Mitral stenosis echocardiography

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

Overview

Transthoracic echocardiography (TTE) may be helpful in the diagnosis of mitral stenosis. Findings on a transthoracic echocardiography (TTE) should be performed among patients with suspected mitral stenosis to confirm the diagnosis and to establish the baseline severity of disease. It should then be performed to monitor the course of disease over time. Echocardiography findings of mitral stenosis include 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. TEE should also be performed prior to percutaneous mitral balloon commissurotomy for the evaluation of the presence of left atrial thrombus.

Echocardiography

• Echocardiography is the standard and by using various techniques the transmitral flows can be converted to valve areas.
• The mitral valve area can be directly planimetered in some cases.
• Echocardiographic findings also predict the success/failure of balloon valvuloplasty.
• Coexisting valve dysfunction can be identified as well as pulmonary hypertension and right ventricular 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 maybe 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

Complete echocardiographic examination of mitral valve include M-mode tracing, multiple two dimensional views, and Doppler flow evaluation.

Echocardiographic Assessment of Mitral Stenosis Severity

Severity	Mild	Moderate	Severe
Mitral valve area	2.2 - 1.5	1- 1.5	<1
Pressure Half time (msec)	100 - 150	150 - 220	>220
Mean Pressure Gradient	<5	5-10	>10
TR velocity	<2.7	2.7-3	>3
Pulmonary artery pressure	<30	30-50	>50

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 or sometimes even flat. Though least reliable, 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 of less than 10 mm/sec (normal is >60 mm/sec) recoded during suspended respiration suggests severe mitral stenosis. 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. Opening snap usually coincides with E point.

The images below show decreased E-F slope:

Mitral Stenosis M Mode

Mitral Stenosis M Mode. Leaflet tips bright (calcified) and thickened and E/F slope decreased

2D-Echocardiography

• This is a reliable method of assessing the severity of stenosis.
• As with any stenotic valve, the main diagnostic feature in the parasternal long axis view is the doming of the entire valve into ventricle during diastole. This is due to the reduced mobility of the valve tips compared to the base of the leaflets leading to development of persistent left atrio-ventricular(AV) gradient. With this orientation, maximum opening area of mitral valve during diastole can be measured by direct planimetry of the two dimensional image. Valve orifice area of <1 cm2 is considered severe.
• During atrial contraction when the AV gradient increases, the valves open abruptly producing opening snap and a knee bend appearance on the precordial long axis view. 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.

Echocardiogram below shows knee bend with opening snap (Time 0:00-0:07), decreased E-F slope (Time 0:08-0:12), measurement of orifice area (Time 0:25-0:37) {{#ev:youtube|Jks98rwwsh8}}

Doppler Echocardiography

Mean Transmitral Valve Gradient

Can be measured by tracing the area-under-the-curve of the mitral E and A waves obtained by continuous Doppler. The severity of stenosis can be assessed as mild (<5), moderate (5-10) and severe (>10). Peak transmitral gradient can be calculated from velocity of mitral inflow using modified Bernoulli equation:

Peak transmitral gradient= 4 x (peak velocity)2

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 V_1/2 = 0.7 V_max

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.

Exercise Doppler Echocardiography

• 2008 ACC/AHA guidelines recommend that when there is a discrepancy between resting doppler echocardiographic findings, clinical findings, symptoms, and signs in a patient with MS, exercise doppler echocardiography should be performed.
• In those who cannot exercise, dobutamine can be used to increase the heart rate.

Continuity Equation Mitral Valve Area

Mitral Valve Area = (LVOT diameter)2 x 0.785 x TVILVOT
                    ----------------------------------
                                   TVIMV

LVOT: Left Ventricular Outflow Tract

TVILVOT: Time Velocity Integral of Left Ventricular Outflow Tract

TVIMV: Time Velocity Integral of Mitral Valve

Echocardiography Examples of Mitral Stenosis

• Continuous Wave Doppler Echo

Sewing Ring Ring dehiscence leading to Mitral Stenosis Continuous Wave Doppler

• 3-D Echo of Rheumatic Mitral Stenosis 1

{{#ev:youtube|-wLGHHFZIrM}}

• Calcific Mitral Stenosis Continuous Wave Doppler

• Calcific Mitral Stenosis Severe 1

{{#ev:youtube|9yPfTxBAq3s}}

2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

Recommendations for Diagnostic Testing: Initial Diagnosis of Rheumatic MS Referenced studies that support the recommendations are summarized in Online Data Supplement

Class I

1.   In patients with signs or symptoms of rheumatic MS, TTE is indicated to establish the diagnosis, quantify hemodynamic severity, assess concomitant valvular lesions, and demonstrate valve morphology (to determine suitability for mitral commissurotomy)(Level of Evidence: B-NR) 2.   In patients considered for percutaneous mitral balloon commissurotomy (PMBC), TEE should be performed to assess the presence or absence of LA thrombus and to evaluate the severity of MR(Level of Evidence: C-LD)

Recommendation for Diagnostic Testing: Exercise Testing in Patients With Rheumatic MS

Class I

1.   In patients with rheumatic MS and a discrepancy between resting echocardiographic findings and clinical symptoms, exercise testing with Doppler or invasive hemodynamic assessment is recommended to evaluate symptomatic response, exercise capacity, and the response of the mean mitral gradient and pulmonary artery pressure.(Level of Evidence: C-LD)

2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary

Class I

"1. Transthoracic echocardiography (TTE) is indicated in patients with signs or symptoms of mitral stenosis (MS) to establish the diagnosis, quantify hemodynamic severity (mean pressure gradient, mitral valve area, and pulmonary artery pressure), assess concomitant valvular lesions, and demonstrate valve morphology (to determine suitability for mitral commissurotomy). (Level of Evidence: B)"

"2. Transesophageal echocardiography (TEE) should be performed in patients considered for cutaneous mitral balloon commissurotomy to assess the presence or absence of left atrial thrombus and to further evaluate the severity of mitral regurgitation (MR). (Level of Evidence: B)"

"3. Exercise testing with doppler or invasive hemodynamic assessment is recommended to evaluate the response of the mean mitral gradient and pulmonary artery pressure in patients with MS when there is a discrepancy between resting doppler echocardiographic findings and clinical symptoms or signs. (Level of Evidence: C)"

2008 and Incorporated 2006 ACC/AHA Guidelines for the Management of Patients with Valvular Heart Disease (DO NOT EDIT)

Echocardiography Indications (DO NOT EDIT)

Class I

"1. Echocardiography should be performed in patients for the diagnosis of mitral stenosis, assessment of hemodynamic severity (mean gradient, mitral valve area, and pulmonary artery pressure), assessment of concomitant valvular lesions, and assessment of valve morphology to determine suitability for percutaneous mitral balloon valvotomy (PMBV). (Level of Evidence: B)"

"2. Echocardiography should be performed for reevaluation in patients with known mitral stenosis and changing symptoms or signs. (Level of Evidence: B)"

"3. Echocardiography should be performed for assessment of the hemodynamic response of the mean gradient and pulmonary artery pressure by exercise Doppler echocardiography in patients with mitral stenosis when there is a discrepancy between resting Doppler echocardiographic findings, clinical findings, symptoms, and signs. (Level of Evidence: C)"

"4. Transesophageal echocardiography in mitral stenosis should be performed to assess the presence or absence of left atrial thrombus and to further evaluate the severity of MR in patients considered for percutaneous mitral balloon valvotomy (PMBV). (Level of Evidence: C)"

"5. Transesophageal echocardiography in mitral stenosis should be performed to evaluate MV morphology and hemodynamics in patients when transthoracic echocardiography provides suboptimal data. (Level of Evidence: C)"

Class III

"1. Transesophageal echocardiography in the patient with mitral stenosis is not indicated for routine evaluation of MV morphology and hemodynamics when complete transthoracic echocardiographic data are satisfactory. (Level of Evidence: C)"

Class IIa

"1. Echocardiography is reasonable in the re-evaluation of asymptomatic patients with mitral stenosis and stable clinical findings to assess pulmonary artery pressure (for those with severe mitral stenosis, every year; moderate mitral stenosis, every 1 to 2 years; and mild MS, every 3 to 5 years). (Level of Evidence: C)"