The role of robotic endovascular catheters in fenestrated stent grafting

The Role and Future of Artificial Intelligence in Robotic Image-Guided Interventions

Artificial intelligence and robotics are transforming interventional radiology, driven by advancements in computer vision, robotics and procedural automation. Historically focused on diagnostics, AI now also enhances procedural capabilities in IR, enabling future robotic systems to handle complex tasks such as catheter manipulation or needle placement with increasing precision and reliability. Early robotic systems in IR demonstrated improved accuracy in both vascular and percutaneous interventions, though none were equipped with automatic decision-making. This review tends to show the potential in improving procedural outcomes with AI for robotics, though challenges remain. Techniques like reinforcement learning and haptic vision are under investigation to address several issues, training robots to adapt based on real-time feedback from the environment. As AI-driven robotics evolve, IR could shift towards a model where human expertise oversees the technology rather than performs the intervention itself.

Autonomous navigation of catheters and guidewires in mechanical thrombectomy using inverse reinforcement learning

PURPOSE

Autonomous navigation of catheters and guidewires can enhance endovascular surgery safety and efficacy, reducing procedure times and operator radiation exposure. Integrating tele-operated robotics could widen access to time-sensitive emergency procedures like mechanical thrombectomy (MT). Reinforcement learning (RL) shows potential in endovascular navigation, yet its application encounters challenges without a reward signal. This study explores the viability of autonomous guidewire navigation in MT vasculature using inverse reinforcement learning (IRL) to leverage expert demonstrations.

METHODS

Employing the Simulation Open Framework Architecture (SOFA), this study established a simulation-based training and evaluation environment for MT navigation. We used IRL to infer reward functions from expert behaviour when navigating a guidewire and catheter. We utilized the soft actor-critic algorithm to train models with various reward functions and compared their performance in silico.

RESULTS

We demonstrated feasibility of navigation using IRL. When evaluating single- versus dual-device (i.e. guidewire versus catheter and guidewire) tracking, both methods achieved high success rates of 95% and 96%, respectively. Dual tracking, however, utilized both devices mimicking an expert. A success rate of 100% and procedure time of 22.6 s were obtained when training with a reward function obtained through 'reward shaping'. This outperformed a dense reward function (96%, 24.9 s) and an IRL-derived reward function (48%, 59.2 s).

CONCLUSIONS

We have contributed to the advancement of autonomous endovascular intervention navigation, particularly MT, by effectively employing IRL based on demonstrator expertise. The results underscore the potential of using reward shaping to efficiently train models, offering a promising avenue for enhancing the accessibility and precision of MT procedures. We envisage that future research can extend our methodology to diverse anatomical structures to enhance generalizability.

Learning Skill Characteristics From Manipulations

Percutaneous coronary intervention (PCI) has increasingly become the main treatment for coronary artery disease. The procedure requires high experienced skills and dexterous manipulations. However, there are few techniques to model PCI skill so far. In this study, a learning framework with local and ensemble learning is proposed to learn skill characteristics of different skill-level subjects from their PCI manipulations. Ten interventional cardiologists (four experts and six novices) were recruited to deliver a medical guidewire to two target arteries on a porcine model for in vivo studies. Simultaneously, translation and twist manipulations of thumb, forefinger, and wrist are acquired with electromagnetic (EM) and fiber-optic bend (FOB) sensors, respectively. These behavior data are then processed with wavelet packet decomposition (WPD) under 1-10 levels for feature extraction. The feature vectors are further fed into three candidate individual classifiers in the local learning layer. Furthermore, the local learning results from different manipulation behaviors are fused in the ensemble learning layer with three rule-based ensemble learning algorithms. In subject-dependent skill characteristics learning, the ensemble learning can achieve 100% accuracy, significantly outperforming the best local result (90%). Furthermore, ensemble learning can also maintain 73% accuracy in subject-independent schemes. These promising results demonstrate the great potential of the proposed method to facilitate skill learning in surgical robotics and skill assessment in clinical practice.

Overcoming Barriers and Advancements in Endovascular Robotics: A Review of Systems and Developments

Endovascular robots have the potential to revolutionize the field of vascular interventions by enhancing procedural efficiency, accuracy, and standardization. They aim to reduce radiation exposure, as well as physical strain on operators and medical staff, while enabling precise navigation of catheters through challenging anatomical structures. However, the widespread adoption of these robots faces barriers, such as real estate constraints, setup time, limited range of compatible tools, and high costs. This paper discusses these barriers and highlights Hansen Medical's Magellan and the Liberty robotic systems as notable examples. New developments will offer cost-effective, intuitive, and disposable approaches to endovascular procedures. Despite challenges, endovascular robots hold promise for improving access to endovascular therapy and transforming patient care in various healthcare settings.

Artificial intelligence in the autonomous navigation of endovascular interventions: a systematic review

Background

Autonomous navigation of catheters and guidewires in endovascular interventional surgery can decrease operation times, improve decision-making during surgery, and reduce operator radiation exposure while increasing access to treatment.

Objective

To determine from recent literature, through a systematic review, the impact, challenges, and opportunities artificial intelligence (AI) has for the autonomous navigation of catheters and guidewires for endovascular interventions.

Methods

PubMed and IEEEXplore databases were searched to identify reports of AI applied to autonomous navigation methods in endovascular interventional surgery. Eligibility criteria included studies investigating the use of AI in enabling the autonomous navigation of catheters/guidewires in endovascular interventions. Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA), articles were assessed using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). PROSPERO: CRD42023392259.

Results

Four hundred and sixty-two studies fulfilled the search criteria, of which 14 studies were included for analysis. Reinforcement learning (RL) (9/14, 64%) and learning from expert demonstration (7/14, 50%) were used as data-driven models for autonomous navigation. These studies evaluated models on physical phantoms (10/14, 71%) and in-silico (4/14, 29%) models. Experiments within or around the blood vessels of the heart were reported by the majority of studies (10/14, 71%), while non-anatomical vessel platforms "idealized" for simple navigation were used in three studies (3/14, 21%), and the porcine liver venous system in one study. We observed that risk of bias and poor generalizability were present across studies. No procedures were performed on patients in any of the studies reviewed. Moreover, all studies were limited due to the lack of patient selection criteria, reference standards, and reproducibility, which resulted in a low level of evidence for clinical translation.

Conclusion

Despite the potential benefits of AI applied to autonomous navigation of endovascular interventions, the field is in an experimental proof-of-concept stage, with a technology readiness level of 3. We highlight that reference standards with well-identified performance metrics are crucial to allow for comparisons of data-driven algorithms proposed in the years to come.

Systematic review registration

identifier: CRD42023392259.

New paradigms in minimally-invasive vascular surgery

INTRODUCTION

Vascular surgery has been greatly evolved during the last decades and novel minimally invasive techniques have been introduced. Aim of this review is to briefly present all these advances and compare them with traditional repairs.

AREAS COVERED

The authors have extensively searched literature through the Pubmed and Embase databases. All articles published up to December 2021 referring to minimally invasive techniques used for treatment of peripheral artery disease, carotid disease, aortic aneurysms and venous disease were evaluated. Minimally invasive techniques under investigation included endovascular and hybrid techniques, robot-assisted and laparoscopic approaches.

EXPERT OPINION

Several minimally invasive techniques such as endovascular and hybrid approaches have been extensively used during the last two decades to treat vascular surgery patients offering them lower mortality and morbidity risks. Novel robot assisted techniques have shown promising results in preclinical studies although further clinical evaluation is needed.

Robot-assisted techniques in vascular and endovascular surgery

For thousands of years, robots have inspired the imagination of humans, but it was only about 35 years ago that a robot was used for the first time in medicine. Since then, robot-assisted procedures have become increasingly popular in urology, general surgical specialties, and gynecology. Robot-assisted vascular surgery was first introduced in 2002 and was thought to overcome the limitations of laparoscopy. However, it did not gain widespread popularity, and its usage is still limited to a few centers worldwide. Robot-assisted endovascular procedures, on the other hand, while still in its infancy, have become a promising alternative to existing techniques. The improvements of the robotic systems promote better surgical performance and reduce occupational hazards for vascular and endovascular surgeons. A comprehensive review of literature was performed using the search terms “robotic,” “robot assisted,” “vascular surgery,” and “aortic” for surgical procedures or “robotic,” “robot assisted,” and “endovascular” for endovascular procedures. Full text articles that were published between January 1990 and March 2021 were included. This review summarizes the development of the techniques for robot-assisted vascular and endovascular surgery in recent years, its outcomes, advantages, disadvantages, and perspectives.

Robotic endovascular surgery: current and future practice

Minimally invasive techniques have been at the forefront of surgical progress, and the evolution of endovascular robotic technologies has seen a paradigm shift in the focus of future innovation. Endovascular robotic technology may help overcome many of the challenges associated with traditional endovascular techniques by enabling greater control, stability, and precision of target navigation and treatment, while simultaneously reducing operator learning curves and improving safety. Several robotic systems have been developed to perform a broad range of endovascular procedures, but none have been used at scale or widely in routine practice, and the evidence for their safety, effectiveness, and efficiency remains limited. High cost and device complexity, lack of haptic feedback, and limited integration and interoperability with existing equipment and devices are the principal technology, cost, and sustainability barriers to the scalability and widespread adoption in day-to-day practice. In order to fully realize its potential, future robotic innovation must ensure compatibility with a range of off-the-shelf equipment that can be tracked and exchanged quickly during a procedure and come together with developments in navigation, tracking, and imaging. Reducing cost and complexity and supporting sustainability of the technology is key. In parallel, new technologies must be evaluated by clear and transparent standardized outcomes and be accompanied by robust clinical training. Key to the successful future development and dissemination of robotic technology is open collaboration among industry, clinicians, and patients in order to fully understand and address current challenges and enable the technology to realize its full potential.

Comparison of manual versus robot-assisted contralateral gate cannulation in patients undergoing endovascular aneurysm repair

PURPOSE

Robotic endovascular technology may offer advantages over conventional manual catheter techniques. Our aim was to compare the endovascular catheter path-length (PL) for robotic versus manual contralateral gate cannulation during endovascular aneurysm repair (EVAR), using video motion analysis (VMA).

METHODS

This was a multicentre retrospective cohort study with fluoroscopic video recordings of 24 EVAR cases (14 robotic, 10 manual) performed by experienced operators (> 50 procedures), obtained from four leading European centres. Groups were comparable with no statistically significant differences in aneurysm size (p = 0.47) or vessel tortuosity (p = 0.68). Two trained assessors used VMA to calculate the catheter PL during contralateral gate cannulation for robotic versus manual approaches.

RESULTS

There was a high degree of inter-observer reliability (Cronbach's α > 0.99) for VMA. Median robotic PL was 35.7 cm [interquartile range, IQR (30.8-51.0)] versus 74.1 cm [IQR (44.3-170.4)] for manual cannulation, p = 0.019. Robotic cases had a median cannulation time of 5.33 min [IQR (4.58-6.49)] versus 1.24 min [IQR (1.13-1.35)] in manual cases (p = 0.0083). Generated efficiency ratios (PL/aorto-iliac centrelines) was 1.6 (1.2-2.1) in robotic cases versus 2.6 (1.7-7.0) in manual, p = 0.031.

CONCLUSION

Robot-assisted contralateral gate cannulation in EVAR leads to decreased navigation path lengths and increased economy of movement compared with manual catheter techniques. The benefit could be maximised by prioritising robotic catheter shaping over habituated reliance on guidewire manipulation. Robotic technology has the potential to reduce the endovascular footprint during manipulations even for experienced operators with the added advantage of zero radiation exposure.

Qualitative and Quantitative Assessment of Technical Skills in Percutaneous Coronary Intervention: In Vivo Porcine Studies

OBJECTIVE

Technical skill assessment plays an important role in the professional development of an interventionalist in percutaneous coronary intervention (PCI). However, most of the traditional assessment methods are time consuming and subjective. This paper aims to develop objective assessment techniques.

METHODS

In this study, a natural-behavior-based assessment framework is proposed to qualitatively and quantitatively assess technical skills in PCI. In vivo porcine studies were conducted to deliver a medical guidewire to two target coronaries of left circumflex arteries by six novice and four expert interventionalists. Simultaneously, four types of natural behaviors (i.e., hand motion, proximal force, muscle activity, and finger motion) were acquired from the subjects' dominant hand and arm. The features extracted from the behaviors of different skill-level groups were compared using the Mann-Whitney U-test for effective behavior selection. The effective ones were further applied in the Gaussian-mixture-model-based qualitative assessment and Mahalanobis-distance-based quantitative assessment.

RESULTS

The qualitative assessment achieves an accuracy of 92% to distinguish the novice and expert attempts, which is significantly higher than that of using single guidewire motions. Furthermore, the quantitative assessment can assign objective and effective scores for all attempts, indicating high correlation ( R = 0.9225) to those obtained by traditional methods.

CONCLUSION

The objective, effective, and comprehensive assessment of technical skills can be provided by qualitatively and quantitatively analyzing interventionalists' natural behaviors in PCI.

SIGNIFICANCE

This paper suggests a novel approach for the technical skill assessment and the promising results demonstrate the great importance and effectiveness of the proposed method for promoting the development of objective assessment techniques.

Endovascular robotics

The current state and the future direction.

Design and Experimental Validation of an Active Catheter for Endovascular Navigation

Endovascular techniques have many advantages but rely strongly on operator skills and experience. Robotically steerable catheters have been developed but few are clinically available. We describe here the development of an active and efficient catheter based on shape memory alloys (SMA) actuators. We first established the specifications of our device considering anatomical constraints. We then present a new method for building active SMA-based catheters. The proposed method relies on the use of a core body made of three parallel metallic beams and integrates wire-shaped SMA actuators. The complete device is encapsulated into a standard 6F catheter for safety purposes. A trial-and-error campaign comparing 70 different prototypes was conducted to determine the best dimensions of the core structure and of the SMA actuators with respect to the imposed specifications. The final prototype was tested on a silicon-based arterial model and on a 23 kg pig. During these experiments, we were able to cannulate the supra-aortic trunks and the renal arteries with different angulations and without any complication. A second major contribution of this paper is the derivation of a reliable mathematical model for predicting the bending angle of our active catheters. We first use this model to state some general qualitative rules useful for an iterative dimensional optimization. We then perform a quantitative comparison between the actual and the predicted bending angles for a set of 13 different prototypes. The relative error is less than 20% for bending angles between 100 deg and 150 deg, which is the interval of interest for our applications.

CathROB: A Highly Compact and Versatile Remote Catheter Navigation System

Several remote catheter navigation systems have been developed and are now commercially available. However, these systems typically require specialized catheters or equipment, as well as time-consuming operations for the system set-up. In this paper, we present CathROB, a highly compact and versatile robotic system for remote navigation of standard tip-steerable electrophysiology (EP) catheters. Key features of CathROB include an extremely compact design that minimizes encumbrance and time for system set-up in a standard cath lab, a force-sensing mechanism, an intuitive command interface, and functions for automatic catheter navigation and repositioning. We report in vitro and in vivo animal evaluation of CathROB. In vitro results showed good accuracy in remote catheter navigation and automatic repositioning (1.5 ± 0.6 mm for the left-side targets, 1.7 ± 0.4 mm for the right-side targets). Adequate tissue contact was achieved with remote navigation in vivo. There were no adverse events, including absence of cardiac perforation or cardiac damage, indicative of the safety profile of CathROB. Although further preclinical and clinical studies are required, the presented CathROB system seems to be a promising solution for an affordable and easy-to-use remote catheter navigation.

Robotic system-assisted endovascular treatment of a dissection-related pseudoaneurysm of the celiac axis secondary to fibromuscular dysplasia

Spontaneous celiac artery dissection caused by fibromuscular dysplasia is rare. Subsequent thrombosis and occlusion of the celiac trunk can result in intestinal ischemia and hepatic failure. We describe a case of spontaneous celiac artery dissection with an associated pseudoaneurysm caused by fibromuscular dysplasia, extending into the common hepatic artery. An endovascular intervention featuring robotic-assisted celiac artery cannulation with stent-assisted coil embolization resulted in successful treatment.

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

PURPOSE

Transcatheter 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.

METHODS

A silicon phantom model of a type I aortic arch was used for this study. Twelve endovascular surgeons, divided into two experience groups, experts ([Formula: see text]) and novices ([Formula: see text]), performed cannulation of the aorta, representative of valve placement in TAVI. Each participant completed two TAVI experiments, one with conventional catheters and one with the Magellan robotic platform. Video sequences of the fluoroscopic monitor were recorded for procedural processing. A semi-automated tracking software provided the 2D coordinates of the catheter/guidewire tip. In addition, the aorta phantom was segmented in the videos and the shape of the entire catheter was manually annotated in a subset of the available video frames using crowdsourcing. The TAVI procedure was divided into two stages, and various metrics, representative of the catheter's overall navigation as well as its relative movement to the vessel wall, were developed.

RESULTS

Experts consistently exhibited lower values of procedure time and dimensionless jerk, and higher average speed and acceleration than novices. Robotic navigation resulted in increased average distance to the vessel wall in both groups, a surrogate measure of safety and reduced risk of embolisation. Discrimination of experience level and types of equipment was achieved with the generated motion features and established clustering algorithms.

CONCLUSIONS

Evaluation of surgical skills is possible through the analysis of the catheter/guidewire motion pattern. The use of robotic endovascular platforms seems to enable more precise and controlled catheter navigation.

Motion-adapted catheter navigation with real-time instantiation and improved visualisation

The improvements to catheter manipulation by the use of robot-assisted catheter navigation for endovascular procedures include increased precision, stability of motion and operator comfort. However, navigation through the vasculature under fluoroscopic guidance is still challenging, mostly due to physiological motion and when tortuous vessels are involved. In this paper, we propose a motion-adaptive catheter navigation scheme based on shape modelling to compensate for these dynamic effects, permitting predictive and dynamic navigations. This allows for timed manipulations synchronised with the vascular motion. The technical contribution of the paper includes the following two aspects. Firstly, a dynamic shape modelling and real-time instantiation scheme based on sparse data obtained intra-operatively is proposed for improved visualisation of the 3D vasculature during endovascular intervention. Secondly, a reconstructed frontal view from the catheter tip using the derived dynamic model is used as an interventional aid to user guidance. To demonstrate the practical value of the proposed framework, a simulated aortic branch cannulation procedure is used with detailed user validation to demonstrate the improvement in navigation quality and efficiency.

Next-generation robotic surgery--from the aspect of surgical robots developed by industry

At present, much of the research conducted worldwide focuses on extending the ability of surgical robots. One approach is to extend robotic dexterity. For instance, accessibility and dexterity of the surgical instruments remains the largest issue for reduced port surgery such as single port surgery or natural orifice surgery. To solve this problem, a great deal of research is currently conducted in the field of robotics. Enhancing the surgeon's perception is an approach that uses advanced sensor technology. The real-time data acquired through the robotic system combined with the data stored in the robot (such as the robot's location) provide a major advantage. This paper aims at introducing state-of-the-art products and pre-market products in this technological advancement, namely the robotic challenge in extending dexterity and hopefully providing the path to robotic surgery in the near future.

Feasibility and Safety of Renal and Visceral Target Vessel Cannulation Using Robotically Steerable Catheters During Complex Endovascular Aortic Procedures

Purpose: To evaluate the safety and success of target vessel cannulation in the visceral aortic segment using the Magellan robotic catheter system (RCS) during complex endovascular aortic procedures. Methods: Robotic navigation was attempted for access to 37 target vessels in 15 patients (14 men; mean age 75±10 years) during 16 fenestrated and/or branched stent-grafting procedures and 1 endovascular repair requiring the chimney technique. For each target vessel, robotic navigation was attempted for a maximum of 15 minutes; if cannulation was unsuccessful in that time, manual catheters were employed. Safety was evaluated by recording intraoperative adverse events, intraoperative complications related to robotic navigation, and postoperative complications. Technical success of robotic cannulation, wire cannulation times, and times for inserting the leader over the wire in the target vessels were recorded to assess RCS performance. Results: Successful robotic cannulation was achieved for 30 (81%) of the 37 target vessels, with a median wire cannulation time of 263 seconds (range 40–780) and a median 15 seconds (range 5–450) for inserting the leader over the wire. No intraoperative complications related to robotic navigation were observed. Seven of 27 arteries accessed via 7 fenestrations could not be cannulated within 15 minute s; all were cannulated successfully using conventional catheters (mean cannulation time 31±7 minutes). All 10 target vessels accessed via branches and chimney stents were successfully cannulated with the RCS. Conclusion: Cannulation of target vessels with the RCS during complex endovascular aortic procedures is feasible and safe. The robotic system was particularly effective for branched and chimney stents.

Robotics and surgery: A sustainable relationship?

Robotic surgery is increasingly being employed to overcome the disadvantages associated with use of conventional techniques such as laparoscopy. However, despite significant promise, there are some clear disadvantages and robust evidence base supporting the use of robotic assistance remains lacking. In this paper, the advantages and drivers for robotics will be discussed, its drawbacks and its future role in surgery.

Current state in tracking and robotic navigation systems for application in endovascular aortic aneurysm repair

OBJECTIVE

This study reviewed the current developments in manual tracking and robotic navigation technologies for application in endovascular aortic aneurysm repair (EVAR).

METHODS

EMBASE and MEDLINE databases were searched for studies reporting manual tracking or robotic navigation systems that are able to manipulate endovascular surgical tools during abdominal or thoracic aortic aneurysm repair. Reports were grouped by the navigation systems and categorized into phantom, animal, and clinical studies. First, the general characteristics of each system were compared. Second, target registration error and deployment error were used to compare the accuracy of the tracking systems. Third, all systems were reviewed for fluoroscopy time (FT), radiation dose, and contrast volumes, if reported, in rigid and nonrigid studies. Fourth, vascular cannulation performance of the systems was compared, studying cannulation time, Imperial College Complex Cannulation Scoring Tool score, and the number of wall hits and catheter movements within rigid studies.

RESULTS

Of 721 articles and references found, 18 studies of four different navigation systems were included: the Aurora (Northern Digital, Waterloo, Ontario, Canada) tracking system, the StealthStation (Medtronic Inc, Minneapolis, Minn) tracking system, an ultrasound localization tracking system, and the Sensei (Hansen Medical, Mountain View, Calif) steerable remote-controlled robotic navigation system. The mean tracking accuracy averaged 1 mm for the three manual tracking systems measured in a rigid environment. An increase of target registration error reaching >3 mm was reported when measured in a nonrigid experimental environment or due to external distortion factors. Except within small-animal studies or case studies, no evidence was found on reduction of clinical outcome parameters, such as FT, radiation dose, and contrast volumes, within clinical EVAR. A comparison of vascular cannulation performance in rigid studies revealed that the Sensei robotic system might have an advantage during advanced cannulation compared with standard cannulation within complex cannulations tasks.

CONCLUSIONS

This review summarizes the current studies on manual tracking and robotic navigation systems for application in EVAR. The main focus of these systems is improving aortic vessel cannulation, required in complex EVAR, in which the robotic system with the improved steerability is favored over manual tracking systems or conventional cannulation. All reviewed tracking systems still require X-ray for anatomic imaging, stent graft deployment, and device registration. Although the current reviewed endovascular navigation systems have shown their potential in phantom and animal studies, clinical trials are too limited to conclude that these systems can improve EVAR outcomes or that they can systematically reduce FTs, radiation doses, and contrast volumes during (complex) EVAR.

Impact of intraoperative adverse events during branched and fenestrated aortic stent grafting on postoperative outcome

Objective

Fenestrated and branched endovascular devices are increasingly used for complex aortic diseases, and despite the challenging nature of these procedures, early experiences from pioneering centers have been encouraging. The objectives of this retrospective study were to report our experience of intraoperative adverse events (IOAEs) during fenestrated and branched stent grafting and to analyze the impact on clinical outcomes.

Methods

Consecutive patients treated with fenestrated and branched stent grafting in a tertiary vascular center between February 2006 and October 2013 were evaluated. A prospectively maintained computerized database was scrutinized and updated retrospectively. Intraoperative angiograms were reviewed to identify IOAEs, and adverse events were categorized into three types: target vessel cannulation, positioning of graft components, and intraoperative access. Clinical consequences of IOAEs were analyzed to ascertain whether they were responsible for death or moderate to severe postoperative complications.

Results

During the study period, 113 consecutive elective patients underwent fenestrated or branched stent grafting. Indications for treatment were asymptomatic complex abdominal aortic aneurysms (CAAAs, n = 89) and thoracoabdominal aortic aneurysms (TAAAs, n = 24). Stent grafts included fenestrated (n = 79) and branched (n = 17) Cook stent grafts (Cook Medical, Bloomington, Ind), Ventana (Endologix, Irvine, Calif) stent grafts (n = 9), and fenestrated Anaconda (Vascutek Terumo, Scotland, UK) stent grafts (n = 8). In-hospital mortality rates for the CAAA and TAAA groups were 6.7% (6 of 89) and 12.5% (3 of 24), respectively. Twenty-eight moderate to severe complications occurred in 21 patients (18.6%). Spinal cord ischemia was recorded in six patients, three of which resolved completely. A total of 37 IOAEs were recorded in 34 (30.1%) patients (22 CAAAs and 12 TAAAs). Of 37 IOAEs, 15 (40.5%) resulted in no clinical consequence in 15 patients; 17 (45.9%) were responsible for moderate to severe complications in 16 patients, and five (13.5%) led to death in four patients. The composite end point death/nonfatal moderate to severe complication occurred more frequently in patients with IOAEs compared with patients without IOAEs (20 of 34 vs 12 of 79; P < .0001).

Conclusions

In this contemporary series, IOAEs were relatively frequent during branched or fenestrated stenting procedures and were often responsible for significant complications.

Robotic endovascular surgery

The purpose of this review is to compare conventional endovascular procedures and the robotic endovascular approach in aortic aneurysm repair. Despite advantages over open surgery, conventional endovascular surgery has limitations. To develop an alternative, efforts have been focused on robotic endovascular systems. Two of the 3 studies comparing procedure times demonstrated reduced procedure time in the robotic group, by 6 times ( p < 0.05). One study demonstrated that robotic procedures reduced fluoroscopic exposure time by 12 minute ( p < 0.001). Three in-vitro studies showed that the number of movements required in robotic surgery was reduced up to 10 times ( p < 0.05). One of 2 studies measuring robotic performance score showed a better performance score in the robotic endovascular group ( p = 0.007). These results demonstrate that the robotic technique has multiple advantages over the conventional procedure, including improved catheter stability, a shorter learning curve, reduced procedure time, and better performance in cannulating tortuous vessels. However, robotic endovascular technology may be limited by the cost of the system, the size of the catheter, and the setup time required preoperatively. Further comparative studies between conventional and robotic approaches regarding cost-effectiveness, safety, and performance in cases involving complex anatomy and fenestrated stent grafts are essential. Nevertheless, this revolutionary technology is increasingly popular and may be the next milestone in endovascular surgery.

Improved catheter navigation with 3D electromagnetic guidance

PURPOSE

To evaluate the in vitro performance of an electromagnetic navigation system (ENS) in aortic arch branch cannulation and describe its role for fenestrated endograft deployment.

METHODS

Reconstructed multidetector computed tomography images of silicone phantoms representing the aortic arch and a thoracoabdominal aortic aneurysm were uploaded onto the StealthStation workstation, which provided 3-dimensional visualization of a guidewire by tracking sensors on its tip. For the evaluation of aortic arch branch cannulation, 9 operators were asked to cannulate the phantom's common carotid and left subclavian arteries using the (1) ENS, (2) a 2-dimensional (2D) screen setting simulating fluoroscopy, and (3) both imaging modalities. Analysis included procedure times, number of wall hits, and the Imperial College Complex Cannulation Scoring Tool (IC3ST) qualitative performance score. To evaluate the ability of the ENS during positioning of a fenestrated stent-graft over the visceral segment, a custom-made 4-vessel fenestrated stent-graft with sensors on the fenestrations was deployed 5 consecutive times using the ENS as the exclusive imaging technique.

RESULTS

In the aortic arch model, cannulation times were significantly longer in the ENS group. However, compared with the 2D version, using both imaging modalities reduced fluoroscopic times [median 26.5 seconds (IQR 19.7-30.7) vs. 87 seconds (IQR 64-128), p<0.0001] and wall hits [median 8.5 (IQR 16-38) vs. 14 (IQR 11-160, p<0.05), while improving IC3ST performance scores [31/35 (IQR 30-31.2) vs. 25/35 (IQR 24-27), p<0.05]. Following deployment of the endograft with tracked fenestrations, the 4 visceral vessels were cannulated in all cases using only the ENS.

CONCLUSION

The use of the ENS as a complementary imaging modality might be beneficial in terms of radiation exposure, cannulation performance, and positioning of intravascular devices.

Strategies to tackle unrecognized bilateral renal artery occlusion after endovascular aneurysm repair

BACKGROUND

Unintentional renal artery occlusion after endovascular aortic aneurysm repair (EVAR) is an uncommon phenomenon. The sequelae from this specific complication are severe; consequently, the topic of renal artery coverage is a pertinent issue. We present a case series of patients undergoing EVAR with unintentional renal artery coverage, review the treatment options available, and suggest a treatment algorithm for this scenario based on the evidence.

METHODS AND RESULTS

We report four patients who were found to have renal artery occlusion after EVAR detected up to 5 weeks postoperatively. Renal revascularization was achieved using endovascular renal artery stenting in two patients, and open hepato-spleno-renal bypass in the remaining two cases. Treatment strategies used led to symptom resolution and recovery of renal function in all cases.

CONCLUSIONS

Both open and endovascular techniques may be used as procedures to treat this condition-the choice of procedure is primarily determined by accessibility of the renal orifice.

Emerging technologies for image guidance and device navigation in interventional radiology

Recent developments in image-guidance and device navigation, along with emerging robotic technologies, are rapidly transforming the landscape of interventional radiology (IR). Future state-of-the-art IR procedures may include real-time three-dimensional imaging that is capable of visualizing the target organ, interventional tools, and surrounding anatomy with high spatial and temporal resolution. Remote device actuation is becoming a reality with the introduction of novel magnetic-field enabled instruments and remote robotic steering systems. Robots offer several degrees of freedom and unprecedented accuracy, stability, and dexterity during device navigation, propulsion, and actuation. Optimization of tracking and navigation of interventional tools inside the human body will be critical in converting IR suites into the minimally invasive operating theaters of the future with increased safety and unsurpassed therapeutic efficacy. In the not too distant future, individual image guidance modalities and device tracking methods could merge into autonomous, multimodality, multiparametric platforms that offer real-time data of anatomy, morphology, function, and metabolism along with on-the-fly computational modeling and remote robotic actuation. The authors provide a concise overview of the latest developments in image guidance and device navigation, while critically envisioning what the future might hold for 2020 IR procedures.

Tortuous iliac systems--a significant burden to conventional cannulation in the visceral segment: is there a role for robotic catheter technology?

PURPOSE

To attempt to quantify the effect of varying degrees of iliac tortuosity on maneuverability and "torquability" of endovascular catheters in the visceral segment, comparing conventional and robotic cannulation techniques.

MATERIALS AND METHODS

In a fenestrated endograft within a pulsatile phantom, 10 experienced operators cannulated the renal arteries via three different access vessels of varying iliac tortuosity with the use of conventional and robotic techniques. All procedures were performed in the angiography suite and recorded for blinded video assessment for quantitative (time, catheter-tip movements) and qualitative metrics (operator performance scores).

RESULTS

In total, 120 cannulations were observed. With increasing iliac tortuosity, median time and number of catheter movements required for renal cannulation with conventional techniques increased in stepwise fashion for mild, moderate, and severe iliac tortuosity (times, 7.6 min [interquartile range (IQR), 4.6-9.3 min] vs 6.9 min [4.2-11.4 min] vs 17.7 min [13.3-22.6 min], respectively; movements, 184 [IQR, 110-351] vs 251 [207-395] vs 569 [409-616], respectively). Median renal cannulation times were significantly reduced with the use of the robotic system irrespective of mild, moderate, or severe tortuosity (times, 1.4 min [IQR, 1.1-1.9 min] vs 3 min [2.3-3.3 min] vs 2.8 min [1.5-3.9 min], respectively; movements, 19 [IQR, 14-27] vs 46 [43-58] vs 45 [40-66], respectively; P < .005). Overall operator performance scores improved significantly with the use of the robotic system irrespective of iliac tortuosity severity.

CONCLUSIONS

In cases of moderate to severe iliac tortuosity, conventional catheter manipulation and control becomes an issue. The improvement in positional control and predictability seen with advanced catheter designs may be amplified in cases of severe iliac tortuosity.

Three-dimensional electromagnetic navigation vs. fluoroscopy for endovascular aneurysm repair: a prospective feasibility study in patients

PURPOSE

To evaluate the in vivo feasibility of a 3-dimensional (3D) electromagnetic (EM) navigation system with electromagnetically-tracked catheters in endovascular aneurysm repair (EVAR).

METHODS

The pilot study included 17 patients undergoing EVAR with a bifurcated stent-graft. Ten patients were assigned to the control group, in which a standard EVAR procedure was used. The remaining 7 patients (intervention group) underwent an EVAR procedure during which a cone-beam computed tomography image was acquired after implantation of the main stent-graft. The 3D image was presented on the navigation screen. From the contralateral side, the tip of an electromagnetically-tracked catheter was visualized in the 3D image and positioned in front of the contralateral cuff in the main stent-graft. A guidewire was inserted through the catheter and blindly placed into the stent-graft. The placement of the guidewire was verified by fluoroscopy before the catheter was pushed over the guidewire. If the guidewire was incorrectly placed outside the stent-graft, the procedure was repeated. Successful placement of the guidewire had to be achieved within a 15-minute time limit.

RESULTS

Within 15 minutes, the guidewire was placed correctly inside the stent-graft in 6 of 7 patients in the intervention group and in 8 of 10 patients in the control group. In the intervention group, fewer attempts were needed to insert the guidewire correctly.

CONCLUSION

A 3D EM navigation system, used in conjunction with fluoroscopy and angiography, has the potential to provide more spatial information and reduce the use of radiation and contrast during endovascular interventions. This pilot study showed that 3D EM navigation is feasible in patients undergoing EVAR. However, a larger study must be performed to determine if 3D EM navigation is better than the existing practice for these patients.

Feasibility and safety of remote endovascular catheter navigation in a porcine model

PURPOSE

To evaluate the feasibility and safety of a redesigned remotely operated vascular catheter versus manual catheter manipulation in a porcine model.

METHODS

Following femoral artery puncture and wire insertion, 4 pigs had either a robotically steered catheter (3 animals) or standard manual catheter manipulation to cannulate the contralateral iliac artery, bilateral renal arteries, and the superior mesenteric artery. After harvesting, the vessels were evaluated histologically by an independent laboratory using hematoxylin and eosin staining. Each cannulated artery was assessed for disruption of the intimal surface, intimal thrombus, damage to the tunica muscularis (dissection), mural hemorrhage, and inflammation by a pathologist who was blinded to the technique utilized for cannulation.

RESULTS

No histological evidence of intimal thrombus, disruption, inflammation, or hemorrhage was demonstrated in any vessel section from the robotic cases. In the SMA, 1 of 61 sections from the robotic cases demonstrated mild focal dissection, while 1 of 9 slices from the manual control showed intimal thrombus. Of 129 slices from the renal arteries catheterized by the robotic system, 4 sections demonstrated mild focal dissection, while 2 of 23 sections from the manual control showed grade 1 intimal thrombus. In the iliofemoral arteries, 3 of 91 sections showed mild focal dissection in the robotic cases; in the manual control, 1 of 9 slices demonstrated extensive dissection and another showed mild intimal thrombus.

CONCLUSION

The robotically operated catheter was at least as safe as manual manipulation. More extensive injury was actually observed with the manual technique. This newly designed robotic catheter has the potential to offer many advantages in terms of flexibility and range of motion.

Evaluation of robotic endovascular catheters for arch vessel cannulation

OBJECTIVE

Conventional catheter instability and embolization risk limits the adoption of endovascular therapy in patients with challenging arch anatomy. This study investigated whether arch vessel cannulation can be enhanced by a remotely steerable robotic catheter system.

METHODS

Seventeen clinicians with varying endovascular experience cannulated all arch vessels within two computed tomography-reconstructed pulsatile flow phantoms (bovine type I and type III aortic arches), under fluoroscopic guidance, using conventional and robotic techniques. Quantitative (catheterization times, catheter tip movements, vessel wall hits, catheter deflection) and qualitative metrics (Imperial College Complex Endovascular Cannulation Scoring Tool [IC3ST]) performance scores were compared.

RESULTS

Robotic catheterization techniques resulted in a significant reduction in median carotid artery cannulation times and the median number of catheter tip movements for all vessels. Vessel wall contact with the aortic arch wall was reduced to a median of zero with robotic catheters. During stiff guidewire exchanges, robotic catheters maintained stability with zero deflection, independent of the distance the catheter was introduced into the carotid vessels. Overall IC3ST performance scores (interquartile range) were significantly improved using the robotic system: Type I arch score was 26/35 (20-30.8) vs 33/35 (31-34; P = .001), and type III arch score was 20.5/35 (16.5-28.5) vs 26.5/35 (23.5-28.8; P = .001). Low- and medium-volume interventionalists demonstrated an improvement in performance with robotic cannulation techniques. The high-volume intervention group did not show statistically significant improvement, but cannulation times, movements, and vessel wall hits were significantly reduced.

CONCLUSION

Robotic technology has the potential to reduce the time, risk of embolization and catheter dislodgement, radiation exposure, and the manual skill required for carotid and arch vessel cannulation, while improving overall performance scores.

Clinical applications of robotic technology in vascular and endovascular surgery

BACKGROUND

Emerging robotic technologies are increasingly being used by surgical disciplines to facilitate and improve performance of minimally invasive surgery. Robot-assisted intervention has recently been introduced into the field of vascular surgery to potentially enhance laparoscopic vascular and endovascular capabilities. The objective of this study was to review the current status of clinical robotic applications in vascular surgery.

METHODS

A systematic literature search was performed in order to identify all published clinical studies related to robotic implementation in vascular intervention. Web-based search engines were searched using the keywords "surgical robotics," "robotic surgery," "robotics," "computer assisted surgery," and "vascular surgery" or "endovascular" for articles published between January 1990 and November 2009. An evaluation and critical overview of these studies is reported. In addition, an analysis and discussion of supporting evidence for robotic computer-enhanced telemanipulation systems in relation to their applications in laparoscopic vascular and endovascular surgery was undertaken.

RESULTS

Seventeen articles reporting on clinical applications of robotics in laparoscopic vascular and endovascular surgery were detected. They were either case reports or retrospective patient series and prospective studies reporting laparoscopic vascular and endovascular treatments for patients using robotic technology. Minimal comparative clinical evidence to evaluate the advantages of robot-assisted vascular procedures was identified. Robot-assisted laparoscopic aortic procedures have been reported by several studies with satisfactory results. Furthermore, the use of robotic technology as a sole modality for abdominal aortic aneurysm repair and expansion of its applications to splenic and renal artery aneurysm reconstruction have been described. Robotically steerable endovascular catheter systems have potential advantages over conventional catheterization systems. Promising results from applications in cardiac interventions and preclinical studies have urged their use in vascular surgery. Although successful applications in endovascular repair of abdominal aortic aneurysm and lower extremity arterial disease have been reported, published clinical experience with the endovascular robot is limited.

CONCLUSIONS

Robotic technology may enhance vascular surgical techniques given preclinical evidence and early clinical reports. Further clinical studies are required to quantify its advantages over conventional treatments and define its role in vascular and endovascular surgery.

Advanced catheter technology: is this the answer to overcoming the long learning curve in complex endovascular procedures

INTRODUCTION

Advanced endovascular procedures require a high degree of skill with a long learning curve. We aimed to identify differential increases in endovascular skill acquisition in novices using conventional (CC), manually steerable (MSC) and robotic endovascular catheters (RC).

MATERIALS/METHODS

10 novices cannulated all vessels within a CT-reconstructed pulsatile-flow arch phantom in the Simulated Endovascular Suite. Subjects were randomly assigned to conventional/manually-steerable/robotic techniques as the first procedure undertaken. The operators repeated the task weekly for 5 weeks. Quantitative (cannulation times, wire/catheter-tip movements, vessel wall hits) and qualitative metrics (validated rating scale (IC3ST)) were compared.

RESULTS

Subjects exhibited statistically significant differences when comparing initial to final performance for total procedure times and catheter-tip movements with all catheter types. Sequential non-parametric comparisons identified learning curve plateau levels at weeks 2 or 3(RCs, MSCs), and at week 4(CCs) for the majority of metrics. There were significantly fewer catheter-tip movements using advanced catheter technology after training (Week 5: CC 74 IQR(59-89) versus MSC 62(44-81); p = 0.028, and RC 33 (28-44); p = 0.012). RCs virtually eliminated wall hits at the arch (CC 29(28-76) versus RC 8(6-9); p = 0.005) and produced significantly higher overall performance scores (p < 0.02).

CONCLUSION

Advanced endovascular catheters, although more intricate, do not seem to take longer to master and in some areas offer clear advantages with regards to positional control, at a faster rate. RCs seem to be the most intuitive and advanced skill acquisition occurs with minimal training. Robotic endovascular technology may have a significantly shorter path to proficiency allowing an increased number of trainees to attempt more complex endovascular procedures earlier and with a greater degree of safety.

Robot-assisted stenting of a high-grade anastomotic pulmonary artery stenosis following single lung transplantation

PURPOSE

To report robot-assisted stenting of a stenosis at the pulmonary artery anastomosis following lung transplantation, a rare complication that conveys poor prognosis even after surgical correction.

TECHNIQUE

The technique is illustrated in a 72-year-old man with end-stage lung disease who received a left single lung transplant. On postoperative day 54, he was evaluated for recurrent dyspnea on exertion that was due to a severe stenosis at the site of the pulmonary artery anastomosis. Balloon angioplasty was performed, and a 10-mm stent was deployed, with marked clinical improvement. Fourteen months later, he presented with recurrent symptoms due to in-stent restenosis. Multiple attempts at catheterization and balloon angioplasty of the stent failed. Due to the technical difficulty involved in maneuvering the balloon while maintaining stability, it was decided to repeat the angioplasty with the assistance of a Hansen Sensei remote robotic navigation system. The robotic arm markedly enhanced stability and facilitated successful navigation of the stented site. A 16-mm-diameter Wallstent was placed through the previously placed balloon-expandable stent and postdilated.

CONCLUSION

A remote robotic catheter navigation system was able to assist stenting of an anastomotic pulmonary artery stenosis following failure of conventional interventional techniques.

Hybrid and endovascular therapy for extensive thoracoabdominal aortic disease

The past 4 decades have witnessed tremendous strides in the evolution of endovascular technology with increased operator experience, greater availability of more sophisticated and versatile endovascular devices, and advances in imaging modalities. In an attempt to limit the physiologic derangements associated with aortic crossclamping and extensive tissue dissection during traditional open surgical repair of extensive thoracoabdominal aortic aneurysms, less invasive strategies have been explored using endovascular technology: hybrid approaches and solely endovascular techniques. This article describes these techniques and their advantages, their current role in thoracoabdominal aortic aneurysm repair and potential future developments in this field.