Silicone Vessel Research Articles

Development of a patient-specific model of the human coronary system for percutaneous transluminal coronary angioplasty balloon catheter training and testing

BackgroundTo treat stenosed coronary arteries, percutaneous transluminal coronary angioplasty (PTCA) balloon catheters must combine pushability, trackability, crossability, and rewrap behavior. The existing anatomic track model (ASTM F2394) for catheter testing lacks 3D morphology, vessel tortuosity, and compliance, making evaluating performance characteristics difficult. This study aimed to develop a three-dimensional patient-specific phantom (3DPSP) for device testing and safe training for interventional cardiologists.MethodsA range of silicone materials with different shore hardnesses (00–30–45 A) and wall thicknesses (0.5 mm, 1 mm, 2 mm) were tested to determine compliance for creating coronary vessel phantoms. Compliance was assessed using optical coherence tomography (OCT) and compared to values in the literature. Stenosis was induced using multilayer casting and brushing methods, with gypsum added for calcification. The radial tensile properties of the samples were investigated, and the relationship between Young’s modulus and compliance was determined. Various methods have been introduced to approximate the friction between silicone and real coronary vessel walls. Computerized tomography (CT) scans were used to obtain patient-specific anatomy from the femoral artery to the coronary arteries. Artery lumens were segmented from the CT scans to create dissolvable 3D-printed core models.ResultsA 15A shore hardness silicone yielded an experimental compliance of 12.3–22.4 mm2mmHg·103\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{m{m}^{2}}{mmHg}\\cdot {10}^{3}$$\\end{document} for stenosed tubes and 14.7–57.9 mm2mmHg·103\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{m{m}^{2}}{mmHg}\\cdot {10}^{3}$$\\end{document} for uniform tubes, aligning closely with the literature data (6.28–40.88 mm2mmHg·103\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{m{m}^{2}}{mmHg}\\cdot {10}^{3}$$\\end{document}). The Young’s modulus ranged from 43.2 to 75.5 kPa and 56.6–67.9 kPa for the uniform and calcified materials, respectively. The dependency of the compliance on the wall thickness, Young’s modulus, and inner diameter could be shown. Introducing a lubricant reduced the silicone friction coefficient from 0.52 to 0.13. The 3DPSP was successfully fabricated, and comparative analyses were conducted among eight commercially available catheters.ConclusionThis study presents a novel method for crafting 3DPSPs with realistic mechanical and frictional properties. The proposed approach enables the creation of comprehensive and anatomically precise setups spanning the right femoral artery to the coronary arteries, highlighting the importance of such realistic environments for advancing medical device development and fostering safe training conditions.

A simple, novel technique to create silicone vessels for microsurgical training

Background and objectivesEffective microsurgical training necessitates dedicated practice, prompting the development of simulation models that mitigate the hygiene risks, regulatory challenges, and storage difficulties associated with conventional biological models. This study aims to evaluate the preferences of microsurgeons and medical students regarding self-made silicone simulation vessels, comparing them to standard biological models. MethodsA three-part jig, comprising of a two-part metal clamp component and a transparent acrylic block with 4x4 channels, was designed. This assembly produced 16 vessels with a 1 ​mm inner diameter. Liquid silicone (Ecoflex 00–30), readily accessible from online distributors, was injected into the channels using a syringe. After tightening the clamp component and inserting 16 1 ​mm k-wires, the vessels were left to set for approximately 24 ​h 20 medical students with no prior microsurgical experience and 10 microsurgery-trained surgeons then evaluated these silicone vessels against a commonly used biological model (chicken brachial artery for surgeons or chicken aorta for students). Participants were then surveyed about their preference for a specific model for frequent practice using a 10-point Likert scale. Results and conclusionIn assessing ideal microsurgical training models, all participants highlighted the importance of realism. Surgeons’ main practical considerations were hygiene, availability, and setup and storage ease, while medical students were primarily concerned with cost-effectiveness. Both surgeons and medical students perceived the biological model as more realistic, yet less hygienic and harder to set up and store. Conversely, the silicone model, though deemed less realistic, offered advantages in hygiene, availability, cost-effectiveness, and setup and storage simplicity. The silicone model emerged as the overall favorite amongst all participants for frequent practice. Silicone vessels may serve as a complementary adjunct to biological models, allowing surgeons-in-training to practice their skills outside of the operating room and lab settings.

Ideal suturing technique for robot-assisted microsurgical anastomoses

The development of novel robotic devices specifically designed for open microsurgery leads to increasing applications in reconstructive procedures. While initial studies revealed improved precision and surgical ergonomics upon robotic assistance, surgical time was consistently observed to be increased. This study compares two robotic suturing techniques using the Symani Surgical System and RoboticScope in a preclinical setting, to further leverage the benefits of novel robotic devices in microsurgery. Six experienced microsurgeons performed three microvascular anastomoses with a “steady-thread” suturing technique and a “switch-thread” technique on 1.0-mm-diameter artificial silicone vessels. Time for anastomosis and participant’s satisfaction with the techniques and robotic setup were recorded. Anastomosis quality and microsurgical skills were assessed using the Anastomosis Lapse Index and Structured Assessment of Microsurgery Skills. Lastly, technical error messages and thread ruptures were quantified. Knot tying was significantly faster and evaluated significantly better by participants using the steady-thread technique (4.11 ± 0.85 vs. 6.40 ± 1.83 min per anastomosis). Moreover, microsurgical skills were rated significantly better using this technique, while both techniques consistently led to high levels of anastomosis quality (2.61 ± 1.21 vs. 3.0 ± 1.29 errors per anastomosis). In contrast, the switch-thread technique was associated with more technical error messages in total (14 vs. 12) and twice as many unintended thread ruptures per anastomosis (1.0 ± 0.88 vs. 0.5 ± 0.69). This study provides evidence for the enhanced performance of a steady-thread suturing technique, which is suggested to be applied upon robot-assisted microsurgical procedures for optimized efficiency.

Preclinical Performance of the Combined Application of Two Robotic Systems in Microsurgery: A Two-center Study.

Recent advancements in the development of robotic devices increasingly draw the attention toward the concept of robotic microsurgery, as several systems tailored to open microsurgery are being introduced. This study describes the combined application of a novel microsurgical robot, the Symani, with a novel robotic microscope, the RoboticScope, for the performance of microvascular anastomoses in a two-center preclinical trial. Six novices, residents, and experienced microsurgeons (n = 18) performed five anastomoses on 1.0-mm-diameter silicone vessels with a conventional versus combined robotic approach, resulting in 180 anastomoses. Microsurgical performance was evaluated, analyzing surgical time, subjective satisfaction with the anastomosis and robotic setup, anastomosis quality using the anastomosis lapse index score, microsurgical skills using the Structured Assessment of Microsurgery Skills score, and surgical ergonomics using the Rapid Entire Body Assessment score. All participants significantly improved their performance during the trial and quickly adapted to the novel systems. Surgical time significantly decreased, whereas satisfaction with the anastomosis and setup improved over time. The use of robotic systems was associated with fewer microsurgical errors and enhanced anastomosis quality. Especially novices demonstrated accelerated skill acquisition upon robotic assistance compared with conventional microsurgery. Moreover, upper extremity positioning was significantly improved. Overall, the robotic approach was subjectively preferred by participants. The concept of robotic microsurgery holds great potential to improve precision and ergonomics in microsurgery. This two-center trial provides promising evidence for a steep learning curve upon introduction of robotic microsurgery systems, suggesting further pursuit of their clinical integration.

Customisable Silicone Vessels and Tissue Phantoms for In Vitro Photoplethysmography Investigations into Cardiovascular Disease.

Age-related vessel deterioration leads to changes in the structure and function of the heart and blood vessels, notably stiffening of vessel walls, increasing the risk of developing cardiovascular disease (CVD), which accounts for 17.9 million global deaths annually. This study describes the fabrication of custom-made silicon vessels with varying mechanical properties (arterial stiffness). The primary objective of this study was to explore how changes in silicone formulations influenced vessel properties and their correlation with features extracted from signals obtained from photoplethysmography (PPG) reflectance sensors in an in vitro setting. Through alterations in the silicone formulations, it was found that it is possible to create elastomers exhibiting an elasticity range of 0.2 MPa to 1.22 MPa. It was observed that altering vessel elasticity significantly impacted PPG signal morphology, particularly reducing amplitude with increasing vessel stiffness (p < 0.001). A p-value of 5.176 × 10-15 and 1.831 × 10-14 was reported in the red and infrared signals, respectively. It has been concluded in this study that a femoral artery can be recreated using the silicone material, with the addition of a softener to achieve the required mechanical properties. This research lays the foundation for future studies to replicate healthy and unhealthy vascular systems. Additional pathologies can be introduced by carefully adjusting the elastomer materials or incorporating geometrical features consistent with various CVDs.

125 Relationship of electrical conductivity to color variables (chroma, hue, L*, a*, b*) of fresh beef loins

Abstract Appraisal of beef color and overall quality assessment by consumers may be variable. In this study, Prime Grade beef strip loins were used to determine if electrical conductivity measurements (ECM) are correlated with color variables (chroma, hue, L*, a*, and b*) and could be used to improve color quality assessment and evaluation. An experimental design consisting of 6 full strip loins x 6 steaks per loin x 2 locations per steak was used and provided 72 total observations for analysis. Electrical conductivity measurements (ECM) procedures developed in our lab consisted of using emulsified meat samples concealed in silicon vessel connected to copper electrodes leading to a digital multimeter. ECM was measured in microsiemens (µS) over 60 sec with a sampling rate of 2/sec. Color variables were measured using a Varian Cary 50 Series Spectrophotometer following procedures of AMSA to ensure standardization. Data were analyzed using ANOVA and Pearson correlation coefficients. ECM means in microsiemens (µS) were 14.37, 42.52, 34.86, 22.89, 16.05, and 24.70 for the six groups of fresh steaks and were not different (P &amp;gt; 0.05). However, ECM values for cooked steaks differed (P &amp;lt; 0.05). Mean values for chroma, hue, L*, a*, and b* were different (P &amp;lt; 0.05) across fresh loin steaks. Correlations of ECM to all five of the color variables were different and negative (P &amp;lt; 0.05): chroma -0.013, hue -0.050, L* -0.009, a *-0.031, b* -0.110. These data show that ECM provide another analytical procedure that may be used in evaluating the color of fresh beef loins, and in the overall assessment and evaluation of beef products.

Evaluation of intracranial stenting in a simulated training and assessment environment for neuroendovascular procedures.

Given the inherent complexity of neurointerventional procedures and the associated risks of ionizing radiation exposure, it is crucial to prioritize ongoing training and improve safety protocols. The aim of this study is to assess a training and evaluation in-vitro environment using a vascular model of M1 stenosis, within a clinical angiography suite, without relying on animal models or X-ray radiation. Using a transparent model replicating M1 stenosis, we conducted intracranial stenting procedures with four different setups (Gateway & Wingspan, Gateway & Enterprise, Neurospeed & Acclino, and Pharos Vitesse). A video camera was integrated with the angiography system's monitor for real-time visualization, while a foot switch was employed to simulate live fluoroscopy. Three neuroradiologists with varying levels of expertise performed each procedure for three times. The total duration of fluoroscopy as well as the time from passing the stenosis with the wire to completion of the procedure were recorded using a dedicated software designed for this experimental setup. Compared to the Gateway & Wingspan procedure, the total fluoroscopy time reduced significantly with the Gateway & Enterprise, Neurospeed & Acclino, and Pharos Vitesse procedures by 51.56 s, 111.33 s, and 144.89 s, respectively (p < 0.001). Additionally, physicians with under 2 years and over 5 years of experience reduced FT by 62.83 s and 106.42 s, respectively, (p < 0.001), compared to a novice physician. Similar trends were noted for the time of wire distal to stenosis, with significant reductions for Neurospeed & Acclino and Pharos Vitesse compared to both Gateway & Wingspan as well as Gateway & Enterprise (all p < 0.001). Procedures requiring wire exchange maneuvers exhibited nearly twice the fluoroscopy time in comparison to balloon-mounted stenting or stent-placement via PTA balloon catheters. The more experienced neuroradiologist demonstrated significantly quicker performance in line with expectations in a real-life clinical setting, when compared to the less experienced interventionalist. This in-vitro setup allowed the evaluation of alternative technical approaches and differences in experience of operators without the use of animal models or X-ray. The setup combines advantages of simulators and silicone vessel models in a realistic working environment.

Evaluation of vessel injury after simulated catheter use in an endothelialized silicone model of the intracranial arteries.

Neurothrombectomy catheters can disrupt or injure the vessel wall. This potential injury is often studied in animal or cadaver models, but prior work suggests that endothelialized silicone models may be an option for early in vitro assessment. The purpose of this work was to create a complex, clinically-relevant endothelialized neurovascular silicone model, and to determine the utility of the model for evaluating vessel injury due to catheter simulated use. Models of the ICA and MCA were fabricated out of silicone, sterilized, coated with fibronectin, placed in bioreactors, and endothelialized with HUVECs. These silicone vessels were maintained under flow for 3 and 7 days, and cellular linings were assessed. Subsequently, 24 silicone vessels were created and treated with neurovascular catheters. Vessels were accessed with a guidewire, microcatheter, and/or aspiration catheter, either once (1-pass) or three times (3-pass). Vessels were then fixed, and injury was evaluated through quantitative image analysis and a visual scoring system. Complex silicone models were successfully endothelialized and maintained with consistent cell linings. The transparent silicone permitted catheter simulated use without fluoroscopy, and injury to the vessel wall was observed and successfully imaged and characterized. Vessels subjected to 3-passes exhibited more injury than 1-pass, and injury increased with the number and size of devices. These results illustrated expected trends and support use of these models for early assessment of vessel injury. Complex silicone neurovascular models can be endothelialized and used in vitro to assess and compare injury due to the use of neurovascular catheters.

231 Electrical Conductivity, Color, and Tenderness Values of Fresh and/or Cooked Beef

Abstract A study with fresh and cooked beef loins, beef jerky, and water types was conducted to evaluate electrical conductivity (EC) measurements as a procedure in quality appraisal. Six full strip loins x 6 steaks per loin x 2 types provided 72 electrical conductivity (CV) observations, and 72 measurements of color variables (chroma, hue, L*, a* b*) of loins. Six core samples per cooked steaks provided 216 Warner-Bratzler shear force (WBSF) values. EC was also measured on three water types and saline (n=20), and commercial beef jerky samples (n=72). Procedures used for EC were developed in our lab and consisted of using emulsified samples enclosed in a silicon vessel with copper electrodes connected to a digital multimeter. Microsiemens (µS) were measured over 60 s with a sampling rate of two per s. Color variables were measured using a Varian Cary 50 Series Spectrophotometer. Data were analyzed using ANOVA and Pearson correlation coefficients. EC means (µS) were 14.4, 42.5, 34.9, 22.9, 16.1 and 24.7 for fresh steaks (P= .07); and 7.8, 16.5, 6.4, 10.7, 5.2, and 8.0 for cooked steaks (P=.36). Means for all color variables were different (P&amp;lt; 0.05) across fresh steaks. Correlation of EC to each color variable was negative: chroma -0.013, hue -0.050, L*-0.009, a*-0.131, b*-0.110. Only a* was significantly correlated (P&amp;lt; 0.05) to EC. WBSF tenderness (kg/f) means were not different (P &amp;gt; 0.05) across steaks but did differ (P&amp;lt; 0.05) within steaks. Correlations of EC to tenderness was not significant (P &amp;gt; 0.05). EC mean of beef jerky was 106.9 (SEM 5.05). EC of water types differed (P&amp;lt; 0.05) - deionized 0.40, purified 1.56, tap 1.30. EC for saline was 0.04. These data indicate that EC of beef can be effectively measured, but high variations across EC, color, and tenderness values decreased the overall probability of finding relationships.

Framework for patient-specific simulation of hemodynamics in heart failure with counterpulsation support.

Despite being responsible for half of heart failure-related hospitalizations, heart failure with preserved ejection fraction (HFpEF) has limited evidence-based treatment options. Currently, a substantial clinical issue is that the disease etiology is very heterogenous with no patient-specific treatment options. Modeling can provide a framework for evaluating alternative treatment strategies. Counterpulsation strategies have the capacity to improve left ventricular diastolic filling by reducing systolic blood pressure and augmenting the diastolic pressure that drives coronary perfusion. Here, we propose a framework for testing the effectiveness of a soft robotic extra-aortic counterpulsation strategy using a patient-specific closed-loop hemodynamic lumped parameter model of a patient with HFpEF. The soft robotic device prototype was characterized experimentally in a physiologically pressurized (50–150 mmHg) soft silicone vessel and modeled as a combination of a pressure source and a capacitance. The patient-specific model was created using open-source software and validated against hemodynamics obtained by imaging of a patient (male, 87 years, HR = 60 bpm) with HFpEF. The impact of actuation timing on the flows and pressures as well as systolic function was analyzed. Good agreement between the patient-specific model and patient data was achieved with relative errors below 5% in all categories except for the diastolic aortic root pressure and the end systolic volume. The most effective reduction in systolic pressure compared to baseline (147 vs. 141 mmHg) was achieved when actuating 350 ms before systole. In this case, flow splits were preserved, and cardiac output was increased (5.17 vs. 5.34 L/min), resulting in increased blood flow to the coronaries (0.15 vs. 0.16 L/min). Both arterial elastance (0.77 vs. 0.74 mmHg/mL) and stroke work (11.8 vs. 10.6 kJ) were decreased compared to baseline, however left atrial pressure increased (11.2 vs. 11.5 mmHg). A higher actuation pressure is associated with higher systolic pressure reduction and slightly higher coronary flow. The soft robotic device prototype achieves reduced systolic pressure, reduced stroke work, slightly increased coronary perfusion, but increased left atrial pressures in HFpEF patients. In future work, the framework could include additional physiological mechanisms, a larger patient cohort with HFpEF, and testing against clinically used devices.

Polymer Coating Integrity, Thrombogenicity and Computational Fluid Dynamics Analysis of Provisional Stenting Technique in the Left Main Bifurcation Setting: Insights from an In-Vitro Model.

Currently, the provisional stenting technique is the gold standard in revascularization of lesions located in the left main (LM) bifurcation. The benefit of the routine kissing balloon technique (KBI) in bifurcation lesions is still debated, particularly following the single stent treatment. We compared the latest-generation drug-eluting stent (DES) with no side branch (SB) dilatation “keep it open” technique (KIO) vs. KBI technique vs. bifurcation dedicated drug-eluting stent (BD-DES) implantation. In vitro testing was performed under a static condition in bifurcation silicone vessel models. All the devices were implanted in accordance with the manufacturers’ recommendations. As a result, computational fluid dynamics (CFD) analysis demonstrated a statistically higher area of high shear rate in the KIO group when compared to KBI. Likewise, the maximal shear rate was higher in number in the KIO group. Floating strut count based on the OCT imaging was significantly higher in KIO than in KBI and BD-DES. Furthermore, according to OTC analysis, the thrombus area was numerically higher in both KIO and KBI than in the BD-DES. Scanning electron microscopy (SEM) analysis shows the highest degree of strut coating damage in the KBI group. This model demonstrated significant differences in CFD analysis at SB ostia with and without KBI optimization in the LM setting. The adoption of KBI was related to a meaningful reduction of flow disturbances in conventional DES and achieved results similar to BD-DES.

In Vitro Study of Endothelial Cell Morphology and Gene Expression in Response to Wall Shear Stress Induced by Arterial Stenosis.

Objectives: We examined the correlation between changes in hemodynamic characteristics induced by arterial stenosis and vascular endothelial cell (EC) morphology and gene expression in straight silicone arteries. Materials and methods: Transparent silicone straight artery models with four degrees of stenosis (0, 30, 50, and 70%) were fabricated. Particle image velocimetry was performed to screen silicone vessel structures with good symmetry and to match the numerical simulations. After the inner surface of a symmetric model was populated with ECs, it was perfusion-cultured at a steady flow rate. A computational fluid dynamics (CFD) study was conducted under the same perfusion conditions as in the flow experiment. The high-WSS region was then identified by CFD simulation. EC morphology in the high-WSS regions was characterized by confocal microscopy. ECs were antibody-stained to analyze the expression of inflammatory factors, including matrix metalloproteinase (MMP)-9 and nuclear factor (NF)-κB, which were then correlated with the CFD simulations. Results: As the degree of vascular stenosis increases, more evident jet flow occurs, and the maximum WSS position moves away first and then back. ECs were irregularly shaped at vortex flow regions. The number of gaps between the cells in high-WSS regions increased. The MMP-9 and NF-κB expression did not differ between vessels with 30 and 0% stenosis. When arterial stenosis was 70%, the MMP-9 and NF-κB expression increased significantly, which correlated with the regions of substantially high WSS in the CFD simulations. Conclusion: Stenotic arteries induce hemodynamic stress variations, which contribute to differences in EC morphology and gene expression. A high degree of vascular stenosis can directly increase inflammatory factor expression.

The Influence of Experience on Gazing Patterns during Endovascular Treatment: Eye-Tracking Study.

In various fields, differences in eye-gazing patterns during tasks between experts and novices have been evaluated. The aim of this study was to investigate gazing patterns during neuro-endovascular treatment using an eye-tracking device and assess whether gazing patterns depend on the physician's experience or skill. Seven physicians performed coil embolization for a cerebral aneurysm in a silicone vessel model under biplane X-ray fluoroscopy, and their gazing patterns were recorded using an eye-tracking device. The subjects were divided into three groups according to experience, highly experienced (Expert) group, intermediately experienced (Trainee) group, and less experienced (Novice) group. The duration of fixation on the anterior-posterior (AP) view screen, lateral (LR) view, and out-of-screen were compared between each group. During microcatheter navigation, the Expert and Trainee groups spent a long time on fixation to AP, while the Novice group split their attention between each location. In coil insertion, the Expert group gazed at both the AP and the LR views with more saccades between screens. In contrast, the Trainee group spent most of their time only on the AP view screen and the Novice group spent longer out-of-screen. An eye-tracking device can detect different gazing patterns among physicians with several experiences and skill levels of neuroendovascular treatment. Learning the gazing patterns of experts using eye tracking may be a good educational tool for novices and trainees.

Validation of a Microsurgery Simulation for Use in an Oral and Maxillofacial Surgery Training Curriculum

BackgroundApplications of microsurgery are evolving and expanding within oral and maxillofacial surgery (OMS).1 While a variety of surgical subspecialties are embracing microsurgery as a core component of their training programs, a validated microsurgery curriculum in the OMS specialty is lacking. Microsurgery requires fine motor skills developed with consistent practice and frequent exposure, which is ideally obtained early in training and developed over time and experience. Unfortunately, many barriers exist that limit residents from achieving early exposure and competence in microsurgery upon residency graduation.2 The objective of this study was to evaluate 2 low-cost microscopes and 2 simulation vessels for use in a training curriculum. The primary outcome was readiness of the simulation to be used in a microsurgical curriculum. Secondary outcomes were realism, value, usefulness, difficulty, and cost of the simulation. MethodsA microvascular anastomosis simulation exercise was developed. Seven surgeons were tasked with completing an end-to-end anastomosis on both a silicone vessel and a chicken thigh femoral artery vessel on 2 table-top microscopes. These microscopes were a monocular digital microscope (Plugable USB 2.0 Digital Microscope) and a binocular stereo microscope (AmScope 7x-45x Stereo Binocular Microscope). The surgeons comprising the expert panel were all microvascular-trained surgeons in the departments of oral and maxillofacial surgery (n = 5), plastic and reconstructive surgery (n = 1), and otolaryngology (n = 1). The surgeons performed the simulation independently, without an assistant. Upon completion of the simulation, the surgeons were asked to complete a survey to evaluate the simulation across multiple domains. Likert responses were coded into numeric values (e.g., “strongly disagree” = 1, “somewhat disagree” = 2, etc.), and means and standard deviations were reported. Paired T-tests were used to compare responses to analogous questions regarding the microscopes and simulation vessels. Analyses were performed in SAS V9.4 (SAS Institute Inc., Cary, NC, USA). ResultsSeven surgeons completed the simulation exercise and survey. The stereo microscope simulation scored significantly higher in “readiness for use” in a microsurgery curriculum than the digital microscope (P = .002). All 7 surgeons indicated that the stereo microscope simulation, in conjunction with silicone and chicken vessels, could be used in a microsurgery curriculum in its current state (n = 4) or with minimal modification (n = 3). All 7 respondents indicated that the digital microscope simulation required considerable modification (n = 4) or extensive modification with re-evaluation (n = 3) before use. The stereo microscope significantly outperformed the digital microscope in depth perception (P < .001), field of view (P = .038), lighting (P = .038), and clarity (P = .030). The respondents strongly agreed that the binocular microscope was a low-cost and high-value training simulation (mean: 4.86 out of 5.00, SD = 0.38). Both microscopes were “very useful” for practicing microsurgical technique, allowing early access to training and improving hand-eye coordination. The chicken vessel significantly outperformed the silicone vessel in realism of tissue handling (P < .001), passing the needle (P = .007), vessel orientation (P = .035), and knot-tying (P = .005). ConclusionA microsurgical training curriculum using the stereo or digital table-top microscopes in conjunction with chicken thigh or silicone vessels demonstrates value for OMS residency education, with the stereo microscope and the chicken thigh outperforming their counterparts. The microsurgery simulation is a low-cost, high-value option that is ready for use in microsurgery training.

Remote Surgery Using a Neuroendovascular Intervention Support Robot Equipped with a Sensing Function: Experimental Verification.

Purpose:Expectations for remote surgery in endovascular treatments are increasing. We conducted the world's first remote catheter surgery experiment using an endovascular treatment-supported robot. We considered the results, examined the issues, and suggested countermeasures for practical use.Methods:The slave robot in the angiography room is an original machine that enables sensing feedback by using an originally developed insertion force-measuring device, which detects the pressure stress on the vessel wall and alerts the operator using an audible scale. The master side was set in a separate room. They were connected via HTTP communication using local area network system. The surgeon operated by looking at a personal computer monitor that shared an angiography monitor. The slave robot catheterized and inserted a coil for an aneurysm in the silicon blood vessel model in the angiography room.Results:Our robot responded to the surgeon's operations promptly and to the joystick's swift movements quite accurately. The surgeon could control the stress to the model vessels using various actions, because the operator could hear the sound from the insertion force. However, the robot required a time gradient to reach a stable advanced speed at the time of the initial movement, and experienced a slight time lag.Conclusion:Our remote operation appeared to be sufficiently feasible to perform the surgery safely. This system seems extremely promising for preventing viral infection and radiation exposure to medical staff. It will also enable medical professionals to operate in remote areas and create a ubiquitous medical environment.

A Novel Silicone Simulation Model for Microvascular Anastomosis.

Purpose:Surgical simulation of microvascular anastomosis has become increasingly popular. There are several living and silicone models available. Current silicone models fail to accurately reproduce a vessel’s loose adventitial layer, which may lead to the development of improper microsurgical technique. Our purpose is to create a realistic 3-dimensional microsurgical simulator that incorporates an adventitial vessel layer for higher fidelity manipulation of vessels.Methods:A microvascular anastomosis simulator was manufactured using metal moulds and inorganic materials. Synthetic tubing was created with a metal cylinder, 1.65 mm in diameter, painted with 2 sequential layers of silicon with a shore hardness of 2A. Silicone was allowed to fully cure in-between layers. Vessel adventitia was created with a 100-micron polyester mesh adhered to the silicone vessel exterior. Once dry, the synthetic tube is removed from the metal cylinder is then clipped to reveal the inner lumen. Both Resident and attending physicians evaluated the model with and without the adventitial layer and completed a questionnaire.Results:Grasping and manipulation of the vessel were scored on Average score 4.5 and 3 out of 5, with adventitia and without, respectively (P = .00906). Usefulness as a teaching tool was scored on average 4.9 and 4.2, with adventitia and without, respectively (P = .0232). The analysis included: simulation realism, educational utility, and overall satisfaction. Responses in all domains were favourable, suggesting the utility of this model.Conclusion:We created a realistic, high fidelity microvascular anastomosis simulator that is low cost and easily reproducible. Initial feedback is encouraging regarding realism, educational utility, and overall usefulness. Further validation is required to assess its effectiveness in resident education and skill transfer to the operating room.

Factors related to microcatheter passage through the trans-cell approach using a low-profile visualized intraluminal support device: an in-vitro study

Background and purposeThe trans-cell approach using a low-profile visualized intraluminal support (LVIS) device is sometimes used for aneurysm coil embolization. However, factors related to microcatheter passage remain uninvestigated. We aimed to examine in-vitro factors related to microcatheter passage using the trans-cell approach with an LVIS. MethodsSilicone vessel models (inner diameter, 4 mm) were created with different bend segments and a 4-mm hole assuming an aneurysm neck on the side of the greater curvature. The LVIS Blue (4.5 × 32 mm) was deployed at the bend segment, and passability on the trans-cell surface was evaluated by passing the microcatheter along the micro guidewire. A total of 800 passage experiments were performed using two types of microcatheter, ten types of silicone vessel, four cell widths, five cells with the same LVIS device, and two micro guidewire directions in the aneurysm. ResultsThe Headway Duo microcatheter (35.5%, 142/400) tended to have better passability compared with the Headway 17 microcatheter (29.3%, 117/400) (p = 0.070). As the cell width and angle between the trans-cell surface and microcatheter direction increased, passability significantly increased (p = 0.027 and p < 0.001, respectively). There was no significant difference in passability when the micro guidewire was directed to the proximal side versus the distal side (p = 0.45). ConclusionsA large cell width and an obtuse angle between the trans-cell surface and microcatheter direction facilitated good passability. Although statistically marginal, microcatheters with small ledges and small tips had relatively good passability.

Endothelialized silicone aneurysm models for in vitro evaluation of flow diverters

ObjectiveThe goal of this work was to endothelialize silicone aneurysm tubes for use as in vitro models for evaluating endothelial cell interactions with neurovascular devices. The first objective was to...

Superficial Temporal Artery–Middle Cerebral Artery Bypass Ex Vivo Hybrid Simulator: Face, Content, Construct, and Concurrent Validity

Cerebrovascular bypass surgical procedures require highly developed dexterity and refined bimanual technical skills. To attain such a level of prowess, neurosurgeons and residents have traditionally relied on "flat" models (without depth of field), such as chicken wings, live rats, silicone vessels, and other materials that stray far from the reality of the operating room, albeit more accessible. We have explored the use of a hybrid exvivo simulator that takes advantage of the availability of placenta vessels and retains the complexity of surgery performed on a human skull to create a more realistic method for the development of cerebrovascular bypass surgical skills. Twelve exvivo simulators were constructed using 3 human placentas and 1 synthetic human skull for each. Face, content, construct, and concurrent validity were assessed by 12 neurosurgeons (6 trained vascular surgeons and 6 general neurosurgeons) and compared with those of other bypass models. The fidelity grade was ranked as low (Linkert scale score, 1-2), medium (score, 3), and high (score, 4-5). The face and content validity of the model showed high fidelity to superficial temporal artery-middle cerebral artery bypass surgery. Construct validity showed that cerebrovascular neurosurgeons had better performance, and concurrent validity highlighted that all surgical steps were present. The simulator was found to have strong face and content, construct, and concurrent validity for microsurgical cerebrovascular training, allowing for simulation of all surgical steps of the bypass procedure. The hybrid simulator seems to be a promising method for shortening the bypass surgery learning curve. However, more studies are required to evaluate the predictive validity of the model.

Use of Polyvinyl Alcohol Sponge Cubes for Vagal Nerve Stimulation: A Suggestion for the Wrapping Step. Technical Note and Step-by-Step Operative Technique.

BACKGROUNDVagal nerve stimulation (VNS) is an approved treatment for epilepsy and depression. Wrapping the helical electrodes around the nerve can prove technically challenging. However, a quick and efficient method to slightly elevate the nerve can highly facilitate this part of the procedure.OBJECTIVETo provide useful surgical tips to facilitate the procedure.METHODSBased on experience of more than 150 adult cases for mainly epilepsy (primary lead implant), the authors share their surgical technique to provide the experienced surgeons or newcomers to the field of VNS with some useful tips. All patients signed informed consent according to the local ethics committee guidelines.RESULTSThe article consists of a detailed step-by-step description of the whole procedure illustrated through high-resolution colored photographs of the surgical field. Special reference is made to the usefulness of polyvinyl alcohol (PVA) sponge cubes to elevate the nerve instead of the commonly used silicon vessel loops.CONCLUSIONThe use of surgical microscope and PVA sponge cubes to elevate the nerve constitute key points to make VNS an easy surgery.