Electrical Storms in Brugada Syndrome: Review of Pharmacologic and Ablative Therapeutic Options

Electrical storm occurring in a patient with the Brugada syndrome is an exceptional but malignant and potentially lethal event. Efficient therapeutic solutions should be known and urgently applied because of the inability of usual antiarrhythmic means in preventing multiple recurrences of ventricular arrhythmias. Isoproterenol should be immediately infused while oral quinidine should be further administrated when isoproterenol is not effective. In case of failure of these therapeutic options, ablation of the triggering ventricular ectopies should be attempte

Large Circular Ring Catheter Ablation Versus Anatomically Guided Ablation of Atrial Fibrillation: Back to the Future for Successful Catheter Ablation of Atrial Fibrillation?

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An Approach to Catheter Ablation of Cavotricuspid Isthmus Dependent Atrial Flutter

Much of our understanding of the mechanisms of macro re-entrant atrial tachycardia comes from study of cavotricuspid isthmus (CTI) dependent atrial flutter. In the majority of cases, the diagnosis can be made from simple analysis of the surface ECG. Endocardial mapping during tachycardia allows confirmation of the macro re-entrant circuit within the right atrium while, at the same time, permitting curative catheter ablation targeting the critical isthmus of tissue located between the tricuspid annulus and the inferior vena cava. The procedure is short, safe and by demonstration of an electrophysiological endpoint - bidirectional conduction block across the CTI - is associated with an excellent outcome following ablation. It is now fair to say that catheter ablation should be considered as a first line therapy for patients with documented CTI-dependent atrial flutter

Attenuation of stretch-induced arrhythmias following chemical ablation of Purkinje fibres, in isolated rabbit hearts

Purkinje fibres (PFs) play an important role in some ventricular arrhythmias and acute ventricular stretch can evoke mechanically-induced arrhythmias. We tested whether Purkinje fibres, play a role in these arrhythmias. Pseudo-ECGs were recorded in isolated, Langendorff-perfused, rabbit hearts in which the left ventricular endocardial surface was also irrigated with Tyrode, via an indwelling catheter placed in the left ventricular lumen. The number and period of ectopic activations was measured during left ventricular lumen inflation via an indwelling fluid-filled balloon (500 μL added over 2 s and maintained for 15 s in total). Mechanically-induced arrhythmias occurred in 70% of balloon inflations: they were maximal in the first 5 s and ceased within 15 s. Brief, (10 s) irrigation of the left ventricular lumen with Lugol solution (IK/I2), via the indwelling catheter, reduced inflation-induced ectopics by 98% (p < 0.05). Ablation of endocardial PFs by Lugol was confirmed by Triphenyltetrazolium Chloride staining. Optical mapping revealed the left ventricular epicardial activation patterns of ectopics could have PF-mediated and focal sources. In silico modelling predicted ectopic sources originating in the endocardial region propagate to and through the Purkinje fibres network. Acute distention-induced ectopics are multi-focal, their attenuation by Lugol, their activation patterns and in silico modelling indicate a participation of Purkinje fibres in these arrhythmias

A Singularity-analysis Approach to characterize Epicardial Electric Potential

International audienceThe cardiac electrical activity conforms a complex sys- tem, for which nonlinear signal-processing is required to characterize it properly. In this context, an analysis in terms of singularity exponents is shown to provide compact and meaningful descriptors of the structure and dynam- ics. In particular, singularity components reconstruct the epicardial electric potential maps of human atria, inverse- mapped from surface potentials; such approach describe sinus-rhythm dynamics as well as atrial flutter and atrial fibrillation. We present several example cases in which the key descriptors in the form of fast-slow dynamics point at the arrhythmogenic areas in the atria

Electrical storm reversible by isoproterenol infusion in a striking case of early repolarization

A 40-year-old woman was referred to intensive care unit after recurrent ventricular fibrillation. She was free of cardiac medical history or medications. The resting ECG displayed an extended early repolarization in the inferior leads and all the precordial leads. Incessant ventricular fibrillations justified a treatment by intravenous amiodarone associated with general anaesthesia and mechanical ventilation without success on ventricular fibrillation. Because of a low heart rate intravenous isoproterenol infusion was initiated. Isoproterenol infusion was associated with heart rate acceleration and a decrease in J point elevation and the disappearance of ventricular fibrillation episodes. No cardiac disease was documented and the patient was implanted of a single chamber ICD. Six months later the patient was free of syncope and ventricular fibrillation on ICD memory. This case report demonstrates the usefulness and efficiency of the isoproterenol infusion to eliminate recurrent ventricular fibrillation in patients with early repolarization

A new ECG-based method to guide catheter ablation of ventricular tachycardia

International audienceINTRODUCTION Catheter ablation is used to treat ventricular tachycardia (VT). It uses radiofrequency energy to destroy a small part of heart tissue that is causing rapid and irregular heartbeats. Automated localization of VT exit sites can facilitate the long and often challenging ablation procedures but current methods are not accurate enough, cannot be used in some conditions, and often require detailed information about the patient's anatomy. The aim of this study was to optimize the accuracy of a previously proposed computer-based method for localization of arrhythmia exit sites. The effectiveness of the method was tested using simulated ECG data. We looked for optimal settings of the method allowing to apply it in clinical conditions.METHODS The proposed algorithm works on any set of 3 or more ECG leads. The QRS complex integral (QRSi) of an ectopic beat is reduced to principal components (PCs) treated as coordinates of the exit site in ECG space and then projected to real space by a linear transformation based on a small number of QRSis paced at known locations. The accuracy of the method was tested on 8 patient-tailored models of the human heart and torso. For each model ~500 simulations were run, each for a different stimulus location. A set of training points was randomly chosen and all other locations were then estimated from simulated surface ECGs. The absolute and relative (to a neighboring stimulation site) localization errors (in mm) were computed for a 252-lead ECG, and Frank VCG and using different numbers of training points and principal components.RESULTS The localization error depended on the size of the training set. By using patient’s mean transform matrix of stimulus position from ECG space to real space and Frank XYZ leads we found 15.5 ± 6.4 mm of mean absolute error. Starting from 9 pacing positions available and 3 PCs used we reached a similar level of mean error (15.22 ± 3.5 mm). With 20 stimulus points available and 7 PCs we got 10 ± 2 mm of error. Added noise had no significant influence on the results; even a 2 dB signal/noise ratio increased the error by only 1 mm.DISCUSSION This study suggests that the proposed method can predict exit sites with a precision in the order of a centimeter. By dynamically switching the settings of the algorithm it is possible to obtain better accuracy

In-Silico Data Based Machine Learning Technique Predicts Premature Ventricular Contraction Origin Coordinates

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