Sometimes related . Mitral valve prolapse is a diagnosis which describes how the valve closes. A heart murmur is a physical finding (sign) it is not a diagnosis. A heart murmur is a sound you can hear when blood flows with turbulence (rough flow like rapids in a river). Murmurs can be caused by many things. The location and quality often gives us clues to what caused it. Prolapse may or may not have a murmur.