Some Points Regarding Anesthesia for Patients with Congenital Long QT Syndrome

Abstract

State University of New York at Stony Brook, Stony Brook, New York. rikatz@aol.comI read with great interest the article by Kies et al. in the January 2005 issue of Anesthesiology entitled “Anesthesia for Patients with Congenital Long QT Syndrome.” The article is a good review of the subject, but it omits a number of important points regarding the perioperative care of patients with this disease. First, it should be noted that no studies exist comparing the safety of anesthetic agents in long QT syndrome (LQTS). The recommendations are therefore extrapolated from case reports and studies from healthy volunteers. Although isoflurane may indeed shorten the QT interval more than other agents, significant arrhythmias in LQTS patients anesthetized with isoflurane have been reported. A number of reports on this subject3,4 have noted that the most prevalent factor associated with significant arrhythmias during surgery and anesthesia is the lack of control of symptoms before surgery. Although halothane and ketamine should probably be avoided, patients whose arrhythmias are well controlled before surgery rarely have arrhythmias during surgery, regardless of the anesthetic technique chosen.Second, Kies et al. do acknowledge that different genetic subtypes of LQTS are known to exist. However, optimal treatments of the various subtypes differ in important and significant ways. LQTS types 1 and 2 (LQT-1 and LQT-2) are defects on chromosomes 11 and 7, respectively, both encoding for potassium transmission. The standard treatment for both has been β-blockade. β-Blockade may, however, be contraindicated in LQT-3 (a defect in sodium transmission), because bradycardia in these patients can further prolong the QT interval and lead to ventricular arrhythmias. In 1991, Moss et al. showed that cardiac pacing at a rate sufficient to shorten the QT interval could prove useful in LQTS. This article was written before the genetic subtypes of the condition were known, and the data of Schwartz et al. suggest that cardiac pacing might be particularly useful in LQT-3.Kies et al. do mention the possibility of droperidol prolonging the QT interval. However, numerous drugs do the same and should probably be avoided in patients with LQTS. Those likely to be encountered in the operating room include amiodarone, disopyramide, chlorpromazine, dolasetron, haloperidol, tamoxifen, and many others.Although genetic testing is still not easily obtainable, it should be noted that it is often possible to distinguish among the various subtypes of LQTS by the electrocardiographic pattern. LQT-1 has a prolonged QT interval with a normal to high T-wave amplitude, a broad-based T wave, and an indistinct T-wave onset. LQT-2 is characterized by a prolonged QT interval, low-amplitude T waves, and bifid T waves in more than 60% of cases. LQT-3 shows a prolonged QT interval with late onset, peaked T waves, and a long, isoelectric ST segment.Last, despite all efforts, arrhythmic episodes, particularly torsade de pointes, are common in LQTS patients. Kies et al. do not give specific recommendations for dealing with such arrhythmias when they occur, but intravenous magnesium; intravenous lidocaine; rapid-acting β-blocking medications, such as esmolol in LQT-1 and -2; and, in LQT-3 patients, cardiac pacing may be effective, and in all cases, the equipment for emergency electrical defibrillation should be present.State University of New York at Stony Brook, Stony Brook, New York. rikatz@aol.com