Can you tell us about your practice and how you started using robotic intervention for peripheral procedures?
I am an interventional cardiologist at Riverside Methodist in Columbus, Ohio. About 80% of my practice is peripheral intervention, a majority of which is for critical limb ischemia (CLI). Patients from around the state are often referred to us from podiatrists and wound care physicians, generally for some type of ulcer. The CLI patients we see are typically elderly with diabetes, often with a history of tobacco abuse and renal dysfunction. We begin with a non-invasive workup, measuring an ankle-brachial index (ABI), and doing an assessment of blood flow and lesion location(s). The assessment may be via computed tomography angiography (CTA) with runoff to in order better define the anatomy, or depending on the exam, we may order an arterial duplex ultrasound of the affected leg, which helps us to determine the best available access points. If the patient doesn’t show any evidence of inflow problems, the vast majority of my cases are done antegrade, and approximately half will require a switch to pedal artery access or some other “extreme” access point.
A few years ago, due to our high peripheral volume, Corindus (soon to be part of Siemens Healthineers) asked Ohio Health to partner with them in order to figure out how the CorPath robotic system, which was originally designed for coronary work, would perform in peripheral interventions. I was particularly curious to see if the CorPath system could be utilized in antegrade access for the treatment of complex and chronically occluded tibial lesions. I also wanted to learn more about the robotic system’s actual hardware, its positioning in our lab, and the logistics of its use. We sought to put the CorPath system through its paces, so to speak, and determine its limits with respect to pushability and distance. In CLI/tibial work, we are using long wires, with catheters, and balloons that are over the wire and are not monorail. The CorPath system itself was designed for monorail exchange, so I knew that would be a hurdle. However, I wanted to see if the system, with its precision-guided wire movement, and to some degree, device movement, whether a stent or balloon, could be used to stay in the true lumen. Does the robot provide more pushability than we get just by using our hands? Is there some technique we could use to dig in or burrow into an occlusion more effectively than what we have traditionally done?
What have you seen so far?
I probably have 10-12 tibial cases under my belt. According to Corindus, in November 2018, we did the first tibial chronic total occlusion (CTO) with the system. Normally, I wouldn’t try to wire a chronically occluded tibial without some type of support catheter, but we have been able to get through lesions using the wire alone, just with use of the robot. Recently, I did three robotic cases, two of which were CTOs. One case involved a very long CTO that we were able to get through, and I was impressed with the ability of the drive component of the wire to keep a tight knuckle or loop on the wire when we were subintimal. We were able to do 95% of the case completely robotically, which was a first for me, because it was long chronic occlusion, about 25-30 cm. The support catheter we normally use wasn’t an option because it is over the wire, so we used a balloon as a support catheter, which doesn’t necessarily have some of the outward force we are typically used to having. We pushed the limits of the system because we were running into pushability and length issues. The system only allows for specific distance you can advance the wire and balloon/stent, presumably for the coronary arteries. You have to re-set it in order to gain the addition length required to treat tibial vessels. We are constantly learning about the robot itself and how far we can push it. We have to trick it sometimes to reset it. But, again, it is a system that in its current iteration is meant for coronaries and we are trying to take it to the next level from an endovascular standpoint. In my mind, the way forward for robotic work in the peripheral arteries will first involve antegrade access and the treatment of tibial disease. In these cases, I will do really long balloon inflations. Inflating a balloon for 5-6 minutes is tedious, but with the robotic system, it has been much nicer, because I am able to get unscrubbed and I have my lead off, sitting behind the cockpit. Our technologists and staff are awesome. However we all can get frustrated sometimes during some of these cases as there is a learning curve. I try to keep things positive, and I ask our team to imagine what it was like doing the first heart cath, or the first of anything. Yes there are growing pains, which will take time, effort, and patience to overcome. Ultimately we have a special team of nurses and technologists that are interested in helping usher this new technology into our hospital and region, and hopefully, country and world.
What is the staff interaction with the system?
We will try to have two technologists at the table, with one more senior with respect to the robot, in terms of their comfort level. Anyone who is interested, we are training. Typically I will get antegrade access via ultrasound, we will take a couple of pictures with a micropuncture sheath in, and then we decide whether it looks like a good robotics case. If it is, I will put in a sheath that is compatible for the robot. One of the technologists will help me with this, and another sets up the system cassette and gets everything teed up to proceed with the case. I will put a bend in the wire, go sit in the cockpit, the technologists will feed the wire in, and we will get to work. These lengthy cases (mainly because the balloon inflations are so long) are done through a monorail system, backing the wire out. The technologists are taking pictures — we each have a pedal to run the fluoroscopy so I let them control that — and I am in the cockpit, driving the wire and the balloons. It has become a harmonious and synergistic process.
Can you describe the robotic system’s cockpit?
In our lab, it is located five feet away from the head of the table, closest to the door through which the patient enters. It has joysticks, screens, and leaded glass. When I sit there, the team jokes that I should have a cup of coffee. It’s curious. I don’t know if a year ago I would have thought I would be completely unscrubbed while doing a case. Sometimes I’ll run and get equipment out of our equipment room while the technologists are making balloon exchanges. Again, many of our technologists are interested in learning more about the device and we are teaching them how to use the system. Hopefully, in the future, the CorPath can be used for a tele-procedures, possibly in areas without a physician. In service of that goal, technologists can be trained to understand the machine and how to do some of the injections, and if somebody can get access, these cases could potentially be done remotely. It might be that a physician’s assistant or a physician who doesn’t do intervention would get access, and then the interventionalist would work from a remote location while using the CorPath robotic system.
What about time?
The cases are longer, because we are trying to outfit a device that is made specifically for coronary work and so peripheral procedures are the square peg in a round hole. Our technologists are learning the flow and how to be more adept at rapid exchange. Every once in a while we run into a hiccup, but we have representation from the company that helps support us while we trouble shoot things. There were initial learning curves, specifically around putting a sheath in, as we figured out quickly that the standard sheath we use wasn’t compatible with the device, relatively simple things like that. Definitely, however, cases are getting quicker. We did two in one day last Friday. We first started in November 2018 and over the past several months, have made a lot of improvements. While the ability to be “lead free” is attractive, the selling point, in my mind, is being able to work with a device that allows for very precise and calculated movements that eventually will reduce the time it takes to do some of our procedures. I know the company is coming out with a new cassette and new software that allows the wires to move in different ways. The ability to stay in true lumen from an antegrade approach, thus maintaining a single arterial access point (avoiding retrograde access), is where I see real advantages with this system. Moving forward, we hope to partner with other companies to develop support catheters that could be made compatible with the robot. The opportunity to have this type of input was a selling point for us, because we are using the device and understand what it can and can’t do, and what is needed. As an example, the GuideLiner (Teleflex) is a monorail system where a guide is advanced into a coronary artery when more support is necessary. We need a similar monorail support catheter that can be used in the peripheral arteries, with more of a tapered tip to allow us to dig into these vessels as we are trying to wire in. Currently there are no monorail support catheters out there for peripheral use. For now, we have been using a balloon and have to “MacGyver” equipment as needed.
You mentioned using duplex ultrasound and CTA with runoff. Do you anticipate any changes to these technologies or other imaging modalities that might help in use of the robotic system specifically?
Today’s imaging technology offers us the ability to provide three-dimensional layouts of the vessels. Future developments might permit the robotic system to drive the wire autonomously if the vessel is mapped out first. I use CTA and duplex ultrasound for making the diagnosis and evaluating the anatomy ahead of the procedure, perhaps there could be a synergy between some type of 3D vessel reconstruction and using the precision-guided wire and device movements of the robot to understand your location within the vessel.
What has been the impact of not having to wear lead during robotic cases?
There are anecdotal reports of interventionalists suffering left-sided brain tumors, and while I don’t know that the relationship is causal, perhaps there is a signal, and that is a concern. If you can get away from wearing lead and standing in radiation, that is a good thing. The other issue is that the technologists are exposed, so we are working on getting them farther away as well, using appropriate shielding and extension tubes for the injection. I would hope that in the future we live in a cath world that is devoid of exposure radiation exposure. Consider also the 25% of interventionalists suffer from some kind of orthopedic issue while wearing lead, and frankly, I don’t want to wear lead for another 20 years. It takes its toll over time. As a society, as physicians, and for those who manage cath labs, we need to look at ways to reduce radiation exposure not only for physicians, but our staff. Being able to do so with use of the CorPath system was a big selling point for us, something that Ohio Health recognized and saw as a need. They purchased the robot in part as a commitment to reducing injuries and radiation exposure.
It sounds like Ohio Health is supportive of the robotic system.
Very much so. When you are signing the check, you want to vet the equipment and do due diligence. It was an extensive process. We had the appropriate administrative and physician support, and when all was said and done, people liked the idea. Not only from a radiation safety standpoint, but they liked the idea of being the first in central Ohio to have the robotic system. That in itself demonstrates the mindset of Ohio Health — progressive, innovative, and cutting-edge.
Is the CorPath system being used for coronary procedures at Ohio Health?
Yes, but we have done more peripheral procedures with the system than coronary procedures.
Any final thoughts?
Other media outlets will frequently ask us how the robotic system benefits the patient. In all honesty, at this point I can’t say that it specifically benefits my patient; however, it is my hope that the more we use the robotic system in our peripheral cases, the more we can reduce procedure times, patient, operator, and staff radiation exposure, use of alternative access sites, and finally, complications. The goals here are simple: get the procedure done more efficiently in a safer environment with less radiation exposure for all, so the patient can heal, and to preserve their limb. We are not there yet, but will be someday.
Disclosure: Dr. Phillips reports no conflicts of interest regarding the content herein.
Dr. John Phillips can be contacted a firstname.lastname@example.org.