Induction of atrial tachycardia and fibrillation in the mouse heart.
BACKGROUND
Atrial tachycardia and fibrillation in humans may be partly consequent to vagal stimulation. Induction of fibrillation in the small heart is considered to be impossible due to lack of a critical mass of > 100-200 mm2. Even with the recent progression of the technology of in vivo and in vitro mouse electrophysiological studies, few reports describe atrial tachycardia or fibrillation in mice. The purpose of this study was to attempt provocation of atrial tachyarrhythmia in mice using transvenous pacing following cholinergic stimulation.


RESULTS
In vivo electrophysiology studies were performed in 14 normal mice. A six-lead ECG was recorded from surface limb leads, and an octapolar electrode catheter was inserted via jugular vein cutdown approach for simultaneous atrial and ventricular endocardial recording and pacing. Atrial tachycardia and fibrillation were inducible in one mouse at baseline electrophysiology study and eleven of fourteen mice after carbamyl choline injection. The mean duration of atrial tachycardia was 126 +/- 384 s. The longest episode lasted 35 min and only terminated after atropine injection. Reinduction of atrial tachycardia after administration of atropine was not possible.


CONCLUSIONS
Despite the small mass of the normal mouse atria, sustained atrial tachycardia and fibrillation can be easily and reproducibly inducible with endocardial pacing after cholinergic agonist administration. This finding may contribute to our understanding of the classical theories of arrhythmogenesis and critical substrates necessary for sustaining microreentrant circuits. The techniques of transcatheter parasympathetic agonist-mediated atrial tachycardia induction may be valuable in further murine electrophysiological studies, especially mutant models with potential atrial arrhythmia phenotypes.
Wakimoto
H
H
Department of Cardiology, Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
Maguire
C T
CT
Kovoor
P
P
Hammer
P E
PE
Gehrmann
J
J
Triedman
J K
JK
Berul
C I
CI
D000818:Animals; D001281:Atrial Fibrillation / Q000209:etiology* / Q000503:physiopathology; D001341:Autonomic Nervous System / Q000503:physiopathology; D002217:Carbachol / Q000494:pharmacology; D002304:Cardiac Pacing, Artificial; D002316:Cardiotonic Agents / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004195:Disease Models, Animal; D004562:Electrocardiography; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013610:Tachycardia / Q000209:etiology* / Q000503:physiopathology
D002316:Cardiotonic Agents; D018679:Cholinergic Agonists; D002217:Carbachol