HOLLYWOOD, FLA. — To make carotid artery stenting as safe as possible with the goal of zero procedure-related strokes, “patient selection is as or more important than technique,” Dr. Gary S. Roubin said at ISET 2008.
“To get zero strokes you must select patients with low-risk anatomy,” Dr. Roubin said at an international symposium on endovascular therapy. By following this rule, and by using the technical tips he described in his talk, his group has recently done carotid artery stenting with a 30-day rate of stroke or death of less than 3% in octogenarian patients, and less than 2% in lower-risk patients, said Dr. Roubin, chairman of the department of interventional cardiology at Lenox Hill Hospital in New York.
In his practice, patients with at least two of the following anatomic risk factors are treated with carotid endarterectomy instead of carotid-artery stenting: age of 80 or older; excessive carotid artery tortuosity; low cerebral blood-flow reserve; and heavy, concentric calcification in the carotid artery.
Excessive carotid artery tortuosity means a 90-degree bend in the internal carotid artery soon after it branches off of the common carotid artery that is followed by a second, 90-degree bend in the internal carotid artery that is within 5 cm of the first 90-degree bend. Concentric calcification in the carotid artery coupled with tortuosity poses a “nightmare” for stenting, he said.
“Disease in the common carotid and external carotid makes sheath access support more difficult. You cannot safely put a 0.035-inch or 0.038-inch-diameter support wire across this disease without risking embolization.”
Dr. Roubin detailed the technical and management steps he follows to minimize the risk of stroke or death in patients who are not exempted from carotid stenting by their anatomy, flow reserve, or age:
▸ Optimize antiplatelet therapy before carotid catheterization. Dr. Roubin recommended treating patients with either 325 mg aspirin and 75 mg clopidogrel (Plavix) daily starting at least 5 days before catheterization, or 650 mg aspirin and 600 mg clopidogrel 4 hours before catheterization. He also recommended treating patients with bivalirudin (Angiomax) and avoiding treatment with a glycoprotein IIb/IIIa antagonist.
▸ Aggressive management of patients' hemodynamics. Antihypertensive medications should not be administered the morning of the procedure. The patient should not be anesthetized or sedated, and should be well hydrated. A 1-mg dose of atropine should be routinely administered, and blood pressure should be monitored throughout the procedure. A bolus of phenylephrine (Neosynephrine) should be on hand in case of hypotension. If the patient becomes hypertensive during the procedure, treat with nitroglycerin or labetalol.
▸ Catheterize the carotid with great care. The 0.035–0.038-inch Amplatz wire, sheath, or sheath introducer should not touch the lesion. Once the sheath is in place, it's prudent to reassess the tortuosity of the carotid artery. For example, pushing on the bifurcation can create new tortuosity. Use of a buddy wire can trigger problems, such as a pseudospasm or flow interruption. To reduce tortuosity, try removing the patient's head restraint and placing the head flat on the table with the chin up and the neck stretched. Don't allow the sheath to prolapse back into the arch when advancing devices through the lesion.
▸ Minimize the time when an embolic protection filter is deployed. There is a direct correlation between prolonged deployment time and complications. To minimize deployment time, have all of the equipment ready and prepped on the table, including the pre- and postdilation balloons, the stent, and all drugs. Use a “soft” embolic protection device wire, and shape it into a broad curve before deployment to allow fast and easy access to the internal carotid artery. And don't underestimate the space needed within the carotid artery for the embolic protection device.
▸ Minimize the neural effects of contrast. Contrast is toxic to the brain, and microbubbles and emboli induced during stenting can cause neurologic events. Constantly check the syringe, manifold, and Y adapter for air and blood. And constantly back-bleed and clear after each device is introduced or removed. Do not attempt to inject contrast while positioning the stent.
▸ Postdilating the stent is the most dangerous step. Postdilate only once, using a conservative balloon size. Take angioplasty out of carotid angioplasty and stenting. A balloon diameter of 5 mm is right for most patients; rarely is a 5.5-mm balloon needed. And don't continue to inject contrast during this step. Deploy one stent, use one conservative postdilation, and then get out of the carotid. Never inflate the postdilation balloon more than once in the same place. And ignore the little issues. Trivial concerns that should not be addressed by additional treatments include spasm, residual ulceration, residual stenosis, kinks, an external carotid artery that is stenosed or occluded, and small tears.