title: Low energy synchronous transcatheter cardioversion of atrial flutter/fibrillation in the dog.
abstract: The feasibility and effectiveness of low energy synchronous transcatheter cardioversion of atrial flutter and fibrillation were examined in dogs with talc-induced pericarditis. A conventional electrode catheter was positioned transvenously in the right atrial appendage. Atrial flutter/fibrillation was induced by using the train pulse method, and the tachyarrhythmia-inducing threshold was determined. The minimal effective cardioversion energy levels were compared in three different cardioversion methods: method A = delivery of shock between the proximal electrode (cathode) and the backplate (anode), method B = delivery between the proximal electrode (cathode) and the distal electrode (anode) and method C = conventional external cardioversion. In both methods A and B, all 149 cardioversion attempts were successful with shocks of less than or equal to 5 J. Shocks of less than or equal to 1 J resulted in successful cardioversion in 57 (70%) of 81 attempts, 50 (74%) of 68 attempts and 5 (12%) of 41 attempts with methods A, B and C, respectively. The mean minimal effective cardioversion energy levels were not significantly different between methods A and B (0.62 +/- 0.67 versus 0.58 +/- 0.71 J). Transcatheter cardioversion decreased the defibrillation threshold 3- to 75-fold (mean 6- to 7-fold) from that of transthoracic cardioversion. The defibrillation threshold was not influenced by the inducibility of atrial flutter/fibrillation. There were no complications of heart block, ventricular fibrillation or pathologic evidence of severe shock-induced atrial injury. Thus, low energy synchronous transcatheter cardioversion of atrial flutter/fibrillation is considered feasible and effective. This technique may also be useful in managing the atrial flutter/fibrillation that can occur during electrophysiologic studies.
authors.affiliation: Department of Internal Medicine, School of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kumagai
authors.forename: Y
authors.initials: Y
authors.lastname: Yamanouchi
authors.forename: N
authors.initials: N
authors.lastname: Tashiro
authors.forename: T
authors.initials: T
authors.lastname: Hiroki
authors.forename: K
authors.initials: K
authors.lastname: Arakawa
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000628:therapy*; D001282:Atrial Flutter / Q000628:therapy*; D006328:Cardiac Catheterization; D004285:Dogs; D004554:Electric Countershock / Q000379:methods*