Spatio-Temporal Activation Wavefront Reconstruction From Sparsely Sampled Electrograms

Abstract

Objective: Panoramic basket catheters offer a rapid alternative to conventional local activation time (LAT) mapping for visualizing conduction patterns in arrhythmia patients. However, their limited spatial resolution often makes producing highly interpretable visualizations of the underlying phenomena challenging. We propose a novel interpolation method that addresses uncertainties arising from limited spatial resolution and variable tissue contact associated with basket catheters. By leveraging high sampling rates in the time domain to impose spatio-temporal constraints on the reconstruction, we enable enhanced spatial resolution in visualizing wave propagation. Methods: We constructed overlapping triangles from adjacent electrodes. The local apparent conduction velocity (CV) was estimated from cross-correlations of signals, and the triangles were classified into linear conducting, singularity, and non-conducting types based on CV and goodness of fit. Within each triangle, a linear constraint was imposed on the reconstruction, depending on the triangle type, by projecting signals along the CV. A smoothness constraint was added to ensure consistency at clique boundaries. The hyperparameters were calibrated in an unsupervised manner. Results: The proposed method reduced the activation time estimation error by up to 15% compared to traditional interpolation methods in simulations and showed qualitative consistency with LAT maps in clinical cases. Conclusion: The method enhances spatial resolution in panoramic mapping, mitigating aliasing and signal artifacts, especially in regions with complex wavefronts or large inter-electrode distances. Significance: The proposed method enables fast and accurate visualizations of panoramic conduction patterns from a single atrial cycle, potentially reducing procedure times compared to sequential mapping.