Abstract 16129: Low-Energy Three-Stage Electrotherapy Delivered Through Implantable Leads Significantly Reduces the Cardioversion Threshold in a Canine Model of Persistent Atrial Fibrillation
BACKGROUND: Previous attempts to apply implantable defibrillation therapy to atrial fibrillation (AF) were severely limited by the pain associated with high-energy biphasic (BP) shocks. Recently, we showed that a sequential three-stage (3-Stage) electrotherapy may significantly reduce the atrial defibrillation threshold (DFT) in an open chest, canine model of acute AF. In this study, we implanted a transvenous endocardial lead system to deliver this 3-stage therapy in a closed chest canine model of persistent AF. We aimed to assess the feasibility of potentially painless defibrillation of AF through an implantable device/lead system.
METHODS: Bipolar pace/shock leads were implanted in the right atrium (RA) and left pulmonary artery (LPA), reproducing RA to distal coronary sinus vector, in mongrel dogs (N=4). Persistent AF was induced by high rate atrial pacing for 8-12 weeks. The atrial DFTs of 3-Stage therapy and a single BP shock (1BP) delivered through the RA-LPA vector were measured. 3-Stage therapy consisted of 3 sequential stages: 2 BP shocks delivered within 1 AF cycle length (CL), 6 MP shocks delivered at an interval of 88% of the AF CL at 50% of the ventricular capture voltage, and anti-tachycardia pacing (ATP; 8 pulses with an interval 88% of the AF CL) delivered through the RA bipole.
RESULTS: The mean cycle length of AF was 115 ± 17 ms. The impedance of the RA-LPA vector was 103.1 ± 15.7 Ohms. 3-Stage therapy significantly decreased the atrial DFT compared to a single biphasic shock with respect to total energy (0.27 ± 0.14 J versus 1.45 ± 0.36 J; p < 0.001) and peak voltage (42.3 ± 14.8 V versus 161.2 ± 18.7 V, p < 0.001).
CONCLUSIONS: 3-Stage electrotherapy terminates persistent AF with significantly lower peak voltage and lower total energy compared to a conventional single biphasic shock. This therapy was delivered through a transvenously implanted lead system, and thus may allow for new device-based therapy for potentially painless low-energy atrial defibrillation.
- Arrhythmias, treatment of
- Atrial defibrillation
- Atrial fibrillation
- Implantable cardioconvert defibrillator
- New technology
- © 2011 by American Heart Association, Inc.