Reversible Orthodeoxia

Excerpt

To the Editors: The case reported by Adolph and colleagues (1) of orthodeoxia-platypnea caused by pericardial effusion-related right-to-left atrial shunting is unusual. Right-to-left shunting through a patent foramen ovale is usually associated with spontaneous (2) or induced (3) pulmonary hypertension. In the absence of pulmonary hypertension and, therefore, in the absence of a right-to-left pressure gradient, right-to-left atrial shunting is caused by preferential redirecting of flow from the inferior vena cava toward the patent foramen ovale.

A persistent eustachian valve can cause (in addition to pericardial effusion, which results in an anatomic distortion of the right atrium) interatrial right-to-left shunting