Explain Acute MR Murmur in heart dieases?

MR due to ruptured papillary muscle, ruptured chordae tendinae, or due to Infective Endocarditis/Myocardial infarction.

Characteristic: A systolic murmur is heard at apex, at times parsystolic and other times it diminished or increases in amplitude in late systole. It may radiate to the base and hence confuse with murmur of AS when it is due to rupture of posterior papillary muscle or its chordae tendinae. If anterior papillary muscle ruptures, it radiates to the back. The intensity of murmur doesn't bear any relation to the severity of MR.

Acute MR murmurs may have S, associated, which is rare in chronic rheumatic MR. These murmur of MR increases with increase in peripheral vascular resistance as the flow across aorta is impeded due to increased resistance, thereby enhancing flow via the regurgitant outlet. Thus, handgrip exercise and squatting which increase the PVR, makes MR murmur loud (as against systolic ejection murmur of AS which gets softer). Amy1 nitrite, by reducing PVR softens MR murmur.