title: Inappropriate discharges from an intravenous implantable cardioverter defibrillator due to T-wave oversensing.
abstract: This report describes the clinical management of 2 patients with ventricular fibrillation (VF) who received inappropriate shocks from an implantable cardioverter defibrillator (ICD) due to T-wave oversensing. Cardiac sarcoidosis was confirmed as the underlying heart disease in 1 patient and idiopathic dilated cardiomyopathy in the other. Within 2 months after ICD implantation, both patients received several inappropriate shocks during sinus rhythm. Stored electrograms showed decreased R-wave amplitudes and increased T-wave amplitudes. The ICD sensed both R- and T-waves as ventricular activation, which met the rate criteria for VF treatment. Reprogramming the sensing threshold in association with administration of a drug to slow the heart rate decreased the incidence of the inappropriate shocks in both patients, but these palliative measures did not completely suppress the inappropriate shocks. To avoid T-wave oversensing, the repositioning or adding of a sensing lead is required. The potential risk of T-wave oversensing in ICD patients who have small R-wave amplitudes should be recognized.
authors.affiliation: First Department of Internal Medicine, Niigata University Schoool of Medicine, Japan. washi@med.niigata-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Washizuka
authors.forename: M
authors.initials: M
authors.lastname: Chinushi
authors.forename: H
authors.initials: H
authors.lastname: Kasai
authors.forename: H
authors.initials: H
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Tagawa
authors.forename: Y
authors.initials: Y
authors.lastname: Hosaka
authors.forename: A
authors.initials: A
authors.lastname: Abe
authors.forename: Y
authors.initials: Y
authors.lastname: Aizawa
mesh_terms: D000328:Adult; D000368:Aged; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004556:Electric Injuries / Q000209:etiology*; D004562:Electrocardiography; D019544:Equipment Failure Analysis; D004869:Equipment Safety; D005260:Female; D006801:Humans; D014693:Ventricular Fibrillation / Q000150:complications / Q000628:therapy*