Acute rheumatic fever and rheumatic heart disease — formative SAQs

SAQ 1 (10 marks) — The Aboriginal boy with a migratory arthritis and a new murmur

Stem: A nine-year-old Aboriginal boy from a remote Northern Territory community presents with a four-day history of a swollen, painful left knee that over two days moved to the right ankle and then the right elbow. He has a fever of 38.5 degrees Celsius. His mother recalls a sore throat about two weeks ago. On examination, there is a high-pitched apical pansystolic murmur radiating to the axilla. Outline your diagnosis, investigations, and management. [5] [3]

Model answer

Diagnosis and Jones criteria (2 marks). The most likely diagnosis is acute rheumatic fever. The major criteria are the migratory polyarthritis and the clinical carditis (the new apical pansystolic murmur of mitral regurgitation). The minor criteria are the fever and the history of arthralgia. In a high-risk population — Aboriginal children in the Northern Territory — the high-risk Jones criteria apply across all of Australia and New Zealand per the 2020 guideline, and monoarthritis or polyarthralgia may substitute for polyarthritis. Here the full polyarthritis and the carditis already meet two major criteria. [1] [3]

Investigations (3 marks). Confirm the streptococcal link with antistreptolysin O and anti-DNase B titres, which confirm recent group A streptococcal infection. Request echocardiography, which is the single most important investigation, because the 2015 revision allows subclinical carditis detected on Doppler echo alone to count as a major criterion. Measure the acute-phase reactants (erythrocyte sedimentation rate and C-reactive protein) as minor criteria. Perform an electrocardiogram for the prolonged PR interval. A chest radiograph assesses cardiomegaly and pulmonary congestion if carditis is suspected. [1] [5]

Management of the acute episode (3 marks). Aspirin at fifty to seventy-five milligrams per kilogram per day is the standard anti-inflammatory for the arthritis and mild carditis, and the dramatic response within twenty-four to forty-eight hours is itself a diagnostic clue. Bed rest is recommended during the active inflammatory phase. The heart failure, if present, is treated with diuretics. Eradicate the streptococcus with oral penicillin V or a single dose of intramuscular benzathine penicillin. [5] [3]

Secondary prophylaxis and disposition (2 marks). Commit the child to intramuscular benzathine penicillin G every twenty-one to twenty-eight days, at nine hundred milligrams (one point two million units) for a child of this weight. Per the 2020 Australian guideline, prophylaxis continues until at least age twenty-one for no established RHD, and longer if RHD is already present. Enter the child on the regional rheumatic heart disease register, counsel the family in their language, and arrange the structured primary care and community health partnership that sustains the prophylaxis. [3]