Myocarditis and pericarditis — branching viva

Stage 1 — The acute myocarditis presentation

The examiner shows you a nine-year-old boy with central chest pain, breathlessness and palpitations a week after a viral illness. He has a gallop rhythm and a markedly raised troponin, with widespread electrocardiographic changes and a moderately impaired left ventricle on echocardiogram. [1]

• What is your working diagnosis, and what three bedside investigations anchor it? Troponin, electrocardiogram and echocardiogram anchor the diagnosis of acute myocarditis. [2]
• What non-invasive test confirms the tissue diagnosis in the stable child, and what criteria does it apply? Cardiac magnetic resonance applying the Lake Louise criteria of oedema, late gadolinium enhancement and hyperaemia. [4]
• What is the role of endomyocardial biopsy, and when is it indicated? Reserved for fulminant disease and suspected giant cell or eosinophilic myocarditis; it adds immunohistochemistry and viral genome detection. [5]

Stage 2 — The fulminant deterioration

Twelve hours later the boy is hypotensive, oliguric and cold, with a rising lactate and sustained ventricular tachycardia. The examiner asks for your management. [8]

• What complication has developed, and where must this child be managed? Fulminant myocarditis with cardiogenic shock; he belongs in a paediatric intensive care unit with cardiac and mechanical-circulatory-support capability. [3]
• What is the definitive intervention when inotropes fail, and what paradox about recovery should you state? Early venoarterial extracorporeal membrane oxygenation or a ventricular assist device; fulminant disease often recovers near-normal function once supported through the storm. [8]
• What is the role of intravenous immunoglobulin and corticosteroids in this child? Not routine; the Cochrane review finds no firm benefit for immunoglobulin in presumed viral myocarditis. [6]

Stage 3 — The adolescent with recurrent pericarditis

The examiner moves to the outpatient clinic. A fifteen-year-old girl has her third episode in eight months of sharp pleuritic chest pain eased by sitting forward, with a friction rub, diffuse ST elevation and a moderate pericardial effusion. [12]

• What is the diagnosis, and what bedside sign is pathognomonic? Acute pericarditis; the pericardial friction rub is the pathognomonic bedside sign. [2]
• Outline the medical regimen to treat the episode and prevent recurrence, including the drug class to avoid and why. A high-dose non-steroidal anti-inflammatory drug plus weight-based colchicine for at least three months; avoid corticosteroids in a first idiopathic episode because they raise the recurrence rate. [13] [14]
• If the episode progressed to hypotension with a raised jugular venous pressure and pulsus paradoxus, what would you do? Perform emergency echocardiography-guided pericardiocentesis for tamponade, not further imaging first. [15]