Liesbeth Timmers

Variability in interpretation of the electrocardiogram in young athletes: an unrecognized obstacle for electrocardiogram-based screening protocols.

AIMS To assess in young athletes (i) the variability in the percentage of abnormal electrocardiograms (ECGs) using different criteria and (ii) the variability in ECG interpretation among cardiologists and sport physicians. METHODS AND RESULTS Electrocardiograms of 138 athletes were categorized by seven cardiologists according to the original European Society of Cardiology (ESC) criteria by Corrado (C), subsequently modified by Uberoi (U), Marek (M), and the Seattle criteria (S); seven sports physicians only used S criteria. The percentage of abnormal ECGs for each physician was calculated and the percentage of complete agreement was assessed. For cardiologists, the median percentage of abnormal ECGs was 14% [interquartile range (IQR) 12.5-20%] for C, 11% (IQR 9.5-12.5%) for U [not significant (NS) compared with C], 11% (IQR 10-13%) for M (NS compared with C), and 7% (IQR 5-8%) for S (P < 0.005 compared with C); complete agreement in interpretation was 64.5% for C, 76% for U (P < 0.05 compared with C), 74% for M (NS compared with C), and 84% for S (P < 0.0005 compared with C). Sport physicians classified a median of 7% (IQR 7-11%) of ECGs as abnormal by S (P = NS compared with cardiologists using S); complete agreement was 72% (P < 0.05 compared with cardiologists using S). CONCLUSION Seattle criteria reduced the number of abnormal ECGs in athletes and increased agreement in classification. However, variability in ECG interpretation by cardiologists and sport physicians remains high and is a limitation for ECG-based screening programs.

Undersensing by an ICD due to alternans of the ventricular electrogram

Alternans of the ventricular electrogram (VEGM) during ventricular tachycardia (VT) is a rare cause of ventricular undersensing by an implantable cardioverter‐defibrillator (ICD). This report describes a patient with a St. Jude ICD who exhibited sustained monomorphic VT associated with surface QRS alternans, alternating cycle lengths, alternans of the VEGM causing intermittent undersensing of the smaller component, and intermittent 2:1 counting of ventricular intervals during 1:1 sensing in response to the ICD detection algorithm. VEGM undersensing was corrected noninvasively simply by programming the threshold start from 62.5% to 50% which increased the sensitivity based on the amplitude of the VEGM. This maneuver did not affect the satisfactory and stable defibrillation threshold.

Clinical assessment and comparison of annotation algorithms in high-density mapping of regular atrial tachycardias

High‐density automated mapping of regular atrial tachycardias (ATs) requires accurate assessment of local activation times (LATs).

A “Shocking” Case Rectified

A 29-year-old man received a Lumax 340 VRT XL implantable cardioverter defibrillator (ICD) connected to a Linox S 65 single-coil true bipolar shock lead (BIOTRONIK SE &CO, KG, Berlin, Germany) in 2008 after successful resuscitation from sustained ventricular tachycardia (VT). An underlying Brugada syndrome (BS) was diagnosed. At implant R-wave sensing was 12.5 mV. Tachycardia detection was programmed as follows: VT monitoring zone between 180 beats/min and 240 beats/min and ventricular fibrillation (VF) zone for rates above 240 beats/min. VF induction was performed and showed correct sensing at least sensitivity. The patient remained asymptomatic until November 2012 when he experienced an ICD shock during strenuous exercise (Fig. 1). Is this an appropriate or inappropriate shock and what is the cause of the shock?

Automated verification of pulmonary vein isolation in radiofrequency- and cryoballoon-guided ablation: DE POOTER et al .

Verification of pulmonary vein isolation (PVI) can be challenging due to the coexistence of pulmonary vein potentials and far‐field potentials. This study aimed to prospectively validate a novel algorithm for automated verification of PVI in radiofrequency (RF)‐guided and cryoballoon (CB)‐guided ablation strategies.

Evaluating current implantable cardioverter defibrillator implantation procedures: can common complications be minimised?

ABSTRACT The implantable cardioverter-defibrillator (ICD) is the cornerstone of treatment and prevention of malignant ventricular arrhythmias. Despite 30 years of experience, implantation of ICDs carries a risk of complications both during the procedure and long-term follow-up. Operator and procedure related factors may contribute to this risk. Furthermore, access, pocket, device and lead related problems occur, on top of problems related to arrhythmias and the patient themselves. Infection is the most feared complication, and its incidence seems to rise. Factors leading to complications are assessed, as well as measures to reduce these complications, including antibiotics and subcutaneous devices. Four patient categories with an increased risk are identified: the elderly with atrial fibrillation, diabetes or renal failure; the pediatric patient with or without congenital heart disease, the young patient with specific inherited diseases, and all those who undergo replacement, upgrade or concomitant lead extraction.

Unusual Cause of Far-Field Atrial Sensing by the Ventricular Lead of a Dual Chamber Defibrillator. What is the Mechanism?

A Biotronik Lexos dual chamber implantable cardioverter-defibrillator (ICD; Biotronik GmbH, Berlin, Germany)1 was implanted with a dedicated bipolar lead in a patient with severe dilated cardiomyopathy. Ventricular oversensing of farfield atrial signals occurred several days after implantation. Pacing and shock impedances were normal. The atrial electrogram was unremarkable but the ventricular electrogram revealed an obvious deflection coincident with atrial activity (double counting; Fig. 1).