The Effects of Volatile Anaesthetic Agents in Myocardial Repolarization During Induction of Anaesthesia

Abstract

QT dispersion may serve as a measure of variability in ventricular repolarization time and may be a means of identifying patients at risk of arrhythmias and sudden death after different clinical settings. The acute responses of QTc dispersion were assessed in 47 American Society of Anesthesiology (ASA) class 1 or 2 patients receiving volatile anaesthetic agents. Anaesthesia was induced with sevoflurane (n=16), halothane (n=17), or isoflurane (n=14), and the inspired concentration increased to reach an end- tidal concentration of 1% to 6%. Recordings of ECG, heart rate, blood pressures were obtained at the following times: prior to induction of anaesthesia, 1 min and 3 min after stable end-tidal concentration, 1 min and 3 min later vecuronium administration, and 1 min and 3 min after tracheal intubation. All the patients studied had normal values of QTc interval and QTc dispersion at rest. All anaesthetic agents significantly increased QTc dispersion compared with baseline values. Both isoflurane and sevoflurane increased QTc interval compared with baseline in contrast to halothane which did not change it significantly. Thus, anaesthetic agents cause myocardial repolarization abnormalities in man in terms of increased QTc dispersion. This may be relevant in the aetiology of arrhythmias in patients receiving anaesthesia without cardiovascular disease.