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Idiopathic myocarditis characterized by marked right ventricular dilatation. Report of two autopsy cases
Insights
Chronic idiopathic myocarditis can cause severe right ventricular dilatation and heart failure in children. This rare condition requires careful differentiation from congenital heart diseases.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Pathology
Background:
- Idiopathic myocarditis is an inflammation of the heart muscle of unknown cause.
- Right ventricular dilatation can be a sign of severe heart dysfunction.
Observation:
- Two pediatric cases of chronic idiopathic myocarditis presented with significant right ventricular dilatation.
- Clinical findings included gallop rhythm, intraventricular block, and low voltage QRS complexes.
- Echocardiography and ventriculography revealed severe right ventricular dilatation, decreased contractility, and tricuspid regurgitation.
Findings:
- Histological examination confirmed chronic myocarditis and right ventricular dilatation.
- The right ventricular dilatation was disproportionately severe, exceeding left ventricular changes.
- Tricuspid regurgitation was a notable accompanying feature.
Implications:
- This presentation of idiopathic myocarditis is rare and poses diagnostic challenges.
- It highlights the potential for myocarditis to cause profound right heart failure.
- Distinguishing this condition from congenital heart diseases with similar presentations is crucial for appropriate management.
Abstract:
We encountered two children with chronic idiopathic myocarditis accompanied by marked right ventricular dilatation, who died of progressive right heart failure. A definitive diagnosis was made by histological examination of the myocardium at autopsy. The patients were both boys, aged 7 years and 1 year and 4 months, and a number of identical features were evident upon physical and laboratory examinations. No heart murmur was heard, and gallop rhythm was noted in distant heart sounds. Electrocardiogram revealed intraventricular block, low voltage QRS complex, and ST-T abnormality. Two-dimensional Doppler echocardiogram and right ventriculogram showed marked dilatation and decreased contractility of the right ventricle as well as tricuspid regurgitation. Thinning of the wall and marked dilatation of the right ventricle were confirmed at autopsy. Our observations showed that chronic myocarditis associated with tricuspid regurgitation may readily lead to marked right ventricular dilatation even exceeding the degree of left ventricular dilatation. Idiopathic myocarditis associated with such unusual features is relatively rare, and may present problems in differentiation from other congenital heart diseases causing dilatation and dysfunction of the right ventricle.