title: Fluoroscopic and electrical assessment of a series of defibrillation leads: prevalence of externalized conductors.
abstract: BACKGROUND
  Insulation defects with externalized conductors have been reported in the St. Jude Riata(®)  family of defibrillation leads (St. Jude Medical, Sylmar, CA, USA). The objective of the Northern Ireland Riata(®)  lead screening program was to identify insulation defects and externalized conductors by systematic fluoroscopic and electrical assessment in a prospectively defined cohort of patients. We sought to estimate the prevalence, identify risk factors, and determine the natural history of this abnormality.
  
  
  METHODS
  All patients with a Riata(®)  lead under follow-up at the Royal Victoria Hospital were invited for fluoroscopic imaging and implantable cardioverter-defibrillator lead parameter checks. Fluoroscopic images were read independently by two cardiologists and the presence of externalized conductors was classified as positive, negative, or borderline.
  
  
  RESULTS
  One hundred and sixty-five of 212 patients with a Riata lead were evaluated by fluoroscopy and lead parameter measurements. The mean duration after implantation was 3.98+/-1.43 years. After screening 25 (15%) patients were classified as positive, 137 (83%) negative, and three (1.8%) borderline. Time since implantation (P = 0.001), presence of a single coil lead (P = 0.042), and patient age (P = 0.034) were significantly associated with externalized conductors. The observed rate of externalized conductors was 26.9% for 8-French and 4.7% for 7-French leads. No leads that were identified prospectively with externalized conductors had electrical abnormalities. Seven of 25 (28%) patients had a defective lead extracted by the end of this screening period.
  
  
  CONCLUSIONS
  A significant proportion (15%) of patients with a Riata lead had an insulation breach 4 years after implantation. High-resolution fluoroscopic imaging in at least two orthogonal views is required to identify this abnormality.
authors.affiliation: Cardiology Department, Royal Victoria Hospital, Belfast, Northern Ireland, United Kingdom. vivek.kodoth@belfasttrust.hscni.net
authors.forename: Vivek N
authors.initials: VN
authors.lastname: Kodoth
authors.forename: Emily C
authors.initials: EC
authors.lastname: Hodkinson
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Noad
authors.forename: Kyle P
authors.initials: KP
authors.lastname: Ashfield
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Cromie
authors.forename: David J
authors.initials: DJ
authors.lastname: McEneaney
authors.forename: Carol M
authors.initials: CM
authors.lastname: Wilson
authors.forename: Michael J D
authors.initials: MJ
authors.lastname: Roberts
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004567:Electrodes, Implanted; D004867:Equipment Design; D004868:Equipment Failure / Q000706:statistics & numerical data*; D019544:Equipment Failure Analysis; D004869:Equipment Safety; D005260:Female; D005471:Fluoroscopy / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged