Abstract 15917: Low-Energy Three-Stage Electrotherapy Delivered Through Endocardial Leads Terminates Ventricular Tachycardia With Higher Efficacy Than Anti-Tachycardia Pacing
INTRODUCTION: Current implantable defibrillators use a high-energy biphasic (BP) shock to terminate VT when anti-tachycardia pacing (ATP) fails. Previously, we showed that multiple monophasic (MP) shocks terminate monomorphic ventricular tachycardia (VT) with less total energy compared to a single monophasic shock in a canine myocardial infarction (MI) model. In this study, we compared a novel Three-Stage electrotherapy (3ST) to a single biphasic shock (1BP), delivered via a fully endocardial lead system.
METHODS: MI was induced in mongrel dogs (n=3). Four days later, endocardial bipolar pace/shock leads were placed in the right ventricle (RV) apex and coronary sinus (CS). A patch (LVP) was placed over the posterolateral left ventricle. ATP [8 pulses, 88% of the VT cycle length (CL)] was attempted via the RV bipole after sustained VT induction. If ATP failed, cardioversion thresholds (CVT) of 3ST and 1BP were measured. 3ST consisted of 3 sequential stages: 3 MP shocks delivered within 1 VT CL, 6 MP shocks delivered with an interval of 88% of the VT CL at the ventricular capture voltage, and ATP. RV-CS coil and RV-LVP shock vectors were compared.
RESULTS: The average CL of sustained VT was 148 ± 26 ms. The success rate of ATP was 7.04%. The RV-CS shock vector had lower impedance than RV-LVP (54.4 ± 18.1 Ohms versus 109.8 ± 16.9 Ohms, respectively, p < 0.001). 3ST delivered from the RV-CS vector significantly reduced the CVT compared to 1BP with respect to total energy (0.03 ± 0.05 J versus 2.37 ± 1.20 J, respectively, p < 0.001) and peak shock voltage (7.2 ± 6.9 V versus 137.7 ± 43.8 V, respectively, p < 0.001).
CONCLUSIONS: Three-Stage electrotherapy terminates ATP-resistant VT with significantly lower peak voltage and total energy compared to a conventional single biphasic shock. This novel electrotherapy is a low-voltage, low-energy alternative to high-energy ICD shocks when ATP fails, and can be delivered through a fully implantable endocardial lead system.
- Arrhythmias, treatment of
- Ventricular tachycardia
- Myocardial infarction
- Ventricular defibrillation
- © 2011 by American Heart Association, Inc.