Journal of Vascular Surgery
Volume 43, Issue 2, Supplement , Pages A3-A5, February 2006

Starting a program for endovascular thoracic procedures: Challenges and solutions

  • Mark K. Eskandari, MD

      Affiliations

    • Corresponding Author InformationCorrespondence: Mark K. Eskandari, MD, Division of Vascular Surgery, Northwestern Memorial Hospital, Galter 10-105, 201 East Huron Street, Chicago, Ill 60613

Northwestern University Feinberg School of Medicine, Chicago, Ill

Received 20 October 2005; accepted 23 October 2005.

Article Outline

 

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Introduction 

Endoluminal exclusion of thoracic aortic aneurysms (TAAs) is now more than theoretically appealing, in large part because of the availability of an approved device. Currently, only the Gore Thoracic Aortic Graft (TAG) endoprosthesis (W. L. Gore & Associates, Inc, Flagstaff, Ariz) has United States Food and Drug Administration (FDA) approval for the treatment of TAAs.1 Other devices will likely follow suit in the near future, including the Talent Endoluminal Stent-Graft System (Medtronic AVE, Inc, Santa Rosa, Calif) and the Cook Thoracic Stent-Graft (Cook Inc, Bloomington, Ind).2, 3

The development of a successful endovascular thoracic aneurysm program requires more than just devices, however. An institutional commitment, not only in the form of capital expenditures but also with regard to subspecialty overlap, is mandatory. Although the treatment of peripheral vascular disease has traditionally been managed by vascular surgeons, the development of minimally invasive endovascular therapies is also in the hands of interventional radiologists, interventional cardiologists, and, for thoracic aneurysms, cardiothoracic surgeons. This chapter reviews some of the local challenges that must be overcome to establish a successful endovascular thoracic aortic aneurysm program.

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Capital expenses 

Imaging systems 

Successful endovascular treatment in all vascular beds requires optimal imaging, and this is particularly important in the case of TAA repair. Although this is a procedure that can be performed with the use of a portable fluoroscopic imaging unit (ie, OEC 9800, GE Healthcare, Milwaukee, Wisc) and a corresponding table, this is not optimal for a number of reasons, including poor image quality, limited rotational ability, small field of view, and tendency to “overheating.” The tortuosity of the thoracic aorta and proximity to crucial vessels such as the subclavian, carotid, and celiac arteries mandate the ability to clearly delineate the exact origin of these vessels in relation to the aneurysm and intended “seal zones.” Adjunctive imaging with intravascular ultrasound or transesophageal echocardiography may be helpful but requires more equipment and added skills, including performing the procedure and interpreting the information.4

Inadequate visualization of the anatomy can lead to devastating complications, ranging from inadvertent coverage of arch or visceral vessels to missing a proximal type I endoleak or dissection. Intraprocedural imaging is more extensively covered in a separate chapter, but suffice it to say here that a fixed fluoroscopic unit with a wide field of view (ie, 15-inch image intensifier) is ideal.

Another aspect of imaging that deserves mention is that of preprocedural and postprocedural follow-up. Much of the decision to use an endograft for a thoracic aneurysm is dependent on the objective measurements obtained on thin-cut, high-resolution computed tomography (CT) scans and diagnostic angiography. The latter is less frequently used with improvements in CT imaging and three-dimensional-rendered images. CT is needed to choose the appropriate size and length of devices and to identify seal zones, anomalous anatomy, extent of calcification, vessel tortuosity, and intraluminal thrombus load. After implantation, CT is used to document complete exclusion of the aneurysm and to detect endoleaks, vessel coverage, retrograde dissection, migration, or component failure (ie, fracture, kinking, and fabric tears).5 Needless to say, availability of high-quality CT imaging is a must.

Procedurals suite 

The prerequisite of high-resolution image guidance is a natural introduction to where these procedures should best be done. Thoracic endografts have been designed to be delivered transfemorally, either through an open approach or percutaneously; however, anatomic constraints may necessitate alternative entry sites.6 Most frequently this is through a retroperitoneal approach to the iliac vessels or infrarenal aorta. In the operating room this is readily achieved, whereas in an interventional suite it can be fraught with the problems of poor lighting, insufficient technical assistance, and an inadequate sterile environment. Additionally, performing these procedures in a fully functional operating room allows the operator to deal with unexpected complications in an expeditious manner with complete anesthetic support.

Available inventory 

Current thoracic endograft systems come with some of the basic tools for deployment, including sheaths and balloons; however, a cadre of other items is required. The bare essentials are a stiff 0.035-inch × 300-cm exchange length wire and a diagnostic catheter. Unfortunately, most thoracic aneurysm stent-graft cases use much more equipment than initially anticipated. It is therefore important to have a variety of other interventional devices readily at hand. This requires a stockpile of items, including stiff and floppy wires, hydrophilic wires, selective catheters, and additional balloons and stents. The latter may be called upon to manage access vessel interventions for a pre-existing stenosis or iatrogenic injury and should include balloon-expandable stents, self-expanding stents, and covered stents.

Although the goal is to proceed with only a femoral puncture or cutdown, adjunctive surgical procedures are sometimes indicated that require additional surgical equipment. This may come in the form of a planned concomitant procedure, anticipated additional procedure, or emergent operation. Potential concomitant or additional procedures include carotid-subclavian transposition/bypass or a retroperitoneal incision to access more proximal arteries capable of accommodating the stent-graft delivery system. Although infrequent, emergent operations are sometimes needed to manage access vessel trauma (ie, rupture, dissection, thrombosis, or embolization), device failure, or inadvertent coverage of a critical vessel.7, 8, 9 The tools for these operations should be in the room and available.

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Staffing 

Anesthetic care 

Many endoluminal interventions can be done with either local anesthesia or minimal sedation and thus require little in the way of adjunctive support from anesthetists, nurses, or radiologic technicians. Endovascular treatment of TAAs may eventually evolve into a similar state, but for the time being, this is not feasible. A team approach is essential. It is recommended that these cases be performed under general anesthesia to facilitate easier blood pressure control, minimize patient movement, and allow for an unencumbered transition to a conduit if necessary. Anesthetic support may be needed if spinal drainage is to be incorporated as part of the treatment algorithm.10, 11 This includes placement of the drainage catheter as well as monitoring the transduced pressure and total volume removed during the case. In many centers, the anesthesia team also has the equipment and is responsible for obtaining and measuring the activated clotting time (ACT) after the administration of systemic heparin.

Technical support 

Any scrub assistants at the table should be facile at endovascular interventions as well as open surgical techniques. This includes prior working knowledge in preparing wires, catheters, sheaths, and the devices themselves. It is critical to remove all the air from these devices before introduction to minimize the risk of air embolization to end organs. An inexperienced assistant jeopardizes a successful procedure and should not be tolerated. Training can be gained either on site through formal in-service programs or off site at centers of excellence.

The last member of the team is the radiologic technician. This individual’s responsibility is highly dependent on the imaging equipment available. The more sophisticated the equipment (ie, fixed unit with tableside controls), the less involved he or she will be. Managing the power injector may be an additional responsibility for the technician, unless an injector with a sterile, handheld control is available to prepare and operate the device.

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Subspecialty overlap 

Thoracic stent-graft repair is analogous to many other therapies in medicine in that it is not exclusive to one particular specialty. The procedure has a number of technical components that dictate its inclusion in vascular surgery, cardiothoracic surgery, interventional radiology, and interventional cardiology. Although the former two may have a better understanding of the pathology, natural history, and indications for treatment, the latter two may be more skilled at the endoluminal techniques required to treat the patient. Much of this has changed in recent years with the introduction of stent-grafts for infrarenal aortic aneurysms and, as a result, quite a bit of subspecialty overlap exists, such that these groups often function independently. Although this is reasonable, my personal bias is to work together in a collaborative effort, so that each group’s particular skill may provide added benefit to the patient. Finances aside, this certainly requires a collegial approach and the avoidance of turf wars. Guidelines in clinical competencies and privileging, covered in a separate chapter, may help collaborative efforts; however, these are typically locally controlled.

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Referral base 

The final component of developing a successful endovascular TAA repair program is to establish a strong referral base. Success in this arena is dependent on demonstrating success with the new therapy and providing timely feedback to referring physicians. Careful patient selection is obviously important in achieving good results in the early phase of development. Such a program should also be able to provide standard open surgical options with comparable outcomes. Providing continuing medical education-sponsored events open to internists, cardiologists, radiologists, and vascular and cardiothoracic surgeons is an alternative means of presenting outcomes using both treatment paradigms. By providing traditional care options as well as cutting-edge technologic advancements, a dedicated group of physicians can grow into a respected, regional referral center.

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Conclusion 

Clinical trials support the early success of endoluminal exclusion of TAAs and have led to the availability of an approved device. Centers with a strong will to develop a well-rounded program to treat these difficult aneurysms can achieve success with a dedicated approach. Development of an endovascular TAA repair program requires state-of-the-art imaging systems, a stockpile of endovascular equipment, well-trained personnel, and a collegial environment. Although this can be an expensive and laborious endeavor, the end result is rewarded by improved patient recovery and outcomes.

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References 

  1. Makaroun MS , Dillavou ED , Kee ST , Sicard G , Chaikof E , Bavaria J , et al.   Endovascular treatment of thoracic aortic aneurysms (results of the phase II multicenter trial of the GORE TAG thoracic endoprosthesis) . J Vasc Surg . 2005;41:1–9
  2. Greenberg RK , O’Neill S , Walker E , Haddad F , Lyden SP , Svensson LG , et al.   Endovascular repair of thoracic aortic lesions with the Zenith TX1 and TX2 thoracic grafts (intermediate-term results) . J Vasc Surg . 2005;41:589–596
  3. Najibi S , Terramani TT , Weiss VJ , MacDonald JM , Lin PH , Redd DC , et al.   Endoluminal versus open treatment of descending thoracic aortic aneurysms . J Vasc Surg . 2002;36:732–737
  4. Zanchetta M , Rigatelli G , Pedon L , Zennaro M , Ronsivalle S , Maiolino P . IVUS guidance of thoracic and complex abdominal aortic aneurysm stent-graft repairs using an intracardiac echocardiography probe (preliminary report) . J Endovasc Ther . 2003;10:218–226
  5. Hansen CJ , Bui H , Donayre CE , Aziz I , Kim B , Kopchok G , et al.   Complications of endovascular repair of high-risk and emergent descending thoracic aortic aneurysms and dissections . J Vasc Surg . 2004;40:228–234
  6. Morasch MD , Kibbe MR , Evans ME , Meadows WS , Eskandari MK , Matsumura JS , et al.   Percutaneous repair of abdominal aortic aneurysm . J Vasc Surg . 2004;40:12–16
  7. Rehders TC , Petzsch M , Ince H , Kische S , Korber T , Koschyk DH , et al.   Intentional occlusion of the left subclavian artery during stent-graft implantation in the thoracic aorta (risk and relevance) . J Endovasc Ther . 2004;11:659–666
  8. MacDonald S , Byrne D , Rogers P , Moss JG , Edwards RD . Common iliac artery access during endovascular thoracic aortic repair facilitated by a transabdominal wall tunnel . J Endovasc Ther . 2001;8:135–138
  9. Yano OJ , Faries PL , Morrissey N , Teodorescu V , Hollier LH , Marin ML . Ancillary techniques to facilitate endovascular repair of aortic aneurysms . J Vasc Surg . 2001;34:69–75
  10. Ishimaru S , Kawaguchi S , Koizumi N , Obitsu Y , Ishikawa M . Preliminary report on prediction of spinal cord ischemia in endovascular stent graft repair of thoracic aortic aneurysm by retrievable stent graft . J Thorac Cardiovasc Surg . 1998;4:811–818
  11. Gravereaux EC , Faries PL , Burks JA , Latessa V , Spielvogel D , Hollier LH , et al.   Risk of spinal cord ischemia after endograft repair of thoracic aortic aneurysms . J Vasc Surg . 2001;34:997–1003

 Competition of interest: none.

PII: S0741-5214(05)01859-8

doi:10.1016/j.jvs.2005.10.044

Journal of Vascular Surgery
Volume 43, Issue 2, Supplement , Pages A3-A5, February 2006

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