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.