Perforation of External Carotid Artery Branch Arteries During Endoluminal Carotid Revascularization Procedures

Introduction

Over 12,000 carotid angioplasty and stenting (CAS) procedures have been performed worldwide.¹ More than 130,000 carotid endarterectomies (CEA) are performed annually in the United States.² The FDA has already approved CAS with distal protection for high-risk patients. With the emerging data from ongoing trials demonstrating at least clinical equipoise with CEA, it is only a matter of time before CAS becomes the procedure of choice for patients with atherosclerotic carotid artery disease.^3,4 A wealth of experience in overcoming the technical difficulties and managing the complications that can be associated with endoluminal revascularization of the carotid artery has been accumulated, particularly at high-volume CAS centers, some of which have participated in the trials that have documented the safety of the CAS procedure. The external carotid artery (ECA) branches are often used to support the guidewire during removal of the diagnostic catheter and insertion of the guide sheath or catheter prior to performing neurointerventions such as CAS. This maneuver is considered safer than exchanging these devices with the guidewire in the common carotid artery (CCA) because it lowers the risk of prematurely crossing the internal carotid artery (ICA) lesion or showering embolic material into the intracranial circulation. Although we have performed CAS safely in over 1,000 patients, we have encountered four ruptures of ECA branches during planned CAS, 3 from wire perforations and 1 from a misdeployed PercuSurge balloon (Medtronic, Minneapolis, Minnesota). In this case series, we review our experience and describe the management of this potentially life-threatening complication. A discussion of several agents that can be used for therapeutic embolization of the ruptured blood vessel is provided. A review of our endovascular database consisting of more than 6,000 endovascular cases from 2001 to 2005 revealed 4 patients in whom an ECA branch rupture was encountered in the course of an endoluminal carotid artery revascularization procedure. The medical records and imaging studies of these patients were reviewed. Institutional Review Board approval (NSG0500104E) was obtained to conduct this retrospective study.

Cases

Case 1. A 61-year-old woman was found to have a severe left ICA stenosis during coronary angiographic evaluation before coronary artery bypass graft surgery (CABG). She was referred to our service for pre-CABG carotid artery revascularization. Diagnostic cerebral angiography documented an approximately 75% stenosis of the left ICA at the bifurcation as well as a high-grade stenosis of the petrous segment of the ipsilateral ICA and the proximal ECA. We decided to proceed with stenting immediately following the diagnostic angiogram. The patient received 3000 units of heparin, which resulted in an activated coagulation time (ACT) of 280 seconds, and a 135 mg bolus of Integrilin (Millennium Pharmaceuticals, Cambridge, Massachusetts), the later given due to concerns regarding the hemodynamic consequences of the stenosis in the petrous segment of the ICA. A 5 French (Fr) Vitek catheter (Cook, Bloomington, Indiana) inserted over a stiff exchange wire was used to gain access to the ECA in preparation for insertion of a 6 Fr Shuttle introducer sheath (Cook). At this point, the patient complained of difficulty clearing her throat and had difficulty swallowing. A left CCA angiogram was performed and documented a small amount of contrast extravasation as a result of perforation of a branch of the facial artery. Physical examination revealed significant parapharyngeal edema. An otolaryngologist and an anesthesiologist emergently evaluated the patient, and it was determined that she had a significant subglottic hematoma. The patient was electively intubated. The hematoma tamponaded the perforation, bleeding ceased, and no endovascular therapy was required. Protamine was not administered. After 48 hours, the hematoma had decreased in size enough to allow us to extubate the patient. The patient experienced no other symptoms, neurological or otherwise, related to this incident; and she recovered fully.

Case 2. An 83-year-old woman with a heavily calcified but asymptomatic left ICA stenosis was brought to the angiography suite for CAS. After gaining access to the left CCA with a diagnostic catheter, heparin was administered and her ACT was increased to 300 seconds. A glidewire was placed, with some difficulty, into the lingual branch of the ECA. The diagnostic catheter was exchanged for a 6 Fr guide sheath the tip of which was placed in the left CCA. An EPI FilterWire (Boston Scientific, Natick, Mass.) was used to cross the lesion and the filter deployed. Balloons (3 mm and 4 mm in diameter) were used to dilate the stenosis, but a stent could not be navigated through the stenosis and therefore the procedure was aborted and a completion left CCA angiogram was performed. Upon removal of the guide sheath, the patient immediately had difficulty talking and, on examination, she had both facial and tongue swelling. The contrast extravasation was not recognized at the time of the final angiogram and was only identified after the catheters had been removed and the patient became symptomatic. Protamine (30 mg) was administered. Despite the maintenance of adequate oxygen saturation throughout the episode, we decided to intubate the patient for airway protection. Due to the significant supraglottic swelling, routine intubation proved to be impossible and therefore the patient underwent emergent tracheostomy. The patient remained neurologically intact throughout these procedures. Four months later, the patient was weaned from her tracheostomy. Carotid Doppler evaluation at that time documented peak systolic velocities of greater than 500 cm/second in the left ICA. Six months later, the patient underwent a successful left CEA and, on follow-up, she has had no residual sequelae from her ECA perforation.

Case 3. An 85-year-old woman had an asymptomatic high-grade stenosis of the right ICA that had been evaluated with magnetic resonance angiography and Doppler ultrasound imaging. Cerebral angiography documented an 89% stenosis of the right ICA using North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria.5 She was enrolled in an ongoing CAS trial. After sufficient heparin was given to produce an ACT of greater than 250 seconds, a 5 Fr Simmons 2 catheter (Cook) was used to gain access to the right CCA. A stiff exchange wire was then placed in a branch of the occipital artery, and the Simmons 2 catheter was replaced with a 6 Fr Shuttle introducer sheath (Cook). The exchange was performed without incident. Right carotid angiography performed following insertion of the introducer sheath documented extravasation of contrast from the occipital branch that had been wired during the catheter exchange. Repeat angiography performed approximately 2 minutes later documented continued extravasation of contrast. On physical examination, the patient was neurologically intact and there was no compromise of her airway, but an enlarging sternocleidomastoid sheath hematoma was identified. At this point, a 6 Fr angled Envoy guide catheter (Cordis, Miami Lakes, Florida) was inserted through the introducer sheath and the ECA was selectively catheterized. A Prowler Plus microcatheter (Cordis) and a Transcend 14 microwire (Boston Scientific) were used to selectively catheterize the ruptured branch of the occipital artery. Angiography performed via the guide catheter documented the microcatheter occluding the perforated branch artery, whereas angiography performed via the microcatheter documented good positioning of the microcatheter with extravasation distal to the catheter tip. N-butyl-2-cyanoacrylate (NBCA) glue (Trufill, Cordis Corporation; 70:30 mixture) was used to occlude the vessel. Post-embolization angiography documented occlusion of the vessel and the absence of any further contrast extravasation. An ipsilateral subclavian artery angiogram was performed to ensure that there was no additional contrast extravasation as a result of collateral blood supply to the perforated vessel via the costocervical or thyrocervical trunks. Protamine was purposefully not given as the plan was to continue with the procedure after control of the ruptured vessel. Once the perforation was controlled, the patient’s CAS procedure was completed without further complications. The patient’s hematoma had greatly decreased in size by the following morning. There was no change in the patient’s neurological status as a result of this complication.

Case 4. A 62-year-old woman with an 80% asymptomatic carotid stenosis presented for CAS. After femoral artery access had been obtained, heparin was administered to attain an ACT of greater than 250 seconds. A 6 Fr angled Envoy catheter was placed in the left CCA. Because of the small size of the ICA, a PercuSurge balloon was chosen and deployed in what was perceived to be the distal ICA. On the subsequent guide catheter angiogram, contrast extravasation was documented. Protamine (30 mg) was administered. It was determined that the ascending pharyngeal artery, arising from the carotid bifurcation and lying adjacent to the ICA, had been mistakenly catheterized. The balloon was removed. A Prowler Plus microcatheter, in conjunction with a Transcend 14 microwire, was used to gain access to the ascending pharyngeal artery and for the delivery of three platinum coils that were successfully used to occlude the artery. There was no change in the patient’s neurological status as a result of this complication. The patient underwent emergent endoscopy performed by an otolaryngologist, which demonstrated only a small retropharyngeal hematoma. Three weeks later, the patient underwent successful CAS.

Discussion

We describe a series of patients with ECA branch artery perforation during planned CAS — a potentially life-threatening complication. When contrast extravasation can be visualized, the hemorrhage rate is at least 3 cc/minute.⁶ Unique to intraprocedural ECA branch artery rupture is the risk of loss of the patient’s airway. Once extravasation is documented, it is critical to ensure patency of the patient’s airway and to proceed quickly with selective catheterization and therapeutic embolization of the ruptured blood vessel. In patients in whom heparin is used, protamine can be given to reverse the effect of the heparinoids. Manual compression of the carotid artery is potentially useful, although we have not found it necessary. Endoscopic otolaryngological examination, emergent or elective intubation, and emergent tracheostomy, are all considerations in the event of this complication. Every angiographic suite performing CAS should have an emergency tracheostomy set available for use. The ECA branches present three important anatomic difficulties when considering embolization. First, the ECA branches, especially the neuromeningeal branch of the ascending pharyngeal artery, irrigate the lower cranial nerves, including IX, X, XI and XII. Secondly, there are extracranial-to-intracranial anastomoses that are variable among patients but which include communications between the ECA territory and both the ICA territory and the vertebral artery territory. When these communications exist, it is possible for an intracranial embolus to occur during an ECA embolization procedure. Finally, numerous collateral pathways exist between the branches of the ECA and other cervical arteries, such as the thyrocervical and costocervical trunks. The classic text book by Lasjaunias and Berenstein⁷ provides a detailed description of the ECA branches and an excellent discussion of potentially dangerous anastomotic connections. The goal of embolization in this setting should be to occlude the artery as close to the rupture site as possible. A complete discussion of all the possible embolic agents and the advantages and disadvantages associated with their use is beyond the scope of this article. All embolic agents should be regarded as potentially toxic substances. The choice of embolic agents will depend upon the lesion being treated, the vascular territory involved, the goal of the embolization procedure, and the degree of selectivity possible during catheterization. When choosing an embolic agent, characteristics to consider include the speed and reliability of delivery of the agent, the duration of the occlusive effect, and the risk the agent poses to adjacent normal tissue. There are many ways to categorize embolic agents. For instance, embolic agents can be absorbable or nonabsorbable, solids or liquids, pushable or flow directed, cytotoxic or noncytotoxic. Embolic agents include autologous blood, various gelatin sponge preparations, various particles, microcoils, and various liquid agents.^8,9 Autologous blood clot is easy to obtain and is inexpensive. It is an absorbable material and therefore it is a temporary agent. A small amount of topical thrombin can be added to a specimen of the patient’s blood to enhance clotting, particularly when the patient has been anticoagulated; and the addition of epsilon-aminocaproic acid (Amicar, Xanodyne Pharmaceuticals, Florence, Kentucky) can stabilize the clot and delay clot lysis. Of course, adding these agents to the blood increases both the cost and the complexity of the procedure. Because this material is not radiopaque, contrast enhancement is necessary to monitor the degree of embolization. Gelatin sponge (Gelfoam, Pharmacia & Upjohn Corporation, Kalamazoo, Michigan) has been used as an embolic material for many years. It is a temporary embolic agent because it is usually absorbed completely with little tissue reaction within 1-2 weeks. Gelatin sponge is an off-white, pliable, nonelastic, porous, and water-insoluble material that can be prepared in multiple ways for use in embolization, varying from large plugs to powder slurry. Angiographic contrast agents are often mixed with the gelatin sponge to help make it radiopaque. This material can be somewhat difficult to handle but it can be very effective, particularly when only temporary vessel occlusion is needed or desired. Silk suture is a material that is usually immediately available and is inexpensive.^10,11 It can be cut into pieces, and these can be injected or pushed into the vessel to be occluded. One of the authors (CAG) has found silk suture to be useful when it is only necessary to induce thrombosis of the vessel proximal to the bleeding site. One limitation of silk suture is that it is not radiopaque. Other particulate embolic agents include polyvinyl alcohol (PVA) particles and microspheres, trisacryl (acrylic co-polymer) gelatin microspheres (Embosphere, BioSphere Medical, Inc., Rockland, Massachusetts), and other similar materials. These agents can be sized or calibrated and are available in sizes from approximately 40–1,200 microns. PVA particles are irregular in shape and tend to clump both in the vessel and in the delivery catheter. Although PVA particles are considered to be a permanent embolic material, there may be a large volume of intraluminal thrombus relative to the volume of PVA within the vessel and, as a result of this, occasionally recanalization of PVA embolized vessels will occur. The various microspheres tend not to aggregate like PVA particles; therefore, the interventionist may be able to better control the embolization and achieve more distal embolization using microspheres.¹² Because these agents are not radiopaque, they are usually injected in combination with a contrast agent so that the embolization can be monitored. There are numerous embolic coils. Most of these devices are made of stainless steel or platinum, with the majority of microcoils being made of platinum. Embolic coils come in many shapes and sizes and can be bare metal or have attached fibers. They can be either separate pushable or injectable devices or attached to a delivery wire or catheter from which they can be detached once they are satisfactorily positioned. Vessel occlusion occurs as a result of device-induced thrombosis.

Recanalization of coil-embolized vessels is uncommon. One advantage of metal coils, and especially of detachable metal coils, is that they can be precisely positioned under fluoroscopic control. A disadvantage associated with the use of pushable and injectable coils is that the operator is committed once the coil is placed within the delivery catheter; the coils generally cannot be repositioned, and it is usually necessary to remove the catheter if, for whatever reason, the coil is not deployed. Another disadvantage of all coils is that they can prevent future access into the vessel in which they are placed. Liquid embolic agents include adhesive materials, such as NBCA; nonadhesive materials, such as Onyx (Micro Therapeutics, Inc., Irvine, California), which is a mixture of ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide; as well as sclerosants, such as absolute alcohol, sodium tetradecyl sulfate, and sodium morrhuate. The sclerosants are very unlikely to be used in the types of cases described above and will not be further discussed. Agents such as NBCA and Onyx are quite expensive and require considerable expertise to use safely. NBCA rapidly polymerizes on contact with blood or other ionic material. It is a tissue adhesive, and polymerization results in an exothermic reaction that causes additional damage to the vessel wall. NBCA can be opacified with metal powders and with iodized-oil contrast media. In our practice, NBCA (Trufill, Cordis) is usually prepared in a 70(lipiodol):30(NBCA) ratio, and several drops of glacial acetic acid are sometimes added to this mixture to further retard the polymerization time. In general, the catheter used for injection of NBCA can only be used once; therefore, if the embolization is incomplete, recatheterization of the target vessel may be necessary.¹³ Onyx is opacified with tantalum powder. When Onyx is injected into a vessel, precipitation and solidification of the polymer occurs, resulting in formation of a spongy material that is mechanically occlusive but which does not adhere to the vessel wall. Catheter occlusion is less common with Onyx than with NBCA. Dimethyl sulfoxide-compatible catheters are necessary when using Onyx.¹⁴

Conclusions

Rupture of ECA branches during planned CAS is a rare procedure-related complication. Due to the potential for producing airway compression and compromise, a retropharyngeal hematoma can be a life-threatening event. Physicians performing CAS should be aware of this complication and should be prepared to treat airway-related emergencies. They should also be familiar with and properly equipped to perform the embolization techniques that may be necessary to occlude the ruptured vessel. There are many techniques and agents that could be employed to treat iatrogenic injuries of the ECA and its branches. Sometimes bleeding can initially be controlled by occluding the target vessel with the tip of the catheter. Intentional intimal dissection might be considered as a method to occlude the vessel. Simple vessel injuries might be satisfactorily treated with temporary agents such as gelatin sponge, since the underlying injury would have a chance to heal during the time it takes for the gelatin sponge to be absorbed. Permanent agents such as coils might be easier to insert quickly and may be more efficacious in certain circumstances. It is best if a variety of embolic agents are immediately available to the interventionist. Interventionists should be knowledgeable regarding the vascular territory in which they are operating and should be experienced in the use of the available embolic agents.

Correspondence: recker@buffns.com