Imaging modalities in mitral stenosis
Modern diagnostic imaging methods are used to assess the degree of valvular orifice narrowing and the severity of hemodynamic disorders:
- Cine-MRI. Used for precise measurement of the mitral valve area (MVA) using planimetry. During diastole, the smallest orifice is outlined. To achieve results comparable to echocardiography, a series of parallel thin slices is required. Images of mild valve disease show a signal loss area (flow void) directed from the left atrium to the left ventricle, as well as atrial dilatation.
- Phase-contrast MRI (Velocity-encoded CMR). Used for quantitative assessment of the orifice area. It is based on the analysis of transmitral flow velocity (pressure half-time method, PHT). However, in the presence of atrial fibrillation, which often accompanies severe stenosis, the accuracy of the method decreases.
- Multidetector computed tomography (MDCT). An alternative tool for planimetric evaluation of MVA. CT is excellent for detecting leaflet calcification, which is a sign of sclerosis and stenosis.
- Angiocardiography. Currently rarely used. The method is indicated when echocardiography cannot reliably assess the contribution of combined valve lesions or when diagnosis of concomitant coronary artery disease is required.
Causes of mitral stenosis
Rheumatic heart disease is the classic and most frequent cause.
- In the acute phase, pancarditis may develop, accompanied by mitral regurgitation (usually reversible).
- In the chronic stage, commissural fusion occurs, the tendinous cords (chordae tendineae) thicken and shorten, and the papillary muscles undergo fibrosis. A combination of stenosis and regurgitation is frequently observed. At the same time, pronounced stenosis physically limits the volume of blood regurgitation, so both valve defects are rarely severe at the same time (leaflet destruction leads to the predominance of regurgitation).
Non-rheumatic causes are less common and present a less specific pattern (e.g., simply thickened leaflets).
- Post-radiation injury: characterized by premature calcification of the valvular apparatus, combined with pulmonary fibrosis and vertebral anomalies.
- Senile calcific stenosis: develops against the background of prominent leaflet calcification, which is clearly visualized on CT.
Differential diagnosis
When mitral stenosis is clinically suspected, it is important to exclude non-valvular pathology that disrupts blood flow. Symptoms of stenosis can mimic left atrial masses:
- Ball-valve thrombus (ball-valve thrombus), periodically obstructing the orifice.
- Left atrial myxoma.
Briefly: answers to topical questions
What specific echocardiographic features are detected in rheumatic mitral stenosis?
Specific echocardiographic features of mitral stenosis include changes in leaflet motion and morphology.
- M-mode echocardiography — significant reduction in the diastolic closing rate of the anterior leaflet (flattening of the EF slope), unidirectional motion of the anterior and posterior leaflets, and a dome-shaped (or hockey-stick) diastolic motion of the anterior leaflet instead of the normal M-shaped pattern.
- Two-dimensional echocardiography — leaflet thickening, restricted leaflet motion, "doming" (in the parasternal long-axis view), as well as a narrowed orifice and increased echogenicity (in the short-axis view).
- Doppler echocardiography — increased transmitral diastolic pressure gradient (normal is 3–4 mmHg).
What changes in the cardiac silhouette are determined on a standard chest radiograph in mitral stenosis?
A standard chest radiograph in mitral stenosis demonstrates the formation of a specific mitral configuration of the cardiac silhouette.
- Alteration of the left heart border — elongation and bulging of the second and third arches occur.
- Flattening of the cardiac "waist" — the visual effect of the disappearance of the angle between the arches.
- Chamber enlargement — left atrial and right ventricular dilatation are detected.
- Vascular changes — radiological signs of pulmonary hypertension are determined, including pulmonary trunk enlargement.
What formula is used to calculate the mitral valve area by the pressure half-time (PHT) method?
The mitral valve area using the pressure half-time method is calculated by a specific mathematical formula.
- Calculation formula — Mitral valve area (cm²) = 220 / PHT.
- Parameter definition — PHT (pressure half-time) denotes the pressure half-time, measured in milliseconds.
To obtain the PHT value using continuous-wave Doppler, a line must be drawn along the slope of the transmitral flow spectral trace from the maximum velocity point, after which the ultrasound system automatically calculates the required time.
What hemodynamic complications of mitral stenosis can be detected by diagnostic imaging methods?
Diagnostic imaging methods in mitral stenosis can reveal the hemodynamic consequences of chronic pressure elevation:
- Pulmonary venous hypertension — blood volume redistribution, interstitial and alveolar pulmonary edema may occur.
- Cardiac chamber dilatation — left atrial enlargement due to chronic pressure elevation and right ventricular enlargement due to prolonged pulmonary hypertension.
- Tricuspid regurgitation — may develop with prolonged pulmonary hypertension and right ventricular dilatation.
Class and exam questions
Why are mitral stenosis and regurgitation in rheumatic disease rarely severe simultaneously?
The narrowing (stenosis) of the orifice itself acts as a barrier limiting the volume of blood that can flow backward (regurgitation).
How does CT assist in the diagnosis of senile mitral stenosis?
Computed tomography allows reliable and clear visualization of valve leaflet calcification, which is the primary cause of age-related (senile) stenosis.
What else to study on this topic
- Tricuspid valve pathology: stenosis and regurgitation
- Causes of secondary tricuspid regurgitation
- Radiological signs of right atrial enlargement
- Ebstein anomaly (Ebstein anomaly
- Echocardiographic assessment of regurgitation (color and pulsed-wave Doppler)
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