Rheumatic Fever

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Rheumatic Fever

Rheumatic fever is an inflammatory disease that occurs in children and young adults (the first attack usually occurs at between 5 and 15 years of age as a result of infection with group A streptococci.

Pharyngeal infection with group A streptococcus is followed by the clinical syndrome of rheumatic fever. This is thought to develop because of an autoimmune reaction trig- gered by molecular mimicry between the cell wall M proteins of the infecting Streptococcus pyogenes and cardiac myosin and laminin.

The condition is not due to direct infection of the heart or to the production of a toxin.

It affects the heart, skin, joints and central nervous system

Pathology

All three layersof the heart may be affected.

The characteristic lesion of rheumatic carditis is the Aschoff nodule, which is a granulomatous lesion with a central necrotic area occurring in the myocardium.

Small, warty vegetationsmay develop on the endocardium, particularly on the heart valves.

A serofibrinous effusion characterizes the acute pericarditis that occurs.

The synovial membranes are acutely inflamed during rheumatic fever, and subcutaneous nodules (which are also granulomatous lesions) are seen in the acute stage of the disease.

Clinical features

The disease presents suddenly, with fever, joint pains, malaise and loss of appetite.

Diagnosis relies on the presence of two or more major clinical manifestations or one major manifestation plus two or more minor features.

Revised Jones criteria for the diagnosis of rheumatic fever

Major criteria

Carditis

Polyarthritis

Chorea

Erythema marginatum

Subcutaneous nodules

Minor criteria

Fever

Arthralgia

Previous rheumatic fever Raised ESR/C-   reactive protein Leucocytosis

Prolonged PR intervalon ECG

Plus evidence of antecedent streptococcal infection, e.g. positive throat cultures for group A streptococci, elevated antistreptolysin O titre (250 U) or other streptococcal antibodies, or a history of recent scarlet fever

 

Carditis manifests as:

new or changed heart murmurs

development of cardiac enlargement or    cardiac failure

appearance of a pericardial effusion

ECG   changes of pericarditis, myocarditis, AV block or other cardiac arrhythmias.

Most commonly involved valve is – Mitral valve

Least commonly involved valve is  –  Pulmonary valve

Carey coomb’s murmur

It is a delayed diastolic murmur heard during the course of acute rheumatic fever.

It is a low pitched murmur.

Although it is believed to indicate myocarditis, it is very unlikely that carey coomb’s

murmur is due to myocarditis per se.

No other myocorditis results in a mitral diastolic murmur unless associated with significant mitral regurgitation.

It is most likely due to increased diastolic flow secondary to mitral regurgitation across inflamed cusps.

The dissappearance can be explained by the decrease in the left ventricular size following subsidence of myocarditis, and better function of the mitral valve papillary muscle complex

Non-cardiac features include the following:

Fever.

The arthritis associated with rheumatic fever is classically a fleeting migratory polyarthritis affecting large joints such as the knees, elbows, ankles and wrists.

Once the acute inflammation disappears, the rheumatic process leaves the joints normal.

Sydenham’s chorea (or St Vitus’ dance) is involvement of the central nervous system that develops late after a streptococcal infection.

Sufferers are noticeably ‘fidgety’ and display spasmodic, unintentional choreiform movements.

Speech is often affected.

Skin manifestations include erythema  marginatum, a transient pink rash with slightly raised edges, which occurs in 20%        of cases.

The erythematous areas found         mostly on the trunk and limbs coalesce into crescent- or ring-shaped patches.     

Subcutaneous nodules, which are painless, pea-sized, hard nodules beneath the skin, may also occur.

 

Investigations

Throat swabsare cultured for the group A streptococcus.

Antistreptolysin O titre and antiDNAse B may be elevated.

ESR and CRP are usually high.

 

Treatment

Patients with active arthritis or carditis should be rested in bed.

When the clinical syndrome has subsided (e.g. no pyrexia, normal pulse rate, normal ESR, normal white cell count) the patient is mobilized.

Residual streptococcal infections should be eradicated with oral phenoxymethylpenicillin 500 mg four times daily for 1 week.

This therapy should be administered even if nasal or pharyngeal swabs do not culture the streptococci.

The arthritis of rheumatic fever responds dramatically to NSAIDs.

There is no good evidence that steroids are of benefit, although some experts give high-dose prednisolone if there is severe carditis.

Recurrences are most common when persistent cardiac damage is present, and are preven- ted by the continued administration of oral phenoxymethyl- penicillin 250 mg twice daily or intramuscular benzathine penicillin G 1.2 million units monthly until the age of 20 years or for 5 years after the latest attack

Erythromycin is used if the patient is allergic to penicillin.

 



 


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