Rheumatic Fever Flashcards
define rheumatic fever
an inflammatory mutlisystem disorder, occuring following group A beta- haemolytic streptococci ( GAS) infection
Always caused by infection of pharynx- NOT HEART autoimmune infection
what are the risk factors for rheumatic fever?
genetic susceptibility ( HLA class II) Severity of infection and magnitude of immune response
○ Other factors which would predispose to step infection itself: ▪ Age (4-9 yrs)
▪ Sex (more common in females)
▪ Seasonality (winter and spring peak)
Economic factors e.g. poverty, urban environ and crowding
explain the aetiology of rheumatic fever?
Pathogenic mechanisms remain incompletely understood
Pharyngeal infection with Lancefield group A beta-haemolytic streptococci triggers rheumatic fever 2-4 weeks later in the susceptible 2% of the population
An antibody to the carbohydrate cell wall (GAS antigens) of the streptococcus cross-reacts with valve tissue (antigenic mimicry of the bacteria) and may cause permanent damage to the heart valves – basics the bacteria would grow by mimicking human antigens on its surface and an antibody is produced against this by the immune system so antibodies would be against myocardium, which would cause carditis (inflamed myocardium) => BP falls
Think child with sore throat and then gets a fever and cardiac signs; if elderly has a murmur ask if they had rheumatic fever as a child
summarise the epidemiology of rheumatic fever?
used to have outbreaks before penicillin- especially in children ( more common in females)
common in developing countries->inreasingly countries but increasing but increasingly rare in the west
peak incidence between 5 and 15
mean incidence 19/100,000
what are the presenting symptoms of rheumatic fever?
2-5 weeks after pharyngeal GAS infection
recent sore throat or scarlet fever
general
- malaise
- fever
- anorexia
joint
- painfully, swollen
- reduced movement/ function
cardiac- symptoms of severe carditis
- breathlessness
- chest pain
- palpitations
how is the diagnosis for rheumatic fever made?
revised Jones criteria
must be evidence of recent strep infection + 2 major criteria or 1 major + 2 minor criteria
outline evidence of GAS infection?
Positive throat culture – but usually negative by the time symptoms occur
Rapid streptococcal antigen test +ve
Elevated/rising streptococcal antibody titre
Recent scarlet fever
what are the major criteria for rheumatic fever?
CASES
Carditis: tachycardia, murmurs (mitral/aortic regurgitation), pericardial rub, cardiomegaly, conduction defects, signs of cardiac failure
Arthritis: usually affects larger joints (antibodies also made against joints)
Subcutaneous nodules: small firm painless nodules seen on extensor surfaces, joints and tendons
Erythema marginatum: geographical-type rash with red, raised edges and clear centre mainly on trunk and proximal limbs (antibodies made against the skin)
Sydenham’s chorea: rapid, involuntary, irregular movements with flowing/dancing quality (due to antibodies also made against brain) - also known as servitus dance
look our for features of mitral stenosis and aortic stenosis-> if you hear mitral and aortic stenosis–> whether they had rheumatic fever when they are younger
what are the minor criteria ( PRAPP)
Pyrexia
Raised ESR/CRP
Arthralgia (only if arthritis not present as major criteria)
Prolonged PR interval (only if carditis not present as major criteria)
Previous rheumatic fever
What are the appropriate investigations for rheumatic fever and interpret the results?
Bloods: FBC (inc WCC – may be elvated), inc elevated ESR/CRP, rising antistreptolysin O titre
Throat swab: culture for GAS, rapid streptococcal antigen test
Histology: Aschoff bodies (granuloma with giant cells) and Anitschkow cells (enlarged macrophages with ovoid, wavy, rod-like nucleus)
ECG: saddle-shaped ST elevation and PR segment depression (features of pericarditis), arrhythmias
Prolonged PR interval is a minor criterion of acute rheumatic fever
CXR – chamber enlargement, congestive cardiac failure
Echocardiogram: pericardial effusion, myocardial thickening or dysfunction, valvular dysfunction, mitral/aortic valves
Anti-streptococcal serology – above normal range
describe the ECG for rheumatic Heart Fever?
saddle-shaped ST elevation and PR segment depression (features of pericarditis), arrhythmias
Prolonged PR interval is a minor criterion of acute rheumatic fever
