Evaluation of electrocardiographic changes after arterial switch operation.

Background: Transposition of Great Arteries (TGA) is a serious congenital heart disease which can be accompanied by good outcomes with anatomic correction within the first few weeks of life.

Objectives: The present study aimed to evaluate electrocardiographic changes in the children with uncomplicated Arterial Switch Operation (ASO).

Patients and methods: Twelve lead electrocardiograms were obtained from thirty-three patients with TGA after ASO. Then, the patients' QT-dispersion and P-wave dispersion were compared to those of 33 age- and gender-matched individuals as the normal control group. Both groups were also evaluated by M-mode echocardiography. Student's t-test and Pearson correlation were used to analyze the data. Besides, P < 0.05 was considered as statistically significant.

Results: The mean age of the patients and the control group was 41 ± 3.7 and 40.12 ± 4.2 months, respectively. Comparison of P wave, T wave, QRS complex, PR interval, QT segment, and corrected QT segment showed significant differences in the frequency of inverted T wave in pericardial leads [V3, V4, V5, and V6] (P = 0.004; more in patients), P wave amplitude in lead II (P < 0.001; more in patients), R wave amplitude in V1 (P = 0.016; smaller in patients), R and S waves amplitude in V6 (P = 0.004 and P = 0.001; taller in patients), corrected QT segment (in lead V5; P < 0.0001: prolonger in patients), and PR interval (P = 0.001; prolonger in patients). However, no significant differences were found regarding the vector axis and heart rate. Right bundle branch block (18% vs. 0%), Bifascicular (3% vs. 0%), and first-degree blocks (15% vs. 0%) were significantly more in the patients. Besides, the PR interval was longer in the corrected complex TGA (146 ± 24.4 vs. 127.7 ± 23.1, P = 0.001). Moreover, R/S ratio in lead V1 was significantly prolonger, among the patients (2.86 ± 3.35 vs. 0.706 ± 0.53, P = 0.002). Nonetheless, no significant was observed between the patients and controls concerning the mean of QT dispersion. On the other hand, the two groups were significantly difference in terms of P wave dispersion (25.7 ± 13.8 vs. 33.74 ± 12.9, P = 0.024).

Conclusions: In this study, first-degree block and right bundle branch were detected in the operated patients with TGA. Increased P dispersion in these patients may increase the risk of atrial arrhythmia. Thus, long-term follow-up is necessary in these patients.