How do you measure mitral regurgitation on an echocardiogram (echo)?

How to Measure Mitral Regurgitation on Echocardiography

Measure mitral regurgitation severity by integrating multiple quantitative and qualitative echocardiographic parameters rather than relying on any single measurement, using transthoracic echocardiography as the primary modality with transesophageal echocardiography or cardiac magnetic resonance when findings are inconclusive. 1

Primary Imaging Modality Selection

• Transthoracic echocardiography (TTE) is the first-line imaging test for assessing MR mechanism and severity 1
• Transesophageal echocardiography (TEE) should be performed when TTE provides insufficient anatomic detail, when severity assessment is internally inconsistent, or when guiding transcatheter interventions 1
• Cardiac magnetic resonance (CMR) is recommended when echocardiographic assessment remains uncertain or when echocardiographic and clinical findings are discordant 1

Step 1: Determine the Mechanism of MR

Valve Morphology Assessment

• Evaluate mitral valve leaflets in multiple views (parasternal long-axis, apical four-chamber, apical two-chamber) to identify primary versus secondary MR 1
• For degenerative (primary) MR, measure flail gap in the view where it appears largest (parasternal long-axis, four-chamber, or five-chamber), with ≤10 mm gap recommended for repair 1
• Measure flail width in transgastric short-axis view where the flail width is largest, with ≤15 mm width recommended for repair 1
• For functional (secondary) MR, measure coaptation depth in the four-chamber view where it is greatest and coaptation length where it is shortest 1

Common Pitfall to Avoid

• Do not misinterpret anterior leaflet override as prolapse in secondary MR—in true prolapse, the leaflet moves superiorly beyond the mitral annular plane into the left atrium, whereas in secondary MR with LV dysfunction, both leaflets remain tethered into the ventricle throughout systole 1, 2

Step 2: Quantify MR Severity Using Multiple Parameters

Quantitative Parameters (Primary Measurements)

Effective Regurgitant Orifice Area (EROA)

• Measure using the proximal isovelocity surface area (PISA) method in two orthogonal planes (parasternal long-axis and apical four-chamber views) 1
• Optimize color Doppler settings: adjust color gain and scale, reduce sector size to maximize frame rate, and expand the zone using zoom function 1
• Identify all three components of the regurgitant jet: vena contracta, PISA, and jet into the left atrium 1
• Use cine-loop to find the best frame for measurement at peak systole 1

Vena Contracta Width

• Measure the narrowest portion of the regurgitant jet immediately distal to the regurgitant orifice, perpendicular to the jet direction 1
• Parasternal long-axis view is preferred for measurement; use apical four-chamber if parasternal view is unavailable 1
• Measure in two orthogonal planes to account for asymmetric jets 1

Regurgitant Volume (RVol) and Regurgitant Fraction (RF)

• Calculate RVol and RF as percentages of MR volume relative to total LV stroke volume 1
• Recognize that these values interact in complex ways: a given EROA can have different RVol depending on driving velocity and MR duration, and a given RVol can have different RF depending on LV size and function 1

Critical Consideration for Secondary MR

• In secondary MR, a given EROA or RVol can be disproportionately severe or not severe depending on LV end-diastolic volume and ejection fraction—proportionate assessment is essential 1

Qualitative and Supportive Parameters

Color Doppler Jet Assessment

• Optimize color gain and scale before evaluating jet characteristics 1
• Evaluate jet area and length in multiple views, recognizing these are affected by aortic-to-LV pressure gradient and LV compliance 1
• Note that color jet parameters alone are not recommended to quantitate severity but serve for initial detection 1

Continuous Wave Doppler

• Assess MR jet density and contour to support severity grading 1
• Recognize non-holosystolic patterns: early systolic, late systolic, or biphasic MR can significantly affect volume calculations 1

Pulmonary Vein Flow

• Evaluate for systolic flow reversal in pulmonary veins, which indicates severe MR 3
• Late systolic backward flow in pulmonary veins is highly specific for fourth-degree (severe) MR 3

Step 3: Assess Hemodynamic Consequences

Left Ventricular Assessment

• Measure LV end-diastolic and end-systolic dimensions to assess ventricular compensation 1
• Calculate LV ejection fraction using biplane Simpson's method or 3D echocardiography 1
• Severe chronic MR is unlikely if LV and LA examination findings are normal, even if echocardiography suggests otherwise 4, 2

Left Atrial Assessment

• Measure LA size and volume to assess chronicity and severity 1
• Evaluate for systolic turning flow (STF) of the MR jet within the LA cavity, present in most patients with third- and fourth-degree MR 3

Step 4: Integrate Findings for Final Severity Grading

Integration Principle

• All guidelines recommend using quantitative parameters together with qualitative parameters to define MR as mild, moderate, or severe 1
• This integration minimizes measurement errors for each individual parameter and ensures internal consistency 1

When Findings Are Discordant

• If TTE data are internally inconsistent or conflict with clinical presentation, perform TEE or CMR 1
• TEE is excellent for defining mechanism but can underestimate severity due to sedation or anesthesia effects 1
• CMR provides more reproducible quantitative measurements of RVol, RF, LV volumes, and LVEF 1

Special Consideration for Late Systolic MR

• When physical examination shows only a very late soft systolic murmur without diastolic filling sounds, echocardiography frequently overestimates severity by not accounting for the short duration of late systolic regurgitation 4, 2
• Conversely, when physical examination suggests severe MR but echocardiography shows only mild regurgitation, the echocardiogram likely underestimates severity due to technical limitations with eccentric jets 4

Advanced Techniques

Three-Dimensional Echocardiography

• 3D TEE provides superior anatomic detail for valve morphology and is essential for guiding transcatheter interventions 1
• 3D color Doppler allows direct measurement of vena contracta area and PISA, which may be more accurate than 2D methods for asymmetric jets 1, 5
• 3D assessment is particularly valuable for functional MR with eccentric jets 1

Specific Measurements for Intervention Planning

• Mitral valve opening area ≥4 cm² is recommended for repair candidacy 1
• Leaflet thickness ≤5 mm is recommended 1
• Absence of considerable annular calcification, marked valvular cleft, leaflet perforation, or marked posterior leaflet restriction should be confirmed 1