High-density mapping of pulmonary veins and left atrium during ibutilide administration in a canine model of sustained atrial fibrillation.
Ibutilide can prolong refractory period and terminate reentry. Whether ibutilide has the same effects on pulmonary vein (PV) focal discharge (FD) is unclear. We induced sustained atrial fibrillation (AF) in seven dogs by rapid left atrial (LA) pacing for 74 +/- 46 days. Ibutilide was repeatedly infused until it terminated AF (0.02 +/- 0.01 mg/kg) or when a cumulative dose was reached (0.04 mg/kg). High-resolution computerized epicardial mapping was performed. We found intermittent FD at the PVs and reentry at the PV-LA junction during AF. Ibutilide increased the cycle length of consecutive reentry from 97 +/- 13 to 112 +/- 18 ms and increased FD from 96 +/- 7 to 113 +/- 9 ms. In four dogs with both FD and reentry at the PVs, the incidence of reentry decreased from 3.5 +/- 1.9/s at baseline to 2.2 +/- 1.8/s after ibutilide administration. However, the incidence of FD remained unchanged. The conducted wave fronts between PV and LA were significantly reduced by ibutilide (10.4 +/- 2.0/s vs. 8.0 +/- 1.6/s). The ibutilide dose needed to terminate AF correlated negatively with the baseline effective refractory period of PV and LA. We conclude that ibutilide reduces reentrant wave fronts but not PV FD in a canine model of pacing-induced sustained AF. These findings suggest that the PV FD during AF is due to nonreentrant mechanisms. High doses of ibutilide may completely terminate all reentrant activity, converting AF to PV tachycardia before the resumption of sinus rhythm.
Chou
Chung-Chuan
CC
Division of Cardiology, Department of Medicine, Rm. 5537, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA.
Zhou
Shengmei
S
Tan
Alex Y
AY
Hayashi
Hideki
H
Nihei
Motoki
M
Chen
Peng-Sheng
PS
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology*; D018780:Body Surface Potential Mapping / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D006325:Heart Atria / Q000187:drug effects / Q000503:physiopathology*; D006329:Heart Conduction System / Q000187:drug effects / Q000503:physiopathology*; D011667:Pulmonary Veins / Q000187:drug effects / Q000503:physiopathology*; D013449:Sulfonamides / Q000008:administration & dosage*; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D013449:Sulfonamides; C067192:ibutilide