Exercise-induced Right-to-left Shunt in a Patient with Combined Pulmonary Fibrosis and Emphysema.

Combined pulmonary fibrosis and emphysema (CPFE) is characterized by emphysematous lesions in the upper lung field and pulmonary fibrosis in the lower lung field and is often associated with pulmonary hypertension and severe exercise-induced hypoxemia (EIH). We herein report a 62-year-old man with CPFE who presented with severe EIH despite relatively preserved lung volumes. Cardiopulmonary exercise testing suggested exercise-induced right-to-left shunt (EIS) through a patent foramen ovale (PFO). EIS was attributed to exercise-induced pulmonary hypertension. In this case report, we highlight the possibility of EIS using PFO for CPFE. We also discuss potential treatments including pharmaceutical interventions and PFO closures.