Cardiac Path Online
Pathology of Rheumatic Fever And Rheumatic Heart Disease
Rheumatic heart disease is the
result of cardiac involvement by rheumatic fever.
Related post: Pathology of Aschoff body
Rheumatic fever occurs equally in both sexes and at all ages, but it is more common in children with the peak incidence occuring between ages 5 and 15 years.
The exact etiology of rheumatic fever is still controversial.
The disease occurs after a latent period of two to three weeks following an infection with a group A beta-hemolytic streptococcus, typically a pharyngitis.
Streptococci are considered the cause of the pharyngitis, because of elevated titres of antibodies to streptococcal antigens, such as streptolysin O, hyaluronidase or streptokinase in the serum.
The more severe the initial streptococcal infection, the greater the chance of subsequent rheumatic fever.
Some streptococcal antigens cross-react with cardiac antigen. This raises the possibility of an autoimmune etiology.
There seems to be an additional hereditary factor for susceptibility to rheumatic fever after streptococcal infection.
- Clinical diagnosis:
The clinical diagnosis of rheumatic fever is made when two major or one major and two minor criteria - Jones Criteria, are met.
If this diagnosis is supported by evidence of a preceding streptoccocal infection, the probability of rheumatic fever is high.
The major clinical manifestations include -
Carditis (murmur, cardiomegaly, pericarditis, and congestive heart failure) ;
Erythema marginatum ;
Migratory large joint polyarthritis ;
Sydenham chorea ;
The minor manifestations include -
A previous history of rheumatic fever ;
Certain laboratory tests indicative of an inflammatory process. Example: Elevated sedimentation rate, positive test for C-reactive protein, leukocytosis and electrocardiographic changes.
- Fate of the patients with rheumatic fever:
- Complete recovery after an acute attack of rheumatic fever is possible.
- Adhesive pericarditis, which follows the fibrinous pericarditis of the acute attack, almost never results in constrictive pericarditis.
- Most significant late result of rheumatic fever is scarring of the heart valve.
- There is increased susceptibility to the localization of infectious agents on the heart valves.
The irregular scarred nature of the valves provides a suitable environment to bacteria that would originally pass by.
The organism settle down to establish bacterial endocarditis.
Because bacteremia frequenly follows a tooth extraction or urethral catheterization, a person who has prior diagnosis of rheumatic heart disease should be treated prophylactically with penicillin before performing these procedures.
- Mural thrombi can form in the atrial or ventricular chambers and give rise to thromboembolic and infarction of various organs.
Atrial thrombosis occurs in about 40% of patients with rheumatic valvular disease.
Rarely a large thrombs in the left atrial appendage develops a stalk and acts as a ball valve that obstructs the mitral valve orifice.
Subcutaneous nodules : Painless nodules occur in wrist, elbows, ankles and knees. Nodules occur in children and last for 4 to 6 days unlike rheumatoid nodules which may persist for months or years and may be painfull and tender.
Microscopic features: Consist of a central core of fibrinoid necrosis surrounded by a zone of radially palisading histiocytes and fibroblasts.
- Arteritis :
There is coronary artery inflammation-rheumatic arteritis ;
- Polyarthritis :
Synovial membrane and the periarticular connective tissues are the sites of hyperemia, edema, neutrophilic infiltration, fibrinoid change and necrosis, followed by granulomatous change ;
- Lesions in Lungs and Pleura :
- Pleuritis ;
- Pleural effusion ;
- Rheumatic pneumonia ;
- Lungs are usually congested , hemosiderin-laden heart failure cells are seen within alveoli, together with fibrosis of the alveolar septal walls ;
- In addition, there is usually some pulmonary vascular change, principally muscular and intimal arteriolar thickening.
- Right Ventricular Hypertrophy :
Cor pulmonale may develop as a result of a reactive pulmonary hypertension ;
- Lesions of the central nervous system :
Sydenham's chorea - There is disordered and involuntary movements of the trunk and extremities.
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