All issues > Volume 44(4); 2001

Original Article

J Korean Pediatr Soc. 2001;44(4):418-425. Published online April 15, 2001.

Ventricular Inhomogeneity and Beat-to-beat QT Interval Variability after Surgical Repair of Tetralogy of Fallot

Su-Hyun SH Kim¹, Myung-Kul MK Yum¹, Nam-Su NS Kim¹, Chang-Ryul CR Kim¹, Chul-Burm CB Lee², Chung-Ill CI Noh³, Hee-Soo HS Kim⁴

¹Department of Pediatrics, Hanyang University Kuri Hospital, Korea
²Department of Thoracic Surgery, Hanyang University Kuri Hospital,
³Department of Pediatrics, Seoul University Hospital, Korea
⁴Department of Anesthesiology, Seoul University Hospital, Korea

Correspondence Myung-Kul MK Yum ,Email: mkyumm@email.hanyang.ac.kr

Abstract

Purpose
: The object of this study is to determine whether QT interval variability in patients with postoperative tetralogy of Fallot increases.
Methods
: We enrolled 41 patients who had total correction of tetralogy of Fallot, and 31 healthy controls. They were 6-12 years old. Patients were divided into 2 groups : arrhythmia-positive patients(n=10) who had ventricular premature contractions more than 30/hour or who had couplets, and arrhythmia-negative patients(n=31). We selected the 10-minute arrhythmia-free portion of 24-hour ambulatory ECG recorded during sleep(1-3AM). We selected the 2nd beat of recordings for a template, then found the QT interval for each beat. The method was that T-wave shape best matches template T-wave under the time-stretch model. The mean heart rate and variance and mean QT interval and variance were computed and then a QT variability index(QTVI)-which represents the log ratio between QT interval variability and heart rate variability-was derived.
Results
: Postoperative tetralogy of Fallot patients with/without ventricular arrhythmia showed significantly increased QTVI compared with the control(-0.481¡¾0.310/-0.661¡¾0.376 vs -1.200¡¾0.380, P<0.0001). There was a trend that QTVI in patients with ventricular arrhythmia increased more than in patients without ventricular arrhythmia, but there were no statistical significances.
Conclusion
: QT interval variability increased in repaired tetralogy of Fallot patients with/without ventricular arrhythmia compared with the control. And this finding indicates that inhomogeneity of temporal ventricular repolarization exists in repaired tetralogy of Fallot patients.

Keywords :Tetralogy of fallot, Ventricular arrhythmia, Temporal ventricular repolarization inhomogeneity, QT variability index