Pay Attention! An Unusual Case of Dyspnea

Abstract

Platypnea-orthodeoxia is an uncommon syndrome characterized by dyspnea and hypoxemia in upright position that improves with recumbent position. It can occur due to intracardiac shunts, pulmonary arteriovenous shunts and ventilation perfusion mismatch. We present a unique and rare cause of platypnea-orthodeoxia syndrome. CASE PRESENTATION: A 68 years old man with history of coronary artery disease and COPD presented with acute onset chest pain and associated difficulty breathing. Patient did have several months' history of exertional dyspnea which did not improve with rest this time. On presentation, patient was noted to be hypoxic with oxygen saturation of 88% and ABG showed PH 7.41, PaO2 47 mmHg and PaCO2 22.4 mmHg. Oxygen saturation improved to 94% with 3L of supplemental oxygen. EKG and troponin were unremarkable. CT PE was unremarkable for pulmonary embolism as well. IV heparin drip was started for suspected unstable angina and patient underwent cardiac catheterization that revealed non-obstructive coronary artery disease. Echocardiography showed ejection fraction of 55-60% with mild mitral and tricuspid regurgitationDuring the course of hospitalization, patient was noted to have intermittent positional hypoxemia. He had normal resting saturation on 2 L of oxygen which dropped to 88% sitting upright and dropped to 84% on 2 L of oxygen upon raising both arms. Platypnea-orthodeoxia syndrome was strongly suspected with possible intra-cardiac or intrapulmonary shunt. Meanwhile, CT chest was unremarkable for interstitial lung disease. Right heart catheterization revealed normal right atrial RA (68.9%) and pulmonary arterial PA (68.3%) saturation at rest but reduced RA (42.5%) and PA (43.2%) saturation with sitting up. Echocardiography with bubble study showed right-to-left shunting and trans-esophageal echocardiography revealed a small 0.5 cm atrial septal defect (ASD) with bidirectional shunting. Patient was diagnosed with Platypnea-orthodeoxia syndrome secondary to ASD. He was discharged home on supplemental oxygen and outpatient follow-up for ASD closure.