Temporal-component analysis of diastolic electrograms in ventricular tachycardia differentiates nonvulnerable regions of the circuit.

Background: Successful activation mapping of ventricular tachycardia (VT) is dependent on the identification of a region of diastolic conduction by use of point-by-point sequential mapping. It is important to identify the site of transition from diastolic conduction to systolic activation of healthy myocardium (exit site) and differentiate this from nonvulnerable regions of the circuit.

Objective: We sought to determine the temporal and component characteristics of exit-site electrograms using simultaneous multielectrode endocardial mapping and to differentiate them from bystander sites during activation mapping.

Radiographic predictors of lead conductor fracture.

Background: Lead fracture is a limiting factor in high voltage lead durability. Fractures noted with the Medtronic Fidelis leads provide an opportunity to examine factors captured on implant chest x-ray that correlate with risk for lead conductor fracture. We evaluated contributory factors in a large population of fractures.

Uncovering phantom shocks in cardiac patients with an implantable cardioverter defibrillator.

Background: Implantable cardioverter defibrillator recipients sometimes report "phantom shocks" (PSs), defined as a reported shock lacking objective evidence. The aim of this study was to describe the subjective experience of PSs and their psychosocial correlates using a mixed methods approach.

Methods: PS participants were matched on sex and age with individuals who received objective shocks only (OSO).

Failure rate of the Riata lead under advisory: a report from the CHRS Device Committee.

Background: A unique form of lead failure has been described in the Riata (8-F) and Riata ST (7-F) silicone defibrillation lead degradation of the outer insulation, resulting in the externalization of conductor cables.

Objective: To assess rates of lead revision due to lead failure in Riata leads affected by the Riata advisory.

Methods: Nineteen implantable cardioverter-defibrillator implant and follow-up centers were surveyed.

A randomized controlled trial of cognitive behavior therapy tailored to psychological adaptation to an implantable cardioverter defibrillator.

Objectives: To evaluate a eight-session cognitive behavior therapy (CBT) intervention tailored to adaptation in implantable cardioverter defibrillator (ICD) patients; and to test for treatment group by gender interaction effects.

Methods: Patients receiving their first ICD implant were randomized to CBT or usual cardiac care. Primary outcomes measured at baseline, 6-month, and 12-month follow-ups were symptoms of anxiety and depression (Hospital Anxiety and Depression Scale), posttraumatic stress disorder symptoms (Impact of Events Scale-Revised), and phobic anxiety (Crown-Crisp Experiential Index).

Complications associated with revision of Sprint Fidelis leads: report from the Canadian Heart Rhythm Society Device Advisory Committee.

Background: It has been observed that replacement of an implantable cardioverter-defibrillator generator in response to a device advisory may be associated with a substantial rate of complications, including death. The risk of lead revision in response to a lead advisory has not been determined previously.

Methods And Results: Twenty-five implantable cardioverter-defibrillator implantation and follow-up centers from the Canadian Heart Rhythm Society Device Advisory Committee were surveyed to assess complication rates as a result of lead revisions due to the Sprint Fidelis advisory issued in October 2007.

Formation of a national network for rapid response to device and lead advisories: The Canadian Heart Rhythm Society Device Advisory Committee.

The Canadian Heart Rhythm Society (CHRS) Device Advisory Committee was commissioned to respond to advisories regarding cardiac rhythm device and lead performance on behalf of the CHRS. In the event of an advisory, the Chair uses an e-mail network to disseminate advisory information to Committee members broadly representative of the Canadian device community. A consensus recommendation is prepared by the Committee and made available to all Canadian centres on the CHRS Web site after approval by the CHRS executive.

Utilization of a national network for rapid response to the Medtronic Fidelis lead advisory: the Canadian Heart Rhythm Society Device Advisory Committee.

Background/objective: The Canadian Heart Rhythm Society (CHRS) Device Advisory Committee was commissioned in 2006 to develop a mechanism for responding to advisories regarding cardiac rhythm device and lead performance.

Methods: In the event of an advisory, the Chair classifies the advisory as urgent, semi-urgent, or routine based on the nature of the threat to the patient and the number of patients affected. The Chair uses an e-mail network with the committee members to disseminate advisory information and to assemble a consensus recommendation.

Outcome of advisory implantable cardioverter-defibrillator replacement: one-year follow-up.

Background: Implantable cardioverter defibrillator (ICD) generator advisories present management dilemmas for physicians regarding competing risks of ICD failure and replacement-related complications. There is currently a paucity of long-term data concerning the complications associated with advisory ICD replacement.

Objective: In a large multicenter advisory ICD generator replacement cohort followed for 12 months, we aimed to assess replacement-related complications by performing a case-control determination of complication risk factors to identify characteristics that could assist with advisory ICD replacement decision making.

Outcome of the Fidelis implantable cardioverter-defibrillator lead advisory: a report from the Canadian Heart Rhythm Society Device Advisory Committee.

Background: The Medtronic Sprint Fidelis family of leads has recently been the subject of a widespread advisory. Lead failure rates are estimated at 2.3% at 30 months, 2.

A case of appropriate inappropriate device therapy: hyperkalemia-induced ventricular oversensing.

The present case describes a patient who received inappropriate, but potentially life-saving, therapy from her implantable cardioverter defibrillator (ICD) in the setting of acute hyperkalemia (plasma potassium concentration = 8 mM). Hyperkalemia was associated with the development of a slow sinusoidal ventricular tachycardia, at a rate of 100 beats/min to 125 beats/min (610 ms to 480 ms) in a patient who is pacemaker-dependent. There was associated fractionation of the ICD electrogram and T wave oversensing, leading to ventricular oversensing with resultant detection in the ventricular fibrillation rate zone.

Use of implantable cardioverter defibrillators after out-of-hospital cardiac arrest: a prospective follow-up study.

Background: Survivors of out-of-hospital cardiac arrest are at high risk of recurrent arrests, many of which could be prevented with implantable cardioverter defibrillators (ICDs). We sought to determine the ICD insertion rate among survivors of out-of-hospital cardiac arrest and to determine factors associated with ICD implantation.

Methods: The Ontario Prehospital Advanced Life Support (OPALS) study is a prospective, multiphase, before-after study assessing the effectiveness of prehospital interventions for people experiencing cardiac arrest, trauma or respiratory arrest in 19 Ontario communities.