title: An unusual mechanism causing inappropriate implantable cardioverter defibrillator shocks: transient reduction in R-wave amplitude.
abstract: Inappropriate shocks delivered by the implantable cardioverter defibrillator (ICD) are an increasingly recognized complication. The most frequent cause is related to supraventricular rhythms associated with fast conduction to the ventricles that are incorrectly detected as ventricular tachycardia leading to inappropriate antitachycardia pacing and/or shocks. Oversensing is a frequent cause of inappropriate shocks usually due to increased amplitude of the T-wave secondary to ischaemia or electrolyte disorders that lead to T-wave double counting. We describe an unusual case of T-wave double counting during sinus rhythm caused by transient reduction in R-wave amplitude with no changes in T-wave amplitude resulting in inappropriate shocks.
authors.affiliation: Arrhythmia Service, McMaster University, Hamilton Health Sciences Corporation, Hamilton, Ontario, Canada. barancha@kgh.kari.net
authors.forename: Adrian
authors.initials: A
authors.lastname: Baranchuk
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ribas
authors.forename: Syamkumar
authors.initials: S
authors.lastname: Divakaramenon
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Morillo
mesh_terms: D000368:Aged; D005117:Cardiac Complexes, Premature / Q000209:etiology* / Q000517:prevention & control*; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004868:Equipment Failure; D019544:Equipment Failure Analysis; D006801:Humans; D008297:Male