We describe two infants having an atrioventricular septal defect in the setting of a double inlet atrioventricular connection, but with patency of the left-sided valvar orifice and an imperforate right-sided valvar component, and a further case with atrioventricular septal defect and an imperforate Ebstein's malformation, all producing the haemodynamic effect of tricuspid atresia. We make comparisons with the arrangement in trisomy 16 mice, in whom deficient atrioventricular septation is seen at times with the common atrioventricular junction exclusively connected to the left ventricle, a situation similar to that seen in two of our infants. We also review previous reports emphasising the important theoretical implication of the findings despite their rarity.

Previous studies have demonstrated the individual association of subpulmonary tissue tags, dissection of the pulmonary trunk and primitive neuroectodermal tumors with congenital heart disease. We are reporting a case of double inlet left ventricle with all these associations as it is exceptionally rare for all features to be manifest in one individual.

There is a clear and present danger for the patient considered for Fontan's operation in the presence of excessive ventricular hypertrophy and/or mass. Such ventricular hypertrophy and/or mass probably reflects singly, or in combination, banding of the pulmonary trunk and subaortic stenosis, as well as other factors. While one can construct a number of therapeutic algorithms for patients seen at various ages with a restrictive ventricular septal defect and subaortic stenosis in the setting of double inlet left ventricle and discordant ventriculoarterial connections, the optimal management should be to minimize the potential risks for development of subaortic stenosis and excessive ventricular hypertrophy and/or mass.

At first sight, the venous and arterial poles of the heart seem to belong to a single structure. This feature is demonstrated by the continuity seen in the fibrous skeleton between the leaflets of the aortic valve with those of both the mitral and tricuspid valves. Moreover, the orifice of the aortic valve is deeply wedged in between the fibrous annuluses supporting the two atrioventricular valves.