QTc prolongation has been reported in adults following cardiopulmonary bypass; however, this phenomenon has not been studied in children with congenital cardiac disease. This study's aim was to formally assess QTc in children undergoing cardiac surgery.
Pre-operative and post-operative electrocardiograms during hospital stays were prospectively analysed on 107 consecutive patients under 18 years of age undergoing cardiac surgery. QTc was measured manually in leads II, V4, and V5. Measurements of 440 and 480 milliseconds were used to categorise patients. Peri-procedural data included bypass and cross-clamp time, medications, and electrolyte measurements. Outcome data included arrhythmias, length of mechanical ventilation, and hospital stay. Patients with post-operative new bundle branch block or ventricularly paced rhythm were excluded.
In all, 59 children were included, out of which 26 had new QTc over 440 milliseconds and 6 of 59 had new QTc over 480 milliseconds post-operatively. The mean increase in post-operative QTc was 25 milliseconds, p=0.0001. QTc over 480 was associated with longer cross-clamp time, p=0.003. Other risk factors were not associated with post-operative QTc prolongation. This phenomenon was transient with normalisation occurring in 67% of patients over 60 hours on average. One patient with post-operative QTc over 440 milliseconds developed ventricular tachycardia. There was no correlation between prolonged QTc and duration of mechanical ventilation, or hospital stay.
A significant number of children undergoing cardiac surgery showed transient QTc prolongation. The precise aetiology of QT prolongation was not discerned, though new QTc over 480 milliseconds was associated with longer cross-clamp time. In this cohort, transient QTc prolongation was not associated with adverse sequela.
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