The frontal chest film as a method of suspecting transposition complexes.

The frontal chest film as a means of suspecting transposition complexes is discussed. The first step is recognizing the normal relationships formed by the ascending aorta, an aortic knob-descending aorta, and pulmonary trunk. The concept of which ventricle is connected to which atrium is developed--the terms ventricular noninversion and inversion being utilized. Frontal chest film signs of transposition are summarized as follows: 1) in the majority of transposition complexes, absence of the pulmonary trunk is the premier sign; 2) patients with ventricular noninversion tend to show the ascending aorta and aortic knob-descending aorta in normal position. Patients with ventricular inversion usually show absence of all three great artery relationships. 3) In ventricular inversion, the left heart border shows a septal notch or a diffuse convex bulge (two ventricles), or a discrete bulge high up on the left border (single ventricle).