Incidence of mitral stenosis is same as that of rheumatic fever. But it occursS cartter in tropical countrie pafticularly in TIndia In the western world, Rheumati incidence is gradually declining but it is not so in tropica and sub-tropical countries.
PATHOLOGY | MITRAL STENOSIS
In active rheumatic valvulitis, the, damage of the valves mostly occurs at the line of apposition (which is slightly inside the edge of valves) due to trauma during repeated closure Fibrin and platelets are deposited in that line, ultimately fibroblastic prolifefation facilitates adhesion between the valvesThe scarring of the valves may be followed by całcification in some cases The chordae tendineae, papillary muscles and fibrous ring are also involved in the rheumatic process leading to scarring and rigidity.The mitral opening may be like a slit as in ‘button hole or may be further narrowed down to a ‘funnel shape’ due to shortening of chordae The normal mitral orifice area is 5 cm2 When it becomes 2.5 cm symptoms appear after physical exertion but symptoms appear even at rest when the orifice area becomes critical, i.e., 1 cm2, which occurs in 10%-15 % of cases. In moderate mitral stenosis the valve area is <1 cm2
The resistance of narrow lumen of mitral orifice gives rise to high left atrial pressure, more so in tachycardia when diastolic ventricular filling time becomes shorter. The high pressure in left atrium gives rise to left atrial hypertrophy and dilatation and transmitted to pulmonary veins and to pulmonary capillaries. The pulmonary arterial pressure also rises. The increased pulmonary vascular resistance is responsible for decreased pulmonary blood flow to the lung bases and redistribution of blood flow occurs in the upper lobe. With the relief of stenosis this resistance becomes reversible. In a few cases the pulmonary arterioles become narrowed which in turn leads to increased pulmonary arterial pressure. All these put great strain to right ventricle which hypertrophies and eventually dilates leading to failure. | MITRAL STENOSIS
These usually develop insidiously after 3-4 years of acute rheumatic fever but may be delayed as late as 50 years. Sex: Females usually predominate (75%)
Cardiovascular System | MITRAL STENOSIS
Though mitral stenosis is a progressive disease in absence of mitral valvotomy its prognosis is unpredictable. Disorganisation and calcification of the mitral valve, progressive increased pulmonary resistance, chronic right-sided heart failure with cardiac cirrhosis are ominous signs. In carefully selected cases mitral valvotomy influences the prognostic outcome.
Functional mitral mid-diastolic murmur:
OS, presystolic accentuation of the diastolic murmur and diastolic thrill are absent. Features of original disease will also be present.
Opening snap, palpable first heart sound and diastolic thrill are absent over the mitral area. Echocardiography is very much helpful. Aortic regurgitation murmur is present over aortic area.
Conducted murmur of aortic incompetence:
This is not rumbling but blowing in character, occupies early part of diastole, not associated with opening snap or diastolic thrill.
Absence of opening snap, diastolic thrill, palpable first heart sound over the mitral area.Wide and fixed splitting of the S2 over pulmonary area, no evidence of enlargement of left atrium in the X-ray and ECG. But later may show incomplete or complete RBBB.
Left atrial myxoma
Constitutional symptoms like fever, weight loss, weakness together with high ESR, anemia, hypergamma-globulinemia may be present. Systemic embolisation, opening snap (false opening snap-tumour plop may be present), palpable first heart sound, diastolic thrill over, the mitral area are absent. Evidence of rheumatic valve disease is lacking. Murmur changes with change of posture. Left atrial angiography (which may precipitate embolisation) may show a lobulated filling defect and echocardiogram characteristically shows diastolic mass of echoes behind the mitral valve.
Echocardiogram is most helpful in the diagnosis
Primary pulmonary hypertension:
This is seen in young females. Opening snap, mitral diastolic thrill and typical mitral stenotic murmur or left atrial enlargement in X-ray are absent. Normal left atrial and pulmonary wedge pressure are seen.
In age groups below 20 years or with mild mitral stenosis or where surgery is contraindicated conservative medical treatment is advised. This includes treatment of complications like chest infection, bacterial endocarditis by antibiotics; cardiac arrhythmia by antiarrhythmic drugs, embolisation by anticoagulants and heart failure by diuretics and digitalis. If the rheumatic process is persistent it should be treated in the usnal way. Prophylactic chemotherapy should also be continued both for rheumatic fever and bacterial endocarditis. The surgical treatment is indicated in the following conditions:
There are four operative procedures:
Though closed mitral valvotomy can be performed yet many surgeons prefer open valvotomy. In cases of combined stenosis with regurgitation in presence of grossly distorted and calcified valves, prosthetic valve replacement is indicated. Artificial valves may work efticiently for more than 20 years. Anticoagulants are to be continued for prevention of thrombus formation.
Although long-term data are not yet available, balloon valvuloplasty will be as effective as heart surgery.
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