A Prospective Study of Ripple Mapping in Atrial Tachycardias

Abstract

Background-Post ablation atrial tachycardias are characterized by low-voltage signals that challenge current mapping methods. Ripple mapping (RM) displays every electrogram deflection as a bar moving from the cardiac surface, resulting in the impression of propagating wavefronts when a series of bars move consecutively. RM displays fractionated signals in their entirety thereby helping to identify propagating activation in low-voltage areas from nonconducting tissue. We prospectively used RM to study tachycardia activation in the previously ablated left atrium. Methods and Results-Patients referred for atrial tachycardia ablation underwent dense electroanatomic point collection using CARTO3v4. RM was played over a bipolar voltage map and used to determine the voltage "activation threshold" that differentiated functional low voltage from nonconducting areas for each map. Ablation was guided by RM, but operators could perform entrainment or review the isochronal activation map for diagnostic uncertainty. Twenty patients were studied. Median RM determined activation threshold was 0.3 mV (0.19-0.33), with nonconducting tissue covering 33±9% of the mapped surface. All tachycardias crossed an isthmus (median, 0.52 mV, 13 mm) bordered by nonconducting tissue (70%) or had a breakout source (median, 0.35 mV) moving away from nonconducting tissue (30%). In reentrant circuits (14/20) the path length was measured (87-202 mm), with 9 of 14 also supporting a bystander circuit (path lengths, 147-234 mm). In breakout tachycardias, splitting of wavefronts resulted in 2 to 4 incomplete circuits. RMguided ablation interrupted the tachycardia in 19 of 20 cases with the first ablation set. Conclusions-RM helps to define activation through low-voltage regions and aids ablation of atrial tachycardias.(Circ Arrhythm Electrophysiol. 2016;9:e003582.

Identification of critical isthmus using coherent mapping in patients with scar‐related atrial tachycardia

“…Map consistency display was used to search for, and filter points whose LAT values are not consistent with the LAT values of neighboring points to highlight these outliers. The interpolation threshold of the color fill‐in of the reconstruction was set at 5% during map acquisition to permit a relatively uniform density of mapping points 15 . Bipolar electrograms were filtered between 16 and 500 Hz, unipolar electrograms between 2 and 240 Hz and recorded digitally 7 .…”

“…SNO zones were the result of the coherent mapping algorithm, exhibit absence of conduction velocity vectors on coherent map, and appear as brown on the 3D maps (Figure 1A). 15 For optimal performance, the following were likewise adjusted. Scar settings were defined with a voltage cutoff of less than 0.05 and less than 0.5 mV used to define scar and low voltage zones, respectively 16 …”

A Prospective Study of Ripple Mapping the Post-Infarct Ventricular Scar to Guide Substrate Ablation for Ventricular Tachycardia

“…6,7 RM is incorporated into CARTO3v4 (Biosense Webster) and has been Ripple Mapping in Post-Infarct VT applied prospectively to guide atrial tachycardia ablation in the scarred atrium. 8 We have previously described how RM is able to visualize conducting channels of electrogram activation within scar using an offline system in a retrospective series of ventricular substrate maps. 9 This showed that pacing sites with good pace maps and where entrainment mapping confirmed participation in VT colocated with the identified ripple mapping conducting channels (RMCCs).…”

Arrhythmia Mechanisms Revealed by Ripple Mapping

“…9,10 We described active tissue thresholding, which helps to define the critical isthmus sites supporting re-entry as a target for ablation: by superimposing ripple activation on a bipolar voltage display, areas without any visible ripple activation can be inferred to be scar and colour-coded red on a voltage map. 11 An example of this is illustrated in Figure 3 for mapping an organised AT in an atrium with previous extensive ablation for AF, where the local activation colour sequence is uninterpretable.…”

“…However, we have found that simultaneous display of the bipolar EGM voltage is helpful in interpretation of ripple map activation, particularly when understanding arrhythmia mechanisms and their relation to scarred substrates. 11,12 RM has been incorporated into a commercially available electroanatomic mapping system, CARTO ® 3 (Biosense Webster), so it can be used to guide ablation at the time of mapping. In the following sections we will review our experience of RM in elucidating the mechanisms of tachycardia within atrial and ventricular scar.…”