Apparent bradycardia-dependent advanced second-degree atrioventricular block.
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.
Katoh
Takakazu
T
Katoh Cardiovascular Clinic, Ohtsu, Japan.
Kinoshita
Shinji
S
Ueji
Ichirou
I
Sasaki
Yoshihiko
Y
Tsujimura
Yoshinori
Y
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