Third Atrial Chamber

Abstract

A 10-MONTH-OLD BOY (weight: 5.8 kg; height: 66 cm; body mass index: 13) was taken to the cardiac catheterization laboratory before the creation of a bidirectional Glenn shunt. At 4 days of age, transthoracic echocardiography done for the evaluation of persistent cyanosis revealed heterotaxy (left atrial isomerism), situs ambiguous with levocardia, bilateral superior vena cava, atrial septal defect (9 mm), partial anomalous right pulmonary venous return to the morphologic right atrium, discordant atrioventricular connection and concordant ventriculoarterial connection, with a hypoplastic right ventricle. The child underwent stenting of the patent ductus arteriosus and balloon atrial septostomy on the 11th day of life. Pulmonary artery banding was done at the age of 1 month. During the current admission, a computerized tomography scan revealed the complex connections of the great vessels (Fig 1). A 4-chamber transesophageal echocardiography view displayed the morphologic left atrium, which was on the right side, and multiple coronary artery fistulae opening into an enlarged chamber located superiorly (Fig 2; Video 1). The atrial septal defect could be visualized in the bicaval view (Fig 3; Video 2). A modified midesophageal 4-chamber view displayed a large superior chamber, as well as the atrial septal defect (Fig 4). Agitated saline was injected into a right upper extremity vein. The agitated saline appeared first in the right internal jugular vein and then appeared in the upper atrial chamber, right side atrium (morphologic left atrium), followed by an appearance in the right ventricle (Fig 5, A-D; Video 3). Slight retraction of the probe from the 4-chamber view displayed a right superior vena cava on the right side that was moving into close juxtaposition with the morphologic left atrium (Fig 6; Video 4). Correlation with computerized tomography findings revealed the identity of the structure seen by transesophageal echocardiography into which the right superior vena cava and the coronary artery fistulae were draining. What is the diagnosis? Fig. 2(A) Midesophageal 4-chamber 2-dimensional transesophageal echocardiography image with (B) color Doppler displaying an enlarged chamber (white query sign) with multiple coronary artery fistulae opening into the chamber. mLA, morphologic left atrium; RV, right ventricle; TV, tricuspid valve View Large Image Figure Viewer Download Hi-res image Fig. 3Bicaval midesophageal transesophageal echocardiography view displaying the atrial septal defect. View Large Image Figure Viewer Download Hi-res image Fig. 4Midesophageal 4-chamber 2-dimensional transesophageal echocardiography image with color-flow Doppler displaying the atrial septal defect and a large upper chamber marked by white query sign. View Large Image Figure Viewer Download Hi-res image Fig. 5Midesophageal 4-chamber 2-dimensional transesophageal echocardiography image displaying (A) the agitated saline echo contrast injected into an upper limb vein entering the right superior vena cava, (B) the coronary sinus and the morphologic right atrium on the right side, (C) the morphologic left atrium on the right side, and (D) the right ventricle. View Large Image Figure Viewer Download Hi-res image Fig. 6Midesophageal 4-chamber 2-dimensional transesophageal echocardiography image displaying the right superior vena cava and morphologic right atrium in close proximity. ASD, atrial septal defect; LAA, morphologic left atrial appendage; mLeft atrium, morphologic left atrium; mR, morphologic right atrium; RSVC, right superior vena cava; RV, right ventricle; TV, tricuspid valve. View Large Image Figure Viewer Download Hi-res image