Acquired: Rheumatic fever or Rheumatic Heart disease (RHD) is the major cause of Acquired Mitral stenosis, especially in developing countries. A research study done in a rural Indian school showed that 5.7% of their students had clear evidence of rheumatic heart disease, 23% of students had streptococcal growth from their throat swab cultures. This study concluded that overcrowded and unhygienic living conditions were the most important reason of its incidence. Voluntary agencies and government should take active part in removing the blight of rheumatic heart disease.
Complication of the “group ‘A’ streptococcal” infection of the throat causes rheumatic fever, which is the inflammation of the body organs. It mainly affects the heart and the joints. A child with untreated strep throat has up to 3% chance of developing rheumatic fever and about 50% of these children develop it again after another streptococcal infection.
Symptoms usually occur weeks later the infection disappears. Heart inflammation may not show itself for several years. Although the inflammation disappears, it can severely damage the mitral valve. About 30-70% of patients with heart inflammation develop rheumatic heart disease depending on the severity of inflammation. Scarring and calcification of the mitral cusps occur. This leads to a smaller orifice or opening causing “Mitral Stenosis”.
The United States widely uses antibiotics to treat early streptococcal infection, thus has a lower incidence of rheumatic fever.
Research shows only 1 out of 100,000 people are diagnosed with rheumatic heart disease in the U.S., whereas about 100-150 out of 100,000 people have RHD in India.
Evidently, prevention helps. Better housing, nutrition, sanitary environment and ample child health care is required to fight rheumatic fever in India and other developing countries. Education and public awareness is crucial.
Other acquired causes of Mitral Stenosis are systemic lupus erythematosus (SLE), rheumatoid arthritis, carcinoid causes, and some mucopolysaccharidoses. These pathological conditions cause diffuse connective tissue inflammation.