If I won't spend much time on the epidemiology, you've seen this, but I think this is an impressive graphic from the WHO. And basically, what you can see is, in short, over two decades, the number of people in the world has increased dramatically who have hypertension. It doesn't matter whether it's undiagnosed, diagnosed but untreated, treated but not controlled or controlled, the numbers have gone up all around the world. And certainly, there are some differences by geography that we don't have time to go into, but this is a big problem. It's a big problem in the U.S. You've seen data from NHANES as well. This is burden of hypertension, and then, of course, you've seen these data too, which speak to control, and we just don't have good control here. So this, I don't need to tell you, is a major public health issue. So who can do this? Who could perform these procedures? Well, if you take a step back and you try to be specialty agnostic, catheter-based specialists are interventional cardiologists. Some do only coronary. Some do coronary and also endovascular or maybe structural. You've got vascular interventional radiologists, and you've got some vascular surgeons, most really, who do catheter-based procedures. These are the most recent data that I could find on how many of these specialists we have in the U.S. So you'll see that interventional cardiologists number about, in the dark blue, about 4,700 or so. Vascular interventional radiologists, well, they number somewhere around 3,300, and vascular surgeons around 4,000. So it may sound like a lot of people, but for the number of people that we know who have hypertension in the U.S., no matter where we draw that line, no matter where the FDA draws that line, when this procedure is approved, we're going to have a lot of people who need procedures from probably too few people who can perform them. I can't fix that, but I think we need to start talking about that. I want to change gears to what skills an endovascular operator needs prior to performing RDN, and I will briefly touch on or mention the following. There needs to be knowledge of renal, renal vascular, and renal sympathetic nerve anatomy. The ability to interpret noninvasive studies, like duplex, ultrasound, CTA, and MRA. Facility with transfemoral and transradial access in hemostasis, because it's likely that eventually this will be a transradial technology. Expertise in peripheral vascular angiography, including both use of subtracted and unsubtracted angiography, quantitative vascular angiography, and intravascular ultrasound, which may very well lead to use of less contrast and also help facilitate device sizing. Familiarity with renal artery guiding catheter selection and engagement, and comfort, of course, with selection and use of appropriate O1 4-inch guide wires. Experience with individual devices, and those devices vary quite a bit, so that will imply experience with each of those separately. And finally, the ability to manage complications, and the good news is that there haven't been many complications in the randomized trials, but we all know the more of anything that you do, you're eventually going to encounter serious complications that may have been unavoidable, and so we need to be prepared to deal with those. On the pre-procedural imaging front, we need to be able to rule out things like polycystic kidney disease and atrophic kidney. We need to be able to rule out renal vascular anatomic disease, like FMD or atherosclerotic renal artery stenosis and erythema disease, and then, of course, we need to be able to assess vessel characteristics prior to the procedure, including the caliper and the presence of accessory renal arteries, which are there in about a third of patients. Vascular access, again, I won't spend much time on this, but you've all seen the transition from transfemoral to transradial, largely to avoid bleeding complications around PCI, but they'll largely, or likely rather, be a transition in this arena as well for a whole host of reasons, including which is that the renal arteries tend to be more down-going in origin, and so it's much easier to approach them from above than it is from below. There are aspects to doing abdominal angiography and selective renal angiography that are important for the operator to understand. The arteries don't necessarily come off in a symmetric way, and Mark Bates did an interesting study a number of years ago using MRI that showed that if you want to see the ostium, the ostia of both renal arteries simultaneously by doing an abdominal aortogram, you need to get an LAO projection, left anterior oblique projection, of about 10 to 20 degrees. That will get you there most of the time, but not all of the time. For selective renal artery angiography, most often this will be performed with five or six French diagnostic catheters, but the catheter you choose will have to be appropriate for the anatomy you encounter, and again, that's why an aortogram and or pre-procedural imaging will help you. An IMA catheter is helpful if it's an inferior takeoff. For horizontal takeoffs, a GR4 or renal double curve catheter, it's not so common to encounter a superior takeoff, but a multipurpose will help you there, as will engagement if you're coming from above. I want to emphasize, because not all specialties do this, that transduction of the distal catheter pressure I think is very important. Multiple orthogonal views of each renal artery, and really low volumes are necessary of contrast injection if you're going to be using digital subtraction angiography, which is the industry standard. Quantitative vascular angiography skills I've already mentioned are going to be necessary to select out those vessels and branches that are appropriately sized for existing devices. Currently, that's three to eight millimeters. There'll need to be some facility with alternative imaging, such as use of CO2. We talked about, you know, all these patients with CKD who haven't been in the trials, but ultimately will be performing this, I'm sure, in patients who have some risk to contrast, and so contrast-sparing technologies like CO2, use of IVUS, for example, will help us there. We'll need, during these angiographic procedures, to be able to note the size, the origin, the course, the tortuosity, and, of course, the location of bifurcations, all of which will influence how we render therapy. We'll need to be able to identify accessory renal arteries and rule out what's been exclusion criteria in prior studies, like atherosclerotic renal artery stenosis, FMD, and aneurysms. This is just a slide highlighting a number of the various shapes that are available in guide catheters for doing renal artery intervention. I've already covered most of this when I talked about diagnostic angiography, but operators will need to be familiar with these so that they select the appropriate catheters and minimize catheter manipulation. There are approaches that can be taken, and I think we don't have enough time to really get into some of the granularity here, but approaches that can be taken to minimize the amount of trauma to the abdominal aorta or the likelihood that will cause atheroembolization. The so-called no-touch technique is described or highlighted here, and the telescoping technique on this slide. Wire selection. Really, all the devices available currently use O1 4-inch wires. I don't anticipate that changing. They should have at least moderate support. Shorter transition at the tip of the wire would certainly be helpful, depending on the anatomy. Hydrophilic wires, probably not a good idea, probably associated with a greater risk of distal perforation. Perforation occurs in the ASTRL trial, which is a renal artery stent trial. It happens about 1 percent of the time, so it's not that it's a dominant occurrence, but it happens, and you need to be prepared to prevent it and prepared to respond to it if it occurs. There are three devices that are under active investigation right now. The spiral and Paradise, as you know, are closest to approval. I think we would all agree, but I think as operators, we'll need to be familiar with each of these separately. I don't think that being able to use the spiral catheter equates to being able to use the Paradise catheter or vice versa. I think they're very different, having used both. Complication management. As interventional cardiologists, obviously, we need to be ready to deal with vascular access site complications, so I'll kind of just breeze over that. But certainly, there's the possibility of aortic dissection and the need to manage that should that be caused by a catheter, of perforation of the renal artery, of dissection or thrombosis. Spasms, some operators I think will respond to, others will just leave it alone. I'm not sure it has to be treated. And then, although I haven't seen it, and frankly, I haven't heard of it yet, I'm sure it's inevitable that someone will break one of these devices and there'll be a need to retrieve it from the renal artery or elsewhere. So this is really the last thing that I want to cover, and that is just the foundational competencies for operators. Everyone wants to know, what are the right number of procedures? And I think as a group, the writing group for the SCAI document, which by the way has been posted for public comment as of this week, we struggled with this because you don't want to set the bar too low because you don't want people doing things that are going to hurt patients, but you don't want to set the bar too high because then you're basically going to restrict access for patients. People won't be able to find operators who can do this. And because most of us don't spend a lot of time in the renal artery anymore, because renal artery stenting for atherosclerotic disease isn't so common, this is a real challenge. But basically, this is what we've proposed. For those who are already proficient in renal artery intervention, we don't think any additional training in the renal arteries is necessary other than device proctoring, and we think that device proctoring should be about five cases per device. Now, if that renal artery intervention proficiency already included RDN, we don't think you need to spend another five cases on a device you already are familiar with. But if that proficiency is exclusively renal artery stenting, for example, then we think you should proctor. If you have no proficiency in this bed, then we think you likely need about 10 interventions, half of which would be primary. Again, there was a lot of debate around this. This is consistent with the recommendations that came out from multiple societies back in the 2004 document on peripheral vascular intervention. I don't think it's all that different than what the European document is saying, which is that you need proficiency. They didn't get granular about what that means, but you have to do something to be proficient. So we sort of settled on 10 for now. We'll see what happens in public comment. So in conclusion, hypertension is increasingly prevalent and poorly controlled. A subset of patients with uncontrolled hypertension will be RDN eligible. Multiple candidate endovascular specialties exist. Physician workforce issues may limit our ability to meet this demand, however. Endovascular expertise with renal artery angiography and intervention is necessary before independently performing RDN, and device proctoring will be critical given the differences in platforms currently under study. Thank you. First off, I thought that was a fantastic talk, and it's been missing in this discussion that we've had for a couple of years now, and I'm going to put you on the spot here real quick. Just thinking, outside of renal innervation trials, what percentage, what proportion of interventional cardiologists have engaged the renal artery in the last year? Just to be able to throw out a number. I have a number in my head, so I'll give you the first. For sure, it's less than 5%. If you're an interventional cardiologist in the room who's engaged the renal artery in the last year, outside of renal innervation. All right, because we have the endo guys here, and endo women. You said outside of renal, so outside of renal innervation, you've all been in the renal artery? Yeah. I would say about 5%. My guess would have been 5% to 10% of interventional cardiologists today have engaged the renal artery in the last year. So I just think it's important to remember this as we think about this therapy, is it's really a unique bed that has fallen out of favor in the last several years, and so this talk is so important. Yeah.

hypertension

catheter-based procedures

endovascular operator

renal denervation

workforce issues