overriding aorta

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 [a-or´tah] (pl. aor´tae, aortas) (L.)
the great artery arising from the left ventricle, being the main trunk from which the systemic arterial system proceeds. It has four divisions: the ascending aorta, the aortic arch, the thoracic aorta, and the abdominal aorta. See Appendix of Arteries and see circulatory system.
 Aorta, arising from the left ventricle, ascending, arching, then descending through the thorax to the abdomen, where it divides into the common iliac arteries. From Dorland's, 2000.
overriding aorta a congenital anomaly occurring in tetralogy of Fallot, in which the aorta is displaced to the right so that it appears to arise from both ventricles and straddles the ventricular septal defect.

o·ver·rid·ing a·or·ta

a congenitally malpositioned aorta the origin of which straddles the ventricular septum and so receives ejected blood from the right ventricle as well as from the left; it is found especially in tetralogy of Fallot.
References in periodicals archive ?
TOF is characterized by a large ventricular septal defect (VSD), right ventricular hypertrophy, right ventricular outflow obstruction (RVOT) and an overriding aorta. The first successful repair of TOF was conducted in 1954 in a little boy by Lillehei and associates1.