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Published on: March 21, 2013
QT interval in children with orthostatic dysregulation: Changes in standing load
Miho Sakata1,2, Yoshinobu Oyazato1, Atsushi Nishiyama1
1Department of Pediatrics, Kakogawa Central City Hospital, Kakogawa, Hyogo, Japan.
Background:
The corrected QT interval (QTc) is affected by changes in autonomic sympathovagal modulation. The aim of this study was to determine whether children with orthostatic dysregulation (OD) have a longer QTc while standing than children without OD.
Methods:
We retrospectively assessed patients who underwent the Schellong test and electrocardiography between November 2016 and November 2019. Patients who met the criteria of OD subtypes according to the Japanese clinical guidelines for juvenile OD (version 1) were classified as OD positive (the OD-positive group), and patients who did not meet the criteria were classified as OD negative (the OD-negative group).
Results:
There were 73 patients in the OD-positive group and 52 patients in the OD-negative group. Baseline heart rate, QT interval, and QTc were comparable between the OD-positive and OD-negative groups. Heart rate after standing was significantly higher in the OD-positive group than in the OD-negative group (median: 33 bpm vs. 21 bpm, p < 0.001). Further, shortening of QT interval after standing was greater in the OD-positive group than in the OD-negative group (median: 19 ms vs. 8 ms, p = 0.015). The QTc significantly increased from baseline to standing in both groups. Changes in the QT interval corrected by Bazett's formula were greater in the OD-positive group than in the OD-negative group (median: 73 ms vs. 42 ms, p < 0.001).
Conclusions:
The QTc increased significantly from baseline to standing in the OD-positive group. Thus, a high QTc while standing could be considered an auxiliary marker for OD diagnosis.
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