The spectrum of double-outlet right atrium including hearts with three atrioventricular valves.

Double-outlet right atrium (DORA) is characterized by simultaneous right atrial emptying into both ventricles. Ventriculoatrial septal malalignment is the cardinal morphological feature. Three cases are presented to depict two major types of DORA-DORA with a malaligned atrial septum and DORA with a malaligned ventricular septum. We describe two subtypes of each form of DORA: DORA with a malaligned atrial septum presents with either a common atrioventricular (AV) junction (guarded by a common AV valve) or with a single AV junction (due to the absence of the left AV junction). DORA with a malaligned ventricular septum may be associated with a right ventricle (RV) that is adequate for biventricular repair or a severely hypoplastic RV not compatible with biventricular repair. DORA with a malaligned ventricular septum is closely related to typical straddling of the tricuspid valve. Peculiarly, DORA with a malaligned ventricular septum presents three AV valves at the AV junction and is associated with an abnormal disposition of the AV conduction axis. Clear understanding of the morphology of these lesions is important in preventing a surgical misadventure at the crux of the heart.