Platypnea-orthodeoxia Syndrome Due to Right Ventricular Inflow Tract Obstruction Caused by an Elongated Ascending Aorta: Usefulness of Three-dimensional Cardiac Computed Tomography Imaging in the Sitting Position

Abstract

An 84-year-old woman presented with dyspnea in the sitting position. Platypnea-orthodeoxia syndrome (POS) was suspected based on arterial desaturation when her posture changed from the supine to the sitting position. Transesophageal echocardiography showed right-to-left shunting enhancement through a patent foramen ovale (PFO) in the sitting position. Three-dimensional (3D) cardiac CT in the sitting position revealed that the elongated ascending aorta compressed the right ventricular inflow tract, resulting in restricted blood flow to the right ventricle and increased right-to-left shunting. This case highlights the role of 3D-CT in the sitting position in the management of POS.