Monophasic action potentials during reentrant atrial flutter in the dog: effects of clofilium and acetylcholine

Journal of Cardiovascular Pharmacology
K M WuB F Hoffman

Abstract

Monophasic action potentials (MAP) were recorded from canine atrium during reentrant flutter resulting from circus movement in atrial tissue above the tricuspid ring. A catheter and plaque contact electrodes were developed to record MAP from the epicardium or endocardium during sinus rhythm, paced rhythms, and flutter. The transmembrane action potential duration of tricuspid ring tissue also was studied in vitro. During flutter at cycle lengths of 140-160 ms, MAP showed incomplete repolarization. Pacing at comparable cycle lengths had a similar effect. Acetylcholine (10 micrograms/kg, i.v.) shortened MAP duration during pacing and, during flutter, decreased cycle length and increased MAP amplitude. Clofilium (500 micrograms/kg, i.v.) prolonged flutter cycle length by 18% and terminated the flutter within 30-120 s. During pacing at a cycle length of 300 ms, clofilium increased MAP duration and effective refractory period (ERP) by 30%. Transmembrane action potentials showed that clofilium (0.2 mg/L) modified only action potential duration. Conduction velocity was significantly decreased by clofilium during flutter but not during pacing at a cycle length of 300 ms. These data support the conclusion that in this model of flutter, t...Continue Reading

Citations

Sep 1, 1994·British Journal of Pharmacology·G S FriedrichsB R Lucchesi
Dec 1, 1992·Pacing and Clinical Electrophysiology : PACE·B OlshanskyR J Hariman
Nov 4, 1995·Journal of Interventional Cardiology·P A Boyden
Mar 1, 1996·Journal of Cardiovascular Pharmacology·Q LiU Ravens

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