Cardiac Autonomic Modulation of Children with Down Syndrome

Abstract

The aim of this study is to analyze the autonomic modulation in children with Down syndrome (DS). The study was conducted with a convenience sample of children with DS and without heart disease, from the Genetics Clinic of the Hospital Infantil Darcy Vargas and APAE São Paulo, São Paulo, SP, Brazil. The control group was matched for sex and age. The analysis of autonomic modulation was performed using the indices of heart rate variability (HRV). The children remained in the supine position with spontaneous breathing for 20 min. Heart rate was recorded beat-to-beat. HRV analysis was performed in time and frequency domain. For data analysis, we used Student's t test: unpaired and Mann-Whitney. It was considered statistically significant at p < 0.05. From 75 children with DS, 50 were excluded, a total of 25 children [16 boys, 8.6 (1.4) years] participated in this study, and the control group also consisted of 25 children [16 boys, 9.0 (1.2) years] without the syndrome. The BMI of the volunteers with DS was higher than the controls [19.1 (2.9) vs. 15.8 (1.2), p < 0.0001]. There were differences between groups in the indices in frequency domain: LFms(2) [1242.1 (788.25) vs. 786.44 (481.90), p = 0.040], LFun [69.104 (11.247) vs. 57.348 (11.683), p = 0.0004], HFun [30.896 (11.247) vs. 42.520 (11.634), p = 0.0004] and LF/HF [2.594 (1.104) vs. 1.579 (0.9982), p = 0.0004]. No differences were observed in time domain indices. The results indicate increased indices representing the sympathetic branch of the autonomic nervous system and those that indicate the overall modulation in children with DS.

Heart rate variability in individuals with Down syndrome – A systematic review and meta-analysis

“…Although some researchers suggest that the problem is the parasympathetic decrease (Giagkoudaki et al, 2010;Mendonça et al, 2013), for others the dysfunction is sympathetic hyperactivity. For Carvalho et al (2015), even though the individuals with DS respond physiologically to autonomic tasks, such responses are lower than that of controls, which could be explained by sympathetic predominance of these individuals, which hinder or delay the action of the vagus front of excitatory tasks (Carvalho et al, 2015).…”

“…Isolated rest condition was evaluated in only one study (Carvalho et al, 2015), whose results indicated increasing indices representing the sympathetic branch of the ANS and those that indicate the overall modulation in children with DS.…”

“…As we have revealed, the information about cardiac regulation during the resting state in DS individuals diverges. Independent of their protocol, some studies have found no changes at rest (Iellamo et al, 2005;Figueiroa Figueroa et al, 2005;Angiovlasitis et al, 2011;Mendonça et al, 2013;Bunsawat et al, 2015); others describe an increase in the indices representing the sympathetic branch of the ANS (Carvalho et al, 2015), and others, greater parasympathetic activity at rest (Baynard et al, 2004). Lastly, there are those that indicated reduced total HRV at rest in DS (Giagkoudaki et al, 2010;Goulopoulou et al, 2006), in which there is the decrease in both branches of the ANS.…”

Heart Rate Variability and Cardiopulmonary Dysfunction in Patients with Duchenne Muscular Dystrophy: A Systematic Review

“…Thus, assessment of cardiac electrophysiology could provide patterns of dysfunction that could forecast the course of decline [12]. Accordingly, resting heart rate is a simple measurement with important prognostic implications [13,14]. In addition, HRV provides a well-characterized, non-invasive means to quantitatively and indirectly assess the autonomic nervous system (ANS) that controls cardiac physiology.…”

Hormonal and autonomic responses to autonomic stimulation are altered in young men with Down syndrome

“…Specifically, these characteristics include hypotonia, short stature, overweight, endocrine disorders and dysautonomia [2,3]. The autonomic dysfunction in this population could be associated with increased morbidity and mortality [4,5]. It has been shown that subjects with DS have a blunted cardiovascular response to exercise or autonomic stimulation including chronotropic incompetence, reduced heart rate and blood pressure [6][7][8][9].…”