Mitral stenosis: diagnosis and treatment

Auscultatory pattern of the defect

Mitral stenosis creates a unique sound pattern, primarily at the apex of the heart. The main pathognomonic sign is «quail rhythm» — a specific triple-component melody. It consists of a loud (snapping) first heart sound (S1), followed by the second heart sound (S2), and an additional opening snap of the mitral valve.

The extra click occurs in early diastole immediately after S2. Its mechanism lies in the abrupt tension of fused valve leaflets that fail to open fully. An important diagnostic criterion: the shorter the interval between S2 and the opening snap, the more severe the degree of stenosis.

In addition to heart sounds, a diastolic murmur is auscultated at the apex. It results from turbulent blood flow passing under pressure from the left atrium into the left ventricle through the narrowed orifice. The murmur is most pronounced at the moments of highest blood flow velocity — at the very beginning of diastole and at its end (presystolic accentuation due to atrial contraction). In severe cases, the murmur may fill the entire diastole. If a systolic murmur is simultaneously auscultated at the apex, it directly indicates concomitant mitral regurgitation.

Additional auscultatory signs are associated with the development of pulmonary hypertension:

• An accentuation of S2 and its splitting appear over the pulmonary valve area (due to high pressure in the pulmonary circulation, closure of the aortic and pulmonary valves occurs at different times).
• The Graham Steell murmur may also be detected at the same location — a diastolic murmur caused by relative pulmonary valve insufficiency against the background of its dilation.
• Along the left sternal border (in the area of absolute cardiac dullness), a systolic murmur is sometimes detected, indicating relative tricuspid regurgitation.

Instrumental diagnostic methods

To confirm the diagnosis and assess hemodynamics, a triad of basic investigations is used: electrocardiography, chest radiography, and echocardiography.

On the ECG during sinus rhythm, signs of left atrial overload and hypertrophy are recorded. P-mitrale forms — a broadened and notched P wave in leads I and II. With the progression of the defect, atrial fibrillation frequently develops, in which the P wave completely disappears. Pulmonary hypertension manifests on the ECG with signs of right ventricular hypertrophy: the electrical axis of the heart deviates to the right (right axis deviation), a tall R wave is recorded in leads V1–V2, and the ST segment and T wave are altered.

Chest X-ray reveals the formation of a typical «mitral configuration» of the heart. The cardiac «waist» is smoothed out due to the bulging of the third arch (left atrial appendage) and the second arch (pulmonary artery trunk). The pulmonary pattern changes: vascularity in the upper lobes increases, and signs of fluid transudation into the interstitial tissue appear. The dimensions of the left ventricle remain within normal limits, while the right ventricle and pulmonary trunk enlarge. Occasionally, calcification of the mitral valve itself can be seen on the image.

Echocardiography (EchoCG) is the gold standard for diagnosis. In M-mode, a specific marker is detected: both valve leaflets move concordantly (forward, parallel to each other), and their motion curve acquires a characteristic hooked or D-shape. Two-dimensional EchoCG provides the ability to visualize left atrial enlargement and right ventricular hypertrophy, detect mural intracavitary thrombi, and most importantly, accurately measure the area of the narrowed orifice.

Severity assessment and treatment approaches

Quantitatively, the degree of narrowing is assessed using Doppler echocardiography. This method calculates three key parameters: mitral valve area, transmitral pressure gradient (pressure drop between the left atrium and ventricle), and systolic pulmonary artery pressure. In complex cases, invasive methods — cardiac catheterization and angiocardiography — are used.

Treatment of mitral stenosis is divided into symptomatic and radical.

Conservative (medical) therapy aims to manage complications. If the patient develops heart failure against the background of atrial fibrillation, cardiac glycosides (e.g., digoxin) combined with diuretics are prescribed. To prevent thromboembolic complications, oral anticoagulants are invariably used.

The only method capable of eliminating the defect itself is surgical intervention. Depending on the clinical situation, the following are used:

1. Commissurotomy — mechanical incision of adhesions between valve leaflets.
2. Balloon valvotomy — minimally invasive dilation of the stenotic orifice by inflating a specialized balloon.
3. Valve replacement — complete replacement of the affected valve with a prosthetic valve.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Pathogenesis of pulmonary hypertension development in mitral stenosis
• Mechanism of P-mitrale formation on the electrocardiogram
• Calculation of the transmitral pressure gradient using Doppler echocardiography
• Differences between commissurotomy and balloon valvotomy: indications and contraindications
• Mechanism of Graham Steell murmur formation

Other topics in the "Cardiovascular system" section

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