Laboratory Studies
Rheumatic heart disease
Laboratory studies are nonspecific, unless the patient is experiencing an acute attack of recurrent rheumatic fever, in which case, C-reactive protein, sedimentation rate, and antistreptolysin O (ASLO) antibodies are evident
Chronic rheumatic mitral valve disease
Persistence of elevated levels of antibody to the streptococcal group A carbohydrate occur in most patients with chronic rheumatic mitral valve disease.
Systemic lupus erythematosus
Obtain studies for evaluation of antinuclear antibodies, antibodies to double stranded DNA, and lupus erythematosus (LE) cells.
Amyloidosis
Assess for amyloid deposits in affected tissues.
Electrocardiography
Electrocardiographic (ECG) findings are often within reference ranges in patients with mild mitral stenosis (MS).
In those with moderate-to-severe MS, ECG reveals left atrial enlargement, right ventricular hypertrophy, and, often, right atrial enlargement. It also reveals atrial dysrhythmia. A fragmented QRS (RSR', R or S wave notching in two contiguous leads) has been described in patients who have severe MS, lower ejection fraction, and increased pulmonary artery pressure. [8]
Chest Radiography
Findings of patients with mitral stenosis (MS) on chest radiographs may include the following:
-
Left atrial enlargement
-
Pulmonic trunk and right ventricular and right atrial enlargement
-
Pulmonary venous congestion that results in redistribution of pulmonary blood flow with greater flow to the upper lobes and interstitial edema manifested by Kerley B lines
Echocardiography
Transthoracic and transesophageal echocardiography are the most important diagnostic tools for evaluating patients with mitral stenosis (MS). In patients with acquired valvular disease, echocardiographic assessment should include the morphologic and functional changes that indicate the type and mechanism of the defect and its stage/severity. [9]
Transesophageal echocardiography is recommended when transthoracic examination is incomplete, especially if left atrial thrombus is suspected. It is also used in the operating room and catheterization laboratory to assess the effectiveness of intervention.
Echocardiography provides the following:
-
Direct anatomic data is provided, including visualization of valve leaflet morphology and motility and measurement of valve orifice dimensions, as well as the degree of left atrial dilation.
-
Hemodynamic and physiologic data are provided, including the pressure gradient across the stenotic mitral valve, the presence and severity of mitral regurgitation, and the degree of pulmonary hypertension.
-
Spontaneous echo contrast is common in patients with MS, and its presence in the left atrium is associated with a higher risk of thromboembolism. One study postulated that platelet activation via increased sympathetic activity is responsible for this phenomenon. [10]
Histologic Findings
Cardiac involvement in rheumatic fever is characterized by inflammation of the endocardium and myocardium. Histologic changes are not observed during the early stage of myocarditis but become evident at later stages of the inflammatory process. The changes include tissue edema and a cellular infiltrate consisting of lymphocytes and plasma cells but few polymorphonuclear white blood cells.
Endocardial inflammation of the mitral valve produces essentially the same histologic changes observed in myocarditis.
Magnetic Resonance Imaging and Computed Tomography Scanning
MRI is infrequently used; however, experience with this imaging modality is much less than with echocardiography. [11]
Multislice CT scanning has been described as a new modality to assess the mitral valve area in patients with MS. [11, 12]
Cardiac Catheterization
Cardiac catheterization can be used to obtain direct measurement of the pressure gradient across the mitral valve as well as pulmonary artery pressure and pulmonary vascular resistance.
Note the following:
-
The mitral valve area can be calculated using the Gorlin formula.
-
Currently, the diagnosis and hemodynamic assessment of patients with MS are performed noninvasively with echocardiography.
-
Cardiac catheterization may be needed to supplement the information obtained noninvasively. More commonly, it is performed to accomplish percutaneous balloon valvuloplasty.
-
Possible complications of cardiac catheterization include tachyarrhythmias, bradyarrhythmias, and vascular occlusion. Balloon valvuloplasty may result in significant mitral regurgitation.
-
Postcatheterization complications include hemorrhage, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm.
-
Acquired Mitral Stenosis. Hemodynamic changes in severe mitral valve stenosis (MS). MS causes an obstruction (in diastole) to blood flow from the left atrium (LA) to the left ventricle (LV). Increased LA pressures are transmitted retrograde to pulmonary veins and pulmonary capillaries, resulting in capillary leak with subsequent development of pulmonary edema. To overcome pulmonary edema, the arterioles constrict, increasing pulmonary pressures. Over time, capillaries develop intimal thickening, causing fixed (permanent) pulmonary hypertension. The right ventricle (RV) hypertrophies to generate enough pressure to overcome the increased afterload. Eventually, the RV fails, which manifests as hepatomegaly and/or ascites, edema of the extremities, and cardiomegaly on radiography.
