Angiocardiography of subaortic obstruction in infancy

There is considerable heterogeneity among pathologic mechanisms responsible for subaortic obstruction in infancy. Although the relatively discrete forms of subaortic stenosis are uncommon in this age group, conoventricular malalignment, maladherent mitral valve, accessory endocardial cushion tissue, restrictive bulboventricular foramen, and a poorly expanded suboartic conus are responsible for most types of subaortic stenosis in this age group. The angiocardiographic recognition of these types of subaortic obstruction is aided by awareness of the anatomic framework in which they are found. For example: (1) conoventricular malalignment is commonly noted in patients with complete interruption of the aortic arch; (2) restriction at bulboventricular foramen level results in functional subaortic stenosis in those patients whose transposed aorta originates above an infundibular chamber; and (3) a poorly expanded subaortic conus may result in subaortic stenosis in patients whose ventricular loop and conotruncus have twisted in opposite directions (the anatomically corrected malposition). Subaortic obstruction in infancy is not uncommon, occurring in 99 of 1,362 necropsied infants with congenital heart disease. Nearly 70% of the patients with subaortic stenosis had obstructive anomalies of the aortic arch. Subaortic obstruction can be demonstrated angiographically, but high quality angiocardiographic technique is a prerequisite.