QT DISPERSION OF CHILDREN BEFORE AND
AFTER SURGICAL CORRECTION OF VENTRICULAR SEPTAL DEFECTS
Ho TF1, Zhang N1,
Yip WCL1,2, Chan KY2
1 National
University of Singapore, Singapore
2
Gleneagles Medical Centre, Singapore
Objective: Our aim was to determine
QT interval and QT dispersion (QTd) in children before and after surgical
repair of ventricular septal defects (VSD).
Methods: Seventy children with VSD and 70 age-matched healthy controls
were studied. QT intervals were manually measured from each lead in every
resting 12-lead ECG set. QTd was calculated as the difference between the
maximum and minimum QT in each set of ECG. Corrected QT (QTc) and QRS
intervals were measured from lead II.
Results: Patients had either right atriotomy (71%), ventriculotomy (22%)
or transpulmonary (7%) approaches. Preoperatively, children with VSD had
significantly prolonged mean QT interval, QTd and QRS compared to healthy
controls. Mean QTc at 1-6 months post-operation was significantly higher
than pre-operative QTc (441¡À37 vs
411¡À29 msec,
p<0.001) but improved with follow-up. Mean QTd within 1 month after
operation was significantly higher than the pre-operative value (51¡À29 vs 43¡À29
msec, p<0.05). Larger proportions of children with ventriculotomy (73%)
or transpulmonary (67%) approach developed right bundle branch block and
had significantly more prolonged QTc and QTd.
Conclusion: Children with VSD may have prolonged ventricular depolarization,
repolarisation, with inhomogeneity of repolarisation possibly contributed
by conduction disturbances and surgical techniques.