Medical Mystery: Abnormal Chest Film — The Answer

To the Editor: The medical mystery in the July 27 issue1 involved a chest film (Figure 1A) showing cardiomegaly and a left-sided pacemaker, the leads from which took an unusual course through the mediastinum, to the left of the midline. A persistent left-sided superior vena cava was suspected. A right-sided paratracheal soft-tissue density was also present (Figure 1A, arrowheads). Contrast-enhanced computed tomography (CT) showed that this density was caused by a right-sided aortic arch and not by an aortic-arch aneurysm (Figure 1B, arrow). An aberrant left subclavian artery arising from a dilated diverticulum of Kommerell (Figure 1C, curved arrow) passed . . .