Anomalous right ventricular muscle bundles causing significant obstruction to right ventricular outflow constitute a relatively rare congenital abnormality and have been recognized as a clinical entity only since 1962.1,2 In a recent review, Forster and Humphries3 collected 42 cases from the literature and added 19 cases of their own. The condition most frequently occurs in association with a ventricular septal defect but has been reported in coexistence with various cardiac malformations,4 and rarely as an isolated entity.5
Subacute bacterial endocarditis has been reported in a single case, from Forster and Humphries's series. The present report is concerned with two additional cases, one in a child and another in a young adult, of severe right ventricular obstruction due to anomalous muscle bundles. Both had associated ventricular septal defect, and both developed subacute bacterial endocarditis as their presenting symptom.
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