Simulator Training for Endovascular Neurosurgery

Simulation training is increasingly important for learning complex high-risk skills, such as endovascular neurosurgery. This endovascular neurosurgery simulator protocol tests trainees'anatomical knowledge and provides haptic catheter system feedback in a consequence-free environment. Our protocol includes stepwise guidelines for trainees of varying levels, which incorporates didactic instruction as well as a discussion of the advantages and limitations of this model.

Demonstrating the procedure will be Robert Rennert, a neurosurgery resident and former endovascular neurosurgery fellow. Before beginning a procedure, assemble and power on the simulator. Select the patient scenario in the software interface on the attached laptop and select the appropriate arterial sheath size from the dropdown menu.

Select the appropriate catheter, guidewire, and/or microsystem based on the specific scenario and turn on the A and B plane. Activate the fluoroscopy with the foot pedals and use the joysticks to adjust both the patient and image intensifier positions until the correct posteroanterior and lateral views are obtained. For a four-vessel cerebral angiogram simulation, select a five French femoral sheath, a 0.035 inch guidewire, and a five French diagnostic catheter from the dropdown menu as tools to be used in this simulation.

Insert the guidewire into the simulator machine until it registers on the simulation screen signaling that access has been gained. Advance the guidewire until it's visualized in the descending thoracic aorta and continues into the aortic arch. When the guidewire is safely in the aortic arch, hold the guidewire in place and insert a diagnostic catheter over the guidewire through the simulated femoral sheath to the aortic arch.

Remove the guidewire and gently depress the contrast syringe plunger to use the fluoroscopy puff technique to simulate contrast injection and briefly opacify the vessels as the catheter is advanced into the desired artery. Next, create a roadmap guide by injecting contrast with the contrast syringe while the roadmap fluoroscopy foot pedal is depressed. Re-insert the wire to selectively catheterize the desired vessel, advancing the catheter over the wire to catheterize the right and left internal and external carotid arteries and left and right vertebral arteries.

When each of the vessels is selectively catheterized, use the diagnostic catheter and the simulator contrast syringe to perform angiograms of each of the vessels, obtaining high magnification views of the aneurysm as necessary. Review the angiograms for adequacy before removing the catheter and remove the diagnostic catheter from the simulation sheath. For carotid terminus aneurysm coiling simulation, select a six French guide catheter, a 0.035 inch guidewire, and a four French diagnostic catheter from the dropdown menu.

Insert a diagnostic catheter over a guidewire into the aortic arch and insert a guide catheter over the diagnostic catheter through the femoral access site to the aortic arch. Remove the guidewire and create a roadmap guide of the left common carotid artery in the software. Depress the fluoroscopy foot pedal to inject contrast with the contrast syringe and re-insert the guidewire to facilitate selective catheterization of the left common carotid artery and the internal carotid artery.

When the guide catheter is within the internal carotid artery, remove the diagnostic catheter and depress the fluoroscopy pedal while injecting contrast to allow the performance of angiographic runs of the left internal carotid cerebral circulation. Measure the aneurysm using the calculation option and select a microcatheter, microwire, and an appropriately sized coil. Insert a microcatheter and microwire through the femoral access site and under roadmap guidance, selectively catheterize the aneurysm with the microsystem.

Remove the microwire. Insert the previously selected coil through the femoral access site and slowly advance the coil into the aneurysm. Once the coil is fully inserted, perform a diagnostic cerebral angiogram and assess the patency of the parent artery and aneurysm filling.

With patency of the patent artery preserved, detach the coil and remove the coil wire. Place additional coils as needed until complete embolization of the aneurysm or sufficient coverage of the dome is achieved. After a final post-coiling angiography, remove the microcatheter and guide catheter from the simulation sheath site.

For a left middle cerebral artery thrombectomy simulation, select a six French guide catheter, a 0.035 inch guidewire, and a five French diagnostic catheter from the dropdown menu. Insert the guide catheter into the left internal carotid artery and perform angiographic runs of the left internal carotid cerebral circulation as demonstrated. Select a microcatheter, a microwire, and a stent retriever device from the dropdown menu.

Insert a microcatheter and microwire into the simulated femoral access site and into the left internal carotid artery. And under roadmap guidance, advance the microwire and microcatheter into the left middle cerebral artery carefully past the area of occlusion. Replace the microwire with a stent retriever device and advance the device into the artery distal to the occlusion.

Remove the microcatheter, leaving the stent retriever in place at the level of the occlusion. Turn on the simulated aspiration to the guide catheter in the software and pull back on the microwire to retract the stent retriever device into the guide catheter. Remove the stent retriever from the simulated femoral access site and perform an angiogram through the guide catheter to ensure removal of the occlusion.

Remove the guide catheter from the simulation sheath site. In a prior study of trainees using this simulator protocol, statistically significant improvements were seen among all the participants in specific performance metrics for all three procedures, including contrast utilization, fluoroscopy time, and total procedural time. In addition, significantly increased Likert scale performance scores were observed, for which a score of one corresponded to failure and a score of five corresponded to excellence based on the procedural technique.

In addition to possessing the relevant anatomical knowledge, one of the keys to successful endovascular neurosurgery is a refined tactile sense to avoid vessel wall perforations and dissections. While the simulator includes a haptic feedback system that links complications with poor technique or use of excessive force, modulation of acceptable force during real-world training is critical for safe performance of endovascular techniques.