Describe Austin Flint Murmur in heart dieases?

The AR jet may impinge on the undersurface of the anterior leaflet of the mitral valve and push it up, thus creating a relative MS. This produces an apical diastolic rumble mimicking MS murmur. This murmur can be differentiated from MS murmur as it is not preceded with an OS and has no presystolic accentuation. Amyl nitrite inhalation, by reducing the peripheral vascular resistance and increasing the peripheral runoff makes the Austin Flint Murmur softer unlike murmur of MS, which becomes louder.