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Figure 3 Method used to determine pulmonary vein ostial insertion in the left atrium using intracardiac echocardiography. The dotted line depicts the extrapolated outer left atrial border. Panels A and B represent separate insertion of left and right pulmonary veins, respectively, whereas panels C and D demonstrate a common ostium of the left and right pulmonary veins, respectively. Abbreviations as in Figure 1.