Epicardial and Endocardial Ablation Based on Channel Mapping in Patients With Ventricular Tachycardia and Chronic Chagasic Cardiomyopathy: Importance of Late Potential Mapping During Sinus Rhythm to Recognize the Critical Substrate

Figures

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  Figure 1. Endo‐epicardial ventricular bipolar voltage mapping during sinus rhythm (patient 3). A low‐voltage area exhibiting late potentials was identified in posterolateral basal segments of the left ventricle. A sample of 2 electrograms recorded during point‐by‐point mapping is indicated by the abnormal signals in the border zone (A) and dense scar (B). In this color‐coded voltage map, red indicates a dense scar (<0.5 mV); purple, normal tissue (>1.5 mV); and the remaining colors represent the border zone (0.5–1.5 mV).

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  Figure 2. Epicardial arrhythmogenic substrate defined by voltage and activation mapping during sinus rhythm (patient 8). Activation mapping was initially set up (A) using the measure of the QRSpeak–QRSend interval (51 ms) that was inserted as the cutoff for the color scale (B). Two nonconfluent areas containing late potentials, displayed in purple (C), were identified within the epicardial dense scar (D). Pace mapping performed in these 2 regions, termed late activation zones (LAZ), was related to inducible ventricular tachycardias (VT); pacemap 1 (PM1) matched to VT1 (E), and pacemap 2 (PM2) matched to VT2 (F). The sectors of the LAZ (white dashed line) are represented as the core zone (CZ), within the dense scar (red dashed line), and the entrance zone (EZ—yellow box), near of the border of the scar (G).

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  Figure 3. Abnormal bipolar electrograms typically recorded in the chagasic substrate (patient 13). A, Low‐amplitude electrogram (0.56 mV) with duration of 50 ms and 2 positive deflections recorded in the border zone of left ventricular endocardial scar; (B) low‐voltage signal (0.20 mV) displaying an isolated diastolic potential (IDP) recorded 42 ms after the end of QRS; (C) another sample of IDP with an amplitude of 0.14 mV and an interval between end QRS and split signal of 132 ms. Both delayed electrograms (B and C) were recorded inside of the late activation zone (LAZ) and dense scar area of the endocardium and epicardium, respectively; (D) late fragmented potential (LFP) showing multicomponent deflections (5 positive deflections) after the end of QRS (latency of 50 ms) was recorded near the border zone of the endocardial scar (0.40 mV) and within of the entrance of the LAZ; (E and F) both LFPs exhibiting a delayed (48 ms) and very delayed (120 ms) signal after the QRS was recorded inside of the core of the LAZ and dense scar of the endocardial (0.25 mV) and epicardial (0.18 mV) mapping, respectively.

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  Figure 4. Complete elimination of the late potentials by endo‐epicardial catheter ablation (patient 16). Left ventricle endocardial (A and C) and epicardial (B and D) mapping are displayed in posterosuperior and posterolateral projections, respectively. Bipolar voltage mapping identified a large confluent transmural epicardial (B) and endocardial (A) scar that includes areas exhibiting late potentials, as shown in the late activation maps (C and D). Red dots represent the sites where radiofrequency (RF) energy was delivered to eliminate all late potentials. In the right image (E), progressive slowing of an isolated diastolic potential (arrow) until disappearance is shown during delivery of RF ablation.

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  Figure 5. Comparison of endocardial and epicardial areas of the chagasic substrate. Scar and LAZ areas measured in each patient (A). The mean (B) and median (C) were showed to compare scar area (*), LAZ area and percentage of LAZ related with the scar (LAZ/scar) between the endocardium (endo) and epicardium (epi). LAZ indicates late activation zone; and Pt, patient. *Scar areas were a non‐normally distributed data.

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  Figure 6. Kaplan‐Meier curve depicting freedom from recurrent ventricular tachycardia (VT) in chagasic patients submitted to substrate ablation with (red line) or without (blue line) elimination of late potentials (LP).