Epicardial and Endocardial Validation of Conduction Block After Thoracoscopic Epicardial Ablation of Atrial Fibrillation

Figures

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  Fig. 1. Electrophysiological validation. Upper part: Endocardial Carto voltage maps (Biosense Webster, cutoffs 0.5 to 1.5 mV) of a posterior and anterior view of the left atrium, showing a low-voltage area in red reflecting the box lesion. The little pink spots represent locations where electrophysiological signals were checked. This voltage map is only shown to present the locations of testing, and voltage maps were not further used for drawing conclusions in the current study. Lower part: Left-sided thoracoscopic views of each location during epicardial testing for bidirectional conduction block using an endocardial His bundle catheter. A, anterior; Ca, caudal; Cr, cranial; LA(A), left atrium (appendage); LIPV, left inferior pulmonary vein; LM, ligament of Marshall; LSPV, left superior pulmonary vein; P, posterior; RIPV, right inferior pulmonary vein; RSPV, right superior pulmonary vein.

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  Fig. 2. Electrophysiological recordings. Paper speed: 25 mm/s. (a) Entrance block: absence of potentials on the epicardially placed catheter. (b) Exit block: absence of conduction from pacing signals. If A and B are confirmed, the endpoint of bidirectional block is met. (c) Absence of entrance block: potentials recorded on the epicardially placed catheter. (d) Absence of exit block: conduction from pacing signals. If C or D is observed, the endpoint of bidirectional block is not met. Epi, epicardial testing using a His bundle catheter.

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  Fig. 3. Results of testing for bidirectional conduction block. This posterior view of the left atrium shows the number of confirmed bidirectional conduction block in relation to the number of tested areas. Also, the percentage of similarity between epicardial and endocardial testing, and between endocardial testing and the correct estimation of the surgeon is shown. Endo, endocardial bidirectional block; Epi, epicardial bidirectional block; Equal, corresponding epicardial and endocardial conduction block; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; RIPV, right inferior pulmonary vein; RSPV, right superior pulmonary vein; Surgeon, correct estimation of the surgeon if bidirectional block is present or not, based on a conductance graph given by the epicardial ablation device.