persistent truncus arteriosus

[trŭngkəs är-tîr′ē-ōsəs]
n.
  1. A congenital cardiovascular deformity resulting from the failure of the septum between the aorta and pulmonary trunk to develop and characterized by a common arterial trunk opening out of both ventricles with the pulmonary arteries branching from the ascending common trunk.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.