2D echocardiographic image of the apical long-axis view from a patient with mitral stenosis after percutaneous transluminal mitral commissurotomy (PTMC): note that with mitral valve opening improved, SEC is not evident in the left atrium (LA). View Video 6 at http://movie-usa.glencoesoftware.com/video/10.1530/ERP-18-0083/video-6.