Brief Communication Complete heart block with ventricular asystole during left vagus nerve stimulation for epilepsy Imran I. Ali, a, * Noor A. Pirzada, a Yousuf Kanjwal, a Braxton Wannamaker, c Azedine Medhkour, a Michael T. Koltz, a and Bradley V. Vaughn b a Department of Neurology, Medical College of Ohio, Toledo, OH 43614, USA b Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7025, USA c Department of Neurology, Regional Medical Center of Orangeburg and Calhoun Counties, Orangeburg, SC 29115, USA Received 1 March 2004; revised 19 May 2004; accepted 21 May 2004 Available online 2 July 2004 Abstract Vagus nerve stimulation (VNS) is an important therapeutic option for individuals with refractory epilepsy who have failed multiple antiepileptic drugs (AEDs). The intricate relationship of the vagus nerve to cardiac function raises concern that vagal stimulation may affect cardiac rhythm and function. Previous pre- and postmarketing studies have not shown this to be a significant problem, with the incidence of bradyarrhythmias reported to be about 0.1%. We review three cases of ventricular asystole with complete heart block that occurred during intraoperative lead tests. The purpose of these case reports is to identify the specific type of cardiac abnormality associated with vagus nerve stimulation and to identify individuals at risk. Ó 2004 Elsevier Inc. All rights reserved. Keywords: Vagus nerve stimulation; Autonomic nervous system; Ventricular asystole; Atrioventricular nodal block 1. Introduction Vagus nerve stimulation (VNS) is an established therapeutic option for patients with refractory epilepsy [1,2]. More than 16,000 implants have been performed worldwide [3]. In one of the earlier trials (EO3), the mean decrease in seizure frequency was 24.5% in the high intensity and frequency stimulation group and 6.1% in the low intensity and frequency stimulation group [4]. In the same study the percentage of patients with at least 50% reduction in seizures was 31% in the high stimulation group and 15% in the low stimulation group. Subsequent 5-year data suggest that the re- sponse rate is similar to that in the earlier pivotal studies [5,6]. In a vast majority of patients in these trials the ad- verse events have been mild and transient [7]. A review of available literature suggests that the cardiac or re- spiratory problems that theoretically may be a concern with vagus nerve stimulation are rarely of clinical sig- nificance [5–10]. The incidence of sudden unexplained, unexpected death in epilepsy (SUDEP) in patients with VNS implants was found to be similar to that in patients with refractory epilepsy who did not have the implant [11]; in fact, in the 2-year extension phase of that study the rate of SUDEP dropped from 5.5 per 100,000 to 1.7 per 100,000 [12]. However, two recent reports suggest that cardiac arrhythmias may occur in a subset of pa- tients, but are usually transient and self-limiting and do not necessarily prevent use of this device [13,14]. We report three cases of complete heart block that occurred in patients with refractory epilepsy in the perioperative period during the initial lead test. The underlying cardiac rhythm was a complete heart block with ventricular asystole that occurred for 6–15 s and resolved without any intervention. Ours is the first se- ries that documents the actual cardiac abnormalities observed in association with left vagus nerve stimu- lation. * Corresponding author. Fax: 1-419-383-3093. E-mail address: iali@mco.edu (I.I. Ali). 1525-5050/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.yebeh.2004.05.008 Epilepsy & Behavior 5 (2004) 768–771 Epilepsy & Behavior www.elsevier.com/locate/yebeh