Iatrogenic postsurgical pseudoaneurysms of the carotid arteries are rare complications, with an incidence of 0.7% (1, 2). The technical difficulty and morbidity in surgical treatment of carotid pseudoaneurysms makes a less invasive endovascular approach an attractive alternative (1, 2, 3, 4, 5, 6, 7). Recently, the applications of self-expandable polytetrafluoroethylene-covered stent-grafts have been extended to the carotid arteries, leading to instantaneous restoration of the vessel wall (2, 3, 4, 5, 6, 7).
Microvascular free flap transfers are frequently necessary to close complex head and neck defects resulting from radiation and extirpative surgery. The timing of secondary neovascularization remains controversial (8). We describe a unique case of a patient who survived two carotid artery sentinel bleeding episodes, the second of which included two iatrogenic external carotid artery pseudoaneurysms. Successful covered stent-graft treatment 6 weeks after reconstruction with a complex free flap excluded the flap's vascular pedicle without compromising its viability.
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A 45-year-old man presented with recurrent squamous cell carcinoma in the right retromolar trigone and underwent wide resection, hemiglossectomy, segmental mandibulectomy, and tracheostomy. Reconstruction was performed with a chimera free flap with microvascular anastomosis to an external carotid artery branch vessel. Eighteen days later, the patient presented with sentinel arterial bleeding through the incision site requiring emergent surgical exploration. An iatrogenic injury in the proximal external carotid artery just distal to the carotid bifurcation was repaired. Additionally, revision of the flap anastomosis was required as the external carotid artery was surgically clipped distally, turned inferiorly, and reanastomosed to the flap pedicle end to end. Three weeks later, the patient returned with an expanding pulsatile neck mass and erythema of the flap tissue. Digital subtraction angiography confirmed a 12-mm pseudoaneurysm arising from the proximal right external carotid artery in close proximity to its origin and extravasation 2 cm distally into a 20-mm × 40-mm pseudoaneurysm cavity, where the external carotid artery had recently been anastomosed to the flap's vascular pedicle (Fig 1a).
Under general anesthesia, the patient was administered dual antiplatelet therapy (600 mg clopidogrel and 325 mg aspirin loading bolus) through a gastrostomy tube and anticoagulated with intravenous heparin (activated clotting time >300 seconds). A 4-F angled glide catheter was advanced over a 0.035-inch glidewire to catheterize the right internal carotid artery. Stiff wire exchange allowed retrograde placement of an 8-F × 90-cm guide sheath into the proximal right common carotid artery. Subsequently, a Fluency 7-mm × 40-mm covered stent-graft (Bard Peripheral Vascular, Tempe, Arizona) was advanced and deployed across the carotid bifurcation, excluding the external carotid artery pseudoaneurysms (Fig 1b,1c).
After endovascular treatment, the neck hematoma (Fig 2a) was surgically evacuated and the external carotid artery was ligated at its origin to prevent a retrograde endoleak, but the flap appeared intact upon direct inspection and revision was not performed. Postoperatively, the soft tissues of the flap remained viable, and a triphasic bone scan performed 2 days later revealed excellent blood flow to the osseous component of the flap (Fig 2b).
Doppler ultrasound studies and clinical follow-up at 1, 3, and 6 months confirmed stent-graft patency without in-stent thrombus or stenosis. Interval healing of the flap was observed with reduced swelling and erythema (Fig 2c). The patient continued to receive long-term broad-spectrum antibiotics and antiplatelet therapy without bleeding, flap necrosis, infection, or thromboembolic complications.
Unlike in dissecting aneurysms, the natural course of untreated traumatic or iatrogenic pseudoaneurysms is not well studied (2, 7). In most patients, emergent treatment is initiated to prevent catastrophic hemorrhage (1, 2, 3, 4, 5, 6, 7).
Open surgical ligation or bypass of carotid pseudoaneurysms with the use of prosthetic or autogenous vein grafts entails technically demanding exposure of the skull base with relatively high morbidity and complication rates of ischemic injury or cranial nerve deficits, especially in hostile surgical or radiated necks (1, 2, 3, 4, 5, 6, 7). Moreover, surgical or endovascular vessel deconstruction requires a balloon test occlusion study to assess the tolerance of sacrificing the intracranial supply, often not feasible in an emergent setting with up to 10% false-negative findings resulting in ischemic complications (1, 2, 3, 4, 5, 6).
Endovascular stent placement has been shown to be effective in treating symptomatic or expanding dissecting aneurysms of the carotid arteries (1, 2, 3, 4, 5, 6, 7). Although bare uncovered stents can induce flow remodeling and thrombosis of small aneurysms, turbulent flow into wide-necked aneurysms and large pseudoaneurysms requires coil embolization through the stent matrix.
Self-expanding covered stent-grafts provide an elegant endovascular solution with rapid atraumatic deployment, immediate vessel reconstruction, complete aneurysm exclusion, and salvage of intracranial flow (2, 3, 6, 7). Covered stents have been previously described in the treatment of traumatic carotid pseudoaneurysms and fistulas (4, 5, 6). Other reports demonstrate their successful deployment in carotid “blowouts” from complications of advanced head and neck cancer (1, 3, 7). However, it is important to note that these indications are considered off-label applications as covered stents were primarily designed for larger and less tortuous vessels (2, 3, 4, 5, 6, 7).
Detailed morphologic assessment with three-dimensional digital subtraction angiography or computed tomographic angiography imaging is recommended for appropriate selection of stent-graft dimensions, reducing the risks of vessel dissection/perforation, incomplete apposition, and thromboembolic complications (1, 2, 3, 4, 5, 6, 7). In addition, complete diagnostic cervical angiography can be valuable in assessing any collateral flow to the pseudoaneurysm cavity via the bilateral external carotid, thyrocervical, costocervical, or vertebral arteries. In deploying a covered stent across the external carotid artery origin, the potential for a type 2 endoleak exists and coil embolization of the external carotid artery origin is advised before stent-graft deployment, especially in traumatic pseudoaneurysms with an intact external carotid circulation (1, 2, 4, 5). However, if injury involves the carotid bifurcation or external carotid artery origin, endovascular sacrifice of the external carotid artery trunk may be technically difficult, with risk of complications during manipulation and coil embolization. As in our case, the external carotid artery origin can be easily addressed with surgical clipping if subsequent exploration or evacuation is planned.
Limitations arise mainly from the high-profile construction and poor trackability of covered stents with cumbersome 7–9-F guide sheath delivery systems. Other factors to consider include stent-related thrombogenicity, coagulopathic patients, vessel tortuosity, or peripheral vascular disease limiting large guide sheath placement. In addition, the radial force of self-expanding covered stents may be insufficient to restore the lumen diameter in the presence of an underlying stenosis (1, 2, 3, 4, 5, 6, 7).
In carotid blowouts secondary to head and neck cancer, stent-grafts should be judiciously placed in chronic infected necks, dehiscent open wounds, or in cases of exposure to the pharyngeal airway. Stent infection can lead to grave complications of graft breakdown, periluminal abscess, vessel occlusion, and/or septic thromboemboli. If a covered stent must be deployed in this setting, we advocate extended broad-spectrum antibiotics for several months to cover aerobic and anaerobic pathogens (1, 3, 7).
To prevent thromboembolic complications, aggressive intraprocedural anticoagulation with heparin and dual antiplatelet therapy are essential. Although we routinely prescribe antiplatelet agents for 3–6 months after carotid stent implantation, recent studies indicate that long-term therapy does not appear to be necessary in the case of polytetrafluoroethylene-covered stents as a result of early stent endothelialization (2, 7). Extended dual antiplatelet therapy with aspirin and clopidogrel can lead to serious adverse reactions and hemorrhagic complications such as allergic rash, diarrhea, neutropenia, thrombotic thrombocytopenic purpura, spontaneous hemorrhage, surgical blood loss, and need for blood or platelet transfusions.
Chimera flaps have multiple independent tissue components with separate pedicles attached to a common source vessel. The time required for adequate flap neovascularization and independence from their anastomosis remains controversial and is thought to be related to the volume of flap–to–surface area contact ratio and the quality of the wound bed (8). Endovascular exclusion of a flap's arterial supply may not compromise its viability if recruitment or development of collateral circulation has occurred. Controlled animal studies may be helpful in delineating the specific time required for neovascularization to occur in flaps of different volumes and to assess exogenous promoting or inhibiting factors. In our case, the external skin paddle of the chimera flap was elevated 18 days after reconstruction and its vascular pedicle was occluded with a covered stent-graft 3 weeks later, nearly 6 weeks after flap placement, without evidence of vascular insufficiency or flap necrosis.
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