Adeline Schwein

Flexible robotics with electromagnetic tracking improves safety and efficiency during in vitro endovascular navigation

Objective: One limitation of the use of robotic catheters is the lack of real‐time three‐dimensional (3D) localization and position updating: they are still navigated based on two‐dimensional (2D) X‐ray fluoroscopic projection images. Our goal was to evaluate whether incorporating an electromagnetic (EM) sensor on a robotic catheter tip could improve endovascular navigation. Methods: Six users were tasked to navigate using a robotic catheter with incorporated EM sensors in an aortic aneurysm phantom. All users cannulated two anatomic targets (left renal artery and posterior “gate”) using four visualization modes: (1) standard fluoroscopy mode (control), (2) 2D fluoroscopy mode showing real‐time virtual catheter orientation from EM tracking, (3) 3D model of the phantom with anteroposterior and endoluminal view, and (4) 3D model with anteroposterior and lateral view. Standard X‐ray fluoroscopy was always available. Cannulation and fluoroscopy times were noted for every mode. 3D positions of the EM tip sensor were recorded at 4 Hz to establish kinematic metrics. Results: The EM sensor‐incorporated catheter navigated as expected according to all users. The success rate for cannulation was 100%. For the posterior gate target, mean cannulation times in minutes:seconds were 8:12, 4:19, 4:29, and 3:09, respectively, for modes 1, 2, 3 and 4 (P = .013), and mean fluoroscopy times were 274, 20, 29, and 2 seconds, respectively (P = .001). 3D path lengths, spectral arc length, root mean dimensionless jerk, and number of submovements were significantly improved when EM tracking was used (P < .05), showing higher quality of catheter movement with EM navigation. Conclusions: The EM tracked robotic catheter allowed better real‐time 3D orientation, facilitating navigation, with a reduction in cannulation and fluoroscopy times and improvement of motion consistency and efficiency. Clinical Relevance: We show here how the combination of robotic endovascular navigation and electromagnetic tracking system has the potential to improve procedural safety and efficacy and to lead toward “fluoroscopy‐free” endovascular surgery.

Gender Related Long-Term Differences After Open Infrainguinal Surgery for Critical Limb Ischemia

OBJECTIVE The role of gender on long-term infrainguinal open surgery outcomes still remains uncertain in critical limb ischemia patients. The aim of this study is to evaluate the gender-specific differences in patient characteristics and long-term clinical outcomes in terms of survival, primary patency and limb salvage among patients undergoing infrainguinal open surgery for CLI. MATERIAL AND METHODS All consecutive patients undergoing infrainguinal open surgery for critical limb ischemia between 2003 and 2012 were included. Survival, limb salvage and primary patency rates were assessed. Independent outcome determinants were identified by the Cox proportional hazard ratio using age and gender as adjustment factors. RESULTS 584 patients (269 women and 315 men, mean age 76 and 71 years respectively) underwent 658 infrainguinal open surgery (313 in women and 345 in men). Survival rate at 6 years was lower among women compared to men with 53.5% vs 70.9% (p < 0.001). The same applied to primary patency (35.9% vs 52.4%, p < 0.001) and limb salvage (54.3% vs 81.1%, p < 0.001) at 6 years. Female-gender was an independent factor predicting death (hazard ratio 1.50), thrombosis (hazard ratio 2.37) and limb loss (hazard ratio 7.05) in age and gender-adjusted analysis. CONCLUSION Gender-related disparity in critical limb ischemia open surgical revascularization outcomes still remains.

Treatment of Aneurysmal Aberrant Right Subclavian Artery with Triple-Barrel Stent Graft

Aneurysmal evolution of an aberrant right subclavian artery (ARSA) is an operative indication. Endovascular treatment is a minimally invasive procedure, which offers good short-term and midterm results. We describe a case of a 9-cm diameter ARSA aneurysm in a symptomatic man, treated with the triple-barrel technique using a thoracic aortic stent graft combined with surgical and endovascular revascularization of the supra-aortic trunks. Postoperatively, the patient developed a type III endoleak which was covered. The triple-barrel technique has been a proposed treatment approach for complex aortic arch pathologies and remains a less invasive option when compared with open surgery.

Feasibility of three-dimensional magnetic resonance angiography-fluoroscopy image fusion technique in guiding complex endovascular aortic procedures in patients with renal insufficiency

Objective: Three‐dimensional image fusion of preoperative computed tomography (CT) angiography with fluoroscopy using intraoperative noncontrast cone‐beam CT (CBCT) has been shown to improve endovascular procedures by reducing procedure length, radiation dose, and contrast media volume. However, patients with a contraindication to CT angiography (renal insufficiency, iodinated contrast allergy) may not benefit from this image fusion technique. The primary objective of this study was to evaluate the feasibility of magnetic resonance angiography (MRA) and fluoroscopy image fusion using noncontrast CBCT as a guidance tool during complex endovascular aortic procedures, especially in patients with renal insufficiency. Methods: All endovascular aortic procedures done under MRA image fusion guidance at a single‐center were retrospectively reviewed. The patients had moderate to severe renal insufficiency and underwent diagnostic contrast‐enhanced magnetic resonance imaging after gadolinium or ferumoxytol injection. Relevant vascular landmarks electronically marked in MRA images were overlaid on real‐time two‐dimensional fluoroscopy for image guidance, after image fusion with noncontrast intraoperative CBCT. Technical success, time for image registration, procedure time, fluoroscopy time, number of digital subtraction angiography (DSA) acquisitions before stent deployment or vessel catheterization, and renal function before and after the procedure were recorded. The image fusion accuracy was qualitatively evaluated on a binary scale by three physicians after review of image data showing virtual landmarks from MRA on fluoroscopy. Results: Between November 2012 and March 2016, 10 patients underwent endovascular procedures for aortoiliac aneurysmal disease or aortic dissection using MRA image fusion guidance. All procedures were technically successful. A paired t‐test analysis showed no difference between preimaging and postoperative renal function (P = .6). The mean time required for MRA‐CBCT image fusion was 4:09 ± 01:31 min:sec. Total fluoroscopy time was 20.1 ± 6.9 minutes. Five of 10 patients (50%) underwent stent graft deployment without any predeployment DSA acquisition. Three of six vessels (50%) were cannulated under image fusion guidance without any precannulation DSA runs, and the remaining vessels were cannulated after one planning DSA acquisition. Qualitative evaluation showed 14 of 22 virtual landmarks (63.6%) from MRA overlaid on fluoroscopy were completely accurate, without the need for adjustment. Five of eight incorrect virtual landmarks (iliac and visceral arteries) resulted from vessel deformation caused by endovascular devices. Conclusions: Ferumoxytol or gadolinium‐enhanced MRA imaging and image fusion with fluoroscopy using noncontrast CBCT is feasible and allows patients with renal insufficiency to benefit from optimal guidance during complex endovascular aortic procedures, while preserving their residual renal function.

Promising Results of the Forearm Basilic Fistula Reveal a Worthwhile Option between Radial Cephalic and Brachial Fistula.

BACKGROUND Use of the forearm basilic vein for the creation of an arteriovenous fistula has been codified as second-choice vascular access for hemodialysis in the last clinical guidelines of the Society for Vascular Surgery in 2008. Poor literature data on this technical option and on its evaluation and outcomes led us to initiate a retrospective single-center study. METHODS We analyzed the outcomes of every arteriovenous fistula using the forearm basilic vein created in our department. It is a retrospective study in which we collected data prospectively by contacting dialysis centers, nephrologists, and patients. Primary end point was primary patency rate at 1 year. Secondary end points were secondary patency rate at 1 year, time of maturation, and Doppler flow measurement before the first puncture. RESULTS From February 2004 to June 2014, 49 forearm basilic arteriovenous fistulas were created: 33 ulnar-basilic and 16 radial basilic arteriovenous fistulas. Initial technical success rate was 98%. Functional success rate was 60%. Primary and secondary patency rates at 1 year were respectively 21% and 48%. Median time of maturation was 81 days, and mean Doppler flow measurement was 678 mL/min. Ulnar-basilic fistulas had a statistically significant shorter time of maturation than radial basilic fistulas (P ≤ 0.05). CONCLUSIONS Despite poor primary patency rate and a long time of maturation, forearm basilic arteriovenous fistula has satisfactory secondary patency rate and keeps all the advantages of a distal-located vascular access concerning complications. It is worth its second-choice place in the current algorithm of creation of vascular access for hemodialysis.

Robotic-Assisted Inferior Vena Cava Filter Retrieval

Although anticoagulation remains the mainstay of therapy for patients with venous thromboembolism, guidelines recommend the use of inferior vena cava (IVC) filters in those who fail anticoagulation or have contraindications to its use. Short-term use of filters has proven effective in reducing the rate of pulmonary embolism. However, their extended use is associated with a variety of complications such as thrombosis, filter migration, or caval perforation, thus making a case for timely filter retrieval. This is the case of a 68-year-old female with a history of chronic oral anticoagulation use for multiple deep venous thrombi (DVT) and pulmonary emboli (PE) who required cervical and thoracic spinal intervention for spondylosis and foramina stenosis. Given her increased risk of recurrent DVT and PE perioperatively, we elected to place a Cook Celect™ IVC filter (Cook Medical, Bloomington, IN) after oral anticoagulation was stopped for the procedure. Her treatment course was prolonged due to wound-healing complications. We elected to use the Magellan Robotic Catheter System (Hansen Medical, Mountain View, CA) for filter retrieval when she presented 6 months later with caval perforation from the filter struts. With its ease of use, superior mechanical stability, and maneuverability, robot-assisted IVC filter retrieval may be a safer and more reliable substitute for traditional navigation techniques when presented with challenging filter retrievals.

Electromagnetic tracking of flexible robotic catheters enables “assisted navigation” and brings automation to endovascular navigation in an in vitro study

Objective: Combining three‐dimensional (3D) catheter control with electromagnetic (EM) tracking‐based navigation significantly reduced fluoroscopy time and improved robotic catheter movement quality in a previous in vitro pilot study. The aim of this study was to expound on previous results and to expand the value of EM tracking with a novel feature, assisted navigation, allowing automatic catheter orientation and semiautomatic vessel cannulation. Methods: Eighteen users navigated a robotic catheter in an aortic aneurysm phantom using an EM guidewire and a modified 9F robotic catheter with EM sensors at the tip of both leader and sheath. All users cannulated two targets, the left renal artery and posterior gate, using four visualization modes: (1) Standard fluoroscopy (control). (2) 2D biplane fluoroscopy showing real‐time virtual catheter localization and orientation from EM tracking. (3) 2D biplane fluoroscopy with novel EM assisted navigation allowing the user to define the target vessel. The robotic catheter orients itself automatically toward the target; the user then only needs to advance the guidewire following this predefined optimized path to catheterize the vessel. Then, while advancing the catheter over the wire, the assisted navigation automatically modifies catheter bending and rotation in order to ensure smooth progression, avoiding loss of wire access. (4) Virtual 3D representation of the phantom showing real‐time virtual catheter localization and orientation. Standard fluoroscopy was always available; cannulation and fluoroscopy times were noted for every mode and target cannulation. Quality of catheter movement was assessed by measuring the number of submovements of the catheter using the 3D coordinates of the EM sensors. A t‐test was used to compare the standard fluoroscopy mode against EM tracking modes. Results: EM tracking significantly reduced the mean fluoroscopy time (P < .001) and the number of submovements (P < .02) for both cannulation tasks. For the posterior gate, mean cannulation time was also significantly reduced when using EM tracking (P < .001). The use of novel EM assisted navigation feature (mode 3) showed further reduced cannulation time for the posterior gate (P = .002) and improved quality of catheter movement for the left renal artery cannulation (P = .021). Conclusions: These results confirmed the findings of a prior study that highlighted the value of combining 3D robotic catheter control and 3D navigation to improve safety and efficiency of endovascular procedures. The novel EM assisted navigation feature augments the robotic master/slave concept with automated catheter orientation toward the target and shows promising results in reducing procedure time and improving catheter motion quality. Clinical Relevance: We show in this study how the combination of robotic endovascular navigation and an electromagnetic tracking system has the potential to improve procedural safety and efficacy and to lead toward “fluoroscopy‐free” endovascular surgery.

Computed tomography angiography-fluoroscopy image fusion allows visceral vessel cannulation without angiography during fenestrated endovascular aneurysm repair

Background: Fenestrated endovascular aneurysm repair (FEVAR) is an evolving technique to treat juxtarenal abdominal aortic aneurysms (AAAs). Catheterization of visceral and renal vessels after the deployment of the fenestrated main body device is often challenging, usually requiring additional fluoroscopy and multiple digital subtraction angiograms. The aim of this study was to assess the clinical utility and accuracy of a computed tomography angiography (CTA)‐fluoroscopy image fusion technique in guiding visceral vessel cannulation during FEVAR. Methods: Between August 2014 and September 2016, all consecutive patients who underwent FEVAR at our institution using image fusion guidance were included. Preoperative CTA images were fused with intraoperative fluoroscopy after coregistering with non‐contrast‐enhanced cone beam computed tomography (syngo 3D3D image fusion; Siemens Healthcare, Forchheim, Germany). The ostia of the visceral vessels were electronically marked on CTA images (syngo iGuide Toolbox) and overlaid on live fluoroscopy to guide vessel cannulation after fenestrated device deployment. Clinical utility of image fusion was evaluated by assessing the number of dedicated angiograms required for each visceral or renal vessel cannulation and the use of optimized C‐arm angulation. Accuracy of image fusion was evaluated from video recordings by three raters using a binary qualitative assessment scale. Results: A total of 26 patients (17 men; mean age, 73.8 years) underwent FEVAR during the study period for juxtarenal AAA (17), pararenal AAA (6), and thoracoabdominal aortic aneurysm (3). Video recordings of fluoroscopy from 19 cases were available for review and assessment. A total of 46 vessels were cannulated; 38 of 46 (83%) of these vessels were cannulated without angiography but based only on image fusion guidance: 9 of 11 superior mesenteric artery cannulations and 29 of 35 renal artery cannulations. Binary qualitative assessment showed that 90% (36/40) of the virtual ostia overlaid on live fluoroscopy were accurate. Optimized C‐arm angulations were achieved in 35% of vessel cannulations (0/9 for superior mesenteric artery cannulation, 12/25 for renal arteries). Conclusions: Preoperative CTA‐fluoroscopy image fusion guidance during FEVAR is a valuable and accurate tool that allows visceral and renal vessel cannulation without the need of dedicated angiograms, thus avoiding additional injection of contrast material and radiation exposure. Further refinements, such as accounting for device‐induced aortic deformation and automating the image fusion workflow, will bolster this technology toward optimal routine clinical use.

PC210. Magnetic Resonance Imaging Characterization of Chronic Pathologic Changes in a Swine Model of Central Venous Thrombosis

Author Disclosures: C. Z. Abraham: Nothing to disclose; E. Jung: Nothing to disclose; J. Kaufman: Bio2 Medical: Consulting fees (eg, advisory boards), Ownership Interest, Cook Medical: Consulting fees (eg, advisory boards), Novate Medical: Consulting fees (eg, advisory boards); G. J. Landry: Nothing to disclose; T. K. Liem: Nothing to disclose; E. L. Mitchell: Nothing to disclose; G. L. Moneta: Nothing to disclose.

Commentary on “A Feasibility Study of a New Unibody Branched Stent Graft Applied to Reconstruct the Canine Aortic Arch”

In their paper, Li et al. have presented a new device for treating thoracic aortic pathologies involving the arch, which has demonstrated promising results on a canine model in terms of feasibility and ease of deployment. Aortic arch device development is currently a major research topic for innovative designs to meet the challenges of treatment in this area: mainly the risk of stroke and patient specific complex 3D anatomy. The ideal device should feature conformability, simplicity of deployment, durability, low profile delivery system, and shortand longterm safety. The last point is extremely important because of the major displacements and stresses applied to the arch and supra-aortic trunks (SAT) during the cardiac cycle. The branched thoracic stent graft design can be categorised into two configurations: modular (assembled in vivo) and unibody (implanted as a whole) devices. Usually, modular devices consist of a main body with inner or small outer branches acting as landing zones for bridging stents connected to the SAT. Only this configuration has been evaluated in clinical practice. Spear et al. published mid-term results of a double branched thoracic device in 27 patients, showing 100% technical success rate, 30 day and 1 year mortality rates of 0% and 3.7%, respectively, 30 day and 1 year secondary intervention of 14.8% and 22.2%, respectively, and 30 day stroke rate of 11.1%. Although modular devices offer increased maneuverability for navigation and positioning, highly stressed bridging stents are theoretically at more risk for disconnection over time. Thus, Li et al. developed unibody branched stent grafts as initially proposed by Dr. Inoue. The branches are sewn to the aortic body, which should theoretically offer greater durability and safety over time. They developed an ingenious delivery system to make deployment easier. However, delivering the stent graft requires multiple manoeuvres with the potential to cause lesions of the arterial luminal surface and to dislodge atheromatous debris in pathological human aortas.