Illusions, in a collected series of 10 cases, have led to the surgical closure of
the distal left pulmonary artery instead of the patent ductus. When the rare, anatomically
atypical patent ductus arises from the arch proximal to the subclavian artery, the
recurrent laryngeal nerve is found passing under the arch instead of under the ductus.
A large ductus creating the illusion of the arch, with the nerve beneath it, can lead
to the impression of an anatomically atypical ductus with the resultant surgical closure
of the distal left pulmonary in lieu of the ductus. For over two decades the problem
has been a recurring one which deserves recognition among the better known complications
of ductus operations.