PMC8084376_01
A, B. Biplane transesophageal echocardiography, mid-esophageal view. An echogenic multilobulated mass (asterisk), in the fluid-filled left pulmonary artery recess of the pericardial transverse sinus mimics a thrombus in the left atrial appendage (LAA); C. Transesophageal echocardiography, mid-esophageal view. The true LAA lumen is in continuity with the left atrium (LA) and appears collapsed by surrounding echogenic tissue (asterisk); D. Reconstruction of a transversal contrast-enhanced cardiac computed tomography in the same orientation as in panel C. The collapsed LAA lumen (arrow) does not contain any intraluminal mass. Posteriorly, the left pulmonary artery recess of the transverse pericardial sinus is filled with an isodense material compatible with fluid surrounded by hypodense epicardial fat; Ao : aorta; LSPV : left superior pulmonary vein; TS : left pulmonary artery recess of the transverse pericardial sinus.
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Right next to the left atrium, an echogenic, multilobulated, partially mobile mass, similar to the one previously reported, was visualized (Fig. 1A, B; Suppl. By slightly rotating the TEE probe the true LAA lumen was found, thrombus-free, but collapsed by an echogenic mass (Fig. 1C; Suppl. Computed tomography (CT) showed a thin tubular thrombus-free LAA lumen surrounded by isodense fluid in the left pulmonary artery recess of the transverse pericardial sinus and by hypodense epicardial fat (Fig. 1D).