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September 1972

Anomalous Right Ventricular Muscle Bundles and Ventricular Septal Defect Complicated by Subacute Bacterial Endocarditis

Author Affiliations


From the departments of medicine and pediatrics, the University of Chicago Pritzker School of Medicine, Chicago.

Arch Intern Med. 1972;130(3):404-407. doi:10.1001/archinte.1972.03650030082019

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.

Patient Summaries 

Patient 1.  —This Negro boy was born in

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