title: Phantom shocks unmasked: clinical data and proposed mechanism of memory reactivation of past traumatic shocks in patients with implantable cardioverter defibrillators.
abstract: BACKGROUND
  Implantable cardioverter defibrillators (ICD), despite an unequivocal clinical benefit, are known to have a complex psychosocial impact on the patients. ICD shocks and the resultant psychobiological changes are known to contribute to increased levels of anxiety, depression, and post-shock stress symptoms in these patients. Phantom shock is a patient-reported perception of an ICD shock in the absence of any actual shock; however, its pathophysiological understanding is poor.
  
  
  METHODS
  A retrospective chart review of the University hospital ICD patients' database from June 2006 to April 2010 was conducted. A total of 38 patients with documented phantom shocks as cases and 76 age- and sex-matched patients with no phantom shocks as controls were selected from the database. Patient characteristics were analyzed for their potential association with the occurrence of phantom shocks.
  
  
  RESULTS
  Phantom shock patients had higher prevalence of documented depression (31.6%), anxiety (23.7%), and cocaine use (42.1%). Additionally, patients who had previous ICD shock storms were more likely to have phantom shocks (39.5%; p = 0.001). More importantly, no phantom shocks were reported in patients who did not receive defibrillation threshold testing or past ICD shock storms.
  
  
  CONCLUSIONS
  Phantom shocks are primarily observed in ICD patients who had prior exposure to traumatic device shocks and are more common in patients with a history of depression, anxiety, or substance abuse. A pathophysiological mechanism is proposed as a guide to potential prevention.
authors.affiliation: Division of Cardiology/Electrophysiology, Wayne State University School of Medicine, Detroit, MI, USA. jacobsony@yahoo.com
authors.forename: Sony
authors.initials: S
authors.lastname: Jacob
authors.forename: Sidakpal S
authors.initials: SS
authors.lastname: Panaich
authors.forename: Sandip K
authors.initials: SK
authors.lastname: Zalawadiya
authors.forename: George
authors.initials: G
authors.lastname: McKelvey
authors.forename: George
authors.initials: G
authors.lastname: Abraham
authors.forename: Rajeev
authors.initials: R
authors.lastname: Aravindhakshan
authors.forename: Samuel F
authors.initials: SF
authors.lastname: Sears
authors.forename: Jamie B
authors.initials: JB
authors.lastname: Conti
authors.forename: H Michael
authors.initials: HM
authors.lastname: Marsh
mesh_terms: D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D004556:Electric Injuries / Q000453:epidemiology*; D004868:Equipment Failure / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008824:Michigan / Q000453:epidemiology; D008875:Middle Aged; D012307:Risk Factors