Rheumatic Fever Flashcards
What causes rheumatic fever?
- Immunologic response occuring as a delayed sequela of GAS infection of the pharynx but not skin
- Attack rate 0.3-3%
What are important predisposing factors for rheumatic fever?
- Family history of rheumatic fever
- Low SES
- Poverty
- Poor hygiene
- Medical deprivation
- Age 6-15 years (peak age 8)
Which valves are affected by rheumatic carditis?
- Mitral (MOST COMMON!) > Aortic > Tricuspid > Pulmonary
What are Aschoff bodies?
- Inflammatory lesions associated with swelling, fragmentation of collagen fibres and alterations in staining characterictics of connective tissue (believed to be necrotic myocardial cells)
What are the diagnostic criteria for rheumatic fever?
- 2 major or 1 major and 2 minor + evidence of antecendent strep infection
- Evidence of GAS infection:
- Positive throat culture or rapid strep antigen test result
- Elevated or rising ASOT
- Major manifestations:
- Joints: Polyarthritis
- Obvious: Carditis
- Nodules
- Erythema marginatum
- Sydenham’s chorea
- Minor manifestations:
- Clinical findings:
- Arthralgia
- Fever
- Lab findings
- Elevated ESR, CRP
- Prolonged PR interval
- Clinical findings:
Describe arthritis associated with ARF
- Large joints (knees, ankles, elbows, wrists)
- Migratory nature
- Swelling, heat, redness, severe pain, tenderness, limited ROM
- Exquisitely sensitive to salicylates; if patients do not reqpons drmaatically to salicylates within 48 hours unlikely to be ARF
What percentage of patients with ARF have carditis?
50%
List signs of carditis in ARF
- Tachycardia out of proportion to fever
- Murmur consistent with MR or AR or both
What is the most common feature of ARF?
- Arthritis
- 70% of cases
What are findings of carditis on echo?
- Pericardial effusion
- Hemodynamically significant MR
- Increased LV dimension
- Impaired LV function
Describe pericarditis in ARF
- Only seen with mitral valve involvement
- Effusion usually small volume and never causes tamponade
What is seen on CXR in ARF?
- Possible to see cardiomegaly, indicative of severity of rheumatic carditis
What physical exam findings are associated with carditis?
- Murmur of MR or AR
- Signs of CHF: gallop rhythm, distant heart sounds, cardiomegaly
- Signs of pericarditis: Friction rub, pericardial effusion, chest pain, ECG changes
What percentage of ARF patients get erythema marginatum?
- < 10 %
Describe arythema marginatum associated with ARF
- Nonpruritic
- Serpiginous or annular eythematous rashes
- Most prominent on trunk and innter proximal parts of extremities
- Never seen on the face
- Evanscent rashes, disappear with exposure to cold and reappear after a hot shower or when patients are bundled in warm blankets
What percentage of ARF patients have subcutaneous nodules?
2-10%
Describe subcutaneous nodules of ARF
- Hard, painless, non pruritic
- Freely moveable
- 0.2-2cm diameter
- Found symmetrically, singly or in clusters
- Extensor surfaces of small and large joints, over scalp, along spine
How long do subcutaneous nodules last for?
- Weeks
- Strongly associated with carditis
In what other conditions do children get subcutaneous nodules?
- Rheumatoid arthritis, 10% of patients involved
What percentage of ARF patients are affected with chorea?
- 15%
- Mostly pre-pubertal girls (8-12 years)
What is the natural history of chorea?
- Begins with emotional lability and personality changes
- Replaced in 1-4 weeks by spontaneous purposeless movements of chorea
- Chorea lasts 4-18 months
- Followed by motor weakness
- Adventitious movements, weakness and hypotonia continue for an average of 7 months before slowly resolving
What is the pathogenesis of chorea?
- anti-neuronal antibodies found in > 90% patients with chorea
- Increased antibody level correlates with severity of chorea
When can arthritis and prolonged PR interval be used as manifestations in the diagnosis of ARF?
- Arthritis cannot be used if there is already arthralgia
- Proloned PR interval cannot be used if there is already carditis
What is the most reliable evidence of recent GAS infection?
- Streptococcal antibody tests
- History of throat infection alone not reliable
- Positive throat cultures or rapid strep antigen tests cannot differentiate between recent infection and chronic pharyngeal carriage
What are the three streptococcal antibody tests?
- Antistreptolysin O titres
- Antideoxyribonuclease B titres
- Slide agglutination test (streptozyme test)
What are exceptions to the Jones criteria?
- Chorea may occur as the sole manifestation of ARF
- Indolent carditis may be the sole manifestation in patients who come to medical attention months after theonset of rheumatic fever
- Occasionally patients with ARF may not fulfill the Jones criteria
What is the differential diagnosis of ARF?
- JRA: would be more suggested by involvement of small joints, symmetrical involvement of large joints without migratory arthritis, pallor of involved joints, indolent course, no evidence of preceeding strep infection, no good response to salicylates within 24-48 hours
- Collagen vascular disease, reactive arthritis (including post strep arthritis), serum sickness, infectious arthritis
- Virus associated acute arthritis (rubella, parvovirus, hep B virus, herpesviruses, enteroviruses) much more common in adults
- Hematologic disorders: sickle cell disease, leukemia
What is the prognosis of ARF?
- Only carditis can cause permanent damage
- Mild carditis resolves in weeks
- Severe carditis can take 2-6 months to resolve
- Arthritis subsides within a few days to several weeks and does not cause permanent damage
- Chorea gradually subsides within 6-7 months and doesn’t cause permanent damage
What investigations should be ordered when ARF is suspected?
- CBC
- ESR
- CRP
- THroat culture
- ASOT
- Second antibody titre
- CXR
- ECG
- Cardio consult + echo
How to manage ARF?
- Benzathine penicillin G 0.6-1.2 million units IM to eradicate streptococci
- Anti-inflammatory therapy (salicylates or steroids) - don’t start until a definite diagnosis is made
- Educate patient and parents about the need to prevent subsequent strep infections with antibiotic prophylaxis
- Bed rest: longer for more severe carditis. Full activity allowed when the ESR has normalized, may be prolonged bed rest for kids with significant cardiac involvement
How to manage CHF due to ARF?
- Best rest
- Prednisone for severe carditis
- Digoxin used cautiously at half the usual dose
- Furosemide
How to manage Sydenham’s Chorea?
- Reduce physical and emotional stress and use protective measures as indicated to prevent physical injury
- Benzathine penicillin G initially for eradication and then for prophylaxis against recurrent infection
- Anti inflammatory agents not needed
- In severe cases: phenobarbitol, haloperidol, VPA, chlorpormazine, diazepam, steroids
