[Atrioventricular block in acute inferior myocardial infarction]

The underlying mechanism of atrioventricular block (AVB) in acute inferior myocardial infarction (AIMI) is not clearly understood. In 33 (27 males and 6 females) of 123 patients with AIMI, second and/or high degree AVB was observed. In 14 of the 33 patients (42%), AVB transiently appeared within 24 hours after the onset of AIMI. In 13 patients (39%) AVB appeared after 24 hours. In the remaining 6 patients (18%), AVB appeared within 24 hours and disappeared thereafter. Among these 3 groups, there were no significant differences in age, sex, serum enzymes, the appearance of high degree AVB, pump failure or Forrester's classification II, III and IV and the necessity of temporary pacing. One mg of atropine sulfate was administrated intravenously 35 times in 19 patients. When AVB improved or the ventricular rate increased more than 30%, the drug was regarded as effective. Atropine was more effective when administrated after 24 hours (11%, less than or equal to 24 hours vs 60%, greater than 24 hours, p less than 0.05), and in patients with a slight degree of AVB (28% in high degree vs 80% in second degree, p less than 0.05) and rapid ventricular rate during high degree AVB (0%, less than 40/min vs 45%, greater than or equal to 40/min, p less than 0.05). In the 6 patients not responding to atropine, 250 mg of aminophylline was given intravenously for 15 min. The effect was not seen in 4 patients, including 3 patients to whom it was administrated within 3 days after the onset of AIMI, and one patient to whom it was given on the 5th day. Aminophylline improved atrioventricular conduction on the 5th to 10th day after the onset of AIMI in 2 patients.(ABSTRACT TRUNCATED AT 250 WORDS)