title: Reversible infra-Hisian atrioventricular block in acute myocarditis.
abstract: Symptomatic second- or third-degree atrioventricular (AV) block at any anatomical level is a class I indication for permanent pacemaker implantation. We describe a 44-year-old male with acute viral myocarditis who suffered from syncope followed by a seizure attack associated with AV conduction disturbance. His initial electrocardiogram in our emergency room revealed sinus tachycardia with 2:1 AV conduction and a right bundle branch block QRS morphology with a ventricular rate of 60 beats/min. Because of episodic slowing of the heart rate below 40 beats/min, he received 1 mg atropine intravenously which increased the atrial rate but further worsened the AV conduction, resulting in ventricular asystole for more than 30 seconds associated with loss of consciousness and seizure-like activity. He was immediately paced transcutaneously and transferred to the catheterization laboratory to receive temporary transvenous cardiac pacing. The cardiac catheterization study showed a normal coronary angiogram and very mild diffuse hypokinesis. Electrophysiological studies revealed advanced infra-Hisian AV block. The infra-Hisian AV block, however, resolved rapidly in 2 days. The patient did not receive a permanent pacemaker and remained asymptomatic with normal electrocardiogram over 1 year of follow-up. We suggest that symptomatic infra-Hisian AV block due to viral myocarditis can be reversible, and implantation of a permanent pacemaker may not be necessary.
authors.affiliation: Division of Cardiology, Chang Gung Memorial Hospital, 123, Ta-Pei Road, Niaosung, Kaohsiung, Taiwan, R.O.C.
authors.forename: T H
authors.initials: TH
authors.lastname: Yu
authors.forename: G F
authors.initials: GF
authors.lastname: Guo
authors.forename: M C
authors.initials: MC
authors.lastname: Chen
authors.forename: C H
authors.initials: CH
authors.lastname: Yang
mesh_terms: D000208:Acute Disease; D000328:Adult; D004562:Electrocardiography; D006327:Heart Block / Q000209:etiology*; D006801:Humans; D008297:Male; D009205:Myocarditis / Q000150:complications*