Endovascular Tools Research Articles

Navigating between the science and art of acute limb ischemia treatment

The diagnosis and treatment of acute limb ischemia (ALI) has long been a fierce adversary that has evolved over the last several decades with scientific advancements in endovascular therapy.History and physical examination remain the mainstay of diagnosis enhanced by detailed imaging to guide therapy. Many endovascular tools are available for prompt restoration of flow that compliment traditional surgical options. These devices incorporate the mechanical removal of thrombus and the chemical dissolution of thrombus . Medical decision-making for ALI patients must take into account the patient characteristics, anatomic variables, mechanism of ischemia, degree of ischemia, and operator skill to employ the right strategy for the right patient. This moving target challenges scientific study, making the therapeutic bedside decision making an artform. We present an overview of the field, supportive data, and a treatment algorithm that hopefully captures this delicate balance.

Intervention for symptomatic vertebrobasilar disease.

Disease of the vertebral (VA) and basilar arteries (BA) can lead to stroke of the posterior circulation and may warrant management strategies which differ from the anterior circulation. The mechanism and location of the disease determine its natural history and therefore affect the relative risks and benefits of the possible treatment options. Vertebrobasilar (VB) atherosclerotic disease is a source of both hemodynamic and embolic posterior circulation stroke. Advances in medical therapy have decreased the rate of stroke after initial symptomatic presentation. Antiplatelet therapy, blood pressure control, and optimization of secondary risk factors can reduce recurrent stroke risk in both intracranial and extracranial VB disease. However, symptomatic intracranial disease is still associated with a high risk of subsequent stroke, particularly those with hemodynamic compromise who represent a higher risk population. Patients with hemodynamic impairment may benefit from judicious application of endovascular and microsurgical interventions to augment blood flow. Stenting, angioplasty alone, bypass surgery, and endarterectomy, represent endovascular and surgical tools available to address medically refractory VB disease. Apart from atherosclerotic disease, dissection is another etiology of VB stroke, most frequently affecting the extracranial VA. Treatment is predominantly antithrombotic therapy although surgical or endovascular intervention can be required in rare cases of persistent embolism or hemodynamic compromise. In contrast, extrinsic compromise of the VA represents a separate extracranial pathology and is best treated with mechanistically targeted surgeries or extracranial bypass.

Endovascular management of giant visceral artery aneurysms

Endovascular management of small visceral artery aneurysms is an established treatment with satisfactory outcomes. However, when size exceeds 5 cm visceral aneurysms are considered as “giant” (giant visceral artery aneurysms or GVAAs) and management is significantly more complex. Between August 2007 and June 2019 eleven cases of GVAAs that were endovascularly treated were retrospectively reviewed and included in this single center study. Mean size was 80 mm (± 26.3 mm) x 46 mm (+ \\-11.8 mm). Nine of the lesions were true aneurysms, and two were pseudoaneurysms. In 8 patients, the lesion was causing compression symptoms in the surrounding organs, one patient developed a contained rupture while 2 patients were completely asymptomatic. However, all patients were hemodynamically stable at the time of treatment. Technical success was defined as immediate complete exclusion of the aneurysmal sac, and clinical success as complete relief from clinical symptoms. Follow-up was performed with CT angiography, ultrasound and clinical examination. Mean follow-up was 45 months (range 6–84). Technical and clinical success were both 91%. Complications were one lack of control of contained rupture that was subsequently operated, one case of self-limiting non-target spleen embolization and one case of splenic abscess. Three patients died, one due to the contained rupture 15 days after procedure, the other two for other causes and occurred during the long-term follow-up. This series suggests that endovascular treatment of giant visceral artery aneurysms and pseudoaneuryms is a valid minimally invasive solution with very satisfactory immediate and long-term outcomes unless the aneurysm is already ruptured. A variety of endovascular tools may be required for successful treatment.

Initial experience with the CatchView thrombectomy device for acute ischemic stroke

BackgroundWe report our initial experience with the CatchView (CV) thrombectomy device in patients with acute ischemic stroke (AIS).MethodsA retrospective analysis of 53 of 284 AIS patients (mean age 66.6±14.8 years,...

Numerical simulation of fenestrated graft deployment: Anticipation of stent graft and vascular structure adequacy.

Fenestrated endovascular aneurism repair (FEVAR) is a minimally invasive technique, and its success depends on the adequacy of the correspondence between the visceral arteries ostia and position of the fenestrations of the stent graft (SG) during its deployment in juxtarenal aneurisms. However, the fenestration position is generally determined from a preoperative computerised tomography (CT) scan, without considering the vascular deformation induced by the insertion of the endovascular tools. Catheterisation difficulties may occur during clinical procedures. Accordingly, the objective of this work is to present an initial proof of concept aimed at anticipating and optimising the position of the fenestrations, while considering the vascular deformation induced by the insertion of the endovascular tools. The proposed method relies on the finite element method to simulate the SG deployment in a vascular structure (VS), and considers the vascular deformation induced by the tools. After determining the optimal simulation parameters for a patient-specific case, the robustness of the method is demonstrated on six other representative anatomies. The simulated SG is also compared with post-deployment CT observations, and demonstrates good adequacy. The results show that the numerically corrected fenestration positions, as determined from the simulated results following the insertion of the endovascular tools, deviate from those of the standard plan (as determined from the preoperative CT scan). This indicates that the SG-VS adequacy could be improved via simulation-based planning, to anticipate potential catheterisation difficulties.

Localization of endovascular tools in X-ray images using a motorized C-arm: visualization on HoloLens

Abstract C-arms are medical devices widely used for image-guided minimally invasive endovascular procedures. This technology requires considerable experience for the physicians to position the C-arm to obtain X-ray images of the endovascular tools. In addition, this image-guided therapy is based on two-dimensional images which lack depth information. The purpose of this study was to develop a system that controls the C-arm movements based on the previous position of the tip of a guide wire and the vessel information, and also displays the estimated tip position (specifically, the virtual line that would join the X-ray source and the projected tip in the flat-panel detector) on an augmented reality device (HoloLens). A phantom study was conducted to evaluate the system using intraoperative cone-beam computed tomography scans to obtain the reference tip position. The mean distance between the tip position (ground truth) and the virtual three-dimensional line was 1.18 mm. The proposed system was able to control the C-arm movements based on the position of the tip of the guide wire. The visualization on HoloLens also allowed a more intuitive understanding of the position of the endovascular tool related to the patient’s anatomy during the intervention.

Catheter pose-dependent virtual angioscopy images for endovascular aortic repair: validation with a video graphics array (VGA) camera

Abstract Previous research reported catheter pose-dependent virtual angioscopy images for endovascular aortic repair (EVAR) (phantom studies) without any validation with video images. The goal of our study focused on conducting this validation using a video graphics array (VGA) camera. The spatial relationship between the coordinate system of the virtual camera and the VGA camera was computed with a Hand-Eye calibration so that both cameras produced similar images. A re-projection error of 3.18 pixels for the virtual camera and 2.14 pixels for the VGA camera was obtained with a designed three-dimensional (3D) printed chessboard. Similar images of the vessel (3D printed aorta) were acquired with both cameras except for the different depth. Virtual angioscopy images provide information from inside the vessel that may facilitate the understanding of the tip position of the endovascular tools while performing EVAR.

Intercostal artery embolization to induce false lumen thrombosis in type B aortic dissection.

Persistent false lumen flow is common after thoracic endovascular aortic repair of type B aortic dissection and may contribute to continued aortic aneurysmal degeneration. We report an innovative technique of intercostal artery embolization within the false lumen for a patient who had incomplete false lumen thrombosis and progressive aortic enlargement after thoracic endovascular aortic repair of chronic type B aortic dissection. Technical success was facilitated by use of on-table cone beam computed tomography angiography, virtual vessel marking, and modern endovascular tools. The patient had no complications from the procedure. Postoperative imaging demonstrated complete thoracic false lumen thrombosis and favorable aortic remodeling with reduction in maximal aortic diameter.

Emergency endovascular treatments for delayed hemorrhage after pancreaticobiliary surgery: indications, outcomes, and follow-up of a retrospective cohort.

To evaluate the outcomes of emergency endovascular treatments for delayed bleeding after pancreaticobiliary surgery. We retrospectively evaluated 21 patients (M:F = 13:8, median age = 64years) undergoing 23 endovascular treatments, performed from 2010 to 2017 in a single center. Data collected were patient characteristics; surgery; pathology; incidence of postoperative pancreatic fistulas (POPF); bleeding signs on CT and angiography; damaged artery; endovascular tools used; technical and clinical success; intervals between surgery, endovascular treatment, and discharge; survival rates. Sixteen patients had pancreatoduodenectomy, three hepaticojejunostomy, two distal pancreatectomy. Indications for surgery were mainly biliary (33%), pancreatic (19%), or duodenal (10%) malignancies. Seventeen patients had "grade C" POPF, three suffered a biliary leak, one had no POPF. Active bleeding was present in 17/23 CTs and in 22/23 angiographies, mostly from hepatic (43%), gastroduodenal (22%), and splenic (13%) arteries. The endovascular treatments were performed with coils (26%), glue (22%), stent-graft (22%), and their combinations (30%). Sixteen patients had a single endovascular treatment, one underwent a second embolization, three had subsequent surgery, one had repeat embolization followed by surgery. Relaparotomy rate was 19%. Median hospital stay was 37days (range 12-75); median intervals among pancreaticobiliary surgery, endovascular treatment, and discharge were 21 (2-36) and 12 (8-47) days, respectively. We observed 4/21 intrahospital deaths (median: 31days from endovascular treatment, 4-53); 1-year survival rate of discharged patients was 71%. Endovascular treatment using embolization and/or stent-graft placement is a useful first-line intervention to halt postoperative hemorrhage after pancreaticobiliary surgery and decreases the need for urgent relaparotomy.

Experimental Visualization of Vascular Structures with Microsoft Hololens – Set-Up for Navigated Contrast Agent and Radiation-Sparing Endovascular Procedures (NAV-CARS EVAR)

Introduction - Over the last two decades, endovascular therapy has become an integral part of vascular surgery. One of the most difficulty in learning and performing this minimally invasive therapy is the fact, the vascular surgeon has to mentally overlay the three-dimensional vascular tree with the two-dimensional angiographic scene. While endovascular techniques are improving, the imaging during the procedure is still dependent on contrast agents and X-Rays with their known disadvantages. Looking at actual development trends towards radiation free localization of endovascular tools, the visualization and proper integration of this spatial information will become a key technology. Methods - We report the development of a real-time navigation software, which allows a three-dimensional view of the vascular system without any need of radiation. We used a vascular phantom model (Blue phantom FAST Trauma Full Torso Ultrasound Training Model) and an augmented reality (AR) headset (Microsoft HoloLens) to display the vascular structures in the field of view of the surgeon. Using simple landmark-based surface registration of a CT scan and marching cubes segmentation of the vessel tree, it is straightforward to visualize both the surface and the vessels in the AR display. Using a magnetic tracking system (i.e. AURORA, Northern Digital Inc.) it is possible to also display the position and orientation of a catheter inside the vessels. Results - Our preliminary results of the virtual real time navigation in endovascular procedures are promising. The presented technique allows a three-dimensional holographic view of the vascular system without any need of radiation. Using extrinsic landmark-based calibrations, the virtual objects are precisely aligned with the real world, resulting in a convincing holographic illusion. The prototype also offers the possibility of intervention planning and simulation, which in turn will lead to a reduced learning curve and therefore increased patient safety. Conclusion - The “virtual angioscope” may improve intraoperative visualization, placement of guide-wires and stents. It may reduce the amount of contrast agents and exposure to X-rays.

Sleeve Fistulectomy: A Novel Hybrid Technique to Manage the Degenerative Arteriovenous Fistula

Aneurysmal degeneration following long-term access is an important problem associated with an arteriovenous fistula (AVF) and can result in rupture, thrombosis, or the need for ligation. We describe five patients receiving hemodialysis through large degenerative brachiocephalic AVFs who underwent successful revision and avoided the need for a temporary dialysis catheter. A hybrid approach using an open surgical technique with both endovascular and laparoscopic tools provides an opportunity to maintain patency and restore function by combining modern surgical tools.

Angioplastie des lésions coronaires de bifurcation en 2019 : questions brûlantes ?

Coronary bifurcations are involved in 15–20% of all percutaneous coronary interventions (PCI) and remain one of the most challenging lesions in interventional cardiology in terms of procedural success rate as well as long-term cardiac events. The optimal management of bifurcation lesions is still debated but involves careful assessment, planning and a sequential provisional approach. The preferential strategy for PCI of bifurcation lesions remains to use main vessel (MV) stenting with a proximal optimisation technique (POT) and provisional side branch (SB) stenting as a preferred approach. Final kissing balloon inflation is not recommended in all cases. In the minority of lesions where two stents are required, careful deployment and optimal expansion are essential to achieve a long-term result. Intracoronary imaging techniques (IVUS, OCT) and FFR are useful endovascular tools to achieve optimal results.

Vein of Galen Malformations: The Texas Children's Hospital Experience in the Modern Endovascular Era.

Vein of Galen malformations (VOGM) comprise nearly a third of pediatric cerebrovascular anomalies, with potentially devastating neurological and systemic complications. Advances in endovascular therapies have dramatically improved outcomes compared to historical surgical treatments, and neurosurgeons are an essential component of the multidisciplinary critical care team. To retrospectively review pediatric patients with VOGM treated at Texas Children's Hospital (TCH), a quaternary referral center, over 15 yr, and present lessons learned in treating children with modern endovascular techniques. Charts from TCH were retrospectively reviewed for the past 15 yr. Patients with diagnosis including "Vein of Galen," "Vein of Galen malformation," "Vein of Galen aneurysmal malformation," or any abbreviations (ie, VOG, VOGM, VOGAM) were reviewed. Presentation, imaging, treatment specifics, and clinical outcomes were reported. There were 18 patients with VOGM managed at TCH from 2002 to 2018 with a total of 29 embolizations. Seventeen were performed with a single embolisate (NBCA or Onyx), and 12 with a combination. A dual lumen balloon catheter was used as an adjunct in 3 embolizations. Complications occurred in 5 embolizations (24%), including hemorrhage, embolisate migration, and femoral vessel occlusion. Surviving patients were followed for a mean of 38 mo, with 12 having normal or near-normal neurological development. VOGM can present with a myriad of neurological and systemic symptoms, potentially in extremis. Neurosurgical involvement in these cases is critical, as urgent treatment can be lifesaving. Patients may require multiple treatment sessions using a variety of endovascular tools and techniques.

The Early and Mid-Term Follow-up of Drug Eluting Balloon (DEB) For Below the Knee Angioplasty: An Observational Study

AbstractBackground: Re-stenosis following infra-popliteal angi-oplasty could results in many serious consequences like recurrence of ischemic symptoms or break through of wound healing. With the evolving techniques of Paclitaxil release and the rapid advancement in the manufacturing of endovas-cular equipment, drug eluting balloons emerge as a useful option to overcome intimal hyperplasia and subsequent re-stenosis.Aim of Study: To highlight the clinical impact of additional DEB application in patients with CLI attributed to infra-popliteal disease regarding the re-stenosis rate, amputation free survival and limb salvage.Material and Methods: This study is prospective obser-vational study over a period of one year including 33 patients who underwent infra-popliteal angioplasty using DEB.Results: 33 patients (36 limbs) were included in the study, 24 cases (27 limbs) were presented by a re-stenosis or occlusion after previous trial of angioplasty using plain balloon, while 9 patients come with the first presentation (Denovo lesions). Stenotic lesions were found in 21 limbs (58.3%) while occlu-sive lesions were observed in 9 limbs (25%) and combined stenotic and occlusive lesions were found in 6 limbs (16.7%). The mean length of the treated lesions within the tibial arteries using DEB was 7.6±3.4m. Primary patency rate at 3, 6 and 12 months was 91.3%, 82.6% and 70.9%. While limb salvage rate at 3, 6 and 12 months was 91.6%, 81.8% and 72.8% respectively.Conclusion: With the rapid advancement in the endovas-cular tools & equipment, the early results is encouraging and promising with additional application of DEB for patients with infra-popliteal arterial disease in comparison to the traditional use of plain uncoated balloons. However, the mid-term and late results of the IN.PACT DEEP study suggest that an extreme caution is to be considered in this field.

Analysis of Interventionalists' Natural Behaviors for Recognizing Motion Patterns of Endovascular Tools During Percutaneous Coronary Interventions.

Many robotic platforms can indeed reduce radiation exposure to clinicians during percutaneous coronary intervention (PCI), however, interventionalists' natural manipulations are rarely involved in robot-assisted PCI. This requires more attention to analyze interventionalists' natural behaviors during conventional PCI. In this study, four types of natural behavior (i.e., muscle activity, hand motion, proximal force, and finger motion) were synchronously acquired from ten subjects while performing six typical types of guidewire manipulation. These behaviors are evaluated by a hidden Markov model (HMM) based analysis framework for relevant behavior selection. Relevant behaviors are further used as the input of two HMM-based classification frameworks to recognize guidewire motion patterns. Experimental results show that under the basic classification framework (BCF), 91.01% and 93.32% recognition accuracies can be achieved by using all behaviors and relevant behaviors, respectively. Furthermore, the hierarchical classification framework can significantly enhance the recognition ability of relevant behaviors with an accuracy of 96.39%. These promising results demonstrate great potential of proposed methods for promoting the future design of human-robot interfaces in robot-assisted PCI.

Introduction: Endovascular Neurosurgery.

Remarkable developments in the field of endovascular neurosurgery have been witnessed in the last decade. The success of endovascular therapy for ischemic stroke treatment is now irrefutable, making it an accepted standard of care. Endovascular treatment of cerebral aneurysms is no longer limited to primary coiling but now includes options such as stent or balloon assistance and flow diversion and applications utilizing neck reconstruction, intrasaccular, and bifurcation-specific devices. Balloons, liquid embolic agents, and flow-directed catheters have revolutionized the treatment of arteriovenous malformations and fistulae. The ongoing development of endovascular tools has led to novel and expanding approaches (for example, transvenous arteriovenous malformation embolization and transradial access). With improved technology, transposterior communicating artery access and other endovascular strategies are being applied successfully across the anterior and posterior circulations and to lesions once deemed only surgically approachable. Yet, we would be remiss to attribute the successes of endovascular strategies only to the development of their tools. Improvements in both noninvasive and angiographic imaging (such as three-dimensional road map guidance) have provided a greater understanding of pathologic entities and allowed the pursuit of endovascular cures.In this issue of Neurosurgical Focus, we present a wide range of endovascular strategies for a variety of neurovascular pathologies. We hope this video supplement will not only demonstrate the applicability of tried-and-true endovascular strategies to difficult clinical situations but also highlight new and developing endovascular technologies. We thank the authors for their outstanding contributions.

Endovascular invasions for femoral-popliteal segment disorders of C andD-type according to TASC-II classification

Currently, direct re-vascularization for the management of critical limb ischemia (CLI) is effectuated through open and hybrid surgical treatments. At the same time, therapeutic recommendations for one of the methods appear as a subject of lasting discussions. Today TASC II (TransAtlantic Inter-Society Consensus for the Management of Peripheral Arterial Disease) adopted in 2007 is the most popular document that provides justifications for endovascular and surgical treatment of peripheral arterial disease. Clinical practice provides evidence that there is a significant number of patients having critical limb ischemia who suffer from vascular bed disorders and are classified as C or D-type according to TASC classification. Meanwhile, there also are cases when these patients have no other alternative than re-vascularization by means of open surgery, which is why endovascular invasion appears as the only method of re-vascularization for them. The article presents some results of comparative studies within endovascular and surgical tools aimed at revascularization in the area of femoral-popliteal segment, including cases where patients are classified as C and D-type. The results of shunting operations are compared to angioplasty and remote endarterectomy, whereas technical methods for re-entry during subintimal angioplasty are regarded apart. Despite the fact that there are medical recommendations for the use of endovascular and surgical methods depending on TASC II classification, today there is no evidence that these tools can be efficient in revascularization of femoral-popliteal segment. In order to identify the efficiency of distinct methods in revascularization of femoral-popliteal segment there a need in a number of extended randomized studies designed to evaluate the role of such factors, as anatomic location of the vascular bed disorder, the extent of a disease, the location of purolo-necrotic areas as well as other pathologies on the results of the study.

The use of video motion analysis to determine the impact of anatomic complexity on endovascular performance in carotid artery stenting

ObjectiveVideo motion analysis (VMA) uses fluoroscopic sequences to derive information on catheter and guidewire movement and is able to calculate two-dimensional catheter tip path length (PL) on the basis of frame-by-frame pixel coordinates. The objective of this study was to evaluate the effect of anatomic complexity on the efficiency of completion of defined stages of simulated carotid artery stenting as measured by VMA. MethodsTwenty interventionists each performed a standardized easy, medium, and difficult carotid artery stenting case in random order on an ANGIO Mentor (Simbionix, Airport City, Israel) simulator. Videos of all procedures were analyzed using VMA software, and performance was expressed in terms of two-dimensional guidewire tip trajectory distance (PL). Comparisons of PL were used to identify differences in cannulation performance of the participants between the three cases of varying difficulty. The procedure was subdivided into four procedural phases: arch navigation, common carotid artery (CCA) cannulation, external carotid manipulation, and carotid lesion crossing. Comparisons of PL were used to identify differences in performance between the three cases of varying difficulty for each of the procedural phases. ResultsThere were significant differences in PL in relation to anatomic complexity, with a stepwise increase in PL from easy to difficult cases: easy, median of 5000 pixels (interquartile range, 4075-5403 pixels); intermediate, 9059 (5974-14,553) pixels; difficult, 17,373 (11,495-26,594) pixels (P < .001). Similarly, during CCA cannulation, there was a stepwise increase in PL from easy to difficult cases: easy, 749 (603-1403) pixels; intermediate, 3274 (1544-8142) pixels; difficult, 8845 (5954-15,768) pixels (P < .001). There were no observed differences across the groups of anatomic difficulty for the phases of arch navigation, external carotid manipulation, and carotid lesion crossing. ConclusionsIncreasing anatomic complexity leads to significant increases in PL of endovascular tools, in particular during CCA cannulation. This increase in tool movement may have a bearing on clinical outcome.

In Reply to the Letter to the Editor Regarding “Operative Approaches for Lumbar Disc Herniation: A Systematic Review and Multiple Treatment Meta-Analysis of Conventional and Minimally Invasive Surgeries”

Thromboembolic complications remain a major reason for morbidity and mortality after flow diversion, in addition to hemorrhagic complications not limited to the brain predicated on the prolonged need for dual antiplatelet therapy. Surface modification to decrease thrombogenicity and accelerate aneurysm occlusion is a promising alteration to mitigate those risks. The Pipeline embolization device with Shield Technology possesses such characteristics; however, it has not yet been approved in the United States.We present the case of a 38-year-old woman with a Spetzler-Martin grade 4 left parietal arteriovenous malformation with a total of 8 feeding vessel aneurysms and recent rupture of 1 of those aneurysms that was treated with balloon-assisted coil embolization. Four M1-segment middle cerebral artery aneurysms and 1 supraclinoid internal carotid artery aneurysm were treated with 2 Pipeline embolization Shield devices after a compassionate use request was approved. At 3 weeks after the procedure, the patient experienced a minor ischemic stroke after having missed the prescribed dual antiplatelet therapy. At the 3-month follow-up examination, the patient was neurologically intact and all the aneurysms were occluded. Dual antiplatelet therapy was discontinued.Flow diverters with surface modification to decrease thrombogenicity and accelerate aneurysm occlusion are promising endovascular tools for patients at high risk of complications with dual antiplatelet therapy. The present case represents one of the first cases performed in the United States using such a device. Despite the favorable outcome in the present case, the question of whether such technology obviates the need for dual antiplatelet therapy remains to be determined.

Navigation and visualisation with HoloLens in endovascular aortic repair.

IntroductionEndovascular aortic repair (EVAR) is a minimal-invasive technique that prevents life-threatening rupture in patients with aortic pathologies by implantation of an endoluminal stent graft. During the endovascular procedure, device navigation is currently performed by fluoroscopy in combination with digital subtraction angiography. This study presents the current iterative process of biomedical engineering within the disruptive interdisciplinary project Nav EVAR, which includes advanced navigation, image techniques and augmented reality with the aim of reducing side effects (namely radiation exposure and contrast agent administration) and optimising visualisation during EVAR procedures. This article describes the current prototype developed in this project and the experiments conducted to evaluate it.MethodsThe current approach of the Nav EVAR project is guiding EVAR interventions in real-time with an electromagnetic tracking system after attaching a sensor on the catheter tip and displaying this information on Microsoft HoloLens glasses. This augmented reality technology enables the visualisation of virtual objects superimposed on the real environment. These virtual objects include three-dimensional (3D) objects (namely 3D models of the skin and vascular structures) and two-dimensional (2D) objects [namely orthogonal views of computed tomography (CT) angiograms, 2D images of 3D vascular models, and 2D images of a new virtual angioscopy whose appearance of the vessel wall follows that shown in ex vivo and in vivo angioscopies]. Specific external markers were designed to be used as landmarks in the registration process to map the tracking data and radiological data into a common space. In addition, the use of real-time 3D ultrasound (US) is also under evaluation in the Nav EVAR project for guiding endovascular tools and updating navigation with intraoperative imaging. US volumes are streamed from the US system to HoloLens and visualised at a certain distance from the probe by tracking augmented reality markers. A human model torso that includes a 3D printed patient-specific aortic model was built to provide a realistic test environment for evaluation of technical components in the Nav EVAR project. The solutions presented in this study were tested by using an US training model and the aortic-aneurysm phantom.ResultsDuring the navigation of the catheter tip in the US training model, the 3D models of the phantom surface and vessels were visualised on HoloLens. In addition, a virtual angioscopy was also built from a CT scan of the aortic-aneurysm phantom. The external markers designed for this study were visible in the CT scan and the electromagnetically tracked pointer fitted in each marker hole. US volumes of the US training model were sent from the US system to HoloLens in order to display them, showing a latency of 259±86 ms (mean±standard deviation).ConclusionThe Nav EVAR project tackles the problem of radiation exposure and contrast agent administration during EVAR interventions by using a multidisciplinary approach to guide the endovascular tools. Its current state presents several limitations such as the rigid alignment between preoperative data and the simulated patient. Nevertheless, the techniques shown in this study in combination with fibre Bragg gratings and optical coherence tomography are a promising approach to overcome the problems of EVAR interventions.