Acquired Systemic-to-pulmonary Venous Shunt or Persistent Left Superior Vena Cava? A Rare Right-to-left Shunt Case-based Discussion.

Cardiac shunts are often described in congenital or pediatric populations, but systemic-to-pulmonary venous shunts in adult patients are reported in literature in isolated case reports. We present the case of a 70-year-old female with a left superior vena cava (SVC) draining into the left atrium by the left superior pulmonary vein, with a complete right-to-left shunt of the superior venous circulation caused by a former catheter thrombosis in the right SVC. Diagnosis was suspected after a contrast echocardiography showing an exclusive perfusion of left heart after intravenous injection and confirmed by helical computed tomography with three-dimensional reconstruction. After medico-surgical discussion, a first-line conservative treatment with oxygen therapy was chosen, due to the stability of symptoms and high predicted risk of perioperative mortality. The particularities of this case are that we cannot determine if the origin of this shunt is a latent persistent left SVC becoming symptomatic after the SVC obstruction or an abnormal collateral pathway due to the thrombosis and the unusual indirect communication through a pulmonary vein.