Carotid endarterectomy with adjunctive cephalad carotid stenting: Complementary, not competitive, techniques
Article Outline
Objective
Stenosis of the cephalad internal carotid artery (ICA) can present a challenge, making it difficult to obtain a technically satisfying distal end point during endarterectomy. Surgical revision of distal defects can be difficult and yield unsatisfactory results. The purpose of this review is to evaluate the efficacy of intraoperative carotid stenting as an adjunct to endarterectomy to salvage technical defects identified at the cephalad ICA endarterectomy site.
Methods
Between January 2001 and February 2008, 14 patients were found to have technical defects located at the cephalad ICA endarterectomy site on intraoperative completion arteriogram. All defects were treated with adjunctive carotid stenting. Patient age ranged from 53 to 84 years (mean, 69 years). Indications for surgery were asymptomatic stenosis (nine), amaurosis fugax (two), and cerebrovascular accident (three). Operative time ranged from 2 to 5 hours (mean, 2.5 hours). Cervical block was used in all but two patients who received general anesthesia.
Results
Technically satisfying results with stenting were achieved in all 14 patients. One patient suffered a perioperative transient ischemic attack; however, neurologic symptoms were noted before placement of the stent in this patient. There were no stent-related complications. All stents remained patent on duplex follow-up averaging 18 months.
Conclusion
Intraoperative salvage carotid stenting is an effective and safe adjunct to endarterectomy when unsatisfactory technical defects are identified at the cephalad ICA endarterectomy site.
Atherosclerotic disease of the internal carotid artery (ICA) is a principal cause of ischemic stroke. Carotid endarterectomy (CEA) has been shown to be effective at reducing stroke risk, and is warranted for moderate-to-severe symptomatic1 and severe asymptomatic2 narrowing of the ICA. More recently, carotid stenting has been advocated in preference to open endarterectomy in some patients. Recently, the Center for Medicare and Medicaid Services cited a lack of evidence to support the routine use of stenting over endarterectomy for asymptomatic patients. However, in selected symptomatic patients with moderate-to-severe ICA stenosis who are at risk for surgery, stenting may be preferred.3 Although this debate is not yet settled, we propose a circumstance in which these two treatment modalities need not be competitive but complementary.
During CEA, exposure of the cephalad ICA can occasionally present a challenge, making it difficult to obtain a technically satisfying distal end point. This can be the case with a high carotid bifurcation or an ICA lesion that extends more cephalad than suggested on preoperative studies. Additional challenges can be presented by poor distal tapering of endarterectomized plaque, stenosis from patch closure, intimal flaps, and distal suture line bleeding that requires repair sutures. Despite techniques such as full hypoglossal nerve mobilization, division of the digastric muscle, and maneuvers to minimize poor exposure due to the mandible,4 technical defects at the cephalad ICA endarterectomy site can result. Surgical revision of these distal defects can be difficult and yield unsatisfactory results.
In these circumstances, we have used adjunctive carotid stenting in preference to surgical revision and herein present our experience.
Methods
Patient demographics
Between January 2001 and February 2008, two vascular surgeons at our institution performed a total of 487 carotid endarterectomies: 462 primary procedures and 25 reoperations for recurrent stenosis. The overall hospital stroke and death rate was 1.4% (7 patients).
Fourteen patients were found to have technical defects at the cephalad ICA endarterectomy site. The defects were found by intraoperative completion arteriogram, which we perform routinely, and included stenosis (n = 10) and intimal flaps (n = 4).
Patient age ranged from 53 to 84 years (mean, 69 years). There were seven males and seven females. The demographic distribution among these patients was typical for atherosclerotic disease, with hypertension in 13, diabetes mellitus in 4, hyperlipidemia in 11, and tobacco use in 10. Additional comorbidities included coronary artery disease in five, end-stage renal disease in two, chronic obstructive pulmonary disease in one, and previous ipsilateral carotid endarterectomy in two.
The indication for surgery was cerebrovascular accident in three, amaurosis fugax in two, and asymptomatic severe stenosis in nine. Preoperative evaluation of carotid disease in nine patients was based on duplex scans performed in our accredited noninvasive vascular laboratory, which has been our protocol for more than 10 years.4 Remaining patients also had magnetic resonance angiography (two), computed tomography angiography (two), and contrast arteriogram (one).
Operative technique for endarterectomy
Cervical block anesthesia was used in 12 patients, whereas two had general anesthesia. Cervical block was used in 90% of patients who underwent CEA at our institution and is preferred unless contraindicated. Although the decision to shunt was guided by neurologic status in awake patients, carotid stump pressure measurements were also performed on all patients. In anesthetized patients with a systolic stump pressure of less than 50 mm Hg, a shunt was placed.5 Shunting was required in three of the 14 patients: two for stump pressures less than 40 mm Hg and one for the development of neurologic deficit (loss of consciousness) with clamping. Endarterectomy was performed with Dacron patch closure in 12 patients, anterior jugular vein patch closure in 1, and eversion endarterectomy in 1. Intraoperative completion arteriogram, which we perform routinely, identified unacceptable technical defects at the cephalad ICA endarterectomy site in these 14 patients. The defects identified included residual stenosis, intimal flaps, and severe kinking. Figs 1a and 2a demonstrate such lesions.
Fig 1.
Distal internal carotid artery stenosis after carotid endarterectomy and before adjunctive stenting (a), and after adjunctive stenting (b).
Fig 2.
Distal intimal flap of the internal carotid artery after carotid endarterectomy and before adjunctive stenting (a), and after adjunctive stenting (b).
Operative technique for stenting
When an unacceptable distal ICA endarterectomy site defect was identified and stenting was elected, additional intravenous heparin was given to maintain an activated clotting time greater than 250 seconds. The external carotid artery and common carotid artery (CCA) were then clamped to prevent cephalad flow, thus minimizing the risk of embolic stroke. In the patients who required shunting, clamping was used only during sheath placement and stent deployment, whereas in the remaining patients flow was interrupted for the entire procedure. Using the Seldinger technique and under direct vision, the surgeon placed a 6F pinnacle sheath through the skin inferior to the incision and into the CCA just superior to the clamp occluding it. Care was taken not to enter the ICA with a wire during sheath placement. A contrast arteriogram with road mapping was then performed to facilitate stent placement. Next, a short 0.035 hydrophilic wire was advanced across the defect into the ICA, keeping the tip below the siphon. The diameter of the ICA was then measured and a self-expanding stent (Wallstent; Boston Scientific, Natick, Mass) was primarily deployed in all patients. No patient required balloon angioplasty. In most patients the stent did not extend into the CCA. Embolic protection devices were not used, but the sheath was vigorously aspirated before re-establishment of antegrade flow. All patients were given a loading dose (300 mg) of Plavix in the recovery room followed by a maintenance dose of 75 mg daily for 6 weeks.
Results
Technically satisfying results were obtained with adjunctive stenting in all 14 patients. Fig 1, Fig 2 show arteriograms before and after stenting. Operative time ranged from 2 to 5 hours with an average time of 2.5 hours. This time compares with a mean time of 1.5 hours for endarterectomy alone at our institution. There were no stent-related complications. One patient experienced intraoperative worsening of a pre-existing neurologic deficit (contralateral arm weakness). This finding, however, had developed before stenting and resolved within hours of onset. All stents remain widely patent on duplex scanning, and no patients have experienced significant recurrent stenosis at mean follow-up averaging 18 months.
Discussion
Carotid endarterectomy is one of the most common surgeries performed by vascular surgeons, with generally excellent results that have been prospectively validated in large series. Attention to technical perfection is crucial in maintaining these results. In our experience, one of the more common technical defects is an end point abnormality in a very cephalad internal carotid exposure.
These defects may occur for several reasons. Despite advances in preoperative imaging, carotid anatomy and pathology found at surgery do not always correlate with preoperative studies. Seven of the 14 patients were found at surgery to have a higher carotid bifurcation (five) or lesion (two) than expected. In this situation, a variety of maneuvers can be used to enhance exposure of the cephalad ICA. Anterior mandibular subluxation and nasal intubation during general anesthesia can be helpful if the need for high dissection is predicted by preoperative studies. Complete hypoglossal nerve dissection and mobilization, division of the posterior belly of the digastric muscle, division of the stylohyoid muscle, vertical mandibular ramus osteotomy, and styloidectomy6, 7, 8 are other maneuvers that can be used. Even with these adjuncts, achieving a satisfactory end point and closure in this setting can be difficult.
In addition to high lesions, another cause of distal defects is inadequate distal tapering of endarterectomized plaque. We have found that the latter defect is more common in eversion endarterectomy in which the end point can be difficult to visualize. Other causes include stenosis from patch closure, intimal flaps, severe kinking, and the need for repair stitches at the distal suture line.
Defects found that are not distal or that are thought to be at a location in which re-exploration and open revision can be achieved without difficulty are corrected in such a way. Surgical revision of distal defects, however, can occasionally be very difficult and yield unsatisfactory results. In addition, attempts at surgical correction can be time consuming and costly, and can increase the risk of complications. Cranial nerves at risk for injury with high dissection include the hypoglossal, vagus, glossopharyngeal, and marginal mandibular branch of the facial nerve. Prolonged surgical time can be problematic with cervical block anesthesia, which is associated with a fixed period of time. Carotid stenting can be relatively expeditious and can avoid complications related to the need for very high dissection. Although none of these lesions was necessarily too distal to at least attempt open correction, in most cases the hypoglossal nerve had been fully mobilized and the digastric muscle divided during the initial surgery. In light of our early dissatisfaction with re-exploration and open correction, as well as the good mid-term results associated with carotid stenting, this technique has become our preference.
Many, perhaps most, vascular surgeons do not perform completion studies after carotid endarterectomy. Ascher et al9 reported improved perioperative stroke and death rates when completion duplex scanning is performed and any significant defects are repaired. We have found arteriography to be reliable and expeditious, and find abnormalities that affect management in perhaps 5% of cases.10, 11, 12 Given the small margin that separates good from unacceptable results with this procedure, we feel imaging is justified, and we routinely perform completion arteriography using a butterfly needle inserted into the CCA.
With adjunctive stenting, we do not use a cerebral protection device (CPD) for several reasons. Some studies suggest that a CPD does not significantly reduce the incidence of embolic stroke during carotid stenting.13 Because the majority of atheromatous material has been removed at endarterectomy, the value of a CPD is less apparent. Because prograde flow is interrupted for stent deployment, we feel that with vigorous aspiration from the sheath before reflow, the potential for microembolism should be low.
Balloon dilatation, either before or after stent deployment, is typically not necessary. If stent deployment alone yields a satisfactory result, we believe that balloon dilatation would only increase the risk for disruption of the anastomosis or patch suture line. If a lesion cannot be crossed by the stent or if a significant residual defect remains despite stenting, then balloon dilatation should be used.
Ross and Ranval14 reported 13 cases of immediate intraoperative stenting to correct unacceptable distal ICA end points after endarterectomy. Two of their patients had stents placed for defects identified on completion duplex scanning. The remaining 11 patients received stents for defects noted by direct vision that were too cephalad for further surgical revision. Two of these 11 stents were placed before arteriotomy closure. The authors experienced similar satisfactory results, with no stent-related complications and the absence of significant restenosis with follow-up averaging 15 months.
We find intraoperative salvage carotid stenting to be an effective and safe adjunct to endarterectomy when unsatisfactory technical defects are identified at the cephalad ICA endarterectomy site. We believe that carotid endarterectomy and stenting need not always be competitive but rather complementary modalities to treat this difficult situation.
Author contributions
References
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Competition of interest: none.
CME article
PII: S0741-5214(08)00504-1
doi:10.1016/j.jvs.2008.03.054
© 2008 The Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.