What question did this study set out to answer?

This study aims to evaluate the acute intravenous effects of several antiarrhythmic agents on canine atrial flutter.

April 1, 1995

Acute Intravenous Conversion of Canine Atrial Flutter

LBLewis V. BuchananBristol-Myers Squibb (United States)GKGlenn KabellWestern Michigan University JGJohn K. GibsonW.E. Upjohn Institute for Employment Research

Key Points

This study aims to evaluate the acute intravenous effects of several antiarrhythmic agents on canine atrial flutter.
Used a canine Y-shaped right atrial incision model of atrial flutter with 25 dogs.
Administered sequential doses of ibutilide, sematilide, lidocaine, and encainide every 5 minutes after baseline determination of atrial effective refractory period (AERP).
Monitored AFL cycle length (CL) and reinitiation of AFL post-treatment.
Ibutilide increased AFL cycle length by 26 ms and successfully terminated AFL in all 8 treated dogs (dose: 6 mg/kg).
Sematilide increased AFL cycle length by 12 ms and terminated AFL in 4 of 8 dogs (dose: 0.6 mg/kg).
Encainide significantly increased AERP by 77 ms and terminated AFL in 3 of 4 dogs (dose: 3 mg/kg).

Abstract

We studied the acute intravenous (i.v.) effects of the antiarrhythmic agents ibutilide, sematilide, lidocaine, and encainide in a canine Y-shaped right atrial incision model of atrial flutter. After baseline determination of atrial effective refractory period (AERP), sustained atrial flutter (AFL) was initiated by atrial pacing in 25 dogs. Each dog then received placebo, followed by sequential doses of a particular agent every 5 min until AFL was terminated or the highest dose was administered. Ibutilide increased AFL cycle length (CL: 26 +/- 6 ms) before termination of AFL in 8 of 8 dogs in 1 min after the effective dose (6 +/- 1 micrograms/kg). AERP determined immediately after termination of AFL was significantly increased (44 +/- 7 ms). AFL could not be reinitiated after termination with ibutilide. Sematilide increased AFL CL 12 +/- 6 ms, significantly increased AERP 25 +/- 6 ms, and terminated AFL in 4 of 8 dogs (0.6 +/- 0.2 mg/kg). After sematilide or pacing-induced termination, AFL was reinducible in only 1 dog. Lidocaine terminated AFL in 2 of 5 dogs (2.0 +/- 0.5 mg/kg). AERP was unchanged in both animals, and AFL CL increased by 37 +/- 3 ms. AFL was reinducible in all 5 lidocaine-treated dogs after AFL was terminated. Encainide terminated AFL in 3 of 4 dogs after a dose of 3.0 +/- 0.0 mg/kg. AERP was significantly increased 77 +/- 10 ms, and AFL CL was markedly increased by 226 +/- 11 ms. AFL could not be reinitiated after termination of AFL by encainide.(ABSTRACT TRUNCATED AT 250 WORDS)

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