The redundant tip of the mitral valve displays great flexibility and bends back into the LVOT to contact the septum. This is seen with great clarity on ICE films. It is this contact that initiates the positive amplifying feedback cycle leading to significant LVOT gradients. View Video 2 at http://movie-usa.glencoesoftware.com/video/10.1530/ERP-15-0002/video-2.