AORTIC OUTFLOW OBSTRUCTION IN VISCERAL HETEROTAXY - A STUDY BASED ON 20 POSTMORTEM CASES

Aortic outflow tract obstruction can complicate the clinical course an d surgical management of patients with heterotaxy syndromes, but its a natomic basis has not been described in detail. In 20 postmortem cases with asplenia (n = 4) or polysplenia (n = 16), the anatomic causes of aortic outflow tract obstruction were absence of the subaortic conus in association with (1) narrowing of the subaortic outflow tract betwe en the conal septum anteriorly and the common atrioventricular (AV) va lve posteriorly in six (30%) patients; (2) aortic valvar atresia in fo ur (25%), three with asplenia and one with polysplenia; (3) redundant AV valve leaflets in four (20%); (4) excessive AV valve fibrous tissue in four (20%); (5) marked hypoplasia of the mitral valve and left ven tricle in two (10%); and (6) aneurysm of membranous septum in one (5%) . One patient belonged to group (1) and (4). Aortic outflow tract obst ruction was much more common with polysplenia (28%) than with asplenia (4%) (p < 0.001).