title: Sensing failure associated with the Medtronic Sprint Fidelis defibrillator lead.
abstract: BACKGROUND
  The diameter of implantable cardioverter-defibrillator (ICD) leads has become progressively smaller over time. However, the long-term performance characteristics of these smaller ICD leads are unknown.
  
  
  METHODS
  We retrospectively evaluated 357 patients who underwent implantation of a Medtronic Sprint Fidelis defibrillating lead at two separate centers between September 2004 and October 2006. Lead characteristics were measured at implant, at early follow-up (1-4 days post implant), and every 3-6 months thereafter.
  
  
  RESULTS
  During the study period, 357 patients underwent implantation of the Medtronic Sprint Fidelis lead. The mean R-wave measured at implant through the device was not different (P = NS) when compared with that measured at first follow-up (10.5 +/- 5.0 mV vs 10.7 +/- 5.1 mV). Forty-one patients (13%) had an R-wave amplitude <or= 5 mV measured through the device at implant. Of those patients with an R-wave amplitude <or= 5 mV at implant measured through the device, 63% (n = 26) remained <or= 5 mV for the duration of follow-up. The mean time to R-wave amplitude <or= 5 mV was 96.2 +/- 123 days. During follow-up, 65 (18%) patients developed R-wave <or= 5 mV. Overall 10 lead revisions (2.8%) were performed during the first year of follow-up.
  
  
  CONCLUSIONS
  Abnormal R-wave sensing is frequently observed during follow-up with the Medtronic Fidelis ICD lead. Lead revision was necessary in 2.8% of the patients, most often (8 of 10) due to abnormal R-wave sensing along with elevated pacing threshold. Whether this issue is limited to this lead or reflects a potential problem with all downsized ICD leads merits further investigation.
authors.affiliation: Virginia Commonwealth University Medical Center, Richmond, Virginia 23298-0053, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Kenigsberg
authors.forename: Sunil
authors.initials: S
authors.lastname: Mirchandani
authors.forename: Amanda N
authors.initials: AN
authors.lastname: Dover
authors.forename: Marcin
authors.initials: M
authors.lastname: Kowalski
authors.forename: Mark A
authors.initials: MA
authors.lastname: Wood
authors.forename: Richard K
authors.initials: RK
authors.lastname: Shepard
authors.forename: Gautham
authors.initials: G
authors.lastname: Kalahasty
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Stein
authors.forename: Steven M
authors.initials: SM
authors.lastname: Markowitz
authors.forename: Sei
authors.initials: S
authors.lastname: Iwai
authors.forename: Bindi K
authors.initials: BK
authors.lastname: Shah
authors.forename: Bruce B
authors.initials: BB
authors.lastname: Lerman
authors.forename: Suneet
authors.initials: S
authors.lastname: Mittal
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Ellenbogen
mesh_terms: D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D004562:Electrocardiography / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data*; D004567:Electrodes, Implanted / Q000706:statistics & numerical data*; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014481:United States / Q000453:epidemiology