title: Clinical results of far-field R-wave reduction with a short tip-ring electrode.
abstract: BACKGROUND
  Far-field R-wave (FFRW) sensing of the atrial lead of AAI or DDD pacemakers causes incorrect mode switches and remains a problem in patients with atrial arrhythmias in whom low voltage sensing is essential. We studied a pacing electrode with a short tip-ring distance (1.1 mm). We compared our findings with recordings from a conventional electrode with a larger tip-ring distance (10 mm).
  
  
  METHODS
  Thirty-six consecutive patients with an indication for DDD pacing were implanted with the short tip-ring electrode. Another 23 patients received the conventional electrode. FFRW and P-wave amplitudes during pacing and intrinsic ventricular depolarization were measured at implantation. Measurements were repeated before hospital discharge and at follow-up between 10 and 14 days after implantation.
  
  
  RESULTS
  P-wave amplitude was slightly smaller in the short tip-ring group (2.71+/-1.04 vs 3.17+/-1.30 mV in the conventional group, respectively, P=NS). All P-waves exceeded 1.2 mV. FFRW during pacing was 0.07+/-0.05 in the short tip-ring group and 0.54+/-0.32 mV in the conventional group (P<0.001). FFRW during intrinsic rhythm was 0.08+/-0.04 and 0.55+/-0.31 mV, respectively (P<0.001). The ratio between P-wave and FFRW was 48.6+/-27.2 in the short tip-ring group and 7.3+/-4.4 in the conventional group (P<0.001). FFRW and P-wave amplitudes did not change at hospital discharge or during follow-up.
  
  
  CONCLUSIONS
  FFRW can be suppressed without compromising P-wave sensing by using a pacing electrode with a short tip-ring distance. Whether reduced FFRW amplitude results in clinical endpoints remains to be determined.
authors.affiliation: St. Lucas Andreas Hospital, Department of Cardiology, Amsterdam, The Netherlands.
authors.forename: Joris R
authors.initials: JR
authors.lastname: De Groot
authors.forename: Jutta M
authors.initials: JM
authors.lastname: Schroeder-Tanka
authors.forename: Jaap
authors.initials: J
authors.lastname: Visser
authors.forename: Albert R
authors.initials: AR
authors.lastname: Willems
authors.forename: Willem G
authors.initials: WG
authors.lastname: De Voogt
mesh_terms: D016477:Artifacts; D002304:Cardiac Pacing, Artificial / Q000379:methods; D004562:Electrocardiography / Q000295:instrumentation*; D004567:Electrodes, Implanted; D004867:Equipment Design; D004868:Equipment Failure; D019544:Equipment Failure Analysis; D006801:Humans; D010138:Pacemaker, Artificial; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity