General Description

A diagnostic cerebral angiogram, or any neuroendovascular intervention, starts with proper navigation of the aortic arch and craniocervical vessels. Recognition of the normal and variant anatomy is essential. Diagnostic cerebral angiograms provide information on vessel abnormalities, perfusion, and compensatory states. They provide the foundation for interventional neuroendovascular techniques, intra-arterial injection of chemotherapeutic, vasospastic, and other therapeutic agents, and Wada testing.

Indications

Diagnostic cerebral angiography is indicated for patients with intracranial and extracranial cerebrovascular disorders. These include carotid and vertebral artery (VA) diseases, stroke related to large vessel occlusion, vasculitis, intracranial aneurysms, arteriovenous malformations and fistulas, hypervascular extra- and intracranial tumors, severe epistaxis, and other conditions. (Venous angiography will be covered in a separate chapter.)

Aortic Arch Anatomy

The femoral artery is preferable for vascular access; however, radial and brachial access are also options (see radial and brachial access chapter for indications and details). The diagnostic catheter is advanced over a wire into the aortic arch. The abdominal and thoracic segments of the aorta have several branches, including the lumbar, renal, suprarenal, and intercostal arteries. Neurointerventionists must be aware of all of these branches to avoid inadvertent catheterization, accidental dissection, or rupture of these vessels. The aortic arch is the origin of three principal branches. From left to right, they are the left subclavian artery, the left common carotid artery (CCA), and the brachiocephalic trunk (i.e., innominate artery). Normal arch anatomy is found in 60%–70% of patients. The most common anatomical variations are the bovine arch, the left VA originating directly from the arch, and an aberrant right subclavian artery.

As people age, the aortic arch becomes elongated, dilated, calcified, and less compliant. The origin of the great vessels is less straightforward and arises at more proximal levels. The classification scheme for aortic arch elongation (types 1–4) correlates with increased difficulty in great vessel cannulation and increased risk of complications. A bovine arch is the most common variation. In this variation, the left CCA and the brachiocephalic (innominate) artery share a common origin (“true bovine”), or most commonly, the left CCA arises from the innominate artery itself.

Specific Technique and Key Steps

The neurointerventionist should understand the complexities of navigating the aortic arch anatomy ( Fig. 6.1–6.3 and Video 6.1–6.3 ). Noninvasive studies of the aortic arch, such as computed tomography angiography (CTA) or magnetic resonance angiography, should be obtained prior to any neurointervention if possible. These studies will aid in understanding the aortic arch and great vessel anatomy. The results may provide pertinent information about anatomical variations and ostial atherosclerotic disease.

1. 
   

   After the femoral angiogram has been performed to confirm the absence of any irregularity or dissection, fluoroscopy is used to guide the diagnostic catheter over a curved wire (0.035-inch angled Glidewire, Terumo) and into the aorta. It is important that adequate amounts of wire are extended beyond the catheter. If not, the wire becomes inflexible and may perforate vessels ( Video 6.1–6.3 ).

   
   
2. 
   

   For younger patients with straightforward anatomy, simple-curve catheters are a good option ( Fig. 6.1, 6.3 and Video 6.1, 6.3 ). The Glidewire is advanced over the aortic arch and into the ascending aorta and is followed with the angled catheter. The catheter tip is torqued until it is in a vertical upright position. When the catheter is in proper position, there is a gentle backward withdrawal of the catheter until it “clicks” into the ostia of the great vessels. The wire is advanced into the great vessel (innominate artery, left common carotid artery, or left subclavian artery) and then the catheter is advanced over the wire. The same maneuver is repeated for the rest of the great vessels. Contrast material can be kept to a minimum by carefully observing the “click” while withdrawing the catheter, instead of “puffing” (a gentle and quick injection of 0.5–1 cc of contrast). A glide catheter (Glidecath, Terumo) can be advanced with a “puff”/push technique or over a wire. Roadmap-guided advancement of the catheter beyond the carotid bulb is preferred for most patients; however, purely anatomically guided advancement of the wire is also possible.

   
   
3. 
   

   For older patients or patients with more complex anatomy, complex-curve catheters (e.g., Simmons 2 or 3, Terumo) are useful ( Fig. 6.2 and Video 6.2 ). The distal curve of a complex catheter needs to be reformed (i.e., reconstituted) before catheterizing the great vessels. When this is achieved, the catheter is pushed until the aortic arch is crossed. To select the innominate artery, the catheter is gently pulled while contrast material is injected to reveal the ostia of the innominate artery. When the catheter is in the ostia of the vessel, a more robust pullback will allow the catheter to advance distally into the great vessel, breaking the curve of the Simmons catheter so it operates like a traditional straight catheter. To advance the catheter further, a roadmap should be obtained. Then, the Glidewire is advanced into the vessel followed by the catheter. This maneuver is repeated for the rest of the great vessels ( Video 6.2 ). The removal of a Simmons catheter from a vessel should be performed similarly to its placement. Allow the catheter to herniate back into the arch and push it forward. Direct pulling on the catheter will require another reconstitution.

   
   
4. 
   

   The reconstitution or reformation of the Simmons catheter is achieved in the following manner ( Video 6.2 ). First, place the catheter into the arch over a wire and remove the wire past the curve. This is followed by a counterclockwise turn of the catheter to form an Omega sign. Next, apply gentle negative traction to place the Omega-shaped catheter under tension and move it to the least dilated area of the arch. Use firm, swift wire advancement to flip the catheter into its formed position. Finally, withdraw the wire and double flush the catheter. The Simmons can also be formed by “bouncing off” the aortic valve and via herniating out of the subclavian artery.

   
   
5. 
   

   Catheterization of the bovine origin of the left CCA with a complex-curve catheter will require the “scissors maneuver” or “figure 8” maneuver. While the catheter tip is at the brachiocephalic artery, the catheter is torqued until it forms a figure 8. This will orient the catheter tip medially toward the origin of the left CCA. Then, gentle advancement of the catheter will retract the tip of the catheter to fall into the ostium of the left CCA. When the catheter tip is engaged, the catheter is pulled back and turned in the opposite direction to unfold the figure 8 loop and secure its position.

Device Selection

1. 
   

   The diagnostic catheter type is preselected based on the patient’s age. A single-curve angled catheter is used for patients under 50 years, and a complex-curve angled catheter is used for patients over 50 years.

   
   
2. 
   

   Single-curve angled catheter:

   
   
   
   
   1. 
      

      Angle, Glide (Terumo), Standard or Beacon tip (Cook).

      
      
   2. 
      

      (used with 0.035-inch angled Glidewire).

      
      
   3. 
      

      Continuous heparinized flush.

   
   
3. 
   

   Complex-curve angled catheter:

   
   
   
   
   1. 
      

      Simmons-2 catheter (Terumo).

      
      
   2. 
      

      (used with 0.035-inch angled Glidewire).

      
      
   3. 
      

      Continuous heparinized flush.