Coherent mapping: A step toward physiological mapping of complex arrhythmias?

Abstract

Complex atrial tachycardias (AT) are commonly encountered in clinical practice either as a result of prior cardiac surgery, 1 as a secondary consequence of substrate and linear based atrial fibrillation ablation, 2 or de novo in the presence of advanced electroanatomical remodeling associated with structural heart disease. 3 The mechanism of these ATs is typically macro-reentry but small circuit re-entry and focal tachycardias may also occur in relation to regional scarring. In the setting of advanced electroanatomic substrate these circuits can be extremely challenging to map and ablate. Extensive regions of complex signals not necessarily involved in the tachycardia and multiple lines of conduction slowing and block can create the visual appearance of critical zones and circuits which are actually entirely passive. 4 These patients may also have multiple frequently changing and unstable circuits. Activation, voltage, and entrainment mapping are the key approaches used in the electrophysiology lab to efficiently identify the circuit and more importantly, the critical isthmus. These approaches should be viewed as complementary: each has potential pitfalls and all require careful interpretation in the context of all the information. Three dimensional electroanatomic mapping with multi-electrode catheters is now "standard" and the collection of thousands of points per "map" routine. However, accurate automated LA annotation of complex bipolar multicomponent electrogram's continues to present a challenge that to date lacks a reliable solution. Accurate map creation therefore demands meticulous manual assessment and re-annotation of complex electrograms in areas of slowed conduction that are often found at or adjacent to the critical isthmus. In the context of limitations which may mislead even the most experienced operator, 4 entrainment mapping has continued to play a fundamental role in localizing critical regions to focus the 3D map.To overcome these limitations, Anter et al 5 recently described the utility of the coherent mapping module and its ability to describe complex patterns of propagation to better define mechanism and guide ablation of complex atrial arrhythmias. This novel mapping algorithm (coherent mapping, Biosense Webster) aims to provide a physiological framework for 3D mapping by considering global patterns of activation, identifying areas of slow and discontinuous conduction so that the end user can understand complex re-entrant mechanisms and formulate an ablation strategy. The validation study showed that the algorithm was superior to standard local activation time (LAT) for both identification of the mechanism and predicting the site of termination of AT's In this issue of the Journal, Vicera et al 6 report their experience comparing coherent mapping with standard activation maps in identifying the critical isthmus in patients with scar-related AT. In 20 consecutive patients, 26 complex AT's (defined as AT occurring after previous cardiac surgery or ablation) were systematically mapped using a...

Focally Appearing Activation Map of a Reentrant Tachycardia Using a New Coherent Mapping Tool

“…This algorithm uses the local activation time values of all the points in a map and performs an iterative calculation to discern a global bestfit solution in these arrhythmias, analogous to calculating a regression line to show how scattered points indicate a global trend. 3 The mechanism of the AVRT is reentry and mapping only one limb of the tachycardia circuit would yield a centrifugal pattern of activation and may help to precisely locate the target for ablation. There is also a potential for demonstrating the pathway with a slant by mapping other (ventricular) sites as well.…”

A Study of Arrhythmia Risk Level Discrimination Based on K-Means Algorithm and Analytic Hierarchy Method

“…Ramanathan P, M J K, and Geoffrey L, in "Coherent mapping: a step toward physiological mapping of complex arrhythmias?" [1], explored the physiological mapping approach to understand the mechanisms of complex arrhythmias and assess the degree of risk, providing a new avenue for the field. Neira V, Santangeli P, Futyma P et al in "Ablation strategies for intramural ventricular arrhythmias" [2] studied ablation strategies for ventricular arrhythmias in the inner wall of the heart, which provides ideas for the treatment of arrhythmias with high degree of risk.…”