A family study of Fallot's tetralogy.

This analysis concerns Fallot's tetralogy, a form of cyanotic congenital heart disease about which there is little information relating to the population of north east England, and attempts to assess the influence of familial and other variables possibly concerned in its aetiology. This disease of the heart is named after Fallot who described it in 1888, though it had been recognized as a clinical entity over 200 years previously (Stensen, 1671). Classically, the condition includes 4 features: pulmonary obstruction, ventricular septal defect, right ventricular hypertrophy, and dextroposition of the aorta. Physiologically the combination of a ventricular septal defect with an obstruction of the pulmonary outflow tract results in a predominantly right to left shunt. The degree of overriding of the aorta varies individually, but it is the size of the ventricular septal defect together with the degree of pulmonary obstruction which determines the severity and clinical picture. The classification of congenital heart disease in childhood produced by the International Society of Cardiology (Watson, 1970) recognizes this by including the tetralogy in the category 'ventricular septal defect with obstruction of the right ventricular outflow tract'.