Mitral stenosis echocardiography
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
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Overview
In most cases, the diagnosis of mitral stenosis is most easily made by echocardiography, which shows decreased opening of the mitral valve leaflets, and increased blood flow velocity during diastole. The trans-mitral gradient as measured by Doppler echocardiography is the gold standard in the evaluation of the severity of mitral stenosis.
| Degree of mitral stenosis | Mean gradient | Mitral valve area |
|---|---|---|
| Mild mitral stenosis | <5 | >1.5 cm2 |
| Moderate mitral stenosis | 5 - 10 | 1.0 - 1.5 cm2 |
| Severe mitral stenosis | > 10 | < 1.0 cm2 |
Echocardiographic Assessment
- ECHO is the standard and using various techniques the transmitral flows can be converted to valve areas.
- The MVA can be directly planimetered in some cases.
- ECHO findings also predict the success/failure of balloon valvuloplasty.
- Coexisting valve dysfunction can be identified as well as PHTN and RV dysfunction.
- Cardiac catheterization is a secondary modality used when surgical/percutaneous repair is contemplated or if symptoms are out of proportion to noninvasive testing results.
Mitral valve assessment with echocardiography should include:
- Diagnosis from the pattern of valve involvement and calcification.
- severity of mitral stenosis
- Associated mitral regurgitation
- Other co-existent valve lesions
- Chamber dilatation and function
M-mode echocardiography
M-mode echocardiographic assessment of the valve reveals slow early diastolic closure of the mitral valve. The mid-diastolic closure velocity or E-F slope is remarkably reduced. This can be used to assess the severity of the mitral stenosis and to determine re-stenosis from serial measurements after surgical or percutaneous treatment. E-F slope can also be flat in subjects with normal mitral valve if the left ventricular compliance is reduced.
Another M-mode feature of mitral stenosis is the anterior movement of posterior mitral valve leaflet in early diastole.
2D-Echocardiography
As with any stenotic valve, the main diagnostic feature in the parasternal long axis view is the doming of the anterior mitral valve leaflet in diastole. This is due to the reduced mobility of the valve tips compared to the base of the leaflets.
Thickening of the valve leaflets with or without calcification can be visualized with echocardiography. This can also involve the annulus and the chordae which can be shortened.
Other associated features may include markedly enlarged left atrium, pulmonary hypertension, right heart enlargement and tricuspid regurgitation. There may be involvement of other valves as well.
Orifice area by planimetry
- A well validated technique for assessing severity
- In parasternal short axis view
- The mitral valve is funnel shaped, so the area needs to be measured at the tip of the valves (the narrowest portion).
- Be sure to turn the gain down to have low overall 2D gain.
- Trace the inner edge of the valve orifice during the maximum opening in diastole.
- Not useful if heavily calcified valves or after valvotomy
- Sometimes chordae can mimic the valve orifice.
Doppler echocardiography
Mean transmitral valve gradient
Can be measured by tracing the outline of mitral diastolic inflow and the mean pressure gradient is automatically calculated. The severity can be assessed as mild (<5), moderate (5-10) and severe (>10).
Pressure half time
The rate of pressure decline across the stenotic orifice is determined by the cross sectional area of the orifice. Smaller the orifice leads to slower rate of pressure decline.
Pressure half time is defined as the time interval between maximum early diastolic pressure gradient and the point at which the pressure gradient is half the maximum value.
By echocardiography, this is measured in apical-4-chamber view with continuous wave Doppler aligned with the inflow jet of mitral valve. The spectral trace is recorded and the slope of the flow is measured from the beginning of E-wave ignoring the A-wave.
Based on the Bernoulli equation, the velocity of pressure half time can be derived as V1/2 = 0.7 Vmax
The mitral valve area can be calculated as MV area (cm2) = 220/Pressure half time (msec)
Limitations of pressure half time
- Assumes normal left atrial and left ventricular compliance. This is not true immediately post valvuloplasty (72 hrs) and in left ventricular hypertrophy
- Aortic regurgitation leads to increased left ventricular diastolic pressure and thus shorter pressure half time. Hence Mitral valve area is over estimated.
- Angle needs constant intercept angle parallel to the flow
- Atrial fibrillation - several beats need to be averaged.
- Atrial septal defect - left to right shunt, shortened pressure half time and hence mitral valve area over estimated.
- Mitral regurgitation does not affect pressure half time.
Continuity equation Mitral valve area
Mitral valve area = transmitral stroke volume / velocity time integrale of the MS jet.
- M-Mode Echo
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- Continuous Wave Doppler Echo
- 3-D Echo of Rheumatic Mitral Stenosis 1
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- 3-D Echo of Rheumatic Mitral Stenosis 2
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- 3-D Echo of Rheumatic Mitral Stenosis 3
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- Calcific Mitral Stenosis Continuous Wave Doppler
- Calcific Mitral Stenosis Severe 1
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- Calcific Mitral Stenosis Severe 2
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- Calcific Mitral Stenosis Severe 3
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- Calcific Mitral Stenosis Severe 4
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- Calcific Mitral Stenosis Severe 5
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