rhuematic fever

Question 1

define

Answer 1

Rheumatic fever is an inflammatory disease which follows infection with group A beta hemolytic streptococci, affecting the heart, skin, joints and central nervous system.

Rheumatic fever develops following an immunological reaction to recent (2-6 weeks ago) Streptococcus pyogenes infection.

[It is caused by an inappropriate immune response to streptococcal antigens.]

Question 2

epi

Answer 2

peak incidence: 5-15 yrs

rare in west, common in developing world

mortality from initial attack - less than 1%

Question 3

pathogenesis

Answer 3

There are two theories concerning the pathogenesis of rheumatic fever (RF):

Cross-reactive antibodies:

• clear association with previous streptococcal infection
• anti-viral titres are often elevated - antistreptolysin O antibodies
• streptococci are not directly involved as lesions are sterile
• the more serious the streptococcal infection, the more likely is the development of RF, on average 3% of all streptococcal pharyngitides will cause RF
• all recurrences of RF are preceded by strep infection
• recurrence rate range from 5-50%

Autoimmunity:

• streptococcal infection stimulates the production of antibodies which react with the heart but not with the streptococci
• autoantibodies are present in Aschoff bodies

Question 4

diagnosis + s/s

Answer 4

Diagnosis is based on evidence of recent streptococcal infection accompanied by:

2 major criteria or

1 major with 2 minor criteria

Evidence of recent streptococcal infection

• ASOT > 200iu/mL
• history of scarlet fever
• positive throat swab
• increase in DNase B titre

Major criteria

• erythema marginatum [2-10%]
• Sydenham’s chorea [10%]- occurs late, grimacing, clumsy, hypotonia, stops in sleep
• polyarthritis [75%]
• carditis [60%]
  
  • pericarditis: chest pain, friction rub
  • myocarditis: sinus tachy, AV block, HF, high CK
  • endocrditis: murmur [AR/MR]
  • apical systolic murmur may be only symptom
  • conduction defects
• subcutaneous nodules- painless nodules on extensor surfaces esp elbows

Minor criteria

• raised ESR or CRP
• pyrexia [pt deels malaise, anorexia]
• arthralgia (not if arthritis a major criteria)
• prolonged PR interval

Question 5

ix

Answer 5

1. blood tests - ESR, CRP and antistreptolysin titres are high, FBC [raised WCC]
2. thorat swab- culture for GAS, rapid streptococcal Ag test
3. ECG - prolonged P-R interval [In first degree heart block there is a delay in the conduction pathway from the sino-atrial node to the ventricles]
4. echocardiography may show vegetations or a pericardial effusion/ valvular dysfunction

Question 6

mx

Answer 6

1. strict bed rest - till CRP normal for 2 weeks
2. abx: benpen IV stat, then continue for 10 d with oral penecillin v
3. analgesia: for carditis/arthritis
4. add oral pref if severe carditis
5. chorea- controlled with bdxpine [diazepam]/haloperidol
6. valve surgery - if valvualr disease cant be managed by medical therapy alone
7. immobilise joints inn severe arthritis

Question 7

complications

Answer 7

Carditis which involves the three layers of the heart:

1. bread and butter pericarditis, which may cause a friction rub, invariably resolving with few sequelae
2. myocarditis - may cause heart failure. Dilatation may result in mitral valvular incompetence especially
3. endocarditis and valvulitis - chronic rheumatic heart disease ensues in 50% of those with RF and carditis. Valvular damage is common, especially stenosis.

Question 8

prognosis

Answer 8

Chronic rheumatic heart disease develops in about 50% of patients with carditis. It is more likely:

• when the initial attack occurs in childhood
• when the initial attack of rheumatic fever was severe
• with recurrent attacks

Mitral stenosis is the most common outcome, followed by aortic stenosis. The tricuspid and pulmonary valves are rarely affected. Untreated, chronic valvular deformity usually results in eventual cardiac failure.

Recurrence of rheumatic fever may be precipitated by future streptococcal infection. Chorea may return with use of the contraceptive pill or pregnancy.

Question 9

2ry prophylaxis

Answer 9

Secondary prevention is required because subsequent streptococcal infection may precipitate recurrences of rheumatic fever.

Prophylaxis is effective as the bacterium does not become resistant to penicillin. Possible prophylactic measures include:

• oral penicillin 125 mg b.d.
• oral sulphonamide eg. sulphadimidine 0.5 g b.d.
• monthly administration of benzathine penicillin G
• for patients who are allergic to penicillin then erythromycin 250 mg b.d. can be used

Prophylaxis is given for at least 5 years. The duration of prophylaxis is dependent on whether there was carditis in the initial attack.

If there was no carditis in the initial attack then prophylaxis should be continued for 5 years - most recurrences occur within the first 5 years after the initial attack.

If a patient did suffer cardiac involvement with the initial attack then they should continue prophylaxis until the age of 25 years. Prophylaxis may be continued past this age if environmental conditions allow.

After 5 years or age 25 patients should have antibiotics for dental and other operative procedures for life.