MITRAL STENOSIS
This is the most common single valve disorder to follow rheumatic fever, and about 65% of cases occur in females. The valves become thickened and stiff, and ultimately calcium deposits form on the valve leaflets. Since the function of the mitral valve is to direct and control blood flow from the left atrium to the left ventricle, eventually, this flow becomes markedly restricted.
Ten or more years may elapse between the original case of rheumatic fever and the development of symptoms from mitral stenosis, although a physician may suspect the disease much earlier from its characteristic, if sometimes subtle, murmur. Thus, young adults are the typical patients.
Symptoms
Over a period of 4 to 8 years, the patient notes shortness of breath as the heart is unable to drain the lungs adequately through the narrowed mitral opening. First noted only after exercise, this later becomes evident even at rest. As pressure builds in the lungs, blood vessels burst, and coughing of blood may occur. Finally all the symptoms of congestive heart failure may ensue.
During the process, the left atrium enlarges markedly, visible on x-ray, and noted on exam. Rhythm disturbances, notably atrial fibrillation, occur. Finally, shock may ensue, leading to death if untreated.
Diagnosis
A combination of history, typical or worrisome murmur, signs of heart enlargement and irregular rhythm are usually the first clues, and echocardiography confirms the diagnosis. Cardiac catheterization is often done prior to treatment to better quantify the situation.
Treatment
In the early stages, avoidance of heavy exertion, and the use of salt restriction are important; the latter avoids fluid accumulations which may further strain the struggling heart. Diuretics such as hydrochlorothiazide, furosemide, and others are added as needed. Heart rhythm stabilizing drugs are useful in some cases, including quinidine, propranolol, and others. In some cases, blood clots form on the rough and thickened valve, and break off, lodging in the arteries of the body; anticoagulants such as warfarin are useful in these cases.
Surgical treatment of the diseased valve is indicated when the symptoms become dangerous or severely impair the daily life of the patient. This may involve simple stretching of the narrowed orifice, or total replacement of the valve with an artificial device. In major centers, such surgery has a mortality of under 2%. Current thinking suggests that the survival long-term is better if replacement is done before the occurrence of severe symptoms. This is a highly specialized area where the surgeon, cardiologist, and patient must consider many variables. Over two thirds of patients operated upon are alive 10 years later, and the mean age is in the 50's at the time of surgery. Thus there is a reasonably good expectation for such patients who previously had almost no chance for survival.
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