Medical history	Medical history significant for enlargement of right heart cavities with mild elevation of pulmonary artery pressure and mild dyspnoea. Electrocardiogram shows normal sinus rhythm with incomplete right bundle branch block, cardiac auscultation a fixed split of S2.
6 months prior to operation	Transoesophageal echocardiography shows partial reverse flow of the right upper pulmonary vein (RUPV) and evidence of relevant shunt at the level of the superior vena cava (SVC).
	Cardiac magnetic resonance imaging demonstrates a large side-to-side communication (cavopulmonary window) of the RUPV with SVC. The RUPV retains its connection to the left atrium (LA) in its course. Flow measurements show significant left-to-right shunt.
5 months prior to operation	Right heart catheterization shows a jump in the oxygen saturation of the SVC proximal to the cavopulmonary window and confirms significant left-to-right shunting.
Operation	An atrial tunnel patch is inserted through a patent foramen ovale to redirect flow from the RUPV to the LA using minimally invasive axillary thoracotomy.
7 months after operation	Cardiac magnetic resonance imaging demonstrates that the cavopulmonary window is closed with unchanged normal connection of the RUPV to the LA.