• 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.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021
• A rare congenital abnormality of the heart characterized by the presence of three atria. The right or left atrium is divided into two parts by fibromuscular tissue or a membrane. It may be associated with other heart congenital abnormalities.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• The presence of an additional membrane in the left or right cardiac atrium which results in the subdivision of the affected atrium (and thus in total three atria, whence the name).
  Human Phenotype Ontology (HPO)
  The Human Phenotype Ontology Project, 2021
• First reported in 1868, cor triatriatum, that is, a heart with 3 atria (triatrial heart), is a congenital anomaly in which the left atrium (cor triatriatum sinistrum) or right atrium (cor triatriatum dextrum) is divided into 2 compartments by a fold of tissue, a membrane, or a fibromuscular band. Classically, the proximal (upper or...
  Medscape
  WebMD, 2019
• Cor triatriatum is an extremely rare congenital (present at birth) heart defect. The human heart normally has four chambers, two ventricles and two atria. The two atria are normally separated from each other by a partition called the atrial septum and the two ventricles by the ventricle septum. In cor triatriatum there is a small extra...
  NIH Genetic and Rare Diseases
  National Center for Advancing Translational Sciences