Heart Rate Variability in Adults with Sickle Cell Anemia During a Multitasking Field Test

Background: The integrity of the autonomic nervous system (ANS) is essential for keeping physiological processes stable, even under stress. Since there is growing interest in heart rate variability (HRV) analysis for the noninvasive assessment of the ANS in sickle cell anemia (SCA) patients, we studied the behavior of the ANS in the presence of a stressor that simulates daily-life multitasking, the Glittre ADL test (GA-T). Objectives: To evaluate the involvement of the ANS using HRV in adults with SCA during the GA-T and to quantify the strength of the correlation of HRV with lung and muscle functions. Methods: In this cross-sectional study, 16 adults with SCA and 12 healthy controls without sickle cell disease underwent HRV assessment during the GA-T, pulmonary function tests (spirometry, diffusing capacity for carbon monoxide (DLCO), and respiratory muscle testing). Peripheral muscle function [handgrip strength (HGS) and quadriceps strength (QS)] were also measured. Results: Compared to the healthy controls, adults with SCA showed lower HRV, with worse parasympathetic modulation due to reductions in the following indices: the root-mean-square difference of successive normal iRRs (iRR) (RMSSD); the percentage of pairs of consecutive iRRs whose difference is > 50 m (pNN50); the high-frequency component of heart rate variability (HF); and the standard deviation of instantaneous beat-to-beat variability (SD1) (P < 0.001 for all). Compared to healthy controls, individuals with SCA showed greater sympathovagal imbalance (higher ratio between low-frequency and HF components) and lower complexity of the ANS (lower approximate entropy). The GA-T time was correlated with parasympathetic activity indices: RMSSD (rs = -0.650, P < 0.01); pNN50 (rs = -0.932, P < 0.0001), HF (rs = -0.579, P < 0.01), and SD1 (rs = -0.814, P < 0.0001). Correlations between parasympathetic activity indices and DLCO, HGS, and QS measures were also significant. Conclusions: Adults with SCA have low HRV, with low parasympathetic activity, sympathovagal imbalance, and abnormal ANS complexity. In addition, lower HRV is associated with longer GA-T time, greater impairment of pulmonary diffusion, and greater muscle strength dysfunction.

Comparative study of heart rate variability in normotensive young adults with family history of hypertension

Background: Hypertension is a risk factor for the development of cardiovascular and cerebro-vascular diseases. Autonomic nervous system plays a crucial role in the development of hypertension. The integrity of autonomic modulation of heart rate is evaluated by analysing heart rate variability (HRV), which refers to oscillations in the intervals between consecutive heartbeats or R-R intervals. The present study was designed to analyse the indices of heart rate variability in the offsprings of hypertensive parents and off springs of normotensive parents to understand if there is any autonomic imbalance between the two groups. Methods: The study was conducted in the Department of Physiology, Government Medical College, Srinagar. The test group consisted of 30 healthy normotensive subjects studying in 1st year of MBBS with hypertensive parents and the control group consisted of healthy normotensive of 1st year of MBBS with both parents normotensive. In time domain analysis the standard deviation of all normal-to-normal intervals {SDNN(ms)} was taken as index of overall HRV. Frequency domain analysis was done with respect to low frequency (LF) analysis and high frequency (HF) analysis. Low and high frequency power were expressed in normalized units.Results: The SDNN was reduced in cases but was not statistically significant. RMSSD was also reduced in cases though not statistically significant. LFnu was found to be significantly higher in cases. The HFnu was significantly reduced in cases. LF/HF ratio was found to be higher in cases and the difference was statistically significant. Conclusions: Our study reveals that incidence of prehypertension and the risk of cardiovascular dysfunction in relation to sympathovagal imbalance is more in the off springs of hypertensive parents than in the off springs of normotensive parents. Sympathovagal imbalance in the form of increased sympathetic drive and decreased parasympathetic drive can lead to prehypertension in these genetically predisposed individuals.

Abstract 13369: Sympathovagal Imbalance Decades After Atrial Septal Defect Repair

Introduction: Heart rate variability (HRV), a measure of the autonomic nervous system activity, is a morbidity and mortality predictor. HRV is decreased in children with atrial septal defects (ASD) indicating parasympathetic withdrawal and sympathetic predominance, and increased right atrial end-diastolic pressure is believed to influence the sympathovagal balance. Despite the belief of a benign long-term outcome after closure, ASD patients have increased mortality rates after the age of 30 yrs. This may correlate to HRV, why we study HRV in adults after closure. Hypothesis: ASD patients have impaired HRV after closure when compared with controls. Methods: Surgically closed ASD patients (n=17, mean age 32±9 yrs., mean time since closure 19±8 yrs.), percutaneously closed ASD patients (n=18, mean age 28±7 yrs., mean time since closure 15±5 yrs.) and age- and gender-matched controls (n=15, mean age 30±9 yrs.) underwent a 48-hr Holter monitoring. Inclusion criteria were an age of minimum 2 yrs. at the time of diagnosis and minimum 3 yrs. must have passed since ASD closure. The following time-domain HRV measures were analyzed: SD of NN intervals (SDNN), SD of the average NN interval for each 5-minute segment, mean of the SDs of all NN intervals for each 5-minute (SDNNi), root mean square of successive RR interval differences (RMSSD), percentage of successive RR intervals that differ by >50 ms (pNN50), and triangular index. Results: Surgically closed ASD patients have an impairment of all time-domain parameters, while transcatheter closed patients have an impairment of half the parameters. Conclusion: These novel findings demonstrate a cardiac sympathovagal imbalance in adult patients several yrs. after ASD closure and may potentially explain why we observe a long-term morbidity and mortality increase in ASD patients.

Relation of Body mass index to Heart rate variability in female medical students

Heart rate variability (HRV) is a simple non-invasive, sensitive measure to evaluate autonomic system activity. Sympathovagal imbalance can explain increased incidence of sudden cardiac deaths associated with increased Body Mass Index (BMI). Understanding the mechanism that connects obesity and autonomic nervous system (ANS) functions is important because increasing obesity prevalence documented among men and women of all ages. The aim of the study is to assess the relationship of body mass index to heart rate variability in young females. In this study, 90 healthy female students, aged between 17-22 years were included. After calculating the BMI, subjects were divided into three groups. HRV was recorded for 5 min using INCO-NIVIQURE DIGITAL ACQUISITION SYSTEM VER.52.0. Low frequency (LF) component, high frequency (HF) component and LF:HF ratio were recorded and the relation between BMI, HF, LF and LF:HF ratio were analysed using ANOVA test. In this study, LF:HF ratio in overweight females was found to be high and parasympathetic was decrease when compared to normal weight and underweight females. Raised BMI is associated with reduced HRV, which correlates with decreased parasympathetic activity and sympathovagal imbalance, thus increases the chances of cardiac autonomic dysfunction and eventually leading to cardiovascular disease in overweight female.

4th A in a triple A syndrome – A rare case report

ObjectivesAAA (Allgrove) syndrome is a rare genetic disorder characterized by cardinal features of adrenal insufficiency, achalasia, and alacrimia.Case presentationA 21 year girl of known case of Triple A syndrome was referred for the evaluation of autonomic function. She was born full term with developmental delay and abnormal gait. Esophageal manometry study by pneumatic balloon dilatation revealed the presence of achalasia cardia. She had signs of peripheral neuropathy and had episodes of fainting and suspected orthostatic hypotension. Cardiovascular autonomic function and heart rate variability tests were conducted as per Ewing protocol, revealed that the patient had sympathovagal imbalance and sympathetic dominance.ConclusionsThe presence of autonomic dysfunction adds the 4th A to the Triple A syndrome (Adrenal insufficiency, Achalasia, Alacrimia and Autonomic dysfunction). Noninvasive autonomic function tests are recommended for Triple A syndrome patients to reduce the morbidity associated with autonomic dysfunction.