Chapter 18. Recommended clinical competencies for initiating a program in endovascular repair of the thoracic aorta

Transcription

1 Chapter 18 Recommended clinical competencies for initiating a program in endovascular repair of the thoracic aorta Ross Milner, MD, Karthik Kasirajan, MD, and Elliot L. Chaikof, MD, PhD, Atlanta, Ga The continued expansion of endovascular technology has recently led to the availability of endovascular grafts for the treatment of a variety of acute and chronic diseases of the thoracic aorta. Early clinical trials have demonstrated that this technology represents a major advance in the field, with significant reductions in perioperative morbidity and mortality as compared with standard open surgical repair. 1,2 Nonetheless, because clinical experience with endovascular repair of the thoracic aorta remains limited, widespread introduction of endografts mandates their judicious application in a manner that maximizes safe and effective outcomes. As such, a minimum set of cognitive, technical, and clinical skills must be mastered by those who intend to use this technology, so that it is used in a manner commensurate with the best standards of clinical care (Tables I-III). The requisite fundamental knowledge base necessary to care for patients with aneurysmal disease of the thoracic aorta includes a comprehensive understanding of the risk factors, epidemiology, pathology, pathophysiology, natural history, clinical presentation, and therapeutic alternatives. Appropriate decision-making regarding indications, limitations, and complications of the procedure mandates a high level of skill in patient assessment and sound clinical judgment. Knowledge about angiographic equipment, as well as familiarity with the full range of sheaths, catheters, guidewires, stents, and endografts, is critical, as is expertise in a wide range of open vascular surgical procedures. The capacity to anticipate periprocedural and postprocedural issues with appropriate management of these with adjunctive therapies is also essential to optimize both shortand long-term outcomes. For example, use of adjunctive procedures before, during, or after device deployment is routine during the course of endovascular aortic repair (Tables IV-VI). Familiarity with many, if not all, of these From the Division of Vascular Surgery and Endovascular Therapy, Emory University School of Medicine. Competition of interest: none. Reprint requests: Ross Milner, MD, Department of Surgery, Division of Vascular Surgery and Endovascular Therapy, Emory University School of Medicine, 1364 Clifton Rd, Suite H-122, Atlanta, GA ( ross.milner@emoryhealthcare.org) /$32.00 Copyright 2006 by The Society for Vascular Surgery. doi: /j.jvs A procedures may dictate the difference between a successful outcome and treatment failure. In this document, a detailed outlined is provided of areas in which prerequisite technical experience is recommended, including abdominal endovascular aneurysm repair and related catheter and surgical skills, as well as associated cognitive and clinical skills that are necessary for optimal perioperative management of these complex patients. COGNITIVE SKILLS REQUIREMENTS Physicians performing endovascular repair must first possess a comprehensive knowledge base regarding thoracic aortic disease and its ramifications. They must understand the basic epidemiology, pathophysiology, natural history, diagnostic methods, and therapeutic alternatives. With evolving technology facilitating a growing application of endovascular repair to a diverse group of aortic pathologies, knowledge of acute and chronic manifestations of degenerative, congenital, traumatic, and mycotic processes is essential. However, it is of particular importance that the physician possess a detailed understanding of the epidemiology and pathophysiology of aneurysms of the thoracic aorta. The risk factors for rupture must be recognized and factored into decision-making regarding repair. The physician caring for patients with thoracic aortic disease should also be familiar with the various noninvasive imaging methods, including magnetic resonance and computed tomographic angiography. The indications for performance of arteriography and subsequent intervention should be clearly understood. Alternative open surgical therapies to endovascular repair must be appreciated and presented to patients during consultation. Data regarding success and the risk of open surgery and endovascular repair must be understood and communicated to patients when deciding on the optimal treatment strategy. Subsequently, the treating physician should be familiar with the role of postprocedure surveillance and the interpretation of imaging studies. TECHNICAL SKILLS REQUIREMENTS Ideally, the physician should be fully credentialed for peripheral interventions at his or her institution and actively performing a variety of endovascular procedures. The baseline

2 JOURNAL OF VASCULAR SURGERY Volume 43, Number A Milner, Kasirajan, and Chaikof 101A Table I. Cognitive skills requirements for endovascular thoracic aortic repair I. Pathophysiology of thoracic aortic disease Causes of atherosclerosis, aneurysm, dissection, coarctation, intramural hematoma, and traumatic rupture II. Clinical manifestations of thoracic aortic disease Knowledge of acute and chronic presentations of aortic aneurysm and dissection Knowledge of congenital, traumatic, and mycotic syndromes of the thoracic aorta Knowledge of manifestations of aortic ulcer and nonaneurysmal atherosclerosis III. Natural history of thoracic aortic disease IV. Associated pathology including arch vessel, abdominal aortic, and peripheral artery disease V. Diagnosis of thoracic aortic disease History and physical examination Noninvasive imaging including intravascular ultrasonography, MRA, CTA, and TEE VI. Angiographic anatomy Arch, thoracic, abdominal, visceral and iliac vessels Common anatomic variants VII. Knowledge of alternative treatment options for thoracic aortic disease and their results (immediate success, risks, and long-term outcome) Pharmacotherapy (eg, antihypertensive and antiplatelet agents) Traditional surgical approaches Endovascular treatment options VIII. Patient selection Indications and contraindications for interventions to prevent aneurysm rupture or to treat symptoms High-risk criteria for traditional surgical therapy High-risk criteria for endovascular intervention IX. Role of postprocedure follow-up and surveillance Knowledge and management of spinal ischemia and other peripheral or cerebrovascular ischemic syndromes Knowledge and management of endoleak, endograft migration, or device collapse Knowledge of postdeployment surveillance and clinical follow-up MRA, Magnetic resonance imaging; CTA, computed tomographic angiography; TEE, transesophageal echocardiography. Table II. Technical skills requirements for endovascular thoracic aortic repair I. Expertise with periprocedural anticoagulation and hypertension management II. Angiographic skills Vascular access skills Selection of guidewires, angiographic catheters, and sheaths Appropriate manipulation of guidewires and catheters Knowledge of normal angiographic anatomy and common variants, including assessment of aortic arch configuration as it affects intervention Familiarity with use of imaging equipment, including angulated views Familiarity with use of intravascular ultrasonography and transesophageal echocardiography III. Interventional skills Catheter, guidewire, and sheath placement Endograft positioning and deployment Peripheral and aortic balloon catheters Peripheral and aortic stent deployment Management of percutaneous vascular access sites, including sheath removal and closure device utilization IV. Open-surgical skills Femoral artery exposure Creation of iliac or aortic conduit, femoral-femoral, ileofemoral, visceral vessel debranching (eg, retrograde ileo to superior mesenteric artery/renal/hepatic bypass), carotid-carotid, or carotid-subclavian bypass Open thoracotomy and direct aortic repair, including use of associated adjuncts, such as atriofemoral or axillofemoral bypass V. Recognition and management of intraprocedural complications Hemorrhage Thrombosis Dissection Perforation Endoleak Stroke Inadvertent branch vessel occlusion or stenosis Device malposition skill set must include a knowledge of appropriate use of imaging equipment, how to obtain digital and subtracted images, and how to use angulated views to optimally examine the thoracic aorta and associated branch vessels. In addition, the physician should have an understanding of the proper use of contrast agents. Finally, expertise in the use of adjunct equipment and techniques, such as peripheral angioplasty or stenting, as well as intravascular ultrasonography, is required.

3 102A Milner, Kasirajan, and Chaikof JOURNAL OF VASCULAR SURGERY February Supplement 2006 Table III. Clinical skills requirements for endovascular thoracic aortic repair I. Determine the patient s risk/benefit for the procedure II. Preoperative management Adjust medications Counsel patient and family III. Perioperative responsibilities Admit patients and write orders Obtain informed consent for procedures Provide preprocedure and postprocedure hospital care, including evaluation of neurologic, hemodynamic, and peripheral vascular status IV. Coordinate surveillance and clinical follow-up Table IV. Endovascular thoracic aortic repair I. Management of concomitant iliac/renal/visceral/arch vessel occlusive disease Balloon dilatation Stent deployment II. Management of collateral arteries originating within the aneurysm Embolization of visceral arteries (eg, celiac) or the subclavian artery III. Management of arterial branches that will be deliberately rendered ischemic Carotid-subclavian transposition or bypass Carotid-carotid bypass or ascending aorta to innominate artery or carotid artery bypass Visceral vessel debranching (eg, retrograde revascularization of renal, superior mesenteric artery, or hepatic artery by a bypass from the iliac artery) Thoracic angiography. Competence in the performance and interpretation of diagnostic angiography of the entire aorta and associated branch vessels must be achieved. Selective catheterization studies of arch vessels, as well as visceral or other peripheral vessels, are often not indicated for thoracic endograft procedures; however, knowledge of how to safely perform these studies is important for the cases in which it is appropriate. Performance of angiography requires that the operator recognize all pathology that might have a bearing on the outcome of a procedure or ongoing patient care. For example, the aortic arch can be severely diseased in this patient population, thus increasing the risk of both stroke and paraplegia. 1,3 Stroke is a significant risk in patients in whom multiple manipulations of stiff wires and large devices are anticipated and should be included in a complete discussion of periprocedural adverse events. As part of aortic arch evaluation, it is also important to investigate the status of both vertebral arteries. It is necessary, at times, to cover the left subclavian artery to obtain an appropriate proximal attachment site; this can usually be done safely when both vertebral arteries are patent. If this is not the case, or if the left internal mammary artery has been used for coronary revascularization, an initial carotid-subclavian bypass is required. Likewise, angiographic confirmation of a suitable distal landing zone above the celiac axis is required for successful exclusion of a thoracic aneurysm, unless planned visceral debranching provides an alternate option. Table V. Intraoperative adjunctive maneuvers associated with endovascular thoracic aortic repair A. Planned procedures I. Management of access site Modified access sites Sheath introduction to iliac artery or abdominal aorta via prosthetic conduit or by direct open puncture Sheath introduction to brachial artery for assistance with associated intraoperative adjunctive maneuvers (eg, subclavian artery embolization) Repair of femoral aneurysm at access site by interposition bypass graft Percutaneous arterial access site closure systems II. Management of iliac arterial tortuosity Transfemoral pull-down maneuver to straighten the iliac artery by retrograde traction Direct or indirect manual deformation of artery Brachiofemoral wire III. Management of occlusive disease of the iliac arteries Balloon angioplasty and/or placement of a covered stent Sizing with an arterial dilator B. Unplanned procedures I. Management of perforation of iliac artery or abdominal or thoracic aorta Endovascular repair Direct repair or bypass graft placement Conversion to open repair of thoracic aorta II. Management of obstructed blood flow of a peripheral, visceral, or arch vessel Angioplasty and stent placement with or without associated adjunctive maneuvers (eg, thrombolysis or thrombectomy with an AngioJet catheter) Open thrombectomy, endarterectomy, or bypass grafting Conversion to open repair III. Management of endoleak Balloon dilation with or without stenting or deployment of an additional endograft Embolization options Thoracic intervention. Thoracic intervention skills include knowledge of proper selection and placement of large sheaths and catheters in often tortuous vessels; safe manipulation of guidewires; proper selection, delivery, and accurate deployment of stents and endografts; and correct choice and use of balloons, including an appreciation of appropriate balloon size, inflation pressure, and inflation time. Detailed knowledge of how to avoid complications and to treat them if they should occur is critical. The physician must be capable of recognizing and understanding the angiographic findings seen during thoracic endografting, including dissection and intimal disruption. Similarly, the clinician must know how to avoid and treat arterial dissection, thrombosis, and vessel perforation, as well as options for correcting a malpositioned device. PREREQUISITE TRAINING IN ENDOVASCULAR AND OPEN SURGICAL SKILLS Published results demonstrate improved patient outcomes with increasing physician experience in the endovascular repair of aortic aneurysms. 4 This emphasizes the presence of a learning curve and the need for careful and

4 JOURNAL OF VASCULAR SURGERY Volume 43, Number A Milner, Kasirajan, and Chaikof 103A Table VI. Postoperative adjunctive maneuvers associated with endovascular thoracic aortic repair I. Management of wound complications at access site Evacuation of hematoma Operation for lymph fistula or lymphocele Operative or endovascular repair of false aneurysm II. Management of delayed peripheral vascular, visceral vessel, or cerebrovascular ischemia Angioplasty and stent/endograft placement with or without associated adjunctive percutaneous maneuvers (eg, thrombolysis or thrombectomy with an AngioJet catheter) Open thrombectomy, endarterectomy, or bypass grafting III. Management of endoleak Balloon dilation with or without stenting or deployment of an additional endograft Embolization options Open or videoscopic external banding procedures IV. Management of device migration, collapse, component dislocation, or disruption Deployment of an additional endograft V. Management of secondary aortic dissection or aortic rupture Deployment of an additional endograft Table VII. Minimum technical experience required before conducting endovascular thoracic aortic repair Variable Volume Minimum endovascular case volume Diagnostic angiograms 100 Selective catheterizations 50 (10 of arch vessels) Intravascular ultrasonography 10 Peripheral noncoronary interventions (eg, angioplasty/stenting) 50 Endovascular abdominal aortic repair 25 Minimum vascular surgical case volume Major abdominal vascular procedures 30 Peripheral vascular procedures 45 Complex aortic reconstruction 10 Open thoracotomy 10 Completion of industry-sponsored device certification Supervised thoracic film review, device selection, and treatment planning 5 Thoracic case observation/supervision 5 thorough training and preparation in both endovascular and vascular surgical techniques (Table VII). Endovascular training in diagnostic angiography and peripheral interventions. It is evident that experience in basic endovascular skills is necessary for endografting. A treating physician must have training in percutaneous femoral and brachial arterial access techniques and must have a thorough knowledge of differences among sheaths, wires, catheters, balloons, and devices, including balloon and self-expanding stents, covered stents, and endografts. This knowledge is just as important for the safe deployment of a device as it is for the treatment of possible complications. Before pursuing thoracic endografting, the physician should have performed at least 100 diagnostic arteriograms and have experience with a minimum of 50 procedures in which a peripheral (nonaortic) intervention was performed. Diagnostic procedures should have included angiography of the entire thoracic and abdominal aorta with selective catheterizations of associated arch, visceral, and peripheral vessels in at least half of these cases. Expertise with intravascular ultrasonography is also necessary. Intravascular ultrasonography is exceptionally useful for accurately sizing the aorta and iliac vessels and defining intraluminal thrombus and dissection flaps and, as a consequence, has an important role in assessing access vessels, identifying appropriate landing zones, and selecting endovascular devices or stents of the correct dimension. 5 Training in peripheral interventions, in particular, should include experience with angioplasty and stenting, which may be required for the management of iliac vessels during the course of attaining access for thoracic endovascular repair or after endovascular grafting. Access for thoracic endografting is limited by iliac artery size, tortuosity, and calcification: a small, calcified, and angulated external iliac artery often precludes transfemoral access. However, focal occlusive disease may be amenable to preliminary angioplasty to facilitate sheath access for an endovascular graft. Bare metal stents and covered stents are not routinely used to facilitate initial access but are often required for treatment of iliac dissections or arterial perforations caused when the delivery catheter or sheath is introduced or removed. It bears emphasis that the treating physician must demonstrate that iliac arteries are intact before the conclusion of the procedure. In short, the ability to diagnose and treat iliac occlusive disease, as well as to identify and manage iatrogenic iliac injuries, including proper stent selection, is crucial for the safe treatment of this patient population. Training in endovascular repair of abdominal aortic aneurysms. Experience with abdominal aortic endografting comprises a mandatory skill set for any physician planning on treating thoracic aortic aneurysmal disease. This includes a comprehensive understanding of and demonstrated expertise in preoperative planning, device selection with measurement and assessment of landing zones, femoral artery exposure, placement of large sheaths, and capacity to precisely deploy endografts with preservation of branch vessels. Training in endovascular wire, catheter, and balloon skills is crucial because of the tortuous nature of the aorta and iliac vessels, as well as the frequent presence of complex aortic arch anatomy. Experience in the planning, sizing, and performing of 25 endovascular abdominal aortic aneurysm repairs is recommended before use of thoracic aortic endografts. The ability to appreciate the degree of iliac tortuosity and calcification and the effect of these factors on sheath access is particularly important to safe deployment of an aortic endograft. For example, iatrogenic disruption of an iliac artery can be a life-threatening event if not handled expeditiously, and the use of an iliac access conduit as a means of avoiding this complication is important when the iliac anatomy

5 104A Milner, Kasirajan, and Chaikof JOURNAL OF VASCULAR SURGERY February Supplement 2006 seems complex. The delivery systems for the abdominal devices are smaller and more flexible than for the thoracic devices but are considerably larger than the sheaths normally used for percutaneous interventions. Thus, clinical experience with abdominal endografts provides the best opportunity to become sufficiently familiar with the introduction of, passage of, and ability to track large devices and associated techniques to minimize the risk of significant blood loss or catastrophic arterial injury. Specifically, experience gained in correlative preoperative image analysis and subsequent device deployment enhances expertise in access site selection and optimal use of adjunctive open or endovascular procedures to gain access to the infrarenal aorta. Moreover, demonstrated expertise in measuring aortic dimensions, as well as gauging the angulation and tortuosity of the aortoiliac system, provides the clinician with a cognitive framework for appropriate device selection in the thoracic aorta. Placing an endograft necessitates the preservation of critical branch vessels, whether the disease site is the abdominal or thoracic aorta. For example, precise deployment of infrarenal devices is required to avoid inadvertent occlusion of the renal or pelvic blood supply. These tasks in the abdominal aorta correlate with preservation of the arch vessels and the celiac axis during thoracic endografting, but the latter are often much more complex. Tortuous arch anatomy, aneurysmal disease that requires covering the left subclavian artery, and an angulated distal thoracic aorta at the level of the celiac axis are all quite common. Training in open vascular surgical skills. Open vascular surgical skills remain a critical component of endovascular repair of the thoracic aorta. Facility in this skill set mandates training in techniques that are common to general vascular surgery, including bypass grafting and endarterectomy, as well as experience in open surgical repair of the thoracic aorta. Vascular surgical training with prior performance of 100 major open vascular procedures, including 25 aortic reconstructions and experience in performing at least 10 thoracotomies, is recommended. The most common open vascular surgical procedure in performance of thoracic endovascular aortic repair is common femoral artery exposure. In certain circumstances, exposure of the superficial femoral and profunda femoris arteries may be required when a diseased common femoral artery is encountered. Local endarterectomy may be necessary, or if the artery is severely damaged by the introducer sheath, reconstruction with an interposition graft may be required. Experience gained with abdominal devices demonstrates that the femoral artery, along with the external iliac system, can be damaged, disrupted, or completely avulsed during endovascular aneurysm repair. Until the profile of endograft delivery sheaths is significantly reduced, the implanting physician will need to be able to recognize and reconstruct a local or remote injury. Groin wound complications, including hematoma, pseudoaneurysm, and lymphocele, are infrequent with endograft deployment, but facility in the management of these complications is a necessary skill. Retroperitoneal exposure of the common iliac artery is an open surgical technique in which expertise is also required. 6 Currently the external iliac artery must be at least 7 mm in diameter for passage of a delivery catheter or sheath and preferably 8 mm or larger. Retroperitoneal exposure of the left common iliac artery or the distal abdominal aorta provides a convenient secondary access site for placement of a conduit. In the Thoracic Aortic Graft multicenter trial sponsored by W. L. Gore (Flagstaff, Ariz), 17% of patients required an elective conduit for device placement. 1 Thus, knowledge of retroperitoneal exposure is mandatory to facilitate surgical treatment for iliac perforations that cannot be managed by covered stents. Experience in performing peripheral bypass graft procedures including femoral-femoral, ileofemoral, visceral vessel debranching (eg, iliac to superior mesenteric, renal, or hepatic artery bypass), aortoinnominate, carotid-carotid, and carotid-subclavian bypass is necessary, because it may be required to perform a peripheral bypass before or after endovascular repair for management of branch vessels that have been occluded either intentionally or inadvertently. It is exceptionally rare to rupture the thoracic aorta during device placement. However, should this occur, conversion to open surgical repair may be necessary if an endograft cannot be placed expeditiously. Initial control with an aortic occlusion balloon can stabilize until appropriate surgical exposure is obtained. The capacity to perform a thoracotomy, obtain proximal and distal control, and directly repair the aorta with or without an adjunctive axillofemoral or partial left atrial-to-femoral bypass should be part of a physician s training, if not current practice. Device-specific training. Successful completion of an industry-sponsored certification course may be required to ensure familiarization with specific equipment as approved by the Food and Drug Administration. Intraoperative proctoring by an experienced physician should be conducted on a minimum of five cases if the operator has not had experience with endovascular repair of the thoracic aorta. Although industry sponsored training may assist the physician in completing supervised film review and case observation, completion of an industry-sponsored certification course does not confer adequate qualifications for performance of thoracic endovascular repair as a primary treating physician. CLINICAL SKILLS REQUIREMENTS The clinical component required to be competent in endovascular management of patients with thoracic aneurysms assumes that the physician is able to assess and manage the patient before, during, and after the procedure, as well as in long-term follow-up. Specific clinical skills include the ability to measure risks and benefits, to inform patients and families of the therapeutic alternatives, and to properly care for patients during and after the procedure. The physician must be capable of identifying and managing complications that might be encountered after initial treatment. For example, paraplegia is a known complication of thoracic aortic reconstruction. Although it is much more common in the open setting, the risk of paraplegia remains

6 JOURNAL OF VASCULAR SURGERY Volume 43, Number A Milner, Kasirajan, and Chaikof 105A a concern even for those treated with an endograft. 2,7,8 A preoperative lumbar drain is usually reserved for patients who have had a prior abdominal aortic graft, but it may also be placed for postoperative salvage if paraplegia develops. It is mandatory that hospital staff be capable of managing a lumbar drain. Finally, the physician must be involved in patient follow-up, including surveillance for endoleak, aneurysm expansion, device migration, and other problems. CONCLUSIONS Physicians with diverse backgrounds and varying levels of expertise will seek training in endovascular techniques for repair of thoracic aneurysms. Training requirements must be tailored to the particular needs of the individual seeking training. However, endovascular repair requires proficiency in interventional and open vascular surgical techniques, equipment, and clinical management skills, which differ significantly from those used in traditional open surgical treatment of the thoracic aorta. Moreover, considerable differences exist in the endovascular management of the abdominal and thoracic aorta. Thus, physicians caring for patients who display thoracic aortic pathology with endovascular techniques must be competent in the cognitive, clinical, and technical skills that are necessary to achieve an optimal outcome. 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: 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: Chiesa R, Melissano G, Marrocco-Trischitta MM, Civilini E, Setacci F. Spinal cord ischemia after elective stent-graft repair of the thoracic aorta. J Vasc Surg 2005;42: Forbes TL, DeRose G, Kribs SW, Harris KA. Cumulative sum failure analysis of the learning curve with endovascular abdominal aortic aneurysm repair. J Vasc Surg 2004;39: Lee JT, White RA. Basics of intravascular ultrasound: an essential tool for the endovascular surgeon. Semin Vasc Surg 2004;17: Lee WA, Berceli SA, Huber TS, Ozaki CK, Flynn TC, Seeger JM. Morbidity with retroperitoneal procedures during endovascular abdominal aortic aneurysm repair. J Vasc Surg 2003;38: Najibi S, Terramani TT, Weiss VJ, Mac Donald MJ, Lin PH, Redd DC, et al. Endoluminal versus open treatment of descending thoracic aortic aneurysms. J Vasc Surg 2002;36: Leurs LJ, Bell R, Degrieck Y, Thomas S, Hobo R, Lundbom J, et al. Endovascular treatment of thoracic aortic diseases: combined experience from the EUROSTAR and United Kingdom Thoracic Endograft registries. J Vasc Surg 2004;40: Submitted Oct 15, 2005; accepted Oct 27, 2005.