Abstract 17259: Novel Multiple-Stage Low-voltage Atrial Defibrillation Therapy in a Canine Vagally-Mediated Atrial Fibrillation Model
Introduction: The implantable device therapy for atrial fibrillation (AF) is limited due to pain caused by high-voltage shocks. We aimed to develop a low-voltage, potentially painless defibrillation method for AF.
Methods: The 1 stage of multiple-stage therapy consisted of 2–10 monophasic (MP, 10 ms) or biphasic (BP, 6/4 ms) shocks (10–100V) applied over 1–2 cycle lengths of AF. The 2 stage consisted of 6–10 MP shocks (1–6V) with an interval of 70–100% that of AF CL. The 3 stage consisted of 6–10 bipolar right atrial pacing stimuli. In 6 canines we used 2 1in disk electrodes placed on the right and left atrial appendages (RAA, LAA). AF was induced by the rapid pacing during bilateral 10–20Hz vagal stimulation. We used a RAA-LAA vector for 1 stage therapy with or w/o a 3rd stage. In next 6 canines, an additional 0.5in disk electrode was placed on superior vena cava (SVC), and 4F 1in coils were implanted in distal and proximal coronary sinus (CSd, CSp). Shocks were applied from three vectors: SVC to CSd, LAA to CSp, and LAA to RAA. Three combinations of the stages were tested randomly: 1, 1–3, and 1–2–3.
Results: Sustained AF had dominant frequency of 10.3 ± 1.5 Hz. Defibrillation threshold (DFT) of 1BP and 1MP was 0.73 ± 0.43 and 1.68 ± 0.98 J (p = .008), respectively. DFT of 2BP was lower than that of 2MP (0.37 ± 0.14 vs. 0.93 ± 0.59 J, p = .01). DFT of 2BP was lower than that of 1BP (0.37 ± 0.14 vs. 0.73 ± 0.43 J, p = .04). DFTs of 4BP and 3BP were higher than that of 2BP (p=ns). Addition of 3 stage to 2BP lowered DFT (0.23 ± 0.05 vs. 0.5 ± 0.08 J, p = .001). The 1–2–3 therapy had the lowest DFT at 0.097 ± 0.070 J compared to 1 and 1–3 combinations. There was no statistical difference in 1–2–3 DFT among the three vectors.
Conclusions: Three-stage atrial defibrillation therapy has 0.1J DFT in the canine vagally-medicated model of AF, which opens an opportunity for pain-free atrial defibrillation.
- © 2010 by American Heart Association, Inc.