Cor polyatriatum: a very rare and original variant of cor triatriatum.

Cor triatriatum sinister is a rare congenital heart defect in which the left atrium is classically partitioned into a proximal and distal chamber by a fibromuscular membrane. The proximal chamber receives blood from the pulmonary venous circulation and communicates with the distal chamber through fenestrations in the membrane. A trans-membrane blood flow obstruction can lead to pseudo-mitral stenosis or pulmonary venous hypertension, among other clinical pathways. Herein, we report the first case in the literature of 'cor polyatriatum', where a primary fibromuscular membrane along with two additional branching membranes leads to a total of five atrial chambers.