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.