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Updated: Jul 29, 2026

Programmed Electrical Stimulation in Mice
Published on: May 26, 2010
Intermittent fascicular extrasystoles producing pseudo AV block: electrophysiologic effects of beta agonists and
P C Nalos1, W J Mandel, E S Gang
1Department of Cardiology, Cedars-Sinai Medical Center, Los Angeles, California 90048.
Abstract:
This report describes a patient with pseudo-type II second-degree AV block due to an intermittent parasystolic focus located in the left bundle branch. A paradoxical increase in the fascicular rate was seen following intravenous propranolol, and fascicular extrasystoles were suppressed after intravenous isoproterenol treatment. All propagated fascicular extrasystoles were conducted to the ventricle with incomplete or complete right bundle branch block and a decrease in the H'-V interval compared to the H-V interval during sinus rhythm. Treatment with oral quinidine abolished fascicular extrasystoles without worsening of AV conduction.
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