40Dot mapping: a novel technique for dual electrophysiological dataset representation facilitates recognition of complex intra-atrial re-entrant tachycardia substrate in repaired adult congenital heart disease

Abstract

Introduction: Adult congenital heart disease (ACHD) patients have a high lifetime prevalence of reentrant atrial arrhythmia, secondary to both the anatomic lesion and surgical repair. Catheter ablation is an effective treatment for atrial tachycardia (AT), however current electroanatomical mapping (EAM) systems permit the display of only a single data modality per shell at a given time. Localised voltages can reveal prior structural information critically related to arrhythmia mechanisms. A bipolar voltage threshold of <0.05mV has traditionally been accepted for the annotation of scar (based on the noise threshold of the Carto system), with voltage <0.5mV taken to represent abnormal atrial tissue. We sought to assess the feasibility of dual representation of activation time (LAT) and voltage on the atrial shell of patients with repaired congenital heart disease. Methods: Surface shading was used to represent LAT and finely spaced dots (‘Dot Mapping’) were utilized to represent voltage. Low voltages are represented by high dot density and the cloud overlaid on the activation map (see Figure 1). Dot positions are randomized within triangular (surface meshes) or tetrahedral (volumetric meshes) simplices making the approach directly transferrable to contemporary EAM systems. In order to assess the feasibility of co-representation, users (n=10) completed a 5-point Likert scale questionnaire covering three domains (diagnostic accuracy, display fidelity and dataset co-registration) for both Dot Maps and traditional color maps. Subsequently, the technique was applied to seventeen patients with repaired ACHD who had undergone catheter ablation procedure for AT using CARTO3. Voltage and activation time datasets were exported for offline co-display using Matlab. Results: With 5 items in each domain, the maximum score per domain is 25. Dot Mapping out-performed color maps in the “Dataset co-registration” domain (median score 24.5 vs 10, p<0.05, Wilcoxon two-sample signed rank), “Diagnostic accuracy” (17 vs 21) and “Display fidelity” (18 vs 20) scored similarly, indicating that the Dot Mapping software faithfully represents the input datasets. Conclusion: Dot mapping facilitates co-display of complimentary data sets. Interpretation of activation time maps in the context of structural arrhythmia substrate may improve diagnosis of mechanisms of complex atrial arrhythmias in repaired ACHD. ![Graphic][1] Figure 1 Demonstrates a representative example of a repaired congenital heart disease dataset with voltage information overlaid on a localized activation time map. [1]: /embed/inline-graphic-1.gif