Rheumatic Fever

Question 1

What causes rheumatic fever?

Answer 1

• Immunologic response occuring as a delayed sequela of GAS infection of the pharynx but not skin
• Attack rate 0.3-3%

Question 2

What are important predisposing factors for rheumatic fever?

Answer 2

• Family history of rheumatic fever
• Low SES
  
  • Poverty
  • Poor hygiene
  • Medical deprivation
• Age 6-15 years (peak age 8)

Question 3

Which valves are affected by rheumatic carditis?

Answer 3

• Mitral (MOST COMMON!) > Aortic > Tricuspid > Pulmonary

Question 4

What are Aschoff bodies?

Answer 4

• Inflammatory lesions associated with swelling, fragmentation of collagen fibres and alterations in staining characterictics of connective tissue (believed to be necrotic myocardial cells)

Question 5

What are the diagnostic criteria for rheumatic fever?

Answer 5

• 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

Question 6

Describe arthritis associated with ARF

Answer 6

• 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

Question 7

What percentage of patients with ARF have carditis?

Answer 7

50%

Question 8

List signs of carditis in ARF

Answer 8

• Tachycardia out of proportion to fever
• Murmur consistent with MR or AR or both

Question 9

What is the most common feature of ARF?

Answer 9

• Arthritis
• 70% of cases

Question 10

What are findings of carditis on echo?

Answer 10

• Pericardial effusion
• Hemodynamically significant MR
• Increased LV dimension
• Impaired LV function

Question 11

Describe pericarditis in ARF

Answer 11

• Only seen with mitral valve involvement
• Effusion usually small volume and never causes tamponade

Question 12

What is seen on CXR in ARF?

Answer 12

• Possible to see cardiomegaly, indicative of severity of rheumatic carditis

Question 13

What physical exam findings are associated with carditis?

Answer 13

• 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

Question 14

What percentage of ARF patients get erythema marginatum?

Answer 14

• < 10 %

Question 15

Describe arythema marginatum associated with ARF

Answer 15

• 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

Question 16

What percentage of ARF patients have subcutaneous nodules?

Answer 16

2-10%

Question 17

Describe subcutaneous nodules of ARF

Answer 17

• 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

Question 18

How long do subcutaneous nodules last for?

Answer 18

• Weeks
• Strongly associated with carditis

Question 19

In what other conditions do children get subcutaneous nodules?

Answer 19

• Rheumatoid arthritis, 10% of patients involved

Question 20

What percentage of ARF patients are affected with chorea?

Answer 20

• 15%
• Mostly pre-pubertal girls (8-12 years)

Question 21

What is the natural history of chorea?

Answer 21

• 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

Question 22

What is the pathogenesis of chorea?

Answer 22

• anti-neuronal antibodies found in > 90% patients with chorea
• Increased antibody level correlates with severity of chorea

Question 23

When can arthritis and prolonged PR interval be used as manifestations in the diagnosis of ARF?

Answer 23

• Arthritis cannot be used if there is already arthralgia
• Proloned PR interval cannot be used if there is already carditis

Question 24

What is the most reliable evidence of recent GAS infection?

Answer 24

• 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

Question 25

What are the three streptococcal antibody tests?

Answer 25

* Antistreptolysin O titres * Antideoxyribonuclease B titres * Slide agglutination test (streptozyme test)

Question 26

What are exceptions to the Jones criteria?

Answer 26

* 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

Question 27

What is the differential diagnosis of ARF?

Answer 27

* 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

Question 28

What is the prognosis of ARF?

Answer 28

* 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

Question 29

What investigations should be ordered when ARF is suspected?

Answer 29

* CBC * ESR * CRP * THroat culture * ASOT * Second antibody titre * CXR * ECG * Cardio consult + echo

Question 30

How to manage ARF?

Answer 30

* 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

Question 31

How to manage CHF due to ARF?

Answer 31

* Best rest * Prednisone for severe carditis * Digoxin used cautiously at half the usual dose * Furosemide

Question 32

How to manage Sydenham's Chorea?

Answer 32

* 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