图示主动脉肺动脉错位。它在动脉干隔膜非螺旋而是呈直线下降时发生。结果导致右心室的血流进入主动脉而左心室的血流则进入肺动脉。为了维持整个循环系统的正常运行，在休循环和肺循环之间一定存在联系。有时通过室间隔缺损或房间隔缺损相通。在左图，则通过未闭的动脉导管相通。
In the diagram above, transposition of the great vessels is shown. This occurs when the trunco-conal septum does not spiral down. Instead, it descends straight down. As a result, the outflow of right ventricle is into the aorta and the outflow from the left ventricle is into the pulmonic trunk.In order for this system to work, there must be a connection between the system and pulmonic circulations. Sometimes this is through a ventricular septal defect or an atrial septal defect. In the diagram at the left, this is through a patent ductus arteriosus.