Mapping and ablation of atrial tachyarrhythmias : from signal to substrate

Biosense Webster/Johnson & Johnson Medical BV, St Jude Medical Nederland BV, Guidant Nederland BV, Boston Scientific Nederland, Merck, Sharp & Dome, Bard Electrophysiology, Philips Medical Systems, AstraZeneca BV, Schering Plough, Siemens, Servier, Astellas Pharmas, Toshiba Medical Systems Nederland BV, Medtronic BV and Vitatron.UBL - phd migration 201

Met de Hand op het Hartritme

Een hartritmestoornis is elke afwijkingen van het normale hartritme. Hartritmestoornissen komen steeds meer voor en hartritmestoornissen worden ook wel de cardiovasculaire epidemie van de 21e eeuw genoemd. De meest voorkomende hartritmestoornis is boezemfibrilleren, ook wel atriumfibrilleren genoemd. Tijdens deze openbare les neem ik u mee op reis door het verleden, heden en toekomst van de diagnostiek en therapie van hartritmestoornissen. Tevens laat ik u zien hoe elektrische signalen een sleutelrol spelen bij de toekomstige behandeling van hartritmestoornissen en ook hoe een trans disciplinaire samenwerking hier een bijdrage aan kan leveren

Direction- and rate-dependent fractionation during atrial fibrillation persistence: Unmasking cardiac anisotropy?

This human case is the first to illustrate morphological manifestations of direction- and rate-dependent anisotropic conduction in high-resolution unipolar atrial potentials. Premature impulses induced low-amplitude, fractionated extracellular potentials with exceptionally prolonged durations in a 76-year old longstanding persistent patient with atrial fibrillation (AF), demonstrating direction-dependency of anisotropic conduction. An increased pacing frequency induced presence of similar fractionated potentials, reflecting rate-dependent anisotropy and inhomogeneous, slow conduction. Pacing with different rates and from different sites could aid in identifying nonuniform anisotropic tissue and thus the substrate of AF

Catheter ablation of right ventricular outflow tract tachycardia using contact force guidance

Outflow tract tachycardias (OTT) originating from the right or left ventricular outflow tract are thought to be benign. However, symptoms can be disabling and deterioration of left ventricular function may occur with a high arrhythmia burden. Catheter ablation has a high acute success rate of up to 90 %, but recurrences are not uncommon [1, 2]. Novel catheter designs, and mapping and ablation technologies aim to improve procedural outcome, lower the complication rate, and increase the long-term success rate [3]. The TactiCath (R) catheter (TactiCath (R), Endosense, SA Meyrin/Geneva, Switzerland, distributed by Biotronik, Berlin, Germany) is a contact force (CF) sensing radiofrequency ablation catheter that provides real-time assessment of tip-to-tissue CF during ablation [4]. Until now, it has only been used in ablation of supraventricular tachycardias, mainly atrial fibrillation. In this report, we describe the case of a patient who underwent successful ablation of right ventricular OTT and ventricular premature beats (VPBs) using CF guidance. To the best of our knowledge, this is the first case ever described of OTT ablation using CF with the TactiCath (R) catheter

Left atrial diverticula: Innocent bystanders or wolves in sheep's clothing?

Introduction: The finding of left atria diverticula (LAD) on cardiac computed tomography images obtained from patients with atrial fibrillation (AF) referred for pulmonary vein isolation is not uncommon. Prior studies reporting on LAD do not always provide definitions of LAD resulting in confusion with other anatomical structures such as left atrial accessory appendages (LAAA) and atrial aneurysms. The aim of this review is to identify an accurate definition of LAD and to describe distinctive properties between LAD and other left atrial structures, such as LAAA and aneurysms. Also, the relation between LAD and development of atrial tachyarrhythmias is discussed. Methods: PubMed was searched for studies reporting on atrial aneurysms, left atrial diverticula, left atrial accessory appendages and atrial congenital aneurysms, resulting in 36 papers. Results: LAD can be distinguished from LAAA by taking into account embryologic origins of the left atrium and their locations, resulting in the following definitions: (a) LAAA are contractile, trabeculated structures with circumscriptive ostia and narrow necks, originating from the primitive atria, (b) LAD are contractile, sac like structures with either smooth or trabeculated inner surfaces, circumscriptive ostia, narrow necks, and variable morphologies, originating from the embryologic common pulmonary vein, that incorporates into the LA, and (c) atrial aneurysms are non-contractile structures with wide necks and sac like bodies. There are no differences in prevalences of LAD between patients with sinus rhythm and AF. Conclusion: The pathophysiology of LAD is not yet fully understood. It is unlikely, that LAD are related to the development of atrial tachycardia's and AF by either being a source of ectopic activity or being part of an arrhythmogenic substrate. No differences in LAD prevalences between patients with sinus rhythm and AF have been found. Thus, it is unlikely that LAD could potentially be wolves in sheep's clothing

Estimation of high-density activation maps during atrial fibrillation

The study of activation maps using multi-electrode arrays (MEA) can help to understand atrial fibrillation (AF) mechanisms. Activation mapping based on recorded unipolar electrograms (u-EGM) rely on the local activation time (LAT) detector, which has a limited robustness, accuracy, and generally requires manual post-edition. In general, LAT detection ignores spatiotemporal information about activation and conduction conveyed by the relation between signals of the MEA sensor. This work proposes an approach to construct activation maps by simultaneous analysis of u-EGMs from small clusters of MEA electrodes. The algorithm iteratively fits an activation pattern model to the acquired data. Accuracy was evaluated by comparing with audited maps created by expert electrophysiologists from a patient undergoing open-chest surgery during AF. The estimation error was -0.29 ± 6.01 ms (236 maps, 28369 LATs) with high correlation (¿ = 0.93). Therefore, activation maps can be decomposed into local activation patterns derived from fitting an activation model, resulting in smooth and comprehensive high-density activation maps

Exploring Refractoriness as an Adjunctive Electrical Biomarker for Staging of Atrial Fibrillation

Patients diagnosed with the same subtype of atrial fibrillation according to our current classification system may differ in symptom severity, severity of the arrhythmogenic substrate, and response to antiarrhythmic therapy. Hence, there is a need for an electrical biomarker as an indicator of the arrhythmogenic substrate underlying atrial fibrillation enabling patient-tailored therapy. The aim of this review is to investigate whether atrial refractoriness, a well-known electrophysiological parameter that is affected by electrical remodeling, can be used as an electrical biomarker of the arrhythmogenic substrate underlying atrial fibrillation. We discuss methodologies of atrial effective refractory period assessment, identify which changes in refractoriness-related parameters reflect different degrees of electrical remodeling, and explore whether these parameters can be used to predict clinical outcomes