Critical appraisal of technologies to assess electrical activity during atrial fibrillation: a position paper from the European Heart Rhythm Association and European Society of Cardiology Working Group on eCardiology in collaboration with the Heart Rhythm Society, Asia Pacific Heart Rhythm Society, Latin American Heart Rhythm Society and Computing in Cardiology

We aim to provide a critical appraisal of basic concepts underlying signal recording and processing technologies applied for (i) atrial fibrillation (AF) mapping to unravel AF mechanisms and/or identifying target sites for AF therapy and (ii) AF detection, to optimize usage of technologies, stimulate research aimed at closing knowledge gaps, and developing ideal AF recording and processing technologies. Recording and processing techniques for assessment of electrical activity during AF essential for diagnosis and guiding ablative therapy including body surface electrocardiograms (ECG) and endo- or epicardial electrograms (EGM) are evaluated. Discussion of (i) differences in uni-, bi-, and multi-polar (omnipolar/Laplacian) recording modes, (ii) impact of recording technologies on EGM morphology, (iii) global or local mapping using various types of EGM involving signal processing techniques including isochronal-, voltage- fractionation-, dipole density-, and rotor mapping, enabling derivation of parameters like atrial rate, entropy, conduction velocity/direction, (iv) value of epicardial and optical mapping, (v) AF detection by cardiac implantable electronic devices containing various detection algorithms applicable to stored EGMs, (vi) contribution of machine learning (ML) to further improvement of signals processing technologies. Recording and processing of EGM (or ECG) are the cornerstones of (body surface) mapping of AF. Currently available AF recording and processing technologies are mainly restricted to specific applications or have technological limitations. Improvements in AF mapping by obtaining highest fidelity source signals (e.g. catheter–electrode combinations) for signal processing (e.g. filtering, digitization, and noise elimination) is of utmost importance. Novel acquisition instruments (multi-polar catheters combined with improved physical modelling and ML techniques) will enable enhanced and automated interpretation of EGM recordings in the near future

Challenges associated with interpreting mechanisms of AF

Determining optimal treatment strategies for complex arrhythmogenesis in AF is confounded by the lack of consensus regarding the mechanisms causing AF. Studies report different mechanisms for AF, ranging from hierarchical drivers to anarchical multiple activation wavelets. Differences in the assessment of AF mechanisms are likely due to AF being recorded across diverse models using different investigational tools, spatial scales and clinical populations. The authors review different AF mechanisms, including anatomical and functional re-entry, hierarchical drivers and anarchical multiple wavelets. They then describe different cardiac mapping techniques and analysis tools, including activation mapping, phase mapping and fibrosis identification. They explain and review different data challenges, including differences between recording devices in spatial and temporal resolutions, spatial coverage and recording surface, and report clinical outcomes using different data modalities. They suggest future research directions for investigating the mechanisms underlying human AF

Innovations and mechanisms in pacing therapy for heart failure

Despite pharmacological advances, heart failure remains a major cause of mortality and morbidity. Pacing therapy for heart failure was achieved in the 1990s with the advent of biventricular pacing (BVP). BVP shortens ventricular activation time and has thus been referred to as ‘cardiac resynchronization therapy’ (CRT). However BVP has other effects including shortening of atrioventricular delay: the contributions of its effects to its overall benefit have yet to be elucidated. Ventricular activation is not normalised by BVP, indicating scope for more effective resynchronization. This thesis explores mechanisms and innovations in pacing therapy for heart failure through measurement of haemodynamic and electrical parameters with high precision and resolution during BVP, right ventricular pacing (RVP) and His bundle pacing (HBP), where the His-Purkinje conduction system is directly stimulated. HBP offers both an innovation in pacing and a model to study conventional pacing. HBP can deliver physiological CRT by overcoming left bundle branch block (LBBB) to normalise QRS appearances but its performance relative to BVP is not known. When performed proximally, or using lower energy, HBP can preserve intrinsic LBBB. In Chapter 3, the electro-mechanical effects of conventional BVP are compared with LBBB correction by HBP. Chapter 4 uses non-invasive electrical mapping to identify mechanisms and predictors of LBBB correction by HBP, comparing it with narrow QRS. Capture of the His bundle can be alone (selective HBP) or alongside myocardial capture (non-selective): the effect of this on HBP is studied in Chapter 5. In Chapter 6, the haemodynamic effects of proximal/low-energy HBP, where LBBB is preserved but atrioventricular timing can be optimised, is compared to BVP and RVP to measure the contribution of atrioventricular delay shortening to the overall benefit of BVP. By evaluating innovative therapies and improving our understanding of existing therapies, hopefully this thesis will advance pacing therapy for heart failure.Open Acces

Cardiac Propagation Pattern Mapping With Vector Field for Helping Tachyarrhythmias Diagnosis With Clinical Tridimensional Electro-Anatomical Mapping Tools

Ventricular (VT) and atrial (AT) tachycardias are some of the most common clinical cardiac arrhythmias. For ablation of tachycardia substrates, two clinical diagnosis methods are used: invasive electroanatomical mapping for an accurate diagnosis using electrograms (EGMs) acquired with intracardiac catheters, and localized on the surface mesh of the studied cavities; and noninvasive electrocardiographic imaging (ECGi) for a global view of the arrhythmia, with EGMs mathematically reconstructed from body surface electrocardiograms using 3-D cardio-thoracic surface meshes obtained from CT-scans. In clinics, VT and AT are diagnosed by studying activation time maps that depict the propagation of the activation wavefront on the cardiac mesh. Nevertheless, slow conduction areas-a well-known proarrhythmic feature for tachycardias-and tachycardia specific propagation patterns are not easily identifiable with these maps. Therefore, local characterization of the activation wavefront propagation can be helpful for improving VT and AT diagnoses. The purpose of this study is to develop a method to locally characterize the activation wavefront propagation for clinical data. For this, a conduction velocity vector field is estimated and analyzed using divergence and curl mathematical operators. The workflow was first validated on a simulated database from computer models, and then applied to a clinical database obtained from ECGi to improve AT diagnosis. The results show the relevancy and the efficacy of the proposed method to guide ablation of tachyarrhythmias

Proteomics

Biomedical research has entered a new era of characterizing a disease or a protein on a global scale. In the post-genomic era, Proteomics now plays an increasingly important role in dissecting molecular functions of proteins and discovering biomarkers in human diseases. Mass spectrometry, two-dimensional gel electrophoresis, and high-density antibody and protein arrays are some of the most commonly used methods in the Proteomics field. This book covers four important and diverse areas of current proteomic research: Proteomic Discovery of Disease Biomarkers, Proteomic Analysis of Protein Functions, Proteomic Approaches to Dissecting Disease Processes, and Organelles and Secretome Proteomics. We believe that clinicians, students and laboratory researchers who are interested in Proteomics and its applications in the biomedical field will find this book useful and enlightening. The use of proteomic methods in studying proteins in various human diseases has become an essential part of biomedical research