Definition: A malformation of the heart in which the embryonic common PULMONARY VEIN was not incorporated into the LEFT ATRIUM leaving behind a perforated fibromuscular membrane bisecting the left atrium, a three-atrium heart. The opening between the two left atrium sections determines the degree of obstruction to pulmonary venous return, pulmonary venous and pulmonary arterial hypertension.
Other names Triatrial Heart; Triatrial Hearts; Subdivided Left Atriums; Left Atriums, Subdivided; Left Atrium, Subdivided; Hearts, Triatrial; Heart, Triatrial; Atriums, Subdivided Left; Atrium, Subdivided Left; Subdivided Left Atrium; Cor Triatriatum Sinistrum
