Patient-specific simulation in carotid artery stenting

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1 EDUCATION CORNER Patient-specific simulation in carotid artery stenting Willem Willaert, MD, a,d Rajesh Aggarwal, PhD, a Colin Bicknell, MD, a,b Mo Hamady, MD, c Ara Darzi, MD, a Frank Vermassen, PhD, d and Nicholas Cheshire, MD, a,b on behalf of the European Virtual Reality Endovascular Research Team (EVEResT), London, United Kingdom; and Ghent, Belgium Aims: Patient-specific virtual reality (VR) simulation is a technologic advancement that allows planning and practice of the carotid artery stenting (CAS) procedure before it is performed on the patient. The initial findings are reported, using this novel VR technique as a tool to optimize technical and nontechnical aspects of this complex endovascular procedure. Methods: In the angiography suite, the same interventional team performed the VR rehearsal and the actual CAS on the patient. All proceedings were recorded to allow for video analysis of team, technical, and nontechnical skills. Results: Analysis of both procedures showed identical use of endovascular tools, similar access strategy, and a high degree of similarity between the angiography images. The total procedure time (24.04 vs minutes), fluoroscopy time (11.19 vs minutes), and cannulation of the common carotid artery (1.35 vs 9.34) took considerably longer in reality. An extensive questionnaire revealed that all team members found that the rehearsal increased the subjective sense of teamwork (4/5), communication (4/5), and patient safety (4/5). Conclusion: A VR procedure rehearsal is a practical and feasible preparatory tool for CAS and shows a high correlation with the real procedure. It has the potential to enhance the technical, nontechnical, and team performance. Further research is needed to evaluate if this technology can lead to improved outcomes for patients. (J Vasc Surg 2010;52: ) The last decade has seen a growing interest in the application of endovascular virtual reality (VR) simulation for carotid artery stenting (CAS) training. 1 Recent technologic advancements have made it possible to incorporate patient-specific computed tomography (CT) data into the simulation, signalling a shift in the use of simulation not solely as a generic training tool but also to plan and rehearse real patient cases. This has been referred to as mission, simulation case, or procedure rehearsal. 2-4 This kind of rehearsal and planning seems especially appropriate for CAS, because it is a high-risk procedure where the experience of the operator seems to be closely related to outcome. 5 Incidental reports have already shown that it is feasible to use this technology for patients undergoing CAS and that it may aid the interventionalist in the selection of endovascular tools. 2-4 This technology, however, has the potential to be more than just a technical adjunct to the interventionalist alone. It is well established that procedural success in complex tasks is the result of the utilization of adequate technical as From Department of Biosurgery and Surgical Technology, a Regional Vascular Unit, b and Department of Interventional Radiology, c St Mary s Hospital, Imperial College Healthcare NHS Trust, London; and Department of Thoracic and Vascular Surgery, Ghent University Hospital, Ghent. d Competition of interest: none. Correspondence: W.I.M. Willaert, MD, Ghent University Hospital, Department of Thoracic and Vascular Surgery, De Pintelaan 185, 9000 Ghent, Belgium ( wimwillaert@hotmail.com). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a competition of interest /$36.00 Copyright 2010 by the Society for Vascular Surgery. doi: /j.jvs well as nontechnical skills. Human factors such as teamwork, situational awareness, communication, and decision making are vital aspects to ensure a good outcome after any operative procedure. Therefore, this is the first report, to our knowledge, that describes the use of VR mission rehearsal, to enhance not only the technical but also the nontechnical aspects of a CAS procedure. This was accomplished by involving all members of the interventional team and performing the mission rehearsal in a realistic clinical environment. METHODS Patient selection. The patient, a 70-year-old man, was referred to St. Mary s Hospital, Imperial College Healthcare NHS Trust, in London, with an asymptomatic 85% left internal carotid (ICA) stenosis. The CT demonstrated a type II aortic arch without major calcifications, with a relatively straight carotid vessel. This favorable anatomy suggested the stenting procedure would be feasible and present a relatively low operative risk. The patient had no major comorbidities. Simulator device and 3-dimensional model reconstruction. The day before the actual CAS intervention, the Simbionix PROcedure rehearsal studio software (Simbionix USA Corp, Cleveland, Ohio) was used to create a 3-dimensional (3D) reconstruction of the CT Digital Imaging and Communications in Medicine (DICOM) data. Although CT data were used, DICOM data obtained from magnetic resonance angiography can also be uploaded into the simulation software. These data were uploaded into the simulation software by a standard data carrier. A subsequent 3D reconstruction

Components include the (1) video camera (for recording hands); (2) fluoroscopy monitor; (3) laptop computer; (4) mechanical interface haptics device; and (5) sheath through which endovascular tools

2 JOURNAL OF VASCULAR SURGERY Volume 52, Number 6 Willaert et al 1701 Fig 1. Set up of the Simbionix Angiomentor Express Simulator in the angiography suite before performing a patientspecific procedure rehearsal. Components include the (1) video camera (for recording hands); (2) fluoroscopy monitor; (3) laptop computer; (4) mechanical interface haptics device; and (5) sheath through which endovascular tools are inserted. was created from the source CT data, by both an automated and manual level set method of data segmentation. The software automatically marks an initial mask consisting of a set of voxels representing the anatomy of interest (ie, the carotid and adjacent arteries). This mask can then be enhanced manually. Subsequent vessel centerlining is an automated process and works very efficiently. The end result is a reconstruction with centerlining that forms the anatomic scaffold for the simulation and is uploaded automatically into the VR simulation. The set-up of the patientspecific simulation took 60 minutes. The simulation was performed on the AngioMentor Express simulator (Simbionix USA Corp; Fig 1). Simulation environment. At Imperial College, the laboratory environment (Fig 2), the simulated operating suite (Fig 3), and the real angiography suite (Fig 1) are available as simulation environments. Because the angiography suite was available at the time of the rehearsal, this was chosen as the simulation environment. The operating table, fluoroscopy screens, and the simulator (resembling the patient) were placed identically to the real-life setting (Fig 1). All proceedings were recorded for future post hoc video analysis of the technical and nontechnical skills of each individual team member and the team as a whole. When the angiography suite is not available, the simulated operating suite is also used to conduct simulated rehearsals. This environment consists of a replicated, fully functional, operating theater environment and an adjacent control room. Interactions between individuals are recorded using unobtrusively placed microphones and cameras, allowing for performance assessment. Fig 2. Set up of the simulator in the laboratory environment. RESULTS Team and technical outcome. The entire interventional team was involved in both the procedure rehearsal and subsequent real CAS. An exception was the circulating nurse, who was not available for the rehearsal. The other team members consisted of an interventionalist and vascular surgeon performing the procedure together, an assistant, a scrub nurse, and a radiographer. An extensive ques-

3 1702 Willaert et al JOURNAL OF VASCULAR SURGERY December 2010 Fig 3. Top, Set up of the simulator in the simulated operating suite (SOS), (lower left) with team practice in the SOS and (lower right) performing the real case in the angiography suite. tionnaire evaluated each team member s opinions with regard to simulation realism (face validity) and various technical, team, and communication issues. This was done using a Likert scale ranging from 1 (definitely disagree) to 5 (definitely agree). An abbreviated example of the questionnaire is given in Fig 4. The interventionalist indicated that the simulation had aided in the choice of endovascular material (median score, 5/5) and decreased the procedure and fluoroscopy time (4/5). All team members agreed the simulation set up was realistic (5/5) and had similar outcomes as the real case (4/5). An exception was the crossing of the stenotic lesion in the ICA, which was regarded as too easy in the simulation (2/5). All members found the rehearsal useful (5/5) and believed it increased the operative flow (5/5) and increased their subjective sense of patient safety (4/5). They also agreed it increased the coordination (4/5), communication (4/5), and overall team performance and made them feel more confident in their respective roles (4/5). This was especially true for the scrub nurse (5/5), who was relatively inexperienced in the CAS procedure. On the technical front, a high concordance was seen between the real and virtual operation in operative metrics, angiography (Fig 5), and tools preferences (Table). However, notable differences were the longer procedure (60.44 vs minutes), cannulation, and fluoroscopy times for

4 JOURNAL OF VASCULAR SURGERY Volume 52, Number 6 Willaert et al 1703 Fig 4. An abbreviated example of the questionnaire to assess each team member s opinion on simulation realism and its value with regard to technical, team, and communications issues. the real case and the higher amount of contrast used in the real case (120 vs 70 ml). DISCUSSION Although initial observational studies suggested CAS was safe and effective in treating carotid stenotic disease, the most recent reports indicate that CAS might be associated with an increased risk for periprocedural strokes compared with carotid endarterectomy. 6,7 This has led to a decrease in the number of CAS procedures being performed worldwide. Although the reason for the disappointing results is multifactorial, the relative inexperience of

1704 Willaert et al JOURNAL OF VASCULAR SURGERY December 2010 Fig 5. Left, Real patient angiographic images of the (top) aortic arch and (bottom) left internal carotid artery.

5 1704 Willaert et al JOURNAL OF VASCULAR SURGERY December 2010 Fig 5. Left, Real patient angiographic images of the (top) aortic arch and (bottom) left internal carotid artery. Right, Same vessels in the virtual reality simulation. interventionalists in these studies has been suggested as an important factor. 5 As a result, ever more emphasis is placed on adequate training of interventionalists before independent CAS practice. As far back as 2004, the U.S. Food and Drug Administration indicated that simulation should be an important part of any CAS training program. 8 Research conducted since then has shown that endovascular VR simulation has the ability to train interventionalists in the CAS procedure. 1 The recent introduction of patient-specific VR rehearsal signals a shift in the use of endovascular simulation, not only as a generic training tool for skills acquisition but also as a tool to allow case-specific rehearsal and planning. Although this concept of procedure-specific training is new in medical practice, it has already been implemented in other high-stake domains, such as the military, aerospace, and sports industries. 9 Since its recent introduction in medicine, three reports have now shown the feasibility of using this technology in the clinical setting. 2-4 However, the primary focus of these reports is on the interventionalist, who performs the simulation in the laboratory environment before the actual procedure. Although this is undoubtedly a very important facet, procedure rehearsal has the potential to be much more than just an instrument to experiment with different endovascular tools. The present report differs from the previous reports, because the emphasis is not solely on the role of the simulator as a technical adjunct, but also as a training tool to increase the performance of the whole interventional team. This involves enhancing facets such as teamwork, leadership, and communication. The importance of the nontechnical aspects in the outcome of complex tasks is well documented. Human errors in the operating theater are rarely due to deficiencies in technical performance alone, but are often the result of suboptimal behavioral performance in nontechnical areas leading to mistakes and poor outcomes. 10 In medicine, a study of anesthetic-related errors considered 80% of the occurrences to be preventable, with human error accounting for 75%. 11 This has led to the development of anesthesia crisis resource management centers across the globe. These centers mirror what has already taken place in the aviation, manufacturing, and nuclear industries, where crew resource management training, consisting of seminars, lectures, and simulator-based training, has proven highly effective in minimizing the effect of human error on overall performance. 12,13 Much like in anesthesia, it seems reasonable to suggest that endovascular simulation may also be used as part of a program to enhance the safety in the angiography suite or operating room, through both technical and nontechnical team training. The procedure rehearsal capability of these new simulators can even tailor this kind of training and preparation to the specific scenario of a real patient. The results from the present report certainly support this view, as the different team members indicated that the rehearsal had increased their overall confidence, communication, and team performance. In their opinion, this increased the operative flow and level of patient safety. From a technical perspective, similar outcomes to the report by Cates et al 3 were observed. The simulator predicted the correct angiography images (Fig 5), fluoroscopy angles, and endovascular material for the case (Table). However, more roadmaps were necessary during the real operation (13 vs 6) because unforeseen patient movements in real life necessitated repeat angiographies. This is not the case for the simulated patient. More roadmaps also resulted in the use of more contrast medium. As seen in previous case reports, the total procedure time and fluoroscopy time is invariably shorter in simulated cases. The reasons for this include the immediate availability of different endovascular equipment and the more rapid exchange of these tools, no patient draping, and no patient movements. In this specific case, less time was also spent cannulating the common carotid artery, with a subsequent reduction in total time and fluoroscopy time. The postoperative questionnaires indicated that the rehearsal was useful in determining the optimum tools during the procedure, although it also highlighted that the simulation did not fully replicate the difficult cannulation of the tortuous common and internal carotid arteries. The simulator can react differently to certain vessel characteristics, which has been noted by other authors. 2,3 Therefore, the improvement of the software fidelity of VR simulators should remain a focal point to ensure they are able to adequately reflect reality. Only then will they be able to perfectly predict the technical planning of real procedures and aid in patient selection and choosing the appropriate material for technically demanding cases.

6 JOURNAL OF VASCULAR SURGERY Volume 52, Number 6 Willaert et al 1705 Table. Metrics for the virtual reality (VR) and real carotid artery stenting (CAS) case Variable Virtual reality CAS Real CAS Operative metrics, min Procedure time Fluoroscopy time Time to cannulate CCA Time to cannulate ICA & deploy EPD Angiography Total contrast use, ml Total roadmaps, No Angle of arch angiography Angle of selective angiography Endovascular tool choice Introduction guidewire, inches J-tip, J-tip, Guidewire to cannulate CCA, inches Glide, Glide, Exchange guidewire, inches Superstiff, Superstiff, Selective catheter Headhunter, 5F Headhunter, 5F Guiding catheter Multipurpose, 8F Multipurpose, 8F EPD filter Eccentric Concentric, 5 mm Stent, mm Closed cell, 7 30 Closed cell 7 30 Postdilation balloon, mm CCA, Common carotid artery; EPD, embolic protection device; ICA, internal carotid artery. CONCLUSIONS The early development phase of patient-specific VR rehearsal shows that setting up a procedure rehearsal is feasible in the clinical setting. Furthermore, procedure rehearsal has a high concordance with the real procedure and has the potential to enhance both the technical and nontechnical skills of the interventionalist and his/her team members. It seems probable that the inexperienced interventionalist and team might apply this for most of the interventional cases in the start up of their practice. The experienced practitioner, however, might concentrate on the more challenging patient cases or rehearse only the essential parts of a procedure to make the process less time consuming. Further research will evaluate if the application of this technology can thus reduce perioperative complications, not only by aiding the interventionalist in choosing the optimal endovascular material but also by optimizing the nontechnical skills of the interventionalist and the team. This research may eventually lead to the implementation of such a device to improve patient outcomes during CAS and perhaps in a variety of other endovascular procedures. REFERENCES 1. Van Herzeele I, Aggarwal R, Neequaye S, Hamady M, Cleveland T, Darzi A, et al. Experienced endovascular interventionalists objectively improve their skills by attending carotid artery stent training courses. Eur J Vasc Endovasc Surg 2008;35: Hislop SJ, Hedrick JH, Singh MJ, Rhodes JM, Gillespie DL, Johansson M, et al. Simulation case rehearsals for carotid artery stenting. Eur J Vasc Endovasc Surg 2009;38: Cates CU, Patel AD, Nicholson WJ. Use of virtual reality simulation for mission rehearsal for carotid stenting. JAMA 2007;297: Roguin A, Beyar R. Real case virtual reality training prior to carotid artery stenting. Catheter Cardiovasc Interv. 2010;75: Verzini F, De Rango P, Parlani G, Panuccio G, Cao P. Carotid artery stenting: technical issues and role of operators experience. Perspect Vasc Surg Endovasc Ther 2008;20: SPACE Collaborative Group, Ringleb PA, Allenberg J, Brückmann H, Eckstein HH, Fraedrich G, et al. 30 day results from the SPACE trial of stent-protected angioplasty versus carotid endarterectomy in symptomatic patients: a randomised non-inferiority trial. Lancet 2006;368: ; erratum in: Lancet 2006;368: Mas JL, Chatellier G, Beyssen B, Branchereau A, Moulin T, Becquemin J, et al; for the EVA-3S Investigators. Endarterectomy versus stenting in patients with symptomatic severe carotid stenosis. N Engl J Med 2007; 356: US Food and Drug Administration Center for Devices and Radiological Health Medical Devices. Advisory committee circulatory system devices panel meeting. Gaithersberg, MD; Apr 21, gov/ohrms/dockets/ac/04/transcripts/4033t1.htm. 9. Krebs WK, McCarley JS, Bryant EV. Effects of mission rehearsal simulation on air-to-ground target acquisition. Hum Factors 1999;41: Yule S, Flin R, Paterson-Brown S, Maran N. Non-technical skills for surgeons in the operating room: a review of the literature. Surgery 2006;139: Chopra V, Bovill JG, Spierdijk J, Koornneef F. Reported significant observations during anesthesia: a prospective analysis over an 18-month period. Br J Anaesth 1992;68: Helmreich RL, Wilhelm JA, Gregorich SE, Chidester TR. Preliminary results from the evaluation of cockpit resource management training: performance ratings of flightcrews. Aviat Space Environ Med 1990;61: Wiener EL, Kanki BG, Helmreich RL. Cockpit resource management. San Diego: Academic Press Inc; Submitted Apr 19, 2010; accepted Aug 4, 2010.

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