Fig. 2. Case showing the use of a Simmons-shaped guide catheter as an inner catheter. (A) Left ruptured posterior communicating artery aneurysm; (B) type III aortic arch; (C) navigation of the diagnostic catheter (arrow); (D) diagnostic catheter herniation into the aortic arch (arrow); (E) use of a Simmons-shaped guide catheter (double arrowhead) as an inner catheter, housed within a non-Simmons-shaped guide catheter (arrowhead) as the main guide catheter; (F) advancement of the main guide catheter to the cervical portion of the left internal carotid artery (arrowhead), facilitated by the Simmons-shaped guide catheter; and (G) post-coil embolization.