Myocarditis and pericarditis

The idea that organises the whole topic is that myocarditis and pericarditis are acquired inflammatory diseases, not structural congenital defects, and their danger lies in how fast a stable child can deteriorate. A school-age child with a viral prodrome and new chest pain can look well and then develop fulminant heart failure or tamponade within hours, so the bedside job is to risk-stratify aggressively rather than to reassure on the basis of a normal examination. ^{[2] [3]}

This page covers the recognition and resuscitation of both conditions, the diagnostic pathway of troponin, electrocardiogram and echocardiogram with cardiac magnetic resonance confirmation, the selective use of immunomodulation for myocarditis, the anti-inflammatory regimen for pericarditis, and the newer phenotypes of multisystem inflammatory syndrome in children and mRNA vaccine myocarditis that now dominate the differential in the adolescent. It links to the dilated cardiomyopathy and heart failure leaves for the chronic consequences and to the chest pain leaf for the broader differential. ^{[1] [9]}

Overview & Definition

Myocarditis is an inflammatory disease of the myocardium confirmed by clinical, imaging or histological criteria. The heart muscle is infiltrated by inflammatory cells, which injure myocytes through direct viral damage and through the host immune response, producing systolic and diastolic dysfunction and a propensity to arrhythmia. The American Heart Association scientific statement frames it as a clinically suspected syndrome supported by a raised troponin, electrocardiographic changes, imaging abnormalities or biopsy evidence. ^{[1] [3]}

Pericarditis is inflammation of the pericardial sac, usually producing a sharp, pleuritic chest pain that eases on sitting forward and worsens on lying back, often with a pericardial friction rub and diffuse electrocardiographic ST elevation. The danger is not the inflammation itself but the pericardial effusion it generates: when fluid accumulates faster than the pericardium can stretch, the heart is compressed and cardiac tamponade follows. The two diseases overlap often, because the visceral pericardium is the epicardium, giving the combined entity myopericarditis. ^{[2] [12]}

What makes these conditions hard is that the presentation is nonspecific, especially in infants and young children who cannot describe chest pain. A toddler may simply be tachypnoeic, irritable and off feeds, and the cardiac cause is missed because the clinician attributes the picture to a viral respiratory illness. The discipline that saves these children is to add a troponin and an electrocardiogram to the work-up of any child with unexplained tachypnoea, tachycardia or poor perfusion after a viral illness, and to examine for the friction rub and the signs of tamponade in any child with chest pain. ^{[1] [2]}

References15ShowHide

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