Three's a Crowd - An Extremely Rare Case of Cor Triatriatum Dexter.

Introduction: Cor triatriatum is a congenital cardiac anomaly in which the left (sinister) or right (dexter) atrium is divided into two compartments by residual embryonic tissue, resulting in a tri-atrial heart. As cor triatriatum dextrum can present clinically in various ways and have multiple associated cardiac anomalies, this report attempts to contribute to what is known about this exceedingly rare disorder.

Case: A 40 year old Hispanic man with a medical history of gastritis presented with complaints of palpitations, dizziness and bilateral lower extremity edema. He was found to have atrial fibrillation and new onset heart failure. The patient was admitted for rate control and further evaluation, which revealed several cardiac anomalies. Initial 2D echocardiography demonstrated severe right atrial enlargement, right ventricular hypertrophy and an engorged coronary sinus, which prompted further assessment of the patient's cardiovascular anatomy. Transesophageal echocardiography (TEE) revealed a severely enlarged, septated right atrium with a possible unroofed coronary sinus and a small patent foramen ovale (PFO). Left- and right-heart catheterization established a coronary-cameral fistula between the right coronary artery (RCA) and right atrium, as well as left-to-right shunt. The patient improved clinically with conservative management including diet modification, furosemide and digoxin for fluid and rate control, and was referred to cardiothoracic surgery for further evaluation.

Discussion: Cor triatriatum dextrum is an extremely rare cardiac condition: In high-volume echocardiographic laboratories, prevalence is less than 0.01 percent. This case highlights the association between cor triatriatum and other congenital cardiac anomalies, including persistent left superior vena cava with an unroofed coronary sinus, PFO and left-to-right shunt; all of which were found in this patient. While cases of cor-triatriatum sinistrum often require correction in infancy (due to left sided heart failure, pulmonary edema and cyanosis), cor-triatriatum dextrum is sometimes diagnosed in adulthood due to the lack of left heart and pulmonary involvement.