Journal of the Saudi Heart Association (2011) 23, 51–58
King Saud University
Journal of the Saudi Heart Association www.ksu.edu.sa www.sha.org.sa www.sciencedirect.com
MINI REVIEW – CONTINUING MEDICAL EDUCATION
Echocardiography in mitral stenosis A.S. Omran, Ahmed A. Arifi *, A.A. Mohamed Department of Cardiac Sciences, King Abdulaziz Cardiac Center, National Guard Health Affairs, Saudi Arabia Received 18 July 2010; accepted 18 July 2010 Available online 7 September 2010
KEYWORDS Echocardiography; Mitral stenosis; 3D echocardiography
Abstract Echocardiography plays a major role in diagnosis, etiology and severity of Mitral Stenosis (MS), analysis of valve anatomy and decision-making for intervention. This technique has also a crucial role to assess consequences of MS and follow up of patients after medical or surgical intervention. In this article we review the role of conventional echocardiography in assessment of mitral stenosis and future direction of this modality using 3D echocardiography. ª 2010 King Saud University. Production and hosting by Elsevier B.V. All rights reserved.
1. Introduction In normal cardiac physiology, the mitral valve opens during left ventricular diastole, to allow blood to flow from the left atrium to the left ventricle. This flow direction will be maintained as long as the pressure in the left ventricle is lower than the pressure in the left atrium and the blood flows down the pressure gradient. Mitral stenosis (MS) is a mechanical obstruction in blood flow from the left atrium to the left ventricle. Obstruction happens due to thickening and immobility of the leaflets, thickening and fusion of the chorda tendinae or mitral annular and commissural calcification. The normal area of the mitral valve orifice is * Corresponding author. Address: King Abdulziz Cardiac Center, Mail Code 1413, P.O. Box 22490, Riyadh 11426, Saudi Arabia. E-mail address: arifi
[email protected] (A.A. Arifi). 1016-7315 ª 2010 King Saud University. Production and hosting by Elsevier B.V. All rights reserved. Peer review under responsibility of King Saud University. doi:10.1016/j.jsha.2010.07.007
about 4–6 cm2 when the mitral valve area goes below 2 cm2, the valve causes an impediment to the flow of blood into the left ventricle, creating a pressure gradient across the mitral valve. This gradient may increase by the rise in heart rate or cardiac output. When the mitral valve area becomes less than 1 cm2, there will be an increase in the left atrial pressure to overcome the valve gradient. This rise in the left atrial pressure is then transmitted to the pulmonary vasculature and causes pulmonary hypertension and eventually pulmonary congestion and edema. Mitral stenosis consists of 12% of all valvular heart disease in Euro Heart Survey. Etiology of MS in adult patients in the great majority of cases (more than 90%) is the rheumatic involvement of the mitral valve. Other etiologies such as infective endocarditis, mitral annular calcification in elderly patients, congenital malformation (parachute mitral valve), systemic lupus erythematosis, carcinoid heart disease, endomyocardial fibrosis and rheumatoid arteritis are representing less than 10% of adult cases. 2. Diagnosis of MS2.1. Transthoracic 2D – echocardiography
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Mitral valve assessment with echocardiography should include the pattern of valve involvement and calcification, severity of
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stenosis, associated mitral regurgitation and other co-existent valve lesions and atrial chamber dilatation and function. Mitral stenosis can be assessed in parasternal, apical or subcostal views. As with any stenotic valve the main diagnostic feature in the parasternal long axis view (Fig. 1) as in rheumatic MS, the anterior mitral leaflet (AMVL) shows diastolic doming or hockey-stick shape. And the posterior mitral leaflet (PMVL) has restricted motion or is totally immobile. This doming is due to the reduced mobility of the valve tips compared to the base of the leaflets. Echocardiography can also adequately assess the Subvalvular apparatus changes such as thickening, shortening, fusion of chordal and calcification (Fig. 1). Color Doppler in this view with diastolic turbulence across the mitral valve confirms the diagnosis. On the other hand, Parasternal short axis view of the mitral valve is used to assess the leaflets thickening and
fusion of commissures. The parasternal short axis view is also used to assess the mitral valve orifice area by planimetry of the mitral leaflets at the level of tips (Fig. 2). 3. Indices of stenosis severity The Following are different means of measurements by echocardiography to assess the severity of MS, which are mandatory in all patients: Planimetry of mitral valve at the level of the leaflets tips in parasternal short axis view (Fig. 2). This method is a very familiar technique by 2D echocardiography but the same method can also be used in 3D echocardiography en-face view of mitral valve (Fig. 9). However, newly developed QLAB software in 3D echo is now available for calculation of mitral valve orifice area which requires further validation (Fig. 10).
AMVL
LV LA PMVL
Figure 1 Parasternal long axis view in diastole, showing diastolic doming (hockey-stick shape) of anterior mitral valve leaflet (AMVL) and thickened, restricted posterior mitral valve leaflet (PMVL). RV = right ventricle, LV = left ventricle, LA = left atrium.
Figure 2 Parasternal short axis view of the mitral valve at the level of the tips to measure mitral valve area (MVA) by planimetry. (A) Prior to percutaneous balloon mitral valvuloplasty (PBMV), showing fused both commissures with MVA = 1.2 cm2. (B) Same patient after PBMV, showing complete opening of the anterolateral commissure and partial opening of the posteromedial commissure. MVA = 2.0 cm2.
Echocardiography in mitral stenosis Calculation of mitral valve area (MVA) by pressure half-time (P1/2 t) should be done in an apical four chamber view using continuous wave Doppler (Fig. 3). Pressure half-time method is not valid immediately after percutaneous balloon mitral
Figure 3
53 valvuloplasty (PBMV). MVA should be averaged in 3 consecutive beats and in case of atrial fibrillation in it should 5 beats. Mean pressure gradient across the mitral valve can be measured in apical views. Modal Doppler (most dense portion of
Calculation of the mitral valve area (MVA) by the method of pressure half-time (P1/2 t).
Figure 4 Continuous wave Doppler parallel to the mitral inflow in apical 4 chamber view to measure mean peak gradient (Mean PG) across the mitral valve. Measurements should be done in 3–5 consecutive beats and averaged.
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Figure 5 (A) Estimation of pulmonary artery systolic pressure (right ventricular systolic pressure) using TR velocity and gradient in short axis view in a patient with severe MS and severe pulmonary hypertension (B) Calculation of left atrial volume using method of discs (MOD) in apical 4 chamber view in same patient, showing severe increase of LA volume.
Table 1
EAE/ASE recommendations for classification of mitral stenosis severity. Mild
Moderate
Severe
valve area (cm2)
>1.5
1.0–1.5
8–10 mm)
the Doppler curve) should be used for calculation (Fig. 4). The gradient can be measured by tracing the dense outline of mitral diastolic inflow and the mean pressure gradient is automatically calculated. The severity can be assessed as mild (10).
Thickening of chordal structures extending to one-third of the chordal length
Extensive thickening and shortening of all chordal structures extending down to the papillary muscles
Estimation of pulmonary artery systolic pressure and the right ventricular systolic pressure (RVSP) is necessary. It can be measured from tricuspid regurgitation velocity by Bernoulli equation (Fig. 5). RVSP can also be assessed during exercise in borderline cases.
Echocardiography in mitral stenosis
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Table 3 Assessment of mitral valve anatomy according to the Cormier score. Echocardiographic group
Mitral valve anatomy
Group 1
Pliable non-calcified anterior mitral leaflet and mild subvalvular disease (i.e. thin chordae >10 mm long) Pliable non-calcified anterior mitral leaflet and severe subvalvular disease (i.e. thickened chordae
