The Effects of Propofol and Sevoflurane on the QT Interval and Transmural Dispersion of Repolarization in Children

Abstract

Prolongation of the QT interval is associated with torsades de pointes (TdP), especially in children or young adults with long QT syndromes. Susceptibility to TdP arises from increased transmural dispersion of repolarization (TDR) across the myocardial wall. Several anesthetic drugs prolong the QT interval, but their effect on TDR is unknown. TDR can be measured on the electrocardiograph (ECG) as the time interval between the peak and end of the T wave (Tp-e). We investigated the effects of propofol and sevoflurane on the corrected QT (QTc) and Tp-e intervals in 50 unpremedicated ASA physical status I-II children, aged 1-16 yr, who were randomized to receive propofol (group P) or sevoflurane (group S). Twelve-lead ECGs were recorded preoperatively and intraoperatively. Sevoflurane significantly prolonged the preoperative QTc; propofol did not. Neither anesthetic had any significant effect on the preoperative Tp-e. Sevoflurane increases the duration of myocardial repolarization in children to a larger extent than does propofol, but as the dispersion of repolarization appears unaffected, the risk of TdP is likely to be minimal with either anesthetic.

Effects of target concentration infusion of propofol and tracheal intubation on QTc interval*

“…However, the increased QTc interval was within normal limit and no patients in this study had an arrhythmia. These findings are inconsistent with those from previous studies, which reported that propofol has no effect on the QT interval [8][9][10][11]. Our results also contradict Paventi et al [12], and Kleinsasser et al [13], who hypothesised that propofol may shorten the QTc interval.…”

“…Slowly activating (iKs) and rapidly activating (iKr) delayed rectifier channels conduct most of the repolarisation current [21]. It is widely known that inhaled anaesthetic agents block iKr channels, and therefore increase the QTc interval in healthy patients [1,2,7,9,10]. There are no reports that have clearly investigated intravenous anaesthetics, including propofol's contribution to QTc prolongation, but according to Heath et al [22], propofol has been reported to block the delayed rectifier potassium current.…”

“…It is known that most inhalation anaesthetics or intravenous anaesthetics can influence the corrected QT (QTc) interval, and there have been many studies that investigated the different results of this effect [1,2,[7][8][9][10][11][12][13][14]. Some studies report that propofol causes QTc prolongation [14].…”

“…Some studies report that propofol causes QTc prolongation [14]. Conversely, some studies show that propofol has no effect [8][9][10][11] or decreases the QTc interval, and can therefore offset the QTc prolongation created by other anaesthetic drugs [12,13]. In many of these studies propofol was administered simultaneously with other agents within a short period of time; therefore, it is difficult to determine propofol's selective effect on the QTc interval.…”

Effects of sevoflurane on QT parameters in children with congenital sensorineural hearing loss

“…In both groups, sevoflurane lengthened the QTc and QTVI intervals but not Tp-e. Sevoflurane is a popular inhalational agent for general anaesthesia. It blocks the slowly activating delayed rectifier K current (I Ks ) and prolongs the QT interval in both children [1,2] and adults [3,4]. Such changes may be of clinical significance in patients presenting with long QT syndrome, hypokalaemia or in the presence of other agents or factors that lengthen the QT interval.…”