Reconsidering the utility of manifest entrainment pacing in macroreentrant ventricular tachycardia: A case report

Figures

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  Figure 1. After insertion of a small electrode catheter into the posterior lateral vein and placement of the MAP catheter on the endocardial surface opposite to the vein (A), intracardiac electrograms were evaluated during both sinus rhythm and the ventricular tachycardia (VT) (B). After 2 sinus beats, the VT was spontaneously initiated. The sharp potential preceded the surface QRS complex by 66 ms during the VT, and the electrodes of the EPI 1-2 became the earliest activation sites of the entire electrodes. Entrainment pacing from the distal small electrodes (EPI 1-2) revealed entrainment with concealed fusion (C). I, II, III, aVR, aVL, aVF, V1, V2, V3, V4, and V5 represent the surface electrocardiogram leads; CS 1-2 to 19-20 represent the distal to proximal coronary sinus recordings; MAP 1-2 represents the electrograms of the ablation catheter; and EPI 1-2 to 7-8 represent the distal-to-proximal recordings of the small electrode catheter. CS = coronary sinus; E-QRS = electrograms-QRS; PCL = pacing cycle length; PPI = postpacing interval; S-QRS = stimulus-QRS; TCL = tachycardia cycle length.

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  Figure 2. A: Tracing during manifest entrainment by pacing delivered from the MAP catheter placed on the opposite side of the epicardial earliest activation site (epi-EAS) is presented. The asterisks indicate the electrograms captured by the last pacing stimulus, occurring at the cycle length of 380 ms. The distal electrograms of the small microelectrode catheter (EPI 1-2 and 2-3) are orthodromically captured with long conduction intervals via the slow conduction zone (SCZ) (red asterisks), while the paroxysmal electrograms are antidromically captured (green asterisks). The presence of the SCZ between the pacing site and epi-EAS (orthodromic capture site) was suggested. B: Estimated ventricular tachycardia (VT) circuit is shown with a white arrow. Given the limited mapping and unknown captured area during entrainment pacing, it is also possible that the VT circuit is completely midmyocardium/epicardium. CS = coronary sinus; PCL = pacing cycle length; PPI = postpacing interval; RFCA = radiofrequency catheter ablation; TCL = tachycardia cycle length.

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  Figure 3. A: The fluoroscopic positions and local electrograms were compared between the initial radiofrequency catheter ablation (RFCA) site and successful RFCA site. Abnormal, low-amplitude, fractionated electrograms preceding the QRS were observed at the initial RFCA site. However, we did not record such abnormal potentials at the successful RFCA site. B: The anatomical position projected by the CARTO activation map (Biosense Webster, Diamond Bar, CA) showed that the successful RFCA site was inferior and lateral to the left ventricle and 38 mm remote from the initial RFCA site. INF = inferior; LAO = left anterior oblique; RAO = right anterior oblique; RFCA = radiofrequency catheter ablation.