Successful Identification of and Discrimination Between Atrial and Ventricular Arrhythmia with the Aid of Pacing and Defibrillator Devices

The presence of supraventricular tachycardia is the leading cause of inappropriate shock in ICD recipients, and it can be a significant cause of morbidity, psychological distress and worsened clinical outcome. Modern pacing and ICD systems offer a number of discriminators that are integrated into algorithms to differentiate sustained ventricular tachycardia from supraventricular tachycardia. These algorithms can be adapted and optimised for each individual patient to ensure that only those arrhythmias that need treatment through the use of an ICD, are actually treated. This review summarises the single- and dual-chamber discriminators that can be used in the detection and classification of tachyarrhythmias.

Abstract 9764: Prevalence of Inappropriate Defibrillation Attempts During Pediatric In-Hospital Cardiac Arrest

Introduction: Shockable rhythms (ventricular fibrillation [VF] and ventricular tachycardia [VT]) occur in <25% of pediatric in-hospital cardiac arrest (IHCA) events, yet the prevalence of inappropriate defibrillation attempts for non-VF/VT rhythms is unknown. We aim to describe the prevalence of inappropriate shocks across a large, multi-national pediatric cardiac arrest network. Methods: We included children <18y reported to the pedi atric RES uscitation- Q uality (pediRES-Q) network from 2015-2019 with complete defibrillator files who received defibrillation attempts during IHCA (ZOLL R-Series, MA). Two pediatric cardiologists independently classified rhythms immediately prior to shock as: 1) appropriate (VF or wide complex ≥ 150/min), 2) indeterminate (narrow complex ≥150/min or wide complex 100-149/min), or 3) inappropriate (asystole, sinus, narrow complex <150/min, or wide complex <100/min). Rhythms that were undecipherable due to artifact were excluded from analysis (n=22). Disagreements were resolved by arbitration and consensus. Results: Of 896 IHCA events, 124 (14%) had defibrillation attempts. A total of 303 shocks were delivered: 87 (29%) in age <1y, 84 (28%) in 1-8y, and 132 (44%) in 9-17y. Of shocks delivered, 206 (68%) were appropriate, 12 (4%) indeterminate, and 85 (28%) inappropriate. There was no difference in inappropriate shock delivery by age category: <1y (24/87, 28%), 1-8y (26/84, 31%), 9-17y (35/132, 27%) ( p =0.4). Conclusions: Across a multi-national pediatric cardiac arrest network, a large proportion (28%) of defibrillation attempts were inappropriate, suggesting significant opportunity for improvement in rhythm identification in pediatric cardiac arrest. There was no difference in inappropriate shock delivery across age groups. Figure 1. Representation of rhythm classification and appropriateness of defibrillation attempts with exemplar rhythms.

Inappropriate shock delivery by an implantable cardioverter-defibrillator due to electrical interference with a refrigerator in a 4-year-old child

We report a patient with long QT syndrome who received an inappropriate implantable cardioverter-defibrillator shock due to electrical interference from a refrigerator. This electrical interference was mistakenly detected as an episode of ventricular fibrillation and ended with an inappropriate delivery of shock without any warning symptoms before.

Health-related quality of life in patients with implantable cardioverter defibrillators in Sweden: a cross-sectional observational trial

ObjectivesDecisions regarding implantable cardioverter defibrillators (ICDs) must consider information about presumed health-related quality of life (HRQL). The purpose of the study was to assess HRQL in patients with ICD and compare it to a Swedish age-matched and sex-matched population.DesignCross-sectional observational trial.SettingSwedish ICD cohort.InterventionsShort form 36 (SF-36) questionnaires from ICD recipients implanted 2007–2017 (response rate 77.2%) were analysed using Mann-Whitney U test and effect size (ES).ResultsIn total, 223 patients (mean age 71.1±9.7 years, 82.1% men) were included. In most SF-36 domains (physical functioning (PF), role physical, general health (GH), vitality, social functioning and mental health), the score for patients with ICD was significantly lower (ES range 0.23–0.41, ie, small difference) than norms, except for bodily pain and role emotional. Both the physical component summary (PCS) and the mental component summary (MCS) scores had ES=0.31. Men and women had similar scores. Primary and secondary prevention patients scored similarly, except for worse GH in primary prevention (p=0.016, ES=0.35). Atrial fibrillation was associated with worse PF (ES=0.41) and PCS (ES=0.38). Appropriate therapy, inappropriate shock or complications requiring surgery were not associated with lower scores in any domain. In primary prevention due to ischaemic versus non-ischaemic cardiomyopathy, no domain was significantly different. PCS decreased with higher age strata (p=0.002) in contrast to MCS (p=0.986).ConclusionsPatients with ICDs have lower physical and mental HRQL than age-matched and sex-matched norms; however, the ESs are small. HRQL is similar regardless of sex, primary/secondary prevention indication, appropriate therapy, inappropriate shock or complications, but decreases with advancing age.