title: Low-energy multistage atrial defibrillation therapy terminates atrial fibrillation with less energy than a single shock.
abstract: BACKGROUND
  Implantable device therapy of atrial fibrillation (AF) is limited by pain from high-energy shocks. We developed a low-energy multistage defibrillation therapy and tested it in a canine model of AF.
  
  
  RESULTS
  AF was induced by burst pacing during vagus nerve stimulation. Our novel defibrillation therapy consisted of 3 stages: stage (ST) 1 (1-4 low-energy biphasic [BP] shocks), ST2 (6-10 ultralow-energy monophasic [MP] shocks), and ST3 (antitachycardia pacing). First, ST1 testing compared single or multiple MP and BP shocks. Second, several multistage therapies were tested: ST1 versus ST1+ST3 versus ST1+ST2+ST3. Third, 3 shock vectors were compared: superior vena cava to distal coronary sinus, proximal coronary sinus to left atrial appendage, and right atrial appendage to left atrial appendage. The atrial defibrillation threshold (DFT) of 1 BP shock was <1 MP shock (0.55 ± 0.1 versus 1.38 ± 0.31 J, P=0.003). Two to 3 BP shocks terminated AF with lower peak voltage than 1 BP or 1 MP shock and with lower atrial DFT than 4 BP shocks. Compared with ST1 therapy alone, ST1+ST3 lowered the atrial DFT moderately (0.51 ± 0.46 versus 0.95 ± 0.32 J, P=0.036), whereas 3-stage therapy (ST1+ST2+ST3) dramatically lowered the atrial DFT (0.19 ± 0.12 versus 0.95 ± 0.32 J for ST1 alone, P=0.0012). Finally, the 3-stage therapy was equally effective for all studied vectors.
  
  
  CONCLUSIONS
  Three-stage electrotherapy significantly reduces the AF DFT and opens the door to low-energy atrial defibrillation at or below the pain threshold.
authors: Department of Biomedical Engineering, Washington University School of Medicine, St Louis, MO 63130, USA.
authors: Wenwen
authors: W
authors: Li
authors: Ajit H
authors: AH
authors: Janardhan
authors: Vadim V
authors: VV
authors: Fedorov
authors: Qun
authors: Q
authors: Sha
authors: Richard B
authors: RB
authors: Schuessler
authors: Igor R
authors: IR
authors: Efimov
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D016275:Atrial Function; D002304:Cardiac Pacing, Artificial; D017147:Defibrillators, Implantable; D004195:Disease Models, Animal; D004285:Dogs; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D004867:Equipment Design; D006325:Heart Atria / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D010146:Pain / Q000209:etiology / Q000517:prevention & control; D013997:Time Factors; D055536:Vagus Nerve Stimulation