Application of Ripple Mapping to Visualize Slow Conduction Channels Within the Infarct-Related Left Ventricular Scar

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P ost-infarct reentrant ventricular tachycardia (VT) is dependent on channels of surviving myocardium within the infarct scar.1 Substrate-based ablation that eliminates all abnormal electrograms, including fractionated and late potentials within scar, can reduce long-term VT recurrence. However, detailed mapping studies of local electrograms can identify paths of activation within the scar, forming channels that are considered a more specific target for substrate ablation. 3,4 Ripple mapping (RM) is a method of 3-dimensional activation visualization that displays each electrogram component as a dynamic bar that protrudes from its 3-dimensional location on the surface geometry. 5 The height of each bar correlates with the voltage amplitude of the electrogram at that time point. When multiple points are collected, activation is visually apparent from the direction of propagation of bar movement on the map. This is achieved without the need for manual annotation or setting a window of interest. Ripple activation maps can be superimposed on a conventional bipolar voltage map, thereby displaying the surface geometry with both voltage and activation simultaneously.6,7 RM is incorporated into CARTO3v4 (Biosense Webster) and has been © 2016 American Heart Association, Inc. Original ArticleBackground-Post-infarct ventricular tachycardia is associated with channels of surviving myocardium within scar characterized by fractionated and low-amplitude signals usually occurring late during sinus rhythm. Conventional automated algorithms for 3-dimensional electro-anatomic mapping cannot differentiate the delayed local signal of conduction within the scar from the initial far-field signal generated by surrounding healthy tissue. Ripple mapping displays every deflection of an electrogram, thereby providing fully informative activation sequences. We prospectively used CARTO-based ripple maps to identify conducting channels as a target for ablation. Methods and Results-High-density bipolar left ventricular endocardial electrograms were collected using CARTO3v4 in sinus rhythm or ventricular pacing and reviewed for ripple mapping conducting channel identification. Fifteen consecutive patients (median age 68 years, left ventricular ejection fraction 30%) were studied (6 month preprocedural implantable cardioverter defibrillator therapies: median 19 ATP events [Q1-Q3=4-93] and 1 shock [Q1-Q3=0-3]). Scar (<1.5 mV) occupied a median 29% of the total surface area (median 540 points collected within scar). A median of 2 ripple mapping conducting channels were seen within each scar (length 60 mm; initial component 0.44 mV; delayed component 0.20 mV; conduction 55 cm/s). Ablation was performed along all identified ripple mapping conducting channels (median 18 lesions) and any presumed interconnected late-activating sites (median 6 lesions; Q1-Q3=2-12). The diastolic isthmus in ventricular tachycardia was mapped in 3 patients and colocated within the ripple mapping conducting channels identified. Ventricular tachycardia was noninducible in 8...

Section: Discussionmentioning

confidence: 52%

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confidence: 91%

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

Luther

Linton

Jamil‐Copley

et al. 2016

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“…19 Jamil-Copley et al more recently showed the potential utility of ripple mapping which demonstrates both voltage and propagation channels into scar in a single dynamic display. 20 This technology has the advantage of displaying complex or continuous fractionated local electrograms as time-dependent propagation, rather than choosing a single annotation for timing.…”

Section: Discussionmentioning

confidence: 99%

Relationship Between Sinus Rhythm Late Activation Zones and Critical Sites for Scar-Related Ventricular Tachycardia

Irie

Bradfield

et al. 2015

158

110

Background It is not known if the most delayed late potentials are functionally most specific for scar-related ventricular tachycardia (VT) circuits. Methods and Results Isochronal late activation maps (ILAM) were constructed to display ventricular activation during sinus rhythm over eight isochrones. Analysis was performed at successful VT termination sites and prospectively tested. 33 patients with 47 scar-related VTs where a critical site was demonstrated by termination of VT during ablation were retrospectively analyzed. In those that underwent mapping of multiple surfaces, 90% of critical sites were on the surface that contained the latest late potential. However, only 11% of critical sites were localized to the latest isochrone (87.5–100%) of ventricular activation. The median percentage of latest activation at critical sites was 78% at a distance from the latest isochrone of 18 mm. Sites critical to reentry were harbored in regions with slow conduction velocity, where 3 isochrones were present within a 1 cm radius. 10 consecutive patients underwent ablation prospectively guided by ILAM, targeting concentric isochrones outside of the latest isochrone. Elimination of the targeted VT was achieved in 90%. Termination of VT was achieved in 6 patients at a mean ventricular activation percentage of 78%, with only 1 requiring ablation in the latest isochrone. Conclusions Late potentials identified in the latest isochrone of activation during sinus rhythm are infrequently correlated with successful ablation sites for VT. The targeting of slow conduction regions propagating into the latest zone of activation may be a novel and promising strategy for substrate modification.

“…Multiple points are displayed, with the timing of each point being relative to a fiducial reference signal. 7,8 This is then presented as a movie to allow visualization of the activation wavefront direction. By superimposing the bars on a display of bipolar voltage amplitude, RM is unique in presenting both voltage as well as activation information on the same shell ( Figure 1 and Movie I in the Data Supplement).…”

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confidence: 99%

A Prospective Study of Ripple Mapping in Atrial Tachycardias

Luther

Linton

Koa‐Wing

et al. 2016

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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.