PLATYPNEA-ORTHODEOXIA SYNDROME DUE TO A BIDIRECTIONAL SHUNT

Abstract

SESSION TITLE: Medical Student/Resident Cardiovascular Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Platypnea-orthodeoxia syndrome is a rare disorder characterized by dyspnea and arterial desaturation in an upright position with improvement in the supine position (1). Our case highlights a known but rather uncommon and reversible cause of hypoxia which can potentially be misdiagnosed. CASE PRESENTATION: A 62-year-old male with a history of hypertension and type 2 diabetes mellitus presented to the emergency department with gradual, progressive, intermittent, dyspnea for 2 months, which was worse with standing and walking, and better after laying flat. The patient stated that he used to walk a few miles without any discomfort approximately one year ago. But now the dyspnea had limited his ability to walk less than one block. As per records, the patient had a cardiac catheterization 1 month back for an abnormal stress test and it showed angiographically normal coronaries and 60% ejection fraction. No recent sick contacts and no family history of cardiac conditions. Vitals on presentation revealed tachycardia, respiratory rate of 20/min, 99% O2 saturation on lying flat, and 84% on standing up which dropped to 78% after walking 10 steps. The hypoxia while standing up didn't resolve with nasal cannula oxygenation. Labs were within normal limits. Chest X-ray showed normal lung fields and normal heart shadow, CT pulmonary angiogram was normal. 2D Echocardiography with a bubble study showed a left ventricular ejection fraction of 55 % and a patent foramen ovale (PFO). Transesophageal echocardiography (TEE) showed large atrial septal defect with left-to-right shunting and no right-to-left shunting. The patient was scheduled to undergo surgical closure of the defect. DISCUSSION: PFO was found in 25 to 30 percent of individuals in an autopsy study and a community-based transesophageal echocardiography (TEE) study (2). Two required components of a PFO are an interatrial shunt or an intrapulmonary shunt as in the hepatopulmonary syndrome, and a functional component that promotes abnormal shunting when the patient rises from a recumbent to an upright position. Our patient had both these components due to a left to right shunt. CONCLUSIONS: Platypnea-orthodeoxia syndrome can be presented as mere dyspnea on effort. A clinician should check the positional change of symptoms and/or oxygenation when he or she sees a patient with dyspnea on effort of undetermined origin. Preexisting bidirectional shunting precipitated in its right-to-left component by Valsalva maneuver, coughing, or straining might explain the occurrence of a paradoxical embolism in Secundum atrial septal defect patients(3). Definitive treatment in the form of closure is recommended in such cases. Reference #1: 1. Cheng TO. Platypnea-orthodeoxia syndrome: etiology, differential diagnosis, and management. Catheter Cardiovasc Interv. 1999;47(1):64-66. https://doi.org/10.1002/(SICI1522-726X(199905)47:1<64::AID-CCD15>3.0.CO;2-6) Reference #2: 2. Hagen PT, Scholz DG, Edwards WD. Incidence and size of patent foramen ovale during the first 10 decades of life: an autopsy study of 965 normal hearts. Mayo Clin Proc. 1984;59(1):17-20. https://doi.org/10.1016/s0025-6196(1260336-x) Reference #3: 3. Rigatelli G, Dell'avvocata F, Tarantini G, Giordan M, Cardaioli P, Nguyen T. Clinical, hemodynamic, and intracardiac echocardiographic characteristics of secundum atrial septal defects-related paradoxical embolism in adulthood. J Interv Cardiol. 2014;27(6):542-547. https://doi.org/10.1111/joic.12159 DISCLOSURES: No relevant relationships by Sanya Chandna, source=Web Response No relevant relationships by Monarch Shah, source=Web Response