A method for assessing the sampling bandwidth for activation time and voltage maps in cardiac navigators

Current Sequential Cardiac Navigation Systems (SCNS) are widely used for creating either voltage or delay maps of the heart, allowing the physician to determine adequate therapy strategies and ablation targets. Given that the number or recorded electrograms (EGM) is a major determinant of the clinical procedure duration, our aim was to propose a method suitable for analyzing the spatial sampling rate that is required for obtaining quality spatial maps. A simple approach consisted on projecting a given feature measured from the available set of EGM (activation time, unipolar and bipolar EGM amplitudes) into a 2D image, according to the azimuth and elevation coordinates of its spatial location, using the chamber gravity center as coordinate origin. This image was reinterpolated into a uniform grid by using a k-Nearest Neighbor method, and the bandwidth was determined from the 2D Fourier Transform. A conservative bandwidth of WdB was used. We analyzed cases of right atria focal tachycardia (2) and flutter (2), using Carto¿ XP SCNS. Average bandwidths for activation time and (unipolar and bipolar) voltage maps were (2.19,1.25,1.48 rad^-1)for atrial focal tachycardia, and (2.34, 1.79, 2.19 rad^-1) for atrial flutter. Trends were observed for atrial flutter requiring higher bandwidths in all the features. Activation time required more bandwidth, whereas unipolar amplitude required the least. In conclusion, the method allows to analyze the spatial sampling requirements of current SCNS in terms of the arrhythmic substrate.