title: Do daily threshold trend fluctuations of epicardial leads correlate with pacing and sensing characteristics in paediatric patients?
abstract: OBJECTIVE
  To evaluate whether the magnitude of daily ventricular pacing threshold fluctuations (Deltafluctuation) in trend graphs of stored diagrams correlate with ventricular threshold and sensing changes over time.
  
  
  RESULTS
  A total of 56 children received AutoCapture devices (St. Jude Medical, Sylmar, CA, USA) connected to steroid-eluting epicardial leads. Maximum lead age at study closure was 12.2 years (median 4.0). Telemetry data and daily Deltafluctuation were obtained every 6 months. Regression slope coefficients and mean values of repeated measurements were calculated for each patient's course. High daily Deltafluctuation correlated with higher pacing thresholds (rho = 0.68, P < 0.001), lower impedances (rho = -0.38, P = 0.004), and a Deltafluctuation-incline (rho = 0.34, P = 0.01) over time. Furthermore, a Deltafluctuation-incline correlated with a pacing threshold-incline (rho = 0.34, P = 0.01). No correlation was observed for ventricular sensing. Higher daily Deltafluctuation were observed if lead age was > 5 years compared with <or= 5 years (0.75 vs. 0.55 V@0.5 ms, P = 0.028).
  
  
  CONCLUSIONS
  High amplitudes of daily Deltafluctuation correlate with higher and increasing pacing thresholds and lower impedances. Theoretically, this results from electrode microinstability on the epicardial surface. A decrease of the steroid-eluting potency of the electrode can be hypothesized to cause higher daily Deltafluctuation beyond a lead age of 5 years. Potential implications of marked daily Deltafluctuation are short-term follow-up and lead replacement in the presence of high pacing thresholds.
authors.affiliation: Division of Pediatric Cardiology, University Children's Hospital, Steinwiesstrasse 75, 8032 Zurich, Switzerland. maren.tomaske@kispi.unizh.ch
authors.forename: Maren
authors.initials: M
authors.lastname: Tomaske
authors.forename: Paul
authors.initials: P
authors.lastname: Harpes
authors.forename: Ali
authors.initials: A
authors.lastname: Dodge-Khatami
authors.forename: Nadja
authors.initials: N
authors.lastname: Amacker
authors.forename: Urs
authors.initials: U
authors.lastname: Bauersfeld
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D004056:Differential Threshold; D004562:Electrocardiography / Q000379:methods*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008297:Male; D010496:Pericardium; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013813:Therapy, Computer-Assisted / Q000379:methods*; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000517:prevention & control*