title: Apparent bradycardia-dependent advanced second-degree atrioventricular block.
abstract: A 65-year-old man with repeated chest discomfort and dizzy spells was transferred by an emergency car. On the way to hospital, his pulse was palpable as regular 4 to 5 beats followed by an unpalpable period of about 4 s. His electrocardiographic monitor showed that 4 to 5 sinus QRS complexes were followed by consecutive 3 to 4 blocked sinus P waves, which occurred repeatedly. When PP intervals gradually shortened during inspiration, sinus impulses were conducted to the ventricles, whereas when PP intervals lengthened during expiration, 3 to 4 sinus impulses were blocked in succession. An attempt was made to explain the mechanism for such apparent bradycardia-dependent atrioventricular block by using the concepts of periodic increases in vagal tone due to respiration and concealed electrotonic conduction of blocked impulses. Such a peculiar form of advanced second-degree atrioventricular block has never been reported before.
authors.affiliation: Katoh Cardiovascular Clinic, Ohtsu, Japan.
authors.forename: Takakazu
authors.initials: T
authors.lastname: Katoh
authors.forename: Shinji
authors.initials: S
authors.lastname: Kinoshita
authors.forename: Ichirou
authors.initials: I
authors.lastname: Ueji
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Tsujimura
mesh_terms: D000368:Aged; D001919:Bradycardia / Q000150:complications* / Q000503:physiopathology; D004562:Electrocardiography; D006327:Heart Block / Q000209:etiology* / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male