Cardiac Paroxysmal Orthodeoxia Syndrome: A comprehensive process of this challenging disease starting from the clinical suspicion till the therapeutic procedure.

BACKGROUND: The platypnea-orthodeoxia syndrome is a rare disorder characterized by both dyspnea and arterial desaturation in the upright position that is relieved by returning to a recumbent position. In addition to PFO (as discussed in our case) and other interatrial defects, this syndrome has also been described with intrapulmonary shunting and with disorders such as pericardial effusion, constrictive pericarditis, emphysema, amiodarone pulmonary toxicity, pneumonectomy, and cirrhosis.

METHODS: We describe a case of platypnea-orthodeoxia syndrome (POS) due to patent foramen ovale (PFO) occurring during the preoperative evaluation of an elderly patient who presented to the emergency department for a femoral neck fracture. Initial evaluation was shifted to a pulmonary embolism or COVID-19 infection that were excluded by a chest CT with IV contrast and RT-PCR for COVID-19. 12-leads ECG and TTE were unremarkable.

RESULTS: During hospital stay, the patient complains of positional dyspnoea that develops upon sitting up, accompanied with refractory hypoxaemia that reverts on recumbent position. Following a high clinical suspicion of POS, a bubble contrast echocardiogram was performed and showed important patent foramen ovale (PFO) highlighted by an abundant passage of contrast from the right atrium to the left associated with hyperdynamic interatrial septum. An urgent percutaneous closure was performed, and marked improvement of patient's symptoms has been noted since then.

CONCLUSION: The diagnosis of POS has been challenging especially during the current pandemic. Our case emphasizes on the importance of a detailed history and physical exam, the role of multimodality imaging techniques to diagnose POS and the high success rate of percutaneous methods for PFO closure.