Cardiac Path Online

Pathology of Rheumatic Fever And Rheumatic Heart Disease

Dr Sampurna Roy MD

 

                                                                                                                      

 

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.

-Etiology:

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 ;

Subcutaneous nodules.

The minor manifestations include -

A previous history of rheumatic fever ;

Arthralgia ;

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.

Causes of death in rheumatic fever and rheumatic heart disease:

Cardiac failure ;  

Infective endocarditis;

Embolism (involve brain followed by the kidneys, spleen and lungs) ;  

Sudden death occur as a result of obstruction of the mitral valve orifice by a ball thrombus in the left atrium or as a result of coronary ischemia associated with aortic stenosis;

Thrombophlebitis of leg veins and pulmonary embolism ;

Death may occur from various other conditions such as pneumonia.

Extracardiac Lesions:

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.

Pathological Features of Rheumatic Heart Disease:

Acute Rheumatic Carditis:

Acute rheumatic heart disease is a pancarditis, involving all three layers of the heart.

The myocarditis is most typically involved in the acute stage of the disease.

A diffuse non-specific myocarditis is present in some cases, together with a unique type of interstitial inflammation, the Aschoff body.

Related post: Pathology of Aschoff body

The main cause of death in the acute stage of rheumatic heart disease is heart failure from the myocarditis.

Also seen during the acute stage of the disease is a prominent pericarditis, characterized by tenacious deposits of fibrin that resemble the shaggy irregular surfaces of two slices of buttered bread that have been pulled apart- the so called bread-and-butter appearance.

The pericarditis may be recognized clinically by a friction rub, but the involvement has little functional effect and only rarely leads to constrictive pericarditis.

During the acute stage, an endocarditis involves mainly the valves, which show a finely nodular "verrucous" appearance at the line of closure.

Areas of focal collagen degeneration in the valve are surrounded by inflammation with ulceration of the valve endocardial surface and deposition of fibrin on the surface.

Chronic Rheumatic Heart Disease:

A patient who has has an attack of rheumatic fever is more susceptible to recurrent episodes following infections by beta-hemolytic streptococci.

Such recurrent attack result in repeated progressively increasing damage to the heart valves.

Thus in chronic recurrent rheumatic heart disease the valve involvement, which was of little clinical significance during the acute attack, becomes the major problem. For example the mitral valve which is most frequently and severely involved valve, shows conspicuous, irregular thickening and calcification of its leaflets, often with fusion of its commissures  and thickening and fusion of the chordae tendineae.

As a result the valve is often severely stenotic and when viewed from the atrial aspect has a narrowed orifice described as having a "fish mouth" appearance.

The aortic valve, the second most commonly involved valve, shows typical fusion of the commissures and later pronounced thickening and calcification of the cusps, with resulting stenosis or insufficiency.

The tricuspid valve is similarly involved, although less frequently than the aortic and mitral valves and the pulmonary valve is the least frequently involved.

The subendocardial collections of Aschoff nodules, usually  in the left atrium, induce thickenings called MacCallum plaques (patch).

Further reading:

The worldwide epidemiology of acute rheumatic fever and rheumatic heart disease.

Giant left atrium mimics massive pleural effusion in rheumatic heart disease.

Rheumatic disease mimicking an infiltrative mass of the mitral valve.

Clinical and echocardiographic features of children with rheumatic heart disease and their serum cytokine profile.

Adhesion molecule expression and ventricular remodeling in chronic rheumaticheart disease: a cause or effect in the disease progression--a pilot study.

Cardiac necklace in rheumatic heart disease.

Rheumatic mitral valve repair: 22-year clinical results.

Ongoing inflammation in children with rheumatic heart disease.

Natural history of aortic valve disease following intervention for rheumatic mitral valve disease.

"MacCallum Plaque of the Heart": A Medicolegal Case.

Case 04/12: a 44-year-old male with rheumatic valvular heart disease with multiple previous surgeries of aortic valve replacement admitted for treatment of congestive heart failure

 

Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)


 

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