Platypnea orthodeoxia Syndrome is WHAT?

DD Berg et al NEJM:380, p 1360 April 4, 2019 presented an interesting case of Positional Shortness of Breath or The Platypnea orthodeoxia syndrome. This refers to the situation where patients are short of breath sitting (with hypoxia) and feel relief on lying down. “Platy” is for “flat” as in “plate”. The Platypnea orthodeoxia syndrome occurs in right to left shunts at the atrial level. Usually blood flows from the superior vena cava (SVC) toward the anterior right atrial (RA) wall and from the inferior VC to the posterior RA wall. Anything that alters the shape of the RA, such as an aortic aneurysm, a loculated effusion, or severe pulmonary disease can redirect flow toward the interatrial septum and across a patent foramen ovale. It can also happen in tricuspid regurgitation when the regurgitant jet is directed to the interatrial septum as in the case Berg presented.