In normal adults the Mitral valve between the left atrium and left ventricle, has an orifice of 4-6 sq.cm. When the orifice is less than half of the normal, blood flow between left atrium and left ventricle is significantly obstructed. A characteristic finding of mitral stenosis is a localized middiastolic murmur low in pitch whose duration varies with the severity of the stenosis and the heart rate. Because it is thickened, the valve opens in early diastole with an opening snap. The sound is sharp, is widely distributed over the chest, and occurs early after A2 in severe and later in milder varieties of mitral stenosis. In severe mitral stenosis with low flow across the mitral valve, the murmur may be soft and difficult to find, but the opening snap can usually be heard. If the patient has both mitral stenosis and mitral regurgitation, the dominant features may be the systolic murmur of mitral regurgitation with or without a short diastolic murmur and a delayed opening snap.
Mitral stenosis is a narrowing of the orifice of the mitral valve of the heart . In mitral stenosis, blood flow through the narrowed valve opening is reduced. The mitral valve lies between the left atrium (the heart's upper chamber) and the left ventricle (the heart's lower main pumping chamber). The enlarged left atrium often beats rapidly in an irregular pattern (a disorder called atrial fibrillation). As a result, the heart's pumping efficiency is reduced. The reason the blood flows in the proper direction is that, during this phase of the cardiac cycle, the pressure in the left ventricle is less than the pressure in the left atrium, and the blood flows down the pressure gradient . Patients often do not recall a history of rheumatic fever, and clinically apparent mitral stenosis frequently does not develop for more than 20 years after such an episode. Less common etiologies of mitral stenosis include infective endocarditis, severe calcification of the mitral annulus, tumors, systemic lupus erythematosus, and carcinoid. This in turn means there is a reduced amount of blood that is pumped out into the body from the left ventricle.If surgery is indicated, a cardiac surgeon meets with the patient to thoroughly discuss surgical options and, in most cases, can perform the surgery the following day -- if that is the patient's preference. Because Mayo Clinic is a major medical center that conducts clinical trials and research on various aspects of heart valve disease, some patients may be eligible to participate in trials or take part in research programs at Mayo Clinic.
Mitral stenosis is usually caused by rheumatic involvement of the mitral apparatus. As a result, the volume and pressure of blood in the left atrium increases, and the left atrium enlarges. MS obstructs blood flow into the LV, elevating left atrial pressure in proportion to severity of the stenosis.The normal mitral valve is a complex apparatus composed of an annulus and two leaflets that are attached by chordae tendineae to two papillary muscles. This, in turn, restricts pulmonary venous return to the left atrium, elevating pulmonary vascular and, consequently, right heart pressures. If mitral stenosis is severe, pressure increases in the blood vessels of the lungs, resulting in heart failure with fluid accumulation in the lungs and a low level of oxygen in the blood. In normal cardiac physiology, the mitral valve opens during left ventricular diastole , to allow blood to flow from the left atrium to the left ventricle . Left untreated, mitral stenosis will damage the heart, cause irregular heartbeats and possibly heart failure or other serious complications, including stroke, heart infection, pulmonary edema (water on the lungs) and blood clots. This obstruction results in the development of a pressure gradient across the valve in diastole and causes an elevation in left atrial and pulmonary venous pressure. If you have mitral stenosis, the narrowed valve can not open properly and obstructs the flow of blood from the left atrium to the left ventricle. In the case of mitral stenosis, the valve does not open completely, so the left atrium has to have a higher pressure than normal to have the blood overcome the increased gradient caused by the mitral valve stenosis.
Causes of Mitral Stenosis
The common Causes of Mitral Stenosis :
- Deposits of calcium ('calcification') in parts of the valve. This sometimes occurs in older people.
- Mitral stenosis prevents the valve from opening properly and blocks the blood flow from the left atrium to the left ventricle.
- As the valve area becomes smaller, less blood flows forward to the body.
- The atrium swells as pressure builds up and blood may flow back into the lungs, resulting in pulmonary edema (fluid in the lung tissue).
- Infection of the valve (endocarditis).
- A complication of various uncommon diseases.
- However, prevalence of MS in offspring of family members (especially the mother) with left ventricular outflow tract obstruction is increased.
- Congenital mitral stenosis is more often part of a complex heart deformity.
- Symptoms may begin with an episode of atrial fibrillation or may be triggered by pregnancy or other stress on the body such as infection (in the heart, lungs, etc.) or other cardiac disorders.
Symptoms of Mitral Stenosis
Some are common Symptoms of Mitral Stenosis :
- Shortness of breath, especially with physical exertion (exercise) or when the person lies down
- Swollen feet or ankles
- Increases with activity, decreases with rest
- May have blood in the sputum ( hemoptysis )
- Swelling of feet or ankles
- Coughing up blood stained sputum may occur due to the congestion of blood and fluid in the lungs.
- Radiates to the arm, neck, jaw, or other areas
- Sensation of feeling the heart beat ( palpitations )
- Fatigue , tired easily
- Chest pains (angina) may develop if there is a reduced blood flow to the coronary arteries.
Treatment of Mitral Stenosis
Mitral stenosis may be present for a lifetime with few or no symptoms, or it may become severe in a few years. In most cases, there is a long asymptomatic phase, followed by subtle limitation of activity. Pregnancy and its associated increase in cardiac output and the transmitral pressure gradient often precipitate symptoms. The onset of atrial fibrillation often precipitates more severe symptoms, which usually improve with control of the ventricular rate or restoration of sinus rhythm.
Here is the list of the methods for treating Ischaemic Mitral Stenosis :
- ACE Inhibitors are medicines which help to reduce the amount of work the heart does and ease symptoms of heart failure.
- Warfarin ('anticoagulation') is usually advised if you develop atrial fibrillation. This helps to prevent blood clots from forming.
- Valve repair (valvotomy) may be an option in some cases.
- Some patients may need heart surgery to repair or replace the valve.
- Replacement valves can be made from different materials, some of which may last for decades and others which can wear out and require replacement.
- During monitoring, if your doctor detects increased pressure in your heart and lungs, increased narrowing of the valve, or if your symptoms become severe, your mitral valve will need to be repaired or replaced.
- A balloon on the tip of the catheter is inflated, widening the mitral valve and improving blood flow.
- Patients with chronic uncontrolled atrial tachyarrhythmias should be on anticoagulant therapy.
- This procedure is less likely to work in patients with severely damaged mitral valves.
- Patients with associated congenital cardiac anomalies are at a higher risk of early death after mitral valve surgery.