Three-month-old male presented with failure to thrive, dyspnoea, and recurrent respiratory infections. Transthoracic echocardiography revealed cor triatriatum sinister with severe obstructed flow between pulmonary veins, mitral valve, and left ventricle through only 2 mm perforation on the fibromuscular membrane and a small patent foramen ovale (type A2 of Lam classification) with a mean Doppler gradient of 12 mmHg.
Due to unclear pulmonary venous drainage of all pulmonary veins, the patient underwent cardiac computed tomography (CCT) examination which showed, in addition to the cor triatriatum, a tortuous dilated left-sided vertical vein (VV) with outflow in the proximal chamber of the left atrium (LA) and cranially in the ectasic innominate vein (IV). The right pulmonary veins drained with independent ostia into the postero-superior collecting chamber while the VV collected the left lung venous drainage, providing a way of decompression for the LA.
The patient underwent successful complete resection of the fibromuscular membrane (M) between the accessory and the true left atrial chambers, reconstruction of the interatrial septum with autologous pericardial patch concomitant with the ligation of the VV proximally to the confluence with the IV. The usual approach through median sternotomy, standard cardiopulmonary bypass with aorto-bicaval cannulation, mild hypothermia, and cardioplegic arrest was performed. The LA was accessed via a right atrium-transseptal approach.
In this case, the use of CCT helped to elucidate the occurrence of complete left pulmonary drainage toward the VV, thus explaining the substantial left–right shunt.
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