['Droperidol is useful for postoperative sedation in infants and children after cardiac surgery because it provides sedation and akinesia with minimal respiratory depression. However, droperidol has been associated with QT prolongation and ventricular arrhythmias. We investigated, if neuroleptanalgesic doses of droperidol led to QT prolongation and cardiac arrhythmias in children undergoing cardiac surgery.', 'We retrospectively analysed electrocardiogram rhythm strips that were obtained before and in time increments after a 100 microg x kg(-1) intravenous bolus of droperidol in 20 children undergoing cardiac surgery. The longest QT interval was determined in each ECG and corrected for heart rate (QTc). All arrhythmias were recorded.', 'Droperidol led to a significant increase in QTc time that was still present at 15 min but had resolved within 30 min after the bolus. No associated arrhythmias were observed.'] Does droperidol for perioperative sedation cause a transient prolongation of the QTc time in children under volatile anesthesia?