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

Abstract

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...

Utility of ripple mapping for identification of slow conduction channels during ventricular tachycardia ablation in the setting of arrhythmogenic right ventricular cardiomyopathy

“…There has been no recurrence of VT during a follow-up period of > 53 months RM preserves all components of the electrogram, optimally displays delayed low-amplitude local activation within scar and has been used to identify slow conduction channels within postinfarct scar during catheter ablation. 4,5 RMCC streamline the process to understand the spatial and sequential activation of delayed potentials through scar and provide a representation of what experienced electrophysiologists have always performed in their mind when using conventional mapping. Like a postinfarct scar, the fibrofatty myocardial replacement in ARVC leads to extensive networks of delayed and fractioned potentials in both the endocardial and epicardial RV.…”

“…3 The RM methodology has been demonstrated to be effective for the identification of conduction channels and for functional substrate ablation within the postinfarction scar. 4,5 In this study, we sought to (a) study the utility of RM for visualization of continuous corridors of sequential late activation within scar, termed conduction channels (RMCC), (b) define the association between complete RMCC ablation and ventricular tachycardia (VT) recurrence, and (c) examine the association of RMCC with image characteristics on late-gadolinium enhanced (LGE) magnetic resonance imaging (MRI) in a cohort of patients with ARVC.…”

2019 APHRS expert consensus statement on three‐dimensional mapping systems for tachycardia developed in collaboration with HRS, EHRA, and LAHRS

“…Automated identification of arrhythmogenic substrate has included mapping of signal amplitude and manual inspection of maps to identify sites of latest ventricular activation, or of myocardial bundles surrounded by denser scar based on signal amplitude or response to pacing . A newer technique, known as ripple mapping, retains the complexity of recorded signals and graphically portrays local signal amplitude over time in animated images . Rather than simplifying signals into a single activation time, or peak amplitude, this method permits visual analysis of the entire signal and can display conducting channels displayed within scars …”

Catheter Ablation of Scar-mediated Ventricular Tachycardia: Are Substrate-based Approaches Replacing Mapping?

“…Ripple mapping with the CARTO ® 3 system (Biosense Webster, Diamond Bar, CA, USA) is a more sophisticated 3D display of the propagating wavefront, allowing slowly conducting channels within ischemic scar to be better visualized, making the process of identifying critical isthmuses within scar with activation mapping more feasible. 47 Electrocardiographic imaging using a 252-electrode vest is being evaluated as a noninvasive 3D mapping option that can facilitate the preprocedural mapping of VT. 48 While delayed-enhanced cardiac MRI has been shown to aid in identifying scarring not apparent with electroanatomic mapping, 49 inadequate spatial resolution for identifying critical isthmuses has remained a major limitation of current technology. Real-time MRI guidance may better facilitate VT ablation and continues to be evaluated.…”