title: An entirely subcutaneous implantable cardioverter-defibrillator.
abstract: BACKGROUND
  Implantable cardioverter-defibrillators (ICDs) prevent sudden death from cardiac causes in selected patients but require the use of transvenous lead systems. To eliminate the need for venous access, we designed and tested an entirely subcutaneous ICD system.
  
  
  METHODS
  First, we conducted two short-term clinical trials to identify a suitable device configuration and assess energy requirements. We evaluated four subcutaneous ICD configurations in 78 patients who were candidates for ICD implantation and subsequently tested the best configuration in 49 additional patients to determine the subcutaneous defibrillation threshold in comparison with that of the standard transvenous ICD. Then we evaluated the long-term use of subcutaneous ICDs in a pilot study, involving 6 patients, which was followed by a trial involving 55 patients.
  
  
  RESULTS
  The best device configuration consisted of a parasternal electrode and a left lateral thoracic pulse generator. This configuration was as effective as a transvenous ICD for terminating induced ventricular fibrillation, albeit with a significantly higher mean (+/-SD) energy requirement (36.6+/-19.8 J vs. 11.1+/-8.5 J). Among patients who received a permanent subcutaneous ICD, ventricular fibrillation was successfully detected in 100% of 137 induced episodes. Induced ventricular fibrillation was converted twice in 58 of 59 patients (98%) with the delivery of 65-J shocks in two consecutive tests. Clinically significant adverse events included two pocket infections and four lead revisions. After a mean of 10+/-1 months, the device had successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia.
  
  
  CONCLUSIONS
  In small, nonrandomized studies, an entirely subcutaneous ICD consistently detected and converted ventricular fibrillation induced during electrophysiological testing. The device also successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia. (ClinicalTrials.gov numbers, NCT00399217 and NCT00853645.)
authors.affiliation: Seattle Institute for Cardiac Research, Seattle, WA, USA. gbardy@sicr.org
authors.forename: Gust H
authors.initials: GH
authors.lastname: Bardy
authors.forename: Warren M
authors.initials: WM
authors.lastname: Smith
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Hood
authors.forename: Ian G
authors.initials: IG
authors.lastname: Crozier
authors.forename: Iain C
authors.initials: IC
authors.lastname: Melton
authors.forename: Luc
authors.initials: L
authors.lastname: Jordaens
authors.forename: Dominic
authors.initials: D
authors.lastname: Theuns
authors.forename: Robert E
authors.initials: RE
authors.lastname: Park
authors.forename: David J
authors.initials: DJ
authors.lastname: Wright
authors.forename: Derek T
authors.initials: DT
authors.lastname: Connelly
authors.forename: Simon P
authors.initials: SP
authors.lastname: Fynn
authors.forename: Francis D
authors.initials: FD
authors.lastname: Murgatroyd
authors.forename: Johannes
authors.initials: J
authors.lastname: Sperzel
authors.forename: Jörg
authors.initials: J
authors.lastname: Neuzner
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Spitzer
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Ardashev
authors.forename: Amo
authors.initials: A
authors.lastname: Oduro
authors.forename: Lucas
authors.initials: L
authors.lastname: Boersma
authors.forename: Alexander H
authors.initials: AH
authors.lastname: Maass
authors.forename: Isabelle C
authors.initials: IC
authors.lastname: Van Gelder
authors.forename: Arthur A
authors.initials: AA
authors.lastname: Wilde
authors.forename: Pascal F
authors.initials: PF
authors.lastname: van Dessel
authors.forename: Reinoud E
authors.initials: RE
authors.lastname: Knops
authors.forename: Craig S
authors.initials: CS
authors.lastname: Barr
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Lupo
authors.forename: Riccardo
authors.initials: R
authors.lastname: Cappato
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Grace
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D004567:Electrodes, Implanted; D004867:Equipment Design; D005260:Female; D006331:Heart Diseases / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D013318:Stroke Volume; D055815:Young Adult