Alexander Rolls

Robot-assisted Fenestrated Endovascular Aneurysm Repair (FEVAR) Using the Magellan System

A 67-year-old man underwent robot-assisted three-vessel fenestrated endovascular aneurysm repair (FEVAR) for a 7.3-cm juxtarenal aneurysm. The 6-F robotic catheter was manipulated from a remote workstation, away from the radiation source. Robotic cannulation of the left renal artery was achieved within 3 minutes. System setup time was 5 minutes. There were no postoperative complications. Computed tomography angiography performed at discharge and at 4-month follow-up confirmed target vessel patency with no evidence of an endoleak. Selective cannulation of target vessels during FEVAR using this novel technology is feasible. Endovascular robotics may have a role in simplifying complex endovascular tasks and potentially reducing radiation exposure to the operator.

A Pilot Study of Video-motion Analysis in Endovascular Surgery: Development of Real-time Discriminatory Skill Metrics

OBJECTIVES Accurate assessment and credentialing of physicians is essential. Objective motion analysis of guide-wire/catheter manipulation to assess proficiency during endovascular interventions remains unexplored. This study aims to assess its feasibility and its role in evaluation of technical ability. MATERIALS AND METHODS A semi-automated catheter-tracking software was developed which allows for frame-by-frame motion analysis of fluoroscopic videos and calculation 2D catheter tip path-length. 21 interventionalists (6 cardiologists, 8 interventional radiologists, 7 vascular surgeons; 14/21 had performed >500 endovascular procedures) performed an identical carotid artery stenting procedure (CAS) on a VIST simulator (Mentice, Gothenburg, Sweden). Operators were sub-divided into four categories according to CAS experience: 6 inexperienced (0 CAS-group A), 3 low-volume (1-20 CAS-group B), 5 moderate-volume (21-50 CAS-group C) and 7 high-volume (>50 CAS-group D) CAS experience. Total PL was calculated for each case and comparisons made between groups. PL was correlated with: quantitative, simulator-derived metrics and qualitative performance scores (generic and procedure-specific) derived from post-hoc video analysis by three blinded observers. RESULTS Group D used 5160.3 (inter-quartile range- IQR 4046.4-7142.9) pixels of movement, compared to 6856.7 (5914.4-8106.9) for group A (p = 0.046); 10,905.1 (7851.1-14,381.5) for group B (p = 0.017); and 9482.6 (8663.5-13,847.6) for group C (p = 0.003). Statistically significant inverse correlations were seen between total PL and qualitative performance scores (rho = -0.519 for generic (p = 0.027) rho = -0.567 for procedure-specific (p = 0.014) scores). PL did not correlate with any of the simulator-derived metrics (errors, contrast volume, total procedure and fluoroscopy times, cine-loops used). CONCLUSION Endovascular instrument video motion analysis is feasible and may represent a valuable tool for the objective assessment of endovascular skill.

Robot-Assisted Uterine Artery Embolization: A First-in-Woman Safety Evaluation of the Magellan System

PURPOSE To provide a technical description of robot-assisted uterine artery embolization and to investigate the safety and feasibility of the Magellan (Hansen Medical, Mountain View, California, USA) robotic catheter in this complex arterial bed. MATERIALS AND METHODS Five women (mean age, 48.8 y) underwent robot-assisted bilateral uterine artery embolization over a 10-month period using the Magellan robotic catheter. Demographic, clinicopathologic, and endovascular performance metric data (fluoroscopy and cannulation times) were recorded as well as short-term outcomes. RESULTS Robotic cannulation of bilateral internal iliac and uterine arteries was successful in all cases. Median right and left internal iliac artery cannulation and total fluoroscopy times were 3 minutes (interquartile range [IQR], 1.5-4 min), 2 minutes (IQR, 1.5-4 min), and 11 minutes (IQR, 9.5-14 min). Median right and left uterine artery cannulation times were both 11 minutes (IQR, 6.5-15 min and 8-12 min, respectively). Technical success was 100%. All patients were discharged on postoperative day 1, and there were no major or access site complications. At 6 months after the procedure, all patients reported significant improvement of symptoms, with a median increase in health-related quality-of-life score of 58% (48.5%-61.75%). CONCLUSIONS The use of the new-generation Magellan system in uterine artery embolization is feasible and appears to be safe. The additional navigational capability and added maneuverability of the NorthStar catheter (Hansen Medical, Mountain View, California) may facilitate selective catheterization of small iliac artery divisions and may be useful in any procedure where complex arterial selection is needed.

Experience with a novel custom-made fenestrated stent graft in the repair of juxtarenal and type IV thoracoabdominal aneurysms

OBJECTIVE Fenestrated stent grafting has become increasingly popular as a means to manage complex aortic pathology, including juxta- and pararenal aneurysms. The design of a recently developed custom-made fenestrated stent graft, in theory, confers advantages when managing anatomically challenging aortic morphology. This study evaluated its feasibility in anatomically challenging scenarios. METHODS Over a 12-month period, 20 patients received fenestrated stent grafts. Among those, 13 patients with juxtarenal or type IV thoracoabdominal aortic aneurysms underwent endovascular repair with the novel fenestrated stent graft at a single UK institution. Data on aneurysm morphology and immediate and short-term results were collected prospectively. RESULTS The mean aneurysmal sac size was 7.3 cm (range, 5.5-10.0 cm). The mean infrarenal neck length was 4.4 mm (range, 0-9 mm), and in three cases was lined by a pre-existing infrarenal stent graft. Nine cases had an infrarenal neck angulation of 60(°) or more in either the anteroposterior or coronal planes. Five cases had ≥50% thrombus at the proximal landing zone. A total of 35 target vessels were cannulated, of which six right renal and four left renal arteries were angulated ≥120(°). Two-thirds of cannulated celiac trunks were angulated ≥120(°), and one cannulated superior mesenteric artery was angulated ≥ 140(°). Seven of the cannulated targets were stenosed more than 60%. One patient had two right renal arteries arising 3 mm from each other. Four right and four left common iliac arteries were angulated ≥90(°) in relation to the infrarenal aorta. Technical success was 100%. Median time from date of procedure to most recent follow-up with computed tomography scanning was 33 weeks. There was no type I or III endoleak. One type II endoleak was observed at the time of most recent computed tomography scanning and treated expectantly. There was a single incident of left renal artery occlusion. One patient required repair of a brachial artery, fasciotomies, and temporary haemofiltration. One patient died from ischemic heart disease 77 weeks after the procedure. CONCLUSIONS The use of the novel fenestrated stent graft system in patients with hostile aortic aneurysmal morphology is feasible with acceptable short-term outcomes.

Robust Catheter and Guidewire Tracking Using B-Spline Tube Model and Pixel-Wise Posteriors

In endovascular surgery and cardiology, robotic catheters are emerging as a promising technology for enhanced catheter manipulation and navigation while reducing radiation exposure. For robotic catheter systems especially with tendon actuation, a key challenge is the localisation of the catheter shape and position within the anatomy. An effective approach is through image-based catheter/guidewire detection and tracking. However, these are difficult problems due to the thin appearance of the instruments in the image and the low signal-to-noise ratio of fluoroscopy. In this letter, we propose a deformable B-spline tube model, which can effectively represent the shape of a catheter and guidewire. The model allows fitting using a region-based probabilistic algorithm, which does not rely on intensity gradients but exploits a signed distance function and the nonparametric distributions of measurements. Unlike previous B-spline fitting approaches, which optimise the spline with respect to control points, we propose a knot-driven scheme with an equidistance prior to better fit complex curves. Our probabilistic framework shows promising results for catheter and guidewire tracking in different procedures even with handling overlapping instrument segments. We present empirical studies using phantom model data and in vivo fluoroscopic sequences with annotated ground truth. Our results indicate that the proposed approach can precisely model the catheter and guidewire contours in near real time, and this information can be embedded in a robotic catheter control loop or utilised for image-guidance.

Catheter manipulation analysis for objective performance and technical skills assessment in transcatheter aortic valve implantation

PurposeTranscatheter aortic valve implantation (TAVI) demands precise and efficient handling of surgical instruments within the confines of the aortic anatomy. Operational performance and dexterous skills are critical for patient safety, and objective methods are assessed with a number of manipulation features, derived from the kinematic analysis of the catheter/guidewire in fluoroscopy video sequences.MethodsA silicon phantom model of a type I aortic arch was used for this study. Twelve endovascular surgeons, divided into two experience groups, experts (

A Survey on the Current Status and Future Challenges Towards Objective Skills Assessment in Endovascular Surgery

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Future Technology and Customized Solutions for Endoaortic Surgery

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