Abstract 15009: Extra-Low Energy Defibrillation With Epicardial Implantable Cardioverter Defibrillator Networks With Electrically Conductive Fibers in Disease Models

Abstract

Introduction: We previously reported that extra-low energy (<0.6J) defibrillation is possible with the epicardial ICD net lead system (Ep-ICD) in normal canine hearts. Hypothesis: The aim of this study was to test whether the Ep-ICD can terminate ventricular fibrillation (Vf) with the same energy in two disease models (heart failure and long QT syndrome (LQT)). Methods: 1. Ep-ICD was constructed by fine tungsten fibers at the top and bottom of the cardiac mesh (Figure 1), connected to the RV and SVC coils of the DF-1 lead, respectively. 2. Heart failure was induced by rapid right ventricular pacing (170 bpm, 8 weeks). 3. Vf was induced by placing a 9V battery on the surface of the heart. DC shock was delivered with a minimum energy of 0.4J (Medtronic Viva XT). 4. Defibrillation threshold (DFT) was defined as 75% of defibrillation success. 5. LQT was simulated by reducing the conductance (Gk) of the IKS current by (x 1.0(CTL) or 0.8(LQT)) by computer simulation. Results: 1. DFT(J) of Ep-ICD in the canine HF model: 0.8, 1.2, 1.2. 3, Minimum DF energy(J): 0.6, 0.6, 0.8, 2. Maximum DF energy(J): 1.2, 1.6, 5, 52. Immediate return to sinus rhythm (SR) was achieved in most cases after DC delivery. In a small number of cases, brief periods of VT occurred, with rapid return to SR. No tachycardic arrhythmias occurred after return to SR. 3. The DFT was 0.39 for LQT and 0.52 for CTL. Conclusions: 1. DFT of Ep-ICD increased from 0.6 J in normal canine heart to 1.2 J in canine HF model, but still much lower energy used in current ICD system (36 J). 2. The Ep-ICD lead system is the least traumatic and still within the acceptable range while conscious. 3. DFT of LQT with Ep-ICD is 25% lower than normal heart. 4. Ultra-low energy DC can avoid conduction abnormalities or malignant arrhythmias after shock. Hearts return to SR immediately. 5. Ep-ICD can deliver the DC shock before loss of consciousness, improving quality of life and safety of ICD therapy.