Makindo Medical Notes

Related Subjects: | Mitral Regurgitation (Incompetence) | Mitral Stenosis | Mitral Stenosis vs Regurgitation | Mitral Valve Prolapse | Atrial Fibrillation (AF) | Cardiac Valve Replacement | Prosthetic Valves

About

• Mitral valve disease, often secondary to rheumatic fever, is treatable with surgery.

Aetiology

• The normal cross-sectional area of the mitral valve is 5 cm², but symptoms usually begin when the valve area is reduced to 1-2 cm².
• Rheumatic heart disease (RHD) causes scarring and contraction of the valve, leading to a classic "fish-mouth" appearance.
• Anticoagulation is recommended if atrial fibrillation (AF), paroxysmal AF (PAF), or a previous cardiac embolus is present.
• Progressive scarring and narrowing of the mitral valve can occur due to past episodes of rheumatic fever.

Causes

Clinical Features

• Pulse: Atrial fibrillation with low volume and systemic emboli.
• Pulmonary edema (not related to left ventricular failure).
• Mid-diastolic murmur with presystolic accentuation if in sinus rhythm.
• Loud S1 sound with a tapping apex beat due to wide-open valve cusps during systole.
• Right ventricular lift and loud P2 sound, indicating pulmonary hypertension.
• Ortner’s syndrome: Hoarseness caused by pressure on the left recurrent laryngeal nerve from an enlarged left atrium.
• Dysphagia due to an enlarged left atrium pressing on the esophagus.
• Left atrial enlargement may compress the left bronchus, leading to bronchiectasis.

A shortened interval between S2 and the opening snap indicates increased left atrial pressure, which is strongly associated with severe mitral stenosis

Decompensation

• Can occur with exercise, emotional stress, or during the second trimester of pregnancy.
• Infections or uncontrolled atrial fibrillation can worsen symptoms.

Differential Diagnosis

• A left atrial myxoma can mimic mitral stenosis. Myxomas can obstruct the mitral valve during diastole and cause similar symptoms, including a characteristic "tumour plop."

Investigations

• Blood Tests: Full blood count (FBC), Urea & Electrolytes (U&E), Liver Function Tests (LFTs), and C-reactive protein (CRP) to rule out infective causes.
• ECG: Findings may include atrial fibrillation, P mitrale, right bundle branch block (RBBB), and right ventricular hypertrophy.
• CXR: Enlarged left atrium, straight left heart border, pulmonary edema, and enlarged pulmonary artery or right ventricle.
• Echocardiogram: Poor leaflet separation during diastole, with calcification and fusion of valve leaflets. Transesophageal echocardiogram (TEE) is the most accurate for evaluating the mitral valve.
• Cardiac Catheterization: Used to measure pressure gradients between the left atrium (via PA wedge) and left ventricular end-diastolic pressure (LVEDP), which is usually >15 mmHg in severe cases.

Severity by Valve Area

• Normal: 4-6 cm²
• Mild: 1.5-2.5 cm²
• Moderate: 1-1.5 cm²
• Severe: < 1 cm²

Management