Platypnea-Orthodeoxia Syndrome Due to Venovenous Malformation

The platypnea-orthodeoxia syndrome (POS) is a rare clinical condition characterized by dyspnea occurring in the upright position and relieved in the supine position (platypnea) associated with oxygen desaturation noted in the upright position (orthodeoxia).1 A diagnosis of POS requires two of the following criteria: 1) orthodeoxia, 2) platypnea, 3) presence of an interatrial communication, 4) right-to-left shunt, and 5) absence of pulmonary arterial hypertension or right atrial hypertension.1,2 POS can originate in the heart, lungs, abdomen, or elsewhere due to either an intracardiac (cardiac POS) or intrapulmonary shunt, or a ventilation-perfusion mismatch.1 However, a venovenous malformation (VVM) as a cause of cardiac POS has never been reported in the literature.1 We report here the case of a 24-year-old female patient who presented with cardiac POS due to a VVM. The syndrome emerged insidiously 16 years after an extracardiac total cavopulmonary connection (TCPC) for a complex of congenital cardiovascular malformations and was successfully treated with percutaneous transvenous coil embolization.