Left and right atria on transesophageal echocardiography

Recorded in the horizontal (0º) plane, panel A shows the left atrium (LA), right atrium (RA), interatrial septum, tricuspid valve (TV) leaflets, and right upper pulmonary vein (RUPV). Panel B shows normal color Doppler flow (red/orange) of blood entering the LA from the RUPV.