Baseline heart rate variability in children and adolescents with vasovagal syncope

Abstract

PurposeThis study aimed to evaluate the autonomic imbalance in syncope by comparing the baseline heart rate variability (HRV) between healthy children and those with vasovagal syncope.MethodsTo characterize the autonomic profile in children experiencing vasovagal syncope, we evaluated the HRV of 23 patients aged 7-18 years and 20 healthy children. These children were divided into preadolescent (<12 years) and adolescent groups. The following time-domain indices were calculated: root mean square of the successive differences (RMSSD); standard deviation of all average R-R intervals (SDNN); and frequency domain indices including high frequency (HF), low frequency (LF), normalized high frequency, normalized low frequency, and low frequency to high frequency ratio (LF/HF).ResultsHRV values were significantly different between healthy children and those with syncope. Student t test indicated significantly higher SNDD values (60.46 ms vs. 37.42 ms, P=0.003) and RMSSD (57.90 ms vs. 26.92 ms, P=0.000) in the patient group than in the control group. In the patient group, RMSSD (80.41 ms vs. 45.89 ms, P=0.015) and normalized HF (61.18 ms vs. 43.19 ms, P=0.022) were significantly higher in adolescents, whereas normalized LF (38.81 ms vs. 56.76 ms, P=0.022) and LF/HF ratio (0.76 vs. 1.89, P=0.041) were significantly lower in adolescents. In contrast, the control group did not have significant differences in HRV values between adolescents and preadolescents.ConclusionThe results of this study indicated that children with syncope had a decreased sympathetic tone and increased vagal tone compared to healthy children. Additionally, more severe autonomic imbalances possibly occur in adolescents than in preadolescents.

Cardiac nodal and cardiac autonomic functions in children with vasovagal syncope

“…There are studies evaluating sympathovagal balance in children suffering from syncope by investigating the parameters of heart rate variability (HRV). However, these studies have yielded controversial results [6][7][8][9][10] . D y s f u n c t i o n o f s i n o a t r i a l n o d e a n d atrioventricular node is another rare cause of syncope 3 .…”

Baroreflex Sensitivity Predicts Response to Metoprolol in Children With Vasovagal Syncope: A Pilot Study

“…Some studies showed that the sympathetic nervous system was over-activated in some VVS patients in a supine position (Sehra et al, 1999;Alehan et al, 2002;Tao et al, 2019c). In such a position, excessive sympathetic tone could be compensated for by activating the parasympathetic nervous system to restore a stable hemodynamic condition (Shim et al, 2014). Nonetheless, during standing, physiological adjustment lowers the parasympathetic activity, and the overstimulation of the sympathetic nervous system contracts the ventricular muscle with an "empty chamber."…”

Effects of motor skills training program on the cardiac autonomic control in children with developmental coordination disorder: a preliminary study

“…Furthermore, the intervention decreased overall HRV and cardiac parasympathetic modulation, which was unexpected, since decreased HRV has been associated with increased risk for cardiovascular events [8,16]. On the other hand, decreasing parasympathetic modulation it is of interest in some clinical conditions, such as children with vasovagal syncope [17]. Therefore, this study is a starting point for future studies to address whether children with DCD share a similar autonomic profile with children with vasovagal syncope, which could also contribute to low activity levels commonly seen in DCD children.…”