Rheumatic Fever - intrinsic Flashcards
What is rheumatic fever?
Acute RF is:
- an autoimmune disease
- may occur following group A strep throat infection.
It can affect multiple systems, including:
- joints,
- heart,
- brain,
- skin.
Only the effects on the heart –> to permanent illness;
What is ‘chronic rheumatic heart disease?
Chronic changes to heart valves (as a complicaion of repeated bouts of acute rheumatic fever)
What is the prophylactic Tx for repeated bouts of acute rheumatic fever?
long-term penicillin secondary prophylaxis
without this:
- acute RF can recur,
- –> to cumulative damage to cardiac valvular tissue.
What is the cause of rhuematic fever?
- acute RF = autoimmune disease
- is the result of group A streptococcal infection –> an AI response in a susceptible host
Summarise the pathophysiology of rheumatic fever
The interaction between group A strep and a susceptible host
–> AI response directed against:
- cardiac
- synovial
- subcutaneous
- epidermal
- neuronal tissues.
It is believed that both cross-reactive Abs & cross-reactive T cells play a role in the disease.
- Molecular mimicry between group A strep pyogenes antigens and human host tissue is thought to be the basis of this cross-reactivity.
What are the risk factors for rheumatic fever?
- Poverty
- Overcrowded living quarters
- FHx of rheumatic fever
- D8/17 B cell antigen positivity
- HLA association
- Genetic susceptibility
- Indigenous populations; Aboriginal Australian, Asian, and Pacific Islanders
Summarise the epidemiology of rheumatic fever
- Primary episodes of acute RF:
- in children 5-14yr
- rare in people 30+yrs
- 2.4m+ children have rheumatic heart disease worldwide;
- 94% of these are in developing countries
- Worldwide there are 330,000+ new cases of acute RF annualy
- Recurrent episodes
- relatively common in adolescents & young adults
- but uncommon in those 35+yrs
What are the presenting symptoms of rheumatic fever?
- Fever
- Joint pain
- Swollen joints
- Recent sore throat or scarlet fever
-
Chest pain
- symptom of severe carditis
-
SOB
- symptom of severe carditis
-
Palpitations
- rheumatic carditis –> palpitations in associated w advanced heart block
- longstanding rheumatic heart disease + left atrial dilatation –> palpitations associated w AF
- signs of cardiac failure
Describe the joint pain (one of presenting symptoms of RF)
- extreme
- asymmetrical
- may be affected for a period of hours or a couple of days.
most commonly affected joints:
- knees
- ankles
- wrists
- elbows
- hips
What are the characteristics of arthritic pain vs arthralgia?
when accompanied by:
- tenderness
- warmth,
- restricted movement
–> indicates arthritis rather than arthrlagia
What are the signs of rheumatic fever O/E?
-
Carditis
- Mitral regurgitation is the most clinical manifestation of carditis and can be heard as a pan-systolic murmur loudest at the apex
- Pericardial rub
- Signs of cardiac failure
-
Arthritis
- Swollen joints
-
Chorea
- Jerky, uncoordinated choreiform movements
- Inability to maintain protrusion of the tongue
- Milkmaid’s grip
- Erythema marginatum
- Subcutaneous nodules
What is milkmaid’s grip?
- sign of chorea
- rhythmic squeezing when patient grasps the examiner’s hand
How long post-initial infection might rheumatic chorea occur?
It can occur up to 6 months after the initial infection
Describe the rash seen in rheumatic fever
Erythema marginatum
pink serpinginous rash with a well-defined edge
Describe the subcutaneous nodules seen in rheumatic fever
- firm, painless lumps
- 0.5-2cm in diameter
- found mainly over extensor surfaces / bony protuberances
- particularly on the extensor surfaces of the elbows, hands, feet, and over the occiput and upper back
What is the name of the diagnostic criteria for rheumatic fever?
Jones criteria
How many major/minor criteria must be present for a diagnosis of rheumatic fever?
Jones criteria:
presence of recent history of streptococcal infection AND either:
- 2 major OR
- 1 major and 2 minor criteria
What are the major and minor criteria for rheumatic fever?
What is Chronic rheumatic heart disease?
established:
- mitral valve disease OR
- mixed mitral/aortic valve disease,
presenting for the first time
What are the primary investigations for ?rheumatic fever
bloods:
- ESR
- CRP
- WBC count
- blood cultures
- ECG
imaging
- CXR
- echocardiogram
misc.:
- throat culture
- rapid antigen test for group A streptococci
- anti-streptococcal serology
What happens to the PR inverval with age?
- increases with age
- hence must use age-standardised PR interval reference values
What would be the results of the bloods if the pt had rhuematic fever?
ESR - >60mm/hour (low risk pops) or >30mm/hour (moderate-high risk pops)
CRP - > or equal to 28.57 nanomols/L
WBC count – may be elevated
Blood cultures – useful if patient is febrile to exclude bacteraemia
What might the CXR show in rheumatic fever?
may demonstrate
- chamber enlargement AND
- congestive cardiac failure
- What is the use of the echocardiogram when diagnosing rheumatic fever?
- What might it show in rheumatic fever?
- improves specificity of diagnosis
- ~ morphological changes to mitral and/or aortic valves;
- severity of regurgitation (mitral, aortic, and tricuspid);
- pericardial effusion if pericarditis present
What might be the results of the
- throat culture
- Rapid antigen test for group A streptococci
- Anti-streptococcal serology
in a case of rheumatic fever?
- Throat culture
- may grow group A strep
- Rapid antigen test for group A streptococci
- positive
- Anti-streptococcal serology
- above normal range
