All right, thank you. Next speaker is Dr. Shah, talking to us in, again, a late-breaking abstract about transradial approach to complex anterior and posterior circulation interventions, technical nuances, and feasibility using current devices. Good afternoon, ladies and gentlemen. My name is Sumedh. I'm one of the third-year medical students. Not a doctor yet, but working on it. This presentation represents our journey in converting a significant number of our endovascular procedures to transradial access. By its completion, this talk hopes to provide a sense of how safe and feasible transradial access can be for neurointervention, as well as offer some technical nuances that we learned along the way. So before we begin, here are my fellow co-authors and mentors, as well as our pertinent disclosures. So access is often an afterthought, but when discussed, many operators tend to come to this conclusion, that complications from femoral access are rare. However, they're not as infrequent as we'd like to believe. When we look at our prospective literature, it becomes quite clear that these complications occur in up to 11% of our interventions. These serious events include things like growing hematoma requiring transfusion, dissection, occlusion, pseudoaneurysm formation. Furthermore, there is a known mortality risk from access alone. Now, the risk from femoral access may surprise some in endovascular neurosurgery. However, our colleagues in cardiology have known about and studied this risk for decades. Neurointervention has a long history of lagging behind interventional cardiology innovations by five to 10 years. One of these biggest innovations in cardiology has been the shift away from the femoral artery towards the radial artery as an access point for its interventions. This transition has been largely driven by dozens of prospective randomized trials looking at the impressive safety benefit of radial versus femoral access. And recently, the largest of these trials actually showed a mortality benefit as well. Based on this data, the European side of cardiology actually formally recommends in a guideline produced in 2013, radial artery access is first line for all cardiac interventions in Europe. And this impressive safety data has also driven conversion across the world towards radial access, particularly in Europe, Asia, and Latin America. But is this cardiology journey really applicable to neurointervention? Well, even though the end target is quite different, the access is identical. The safety argument for radial versus femoral access in neurointervention is significant since most of these procedures are done using large bore catheters and most patients are systemically heparinized and on dual ENT platelet therapy. Thus then, the question is not of safety, but of feasibility. In the first step to address this question, we recently converted our lab to a radial first for diagnostic angiography. This 12-month experience was recently published in JNIS where we were able to successfully perform 148 cerebral angiographies without complications and high success rate. Most importantly, we identified efficient ways to select our target vessels. So here, our procedure has been described at length, but I will mention that catheterizing the left or right common is generally straightforward and we use a Simmons 2 catheter. In many cases, we can access the right carotid without having to venture into the arch. And in cases of left CCA, we can access it in bovine arch variants. When we do need to enter the arch, we identified common really good ways to reform the Simmons 2 catheter. What we tend to do is use the descending aorta where we park the diagnostic catheter over guide wire into the ascending aorta, retract the guide wire, advance the diagnostic system forward. This causes the Simmons 2 shape to naturally form as you can see in C from D. Based on this favorable experience, we began transitioning the majority of our interventional practice towards the radial artery, particularly anterior circulation interventions which historically were thought to be difficult from this approach. In two years, we identified 105 cases. More than three quarters of these were anterior circulation and more than half of these were left side interventions. Crossover was roughly 9%. We had zero serious access site complications, one radial artery occlusion which was asymptomatic, and two radial artery spasms. Of note, no permanent neurological complications were identified. Here we see the breakdown of procedures performed. Roughly a third constitute mechanical thrombectomy, a third constitute aneurysm treatment, and a third constitute embolization and miscellaneous treatments. And it's important to note that almost half our cohort actually came from procedures where it's generally required to have more stable catheter constructs, particularly thrombectomy and flow diversion. Regardless of the system used, the access technique is very similar and depicted here. We illustrate the left side that tends to be more challenging. Basically, you catheterize the left common carotid with a guide wire and diagnostic, and in a manner identical to ephemeral SIMS 2 catheterization, you coaxially place the interventional system into the ICA. I have a short video here that describes this. What I'm going to show you here is just for your orientation, we've already placed the SIMS 2 in the arch, and the guide catheter, excuse me, is in the innominate. In a contrast puffing technique, we're going to isolate the left common, and at this point it's important to maintain apposition of this catheter structure against this inner vessel wall in order to prevent herniation. The road map is then done. In this part of the video, the guide wire is brought into the ICA, and you'll see a lateral plane as well. You can see that the guide catheter is being brought into the left common over the diagnostic and guide, and a guide wire. Here, in the lateral plane, the wire is brought into the left ICA, followed by the diagnostic, and then a guide catheter in a coaxial manner, as you can see here. It's important to note that once the guide catheter is in place, the procedure would go as forward as in any other femoral intervention. So in terms of crossover, we had 10 patients that required crossover to femoral access, and this table displays their characteristics. We start to note that certain anatomical configurations made selecting target vessels more difficult. Particularly, proximal left common tortuosity, as shown in red, prevents the apposition of the Simmons 2 catheter against that inner vessel wall, and this causes herniation of the system into the arch. Additionally, proximal origin and tortuosity of the vertebral arteries causes similar difficulty in access. A little bit about radial artery occlusion. As we've discussed at length in our previous publications, radial artery occlusion is a minor issue, considering that most of the time it's asymptomatic. We did see one case of radial artery occlusion, and that was after a guide catheter was introduced without a sheet into the radial artery, 0.088 in diameter. This was asymptomatic with no hand ischemia. We prefer to use the same artery for repeat interventions, so we make every effort we can to minimize the occlusion rates. The prospective cardiac literature has shown that this occlusion rate can be kept under 5% if optimal access techniques are used. Pictorially shown here is the patent hemostasis technique for after the procedure. In terms of some technical nuances, most of our cases were done using a six French sheath and guide. We prefer to place the guide catheter over a longer diagnostic catheter, as opposed to doing catheter exchange. We have an institutional bias against that. In terms of the difficult cases we did, in terms of mechanical thrombectomy and flow diversion, we found that for flow diversion, the seven French balloon guide catheter and sheath were optimal, but sometimes we were able to go as far as going up to an 0.088 catheter without a sheath. We had good rebascularization, but we're going to need more patients to formally examine this. In terms of flow diversion, we did most of our case with a six French sheath and 0.071 catheter, plus a standard 0.058 intermediate. We did experiment with smaller intermediate catheters, but found that these tend to provide less support, particularly given that substantial forward loads during the flow diversion cases can lead to the system herniating into the arch. In terms of the sheath versus sheathless weight, we tend to also measure the radial artery diameter before the procedure, and this guides the sheath and guide catheter selection. In terms of limitations, the limitations of the radial artery approach truly come from the fact that there are no radial-specific systems for neurointervention. Cardiology has that advantage that some of their systems are designed for radial access, but unfortunately, better tools are going to be needed for neurointervention. That being said, we were able to successfully complete these procedures using the current femoral systems. And we did already go over the anatomic challenges discovered, so in the interest of time, let's go over those. So ultimately, this series represents the largest-to-date neurointervention completed via transradial access. It is safe, it's feasible, and particularly in patients who are obese and patients who are on anticoagulation or dual-antitheliotherapy. Pardon me. The limitations can be overcome with operator experience as well as systems improvement. And finally, our future directions include matched cohort comparisons and ultimately advocating for radial-specific interventional systems. Thank you very much. We can take one question while our next speaker comes up. So we do. So in terms of our pre-procedural technique, we do a Barbeau test. And so in terms of a patient, Barbeau D, and our patients are the ones we don't tend to like to do radial artery access to. I know that there are some cardiac literature that suggests that the artery occlusion rates can be decreased if you do ulnar artery compression after the procedure. But for the most part, we're pretty comfortable using the radial artery in specific. So most of the time, we don't need to check the ulnar artery patency. But in our case, the one radial artery occlusion was no hand ischemia was seen. So it's a complication, yes, artery occlusion, but for the most part. The Barbeau test, we think, is pretty sufficient.

transradial approach

neurointervention

safety and feasibility

radial versus femoral access

access technique