Cerebral angiography can usually be performed without the need for an aortic arch injection. Considering the time, effort, difficulty, and contrast load involved in a pigtail catheter injection in the ascending aorta, and then replacing that catheter with one suitable for selective angiography, the undertaking is usually not worthwhile on a routine basis (1). However, an arch aortogram may prove necessary in the setting of proximal great vessel stenosis, tortuosity, or anatomic variations. This can be accomplished with 30 to 50 mL of contrast. The best projection is usually 30 to 40 degrees in a left anterior oblique projection. It should be considered prospectively in patients in whom proximal stenotic disease is suspected, particularly with cases such as subclavian steal phenomenon, or in patients with congenital heart disease. Additionally, during catheterizations that are proving exceptionally difficult, resorting to an arch aortogram can clarify the anatomy immediately.

The many possible variations of the aortic arch can prove a challenge for catheterization (Fig. 8-1). The most common variations, a bovine arch (Fig. 8-1B and C), origin of the left vertebral artery from the arch (Fig. 8-1H), and an aberrant right subclavian artery (Fig. 8-1K), can be quickly recognized and catheterized without an arch injection.