All issues > Volume 42(8); 1999

Original Article

J Korean Pediatr Soc. 1999;42(8):1071-1077. Published online August 15, 1999.

Depolarization, Repolarization Inhomogeneity and Late Potential after Surgical Repair of Tetralogy of Fallot

Soo Young SY Kim¹, Myung Chul MC Hyun¹, Sang Bum SB Lee¹, Seung Tae ST Kim², Jong Soo JS Lee³

¹Department of Pediatrics, College of Medicine, Kyung-pook National University, Korea
²Department of Pediatrics, Fatima Hospital, Taegu, Korea
³Department of Pediatrics†, Handong University, Sunlin Hospital, Pohang, Korea

Correspondence Soo Young SY Kim ,Email: 1

Abstract

Purpose
: After repair of tetralogy of Fallot(TOF), ventricular arrhythmia and sudden death remain as serious late complications which are due to right ventricular systolic and diastolic overloading, exposure to hypoxia and surgical scar. Among the various methods for predicting the risk of such complications, we evaluated signal average ECG(SAECG), QRS duration, QT and JT dispersion, cardiothoracic(CT) ratio, age at repair and follow-up duration.
Methods
: Patients were divided into 3 groups : repaired TOF patients(group 1, n=22), patients with complete right bundle branch block(CRBBB) after ventricular septal defect and/or atrial septal defect repair(group 2, n=16) and normal controls(group 3, n=13). There were no significant differences in mean age at presentation, mean age at repair, or at mean follow up among the 3 groups.
Results
: QRS duration was significantly prolonged in group 1 and 2(121¡¾29ms, 119¡¾17ms, respectively) compared to group 3(81¡¾4ms)(P<0.01). In group 1, QRS duration showed significant positive correlations with age at repair(r=0.43, P<0.05) and follow-up duration(r=0.46, P<0.05). QT dispersion was significantly increased in group 1 and 2(88¡¾38ms, 71¡¾27ms, respectively) compared to group 3(37¡¾20ms)(P<0.01). JT dispersion showed significant differences among groups, being 96¡¾38ms in group 1, 68¡¾25ms in group 2, 44¡¾18ms in group 3(group 1 vs 2 : P<0.05, group 2 vs 3 : P<0.05, group 1 vs 3 : P<0.01). CT ratio was significantly increased in group 1(59¡¾6%) compared to group 2 and 3(50¡¾3%, 50¡¾2%, respectively)(P<0.01). There were no significant differences in parameters of SAECG among the 3 groups.
Conclusion
: We concluded that abnormality of JT dispersion, in repaired TOF pateints indicating inhomogeneity of repolarization, can be a cause of ventricular arrhythmia.

Keywords :Tetralogy of Fallot, Ventricular arrhythmia and sudden death, Signal average ECG, JT dispersion