Mechanism of Development and Consequences
Hemodynamic disturbances in Prolapsus valvae mitralis are based on alterations in the normal function of the valvular apparatus. During left ventricular systole, when blood should be directed into the aorta, the mitral valve leaflets bulge backward toward the left atrium.
The primary hemodynamic consequence of such prolapse is the development of mitral regurgitation. Due to incomplete leaflet closure, regurgitation occurs—a pathological backflow of a portion of the blood into the atrium. It is important to emphasize that regurgitation is not an obligatory component of prolapse. Its presence and severity can vary significantly among patients: from a complete absence of backflow to clinically significant volumes.
Etiology: Why Does Prolapse Occur?
The vast array of causes leading to mitral valve prolapse is typically divided into two main categories depending on the primary lesion substrate.
- Connective tissue pathology. This group includes various connective tissue dysplasias, a striking example of which is Marfan syndrome. The main pathogenetic mechanism here is myxomatous transformation (or degeneration) of the tissue structures of the valve leaflets themselves, causing them to lose their normal density and elasticity.
- Heart diseases. Prolapse can be caused by congenital malformations, structural anomalies of the coronary arteries, and various myocardial diseases. The mechanism of pathology development in this case is different: valvular-ventricular disproportion occurs. This means there is a spatial mismatch between the sizes of the valve apparatus structures and the left ventricle itself.
Clinical Manifestations and Auscultation
The primary method for clinical (physical) detection of prolapse symptoms is auscultation. The overall sound pattern largely corresponds to the signs of mitral regurgitation and is characterized by the presence of a systolic murmur.
Typical auscultatory phenomena:
- Additional sound (systolic click). Distinctly auscultated at the cardiac apex precisely in mid-systole.
- Late systolic murmur. Occurs immediately after the click and has a crescendo character. This murmur is best localized at the left sternal border in its lower third.
Diagnostic features: The acoustic symptomatology of prolapse is extremely labile. Murmurs and sounds are much better detected with targeted changes in the patient's body position. For example, if the patient is asked to squat or strain, intracardiac hemodynamics change, which significantly enhances the auscultatory manifestations.
Complications and Instrumental Diagnostics
Although mitral valve prolapse may remain asymptomatic for a long time, it can provoke serious disturbances in the cardiac conduction system.
Among possible complications (rhythm and conduction disorders) are:
- Extrasystole;
- Paroxysmal tachycardia;
- Various blocks (disorders of electrical impulse conduction).
For final diagnosis verification and severity assessment, instrumental methods are used:
- EchoCG (echocardiography): allows real-time visualization of the unusual systolic motion—that very leaflet prolapse.
- Dopplerography: critically important for accurate qualitative and quantitative assessment of the degree of blood regurgitation.
Briefly: answers to topical questions
What are the specific ECG signs of mitral valve prolapse?
The provided sources do not list specific ECG signs of mitral valve prolapse. It is noted that MVP may be accompanied by ECG changes that can mimic ischemic heart disease. Possible complications of MVP include rhythm and conduction disorders: extrasystole, paroxysmal tachycardia, and heart blocks.
How is mitral regurgitation classified by degree of regurgitation in prolapse?
In mitral valve prolapse, the degree of regurgitation is assessed by Dopplerography. For mitral regurgitation on 2D Doppler echocardiography, a semi-quantitative assessment of severity is performed based on the depth of penetration and jet area in the left atrium with gradations: mild, moderate, severe. With severe regurgitation on color Doppler, a pronounced mosaic effect is observed, completely occupying the left atrium cavity. The most accurate quantitative assessment of the degree of blood backflow is performed during angiocardiography.
To memorize the auscultatory pattern: "A click in the middle, a growing stream at the end." The mid-systolic click heralds the late systolic regurgitation murmur.
Class and exam questions
Is Prolapse Always Accompanied by Blood Backflow?
No, regurgitation is not an obligatory component of mitral valve prolapse. It may be entirely absent, and its degree varies greatly among patients.
Why Are Patients Asked to Squat During Auscultation?
The auscultatory pattern in prolapse is highly labile. Changing body position or straining alters hemodynamics, making it possible to amplify murmurs and better hear the systolic click.
Which Genetic Syndrome is Frequently Associated with Prolapse?
A frequent cause is connective tissue pathology, for example, in Marfan syndrome, when myxomatous degeneration of the leaflets occurs.
What else to study on this topic
- Pathogenesis of Myxomatous Connective Tissue Degeneration
- Hemodynamic Foundations of Valvular-Ventricular Disproportion
- Echocardiographic Criteria for Mitral Valve Prolapse
- Mechanisms of Rhythm Disturbance Formation in MVP
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