Treatment of Recurrent Stenosis After Previous Carotid Endarterectomy

Carotid endarterectomy (CEA) is the gold standard in the treatment of carotid occlusive disease and prevention of stroke. However, the benefit of carotid revascularization is hampered by restenosis, which is associated with a modestly increased risk for stroke. Symptomatic recurrent stenosis has been reported to range between 0.6% and 3.6%, and asymptomatic restenosis, based on noninvasive studies, ranges from 8.8% to 19%. A systematic review in 1998 concluded that the risk of developing restenosis after CEA was 10% in the first year, 3% in the second year, and only 1% per year thereafter. The potential of a carotid restenosis to cause a stroke seems to be highly variable, but in general it is smaller than that of the primary lesion. The optimal treatment strategy for recurrent stenosis, especially when asymptomatic, remains a challenge.

Symptomatic patients with a recurrent stenosis greater than 70% or asymptomatic patients with a recurrent stenosis greater than 80% may be considered for reintervention. The site of recurrent stenosis is primarily situated at the ends of or within the confines of the original endarterectomy site and the suture lines. The recurrence lesion therefore is located in the internal carotid artery (ICA), the distal common carotid artery (CCA), or both. The majority (70%) of lesions are localized within the origin of the ICA. Some regions of the artery wall are exposed simultaneously to low wall shear stress and high mechanical stress, and these regions correspond to the areas where atherosclerotic lesions develop. It makes the carotid bulb a focus for disease because of its geometry coupled with pulsatile flow that produces low shear rates, which in turn promotes atherosclerosis.

Optimal Imaging for Assessment of Carotid Restenosis

In the distant past, conventional angiography was required to determine the degree of a carotid stenosis. However, an accurate alternative with no need to use intra arterial contrast agents was found in duplex ultrasonography. The severity of a stenosis has been deﬁned using speciﬁc threshold velocities, including the peak systolic velocity (PSV), the end diastolic velocity (EDV), and/or the ICA/CCA PSV ratio. Most vascular laboratories use the (modified) Strandness criteria to grade restenosis after CEA. However, these criteria, established for evaluating primary carotid stenosis, might not be applicable in grading recurrent stenosis because of hemodynamic changes in the treated vessel.

Closing the arteriotomy with a patch widens the carotid diameter and decreases the stiffness of the arterial wall. This phenomenon is known as the dilatation or pantaloon effect following CEA. Hirschl and colleagues conducted a study to determine if patch angioplasty or direct closure of the ICA after CEA resulted in any hemodynamic or pathologic differences. Patients undergoing carotid patching with broadened bulb lumen exhibited statistically elevated turbulent flow disturbances with increased flow velocity in the ICA just distal to the patch. However, quantitative flow volume measurement did not reveal any differences between the two groups. Several papers have proposed new and revised ultrasound criteria, but there is still no consensus on the optimal criteria for grading recurrent carotid artery stenosis. It is therefore helpful to combine ultrasonography with an additional diagnostic modality, such as magnetic resonance imaging (MRI) or computed tomography (CT), to accurately evaluate the degree of stenosis.

Treatment Options for Recurrent Carotid Artery Stenosis

Whether recurrent carotid stenosis must be treated or not remains arbitrary. However, most authors agree that symptomatic restenoses warrant repeated intervention because of the risk of subsequent cerebrovascular events. Unfortunately, there are no reliable prognostic tests to differentiate between which highly stenotic lesions will cause a stroke and which will not. Most institutions therefore follow the consensus that reintervention should be considered in symptomatic patients with a recurrent stenosis of more than 70%, asymptomatic patients with a recurrent stenosis of more than 80%, patients with severe four-vessel disease, or patients with a contralateral occlusion. A second open procedure or endovascular intervention requires that the proposed treatment has a low periprocedural risk and provides long-term freedom from further cerebrovascular events.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here