title: A case of transient 2:1 atrioventricular block, resolved by thyroxine supplementation for subclinical hypothyroidism.
abstract: A 42-year-old man was admitted to our hospital with palpitation attacks. Holter ECG showed 2:1 atrioventricular block and bradycardia with the minimum heart rate of 44 beats/min. There was a possible indication of electrophysiological study and cardiac pacemaker implantation. Laboratory data on admission revealed elevated thyrotropin level, with normal thyroxine level. To rule out functional atrioventricular block, we tried 2 weeks of the thyroxine supplementation, and Holter ECG showed improved heart rate without any atrioventricular block or long pause. We experienced that subclinical hypothyroidism caused severe bradycardia and 2:1 atrioventricular block, and that thyroxine supplementation completely improved these conditions.
authors.affiliation: Department of Cardiovascular Medicine, Japanese Red Cross Medical Center, Hiroo, Tokyo, Japan.
authors.forename: Yukiteru
authors.initials: Y
authors.lastname: Nakayama
authors.forename: Makoto
authors.initials: M
authors.lastname: Ohno
authors.forename: Shigeto
authors.initials: S
authors.lastname: Yonemura
authors.forename: Hiroki
authors.initials: H
authors.lastname: Uozumi
authors.forename: Naoshi
authors.initials: N
authors.lastname: Kobayakawa
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Fukushima
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Aoyagi
mesh_terms: D000328:Adult; D001919:Bradycardia / Q000188:drug therapy / Q000209:etiology; D015716:Electrocardiography, Ambulatory; D006327:Heart Block / Q000188:drug therapy* / Q000209:etiology*; D006801:Humans; D007037:Hypothyroidism / Q000150:complications* / Q000188:drug therapy*; D008297:Male; D013974:Thyroxine / Q000627:therapeutic use*
chemical_list: D013974:Thyroxine