Combined Mitral Valve Disease

Pathomorphology and hemodynamic disorders

According to statistics, isolated lesions of the valvular apparatus are relatively rare. For example, pure mitral stenosis is detected in only one-third of patients with rheumatic heart disease, while isolated regurgitation against the background of rheumatic fever is extremely rare. Most commonly, a combined valve defect develops.

The underlying pathomorphology involves dual damage to the valvular apparatus:

• Cusp fusion: leads to narrowing of the atrioventricular orifice (forming the stenosis component).
• Cusp deformation: prevents them from closing tightly during cardiac contraction (forming the regurgitation component).

This valve structure triggers a complex cascade of hemodynamic disorders. On the one hand, during the diastolic phase, a mechanical obstruction to normal blood outflow from the left atrium (LA) to the left ventricle (LV) arises. On the other hand, during systole, a portion of the blood is regurgitated back from the LV into the LA, resulting in pathological regurgitation.

The main difference between combined and isolated stenosis lies in the remodeling of the cardiac chambers. While pure stenosis predominantly affects the left atrium, the combined variant leads to hypertrophy of both the left atrium and the left ventricle. Enlargement (dilatation) and thickening of the LV walls occur due to significant volume overload caused by continuous blood regurgitation.

Physical examination findings

Physical examination of a patient with combined mitral valve disease reveals signs of both components of the lesion.

On palpation of the precordial region, the following symptoms are determined:

• Enhanced apical impulse — a consequence of left ventricular hypertrophy.
• Lateral displacement of the apical impulse — a reliable marker of left ventricular dilatation.
• «Cat's purr» phenomenon (palpable thrill of the chest wall). Depending on the severity of the components of the defect, this thrill can be detected in either the systolic or diastolic phase.

The auscultatory findings at the apex of the heart are also of a mixed nature:

1. A diastolic murmur is heard, indicating the presence of mitral stenosis (blood has difficulty passing through the narrowed orifice).
2. A prolonged, blowing systolic murmur is present, which is a classic sign of mitral regurgitation (turbulent blood flow returning into the atrium).

Criteria of predominance: stenosis or regurgitation?

To choose the management strategy, it is critically important for the physician to understand which component of the defect dominates. Differential diagnosis is based on the analysis of sound phenomena and radiographic findings.

Signs of mitral stenosis predominance:

• Auscultation: the first heart sound (S1) becomes loud, acquiring a specific «snapping» quality.
• Radiography: significant enlargement of the left atrium comes to the forefront. Barium swallow demonstrates its displacement along a small-radius arc.

Signs of mitral regurgitation predominance:

• Auscultation: the first heart sound sounds diminished (due to the absence of the closed-valve period and impaired contractility).
• Radiography: signs of marked left ventricular enlargement dominate. The left atrium is also enlarged; however, the contrasted esophagus in this case is displaced along a large-radius arc.

Instrumental verification of the diagnosis

Definite confirmation of the diagnosis and assessment of the severity of hemodynamic shifts require instrumental methods.

• Echocardiography (EchoCG): allows visualization of the valve and precise assessment of the degree of left ventricular dilatation and hypertrophy.
• Pulsed-wave Doppler: indispensable for directly detecting the systolic blood regurgitation flow and identifying specific velocity signs of mitral stenosis.
• Angiocardiography and cardiac catheterization: invasive methods used in complex cases. These are what allow for a definitive, most accurate judgment regarding the severity of the defect and the predominance of one component over the other prior to planning cardiac surgery.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Mechanisms of the «cat's purr» formation during different phases of the cardiac cycle.
• Radiographic anatomy of the heart and esophageal displacement along arcs of various radii.
• Echocardiographic criteria for assessing the degree of regurgitation using pulsed-wave Doppler mapping.
• Indications for angiocardiography and cardiac chamber catheterization.

Other topics in the "Cardiovascular system" section

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