6.30, p <.001.

CONCLUSION

Extensive glutamatergic innervation of the hypothalamus by the vmPFC allows for top-down control of the hypothalamus and its various autonomic efferents which facilitate chronotropic response during sub-maximal exercise.

Predictors of Cardiac Autonomic Dysfunction in Obesity-Related Hypertension

INTRODUCTION

Cardiac Autonomic Dysfunction (CAD) is an overlooked cardiovascular risk factor in individuals with obesity-related hypertension. Despite its clinical significance, there is a notable lack of clarity regarding the pathophysiological correlates involved in its onset and progression.

AIM

The present study aimed to identify potential predictors of CAD in obesity-related hypertension.

METHODS

A total of 72 participants (34 men and 38 women) were enrolled. Comprehensive evaluations were conducted, including cardiac autonomic function assessments, body composition estimation and biochemical analysis. Participants were categorized as CAD-positive or CAD-negative based on Ewing's criteria for autonomic dysfunction. Univariate logistic regression analysis was performed to identify potential predictors for CAD. Multivariate logistic regression models were further constructed by adjusting clinically relevant covariates to identify independent predictors of CAD.

RESULTS

Multivariate logistic regression analysis revealed that resting heart rate (HRrest), (odds ratio, confidence interval: 0.85, 0.78-0.93; p = 0.001) and percentage body fat (BF%), (odds ratio, confidence interval: 0.78, 0.64-0.96; p = 0.018) were significant independent predictors of CAD. Receiver Operating Characteristic curve analysis depicted optimal cut-off values for HRrest and BF% as > 74.1 bpm and > 33.6%, respectively. Multicolinearity analysis showed variance inflation factors (VIF) below the cautionary threshold of 3.

CONCLUSIONS

The HRrest and BF% emerged as significant independent predictors of CAD in obesity-related hypertension. Therapeutic strategies should target HRrest < 74.1 bpm and BF% < 33.6% to mitigate CAD risk in this population. Future trials are required to establish causal relationships and may consider additional confounding variables in obesity-related hypertension.

Cardiovascular autonomic nervous function in children conceived by assisted reproductive technology with frozen or fresh embryo transfer

As a result of epigenetic changes, children conceived by assisted reproduction may be at risk of premature cardiovascular aging with notably increased blood pressures. Their cardiovascular autonomic nervous function is unknown. Therefore, this study investigated the cardiovascular autonomic nervous function in 8-12-yr-old children (51% girls) conceived naturally (n = 33) or by assisted reproduction with frozen (n = 34) or fresh (n = 38) embryo transfer by evaluating heart rate variability, during rest; from provocation maneuvers; and from baroreflex function. Heart rate and blood pressure response to provocation maneuvers and baroreflex function were comparable between children conceived naturally or by assisted reproduction. The mean RR-interval and high-frequency component of heart rate variability were lower in children conceived by assisted reproduction than in children conceived naturally. Children conceived by fresh embryo transfer had ∼17% lower heart rate-corrected standard deviation of normal-to-normal R-R intervals; ∼22% lower heart rate-corrected square root of the mean of the squared difference between successive R-R intervals; and ∼37% higher low-frequency/high-frequency ratio than naturally conceived children. Children conceived by assisted reproduction still had lower heart rate variability and vagal modulation than naturally conceived children after adjustment for confounders. Thus, these results raise the possibility of sympathetic predominance in children conceived by assisted reproduction. Therefore, it is important to reproduce these results in larger and older cohorts as sympathetic predominance relates with cardiovascular and metabolic diseases.NEW & NOTEWORTHY We observed that children conceived by assisted reproductive technology (both frozen and fresh embryo transfer) had lowered heart rate variability during rest as compared with children conceived naturally. During physiological stress maneuvers, however, the cardiovascular autonomic nervous regulation was comparable between children conceived by assisted reproductive technologies and naturally. Our findings highlight the potential that lowered heart rate variability during rest in children conceived by assisted reproductive technologies may precede premature hypertension.

Differences in Heart Rate Variability and Baroreflex Sensitivity between Male and Female Athletes

Heart rate variability (HRV), systolic blood pressure variability (BPV), and spontaneous baroreflex sensitivity (BRS) are indirect and approximate measures of autonomic regulation of the cardiovascular system. Studies have shown differences in HRV and BRS between males and females; however, no study has observed differences in BPV, HRV, or BRS between male and female athletes. One hundred males (age 21.2 ± 2.1 y; BMI 27.4 ± 4.5 kg/m²) and sixty-five females (age: 19.7 ± 1.6 y; BMI 22.7 ± 2.2 kg/m²) were assessed during the pre-season baseline. We collected resting beat-to-beat blood pressure and R-R intervals using finger photoplethysmography and a 3-lead electrocardiogram, respectively. Participants underwent a controlled slow breathing protocol (six breaths/minute: 5 s inhale, 5 s exhale) for 5 min. Spectral and linear analysis was conducted on blood pressure and ECG data. Regression curves were fitted to the blood pressure and R-R signals, with the slopes providing the BRS parameters. Male athletes had significantly (p < 0.05) lower mean heart rate, RR interval SD2/SD1, HRV % low-frequency, and higher BP high-frequency power during controlled respiration. No differences were found in any BRS parameters. HRV and BPV responses to a slow breathing protocol differed between male and female athletes; however, BRS responses did not.

CORRECTION OF AUTONOMIC DYSFUNCTION IN OVERWEIGHT CHILDREN BY NORMALIZING BODY COMPOSITION

OBJECTIVE

The aim: To investigated the effect of a 3-month body weight correction program on the functional state of the ANS in children of primary school age who had an increased body mass index and signs of autonomic dysfunction.

PATIENTS AND METHODS

Materials and methods: 82 children aged 9 to 11 were examined. During 3 months, all examinees underwent a body weight correction course. Body composition was mea¬sured by the bioimpedance method using the body composition analyzer «TANITA-BC-601» (Japan). The functional state of autonomic regulation was assessed using heart rate variability (HRV) indicators obtained by recording standard 5-minute ECG intervals using the computer hardware and software complex "CARDIOLAB" (XAI-MEDICA, Ukraine).

RESULTS

Results: Statistical processing of HRV indicators showed that 51 children (62.2%) had signs of autonomic dysfunction. In the first group, there was a statistically significant decrease in body weight (from 47.33±4.62 to 44.12±3.96), BMI (from 28.15±2.64 to 26.63±2.87), TFC (from 33.54±3.68 to 30.89±2.81), VF (from 7.056±1.814 to 4.817±2.017) with a simultaneous statistically probable increase in the FFM index (from 60.27±2.47 to 63.15±2,38). According to the time domain indicators of HRV, children in first group have increased the TP of autonomous heart rhythm regulation, as indicated by a statistically significant increase in SDNN from 38.43±6.39 ms to 51.65±7.19 ms (р<0.05); the activity of the sympathetic link of the ANS decreased according to AMo from 41.23±6.17% to 34.29±5.83% (р<0.05) and the intensity of autonomic regulation according to IS, which decreased from 116.3±31,6 units to 81.2±29.1 units (p<0.05).

CONCLUSION

Conclusions: 3-month body weight correction program led to the elimination of signs of autonomic dysfunction in 43.9% of the examined persons.