Late emergence of platypnea orthodeoxia: Chiari network and atrial septal hypertrophy demonstrated with transoesophageal echocardiography.

Platypnea orthodeoxia is a rare syndrome that describes breathlessness on standing that resolves on lying flat. We present a previously healthy patient who developed platypnea orthodeoxia in her eighth decade of life. Cardiovascular imaging demonstrated an atrial septal defect, extensive Chiari network and atrial septal hypertrophy. We propose the development of lipomatous atrial septal hypertrophy led to altered atrial compliance and a baffle to direct flow preferentially to the left heart on standing.