Once the morphology of the aortic arch is determined (Fig. 15-2), catheters are chosen for selective angiography of the cervical arteries supplying the brain (right and left carotid and vertebral arteries) and the cerebral vasculature. In a type I arch, Berenstein or Judkins right (JR) catheters are often used. In type II or III arch morphologies, shepherd’s crook–shaped catheters (i.e., Simmons or Vitek catheters) may be best (Fig. 15-3).

Figure 15-2 Aortic arch morphologies. Arch morphology is defined based on the origin of the great vessels. A, Type I arch: all vessels originate at the superior margin of the arch. B, Type II arch: at least one vessel originates between the superior and inferior margins of the aortic arch. C, Type III arch: at least one vessel originates below the inferior margin of the aortic arch.

Figure 15-3 Catheters for accessing the carotid artery. Berenstein or JR4 catheters are usually best for a type I arch. Shepherd’s crook catheters may be best for type II or type III arches.

Angiograms are obtained to delineate the anterior and posterior circulation supplying the brain. The intracranial and extracranial portions of each vessel are studied. Generally, two views of each are obtained, one in the anteroposterior projection and one in the lateral projection. Alternatively, some operators use rotational angiography. It is important to demonstrate the circle of Willis to define any baseline abnormalities. DSA may be performed with a 50/50 mix of saline and contrast. An external reference object is used with carotid angiograms in order to accurately measure the diameter of the artery.

Internal Carotid Intervention

A diagnostic catheter is used to engage the common carotid artery (CCA), and a roadmap angiogram is made of the carotid bifurcation. A 0.035-inch stiff-angled hydrophilic wire is advanced into the external carotid artery, and the diagnostic catheter is advanced over the wire. The hydrophilic wire is exchanged for a 0.035-inch stiff Amplatz wire over which an 8F guiding catheter or a 6F sheath may be advanced to the target vessel CCA. Care must be taken to avoid plaque disruption with wires and catheters, and at this point in the procedure, the plaque in the ICA should remain untouched.

For procedures performed with a filter-type distal embolic protection device (EPD), the target lesion is crossed with the EPD. Although there are no randomized trials comparing stenting with EPDs to stenting alone, one study found that 57% of EPDs contained debris upon retrieval. EPDs are standard of care in the United States, and several types exist (Fig. 15-4). If the distal EPD will not cross the lesion, the stenosis may be crossed with a conventional 0.014-inch guidewire and subsequently predilated with a small (2.5 mm) balloon. Then the EPD should be placed. After distal EPD deployment, the lesion is often predilated with an undersized coronary balloon, typically 3 to 4 mm in diameter. A self-expanding stent is then placed across the lesion. The stent is sized to fit the CCA, and as a general rule, self-expanding stents are typically sized at least 1 mm larger than the reference diameter. There is no demonstrated benefit for using tapered stents. It is common practice, when treating an internal carotid bifurcation lesion, to place the stent across the ostium of the external carotid artery (Fig. 15-5).