Myxomatous mitral valve

Myxomatous Mitral Valve Disease (MMVD) is a pathological condition affecting the mitral valve, one of the four valves in the heart, which regulates blood flow from the left atrium to the left ventricle. This disease is characterized by a process known as myxomatous degeneration, where the mitral valve leaflets become excessively floppy due to an accumulation of abnormal connective tissue. As a result, the valve may not close properly, a condition known as mitral valve prolapse (MVP), which can lead to mitral regurgitation, where blood leaks backward into the left atrium.

Etiology

The exact cause of myxomatous mitral valve disease is not fully understood, but it is believed to involve a combination of genetic and environmental factors. In some cases, MMVD is linked to hereditary connective tissue disorders such as Marfan syndrome and Ehlers-Danlos syndrome. However, in many instances, the disease occurs in individuals without a clear genetic predisposition.

Pathophysiology

In MMVD, the structural integrity of the mitral valve is compromised due to changes in the extracellular matrix, leading to the accumulation of a mucoid material within the valve leaflets. This process causes the leaflets to thicken and become floppy, preventing the valve from closing properly during ventricular contraction. The resultant mitral regurgitation can lead to volume overload in the left atrium and ventricle, eventually causing heart failure if left untreated.

Symptoms

Many individuals with myxomatous mitral valve disease may remain asymptomatic for years. However, symptoms can develop as the condition progresses, including:

• Shortness of breath, especially during exertion or when lying down
• Fatigue
• Palpitations
• Cough, particularly when lying down
• Swelling of the legs or feet due to fluid retention

Diagnosis

Diagnosis of MMVD involves a thorough medical history, physical examination, and specific diagnostic tests. A characteristic mid-systolic click followed by a late systolic murmur, heard through a stethoscope, may suggest mitral valve prolapse. Confirmatory tests include:

• Echocardiography: The primary diagnostic tool for assessing valve structure and function.
• Cardiac MRI: Provides detailed images of the heart's structure and can assess the severity of regurgitation.

Treatment

Treatment for myxomatous mitral valve disease depends on the severity of the condition and the presence of symptoms. Management strategies include:

• Regular monitoring for individuals without significant symptoms or mitral regurgitation.
• Medications such as beta-blockers or diuretics to manage symptoms.
• Surgical repair or replacement of the mitral valve for severe mitral regurgitation or symptomatic patients.

Prognosis

The prognosis for individuals with myxomatous mitral valve disease varies. Those with mild disease may lead a normal life with minimal intervention. However, severe mitral regurgitation can lead to complications such as atrial fibrillation, pulmonary hypertension, and heart failure, which require more aggressive treatment.

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