What are the causes of rheumatic endocarditis

The main cause for this disease is the betahaemolytic Streptococcus of group A, which is found in common infectious sites such as the mouth; in dental granulomas, dental abscesses, paradontosis, and other infections such as chronic tonsillitis.  

The streptococcal theory is based on: 

  1. Bacteriological data. betahaemolytic Streptococcus was isolated from extracting material from sites of infection.  

  1. Immunological data. Streptococcus bears extracellular and intracellular antigens. Extracellular antigens include streptolysin, which is a protein that increases in levels during rheumatism, streptokinase which is a phosphorylating enzyme, streptodornase, hyaluronidase, which is another enzyme found in elevated levels in patients suffering from rheumatism. Intracellular antigens include: polysaccharides, protein M.  

  1. Epidemiological data. It has been noticed that an increase in patients suffering from chronic tonsillitis is correlated with an increase in patients suffering from acute articular rheumatism. 

  1. Therapeutic data. Using antibiotics to treat streptococcal angina or using antibiotics with slow release into the bloodstream leads to a decrease of cases of rheumatism.  

How is rheumatic endocarditis caused?

Endocarditis may come in different forms.  

  1. Diffuse form: which is accompanied by exudative and proliferative changes, but without any damage to the valve surfaces and without the formation of any thrombi. At the onset, the valves appear edematous, and later on they become sclerotic, becoming thicker and shorter.  
  2. Verrucous form: which is accompanied by damage to the epithelia at the edges of the valves and thrombi in the form of verrucae.  

Both of these forms involve degeneration of the tissue and may lead to fibrous endocarditis, which causes the valve tissue to become rigid and fibrous, lacking elasticity. This disease may occur several times, hence, recurrent endocarditis is a potential diagnosis. In these cases, the damage to the valves is even greater, the damages to the valves are superposed.  

Medically Reviewed by a doctor on 28 Mar 2018
Medical Author: Dr. med. Diana Hysi