Carotid Artery Stenting Diagnostic tools and interventional device recommendations, including how best to use distal embolic protection devices. By Edward Y. Woo, MD, and Ronald M. Fairman, MD ACCESS SITES Femoral artery Brachial artery if the infrarenal aorta is occluded; it is very difficult to get the wires and sheaths to track into the carotid via the brachial artery (most practical when approaching a left carotid lesion from the right arm via a bovine arch). Ipsilateral common carotid artery (CCA) if you are unable to access from the femoral or brachial artery (proximal CCA is usually easily exposed even in redo or radiated neck); if during carotid endarterectomy, the lesion is too high (can avoid mandibular subluxation). CONTRAST AGENTS Omnipaque (GE Healthcare, Waukesha, WI) Visipaque (GE Healthcare) A mixture of Visipaque and saline will reduce contrast doses without compromising visibility. TESTS/MONITORING Invasive monitoring (A-line) is not necessary. Telemetry and a blood pressure cuff are critical, especially at time of angioplasty. PHARMACEUTICALS Atropine Heparin Bivalirudin can be used as a substitute for heparin. Patients are pretreated with aspirin/clopidogrel for at least 1 week before and maintained on this regimen for 1 month after the procedure; extended-release dipyridamole can be used if clopidogrel is not tolerated. Patients with renal dysfunction can be pretreated with acetylcysteine solution and HCO3 solution. ANESTHESIA Local anesthesia with sedation is ideal (to allow the patient to move his/her head) and is also good for testing neurologic function. Oversedation may result in disinhibition and an uncooperative patient. DIAGNOSTIC DEVICES USED Sheath Sizes 6-F, 7-F Diagnostic Catheters 5-F long pigtail catheter can be used for arch angiograms; power injection. 5-F selective catheter can be used for selected carotid angiograms; hand injection. Note: all air must be removed to prevent air emboli. Selective Diagnostic Catheters JR4 (Cordis Corporation, Warren, NJ): angled catheter. H1 (Cordis): angled catheter with softer and longer tip. Vitek (Cook Medical, Bloomington, IN) or SIM1 (Cook Medical): reverse angled catheters; necessary for selecting orifices that originate at a reverse angle but they do not track well. Diagnostic Guidewires .035-inch Bentson wire (Cook Medical) Angled hydrophilic wire; if the wire needs to be steered, use a stiff angled hydrophilic wire; useful in tortuous vessels for tracking catheters. Diagnostic Notes Ensure that there is no air or debris in the injection tubing, catheter, syringe, etc. Thoracic aortograms are helpful for defining the arch (not necessary with a preoperative arch study [CTA/MRA]); however, there is a risk of stroke with each angiogram obtained. Left anterior oblique of 30° to 40° is helpful for splaying out the arch when selecting the artery. Be wary of a bovine arch or common origin when selecting the left CCA. Image intensifier position may need to be changed (oblique vs anteroposterior [AP]) to splay out the bifurcation and define the lesion. Intracranial views need to be in AP and lateral to fully define anatomy. Varying obliquities may be needed to splay out the carotid bifurcation. INTERVENTIONAL DEVICES USED Sheaths A 6-F or 7-F long sheath is used. It is optimal to have an 80-cm (becomes 90 cm with the Tuohy-Borst adapter [Cook Medical]) length so that a 100-cm catheter can form outside the sheath in case arterial selection needs to be performed through the long sheath. Wires A stiff wire allows introduction of the sheath into the carotid artery and may be needed as a buddy wire to support the sheath in extremely tortuous vessels. A device wire is a .014-inch wire that has the distal embolic protection (DEP) device on the end; the interventions are performed over this wire. A hydrophilic wire is used as a buddy wire for significant tortuosity and is helpful for introducing the DEP. PTA Balloons Monorail/rapid-exchange 4 to 8 mm in diameter, with various lengths (2 to 4 cm) Do not inflate the balloon outside the stent (dissection or spasm may result). Stents Usually, we use the stent associated with the DEP; however, sometimes we need to use a different one for trackability, visualization, etc. Stent should be self-expanding. Tapered stents are ideal because the stent will usually traverse from the internal carotid artery (ICA) to the CCA. The benefit of a closed-cell stent is unclear at this time, but it may be better. Neuroprotection DEPs must be prepared properly to remove any air. DEPs are usually deployed in the carotid siphon. DEPs may need to be sized for the ICA, depending on the manufacturer. DEPs at this point should be used in all carotid PTA/stenting procedures that are not part of clinical trials. Flow-reversal devices, currently in clinical trials, occlude the CCA and external carotid artery to allow flow reversal of the ICA; blood is returned to the venous system after filtration. INTERVENTIONAL NOTES Never lose the wire. Minimize arch manipulations because this is a significant source of emboli. The DEP, when open, cannot be pulled through the stent or it will get stuck; thus during manipulations, it is important to note the location of the DEP. Predilation is usually not necessary unless the stent will not cross the lesion. The interventionist should try to limit to one stent to minimize manipulations. Postdilation is usually necessary. Atropine should be made up and ready to inject if bradycardia or asystole occurs. Some patients may be good candidates for prophylactic atropine (.5 mg; bradycardic, octogenarians). Minimize manipulations around the lesion before the DEP is deployed. A good road map is necessary for manipulations. With each maneuver (DEP deployment, PTA, stenting), a new road map should be generated because the anatomy can become distorted or the patient can move. Severe calcification or tortuosity may be a contraindication to carotid artery stenting. Completion angiography should be performed before capturing the DEP; this keeps the wire in place in case another manipulation (ie, repeat PTA or additional stenting) is necessary. Completion angiogram with an abrupt cutoff at the DEP usually suggests an occluded DEP (debris, thrombus); immediate aspiration followed by capture of the DEP should be performed with repeat angiography. Spasm can be treated with intra-arterial nitroglycerine. Salvage procedures can be performed with microcatheters, abciximab, and thrombolytics. Edward Y. Woo, MD, is Assistant Professor, Division of Vascular Surgery, University of Pennsylvania Medical Center, in Philadelphia, Pennsylvania. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Woo may be reached at (215) 662-7836; wooe@uphs.upenn.edu. Ronald M. Fairman, MD, is Chief, Division of Vascular Surgery, University of Pennsylvania Medical Center, in Philadelphia, Pennsylvania. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Fairman may be reached at (215) 614-0243; ron.fairman@uphs.upenn.edu.