Methods: Between October 2006 and March 2011, 279 consecutive patients (144 females, 135 males; mean age 56.6±5.0 months; range 15 days to 17 years) who met initial inclusion criteria and underwent congenital cardiac surgery were included. QTc dispersion measurements were calculated based on the standard 12-lead resting electrocardiograms of the patients in the preoperative (one month) and postoperative (one week) period.

Results: In 75.9% of all patients with cardiac surgery, postoperative QTc dispersion was statistically higher from preoperative QTc dispersion (p<0.001). Ventricular septal defect (VSD) (36.9%) and secundum atrial septal defect (ASD) (18.2%) were the most common congenital heart diseases in the study population. Repair of VSD, atrioventricular septal defect, tetralogy of Fallot, (TOF) and secundum ASD were the major risk factors for increased QTc dispersion. However, no statistical difference was found between pre- and postoperative QTc dispersion in children who underwent repair of VSD and pulmonary stenosis, end-toend anastomosis of aorta for coarctation, patent ductus arteriosus ligation and division, pulmonary banding, and Glenn procedure. The occurrence of arrhythmia in prolonged QTc dispersions according to the type of cardiac surgery was statistically higher from those without prolonged QTc dispersion.

Conclusion: QTc dispersion measurement is a useful noninvasive electrocardiographic test in the evaluation of arrhythmias. The study results suggest that use of QTc dispersion in the postoperative period may be helpful in the prediction of the development of arrhythmias.