Prolongation of the QT Interval by Enflurane, Isoflurane, and Halothane in Humans

Abstract

Previous investigations in laboratory animals have documented the ability of the volatile anesthetics to prolong the QT interval and the QT interval corrected for level of heart rate, QTc. The purpose of the present investigation was to evaluate the direct electrocardiographic and hemodynamic effects of enflurane, isoflurane, and halothane in healthy, unpremedicated patients using an inhalation induction to avoid the confounding effects of other anesthetic agents. Experiments were conducted in 22 adult male patients, (ASA physical status I or II) divided into three groups given either enflurane (n = 6), isoflurane (n = 8), or halothane (n = 8) anesthesia. Twenty-four-hour preoperative, preinduction, and postinduction hemodynamic and electrocardiographic measurements were obtained. Anesthetic blood concentrations, levels of plasma electrolytes, and arterial blood gas tensions were also quantitated. Halothane administration (0.81 +/- 0.06 mM) did not significantly alter the PR interval or QRS duration but significantly increased the QT (0.38 +/- 0.01 to 0.45 +/- 0.01 s) and QTc intervals (0.39 +/- 0.01 to 0.44 +/- 0.02 s). Isoflurane anesthesia (1.04 +/- 0.11 mM) did not significantly change QRS duration or PR and QT intervals but significantly prolonged the QTc interval (0.42 +/- 0.01 to 0.47 +/- 0.14 s). Similarly, enflurane anesthesia (2.16 +/- 0.13 mM) significantly prolonged the QTc (0.40 +/- 0.01 to 0.46 +/- 0.14 s) without change in QRS duration or PR and QT intervals. Plasma electrolyte levels and arterial gas tensions remained within normal limits in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Long QT Syndrome: Frequency, Onset, and Risk Factors in Intensive Care Patients

“…[40][41][42][43] In our study, the patients with aLQTS often had the syndrome at the time of ICU admission (30%), or aLQTS developed soon after their admission to the unit (70%); the mean time of onset was 10.6 hours after ICU admission. Our sample included 8 patients who had major surgery and returned to the ICU from the operating room.…”

“…Clinicians have known for several decades that flurane can affect cardiac repolarization, leading to aLQTS. [39][40][41][42][43] Cases most often occur in older patients with predisposing risk factors such as electrolyte abnormalities and/or ischemic heart disease. 47,48 However, in a recently reported case, 49 ventricular tachycardic arrest developed in a healthy 35-year-old woman after QTc prolongation during a simple septoplasy with general anesthesia.…”

Effects of fentanyl pretreatment on the QTc interval during propofol induction

“…Evidence regarding the effects of propofol on the QTc interval is still conflicting [3,4], while thiopentone and most volatile anaesthetics are known to prolong the QTc interval [5][6][7]. During laryngoscopy and intubation, QTc prolongation may become exacerbated [8], which is thought to be caused by sympathetic stimulation.…”

Effects of Mechanical Ventilation on the Electrocardiogram in Adults

“…Alternatively, P-wave axis shifts may occur secondary to subtle shifts in sinus pacemaker activity related to autonomic effects [15]. The increase in QTc interval seen in this study has been reported as an effect of some inhaled anesthetics [16,17]. However, there is no report to our knowledge that associates any of the medications used in the present study with a prolonged QTc.…”