Local activation time sampling density for atrial tachycardia contact mapping: how much is enough?

Figures

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  Figure 1. Optimal LAT sampling densities. Calculated optimal LAT sampling densities are shown for simulated activation patterns (A) and in vivo LA activation patterns (B). FO, focal origin; MA, macro re-entry; MI, micro (localised) re-entry.

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  Figure 2. The process used for determination of optimal LAT sampling density. (A) The process is shown for a focal tachycardia in a 4×4 cm monolayer with fiber orientation of 18° to the x-axis. (B) Activation times are re-sampled at increasing sampling density and regional activation is re-interpolated to give the resulting ‘down-sampled’ activation maps. Sampling densities (points/cm2) are given above each example map. (C) Mean normalized LAT map error at each sampling density is calculated by comparing activation times at each node with the original activation times in A. (D) Taking the first-derivative of the curve in ‘C’ indicates the sampling density at which minimal further improvement in map accuracy is generated.

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  Figure 3. Clinical isochronal local activation time maps. Local activation time (LAT) maps for example clinical tachycardias are shown. Tachycardia mechanisms (confirmed by response to entrainment manoeuvres and to ablation) are given as headings in each column. (A) focal activation in low posterior LA; (B) perimitral macro-re-entry; (C) localized anterior re-entry. Anterior-posterior and posterior-anterior projections are shown (top and bottom row respectively). Left-most maps of each pair are the original isochronal maps produced at the time of the clinical procedure with purple dots representing sampled LAT point locations. Right-most maps of each pair are single examples of re-interpolated maps generated at the calculated optimal densities with black dots representing the re-sampled point locations. MV indicates the mitral valve annulus; * indicates the site of focal activation.

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  Figure 4. Porcine right atrial LAT maps. (A) Pre-ablation LAT shows uniform activation across the chamber from coronary sinus towards the right atrial appendage. (B) Post-ablation LAT shows a new activation detour (asterisk) via the mid-chamber gap in the ablation line. Ablation points are shown with red tags and catheter positions during ablation with pink dots using the Visitag Carto3 module. (C) Comparison between optimal LAT sampling density for pre- and post-ablation LAT maps.

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  Figure 5. Initiation of activation patterns in the atrial monolayer. (A) Linear activation; (B) focal activation; (C) re-entrant activation; and (D) spiral wave activation. Stimulated regions are shown in white in the left-most column of each row.

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  Figure 6. Simulated isochronal local activation time maps. (A) Linear activation; (B) focal activation; (C) re-entrant activation; and (D) spiral wave activation. Reference LAT maps are shown in the left most column. In A and B, local activation time is taken as the first activation of each node. In C and D, a window of interest (WOI) incorporating 100% of the tachycardia cycle length (TCL) was specified. Grey colour represents tissue that is never activated during the WOI—either non-conducting (C) or functionally refractory (D).