MITRAL STENOSIS
Definition
Mitral Stenosis is the narrowing of the Mitral valve opening and results in the reduced blood flow through the Mitral valve and backpressure into the chamber behind the valve.
Causes
1. Rheumatic heart disease
2. Lutembacher’s syndrome (Acquired mitral stenosis + Atrial septal defect)
4. Endomyocardial fibrosis
5. Hurters syndrome (Cardiomyopathy, mental retardation).
PATHOLOGY
The obstruction to the left ventricular inflow resulting in a rise in pressure in the left atrium and pulmonary circulation. The pulmonary blood flow need a pressure gradient of 10 mm Hg between pulmonary arteries and veins. To maintain the pressure gradient the pressure will be above 20 mm Hg and vaso constriction occurs. This affects the muscular arteries of the lower lobe, which shows medial hypertrophy. The area of the Mitral valve is 5 cm square.
In stenosis it is reduced to 1 cm Square. The pressure in the left atrium is about 6-12 mm of Hg. In stenosis to maintain adequate Cardiac output, the left atrial pressure increases to 30 mm or higher and the left atrial dilatation occurs results in pulmonary oedema, pulmonary hypertension, Right ventricular hypertrophy and failure and tricuspid regurgitation occurs.
Types of Mitral Stenosis
1. Leaf let type: The valves are stiff, rigid and calcified.
2. Commisural type: The valves look like fusion of commisures.
3. Chordae type: The valves look like chordae and are thick.
Symptoms
■ Shortness of breath, especially with exertion or when you lie down
■ Swollen feet or legs
■ Chest discomfort or chest pain
■ Dizziness or fainting
■ Coughing up blood
■ Fatigue, especially during increased physical activity
■ Heart palpitations — sensations of a rapid, fluttering heartbeat
■ Shortness of breath, especially with exertion or when you lie down
Clinical Features
1. Pulmonary hypertension: Dyspnoea, cough with frothy sputum, haemoptysis.
2. Right heart failure: Weakness, fatigue, oedema of feet.
3. Atrial fibrillation: Embolism, blindness, hemiparesis.
4. Vulvular lesions: Mitral regurgitation, aortic regurgitation and aortic stenosis
Complications
■ Pulmonary oedema
■ Right ventricular hypertrophy and failure
■ Tricuspid incompetence
■ Atrial fibrillation
■ Infections like subacute bacterial endocarditis, bronchopulmonary infections
■ Embolism: Cerebral (Hemiplegia, aphasia), pulmonary and renal hypertension
■ Enlarged left atrium.
INVESTIGATIONS
X-ray Chest
1. Enlarged left atrium
2. Enlarged right ventricle
3. Enlarged pulmonary conus
4. Lung changes like pulmonary congestion, pulmonary oedema, pulmonary infarction, pulmonary venous hypertrophy.
5. Calcification of the Mitral valve.
ECG
1. Early stage will be normal
2. Later stage: P wave will be absent.
Echocardiogram
This is one of the most valuable investigations to diagnose and assess the severity of muscles.
Diagnosis
1. Loud first heart sound is heard
2. Murmur heart in the mitral area
3. Backward displacement of the left ventricle by the enlarged right ventricle.
4. Diastolic heart murmur.
Treatment
The treatment will be either of medical and surgical.
Medical Treatment
In the mild cases or in the cases where surgery is contraindicated, treatment is by
1. Bedrest
2. Salt free diet
3. Diuretics like furosemide
4. Anticoagulants for embolism.
Surgical Treatment
Valvotomy
a. A closed valvotomy: The procedure is an instrument is inserted through a ventricle, passed up through the mitral valve and dilated with in it.
b. An open valvotomy: The procedure is the heart is opened and the cusps of the valve mobilized under direct vision.
Balloon Vuloplasty
Transcutaneous balloon dilatation of stenosed valves is being done with good success in cases of noncalcified, mobile mitral valve, Pregnancy, when cardiac surgery is contraindicated in the older patients with severe valvular deformity.
Advantages
1. Avoids major surgery
2. The restenosed of the valve can be repeated.