Despite the increasing popularity of endovascular intervention in clinical practice, there remains a lack of objective and quantitative metrics for skill evaluation of endovascular techniques. Data ...relating to the forces exerted during endovascular procedures and the behavioral patterns of endovascular clinicians is currently limited. This research proposes two platforms for measuring tool forces applied by operators and contact forces resulting from catheter–tissue interactions, as a means of providing accurate, objective metrics of operator skill within a realistic simulation environment. Operator manipulation patterns are compared across different experience levels performing various complex catheterization tasks, and different performance metrics relating to tool forces, catheter motion dynamics, and forces exerted on the vasculature are extracted. The results depict significant differences between the two experience groups in their force and motion patterns across different phases of the procedures, with support vector machine (SVM) classification showing cross-validation accuracies as high as 90% between the two skill levels. This is the first robust study, validated across a large pool of endovascular specialists, to present objective measures of endovascular skill based on exerted forces. The study also provides significant insights into the design of optimized metrics for improved training and performance assessment of catheterization tasks.
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.
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.
Objective Type B aortic dissection can be acutely complicated by rapid expansion, rupture, and malperfusion syndromes. Short-term adverse outcomes are associated with failure of the false lumen to ...thrombose. The reasons behind false lumen patency are poorly understood, and the objective of this pilot study was to use computational fluid dynamics reconstructions of aortic dissection cases to analyze the effect of aortic and primary tear morphology on flow characteristics and clinical outcomes in patients with acute type B dissections. Methods Three-dimensional patient-specific aortic dissection geometry was reconstructed from computed tomography scans of four patients presenting with acute type B aortic dissection and a further patient with sequential follow-up scans. The cases were selected based on their clinical presentation. Two were complicated by acute malperfusion that required emergency intervention. Three patients were uncomplicated and were managed conservatively. The patient-specific aortic models were used in computational simulations to assess the effect of aortic tear morphology on various parameters including flow, velocity, shear stress, and turbulence. Results Pulsatile flow simulation results showed that flow rate into the false lumen was dependent on both the size and position of the primary tear. Linear regression analysis demonstrated a significant relationship between percentage flow entering the false lumen and the size of the primary entry tear and an inverse relationship between false lumen flow and the site of the entry tear. Subjects complicated by malperfusion had larger-dimension entry tears than the uncomplicated cases (93% and 82% compared with 32% and 55%, respectively). Blood flow, wall shear stress, and turbulence levels varied significantly between subjects depending on aortic geometry. Highest wall shear stress (>7 Pa) was located at the tear edge, and progression of false lumen thrombosis was associated with prolonged particle residence times. Conclusions Results obtained from this preliminary work suggest that aortic morphology and primary entry tear size and position exert significant effects on flow and other hemodynamic parameters in the dissected aorta in this preliminary work. Blood flow into the false lumen increases with increasing tear size and proximal location. Morphologic analysis coupled with computational fluid dynamic modeling may be useful in predicting acute type B dissection behavior allowing for selection of proper treatment modalities, and further confirmatory studies are warranted.
Objective Conventional catheter manipulation in the arch and supra-aortic trunks carries a risk of cerebral embolization. This study proposes a platform for detailed quantitative analysis of contact ...forces (CF) exerted on the vasculature, in order to investigate the potential advantages of robotic navigation. Methods An anthropomorphic phantom representing a type I bovine arch was mounted and coupled onto a force/torque sensor. Three-axis force readings provided an average root-mean-square modulus, indicating the total forces exerted on the phantom. Each of the left subclavian, left common carotid, and right common carotid arteries was cannulated within a simulated endovascular suite with conventional (n = 42) vs robotic techniques (n = 30) by two operator groups: experts and novices. The procedure path was divided into three phases, and performance metrics corresponding to mean and maximum forces, force impact over time, standard deviation of forces, and number of significant catheter contacts with the arterial wall were extracted. Results Overall, median CF were reduced from 1.20 N (interquartile range IQR, 0.98-1.56 N) to 0.31 N (IQR, 0.26-0.40 N; P < .001) for the right common carotid artery; 1.59 N (IQR, 1.11-1.85 N) to 0.33 N (IQR, 0.29-0.43 N; P < .001) for the left common carotid artery; and 0.84 N (IQR, 0.47-1.08 N) to 0.10 N (IQR, 0.07-0.17 N; P < .001) for the left subclavian artery. Robotic navigation resulted in significant reductions for the mean and maximum forces for each procedural phase. Significant improvements were also seen in other metrics, particularly at the target vessel ostium and for the more anatomically challenging procedural phases. Force reductions using robotic technology were evident for both novice and expert groups. Conclusions Robotic navigation can potentially reduce CF and catheter-tissue contact points in an in vitro model, by enhancing catheter stability and control during endovascular manipulation.
Purpose
To investigate the quality of stent-graft fenestrations created in vitro
using different needle puncture and balloon dilation angles in different
commercial endografts.
Methods
Fenestrations ...were made in a standardized fashion in 3 different endograft
types: Talent monofilament twill woven polyester, Zenith multifilament
tubular woven polyester, and Endofit thin-walled expanded
polytetrafluoroethylene (PTFE). Punctures were made at 30°,
60°, and 90° angles using a 20-G needle and dilated using 6-mm
standard and 7-mm cutting balloons; at least 6 fenestrations were made at
each angle with standard balloons and at least 6 with cutting balloons. The
137 fenestrations were examined under light microscopy; quantitative and
qualitative digital image analysis was performed to determine size, shape,
and fenestration quality.
Results
PTFE grafts were easier to puncture/dilate, resulting in larger, elliptical
fenestrations with overall better quality than the Dacron grafts; however,
the puncture/dilation angle made an impact on the shape and quality of
fenestrations. A significant number of fabric tears were observed in PTFE
fabric at <90° puncture/dilation angles compared to Dacron
grafts. In Dacron grafts, fenestration quality was significantly higher with
90° puncture/dilation angles (higher in Talent grafts). Cutting
balloon use resulted in significantly more fabric tears and poor quality
fenestrations in all graft types.
Conclusion
Different endografts behave significantly differently when fenestrations are
fashioned. Optimum puncture/dilation is important when considering in vivo
fenestration techniques. Improvements in instrumentation, materials, and
techniques are required to make this a reliable and reproducible
endovascular option.
Endovascular technologies are rapidly evolving, often requiring coordination and cooperation between clinicians and technicians from diverse specialties. These multidisciplinary interactions lead to ...challenges that are reflected in the high rate of errors occurring during endovascular procedures. Endovascular virtual reality (VR) simulation has evolved from simple benchtop devices to full physic simulators with advanced haptics and dynamic imaging and physiological controls. The latest developments in this field include the use of fully immersive simulated hybrid angiosuites to train whole endovascular teams in crisis resource management and novel technologies that enable practitioners to build VR simulations based on patient-specific anatomy. As our understanding of the skills, both technical and nontechnical, required for optimal endovascular performance improves, the requisite tools for objective assessment of these skills are being developed and will further enable the use of VR simulation in the training and assessment of endovascular interventionalists and their entire teams. Simulation training that allows deliberate practice without danger to patients may be key to bridging the gap between new endovascular technology and improved patient outcomes.
Objective The objective of this study is to examine contemporary management of primary mycotic aortic aneurysms in a single center. We have previously reported the management of mycotic aortic ...aneurysms in 15 patients between 1991 and 2001, and we hypothesized that management would change in the light of the evolution of endovascular aortic repair. Methods A review of a prospectively collected database (2002-2009) of all patients presenting with mycotic aneurysms. Results A total of 19 aneurysms were identified in 17 patients (12 men, 5 women) with a median age of 66.2 years (range, 49-82 years). All were symptomatic, and nine had contained rupture. There were five infrarenal, two juxtarenal, three Crawford type III, four type IV thoracoabdominal aortic aneurysms, and five descending thoracic aneurysms in the series. All thoracic aneurysms were excluded by thoracic endovascular aneurysm repair. Two patients underwent visceral hybrid endografting for type III thoracic aortic aneurysm; the third was treated with open repair. Four patients underwent open type IV repair. Two of the infrarenal aneurysms were treated with bifurcated endovascular aneurysm repair, and the other three and both juxtarenals with open repair with in situ reconstruction. There were three early (17.6%) and three late deaths (17.6%). The median follow-up was 30.5 months (range, 1-102 months). Conclusions The results of the latest series show that open surgery is still required in many cases. The introduction of endovascular techniques in the exclusion of mycotic aneurysms can be accomplished with acceptable results, and endovascular treatment has increased the therapeutic options for a difficult condition.
We review our ongoing experience with a transabdominal stent repair of complex thoracoabdominal aneurysms (Crawford type I, II, and III) with surgical revascularization of visceral and renal ...arteries.
A retrospective review was conducted of prospectively collected data from 29 consecutive patients who underwent an attempted visceral hybrid procedure between January 2002 and April 2005. Twenty-two patients were elective, four were urgent (symptomatic), and three were emergent (true rupture). The median patient age was 74 years (range, 37 to 81 years). The aneurysms were Crawford type I in 3, type II in 18, type III in 7, and type IV in 1. Previous aortic surgery had been performed in 13 (45%) of 29 and included aortic valve and root replacement in 3, TAA repair in 1, type I repair in 1), type IV repair in 3, type B dissection in 2, infrarenal aneurysm in 5, and right common iliac aneurysm in 1. Severe preoperative comorbidity was present in 23 (80%) of 29: chronic renal impairment in 5, severe chronic obstructive pulmonary disease in 6, myocardial disease in 11 at New York Heart Association grade II (6) and grade III (5), and Marfan’s syndrome in 6. Twenty-six patients (90%) had a completed procedure. In two patients, myocardial instability prevented completion of the procedure despite extensive preoperative cardiac assessment, and in one, poor flow in the true lumen of a chronic type B dissection prevented anastomosis of the revascularization grafts. Exclusion of the full thoracoabdominal aorta was achieved in all 26 completed procedures and extended to include the iliac arteries in four, with revascularization of coeliac in 26, superior mesenteric artery in 26, left renal artery in 21, and right renal artery in 21).
There was no paraplegia ≤30 days or during inpatient admission, and elective and urgent mortality was 13% (3/23). All of the patients with ruptured thoracoabdominal aneurysms died ≤30 days. Major complications included prolonged respiratory support (>5 days) in 9, inotropic support in 4, renal impairment requiring temporary support in 2 and not requiring support in 2, prolonged ileus in 2, resolved left hemispheric stroke in 1, and resection of an ischemic left colon in 1. Median blood loss was 3.9 liters (range, 1.2 to 13 liters). The median ischemia time was 15 minutes (range, 13 to 27 minutes) for the superior mesenteric and coeliac arteries and 15 minutes for the renal arteries (range, 13 to 21 minutes). The median hospital stay was 27 days (range, 16 to 84 days). Follow-up was a median of 8 months (range, 2 to 31 months), with 92 of 94 grafts patent. Six patients were found to have a type I endoleak. In four, this was a proximal leak, and stent extension in three reduced, but did not cure, the endoleak. One patient with a distal type I endoleak was successfully treated by embolization. Four type II endoleaks resolved without intervention, and one was treated by occlusion coiling of the origin of the left subclavian artery. A single late type III endoleak was found.
Early results of visceral hybrid stent-grafts for types I, II, and III thoracoabdominal aneurysms are encouraging, with no paraplegia in this particularly high-risk group of patients. These results have encouraged us to perform the new procedure, in preference to open surgery, in Crawford type I, II, and III thoracoabdominal aortic aneurysms.
A 67-year-old man underwent robot-assisted three-vessel fenestrated endovascular aneurysm repair (FEVAR) for a 7.3-cm juxtarenal aneurysm. The 6-F robotic catheter was manipulated from a remote ...workstation, away from the radiation source. Robotic cannulation of the left renal artery was achieved within 3 minutes. System setup time was 5 minutes. There were no postoperative complications. Computed tomography angiography performed at discharge and at 4-month follow-up confirmed target vessel patency with no evidence of an endoleak. Selective cannulation of target vessels during FEVAR using this novel technology is feasible. Endovascular robotics may have a role in simplifying complex endovascular tasks and potentially reducing radiation exposure to the operator.
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