Clear morphological depiction of cor triatriatum in a child by transthoracic 3-dimensional echocardiography.

A 3-year-old boy had a history of cor triatriatum, which was diagnosed incidentally when he was 1 year old during workups for failure to thrive and funnel chest. Initial echocardiographic evaluation revealed no evidence of obstruction through the orifice (mean pressure gradient, 3 mm Hg). However, progressive flow obstruction was noted at follow-up. At 3 years of age, 2-dimensional echocardiogra-phy at the apical 4-chamber view demonstrated a membrane-like structure traversing the left atrium (LA) (Figure 1A; see Movie I in the online-only Data Supplement). Doppler echo-cardiography revealed a mean pressure gradient of 8.9 mm Hg across the orifice of this membrane (Figure 1B). However, depiction of the relationships between this membrane and the surrounding structures was not clear. Therefore, trans-thoracic 3-dimensional echocardiography (3DE) was performed (iE33; Philips, Andover, MA) with an X-7 matrix array transducer. The 3DE images cropped from the posterior and superior aspects of the LA toward the atrioven-tricular groove clearly showed that this membrane extended from the fossa ovalis area of the atrial septum to the LA free wall (Figure 2A; see Movie II in the online-only Data Supplement). Therefore, the LA was divided into 2 chambers (Figure 2B; see Movie III in the online-only Data Supplement). The communication between these 2 chambers was through a single, relatively small, horseshoe-shaped orifice , which was located near the atrial septum (Figure 2A; see Movie II in the online-only Data Supplement). Pulmonary veins connected to the posterior superior chamber (Figure 2A). In addition, a small secundum-type atrial septal defect was found within the anterior inferior chamber , which connected to the mitral valve (Figure 2C). Color 3DE further confirmed the location and size of this orifice, which was ≈0.43 cm 2 in area (Figure 2D; see Movie IV in the online-only Data Supplement). Multidetector computed tomography showed similar findings (Figure 3A and 3B). Cardiac catheterization revealed a pressure gradient of 12 mm Hg across the cor triatriatum (pulmonary artery wedge pressure, 15 mm Hg; mean left atrial pressure, 3 mm Hg). The patient underwent surgery for excision of cor triatriatum, repair of the atrial septal defect, tricuspid valve plasty, and correction of the funnel chest 4 months later. He had an uneventful perioperative course. Postoperative echo-cardiography showed complete excision of the membrane. Cor triatriatum is a rare congenital cardiac anomaly accounting for 0.1% to 0.4% of all cardiac defects. 1 The LA is divided into 2 chambers by an …