Mitral stenosis

Presumed to be a result of rheumatic heart disease.

History of rheumatic fever present in about one third of patients.

Characterized by obstruction to left ventricular inflow at the level of mitral valve due to structural abnormality of the mitral valve.

Other etiologies include congenital mitral stenosis, malignant carcinoid disease, systemic lupus erythematosus, rheumatoid arthritis, mucopolysaccharidoses, Fabry disease, Whipple disease, and methysergide therapy.

Association of atrial septal defect with rheumatic mitral stenosis is called Lutembacher syndrome.

Stenosis of the mitral valve typically occurs decades after acute rheumatic carditis.

Acute infectio leads to formation of multiple inflammatory foci in the endocardium and myocardium.

Over time the valve apparatus becomes thickened, calcified, and contracted, and commissural adhesion occurs, ultimately resulting in stenosis.

Result of thickening of valve leaflets, fusion of mitral commissures, retraction, thickening and fusion of chordae, and valve calcification deposition.

May be a result of congenital disease with chordal fusion or papillary muscle malposition.

Mitral annular calcification may produce a mitral gradient in the elderly and in patients with end-stage renal disease.

Calcium in the mitral annulus invades the mitral leaflet from the annulus inward.

Normal mitral valve orifice area is approximately 4-6 cm2.

As the orifice size decreases from valvular stenosis, the pressure gradient across the mitral valve increases to maintain adequate flow.

Valve-related symptoms occur when the valve area is 2-2.5 cm2 or less.

When the valve area is 2-2.5 cm2 or less moderate exercise or tachycardia may result in exertional dyspnea from the increased transmitral gradient and left atrial pressure.

Severe mitral stenosis occurs with a valve area of less than 1 cm2.

With progressive valve stenosis the resting diastolic mitral valve gradient, and left atrial pressure, increases.

When left atrial pressure rises, transudation of fluid into the lung interstitium occurs and dyspnea at rest or with minimal exertion results.

Hemoptysis may result if the bronchial veins rupture.

With left atrial dilatation the risk for atrial fibrillation and thromboembolism increases, as does pulmonary hypertension.

Pulmonary hypertension may develop from retrograde transmission of left atrial pressure, pulmonary arteriolar constriction, interstitial edema, or changes in the pulmonary vascular bed.

With the development of pulmonary hypertension, right ventricular dilation and tricuspid regurgitation may develop, with elevated jugular venous pressure, liver congestion, ascites, and pedal edema.

Left ventricular end-diastolic pressure and cardiac output are usually normal in the person with isolated mitral stenosis, but as stenosis increases the cardiac output becomes subnormal at rest and fails to increase during exercise.

Approximately one third of patients with rheumatic mitral stenosis have depressed left ventricular systolic function.

The presence of concomitant mitral regurgitation, systemic hypertension, aortic stenosis, or myocardial infarction can also adversely affect left ventricular function and cardiac output.

The prevalence of rheumatic disease is steadily declining with an estimated incidence of 1 in 100,000.

The prevalence of rheumatic disease is higher in developing nations.

A progressive disease consisting of a slow, stable course in the early years.

The disease process accelerates later in life, with a latent period of 20-40 years from the occurrence of rheumatic fever to the onset of symptoms.

Once symptoms develop, it takes almost a decade before they become significant.

Survival is greater than 80% at 10 year, in asymptomatic or minimally symptomatic individuals.

In moderately symptomatic patients 10-year survival is less than 15% in the patient with untreated mitral stenosis.

When severe pulmonary hypertension, mean survival is less than 3 years.

60% of patients with severe untreated mitral stenosis die of progressive pulmonary or systemic congestion.

Patients may suffer from systemic and pulmonary embolism, or infections.

Two thirds of all patients are female.

Onset of symptoms usually occurs between the third and fourth decade of life.

Patients develop embolic episodes that are usually associated with atrial fibrillation.

Compression of the left recurrent laryngeal nerve, and bronchi by the enlarged left atrium may cause hoarseness, and cough, respectively.

Clinical finding of an opening snap that follow S2 due to a stiff mitral valve.

When the LA pressure is low the interval between opening snap and aortic closure sound is long, but shortens as the LA pressure increases and approaches the aortic diastolic pressure.

As stenosis worsens, a localized diastolic murmur occurs with low in pitch, and whose duration increases with severity, is best heard at the apex of the heart with the patient in the left lateral position.

A murmur of mitral regurgitation may accompany the mitral stenosis murmur.

MS in the presence of significant mitral regurgitation percutaneous valvuloplasty or surgical commissurotomy are not effective approaches and valve replacement is the best alternative.

With mild to moderate mitral stenosis left atrial pressures and cardiac output are basically normal and the patient is asymptomatic or minimally symptomatic with exertion, and the valve area is usually between 1.8 cm² and 1.3 cm².

With severe mitral stenosis, the valve area is less than 1 cm², severe pulmonary hypertension is present, low cardiac output and right heart failure predominate, and pulmonary edema is uncommon.

Two clinical syndromes occur: mild to moderte and severe mitral stenosis.

In mild-moderate MS left atrial and cardiac output may be normal and the patient may be asymptomatic or symptomatic with extreme exertion, and the valve area is usually between 1.8 cm2 and 1.3cm2.

With severe MS valve area <1.0 cm, and pulmonary hypertension develops due to secondary stenosis of the pulmonary vasculature with low cardiac output and right heart failure.

Paroxysmal and chronic atrial fibrillation occurs in 50 to 80% of patients.

Increasing heart rate reduces diastolic time and increases mitral gradient and may precipitate pulmonary edema, indicating that maintaining a slow heart rate his pref2242ed.

Echocardiography is the pref2242ed technique for assessing the disease.

A percutaneous valvuloplasty scoring system assigning one-four points to parameters which include mitral leaflet thickening, mitral leaflet mobility, sub mitral scarring, and commisural calcium: Patients with a score of eight or less respond best to balloon valvuloplasty.

Echocardiographic studies can determine left atrial size and an increased size suggests the likelihood of atrial fibrillation and thrombus formation.

Echocardiography symptom evaluation provides most of the needed information, and cardiac catheterization is used to detect associated valvular, and coronary artery disease.

Most patients as a long asymptomatic phase followed by a minor limitations of activity.

Pregnancy with increased cardiac output can precipitate symptoms.

Atrial fibrillation can also precipitate progressive symptoms, and control of rate or restoration of sinus rhythm improves clinical condition.

Patients with atrial fibrillation, even if sinus rhythm can be restored, should be treated with warfarin anticoagulation as 20 to 30% of such patients will have systemic embolization without anticoagulation.

Thromboembolic disease in the presence of only mild to moderate MS should be treated with warfarin before considering surgery.

Indication for surgical intervention includes pulmonary edema, decreased exercise capacity, the presence of pulmonary hypertension with a peak systolic pulmonary artery pressure of greater than 50 mmHg, and the presence of atrial for ablation.

Mitral commissurotomy is primarily done by percutaneous balloon valvulasty with 10 year data showing no outcome difference between open commissurrotomy and percutaneous technique.

Percutaneous mitral valvuplastomy has a mortality rate of <0.5%, and a morbidity rate of 3-5%.

Operative valvuplasty has a mortality rate of of 1-3%.

Repeat valvuloplasty may be an option.

Maze procedure may accompany valvuloplasty to reduce atrial fibrillation.

Mitral valve replacement is indicated when a combination of stenosis and regurgitation exist or the echo score is greater than 8.

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