The role of Purkinje fibers in the emergence of an incessant form of polymorphic ventricular tachycardia or ventricular fibrillation associated with ischemic heart disease

Background: The clinical and electrophysiological characteristic of ventricular premature contractions (VPCs) which trigger the incessant form of polymorphic ventricular tachycardia (VT), so-called “electrical storm” associated with ischemic heart disease, remains unclarified. The aim of this study was to evaluate those matters and the possible role of the Purkinje network in the emergence of an electrical storm. Methods and results: We experienced 5 patients (68 ± 5 years, mean LVEF: 29%) with electrical storms which occurred during the acute phase of an infarction in 3 patients and the remote phase in 2. The triggering VPCs were multifocal in 3 patients and monofocal in the remaining 2. Radiofrequency (RF) catheter ablation was performed for a goal of eliminating the triggering VPCs. A total of 9 different kinds of VPCs differentiated by their morphology were successfully eliminated by the RF deliveries targeting the VPCs’ foci. At the successful ablation sites, Purkinje potentials preceded the QRS onset of the VPC by 67 ± 23 ms, suggesting the VPCs originated in the surviving Purkinje fibers. Moreover, the extensive RF deliveries applied at the surviving Purkinje network rendered the polymorphic VT unable to be induced by programmed stimulation which reproducibly induced it before the ablation in 2 patients. Conclusion: A surviving Purkinje network might contribute not only to the initiation of the repetitive form of lethal ventricular arrhythmias, but also to the perpetuation of the arrhythmias in patients with ischemic heart disease

Frequency analysis of surface electrocardiograms (ECGs) in patients with persistent atrial fibrillation: Correlation with the intracardiac ECGs and implications for radiofrequency catheter ablation

Background: The nature and significance of the frequency characteristics of the surface electrocardiogram (ECG) in patients with persistent atrial fibrillation (AF) undergoing radiofrequency ablation are unclear. Methods: Preablation surface and intracardiac ECGs were obtained using offline fast Fourier transform (FFT) analysis in 40 patients with persistent AF. For the FFT analysis of the surface f-wave, the QRS-T complex was canceled utilizing a template subtraction algorithm. The ablation procedure included isolation of the pulmonary veins (PV) and posterior left atrium and linear ablation of the mitral isthmus and additional lesions using a stepwise approach. Results: The dominant frequency (DF) of all the intracardiac signals, except for the left inferior PV, had a significant correlation with the DFs from the surface electrocardiogram. The strongest correlation was observed between the DFs of the left atrial appendage (LAA) and those on the limb leads (correlation coefficient, 0.802–0.882, P<0.001) and between the DFs on the right atrial appendage and those on lead V1 (correlation coefficient, 0.86, P<0.0001). After radiofrequency ablation, AF was terminated in 23 patients and persisted in the remaining 17. The best electrographic predictor of AF termination was the DFs in the LAA (DF<6.5 Hz, sensitivity 75%, specificity 86%) and lead II (DF<5.9 Hz, sensitivity 82%, specificity 78%), respectively. Conclusions: The frequency characteristics of the surface ECG correlated with those of the intracardiac signals, and the DF predicted termination of AF during radiofrequency ablation in patients with persistent AF

Efficacy of Electroanatomical Mapping for Radiofrequency Ablation of Right-sided Accessory Pathways

Introduction: Due to the difficulty in performing detailed mapping around the tricuspid annulus and the high occurrence of mechanical trauma during the procedure, the outcome of right-sided accessory pathway (AP) ablation still has a relatively high primary failure and recurrence rate. Methods and Results: Six patients with right free-wall APs underwent electroanatomical mapping. The AP had retrograde unidirectional conduction in 3 patients, anterograde unidirectional conduction in 1 patient, and bidirectional conduction in 2 patients. The right atrial (RA) activation map was constructed during right ventricular (RV) pacing (n = 5), and the RV activation map was constructed during RA pacing (n = 3). During mapping, the AP conduction was interrupted by catheter mechanical trauma in 3 patients. The first RF application successfully eliminated the AP conduction within 2 seconds in 3 patients with concealed pathways. In the remaining 3 patients, rescue RF energy was delivered at the tagged bump site on the map. The mean procedure time was 214 ± 77 minutes, and mean fluoroscopy time 63 ± 23 minutes. No recurrence occurred during 12 ± 3.2 months of followup in any of the patients. Conclusions: With the guidance of an electroanatomical mapping system, right-sided accessory pathways can be satisfactorily eliminated without later recurrence

Search for supersymmetry in events with large missing transverse momentum, jets, and at least one tau lepton in 20 fb−1 of √s= 8 TeV proton-proton collision data with the ATLAS detector

© 2014, The Author(s). A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, at least one hadronically decaying tau lepton and zero or one additional light leptons (electron/muon), has been performed using 20.3fb−1of proton-proton collision data at √ s= 8 TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed in the various signal regions and 95% confidence level upper limits on the visible cross section for new phenomena are set. The results of the analysis are interpreted in several SUSY scenarios, significantly extending previous limits obtained in the same final states. In the framework of minimal gauge-mediated SUSY breaking models, values of the SUSY breaking scale Λ below 63 TeV are excluded, independently of tan β. Exclusion limits are also derived for an mSUGRA/CMSSM model, in both the R-parity-conserving and R-parity-violating case. A further interpretation is presented in a framework of natural gauge mediation, in which the gluino is assumed to be the only light coloured sparticle and gluino masses below 1090 GeV are excluded