Single ventricle physiology in keeping with a double inlet left ventricle and transposition of the great arteries (d-TGA) and associated Eisenmenger syndrome.

A case like this poses many diagnostic difficulties:

The smooth septal side of the single-chamber suggests the double inlet left ventricle, which gives rise to the dilated pulmonary artery and a connection to the small subaortic accessory chamber representing the hypoplastic right ventricle. The latter is positioned anteriorly (right) as opposed to posteriorly (left) suggesting a d-loop configuration.