Platypnea orthodeoxia syndrome in a patient with patent foramen ovale and normal atrial pressure. Case report and presentation of underlying pathophysiological mechanisms.

Platypnea-orthodeoxia Syndrome is characterized by clinically significant postural hypoxia. The full spectrum of the syndrome includes intracardial and extracardial abnormalities with R->L shunt. Various concurrent underlying physiological abnormalities are usually encountered that require thorough clinical and laboratory evaluation. A high clinical suspicion in patients with unexplained dyspnea is also required to reach a firm diagnosis. We herein present a rare case of an 82-years-old patient with episodic unexplained dyspnea, patent foramen ovale with normal pulmonary pressures and we review the underlying physiologic mechanisms.