Desflurane??s Effect on QTc Interval: Electrophysiological Mechanisms Need to Be Explored

To the Editor: Owczuk et al. (1) incorrectly state that their report is the first to describe the influence of desflurane on the QT interval. The influence of desflurane on the QT interval was reported by Yildirim et al. (2) several months earlier. Although the study by Owczuk et al. focuses only on QT correction for heart rate (QTc), the study by Yildirim et al. explores the effects of sevoflurane, isoflurane, and desflurane on various aspects of QT interval (2), including QT dispersion (QTD), heart rate corrected QT interval (QTc), and QTc dispersion of the electrocardiogram (QTcD). The effects of desflurane on QTc interval are comparable in both studies. One MAC of inhaled anesthetic causes a significant increase in QTc, QTD, and QTcD (2). Further electrophysiological studies are needed to determine whether the effects of desflurane on the QT interval are mediated by an increase in transmural dispersion of repolarization (e.g., halothane (3)) or a reduction in Ik current (e.g., sevoflurane) (4). Thiruvenkatarajan Venkatesan, MD, DA, DNB Christian Medical College Hospital Tamilnadu, India [email protected]