Atropine-induced multilevel block in acute inferior myocardial infarction. A possible indication for prophylactic pacing.

Abstract

The degree of A-V block increased after intravenous administration of atropine in 10 nondigitalized patients with acute inferior myocardial infarction who had narrow QRS complexes during periods of 1:1 A-V conduction. Short episodes of 3:1, 4:1 and 5:1 A-V block were seen to emerge: (a) in 6 patients, directly from Wenckebach periods; (b) in 3 patients, from alternating Wenckebach periods; and (c) in 1 patient, from a 3:2 Wenckebach period which led to a short-lived alternating Wenckebach period. Apparently, the predominance of the chronotropic effects on the sinus node over the dromotropic effects on the A-V node led to a tachycardia-dependent (more ischemic than vagal) process, exposing or producing multi- (two, three or four) level block involving the A-V node (and perhaps the His bundle). Subsequently, therapeutic pacing was instituted in 9/10 patients because they developed spontaneous symptomatic advanced A-V block. Therefore, it is possible that the early effects of atropine identified a narrowly-defined subset of patients in whom prophylactic pacing may be indicated. However, more studies are necessary to corroborate these assumptions.

• Authors: A Castellanos, H G Garcia, J J Rozanski, L Zaman, K Pefkaros, R J Myerburg
• Journal: Pacing and clinical electrophysiology : PACE (Pacing Clin Electrophysiol) Vol. 4 Issue 5 Pg. 528-37 (Sep 1981) ISSN: 0147-8389 [Print] United States
• PMID: 6169039 (Publication Type: Journal Article)

Chemical References

• Atropine

Topics

• Atropine (adverse effects)
• Cardiac Pacing, Artificial
• Depression, Chemical
• Heart Block (chemically induced, complications, therapy)
• Heart Rate (drug effects)
• Humans
• Myocardial Infarction (complications)