Cavopulmonary window: case report of an unusual variant of a sinus venosus defect

Introduction Isolated partial anomalous pulmonary venous return (PAPVR) with intact atrial septum is a rare finding. A cavopulmonary window is a side-to-side veno-venous communication of the right upper pulmonary vein with the superior vena cava which in its course retains connection to the left atrium. Case presentation We present a case of this unusual variant of a sinus venosus defect far from the atrial roof. Haemodynamic significance of the shunt was confirmed by enlargement of right heart cavities, elevation of pulmonary artery pressure, and significant left-to-right shunting using multimodality cardiac imaging (transoesophageal echocardiography, cardiac magnetic resonance imaging, and right heart catheterization). The defect has been successfully repaired using minimally invasive axillary thoracotomy. Discussion Partial anomalous pulmonary venous return prevalence is low and about 0.4-0.7% in autopsy series of patients with congenital heart disease. This patient's unusual variant of a sinus venosus defect with a window between a pulmonary vein and the superior vena cava far from the atrial roof shows that a sinus venosus defect is not a true atrial septum defect. Left-to-right shunting generally increases with age. Usually, surgical treatment is considered in cases of significant left-to-right shunt (Q(p):Q(s) > 1.5-2.0) and right heart dilatation.