Frank Maddux: Improving vascular access care is key to improving outcomes for people receiving hemodialysis. In this edition of Global Medical Office Dialogues, our guest is Dr. Walead Latif, an interventional nephrologist and vascular access care expert. Medical director at Azura Vascular Care in the United States, Dr. Latif weighs in on improving patient outcomes by addressing challenges and opportunities in vascular access. Welcome, Walead, to Dialogues.
Walead Latif: Thanks Frank for having me.
Frank Maddux: Let's start by talking just a little bit about what you think the impact of COVID-19 has been and the pandemic on vascular access care, both in the U.S. and also abroad.
Walead Latif: What we found was that both in U.S. and globally that the immediate impact of COVID-19 as it started to unfold as a pandemic was to temporarily increase the incidence of catheter use for new start dialysis patients and what we've found is that relative to historical trends that the incident use of catheters both in U.S. and globally had a slight uptick at the height of the pandemic in mid- to late-2020. Furthermore, in the U.S., we also found that there was a shortage of operating room space because hospitals were inundated with taking care of COVID patients so on a temporary basis, particularly early on in the pandemic, there was a moratorium on use of operating rooms because they were reserved for folks that really needed to be on ventilators and such. One of the things that I thought was a positive that came out of this was that the dialysis access community was able to lobby CMS and other regulators to essentially tell hospital administrators that vascular access surgery was indeed a vital surgery and that it should not be necessarily delayed during the peak of the pandemic. Having said that, there were still some delays in getting vascular access placement in our patients.
Frank Maddux: What do you think the impact was in the vascular procedures like the ones that you do in Azura, did you see a decrease or was that maintained during the time of the pandemic?
Walead Latif: There was definitely a decrease in the number of maintenance procedures that were performed on dialysis patients and the reasons for that were severalfold. One, I think a significant number of patients were too scared to actually go anywhere else other than getting their life-saving dialysis treatments, and second, we as an organization sort of made the decision, at least for a short period of time, that in order to reduce exposure to our patients that we really wanted to only perform those procedures that were absolutely vital so thrombectomy procedures, catheter changes and patients that we have a long-standing relationship with that we know that a preventative angioplasty really will prevent a future thrombotic event and therefore not allowing them to achieve continuous dialysis.
Frank Maddux: Let's shift gears for a second and talk about some of the newer vascular access creation methods that I know you've had some experience and exposure to. Both the Ellipsys device and the WavelinQ device have now come onto the scene and are providing a way to create a percutaneous AV fistula, do you want to describe these a little bit and just tell us your thoughts about the role they may play?
Walead Latif: I find that the advent of percutaneous fistula has really been a game changer for vascular access care. The two devices are slightly different in the way that they deliver the percutaneous approach. The Ellipsys device by Avenu Medical really uses ultrasound guidance only and with ultrasound guidance you're able to fuse an artery and a vein together and this creates an upper arm fistula and they've now started exploring a forearm fistula using the same sort of technique. The WavelinQ device by Bard uses fluoroscopy and what you're doing is you're puncturing both the brachial artery and the brachial vein and there are magnets that need to be aligned on the fluoroscopy and once they're properly aligned through fusion, you're able to create the anastomosis and therefore you get a fistula in that way. Both devices I think work well and I do find that this really has been at least in the last 40 years perhaps the single biggest gamechanger in the way we're able to deliver vascular access to our patients.
Frank Maddux: And have you felt that patients have responded to this? Do you get people asking about it or do they consider it a surgery or do they consider it just another procedure? I'm just curious how the patients have responded.
Walead Latif: I have found that patients, when they get word of it, are asking quite a bit about this new technique and whether they can qualify for it. I would say that most of them do demonstrate some level of excitement about the prospect of getting a percutaneous fistula because it's a same day procedure. It doesn't require general anesthesia. It could be done in a hospital outpatient setting or an ambulatory surgery center setting and it leaves them with no surgical scars which I think from a patient's perspective is advantageous.
Frank Maddux: How about maturation times and the need for some assisted maturation in these types of fistulas, is it any different than the usual AV fistula?
Walead Latif: When you review the literature, they don't really track that and it doesn't really discuss whether there are more maturation interventions that are required. Anecdotally from folks that have performed these procedures, and from my own personal experience, I do find that they will require a little bit more maturation than perhaps an open surgical technique from a historical perspective. It's a little tough to sort of compare the percutaneous approach to the open surgical approach because there are significant confounding variables: Vein selection, operator technique, so all these sort of weigh in as to whether a patient would require a maturation procedure or not, but generally speaking I think they do require maybe a slight more in terms of maturation procedures than the traditional techniques.
Frank Maddux: The other thing that I know we've talked about before is the depth of the vessels sometimes is relatively deep and are there any issues related to initial canulation or consistent canulation of a fistula that's prepared from these deep vessels?
Walead Latif: Yes, so that's a great question. I would say that what we don't realize are that dialysis nurses and technicians really use the surgical scar as a visual landmark as to where I should canulate my patient. With these techniques, there's no surgical scar so it's not infrequent that until there's a learning curve with the dialysis clinic, they sort of don't know where to begin to canulate the patient. Now, in terms of depth of vessels, I would say that the Ellipsys device by Avenu is less likely to have that issue because the approach is through more of superficial veins and perforator veins. With the WavelinQ device, the fusion of the deep ulnar artery with the deep ulnar vein is supposed to help mature more superficial veins. Sometimes that happens, sometimes it doesn't, but when it does happen, it's successful. When it doesn't, then quite frequently you may need a second procedure to help superficialize a deeper vein.
Frank Maddux: Any other advantages or disadvantages to this method? And then we can talk about some other innovations that are coming down the pike.
Walead Latif: Well, I think that the greatest advantage to it is the speed with which you can get patients into get their fistula. There's no need for cardiac clearance. There's no need to wait for OR times. It's done under local anesthesia with maybe some conscious sedation so from that perspective we really are able to improve on our catheter exposure time because we can get fistulas created in patients much more quickly. I would say that the minor disadvantages would be one, the need to educate the dialysis clinic where they can canulate patients because again that visual sort of reminder about where the scar is isn't there and second, I think it's important that when interventionalists are screening their patients to perform a percutaneous fistula that they are cognizant of the fact that most of these fistulas are more proximal, meaning above the elbow, and if someone has a very readily useable Cimino fistula that is created by the traditional open technique that that should still be preferred before you proceed more proximally.
Frank Maddux: We've talked previously about some of the other innovations in the field, one of which is the Human Acellular Vessel that HUMACYTE is developing. I'm curious your perspectives on the HAV and maybe just describe it and then talk a little bit about what you think its advantages or disadvantages might be.
Walead Latif: It's really an exciting time to be in this space and HAV really is quite the gamechanger. What it is, it's a human acellular vessel you get a human acellular device or something that would approximate a native fistula. What's exciting about it is that you literally could take something off the shelf if you will, size it appropriately for the patient, and implant the device and because it has no immunogenetic factors and it's endothelialized by your own native cells that the infection rates essentially approximate an AV fistula, which is very different than a traditional PTFE AV graft, so from that perspective I think the fact that it can be customized and that it can be readily implantable with very little infection possibilities gives it a huge advantage over anything else that's come along in the last 30 years.
Frank Maddux: Clearly, in their early trials, their infection rates and risk was much lower than either PTFE or other methods. I think the other part which was pretty interesting was the fact that percent-reactive antibodies and other things in helping people get prepared for a transplant were not elevated when exposed to the HAV. So, it's an interesting part of the field. What are some of the other techniques and things happening in your endovascular work today that you all are doing, any other new or novel techniques that you're seeing utilized?
Walead Latif: HAV I think is still coming and I think that's going to continue to proliferate. When it comes to other things that I think we're starting to see, there's a new device that still hasn't hit the market yet which essentially acts like a blood pressure cuff and you're able to apply it to a patient either post-intervention or post-dialysis and you inflate it like a blood pressure cuff to about 20 or 30 mmHg and 15, 20 minutes later you remove the cuff and there's really no more bleeding and this needs to be more rigorously studied but what's exciting about it is that I think it will reduce pseudoaneurysms and some of the ulcerations and skin breakdown that occurs from either sutures that we place as an interventionalist post-procedure or some of the clamps and injurious gauze that dialysis clinics apply.
Frank Maddux: I know several years ago you began doing some peritoneal-related procedures and placement of PD catheters, do you find most interventional nephrologists are beginning to adopt a sort of modality agnostic role that they have in providing access to that therapy?
Walead Latif: Yes, I've seen a significant uptick over the last five years in folks that are more comfortable providing fluoroscopic approaches to placing peritoneal dialysis catheters and I think that's consistent with the government mandate and the dialysis communities sort of push to get more home therapies and PD is certainly at the forefront of that.
Frank Maddux: One of the things that is clear to me is that our patients have this sort of rampant cardiovascular disease and vasculopathy that's going on, do you see anything changing in the morphology of the patients that you're taking care of with diabetes and others that their vessels are either in better shape or worse shape or what's been sort of over the course of your career some of the changes that you've seen in the types of problems, the types of patients that you're seeing?
Walead Latif: I would say that particularly recently, as there have been more patients that have transitioned to home therapy, I find that the cardiovascular morbidity has really improved. Folks, which we know is the case, will tell me that I feel better. I'm taking less blood pressure medicines. I don't find that they are getting hospitalized for volume overload or other cardiovascular related issues, and so I think that is a significant change in the way we are able to take care of patients from a cardiovascular perspective. The second thing that I think has really come to light which was much more prevalent earlier on is this concept of high output cardiac failure in patients with more proximal AV fistulas. I would say that when I started my career, that wasn't something that was really discussed but we've had more of an emphasis on looking at that as a potential adverse event for patients. Certainly some of the techniques that have come out to restrict the AV fistula flow I think has really done a lot to improve the patients' cardiovascular outcomes, kind of reverse some of the left ventricular hypertrophy that we know can happen, and I think that really has done a lot to improve patients' lives.
Frank Maddux: How about peripheral limb ischemia with regard to Steel Syndrome and so forth, is that still a sort of relevant comorbidity that you see in the patients we treat?
Walead Latif: I would say unfortunately we still see quite a bit of peripheral artery disease and limb ischemia and toe and below-knee and above-knee amputations. I think that our patients need to be studied because they are a unique subset of folks that as we know traditionally the CKD patient of the general population of patients, some of the trials and some of the outcomes and data that have come from that really don't apply to the dialysis patient. Nonetheless, these patients still suffer from peripheral arterial disease and rather frequently they are excluded from trials and I think moving forward we really could begin to hone in on how do we take care of a dialysis patient's peripheral arterial disease through either pharmacological approaches or endovascular approaches.
Frank Maddux: Any final comments, Walead, on what you see happening in the vascular access arena these days?
Walead Latif: I think if I could just look into a crystal ball for a second, I think we're going to see much more emphasis on wearable devices for patients, both generally and within the dialysis patient population. I think in the not so distant future, we're going to have wearables where we can have monitoring and surveillance that occurs on a 24 hour, 7 day a week basis, where a patient can wear something and we can then through an app upload it and be able to identify access dysfunction, again preemptively without having to wait for some of the clinical signs that we have traditionally been trained to look for.
Frank Maddux: Have you seen any of the wearable devices like the BioIntelliSense device or others like that that you've recognized have a component of sensing related to the vascular access either through sound or through assessment of a thrill or something like that?
Walead Latif: There is a device that Renal Research Institute has done quite a bit of research on and through the use of a camera, the app is trained to sense changes in the thrill and the vibration of the fistula and based on that, it is able to detect an underlying stenosis so again I think this is just the first iteration of what I think will become much more prevalent wearables for folks to detect underlying vascular access dysfunction.
Frank Maddux: I appreciate the time today, Walead, thank you very much. Dr. Latif is based in the New Jersey area and is one of our medical directors for Azura and we greatly appreciate you participating on Dialogues today.
Walead Latif: Thanks for having me, Frank. I really appreciate the time spent with you.