Radiopaedia.org

A linear filling defect is present in the left atrium, running between the left lateral wall anterior to the left inferior pulmonary vein ostium and the right anterior wall. This is consistent with cor triatriatum with a large inferior fenestration. All 4 pulmonary veins drain into the posterior chamber of the partially septated LA. The left atrial appendage is in the anterior chamber of the partially septated LA.