Clinical significance of changes in T wave and ST segment amplitudes on electrocardiogram from supine to standing position among children with unexplained chest tightness or pain in resting stage

Objective To investigate the clinical significance of changes in T wave and ST segment amplitudes on electrocardiogram(ECG) from supine to standing position in children with unexplained chest tightness or pain in resting stage.Methods A total of 122 6-14-year-old children with a chief complaint of unexplained chest tightness or pain(resting stage) underwent head-up tilt test(HUTT).According to HUTT results,these children were divided into HUTTpositive(n=61) and HUTT-negative groups(n=61).They underwent 12-lead ECG in the supine and standing positions,and heart rate and T wave and ST segment amplitudes in II,III,aVF and V5 leads were measured.Results In the HUTT-negative group,heart rates were significantly higher in the standing position than in the supine position(P0.05),T wave amplitudes in II,III,aVF,and V5 leads were significantly lower in the standing position than in the supine position(P0.05),and ST segment amplitudes in II,aVF and V5 leads were significantly higher in the standing position than in the supine position(P0.05).In the HUTT-positive group,heart rates were significantly higher in the standing position than in the supine position(P0.05),T wave amplitudes in II,III,aVF and V5 leads were significantly lower in the standing position than in the supine position(P0.05),and ST segment amplitude in V5 lead was significantly higher in the standing position than in the supine position(P0.05).There were no significant differences between the two groups with respect to ST segment amplitude and T wave amplitude in II,III and aVF leads of the supine or standing position(P0.05).Compared with the HUTT-negative group,the HUTT-positive group had significantly greater T wave amplitude differences in II,III,aVF and V5 leads,and heart rate difference from supine to standing position(P0.05).Conclusions Among the children with unexplained chest tightness or pain in resting stage,T wave amplitude differences in II,III,aVF and V5 leads and heart rate difference from supine to standing position are greater in the HUTT-positive group than in the HUTT-negative group.This suggests that the changes in T wave amplitude on ECG from supine to standing position can indicate autonomic nervous system dysfunction.