Cassidy Duran

A nationwide survey of vascular surgery trainees reveals trends in operative experience, confidence, and attitudes about simulation.

OBJECTIVE There is mounting evidence supporting the benefit of surgical skills training in a simulated environment. However, the use of simulation in vascular surgery has been limited, and its value has been poorly understood. Access to simulation is presumed to be a major barrier to its widespread implementation. While a great deal of discussion is taking place at the national level, input from current trainees has not been obtained. METHODS The Association of Program Directors in Vascular Surgery Committee on Education and Simulation sent a survey to all vascular surgical trainees assessing access to vascular simulation, the perceived value of simulation, and expectations for the future. Data were analyzed for junior (postgraduate year ≤ 4; n = 73) and senior (postgraduate year ≥ 5; n = 110) level and program type (traditional = 5 + 2/4 + 2; integrated = 0 + 5). RESULTS A total of 183 of 326 (56%) trainees completed the survey, 72 (0-5), 5 (4+2), 111 (5+2), respectively. Of the respondents, 86% believe there is educational value in simulation. Cadaver dissections, followed by peripheral endovascular simulators and endovascular aortic aneurysm repair simulators, were ranked the most valuable tools by seniors, while anastomotic models are valued most by juniors, followed by cadavers and endosimulators. Fifty-six percent of programs currently offer simulation training, most commonly in the form of peripheral endovascular simulators (70%), anastomotic models (58%), or endovascular aortic aneurysm repair simulation (53%). Senior residents are more likely than juniors to have attended outside simulation courses (37% vs 19%). Overall, 57% of trainees expect that technical skills assessment will be incorporated into the certification process, and 52% endorse skills assessment for certification. CONCLUSIONS Trainees report limited operative experience and confidence, and confidence levels are improved for a number of index procedures among those trainees with access to simulation. Trainees endorse the use of simulation to augment their surgical training, and a significant proportion of them already have access to it. These data support a perceived need and utility for implementation of a standardized simulation curriculum in vascular surgical training.

A first-in-man study of the role of flexible robotics in overcoming navigation challenges in the iliofemoral arteries

OBJECTIVE Current interventional techniques rely heavily on operator familiarity with catheters and wires and on physician skills in effectively navigating through and managing target lesions. A novel robotic technology allows endovascular specialists to remotely control catheter tip deflection and advancement and to coordinate manipulation of currently available wires. The aim of this study was to successfully demonstrate feasibility and safety of navigation to and treatment of iliac and femoral artery lesions using Hansen Medicals vascular control catheter (VCC). METHODS A total of 20 limbs were included in this analysis for a first-in-man trial of the VCC and vascular catheter control system. The local Institutional Review Board approved the trial, and all patients included had symptomatic femoropopliteal occlusive disease. Preoperative imaging was available on all patients. Target lesions in the contralateral superficial femoral artery ranged from mild stenosis to chronic total occlusions (TransAtlantic Inter-Society A through D). Exclusion criteria included previously treated iliac and femoral lesions in the symptomatic leg and a body mass index >35. The operators comprised three experienced interventionalists (two vascular surgeons and an interventional radiologist) and a novice (cardiac surgeon). The primary end point of the study was to demonstrate successful cannulation of the target vessel (ie, navigation to the lesion with wire and catheter) with the Hansen VCC, with no device-related serious adverse events. Secondary end points were to assess the ability to treat lesions using the flexible catheter defined by successful insertion of a guidewire, angiography of the target vessel, delivery of balloon, and/or stent. Procedure times and radiation delivered were analyzed for the group and by operator, and t-test was performed to determine statistical significance. Complications were assessed by clinical examination and ultrasound. RESULTS Lesions were successfully and safely cannulated in all limbs treated. The VCC performed as designed in all cases. All interventionalists, regardless of experience, navigated the VCC with ease. However, statistically significant differences in navigation time and radiation per case were observed between the experienced and inexperienced interventionalists. There were no access site complications (hematoma, thrombosis, pseudoaneurysm) as evaluated by ultrasound. CONCLUSIONS This initial experience in flexible robotics demonstrates that this technology is both efficacious and safe in the arterial tree. Although robotics provides superior maneuverability compared with current techniques, endovascular experience is crucial to taking full advantage of the extra capabilities. Valuable future considerations will include off-the-wall (center lumen) navigation with three-dimensional imaging.

Comparison of Outcomes of One-Stage Basilic Vein Transpositions and Two-Stage Basilic Vein Transpositions

BACKGROUND Basilic vein transpositions (BVTs) provide autologous hemodialysis access in the upper extremity. We report and compare our experience using the two techniques that are commonly performed to create BVTs: the one-stage and the two-stage technique. METHODS A retrospective review was performed on patients who underwent BVT from June 2006 to June 2010 from a database of all patients undergoing dialysis access procedures. One hundred six patients, mean age of 54 years (41% male), who received upper-arm basilic vein-only transposition were identified and were stratified based on one-stage and two-stage BVTs. Anatomic outcomes and functionality were determined and compared between stages. RESULTS Seventy-seven patients underwent two-stage BVT, and 29 underwent one-stage BVT. Fifty-one percent and 79% of the two-stage group and the one-stage group, respectively, had had a previous failed ipsilateral permanent access. Catheter dialysis at time of surgery was 14% in one-stage BVT and 43% in two-stage BVT. Immediate technical success was obtained in all cases. The rate of primary failure was 21% in the one-stage group and 18% in the two-stage group. Reintervention rates for the one-stage group and the two-stage group were 62% and 66%, respectively. Primary patency for the one-stage group and the two-stage group at 1 year was 82% and 67%, at 2 years was 81% and 27%, and at 3 years was 51% and 18%, respectively. Secondary patency for the one-stage group and the two-stage group at 1 year was 91% and 81%, at 2 years was 80% and 61%, and at 3 years was 58% and 45%, respectively. Thirty-day mortality was 0% in both groups, and all-cause morbidity was 12% in both groups (counting all stages). CONCLUSION One-stage BVTs have a similar number of initial failures and secondary interventions as two-stage BVTs. One-stage BVTs achieved better primary and cumulative patencies. There appears to be no advantage to a two-stage BVT in equally matched patients.

Preliminary findings in quantification of changes in septal motion during follow-up of type B aortic dissections

OBJECTIVE To quantify longitudinal changes in intra-arterial septum (IS) motion with two-dimensional (2D) phase-contrast magnetic resonance imaging (2D pcMRI) in type B aortic dissections (AD) to improve the understanding of AD and its midterm development. METHODS From a database of 42 patients who underwent a dynamic magnetic resonance imaging (MRI) examination at the Acute Aortic Treatment Center of The Methodist DeBakey Heart & Vascular Center, 2D pcMRI image data was available from 10 patients with type B AD for both short-term (mean, 6.6 days; range, 1-10 days; n = 7) and midterm follow-up (mean, 155 days; range, 60-324; n = 5). IS motion was quantified as motion of IS boundary points averaged over the cardiac cycle. Relative change in IS motion was expressed as percent change compared with initial presentation. Maximum IS extension (true lumen [TL] expansion) and contraction (TL compression), IS fraction in phase with aortic flow and correlation of IS motion with aortic flow (IS compliance) were quantified. RESULTS IS motion at initial presentation was 0.68 ± 0.2 mm and was reduced at short-term (0.48 ± 0.3 mm; P = .07) and midterm (0.5 ± 0.2 mm; P = .1) follow-up. Trend in relative change of IS motion was variable during short-term follow-up: reduced in three subjects (-75% ± 6%) and elevated in four subjects (48% ± 23%). During midterm follow-up, relative change in IS motion was reduced in four subjects (28% ± 19%) and slightly elevated in one (6.2%). IS contraction decreased with follow-up while IS extension slightly increased. Fraction of IS moving in phase with aortic flow increased but IS compliance decreased, suggesting increasing IS stiffness. CONCLUSIONS Reduction of IS motion in AD is seen with short-term and midterm follow-up. Intersubject variability of this trend is high at short-term follow-up but low at midterm follow-up. Detailed analysis of IS motion parameters indicate reduction of IS contraction and IS compliance with time. This has potential implications for endovascular management of type B aortic dissections, as expansion of aortic stent grafts can be limited by a stiff IS.

On the development of objective metrics for surgical skills evaluation based on tool motion

A key competency requirement in endovascular surgery is to optimally visualize and utilize pre-shaped catheters to navigate complex vascular anatomy, yet current performance assessment techniques are limited to grading scales based solely on observation. Since most endovascular procedures involve performing fine motor control tasks that require complex, dexterous movements, this paper explores the potential for a standardized, objective, and quantitative means of measuring technical competence based on analysis of the kinematics of endovascular tool tip motions. To accomplish this goal, we recorded catheter tip movement from twenty subjects performing fundamental endovascular tasks in an inanimate model and in a simulation environment with a virtual representation of the same inanimate model. Several motion-based performance measures that have been shown to reliably assess skill in other domains were computed and tested for correlation with data that were obtained from the global rating scale assessment tool. The metrics that quantified movement quality by assessing movement smoothness produced reliable correlations with the observation-based assessment metrics. These objective and quantitative metrics that capture movement quality could be incorporated into future training protocols to provide detailed feedback on trainee performance.

A randomized, controlled animal trial demonstrating the feasibility and safety of the Magellan™ endovascular robotic system

BACKGROUND The success of remotely steerable catheters designed for cardiac ablation procedures in the peripheral vasculature (in the laboratory and in highly select live cases) has led to the development of a vascular robotic system designed specifically for use in the arterial and venous systems. Limited bench-top and animal testing has been successful, but no randomized, controlled study of the systems safety has been performed. METHODS In a 3-phase study, we performed a randomized, controlled trial comparing standard manual catheterization and balloon angioplasty of visceral, renal, and contralateral lower extremity vessels in a porcine model. We also demonstrated feasibility of standard device deployment through the system. RESULTS There was 100% technical success in test (robotic) and control (manual) arm cannulation and balloon angioplasty of all target vessels, without complications. Pathologic analysis at 7 days revealed significantly fewer traumatic lesions in the test animal arm as compared with the control arm (P < 0.001) and, by 30 days, all lesions had healed in both groups. There was 100% success in delivery of standard devices (balloons and stents) without complications. CONCLUSIONS Remotely steerable robotic catheters are at least as safe as manual catheter techniques, and may prove less traumatic to peripheral vessels. Standard devices can be deployed through the system, and the stability of the platform may aid in ease of device delivery in difficult vascular segments.

A longitudinal view of improved management strategies and outcomes after iatrogenic iliac artery rupture during endovascular aneurysm repair.

BACKGROUND Intraoperative rupture of the iliac artery is a serious complication of endovascular aneurysm repair (EVAR), the outcomes of which have changed with increasing experience and improved endovascular tools over the past 2 decades. Over the past 15 years, the incidence and management of iliac rupture has changed as devices have improved and experience has grown. This study reviews our longitudinal experience with this complication. METHODS All cases of iliac artery rupture during EVAR from 1997 through 2011 were reviewed for presentation, treatment strategies, and outcomes. RESULTS Iliac artery rupture complicated 20 (3%) of 707 EVARs performed. Sixteen (80%) common and four (20%) external iliac arteries were ruptured. Hypotension (systolic blood pressure: <90 mm Hg) was present in 11 (55%) cases. Five open bypasses were performed (25%), whereas 15 were repaired using an endovascular approach (75%). All open repairs (100%) were associated with postoperative morbidity (one wound infection, four multiorgan system failure), whereas three of the 15 patients (23%) repaired endovascularly experienced postoperative morbidity (cerebrovascular accident, myocardial infarction, line infection). There were no intraoperative deaths. There were four (20%) early deaths in the intensive care unit (<3 days postoperatively), all of which were associated with resection of bilateral hypogastric arteries and were due to complications of pelvic ischemia and/or multiorgan system failure. CONCLUSIONS Iliac artery rupture remains relatively uncommon but can carry a high morbidity and mortality. As device technology, imaging quality for preoperative planning, and experience level have improved, iliac rupture has become less common, and outcomes in the setting of iliac rupture have significantly improved. Endoluminal management has evolved as the primary treatment strategy. Resection of both hypogastric arteries is associated with mortality from pelvic ischemia, a likely indicator of systemic disease.

Smoothness of Surgical Tool Tip Motion Correlates to Skill in Endovascular Tasks

Current performance assessment techniques in endovascular surgery are subjective or limited to grading scales based solely on an experts observation of a novices task execution. Since most endovascular procedures involve performing fine motor control tasks that require complex dexterous movements, this paper evaluates objective and quantitative metrics of performance that capture movement quality through the computation of tool tip movement smoothness. An experiment was designed that involved recording the catheter tip movement from 20 subjects performing four fundamental endovascular tasks in each of three sessions using manual catheterization on a physical model and in a simulation environment. Several motion-based performance measures that have been shown to reliably assess skill in other domains were computed and tested for correlation with subjective data that were simultaneously obtained from the global rating scale assessment tool. Metrics that captured movement smoothness produced statistically significant correlations with the observation-based assessment metrics and were able to differentiate skill among participants. In particular, submovement analysis led to metrics that captured statistically significant differences across ability group, session, experimental platform, and task. Objective and quantitative metrics that capture movement smoothness could be incorporated into future training protocols to provide detailed feedback on trainee performance.

Validated assessment tool paves the way for standardized evaluation of trainees on anastomotic models.

BACKGROUND Simulation modules allow for the safe practice of certain techniques and are becoming increasingly important in the shift toward education for integrated vascular residents. There is an unquestionable need to standardize the evaluation of trainees on these simulation models to assure their impact and effectiveness. We sought to validate such an assessment tool for a basic open vascular technique. METHODS Vascular fellows, integrated vascular residents, and general surgery residents attending Society for Clinical Vascular Surgery, Introduction to Academic Vascular Surgery, and Methodist Boot Camp in 2012 were asked to participate in an assessment model using multiple anastomotic models and given 20 minutes to complete an end-to-side anastomosis. Trained vascular faculty evaluated subjects using an assessment tool that included a 25-point checklist and a graded overall global rating scale (GRS) on a 5-point Likert scale with 8 parameters. Self-assessment using the GRS was performed by 20 trainees. Reliability and construct validity were evaluated. RESULTS Ninety-two trainees were assessed. There was excellent agreement between assessors on 21 of the 25 items, with 2 items found not to be relevant for the bench-top model. Graders agreed that the checklist was prohibitively cumbersome to use. Scores on the global assessments correlated with experience and were higher for the senior trainees, with median global summary scores increasing by postgraduate year. Reliability was confirmed through interrater correlation and internal consistency. Internal consistency was 0.92 for the GRS. There was poor correlation between grades given by the expert observers and the self-assessment from the trainee, but good correlation between scores assigned by faculty. Assessment of appropriate hemostasis was poor, which likely reflects the difficulty of evaluating this parameter in the current inanimate model. CONCLUSIONS Performance on an open simulation model evaluated by a standardized global rating scale correlated to trainee experience level. This initial work confirms the ease and applicability of the grading tool among multiple expert observers and different platforms, and supports additional; research into applications translating this performance into the operating room.

Kinematics effectively delineate accomplished users of endovascular robotics with a physical training model

OBJECTIVE Endovascular robotics systems, now approved for clinical use in the United States and Europe, are seeing rapid growth in interest. Determining who has sufficient expertise for safe and effective clinical use remains elusive. Our aim was to analyze performance on a robotic platform to determine what defines an expert user. METHODS During three sessions, 21 subjects with a range of endovascular expertise and endovascular robotic experience (novices <2 hours to moderate-extensive experience with >20 hours) performed four tasks on a training model. All participants completed a 2-hour training session on the robot by a certified instructor. Completion times, global rating scores, and motion metrics were collected to assess performance. Electromagnetic tracking was used to capture and to analyze catheter tip motion. Motion analysis was based on derivations of speed and position including spectral arc length and total number of submovements (inversely proportional to proficiency of motion) and duration of submovements (directly proportional to proficiency). RESULTS Ninety-eight percent of competent subjects successfully completed the tasks within the given time, whereas 91% of noncompetent subjects were successful. There was no significant difference in completion times between competent and noncompetent users except for the posterior branch (151 s:105 s; P = .01). The competent users had more efficient motion as evidenced by statistically significant differences in the metrics of motion analysis. Users with >20 hours of experience performed significantly better than those newer to the system, independent of prior endovascular experience. CONCLUSIONS This study demonstrates that motion-based metrics can differentiate novice from trained users of flexible robotics systems for basic endovascular tasks. Efficiency of catheter movement, consistency of performance, and learning curves may help identify users who are sufficiently trained for safe clinical use of the system. This work will help identify the learning curve and specific movements that translate to expert robotic navigation.