Embolization Therapy: Principles and Clinical Applications, 1 Ed.

Strategies for the Development of an Embolotherapy Service

Gary P. Siskin • John C. Dalfino

The growing role that embolotherapy has been playing in medical care should be apparent to all practicing interventionalists. As embolization procedures continue to either replace or play an adjunctive role to existing medical and surgical therapy, it becomes incumbent on those performing these procedures to assume the role of a treating physician and to assume significant responsibility for the care of these patients. This is the cornerstone of a true embolization service.

Physicians participating in an embolization service must have a complete working knowledge of the indications and contraindications for these procedures, the applicable vascular anatomy, the technical steps of the procedure, the embolic agent(s) and other equipment being used, the expected outcomes, and the potential complications and how these complications are best managed. This is a big task because embolization procedures are performed for various conditions falling under the domain of so many different medical specialties. In other words, the individual specializing in interventional oncology and spending much of his or her time performing procedures such as chemoembolization or radioembolization may not have the same degree of knowledge in the neuro or gynecologic applications of embolotherapy. The physicians performing these procedures must recognize these limitations if they are seeking to grow their practice into different areas. The technical skill-set and familiarity with embolic agents may be there, but a commitment must be made to the additional work required to claim the same degree of expertise as those regularly performing these procedures.

The knowledge base is only one part of this, though. For a successful embolization service to be in place within a hospital, interventionalists must make a true commitment to the care of these patients and the development of these procedures. Although it has been said frequently in recent years, no physician understands the role of and potential issues surrounding embolization procedures better than the person performing the embolization procedure. It is unreasonable to expect a gynecologist caring for a patient with fibroids undergoing a uterine artery embolization procedure, an oncologist caring for a patient undergoing chemoembolization, or a pulmonologist caring for a patient with a pulmonary arteriovenous malformation (AVM) undergoing embolization to understand the technical challenges, expected outcomes, and potential complications of the procedure better than an interventionalist. This fact alone should provide the justification for any interventionalist performing embolization procedures to be actively engaged in the longitudinal care of his or her patients.1

But there is more. Embolization has become the primary therapeutic options for so many different conditions, and as such, it is just inappropriate for the physician providing a therapeutic service to not be a part of the preprocedure and postprocedure care of his or her patient. This continuity of care is of course good for patients because the person with the most expertise with the procedure is keeping an eye on them. It is, however, also good for the physician. It is not possible to have a preprocedure conversation with a patient regarding expected outcomes and potential risks if one does not personally provide follow-up care. Without a suitable amount of postprocedure experience, one can never gain the familiarity with outcomes and complications to enable this type of conversation to take place. Therefore, this becomes inappropriate care and will likely form the basis for others to become actively engaged in embolotherapy.

All of this lends support to what is now becoming a mandatory clinical practice model for interventionalists performing embolization procedures. Interventional radiologists continue to be the specialists performing the largest volume of embolization procedures, but like so many areas under the heading of endovascular care, this is changing. A growing number of vascular surgeons, neurosurgeons, neurologists, and nephrologists are incorporating embolization into their procedural skill-set, and managing an entire episode of care is fundamental to their respective clinical practices. Although this is being increasingly recognized by interventional radiologists, there are some physicians who continue to either disagree with this model of practice or are not given the resources and/or support from their diagnostic radiology colleagues to become actively engaged in direct patient care. At some point, these physicians will have to make a decision regarding whether or not it is appropriate for them to continue performing these procedures. Longitudinal patient care is that important.


For most procedural specialists, the outpatient office forms the core of their practices. An increasing number of procedures are originating in the outpatient setting; therefore, an office must be available for an episode of care involving embolization to begin. The office is where patients are initially assessed and counseled, where arrangements are made for office or hospital-based procedures, where billing originates from, and where patients are seen in follow-up after procedures are performed.2 One need only take a quick look at this markedly consolidated list to understand that these items are difficult to administer from the confines of a fluoroscopy suite. Therefore, the core of an embolization service must take place in a dedicated office space in the community or hospital setting.

The physical space for an outpatient office represents only one part of this effort when establishing an embolization service. Successful practices are built around practitioners and staff who fully understand and appreciate the nuances of these procedures. Nurse practitioners3 and physician assistants4 have been playing an integral role within interventional practices for the past several years and will continue to do so. In the authors’ experience, these individuals are able to provide not only procedural assistance but also can truly be a valuable link between patients and the practice as they go through their procedural recovery. It always helps patients to know that they have points of contact within a medical practice should they have questions or concerns, and physicians who are able to share this responsibility with others are more likely to bring success to their entire practice in this area. Additional aspects of an outpatient office range from the office staff such as nurses, receptionists, and billing personnel to the computer-based electronic medical records that are prevalent today. These services need to be in place to ensure appropriate communication with referring physicians, consulting services, hospitals, and third-party payers.


Despite the different specialty backgrounds of physicians performing embolization procedures, these individuals are all asked in one manner or another to consult on a patient with a medical problem that may benefit from the procedures they offer. Keeping in mind the earlier point about who actually has the expertise about embolization procedures, it becomes the consultant’s responsibility to answer the referring physician’s questions and to determine if a patient is or is not a candidate for an embolization procedure. This commonly involves reviewing medical records, radiologic images, lab work, and the notes from previous procedures. An infrastructure must therefore be in place to ensure that this information is available for review at the time of an initial consultation. This information is often enough to determine a patient’s candidacy for embolization.

A discussion must then take place to review the decision-making process for determining why a patient is a candidate for embolization and why that procedure is being recommended. The procedure should be reviewed in its entirety with the patient, especially if they may be only minimally sedated; they will likely be more comfortable if they know what is happening. Almost more importantly, expectations for recovery should be reviewed as well. Patients undergoing embolization often have the idea that a “procedure” such as embolization cannot possibly be associated with a difficult recovery period (“it is not surgery”). Although this may be true in some instances, the various chapters in this textbook clearly demonstrate that the recovery after some embolization procedures may be difficult for these patients and the families caring for them. The expected postprocedure symptoms, the duration of this recovery, and the ways to get in touch with staff at all hours of the day need to be reviewed with patients and their families.

The final step in this preprocedure consultation is to be certain that patients understand not only the procedure but also the role that this procedure is playing in the overall management of their condition. For some patients, surgery may follow an embolization procedure, whereas for others, particularly in the area of interventional oncology, liver-directed therapy may be followed by surgical or medical therapy. Patients need to understand when embolization is a stand-alone treatment and when it is one step in a long process involving many treatment strategies offered by many different physicians. The same conversation should be had with the physician referring the patient to your service because they should also understand when additional therapy may or may not be required after embolization. This is important in both the inpatient and outpatient setting.


The base of knowledge required for successful performance of embolization procedures has been extensively reviewed throughout this textbook. It should be said here, though, that patients must feel that they are being treated by physicians who have and are comfortable with the knowledge and technical skill required to treat their condition successfully. Ensuring that patients have this type of confidence in their physician goes a long way toward increasing their comfort as they enter a procedure suite for their embolization procedure.

No matter how confident patients are with their physicians, and no matter how eager they are to have this procedure performed, most patients will prefer to be adequately sedated throughout the course of an embolization procedure. Therefore, physicians actively participating in an embolization service and regularly performing these procedures must have a good understanding of the sedation needs in association with the procedure being performed and the sedation demands of the individual patient. This should be a point of discussion during a preprocedure consultation. For some embolization procedures, general anesthesia may be required, but in the author’s experience, most embolization procedures can be performed successfully with moderate sedation using drugs such as midazolam and fentanyl. Use of these medications will require appropriate monitoring of patients during and after the performance of the procedure.

The risk of transient bacteremia after embolization has been historically demonstrated,5 which is why interventionalists participating in an embolization service should have an understanding regarding the use of prophylactic antibiotics before these procedures. Practice guidelines from the Society of Interventional Radiology have recommended the use of prophylactic antibiotics targeted against skin pathogens before solid organ embolization procedures involving the liver, kidney, or spleen, especially when there is a high likelihood of infarction; this includes chemoembolization procedures.6 Prophylaxis is also recommended before uterine fibroid embolization procedures, although there is no consensus regarding antibiotic use when embolization is being performed to control bleeding from a viscus or solid organ.6


The recovery period after embolization is the greatest area of opportunity for physicians participating in an embolization service. It is here that patients will judge the care that they received. Remember that there is rarely any visible manifestation of the procedure that was just performed. Most patients leave an interventional procedure area with nothing more than a Band-Aid as evidence that they underwent a procedure. There is no surgical incision closed with obvious attention on cosmetic healing to confirm the technical proficiency of the surgeon. Therefore, patients are left assuming that the job was done and was done well. Managing patients after an embolization procedure represents the real opportunity physicians have to demonstrate their caring and their expertise; it is what the patients will remember. Therefore, physicians must be certain that patients and their families are adequately counseled regarding the expected symptoms after embolization. In addition, an easy means of communication between patients and the physician practice must be established to address questions and/or concerns during this recovery period.

Postembolization Syndrome

The different applications of embolization are each associated with a unique set of postprocedural issues that need to be recognized and addressed by the treating physician. These are all specifically discussed in previous chapters of this textbook. However, patients undergoing solid organ or solid tumor embolization typically experience a postembolization syndrome that has been well described in the literature. For any patient undergoing procedures such as chemoembolization, splenic artery embolization, uterine artery embolization for fibroids, and renal artery embolization for an angiomyolipoma (to name a few), patients should be appropriately counseled regarding the symptoms that make up the postembolization syndrome. Interestingly, some consider postembolization syndrome to be a complication of an embolization procedure, but these authors disagree. The postembolization syndrome is an expected consequence or side effect of solid organ or solid tumor embolization, and patients should expect to experience the associated symptoms with variable degrees of intensity.7 Symptoms severe enough to require readmission to the hospital after discharge should be considered a complication.7

The clinical manifestations of postembolization syndrome include pain, fever, nausea and vomiting, loss of appetite, and generalized malaise. These symptoms generally occur within 1 to 3 days after embolization and are believed to be a consequence of the tissue ischemia induced by the procedure. Tissue breakdown products may induce an inflammatory response and the production of cytokines. It has been suggested that it may be mediated by interleukins 1 and 6 and by tumor necrosis factor-alpha.8,9 They may be responsible for the pain, fever, and nausea commonly seen after embolization. Leukocytosis in the first 24 hours after embolization is common as well. This needs to always be considered if evaluating patients shortly after embolization because a failure to recognize this may cause one to be overly concerned about early infection.10 Experience suggests that even though these symptoms occur in most patients undergoing solid organ or solid tumor embolization, they can be more severe in patients in whom a large tumor volume was embolized or a large volume of normal tissue was embolized.

The symptoms associated with the postembolization syndrome are typically self-limited for most patients. However, effective management can improve patient comfort and lead to a more rapid recovery after embolization. The medications used can be directed toward which symptoms the patient is actually experiencing, including anti-inflammatory, antipyretic, and antinausea medication. Pain medication should be an important part of the medication regimen for patients experiencing pain after embolization. Generally speaking, the efficacy of a pain regimen is often enhanced by the additive effect of two analgesics that relieve pain by different mechanisms.11 Although prophylactic medication may be appropriate in some settings, it is important to remember that medications have their own side effects that can actually prolong the recovery period. For example, opioid analgesics are effective at addressing pain after embolization but can contribute to both nausea and constipation that many patients experience. These symptoms can make a recovery period more difficult, so careful use of these medications is recommended, but if needed, additional medications can be offered to address their side effects.


Prolonged symptoms after embolization should always raise the possibility of an infection. In general, fever starting or worsening after postprocedure days 5 to 7 should increase one’s suspicion for infection. Other symptoms may lead one toward a diagnosis of infection as well, including a foul-smelling discharge after uterine artery embolization for fibroids.12 Cultures should be obtained and antibiotic therapy can be initiated at that time. Imaging may be challenging to interpret because gas may be present within a solid organ after embolization; it does not necessarily mean that an infection or abscess is present.

It is also possible for infections to take place after embolization due to colonization of coils, which can act as a foreign body nidus.13 An infection can be attributed to coil colonization if there is a short time interval between coil placement and the onset of the infectious event, if the causative organism is a part of normal human flora, if the infection is found to be located around the coils, and if other concurrent infections are not present.14 If this should occur, the causative agent can penetrate through the wall of the artery and cause a parenchymal infection. This can cause a significant inflammatory response and edema, which can predispose the patient to formation of an abscess.13 If this occurs, removal of the infected coil is the chosen treatment, but if this is not possible, then prolonged high-dose intravenous (IV) antibiotics is a suitable alternative.

Neurologic Issues


Headache is a fairly frequent complaint following cerebral angiography and interventions. Baron et al.15 found postprocedural headaches to be common after coil embolization (72%), glue embolization (33%), and stent placement (14%). In this series, 118 urgent diagnostic studies were performed to further evaluate these headaches, all of which were negative.15 Although there is no robust data supporting any particular criteria for imaging for the workup of postangiography headache, it is probably prudent to consider imaging in patients who complain of severe headache that is not relieved by a dose of narcotics or when accompanied by abnormal neurologic findings. The use of glucocorticoids can be considered prophylactically or posttreatment in patients undergoing embolization of AVMs or tumors to avoid headaches due to cerebral edema.

Cranial Nerve Palsies

Cranial nerve palsies can occur after both intracranial and extracranial embolization procedures. During extracranial embolizations, such as for glomus jugulare tumors, cranial nerve palsies are usually caused by inadvertent embolization of the vasa vasorum of the cranial nerves.16 These injuries can occur with both particulate and liquid embolic agents, although they tend to be transient when particulate agents are used and more permanent when liquid agents are used.17 Although these injuries are probably not completely avoidable, positioning the catheter tip as close as possible to the target lesion will reduce the risk of embolizing, noninvolved vessels. Embolization with liquid embolic agents carries the additional risk of traction injuries to adjacent cranial nerves during catheter removal. For instance, transient facial and V3 palsies have been reported after catheter extraction from Onyx (Covidien, Irvine, California). casts in the middle meningeal and internal maxillary arteries after embolization of dural arteriovenous fistulas (dAVFs) and AVMs.18

Ischemic Stroke

Ischemic stroke can occur from any intravascular procedure in which the aortic arch, precerebral, or cerebral vessels are accessed. Most strokes related to diagnostic or interventional angiographic procedures occur during the procedure itself. Less commonly, a stroke can occur in the postprocedure period. In either case, prompt recognition of ischemic complications is essential so that corrective action can be taken as soon as possible.

Immediately following arch or cerebral angiography, it is advisable to check the patient for evidence of stroke by performing a neurologic exam. The Cincinnati Prehospital Stroke Scale (CPSS) is a validated tool for identifying stroke in both the inpatient and outpatient setting. The patient is assessed for facial droop, upper extremity drift, and aphasia. A positive score on any of these items will identify nearly 90% of anterior circulation strokes.19 If a stroke is suspected, the patient should have a noncontrast CT scan performed to rule out intracranial hemorrhage. Unless otherwise contraindicated, IV tissue plasminogen activator can be administered. Depending on the severity and suspected cause of the stroke, consideration should be made for acute endovascular clot thrombolysis.


A quality improvement program should be an important component of an embolization service. Specifically, interventionalists should collect and evaluate data to determine the appropriateness of the indications they use for embolization, the degree of success they are achieving after these procedures, and the incidence of complications after embolization.20 This enables interventionalists to identify problems and to put corrective measures in place with the goal of improving the quality of care.21 Ultimately, this type of effort can demonstrate the ongoing value of embolotherapy to the patients being served and can help ensure the growth of this area of medicine.22


Even with all of the previously described pieces in place, ongoing work is required to manage and grow an embolization service. At the specialty level, research is continuously required to understand the place of embolization in the care of the many patients described throughout this textbook. Comparative effectiveness studies simply have to get done to best understand the role of embolization as opposed to hysterectomy for fibroids, chemotherapy or radiation for cancer, or surgery for trauma. Without an organized effort to carry out this type of research, questions will always linger about the superiority, equivalence, or inferiority of embolization as treatment for many of the conditions described in this textbook.

At the local level, efforts should always be made by those participating in an embolization service to educate everyone involved in patient care. Direct outreach to patients is an appropriate way to make them as well as advocacy groups aware of these procedures as treatment options that should be discussed with physicians. Referring physicians should know about all treatment options available to their patients and not just the ones offered by members of their own specialty. Finally, hospital administrators and third-party payers should always be enlightened regarding the benefits of these procedures from a cost-savings perspective and from the potential growth and attention they can bring to an institution.


Embolization has progressed to the point where dedicated expertise is required for success. The expertise that the interventionalist brings to the care of patients requiring embolization is significant and should be treated as such. Physicians with this expertise are encouraged to develop and participate in an embolization service. This can help ensure that patients being served by these physicians and these procedures are receiving care that exceeds expectations.


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