Autonomic capture verification in ICD lead systems using intracardiac ventricular evoked response and reduced coupling capacitance

Abstract

Aim. Intracardiac ventricular evoked-response (ER) signals detected by implanted cardioverter defibrillator (ICD) lead systems were investigated for automatic capture verification (AC). Method. ER signals were evaluated with an external pacing system equipped with a reduced coupling capacitance (CC=2.2 μF) in the pacing output circuit during ventricular step-down threshold testing at 0.4 ms pulse duration. Real-time pacing markers, surface ECG and intracardiac electrograms pre- and post-filtering were digitally recorded. Results. Twenty consecutive patients, age 61 ± 12 years, with leads from two different manufacturers were tested - 10 were implanted with acute leads (AL) and 10 with chronic leads (CL). The analysis was based on the ER amplitude during capture and on the ER-to-afterpotential ratio (SAR), with SAR>2 as the criterion for successful capture detection. ER amplitudes (median and range) were 8.1 mV (2.1-19.5 mV) for AL and 8.3 mV (3.7-14.2 mV) for CL. SAR values (median and range) were 48.0 (2.5-682.6) for AL and 13.2 (6.3-35.9) for CL, indicating that AC could successfully be applied in all patients. Conclusions. Reducing the pacing CC allows adequate ER detection for automatic capture verification on non-selected ICD lead systems. The effect of high-voltage shock treatment on ER signal detection requires further investigation. © 2003 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.