|Valve morphology||Flail leaflets or ruptured papillary muscles are specific for severe MR||Other findings are nonspecific|
|Regurgitant color flow||Easy to use, evaluates spatial orientation of MR jet, differentiates mild versus severe||Subject to technical and hemodynamic variation; can be underestimated with wall-impinging jets; image quality–dependent|
|Vena contracta width||Quick and easy to use; independent of hemodynamic and instrumentation factors; applies to eccentric jets; can differentiate mild versus severe MR||Not applicable to multiple jets; intermediate values require confirmation; small measurement errors can lead to big changes; 2D measure of a 3D structure; limited lateral resolution|
|PISA||Can be applied to eccentric jets (when angle-corrected); not affected by etiology of MR; quantitative; provides both lesion severity (EROA) and volume data (RVol); flow convergence at Nyquist limit of 50–60 cm/s alerts reader to significant MR||Not valid with multiple jets; provides peak flow and maximal EROA; interobserver variability; errors in radius measurement are squared; multiple potential sources of measurement error|
|Flow quantitation—PW||Quantitative; valid in multiple jets and eccentric jets; provides both lesion severity (EROA, RF) and volume data (RVol)||Time consuming; measurement of flow at MV annulus less reliable with calcified MV and/or annulus; not valid with concomitant significant AR unless pulmonic site is used; requires measurement at multiple sites, which introduces errors|
|Jet profile—CW||Simple, readily available; easy assessment of MR timing||Qualitative; complementary data; complete signal difficult to obtain in eccentric jet; gain dependent|
|Peak mitral E velocity||Simple, readily available, A-wave dominance excludes severe MR||Influenced by LA pressure/compliance, LV relaxation, MV area, and AF; complementary data only, does not quantify MR severity|
|Pulmonary vein flow||Simple; systolic flow reversal is specific for severe MR||Influenced by LA pressure, AF; not accurate if MR jet directed into the sampled vein; absence does not rule out severe MR|
|LA and LV size||Enlargement sensitive for chronic severe MR, important for outcomes; normal size virtually excludes severe chronic MR||Enlargement seen in other conditions (nonspecific); may be normal in acute severe MR|
AF = atrial fibrillation; AR = aortic regurgitation; CW = continuous wave; EROA = effective regurgitant orifice area; LA = left atrium; LV = left ventricle; MR = mitral regurgitation; MV = mitral valve; PISA = proximal isovelocity surface area; PW = pulsed wave; RF = regurgitant fraction; RVol = regurgitant volume.
Described in detail in the 2017 American Society of Echocardiography Guidelines for Assessment of Native Valve Regurgitation (3).