Platypnea orthodeoxia syndrome after recent stroke: A case report of a sandwiched right atrium

Background: Platypnea orthodeoxia syndrome (POS) is a condition characterized by onset or worsening of dyspnoea and desaturation in upright position that is relieved by returning to a supine position. This case report illustrates a sudden onset of severe platypnea caused by compression of the right atrium (RA) due to aortic dilatation and unilateral diaphragmatic paralysis after a recent stroke. Case summary: A 71-year-male patient with a medical history of recent stroke of the left hemisphere was referred to emergency department with acute dyspnoea. During observation in the emergency department, desaturation was noted in upright position. A contrast computed tomography excluded pulmonary embolism but revealed a dilated aortic root and an elevated right hemidiaphragm. The RA was compressed between these two structures (sandwiched). Given the clinical suspicion of a POS, a transoesophageal echocardiography was performed which confirmed the presence of a persistent foramen ovale (PFO) in supine position. In upright position, there was a torrential increase in right-to-left shunting. The PFO was closed using an Occlutech™ device. Directly after the procedure, the patient was symptom free. Discussion: A rise in RA pressure or difference in flow pattern in the RA can make a PFO become symptomatic. Elevated RA pressure was ruled out. Most anatomical pathologies influencing the flow pattern develop slowly over time. This case shows a presentation of POS after a recent stroke possible due to change in anatomy because of right hemidiaphragm paralysis in combination with the aortic dilatation