Laboratory Studies
No specific laboratory studies are necessary for patients with mitral stenosis in the absence of an abnormal bleeding history, although most proceduralists order routine screening laboratory tests, including platelet count and prothrombin time, prior to any catheter-based intervention.
Imaging Studies
A transthoracic echocardiogram (TTE) scoring system is widely used to assess the suitability of valve morphology for percutaneous mitral balloon valvuloplasty (PMBV). The system evaluates four components of the valve, each receiving 1-4 points: leaflet mobility, leaflet thickening, valvular calcification, and subvalvular apparatus deformity. [4] A score less than 8 predicts excellent long-term results. Scores from 9-12 deliver intermediate results whereas scores greater than 12 predict poorer long-term outcomes.
A three-dimensional TTE scoring system has demonstrated feasibility and reproducibility for assessing mitral valve morphology for suitability for PMBV. [5]
Symmetric fusion of the mitral leaflets is associated with better outcomes than asymmetric fusion. A commissural calcium score has also been used to complement the standard scoring system for patient selection; those with a higher degree of calcium are less likely to have successful outcomes. [6, 7]
Intracardiac echocardiography (ICE), a more invasive mode of cardiac imaging involving an ultrasound catheter in the right atrium, has also been used to evaluate mitral valve stenosis. ICE detects more extensive subvalvular disease than TTE or transesophageal echocardiography (TEE) and may improve patient selection for PMBV. Preprocedural ICE evaluation can be performed in the catheterization laboratory immediately prior to PMBV if it will be used to guide valvuloplasty during the procedure.
Interatrial septum thickness measurement on TEE does not appear to change in the presence of moderate to severe rheumatic mitral stenosis relative to those reported as normal values in cadaveric heart specimens. [8]
Other Tests
Coronary arteriography should be performed in selected patients prior to percutaneous mitral balloon valvuloplasty (PMBV). American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend coronary arteriography in men older than 35 years as well as women older than 35 years with coronary risk factors or who are postmenopausal. Patients with chest pain, evidence of ischemia, decreased left ventricular (LV) function, or a history of coronary artery disease should also undergo preprocedural coronary arteriography.
Transesophageal echocardiography (TEE) should be performed in all patients prior to PMBV to exclude left atrial thrombus.
Diagnostic Procedures
Transthoracic echocardiography (TTE), which allows two-dimensional evaluation of valve morphology and Doppler evaluation of transmitral gradients, is the principle method of diagnosis. Exercise echocardiography can be helpful in patients with ambiguous symptoms. Cardiac catheterization with measurement of left and right heart pressures and either pulmonary capillary wedge pressure or direct left atrial pressure (by transseptal puncture) was at one time the criterion standard for diagnosis prior to modern Doppler echocardiography. Although not necessary for diagnosis, cardiac catheterization is still sometimes helpful when echocardiographic data do not correlate well with symptoms.
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Mitral Valvuloplasty. The Inoue balloon catheter, seen here across the mitral valve, inflates in three stages. First, the distal portion of the balloon is inflated. The proximal portion of the balloon is then inflated, securing the position of the balloon across the mitral valve. Lastly, the middle portion of the balloon is inflated and partially splits the fused mitral valve leaflets. Note the catheter placed across the aortic valve into the left ventricle in addition to the transseptal balloon catheter.
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Mitral Valvuloplasty. These images are simultaneous tracings of pulmonary capillary wedge pressure and left ventricular pressure in a patient with mitral stenosis before valvuloplasty. The shaded area represents the gradient between the left atrium and the left ventricle. The mean gradient is 22 mmHg and the mitral valve area is 0.9 cm<sup>2</sup>.
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Mitral Valvuloplasty. Pulmonary capillary wedge pressure and left ventricular pressure in the same patient as in the previous image immediately after valvuloplasty. The mean gradient had decreased to 7 mmHg and the mitral valve area increased to 1.25 cm<sup>2</sup>.
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Mitral Valvuloplasty. Transthoracic echocardiogram (TTE) demonstrating severe mitral regurgitation with heavily calcified mitral valve and prolapse of the posterior leaflet into the left atrium.
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Mitral Valvuloplasty. Transesophageal echocardiogram (TTE) demonstrating prolapse of both mitral valve leaflets during systole.
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Mitral Valvuloplasty. Transthoracic echocardiogram (TTE) demonstrating bioprosthetic mitral valve dehiscence with paravalvular regurgitation.
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Mitral Valvuloplasty. Apical four-chamber echocardiographic view demonstrating restricted opening of the anterior and posterior mitral valve leaflet with diastolic doming of the anterior leaflet with left atrial enlargement.
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Mitral Valvuloplasty. Apical four-chamber view with color Doppler imaging demonstrating aliasing in the atrial side of the mitral valve consistent with increased gradient across the valve. This figure also shows mitral regurgitation and left atrial enlargement.
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Mitral Valvuloplasty. Magnified view of the mitral valve in the apical four-chamber view revealing restricted opening of both leaflets.
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Mitral Valvuloplasty. Transesophageal echocardiogram (TEE) in an apical three-chamber view showing calcification and doming of the anterior mitral leaflet and restricted opening of both leaflets.
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Mitral Valvuloplasty. Transesophageal echocardiogram (TEE) in an apical three-chamber view with color Doppler interrogation of the mitral valve revealing aliasing, which is consistent with an increased gradient across the mitral valve secondary to stenosis. Also shown in this image, a posteriorly directed jet of severe mitral regurgitation.
Tables
MVA |
Severity |
Hemodynamic Effects |
4-6 cm2 |
Normal |
Normal left atrial (LA) pressure and cardiac output |
2-2.5 cm2 |
Mild |
LA pressure elevated only with increased blood flow or heart rate |
1.5-2.0 cm2 |
Moderate |
LA pressure mildly elevated at rest with significant increase during exercise |
< 1.5 cm2 |
Severe |
Reduced cardiac output and dyspnea at rest |
Class I |
NYHA class II-IV with MVA < 1.5 cm2, favorable valve morphology, absence of LA thrombus, absence of mod-severe |
|
Asymptomatic with MVA < 1.5 cm2 and PAP >50 mmHg at rest or >60 mmHg with exercise |
Class IIa |
NYHA Class III-IV, MVA < 1.5 cm2 calcified valve, high surgical risk |
Class IIb |
Asymptomatic with MVA < 1.5 cm2 new atrial fibrillation |
|
NYHA class II-IV MVA >1.5 cm2 and PAP >50 mmHg at rest or >60 mmHg with exercise |
|
NYHA class III-IV, MVA < 1.5 cm2 calcified valve, low surgical risk |
AHA/ACC = American Heart Association/American College of Cardiology; LA = left atrium; MVA = mitral valve area; NYHA = New York Heart Association; PAP = pulmonary artery pressure. |
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