title: Automatic capture verification in ICD lead systems using intracardiac ventricular evoked response and reduced coupling capacitance.
abstract: OBJECTIVE
  Intracardiac ventricular evoked-response (ER) signals detected by implanted cardioverter defibrillator (ICD) lead systems were investigated for automatic capture verification (AC).
  
  
  METHODS
  ER signals were evaluated with an external pacing system equipped with a reduced coupling capacitance (CC=2.2 microF) 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.
authors.affiliation: Kerckhoff-Klinik, Department of Cardiology and Electrophysiology, Benekestrasse 2-8, 61231, Bad Nauheim, Germany. Johannes.Sperzel@kerckhoff.med.uni-giessen.de
authors.forename: J
authors.initials: J
authors.lastname: Sperzel
authors.forename: H F
authors.initials: HF
authors.lastname: Pitschner
authors.forename: T
authors.initials: T
authors.lastname: Schwarz
authors.forename: A
authors.initials: A
authors.lastname: König
authors.forename: Q
authors.initials: Q
authors.lastname: Zhu
authors.forename: J
authors.initials: J
authors.lastname: Neuzner
mesh_terms: D002304:Cardiac Pacing, Artificial; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D004567:Electrodes, Implanted; D005071:Evoked Potentials; D006801:Humans; D008875:Middle Aged