Cor triatriatum is an uncommon but surgically correctable cause of pulmonary venous hypertension and congestive cardiac failure, with a reported incidence of 0.1% among children with congenital heart diseases. Association with partial atrioventricular canal defect (PAVCD) is even rarer, with only anecdotal reports appearing in the literature. In the classic form, cor triatriatum is characterized by the presence of a fibromuscular diaphragm that subdivides the left atrium into a proximal accessory chamber and a distal true chamber.
Dr. Praveen Varma, Warrier, G., Ramachandran, P., Neema, P. Kumar, Manohar, S. Rema Krish, Titus, T., and Neelakandhan, K. Sankaran, “Partial atrioventricular canal defect with cor triatriatum sinister: report of three cases”, The Journal of thoracic and cardiovascular surgery, vol. 127, no. 2, pp. 572–573, 2004.