General Description

Radial artery access has long been the preferred route for cardiac interventions because of ease of access as well as the low morbidity and mortality rates associated with this approach. Neurointerventionists are increasingly learning the techniques associated with radial artery access and converting to this route for the full spectrum of neurointerventional procedures. Avoiding difficult arch and groin anatomy, simplifying access to the posterior circulation, and increased patient mobility and satisfaction are among the significant benefits.

Indications

Radial artery access is indicated for all neurointerventional procedures. The wrist can easily be used for procedures requiring a 6 French (F) access sheath and a sheathless 0.088-inch guide catheter can be inserted in most radial arteries for interventions requiring more robust access. Typically, staff will perform an Allen’s test to assess the patency of the palmar arch, but studies in the cardiac literature document low complication rates, even in the face of a negative (abnormal) Allen’s test.

Neuroendovascular Anatomy

The radial artery is the main artery of the lateral aspect of the forearm. It is a continuation of the brachial artery after it bifurcates into the radial and ulnar arteries in the cubital fossa. In most people, the radial and ulnar arteries form the superficial palmar arch, which serves as an anastomotic supply to the hand. The Allen’s test is used to verify the patency of this arch by first compressing both ulnar and radial arteries and then documenting blood flow to the distal hand with the release of each artery.

Specific Technique and Key Steps

A complete examination of the vascularity of the upper extremity should be performed, including palpating the radial and ulnar arteries, as well as checking for capillary refill in the ipsilateral hand. Many interventionists perform an Allen’s test to verify redundant supply to the hand. For ergonomic reasons, the right radial artery is commonly chosen for access ( Fig. 4.1 and Video 4.1 ); however, the left radial artery may be preferable, particularly when selecting the left vertebral or subclavian artery for subsequent intervention. In left vertebral or subclavian artery procedures, often the left arm is simply draped across the patient’s abdomen to allow the interventionist to proceed from the usual position at the right of the patient.

1. 
   

   After the wrist is prepared and draped, the radial artery is identified using a combination of palpation and ultrasound examination.

   
   
2. 
   

   Once the puncture site has been identified, a local anesthetic is administered through a 30-gauge needle and a wheal is raised over the intended puncture site.

   
   
3. 
   

   Using either single- or double-wall arterial puncture technique, a short sonographically guided opaque microneedle (i.e., 21-gauge micropuncture kit) is advanced at a 45° angle with the bevel facing up.

   
   
4. 
   

   Once the return of brisk, pulsatile, bright red blood is established through the micropuncture needle, a microwire is advanced through the needle into the radial artery. If resistance is noted, the practitioner should stop and redirect the wire. Once the wire has been advanced several centimeters, fluoroscopy is used to confirm location. The needle is then removed, and a 5F or 6F slender sheath is inserted ( Video 4.1 ).

   
   
5. 
   

   Once arterial access has been established, we infuse an anticoagulant/spasmolytic radial cocktail consisting of 2,000 units of heparin and 10 mg of verapamil.

   
   
6. 
   

   We routinely perform a radial artery angiographic run before proceeding with the case to assess the radial and brachial arteries for patency, stenosis, dissection, and possible extravasation ( Video 4.1 ).

   
   
7. 
   

   If larger gauge access is required, we measure the vessel on ultrasonography or angiography. A 3-mm vessel can easily support a 0.088-inch guide catheter. An exchange wire is advanced into the arch, and the guide sheath is removed. A sheathless guide catheter is advanced over an introducer into the radial artery.