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Gross pathology of heart showing mitral stenosis

Image: „Gross pathology of heart showing mitral stenosis” by CDC. Licence: Public Domain


Introduction

Mitral valve stenosis is usually a long-term sequela of rheumatic fever. The severity may depend on the patent area of the mitral orifice and determines which symptoms occur.

Phonocardiograms-from-normal-and-abnormal-heart-sounds

Image: Phonocardiograms from normal and abnormal heart sounds. By Madhero88, License: CC BY 3.0

Definition of Mitral Stenosis

Mitral valve stenosis refers to a narrowing of the mitral valve, which obstructs the filling of the left ventricle.

Etiology of Mitral Stenosis

The most common cause of mitral valve stenosis is rheumatic fever, which may date back many years. Therefore, asking the patient about the history of frequent bacterial tonsillitis is important. Rarely, there may be congenital stenosis in the mitral valve area.

Classification of Mitral Stenosis

Grades of Severity of Mitral Stenosis

Mitral valve stenosis

Image: Mitral valve stenosis. By Blausen Medical Communications, License: CC BY 3.0

Depending on the area of the mitral orifice, mean pressure gradient, and mean pulmonary capillary pressure, mitral valve stenosis can be divided into the severity grades of mild, moderate and severe. The mild grade has a pressure gradient of < 7 mm Hg, an orifice that is between 1.5 and 2 cm2, and a mean pulmonary capillary pressure of < 20 mm Hg.

The moderate grade is characterized by a mean pressure gradient of 8–15 mm Hg, an orifice of 1–1.5 cm2, and a mean pulmonary capillary pressure of 21–25 mm Hg. In severe mitral stenosis, the mean pressure gradient increases to > 15 mm Hg, the orifice drops below 1 cm2 and the mean pulmonary capillary pressure is > 25 mm Hg.

Pathophysiology of Mitral Stenosis

Because of the stenosis of the mitral valve, blood cannot flow properly into the left ventricle. This causes blood stasis in the left atrium, and blood flows back into the lungs to the pulmonary veins, and ultimately into the right heart. Therefore, there is a risk of right heart failure and an increased risk of atrial fibrillation due to the overstretching of the left atrium. Atrial fibrillation may increase the risk of embolization and may result in acute ischemia of the legs, stroke, or mesenteric ischemia

Symptoms and Clinical Presentation of Mitral Stenosis

The severity of the disease determines which symptoms occur. The expansion of the left atrium may lead to atrial fibrillation and thrombi, and therefore to arterial embolisms. Due to the congestion of blood in the lungs, this leads to pulmonary hypertension with symptoms such as dyspnea and nocturnal cough. Signs of right heart failure may also occur.

Reduced cardiac output leads to:

  • Performance degradation
  • Fatigue
  • Peripheral cyanosis

A late finding and a poor prognostic factor mean that the right ventricle can no longer keep up with the increased pressure transmitted backward from the left atrium.

A physical examination will reveal palpation in mitral valve stenosis. Other presentations include right ventricular heave if the patient has pulmonary hypertension, and the point of maximal impulse is normal or decreased.

Remember: Blood flows across the mitral valve and into the left ventricle during diastole.

A physical examination will also reveal mid-diastolic murmur. This murmur is heard loudest at the mitral area (apex) and has a ‘rumbling’ characteristic. It radiates toward the axilla and is heard as an opening ‘snap’ as the calcific valve is forced open by the left atrial contraction. Atrial fibrillation may be a consequence of the dilated left atrium.

Progression and Special Types of Mitral Stenosis

The progression of mitral valve stenosis depends on the severity. Pulmonary edema and right heart failure are the leading causes of death. Arterial and pulmonary embolisms are also complications that are potentially fatal.

Diagnosis of Mitral Stenosis

Auscultation of Mitral Stenosis

During auscultation, a loud first heart sound, as well as a split-second heart sound and a mitral opening snap, can be heard. A mid-diastolic rumbling murmur can be best heard over the cardiac apex. A sign of reactive pulmonary regurgitation is the Graham Steel murmur. A presystolic crescendo murmur can be heard.

mitral-stenosis

Image: Mitral stenosis. By Lecturio

Radiological Examination of Mitral Stenosis

An ECG may show a P with double peaks, as well as a right ventricular hypertrophy mark, and a right axis deviation. A radiograph may also show a right heart enlargement, as well as an enlarged left atrium, and a mitral configuration. During echocardiography, the valve can be readily assessed and quantification of the grade of stenosis can be made. In addition, cardiac catheterization can be performed for evaluation.

Treatment of Mitral Stenosis

Treatment Options for Mitral Stenosis

Conservative treatment options include drug treatment of heart failure and maintaining normal sinus rhythm, as well as thromboembolism and prophylaxis for endocarditis. The catheter method offers the possibility of a mitral valve valvuloplasty, which can help avoid a large surgical intervention.

Surgical repair or replacement of the mitral valve may be required if the patient stays symptomatic despite medical treatment. Mitral valve replacement is indicated with moderate stenosis or with a failure of valvuloplasty.

Atrial fibrillation occurring as a complication of mitral stenosis should be treated. Anticoagulation treatment and the restoration of normal sinus rhythm are goals. Treatment of fluid overload with diuretics is crucial.

Heart valve repair

Image: Mitral Valvuloplasty. By Blausen Medical Communications, License: CC BY 3.0

Complications of Mitral Stenosis

Complications of mitral stenosis include arterial embolism, bacterial endocarditis, and pulmonary edema.

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