How is pathophysiology of MR?

• The resistance to LV emptying (LV afterload) is reduced in patients with MR as a consequence, the LV is decompressed into the LA during ejection, and with the reduction in LV size during systole, there is a rapid decline in LV tension. • The initial compensation to MR is more complete LV emptying. However LV volume increases progressively with time as the severe of the regurgitation increases and as LV contractile function deteriorates. • This increase in LV volume is accompanied by a reduced forward CO. LV compliance is often increased, and thus, LV diastolic pressure does not increase until late in the course， • The regurgitant volume varies directly with the LV systolic pressure and the size of the regurgitant orifice; the latter, in turn, is influenced by the extent of LV and mitral annular dilation. Because EF rises in severe MR in the presence of normal LV function, even a modest reduction in this parameter (<60%) reflects significant dysfunction