General Description

Although carotid artery stenosis can be successfully treated with either endarterectomy or stenting, certain patient populations have elevated risks for each procedure. Consequently, transcarotid artery revascularization (TCAR) was developed to apply surgical principles of embolic protection in patients for whom surgery is less desirable. Specifically, TCAR utilizes flow reversal by creating a temporary shunt between the carotid artery and the femoral vein, thus allowing for placement of a stent while minimizing embolic risk to the brain.

Indications

TCAR has the lowest documented 30-day stroke rate of any carotid revascularization intervention. Indications include both symptomatic and asymptomatic high-grade carotid artery stenosis. Because TCAR obviates accessing the arch, arch type, calcifications, and soft plaque that elevate risk for transfemoral or transradial stenting are less concerning. Furthermore, distal tortuosity in the carotid artery is better tolerated under TCAR because it is not necessary to deploy distal protection. Cases with carotid plaques that demonstrate circumferential calcification should be avoided.

Neuroendovascular Anatomy

The common carotid arteries (CCAs) typically arise from the brachiocephalic trunk (right and bovine left) or aortic arch (left). The carotid artery then passes obliquely under the sternoclavicular joint, deep to the distance between the two heads of the sternocleidomastoid, as it courses into the lateral neck. At the C3 vertebral level, the CCA usually bifurcates into the internal and external carotid arteries, which supply the brain and face, respectively. The distance between the clavicle and bifurcation is approximately 10 cm. This is the segment that will be accessed for TCAR. To create flow reversal, a TCAR shunt is created between the CCA and the femoral vein (details below). The left femoral vein is preferred for ergonomic reasons and is accessed just medial to the femoral artery in the femoral triangle.

Specific Technique and Key Steps

1. 
   

   Initial access of the target carotid artery begins with identification of the CCA 1 cm above the clavicle. A 2-cm horizontal incision is marked overlying the CCA.

   
   
2. 
   

   The skin is incised with a 10-blade, and skin hooks are utilized to retract the skin. Using a combination of blunt dissection with Metzenbaum scissors and electrocautery, the subcutaneous tissues and fat are carefully dissected to expose and circumferentially dissect a 2-cm length of the CCA, staying between the two heads of the sternocleidomastoid muscle. Ultrasound guidance and palpation of the pulse can guide the exposure ( Fig. 13.1, Video 13.1 ).

   
   
3. 
   

   A vessel loop is wrapped around the carotid artery twice and a Rumel tourniquet is loosely placed to establish proximal vascular control.

   
   
4. 
   

   A purse-string suture is placed into the exposed superior surface of the carotid artery using 6-0 prolene and Castroviejo needle drivers.

   
   
5. 
   

   Left femoral vein access is obtained as previously described in the femoral vein access chapter. The TCAR venous sheath is placed into the vein and secured with a silk suture.

   
   
6. 
   

   The TCAR arterial sheath is placed into the exposed carotid artery using a modified Seldinger technique. The central area, rimmed by the purse-string suture, is utilized to facilitate arteriotomy closure at the completion of the case. The sheath is secured to the skin with a silk suture.

   
   
7. 
   

   Placement of the sheath in the CCA is verified with fluoroscopy. Cervical and cranial angiographic runs are obtained to assess anatomy and aid in device selection ( Fig. 13.1, Video 13.1 ).

   
   
8. 
   

   Heparin is administered intravenously to the patient, and therapeutic activated coagulation time verification is established.

   
   
9. 
   

   The carotid stent should be selected based on the diameter of the CCA and with sufficient length for placement that starts within a straight segment of the internal carotid artery and extends securely into the CCA.

   
   
10. 
    

    The TCAR shunt apparatus is attached to the arterial sheath and allowed to fill with blood to flush out all air. Once the apparatus is completely flushed, it is connected to the venous shunt. Flow is activated, shunting blood from the carotid artery to the femoral vein. The vessel loop is tightened to occlude the proximal CCA and complete the flow reversal process ( Video 13.1 ).

    
    
11. 
    

    With flow reversed, the selected stent and wire are introduced through the arterial sheath. The wire is advanced through the stenotic lesion and into the horizontal petrous segment.

    
    
12. 
    

    The practitioner can proceed with presenting angioplasty of a high-grade lesion or stenting if no angioplasty is anticipated. Both procedures proceed as per standard protocols (see Chapter 10), and the devices are withdrawn. ( Video 13.1 )

    
    
13. 
    

    Post-stenting angiographic runs of both cervical and intracranial vasculature are obtained to verify stent placement and evaluate for thrombus.

    
    
14. 
    

    The wire is withdrawn after all stent manipulations have been completed.

    
    
15. 
    

    The shunt is turned off, and the apparatus is disconnected.

    
    
16. 
    

    The arterial sheath is withdrawn as the purse-string suture is tightened and tied to close the carotid arteriotomy.

    
    
17. 
    

    The tourniquet is released to reestablish anterograde flow.

    
    
18. 
    

    The neck wound is closed in layers using standard surgical technique.

    
    
19. 
    

    The venous access is removed and the vessel closed by applying manual pressure.