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Essentials of endovascular surgery training: how to get started in carotid stenting
Essentials of Endovascular Surgery Training: How to Get Started in Carotid Stenting By Kim J. Hodgson Although early on vascular surgeons rebuked the concept that carotid stenting could stand up against the gold standard of carotid endarterectomy, this minimally invasive treatment for carotid bifurcation disease has been shown to have surprisingly low rates of periprocedural complications and is clearly favored by patients, for whom avoidance of surgery reigns paramount. Unfortunately, reluctance to embrace this and other emerging endovascular technologies, as well as a variety of other factors to be discussed, has left vascular surgeons poorly positioned to participate in the delivery of these therapies to their patients. With estimates of up to 75% of carotid stenoses being suitable for treatment by this new modality, and with carotid endarterectomy being the most commonly performed vascular operation in the United States today, this is a significant problem for our specialty and one badly in need of a solution. An understanding of the myriad of underlying interrelated problems helps to provide insight into possible solutions. © 2003 Elsevier Inc. All rights reserved. EVOLUTION VERSUS REVOLUTION: ACQUIRING THE REQUISITE BASIC SKILLS
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HILE A HANDFUL of vascular surgeons have been advocating and practicing comprehensive endovascular therapy for over a decade1 and have, therefore, evolved their technical skill set with the field, most vascular surgeons only recently entered the endovascular arena, prompted only by the advent of the aortic endografting revolution. Though the limited and relatively crude skill set required to insert an endograft in an aortic aneurysm allowed vascular surgeons to revolutionize their treatment of this condition, the acquired skills provide only meager preparation for the technically demanding procedure of carotid stenting. Additionally, most vascular surgeons have limited their involvement in aortic endografting to the endograft insertion itself, deferring ancillary procedures such as diagnostic angiography, coil embolization, endoleak management, and the endovascular treatment of concomitant disease to their radiologists. The techniques, instrumentation, and anatomical demands of these ancillary procedures more closely mirror those required for carotid stenting, and therein lies the first step a vascular surgeon interested in carotid stenting should consider taking: attainment of comprehen-
From Southern Illinois University, Springfield, IL. Address correspondence to Kim J. Hodgson, MD, Southern Illinois University, P.O. Box 19638, Springfield, IL 62794-9638. © 2003 Elsevier Inc. All rights reserved. 0895-7967/03/1604-0003$30.00/0 doi:10.1053/j.semvascsurg.2003.08.003 262
sive catheter and guidewire skills and development of a broad-spectrum endovascular practice so that they can evolve into carotid stenters. The risks to the patient of a suboptimal carotid angioplasty are simply too great for adoption of this procedure to be a revolution in a vascular surgeon’s practice. Evolving one’s practice is clearly within the reach of most vascular surgeons, as they continue to control the majority of patients with vascular disease, though they typically underutilize these opportunities for their own endovascular growth. While every carotid stent procedure begins with obtaining sheath access to the common carotid artery, most vascular surgeons have no experience even catheterizing these vessels with diagnostic catheters; the most basic step in the procedure beyond obtaining percutaneous femoral access. The catheters and techniques used for such catheterizations are significantly different from those used for aortic endografting, but well within the technical abilities of vascular surgeons to learn. However, opportunities to learn diagnostic carotid angiography have diminished over the past decade as numerous publications documented the accuracy of colorflow carotid duplex scanning and advocated performance of carotid endarterectomy without angiography. Carotid stenting, however, has made it an entirely new ballgame. No longer is the carotid bifurcation the only area of interest if carotid stenting is to be considered as a therapeutic option for a patient. Evaluation of the arch for access issues, and the determination of lesion characteristics, anatomic variations, and confounding secondary lesions all now mandate performance of
Seminars in Vascular Surgery, Vol 16, No 4 (December), 2003: pp 262-269
ESSENTIALS OF ENDOVASCULAR SURGERY TRAINING
a diagnostic carotid angiogram prior to, or at the time of, carotid angioplasty. While carotid angioplasty threatens to take the treatment of carotid bifurcation disease away from vascular surgeons, it also provides an opportunity for those suitably dedicated and committed endovascular surgeons to expand both their diagnostic and therapeutic armamentariums. So, with consideration for carotid angioplasty in mind, performance of diagnostic carotid angiography becomes a justifiable procedure in the evaluation of a patient with carotid bifurcation disease. Furthermore, because the catheters and skills needed to selectively catheterize the common carotid arteries constitute the most difficult aspects of the angioplasty procedure, adopting a routine of obtaining diagnostic angiography and performing it yourself helps refine those skills and prepare you for subsequent angioplasty procedures. Considered from the viewpoint of a credentials committee member evaluating an application to perform carotid angioplasty, it would be much easier to justify granting privileges to treat a vessel to someone who already had experience catheterizing and evaluating that region than to a complete novice in cerebrovascular angiography. Lastly, using preangioplasty angiographic evaluation as your justification to perform a diagnostic study opens the door for you to perform other “planning” endovascular procedures and to argue for access to dedicated angiographic facilities suitable for percutaneous diagnostic angiography. Overall, the benefits of incorporating diagnostic carotid angiography into your practice are multiple and are a requisite initial step towards getting started in carotid stenting. CAROTID CREDENTIALING: WHAT’S IN A BUNDLE?
At this time, the prevailing endovascular credentialing recommendations are those of the Society for Vascular Surgery (SVS)2 and the American Heart Association (AHA),3 neither of which in any way distinguish carotid angiography or angioplasty from analogous procedures in other peripheral vascular territories, or call for separate credentialing of this or any other territory. Some hospital credentials committees have taken this to indicate that carotid procedures are included in the endovascular “bundles” of these documents, while others have established restrictive covenants or supplemental requirements, such as the adoption of those
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mandated by the U.S. Food and Drug Administration (FDA) for aortic endografting. In this author’s experience, the “unbundlers” for carotid angioplasty are usually motivated by turf or political issues, as the requisite technical skill set needed to safely perform this procedure is no greater than that for renal angioplasty, a vessel comfortably within the bundle. Nonetheless, each physician seeking credentials for carotid angioplasty will need to negotiate the maze of political and credentialing issues specific to their hospital with the knowledge that, at this point, there are numerous examples of vascular surgeons performing this procedure across the country, so it should not be considered a radical departure from accepted practice. And, absent any credentialing standards specific to carotid angioplasty, it should be sufficient to be credentialed under either the SVS or AHA pathways and successfully argue that carotid bifurcation disease is part of your bundle of skills and well-within your logical domain. Ideally, these privileges include access to a dedicated angiographic facility for optimal imaging. It is beyond the scope of this discussion to address legal or political issues related to credentialing for carotid angioplasty, as these are unique to every medical institution during this limbo period where no national standard exists. However, the much-anticipated approval of a carotid angioplasty system expected within the year will likely establish such a standard through the training program requirements adopted with the FDA. Opportunities for training and use of that stent-protection system will also become available, though they may be limited and could take several years to include all vascular surgeons. In the meanwhile, it is relevant to consider some of the nuances of carotid angioplasty that uniquely impact on a hospital’s willingness to credential and permit carotid angioplasty procedures to be performed and, therefore, the vascular surgeon’s ability to adopt this therapy. ALL DRESSED UP AND NOWHERE TO GO
It is often erroneously assumed that credentialing by a hospital is tantamount to being granted permission to perform a procedure in that hospital. In fact, while credentialing does reflect the judgment of the credentials committee that a physician has met a requisite level of training needed to safely perform a procedure, the hospital may still
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prevent the physician from doing so, even if “credentialed” to do so. Most often this is due to restrictive contracts that grant exclusive rights to perform certain procedures to certain physicians (a perfectly legal situation), or for a variety of other reasons. For carotid angioplasty, a significant “other” reason, is that the procedure is under national noncoverage status from the Center for Medicare and Medicaid Services (CMS). What this means is that, with the exception of patients being treated in a U.S. FDA Investigational Device Exemption (IDE) trial, none of the expenses associated with the carotid angioplasty procedure are reimbursable to either the physician or the hospital. In fact, complications directly arising from a procedure gone bad may also not be covered and could represent huge losses for a hospital. Therefore, the prudent hospital CEO is going to have to carefully weigh the costs of offering this therapy outside of an FDA clinical trial against whatever returns can be expected through marketing the procedure or actually reducing costs in certain truly high-risk patients. The effect of the national noncoverage policy on the ability of vascular surgeons to participate in the carotid angioplasty revolution has been profound. Even vascular surgeons with impeccable skills and reputations have been excluded from this area by virtue of nonparticipation in clinical trials and the national noncoverage policy. The evolution of the carotid angioplasty procedure itself has provided both opportunities and roadblocks to participation. Early on, before embolic protection devices, carotid angioplasty was essentially little different from renal angioplasty; an off-label use of an otherwise approved product, a stent. While compensation may or may not have been occurring, the stents and related equipment were readily available and usually separately billable by the hospital. Consequently, the general decision by vascular surgeons to show restraint at this stage gained us the label of “nonenthusiasts” for the technology. This ultimately hindered our participation in the subsequent clinical trials, into which embolic protection, though of unproven benefit, was incorporated and became the new standard of care. As the clinical trials evolved to include the use of embolic protection devices, however, it became medically and politically difficult to perform carotid angioplasty without embolic protection (EP), yet EP was only available within a clinical trial, few of which
KIM J. HODGSON
included surgeons. This is but one of the ironies of carotid angioplasty for vascular surgeons. WAS IT SOMETHING I SAID?
Beyond failing to adopt and endorse the procedure, many well-known vascular surgeons publicly sniped at the evolving technology and results, an attitude that was erroneously interpreted by industry to indicate widespread negativism by vascular surgeons towards the procedure. While this misperception undoubtedly cost us opportunities for early participation in carotid angioplasty through the clinical trial pathway, by far the greater impediment has been that of industry’s research and development structure. The first wave of the technological endovascular revolution, development of the aortic endograft, was led by companies with close allegiance to vascular surgeons who utilized those relationships throughout their research and development of the products. Unfortunately, those relationships did not translate into widespread involvement in research and development and clinical investigation of subsequent carotid stent systems. In fact, the carotid angioplasty revolution has been dominated by cardiologists, largely through their relationship with the cardiology device industry. While many vascular surgeons have felt excluded, this primarily reflects the business reality that carotid stent development was typically assigned to cardiology divisions within the industry, and those people’s preexisting relationships were primarily with cardiologists. Nonetheless, the overall effect has been to minimize the involvement of vascular surgeons in the entire field of carotid angioplasty, because without trial participation there is no reimbursement to make the procedure economically viable and, until recently, no access to cerebral protection. COULD IT GET ANY MORE UNFAIR?
So, we have a procedure that many vascular surgeons will have to struggle for credentials to perform, which neither the surgeon nor the hospital will get paid for, and which may have to utilize off-label first-generation embolic protection, if any at all. What’s to want for? The solution to all of the issues would appear to be to get into a clinical trial, a wedge often used to pry open credentialing doors, and one that clearly resolves the issues of reimbursement and contemporary cerebral protection. While the industry sponsored FDA IDE trials
ESSENTIALS OF ENDOVASCULAR SURGERY TRAINING
are largely closed to new participation and were always biased towards cardiology anyway, new trials will emerge and the CREST and CARESS trials remain opportunities for vascular surgeons to participate in a clinical trial, and by which to resolve most of the critical issues. But even this avenue is clogged with roadblocks. In order to be considered for CREST or CARESS you have to be able to document satisfactory success in 20 carotid angioplasty cases. Those would be 20 angioplasty cases you had to get your hospital to let you perform gratis and with first-generation (at best) cerebral protection. Once again, the profound impact of the national noncoverage policy, this time potentiated by the clinical trial requirement of prior angioplasty experience. You cannot get into a trial without carotid angioplasty experience and you cannot get carotid angioplasty experience without getting into a trial; if not because of hospital budgetary restraints then because of a commitment to contemporary embolic protection. The rationale for this requirement escapes logic when one considers that these trials have built-in “run-in” phases of up to 20 patients prior to allowing randomization, specifically structured to negate any learning curve issues. Thus, the need for pre– run-in cases has, in this author’s opinion, been more about exclusion of vascular surgeons than bona fide policy. Even if not so intended, it has undeniably resulted in the exclusion from clinical trials of many well-qualified vascular surgeons. MAKING THE BEST OF A BAD SITUATION
The recent FDA approval of the PercuSurge antiembolization system for coronary vein graft dilatation now provides access to an off-label cerebral protection system, albeit without solving the compensation issue. Nonetheless, it does provide an option for those truly high-risk patients who do not qualify for any available trial or are being treated in institutions not participating in such trials, to receive this mode of therapy today. Furthermore, outside of a clinical trial this is probably the only mechanism for vascular surgeons to begin to offer carotid angioplasty and stenting (CAS) to their patients. It is this author’s opinion that there truly are identifiable classes of patients with carotid bifurcation disease who are at higher, though perhaps not prohibitive risk for surgery, for whom CAS is a reasonable option to offer. Examples include restenosis after endarterectomy, a history
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of radical neck dissection or radiation therapy, or high cervical lesions beyond safe surgical exposure. In such cases the vascular surgeon can reasonably argue that, noncoverage policy not withstanding, CAS is the preferred and recommended therapy for this patient. Assuming both the surgeon and hospital are willing to go uncompensated, the procedure would be reasonable. Whether or not a vascular surgeon undertakes the procedure himself or refers the patient to someone else depends on his level of preparation for performing one of the more complex of the endovascular therapies. Assuming the endovascular surgeon is otherwise broadly experienced and possessed of advanced catheter and guidewire skills, evolving into CAS is essentially a matter of learning judgment about case selection and the specific “sequencing” of the procedure rather than specific new technical skills. Sequencing, referring to the choreographed performance of a number of technical steps, can be learned using either in vitro models or animal labs, though clearly both of these models poorly represent human disease and anatomy. Somewhat more authentic training can be obtained by using the PercuSurge device during renal angioplasty procedures where it may also be of benefit and clearly mimics CAS better than other discussed models. A new training modality on the horizon, to be discussed in more detail to follow, is that of computer-simulated training procedures. While clearly these systems provide training in sequencing, their cost is prohibitive if that is all they offer. Judgment is by far the more difficult need to address, as only a handful of operators have significant experience to share. Live-case demonstrations and problem-solving symposia at vascular surgical educational meetings can contribute significantly to one’s understanding of the problematic nuances of the procedure and are highly recommended. While in far from overwhelming numbers, physicians experienced in CAS who are willing to entertain observers and share their knowledge of the procedure, review cases, and perhaps allow hands-on participation are emerging, both in the United States and abroad. Many of them are collaborating closely with industry to aid in training the new workforce once CAS receives its anticipated FDA approval. It is fully anticipated that the training standard adopted at the time of FDA approval will set the standard nationwide for CAS credentialing, not only with that specific de-
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KIM J. HODGSON
Fig 1. Arch aortogram showing desirable origins of the brachiocephalic vessels high on the arch. Significant stenosis in the innominate artery complicates access to the right common carotid artery and will likely need to be dilated itself. Access to the left common carotid artery is ideal.
vice, but for the procedure itself, even if done using “off-label” devices. Until that standard is set and adopted by individual credentials committees, however, an experienced operator who devotes sufficient time to learning the sequencing of the system in use and proper case selection would be considered adequately prepared to embark on CAS. It goes without saying that early case selection is of particular importance in this contentious area. Several reasonable indications have already been discussed, but technical considerations are also in order. The specific deployment steps applicable to each CAS stent-protection system are variable, frequently changing, and beyond the scope of this article. However, awareness of anatomical issues that may complicate CAS is mandatory for optimal outcomes. Obtaining sheath access to the common carotid artery is the first major component of the CAS procedure and is easiest to accomplish safely in arches relatively free of atheromatous plaque and with high origins of the brachiocephalic vessels off of the top of the arch (Fig 1). Such anatomy minimizes access vessel tortuosity, facilitating sheath placement with the least amount of trauma and need for distal guidewire support. A thorough evaluation of the arch and proximal brachioce-
phalic vessels is in order to ensure that any significant occlusive disease is recognized and considered before deciding whether to treat this first and then perform CAS, perform CAS through the untreated disease, or abandon the CAS procedure altogether. Bovine arches (Fig 2), where the left common carotid artery arises from the innominate artery, can add an additional level of complexity to accessing the left side, the degree of which is variable between patients. Anatomic issues specific to the carotid bifurcation and internal carotid artery (ICA) can also significantly impact the safety of the procedure. Particularly troublesome are deeply ulcerated, irregular, and calcified lesions. Furthermore, lesions in arteries with significant tortuosity within several centimeters of the distal extent of the lesion to be stented (Fig 3) or at the origin of the ICA can also cause challenges. In the former case, deployment of an antiembolic protection device may be problematic or downright impossible, potentially elevating the risk of the procedure done with protection or mandating either unprotected CAS or a carotid endarterectomy. In the latter circumstances, smooth device tracking may be an issue, with a tendency for the device to plow across the surface of the plaque. This may also be a concern when
ESSENTIALS OF ENDOVASCULAR SURGERY TRAINING
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Fig 2. Bovine arch configuration complicating access to the left common carotid artery. Vessel origins high on the arch are otherwise ideal.
crossing critically tight stenoses, though device profile is constantly being downsized, and many operators routinely predilate the lesions after deployment of the protection device but before passage of the stent delivery system. Overall, the ideal anatomy is a patient with a high origin of the common carotid artery, off of an arch free of atheromatous disease, with a smooth focal subcritical stenosis in an ICA that originates from the carotid bulb without abrupt angulation and maintains a straight course well beyond the lesion to be treated (Fig 4). THE MORNING AFTER
Based on the reported 30-day data of the SAPPHIRE trial,4 FDA approval of a CAS system is anticipated within the next 12 months. Vascular surgeons would be mistaken, however, to think that they will then have ready access to the device to utilize liberally in their practices and receive compensation for. Firstly, the “roll-out” of the device is likely to be more controlled than with aortic endografts, reflecting lessons learned from that new device introduction and training program. Consequently, opportunities to participate in the FDA-mandated training program for CAS will be limited, and until such training is received, product
cannot be sold. Furthermore, vascular surgeons will be competing with two other specialties, interventional radiology and cardiology, for available training slots. How rigorous the mandated training is will also determine the availability of training opportunities. It is likely that there will be a requirement for actual human hands-on cases as the primary operator under supervision before the procedure can be performed independently. The number of required cases and whether they can be done at one’s home institution on one’s own patients or will require one to venture to another institution will both impact heavily on the number of opportunities to fulfill the training requirements. In the case where a new locale is required, outside credentialing and possibly an additional medical license will undoubtedly slow and limit this training pathway. While certainly desirable, successful completion of FDA-mandated CAS training may not actually significantly change the nature of your carotid practice for two reasons. First, there is reason to believe that CMS is planning to adopt measures to ensure that payment for CAS is only provided when performed in patients with the specific device labeling indications, essentially “high-risk” patients only. While the qualifying indications may
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KIM J. HODGSON
Fig 3. A loop in the ICA just distal to the lesion to be dilated precludes utilization of most antiembolic filters, which require a straight segment of ICA beyond the lesion.
be loose and the enforceability impractical, the message will undoubtedly deter the rampant offlabel use that has accompanied most other endoluminal devices. Of even greater impact, however, is the fact that unless the CPT code for CAS is upgraded to a noninvestigational status code, there will be continued nonreimbursement for the procedure to hospitals and physicians. Ironically, even after FDA market approval of a CAS system, until the CPT code is upgraded or the policy modified the only avenue for reimbursement of CAS is within an IDE clinical trial.
endovascular cases. While still under active development and refinement, advanced computer processing power has made possible today devices that detect and respond to movements of “catheters” and “guidewires” within a videomonitored computer-simulated case, allowing the operator to perform all of the technical aspects of the case with a variety of wires, catheters, and devices, including cerebral protection systems. Innumerable cases can be programmed in, representing the full spectrum of complexity and difficulty, and allowing a graduated training experience. Potential complications can be triggered by inappropriate technique, requiring salvage maneuvers and secondary procedures. Furthermore, psychometric analysis of performance on a variety of cases can be utilized to pinpoint areas of deficiency in judgment or technique in need of correction. While the concept of computer-simulation training of endovascular procedures is appealing for the potential depth and breadth of its content, its ease of administration, “patient” safety, repeatability, and psychometrics, none of the presently available systems have been validated in any credible fashion. However, the more realistic the systems become the more likely they will provide an authentic training experience. Nonetheless, it remains unknown whether such an experience translates into a smoother learning curve on humans and, if so, how many simulator cases substitute for how many human hands-on cases for the purpose of credentialing. Even absent answers to these questions, however, computer simulation training will undoubtedly be a cornerstone of FDA-mandated CAS training and will, therefore, be launched into the fray of training and credentialing requirements for a number of endovascular procedures. This will drive further innovation in computer simulation, and within the foreseeable future these systems can be expected to be intimately integrated into training, credentialing, and recredentialing of a variety of endovascular procedures. CAS MARCHING ORDERS
GETTING A JUMP ON TRAINING
The limited supply of qualified CAS proctors has spurred a search for mechanisms to leapfrog the learning curve. The limitations of in vitro and animal labs are prohibitive, but one new adjunct to training presently receiving a great deal of attention is computer simulation of CAS and other
While there is no one recipe for getting started in CAS, the more of the following key ingredients you have the more likely you are to enjoy CAS success. Vascular surgeons without comprehensive catheter and guidewire skills must acquire them through training and refine them with experience. If carotid angiography is not a component of your
ESSENTIALS OF ENDOVASCULAR SURGERY TRAINING
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Fig 4. (A) Pre-CAS angiogram showing a focal stenosis in the ICA with smooth vessel origins and minimal tortuosity. (B) Post-CAS of the same patient with a self-expanding stent.
practice, make it one now before conflicting guidelines emerge. Take advantage of opportunities to observe CAS cases done by others to advance your judgment. If at all possible, participate in one of the IDE CAS device trials. If not, offer CAS selectively to patients at increased risk, using offlabel cerebral protection with the knowledge that
neither you nor your hospital will be compensated. Successfully procure most or all of these and you will be well positioned to participate in the CAS revolution, with other issues such as which stent, which embolic protection device, or where the procedure is performed being minor ingredients with many allowable substitutions.
REFERENCES 1. Hodgson KJ, Mattos MA, Sumner DS: Canine or chameleon: the vascular surgeon’s role in percutaneous endovascular therapy. Vasc Forum 1:237-247, 1993 2. White RA, Hodgson KJ, Ahn SA, Hobson RW II, Veith FJ: Endovascular interventions training and credentialing for vascular surgeons. J Vasc Surg 29:177-186, 1999 3. Special Writing Group of AHA Scientific Councils of Car-
diovascular Radiology, Cardio-Thoracic and Vascular Surgery, and Clinical Cardiology: Training standards for physicians performing peripheral angioplasty and other percutaneous peripheral vascular interventions. Circulation 86:1348-1350, 1992 4. Yadav Jay and the Sapphire Investigators: Presented at the Annual Meeting of the American Heart Association, Chicago, Illinois, November 2002.
W
HILE A HANDFUL of vascular surgeons have been advocating and practicing comprehensive endovascular therapy for over a decade1 and have, therefore, evolved their technical skill set with the field, most vascular surgeons only recently entered the endovascular arena, prompted only by the advent of the aortic endografting revolution. Though the limited and relatively crude skill set required to insert an endograft in an aortic aneurysm allowed vascular surgeons to revolutionize their treatment of this condition, the acquired skills provide only meager preparation for the technically demanding procedure of carotid stenting. Additionally, most vascular surgeons have limited their involvement in aortic endografting to the endograft insertion itself, deferring ancillary procedures such as diagnostic angiography, coil embolization, endoleak management, and the endovascular treatment of concomitant disease to their radiologists. The techniques, instrumentation, and anatomical demands of these ancillary procedures more closely mirror those required for carotid stenting, and therein lies the first step a vascular surgeon interested in carotid stenting should consider taking: attainment of comprehen-
From Southern Illinois University, Springfield, IL. Address correspondence to Kim J. Hodgson, MD, Southern Illinois University, P.O. Box 19638, Springfield, IL 62794-9638. © 2003 Elsevier Inc. All rights reserved. 0895-7967/03/1604-0003$30.00/0 doi:10.1053/j.semvascsurg.2003.08.003 262
sive catheter and guidewire skills and development of a broad-spectrum endovascular practice so that they can evolve into carotid stenters. The risks to the patient of a suboptimal carotid angioplasty are simply too great for adoption of this procedure to be a revolution in a vascular surgeon’s practice. Evolving one’s practice is clearly within the reach of most vascular surgeons, as they continue to control the majority of patients with vascular disease, though they typically underutilize these opportunities for their own endovascular growth. While every carotid stent procedure begins with obtaining sheath access to the common carotid artery, most vascular surgeons have no experience even catheterizing these vessels with diagnostic catheters; the most basic step in the procedure beyond obtaining percutaneous femoral access. The catheters and techniques used for such catheterizations are significantly different from those used for aortic endografting, but well within the technical abilities of vascular surgeons to learn. However, opportunities to learn diagnostic carotid angiography have diminished over the past decade as numerous publications documented the accuracy of colorflow carotid duplex scanning and advocated performance of carotid endarterectomy without angiography. Carotid stenting, however, has made it an entirely new ballgame. No longer is the carotid bifurcation the only area of interest if carotid stenting is to be considered as a therapeutic option for a patient. Evaluation of the arch for access issues, and the determination of lesion characteristics, anatomic variations, and confounding secondary lesions all now mandate performance of
Seminars in Vascular Surgery, Vol 16, No 4 (December), 2003: pp 262-269
ESSENTIALS OF ENDOVASCULAR SURGERY TRAINING
a diagnostic carotid angiogram prior to, or at the time of, carotid angioplasty. While carotid angioplasty threatens to take the treatment of carotid bifurcation disease away from vascular surgeons, it also provides an opportunity for those suitably dedicated and committed endovascular surgeons to expand both their diagnostic and therapeutic armamentariums. So, with consideration for carotid angioplasty in mind, performance of diagnostic carotid angiography becomes a justifiable procedure in the evaluation of a patient with carotid bifurcation disease. Furthermore, because the catheters and skills needed to selectively catheterize the common carotid arteries constitute the most difficult aspects of the angioplasty procedure, adopting a routine of obtaining diagnostic angiography and performing it yourself helps refine those skills and prepare you for subsequent angioplasty procedures. Considered from the viewpoint of a credentials committee member evaluating an application to perform carotid angioplasty, it would be much easier to justify granting privileges to treat a vessel to someone who already had experience catheterizing and evaluating that region than to a complete novice in cerebrovascular angiography. Lastly, using preangioplasty angiographic evaluation as your justification to perform a diagnostic study opens the door for you to perform other “planning” endovascular procedures and to argue for access to dedicated angiographic facilities suitable for percutaneous diagnostic angiography. Overall, the benefits of incorporating diagnostic carotid angiography into your practice are multiple and are a requisite initial step towards getting started in carotid stenting. CAROTID CREDENTIALING: WHAT’S IN A BUNDLE?
At this time, the prevailing endovascular credentialing recommendations are those of the Society for Vascular Surgery (SVS)2 and the American Heart Association (AHA),3 neither of which in any way distinguish carotid angiography or angioplasty from analogous procedures in other peripheral vascular territories, or call for separate credentialing of this or any other territory. Some hospital credentials committees have taken this to indicate that carotid procedures are included in the endovascular “bundles” of these documents, while others have established restrictive covenants or supplemental requirements, such as the adoption of those
263
mandated by the U.S. Food and Drug Administration (FDA) for aortic endografting. In this author’s experience, the “unbundlers” for carotid angioplasty are usually motivated by turf or political issues, as the requisite technical skill set needed to safely perform this procedure is no greater than that for renal angioplasty, a vessel comfortably within the bundle. Nonetheless, each physician seeking credentials for carotid angioplasty will need to negotiate the maze of political and credentialing issues specific to their hospital with the knowledge that, at this point, there are numerous examples of vascular surgeons performing this procedure across the country, so it should not be considered a radical departure from accepted practice. And, absent any credentialing standards specific to carotid angioplasty, it should be sufficient to be credentialed under either the SVS or AHA pathways and successfully argue that carotid bifurcation disease is part of your bundle of skills and well-within your logical domain. Ideally, these privileges include access to a dedicated angiographic facility for optimal imaging. It is beyond the scope of this discussion to address legal or political issues related to credentialing for carotid angioplasty, as these are unique to every medical institution during this limbo period where no national standard exists. However, the much-anticipated approval of a carotid angioplasty system expected within the year will likely establish such a standard through the training program requirements adopted with the FDA. Opportunities for training and use of that stent-protection system will also become available, though they may be limited and could take several years to include all vascular surgeons. In the meanwhile, it is relevant to consider some of the nuances of carotid angioplasty that uniquely impact on a hospital’s willingness to credential and permit carotid angioplasty procedures to be performed and, therefore, the vascular surgeon’s ability to adopt this therapy. ALL DRESSED UP AND NOWHERE TO GO
It is often erroneously assumed that credentialing by a hospital is tantamount to being granted permission to perform a procedure in that hospital. In fact, while credentialing does reflect the judgment of the credentials committee that a physician has met a requisite level of training needed to safely perform a procedure, the hospital may still
264
prevent the physician from doing so, even if “credentialed” to do so. Most often this is due to restrictive contracts that grant exclusive rights to perform certain procedures to certain physicians (a perfectly legal situation), or for a variety of other reasons. For carotid angioplasty, a significant “other” reason, is that the procedure is under national noncoverage status from the Center for Medicare and Medicaid Services (CMS). What this means is that, with the exception of patients being treated in a U.S. FDA Investigational Device Exemption (IDE) trial, none of the expenses associated with the carotid angioplasty procedure are reimbursable to either the physician or the hospital. In fact, complications directly arising from a procedure gone bad may also not be covered and could represent huge losses for a hospital. Therefore, the prudent hospital CEO is going to have to carefully weigh the costs of offering this therapy outside of an FDA clinical trial against whatever returns can be expected through marketing the procedure or actually reducing costs in certain truly high-risk patients. The effect of the national noncoverage policy on the ability of vascular surgeons to participate in the carotid angioplasty revolution has been profound. Even vascular surgeons with impeccable skills and reputations have been excluded from this area by virtue of nonparticipation in clinical trials and the national noncoverage policy. The evolution of the carotid angioplasty procedure itself has provided both opportunities and roadblocks to participation. Early on, before embolic protection devices, carotid angioplasty was essentially little different from renal angioplasty; an off-label use of an otherwise approved product, a stent. While compensation may or may not have been occurring, the stents and related equipment were readily available and usually separately billable by the hospital. Consequently, the general decision by vascular surgeons to show restraint at this stage gained us the label of “nonenthusiasts” for the technology. This ultimately hindered our participation in the subsequent clinical trials, into which embolic protection, though of unproven benefit, was incorporated and became the new standard of care. As the clinical trials evolved to include the use of embolic protection devices, however, it became medically and politically difficult to perform carotid angioplasty without embolic protection (EP), yet EP was only available within a clinical trial, few of which
KIM J. HODGSON
included surgeons. This is but one of the ironies of carotid angioplasty for vascular surgeons. WAS IT SOMETHING I SAID?
Beyond failing to adopt and endorse the procedure, many well-known vascular surgeons publicly sniped at the evolving technology and results, an attitude that was erroneously interpreted by industry to indicate widespread negativism by vascular surgeons towards the procedure. While this misperception undoubtedly cost us opportunities for early participation in carotid angioplasty through the clinical trial pathway, by far the greater impediment has been that of industry’s research and development structure. The first wave of the technological endovascular revolution, development of the aortic endograft, was led by companies with close allegiance to vascular surgeons who utilized those relationships throughout their research and development of the products. Unfortunately, those relationships did not translate into widespread involvement in research and development and clinical investigation of subsequent carotid stent systems. In fact, the carotid angioplasty revolution has been dominated by cardiologists, largely through their relationship with the cardiology device industry. While many vascular surgeons have felt excluded, this primarily reflects the business reality that carotid stent development was typically assigned to cardiology divisions within the industry, and those people’s preexisting relationships were primarily with cardiologists. Nonetheless, the overall effect has been to minimize the involvement of vascular surgeons in the entire field of carotid angioplasty, because without trial participation there is no reimbursement to make the procedure economically viable and, until recently, no access to cerebral protection. COULD IT GET ANY MORE UNFAIR?
So, we have a procedure that many vascular surgeons will have to struggle for credentials to perform, which neither the surgeon nor the hospital will get paid for, and which may have to utilize off-label first-generation embolic protection, if any at all. What’s to want for? The solution to all of the issues would appear to be to get into a clinical trial, a wedge often used to pry open credentialing doors, and one that clearly resolves the issues of reimbursement and contemporary cerebral protection. While the industry sponsored FDA IDE trials
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are largely closed to new participation and were always biased towards cardiology anyway, new trials will emerge and the CREST and CARESS trials remain opportunities for vascular surgeons to participate in a clinical trial, and by which to resolve most of the critical issues. But even this avenue is clogged with roadblocks. In order to be considered for CREST or CARESS you have to be able to document satisfactory success in 20 carotid angioplasty cases. Those would be 20 angioplasty cases you had to get your hospital to let you perform gratis and with first-generation (at best) cerebral protection. Once again, the profound impact of the national noncoverage policy, this time potentiated by the clinical trial requirement of prior angioplasty experience. You cannot get into a trial without carotid angioplasty experience and you cannot get carotid angioplasty experience without getting into a trial; if not because of hospital budgetary restraints then because of a commitment to contemporary embolic protection. The rationale for this requirement escapes logic when one considers that these trials have built-in “run-in” phases of up to 20 patients prior to allowing randomization, specifically structured to negate any learning curve issues. Thus, the need for pre– run-in cases has, in this author’s opinion, been more about exclusion of vascular surgeons than bona fide policy. Even if not so intended, it has undeniably resulted in the exclusion from clinical trials of many well-qualified vascular surgeons. MAKING THE BEST OF A BAD SITUATION
The recent FDA approval of the PercuSurge antiembolization system for coronary vein graft dilatation now provides access to an off-label cerebral protection system, albeit without solving the compensation issue. Nonetheless, it does provide an option for those truly high-risk patients who do not qualify for any available trial or are being treated in institutions not participating in such trials, to receive this mode of therapy today. Furthermore, outside of a clinical trial this is probably the only mechanism for vascular surgeons to begin to offer carotid angioplasty and stenting (CAS) to their patients. It is this author’s opinion that there truly are identifiable classes of patients with carotid bifurcation disease who are at higher, though perhaps not prohibitive risk for surgery, for whom CAS is a reasonable option to offer. Examples include restenosis after endarterectomy, a history
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of radical neck dissection or radiation therapy, or high cervical lesions beyond safe surgical exposure. In such cases the vascular surgeon can reasonably argue that, noncoverage policy not withstanding, CAS is the preferred and recommended therapy for this patient. Assuming both the surgeon and hospital are willing to go uncompensated, the procedure would be reasonable. Whether or not a vascular surgeon undertakes the procedure himself or refers the patient to someone else depends on his level of preparation for performing one of the more complex of the endovascular therapies. Assuming the endovascular surgeon is otherwise broadly experienced and possessed of advanced catheter and guidewire skills, evolving into CAS is essentially a matter of learning judgment about case selection and the specific “sequencing” of the procedure rather than specific new technical skills. Sequencing, referring to the choreographed performance of a number of technical steps, can be learned using either in vitro models or animal labs, though clearly both of these models poorly represent human disease and anatomy. Somewhat more authentic training can be obtained by using the PercuSurge device during renal angioplasty procedures where it may also be of benefit and clearly mimics CAS better than other discussed models. A new training modality on the horizon, to be discussed in more detail to follow, is that of computer-simulated training procedures. While clearly these systems provide training in sequencing, their cost is prohibitive if that is all they offer. Judgment is by far the more difficult need to address, as only a handful of operators have significant experience to share. Live-case demonstrations and problem-solving symposia at vascular surgical educational meetings can contribute significantly to one’s understanding of the problematic nuances of the procedure and are highly recommended. While in far from overwhelming numbers, physicians experienced in CAS who are willing to entertain observers and share their knowledge of the procedure, review cases, and perhaps allow hands-on participation are emerging, both in the United States and abroad. Many of them are collaborating closely with industry to aid in training the new workforce once CAS receives its anticipated FDA approval. It is fully anticipated that the training standard adopted at the time of FDA approval will set the standard nationwide for CAS credentialing, not only with that specific de-
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Fig 1. Arch aortogram showing desirable origins of the brachiocephalic vessels high on the arch. Significant stenosis in the innominate artery complicates access to the right common carotid artery and will likely need to be dilated itself. Access to the left common carotid artery is ideal.
vice, but for the procedure itself, even if done using “off-label” devices. Until that standard is set and adopted by individual credentials committees, however, an experienced operator who devotes sufficient time to learning the sequencing of the system in use and proper case selection would be considered adequately prepared to embark on CAS. It goes without saying that early case selection is of particular importance in this contentious area. Several reasonable indications have already been discussed, but technical considerations are also in order. The specific deployment steps applicable to each CAS stent-protection system are variable, frequently changing, and beyond the scope of this article. However, awareness of anatomical issues that may complicate CAS is mandatory for optimal outcomes. Obtaining sheath access to the common carotid artery is the first major component of the CAS procedure and is easiest to accomplish safely in arches relatively free of atheromatous plaque and with high origins of the brachiocephalic vessels off of the top of the arch (Fig 1). Such anatomy minimizes access vessel tortuosity, facilitating sheath placement with the least amount of trauma and need for distal guidewire support. A thorough evaluation of the arch and proximal brachioce-
phalic vessels is in order to ensure that any significant occlusive disease is recognized and considered before deciding whether to treat this first and then perform CAS, perform CAS through the untreated disease, or abandon the CAS procedure altogether. Bovine arches (Fig 2), where the left common carotid artery arises from the innominate artery, can add an additional level of complexity to accessing the left side, the degree of which is variable between patients. Anatomic issues specific to the carotid bifurcation and internal carotid artery (ICA) can also significantly impact the safety of the procedure. Particularly troublesome are deeply ulcerated, irregular, and calcified lesions. Furthermore, lesions in arteries with significant tortuosity within several centimeters of the distal extent of the lesion to be stented (Fig 3) or at the origin of the ICA can also cause challenges. In the former case, deployment of an antiembolic protection device may be problematic or downright impossible, potentially elevating the risk of the procedure done with protection or mandating either unprotected CAS or a carotid endarterectomy. In the latter circumstances, smooth device tracking may be an issue, with a tendency for the device to plow across the surface of the plaque. This may also be a concern when
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Fig 2. Bovine arch configuration complicating access to the left common carotid artery. Vessel origins high on the arch are otherwise ideal.
crossing critically tight stenoses, though device profile is constantly being downsized, and many operators routinely predilate the lesions after deployment of the protection device but before passage of the stent delivery system. Overall, the ideal anatomy is a patient with a high origin of the common carotid artery, off of an arch free of atheromatous disease, with a smooth focal subcritical stenosis in an ICA that originates from the carotid bulb without abrupt angulation and maintains a straight course well beyond the lesion to be treated (Fig 4). THE MORNING AFTER
Based on the reported 30-day data of the SAPPHIRE trial,4 FDA approval of a CAS system is anticipated within the next 12 months. Vascular surgeons would be mistaken, however, to think that they will then have ready access to the device to utilize liberally in their practices and receive compensation for. Firstly, the “roll-out” of the device is likely to be more controlled than with aortic endografts, reflecting lessons learned from that new device introduction and training program. Consequently, opportunities to participate in the FDA-mandated training program for CAS will be limited, and until such training is received, product
cannot be sold. Furthermore, vascular surgeons will be competing with two other specialties, interventional radiology and cardiology, for available training slots. How rigorous the mandated training is will also determine the availability of training opportunities. It is likely that there will be a requirement for actual human hands-on cases as the primary operator under supervision before the procedure can be performed independently. The number of required cases and whether they can be done at one’s home institution on one’s own patients or will require one to venture to another institution will both impact heavily on the number of opportunities to fulfill the training requirements. In the case where a new locale is required, outside credentialing and possibly an additional medical license will undoubtedly slow and limit this training pathway. While certainly desirable, successful completion of FDA-mandated CAS training may not actually significantly change the nature of your carotid practice for two reasons. First, there is reason to believe that CMS is planning to adopt measures to ensure that payment for CAS is only provided when performed in patients with the specific device labeling indications, essentially “high-risk” patients only. While the qualifying indications may
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Fig 3. A loop in the ICA just distal to the lesion to be dilated precludes utilization of most antiembolic filters, which require a straight segment of ICA beyond the lesion.
be loose and the enforceability impractical, the message will undoubtedly deter the rampant offlabel use that has accompanied most other endoluminal devices. Of even greater impact, however, is the fact that unless the CPT code for CAS is upgraded to a noninvestigational status code, there will be continued nonreimbursement for the procedure to hospitals and physicians. Ironically, even after FDA market approval of a CAS system, until the CPT code is upgraded or the policy modified the only avenue for reimbursement of CAS is within an IDE clinical trial.
endovascular cases. While still under active development and refinement, advanced computer processing power has made possible today devices that detect and respond to movements of “catheters” and “guidewires” within a videomonitored computer-simulated case, allowing the operator to perform all of the technical aspects of the case with a variety of wires, catheters, and devices, including cerebral protection systems. Innumerable cases can be programmed in, representing the full spectrum of complexity and difficulty, and allowing a graduated training experience. Potential complications can be triggered by inappropriate technique, requiring salvage maneuvers and secondary procedures. Furthermore, psychometric analysis of performance on a variety of cases can be utilized to pinpoint areas of deficiency in judgment or technique in need of correction. While the concept of computer-simulation training of endovascular procedures is appealing for the potential depth and breadth of its content, its ease of administration, “patient” safety, repeatability, and psychometrics, none of the presently available systems have been validated in any credible fashion. However, the more realistic the systems become the more likely they will provide an authentic training experience. Nonetheless, it remains unknown whether such an experience translates into a smoother learning curve on humans and, if so, how many simulator cases substitute for how many human hands-on cases for the purpose of credentialing. Even absent answers to these questions, however, computer simulation training will undoubtedly be a cornerstone of FDA-mandated CAS training and will, therefore, be launched into the fray of training and credentialing requirements for a number of endovascular procedures. This will drive further innovation in computer simulation, and within the foreseeable future these systems can be expected to be intimately integrated into training, credentialing, and recredentialing of a variety of endovascular procedures. CAS MARCHING ORDERS
GETTING A JUMP ON TRAINING
The limited supply of qualified CAS proctors has spurred a search for mechanisms to leapfrog the learning curve. The limitations of in vitro and animal labs are prohibitive, but one new adjunct to training presently receiving a great deal of attention is computer simulation of CAS and other
While there is no one recipe for getting started in CAS, the more of the following key ingredients you have the more likely you are to enjoy CAS success. Vascular surgeons without comprehensive catheter and guidewire skills must acquire them through training and refine them with experience. If carotid angiography is not a component of your
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Fig 4. (A) Pre-CAS angiogram showing a focal stenosis in the ICA with smooth vessel origins and minimal tortuosity. (B) Post-CAS of the same patient with a self-expanding stent.
practice, make it one now before conflicting guidelines emerge. Take advantage of opportunities to observe CAS cases done by others to advance your judgment. If at all possible, participate in one of the IDE CAS device trials. If not, offer CAS selectively to patients at increased risk, using offlabel cerebral protection with the knowledge that
neither you nor your hospital will be compensated. Successfully procure most or all of these and you will be well positioned to participate in the CAS revolution, with other issues such as which stent, which embolic protection device, or where the procedure is performed being minor ingredients with many allowable substitutions.
REFERENCES 1. Hodgson KJ, Mattos MA, Sumner DS: Canine or chameleon: the vascular surgeon’s role in percutaneous endovascular therapy. Vasc Forum 1:237-247, 1993 2. White RA, Hodgson KJ, Ahn SA, Hobson RW II, Veith FJ: Endovascular interventions training and credentialing for vascular surgeons. J Vasc Surg 29:177-186, 1999 3. Special Writing Group of AHA Scientific Councils of Car-
diovascular Radiology, Cardio-Thoracic and Vascular Surgery, and Clinical Cardiology: Training standards for physicians performing peripheral angioplasty and other percutaneous peripheral vascular interventions. Circulation 86:1348-1350, 1992 4. Yadav Jay and the Sapphire Investigators: Presented at the Annual Meeting of the American Heart Association, Chicago, Illinois, November 2002.