a diastolic murmur, similar to that of mitral stenosis, heard best at the cardiac apex in some cases of free aortic insufficiency; it is thought to be caused by the turbulent regurgitating stream from the aorta mixing into the stream simultaneously entering from the left atrium through the mitral valve, causing posterior movement of the anterior leaflet of the mitral valve with transient acceleration of blood flow through the mitral valve. SYN: Austin Flint murmur.