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Endovascular Repair of a Carotid Pseudoaneurysm with
Fluency® Plus Stent Graft Implantation
Pseudoaneurysm formation is a rare complication following carotid endarterectomy (CEA), with an incidence of less than 1% of cases.1 Treatment of this complication is challenging. The current standard of care is some form of repair rather than conservative management. Open surgical repair has long been the treatment of choice.2 Recently, endovascular techniques have offered a less invasive approach. We report a case of pseudoaneurysm following CEA treated by percutaneous Fluency® Plus (Bard Peripheral Vascular, Tempe, Arizona) stent graft implantation.
Case Report. A 76-year-old male was admitted to our hospital because of a tight stenosis in the proximal segment of the left internal carotid artery (ICA). Routine CEA was performed, and the arteriotomy was sutured with Dacron-patch angioplasty (HemaCarotid Knitted Ultrathin Patch, Intervascular®, La Ciatat, France). The patient was discharged on the second postoperative day.
Seven months after CEA, a color-Doppler echography revealed a pseudoaneurysm (1.5 x 1.0 cm) arising from the left common carotid artery (CCA) at the site of the endarterectomy and patch implantation (Figure 1) just below the bifurcation of the external carotid artery (ECA) and ICA. The mean CCA diameters in the segments distal and proximal to the pseudoaneurysm were 8.5 mm and 12 mm, respectimvely. The pseudoaneurysm was not filled with thrombus and the ipsilateral ICA and ECA were patent. The contralateral carotid system did not have significant stenosis. Blood chemistry analysis did not show any sign of inflammation (leukocyte count was 7.4 x 109/L; C-reactive protein was 3 mg/L). Furthermore, a radionuclide scan using labeled leukocytes ruled out the presence of infection at the pseudoaneurysm site. However, antibiotics were intravenously administered.
Two approaches were proposed to the patient and to the referring physician: (1) a surgical approach via direct suture or autogenous saphenous vein reconstruction; or (2) a percutaneous approach via covered stent implantation (Fluency® Plus stent graft; Bard Peripheral Vascular Inc., Tempe, Arizona) (Figure 2). The patient and the referring physician chose the percutaneous approach. Since the device was not approved for this indication, a request for use on compassionate grounds was granted.
The patient was loaded with 300 mg of clopidogrel on the evening prior to the procedure and was taking 100 mg of aspirin daily. The procedure was performed by combined radial and femoral approaches. Intravenous unfractionated heparin (total dose of 10,000 units; activated clotting time > 300 seconds) was intravenously administered. A 6 Fr Pigtail catheter was advanced into the aortic arch through the right radial artery in order to perform left carotid arteriography. Digital subtraction angiography (DSA) confirmed the presence of a pseudoaneurysm in the distal segment of the CCA, 1 cm below the ICA and ECA origin (Figure 3A).
After cannulation of the right common femoral artery with a short (11 cm) 10 Fr sheath (Super Arrow-Flex®, Arrow International, Reading, Pennsylvania), a 5 Fr Junkins R4 diagnostic catheter was advanced into the left ECA. The 0.035 inch superstiff Amplatz long (260 cm) guidewire (Meditech, Boston Scientific Corp., Natick, Massachusetts) was advanced through the lumen of the diagnostic catheter into the left ECA. A self-expanding covered stent (Fluency Plus stent graft, 12 mm in diameter, 40 mm in length) was advanced through the Amplatz super-stiff guidewire and positioned at the pseudoaneurysm site. Postdilatation was then performed using a 9 mm x 4 cm long balloon (Euca PX, Eucatech AG, Gottlieb-Daimler-Strasse 5, Germany). DSA of the left carotid system showed complete pseudoaneurysm exclusion and good patency of the ECA and ICA (Figure 3B). The femoral entry site was closed using a Perclose closure device (Perclose Inc., Redwood City, California). There were no neurological or other complications. A color Doppler echography performed the day after the procedure confirmed optimal stent apposition and complete pseudoaneurysm exclusion. There was no flow in the aneurysmal sac. The patient was discharged home on the second day after the procedure. No major adverse cerebrovascular events occurred at 30-day follow up. An echo-color Doppler at 3 months confirmed pseudoaneurysm sealing and good patency of the ECA and ICA (Figure 4).
Discussion. Pseudoaneurysm formation is a rare complication following CEA, with an incidence of less than 1% of cases.1 The mechanisms underlying pseudoaneurysm formation following CEA include suture failure, degeneration of the arterial wall or patch material and infection.1–3 Pseudoaneurysm formation is thought to be somewhat more common after patch repair than primary closure CEA.3 Pseudoaneurysm may occur as early as 6 weeks and as late as a decade after the original procedure. Presentation is usually asymptomatic, often a pulsatile lateral neck mass. Other clinical manifestations are stroke, infection or ruptures.1–3 The diagnosis is readily verified by duplex scan and confirmed by arteriography, magnetic resonance or computed tomography angiography.
Treatment of this complication is challenging. The current standard of care is some form of repair rather than conservative management. Open surgical repair has long been the treatment of choice.3 Reconstruction is best accomplished with a saphenous vein interposition or extended angioplasty. In one report that discussed carotid artery ligation, this procedure was required for 22.7% of patients who had infected carotid artery pseudoaneurysms, with a resulting death or major stroke rate of 50%, as compared to a 12% risk following arterial reconstruction.2 More recently, endovascular techniques have offered a less invasive approach. The best endovascular strategy is not yet clear. Three main endovascular techniquesfor carotid pseudoaneurysm repair have been reported.4–13 The most commonly used technique has been endoluminal stent placement across the neck of the pseudoaneurysm with subsequent coiling.5–7 Even though clearly successful in the short term, the sac is not totally excluded from the systemic flow and could still enlarge due to the continued transmission of arterial pressure. This approach is associated with the risk of coil embolization. Another endovascular technique is the percutaneous injection of thrombin. Holder et al8 treated a right common carotid artery pseudoaneurysm by percutaneous injection of 250 units of human thrombin into the sac. Such a technique requires a long neck connecting the artery to the sac; a short neck (such as the index case) increases the risk of complication due to thrombin leaking into the systemic circulation. Implantation of covered stents or stent grafts represents another endovascular option. This approach enables total exclusion of the aneurysmal sac, with limited risk of distal embolization. Although sometimes used,9–13 balloon-expandable covered stents are susceptible to crushing and collapse.14,15 Self-expanding stent grafts represent the ideal option. At present, no stent graft is approved for this indication. Gupta et al13 recently reported a case of giant post-CEA pseudoaneurysm successfully treated by Viabahn stent graft implantation. The Viabahn prosthesis is a self-expanding nitinol stent covered internally with ultrathin expanded PTFE. This stent is resistant to deformation by mechanical forces due to its exoskeleton’s longitudinal flexibility and shape memory. Experimental studies in canine iliofemoral arteries have shown that the PTFE graft material promoted rapid endothelialization of flow surfaces, which may reduce the risk of thrombosis.16 The Fluency Plus PTFEcovered nitinol stent-graft (Bard) is a self-expanding nitinol stent encapsulated within two ultrathin layers of ePTFE. The laminal surface of the ePTFE is carbon-impregnated. This stent graft offers a perfect balance of desirable characteristics: radial strength, flexibility, minimal foreshortening, low profile, placement accuracy and convenient deployment in an easy-touse pullback delivery system. The Bard SAFE™ Delivery System features an optimal balance between shaft pushability and progressive flexibility at the catheter tip, providing excellent trackability to the target lesion site. The highly radiopaque Puzzle™ tantalum markers provide superior fluoroscopic visualization throughout the entire stent graft placement. The excellent radial expansion force, in combination with the 2 mm flared ends, minimize the risk of stent graft dislocation or migration.
In the case reported by Gupta et al,13 the use of a single femoral approach was possible because they used an 8 mm Viabahn stent graft, which is 9 Fr-compatible. We used the combined radial and femoral approaches to overcome the problem of the large (10 Fr) sheath size necessary to advance the 12 mm Fluency Plus stent graft. To the best of our knowledge, the largest long introducer sheath available is 9 Fr.
Significant drawbacks of the stent graft are: the possibility of infection, the risk of side branch occlusion, the limited flexibility of the available covered stents, the risk of rupture and the risk of access site complications due to the large sheath size. An infected pseudoaneurysm is an absolute contraindication for endovascular repair and warrants open surgical resection. Although most often associated with signs of infection, sometimes the only clue may be a positive culture from the surgical specimen.3,17 Fortunately, in the era of modern antibiotics, the development of an infected pseudoaneurysm following CEA is very rare.3,17 The risk of side branch occlusion is also a significant drawback. In cases where lesions are close to the carotid bifurcation, the ECA may be compromised. Finally, the limited flexibility of the available covered stents is a disadvantage. Because of this, only straight and accessible vessels can be targeted. In the present case, the takeoff of the left CCA from the aortic arch was favorable, without substantial tortuosity and/or angulation. Furthermore, the rigidity of the Amplatz guidewire allows easy passage of the stent graft into the CCA. There is the risk of rupture and of distal embolization due to intravascular manipulation near a pseudoaneurysm. And finally, the risk of access site complications dueto the large sheath size must be considered. However, the risk of surgery is high.2–3 Development of smaller, more flexible self-expanding covered stents may overcome some of the present technical limitations.
Conclusion. Endovascular stent graft repair for carotid pseudoaneurysm is a promising technique. Long-term data and large case series will be needed to establish the role of this technique for the treatment of carotid pseudoaneurysm.
References
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