Double-chambered right ventricle presenting significant outflow tract obstruction only in the right decubitus position.

A 75-year-old man was referred to our echocardiography laboratory for presurgical evaluation. His past history included ventricular septal defect closure. He reported chest discomfort in the right decubitus position. Two-dimensional and Doppler echocardiography revealed an anomalous muscle bundle with accelerated blood flow in the right ventricle. The peak flow velocity of the flow increased from 1.4 m/s in the left decubitus position to 2.9 m/s in the right decubitus position. Double-chamber right ventricle with intermittent mid-ventricular obstruction during the right decubitus position was confirmed by transesophageal echocardiography.