Selected Podcast
Physician Modified Endovascular Graft (PMEG) for Treatment of Aortic Aneurysms
Zain Shahid M.D., defines physician modified endovascular grafts (PMEG). He describes patient selection and the indications for PMEG and he helps us to understand the role of PMEG in treatment of complex aortic aneurysms.
Featuring:
He received his Bachelor of Medicine and Bachelor of Surgery at the Aga Khan University in Karachi, Pakistan. He graduated with honors and was awarded a merit scholarship for being among the top 15% in his class.
He started his general surgery residency at Johns Hopkins Hospital in Baltimore. He then moved to University of Texas, Southwestern Medical Center where he completed his residency and also served as the chief resident. Subsequently, he completed a vascular surgery fellowship at the University of Florida College of Medicine.
Dr. Shahid’s clinical interests include treatment of complex aortic aneurysms and dissections using fenestrated endografts. In addition, he treats patients with renal and mesenteric occlusive disease, cerebrovascular occlusive disease, peripheral vascular disease and hemodialysis access.
Dr. Shahid is board certified in general surgery through the American Board of Surgery. His peer-reviewed articles and oral presentations have specific interests in aortic dissection, appendicitis and surgical residency programs.
Zain Shahid, MD
Zain Shahid, M.D., is an assistant professor in the division of vascular surgery and endovascular therapy at the University of Florida College of Medicine.He received his Bachelor of Medicine and Bachelor of Surgery at the Aga Khan University in Karachi, Pakistan. He graduated with honors and was awarded a merit scholarship for being among the top 15% in his class.
He started his general surgery residency at Johns Hopkins Hospital in Baltimore. He then moved to University of Texas, Southwestern Medical Center where he completed his residency and also served as the chief resident. Subsequently, he completed a vascular surgery fellowship at the University of Florida College of Medicine.
Dr. Shahid’s clinical interests include treatment of complex aortic aneurysms and dissections using fenestrated endografts. In addition, he treats patients with renal and mesenteric occlusive disease, cerebrovascular occlusive disease, peripheral vascular disease and hemodialysis access.
Dr. Shahid is board certified in general surgery through the American Board of Surgery. His peer-reviewed articles and oral presentations have specific interests in aortic dissection, appendicitis and surgical residency programs.
Transcription:
Scott Preroll: The University of Florida College of Medicine is accredited by the Accreditation Council for Continuing Medical Education, ACCME, to provide continuing medical education for physicians. The University of Florida College of medicine designates this enduring material for a maximum of 0.25 AMA PRA Category 1 credit. Physicians should claim only the credit commensurate with the extent of their participation in this activity.
Melanie Cole, MS (Host): Welcome to UF Health MedEd Cast with UF Health Shands Hospital. I'm Melanie Cole. And today, we're discussing physician-modified endovascular grafts for treatment of aortic aneurysm. Joining me is Dr. Zain Shahid. He's an Assistant Professor in the Division of Vascular Surgery and Endovascular Therapy at the University of Florida College of Medicine, and he practices at UF Health Shands Hospital. Dr. Shahid, I'm so glad to have you with us today. I found this fascinating research. I'm really glad we're doing this topic and I've been looking forward to this podcast. Can you start with a little bit of the evolution of endovascular repair of aortic pathology in patients with aortic aneurysm? Why has this shown to be a bit prohibitive? Why the need for improved device design?
Dr. Zain Shahid: Yeah. Thank you, Melanie, for having me. So, overall, generally open repair has been the gold standard for a pair of abdominal and thoracoabdominal aortic aneurysms. Over the past three decades or so, however, there has been refinement of EVAR technology. And now that's available and there've been various commercial endograft systems that are now available. Many of those are now in their third or fourth generation. That has led to a transition of clinical practice from open surgical repair to EVAR in the elective management of abdominal aortic aneurysms and in some cases, thoracoabdominal aortic aneurysms. Currently, in the US actually, EVAR far exceeds open repair, especially out in the community.
Over time as this transition has happened, we have seen patients who've had endovascular repair done 10 to 15 years ago now starting having problems. That can mean they've had migration of their endografts, they've developed endoleaks, they're developed infections or other issues, that have required secondary interventions, either more complex endovascular repairs or open repairs.
Melanie Cole, MS (Host): Well, thank you for that explanation. So as more and more patients who would be deemed unsuitable candidates may be based on anatomic criteria, I'd like you to tell us now about physician-modified endovascular grafts. What are they and what does that mean when you say physician-modified? Does it mean custom design has been promoted with each device? Custom made for a specific patient? Please explain that to other providers.
Dr. Zain Shahid: Yeah. So physician-modified endovascular grafts is a term that's used to describe physician modifications or modifications that I make to commercially available abdominal and thoracic endograft. So that means creation of fenestrations or holes, direction branches. or scallops. It sort of depends on the patient's anatomy and what we are treating. So these devices are specifically made for each patient or modified for each specific patient. No two devices are the same and there are certain sort of ways how you modify those. And there are certain indications for this, which we'll discuss in a bit.
Melanie Cole, MS (Host): So I'd like to get right into that. And then tell us about the role of PMEG in the treatment of complex aortic aneurysms. Tell us about those clinical indications and patients selection.
Dr. Zain Shahid: Right. It is indicated for patients with complex abdominal aortic aneurysms, which includes juxtarenal aneurysms, pararenal and suprarenal aneurysms. It's also indicated for patients with a thoracoabdominal aortic aneurysms types 1 to 5, depending on what the patient has. They're also indicated in patients who have had chronic dissections with now aneurysmal dilatation and something that we see more and more commonly, it's also indicated in patients who have had failed prior endovascular aortic repairs, or EVARs or open repairs. These patients are generally not candidates for open repair. They're not candidates for commercially available fenestrated endografts, and they cannot be enrolled in industry-sponsored clinical trials for the new and upcoming endografts.
We do have a pretty strict inclusion and exclusion criteria. So I told you a little bit about what the indications are as far as, and obviously those patients are included in the study. But in addition to that, patients need to be 18 years of age or older and be able to sign consent for the procedure. There are very specific anatomical criteria that are also important. There needs to be a good proximal landing zone in the aorta of appropriate size. We also need an appropriate distal landing zone, either in the aorta or the iliac vessels of appropriate size. And then we need to have our target vessels, which are generally the visceral vessels in which include the superior mesenteric artery, celiac artery and the renal arteries to be of certain size to be able to put stents in.
In addition, the overall health of the patients is important. We do these procedures in hopes that we prolong their life and their aortic-related morbidity and mortality is decreased. So we do want to see that the predicted one-year rupture risk of the aneurysm is higher than the one-year mortality after repair, so in case we're doing a complicated operation, which will eventually prolong their life.
Melanie Cole, MS (Host): As far as challenges, Dr. Shahid, one might imagine that any device customization involves a time delay between patient sizing, manufacturer of the device, the implantation event itself. Tell us a little bit about how long currently the process takes in the best of circumstances and how you have found to be the case. How have you addressed this challenge?
Dr. Zain Shahid: Yeah. So that's a good question. So these modifications are made onsite at UF Health Shands Hospital, that is we make those modifications ourselves. So the grafts that are provided by the company are commercially available. We have them on stock. So there's no as such delay for a new graft to be made for the patient. We make the modifications the day of the operation.. So, for example, if a person comes in to clinic today and wants this operation, and he has a very large aneurysm and we think it needs to happen within a week or so, we can fit them in the schedule as soon as tomorrow. Generally, no one needs that kind of thing, but maybe even next week. And then what we do is every patient gets a CT. So we upload the CT scan in our special central line software. And then we take precise measurements to the nearest millimeter as to where the important branches, which I mentioned, which are generally the celiac, the SMA and the renals come off. And then you modify the graft the day of the operation based on those measurements. It takes me approximately one to two hours to make the modifications to the graft. And i usually start making the modifications before the patient is brought back into the operating room. And by the time the patient comes in, is intubated and has the appropriate lines placed by the anesthesia team, the graft is ready and we're ready to start the case.
Melanie Cole, MS (Host): Wow. That's absolutely fascinating. Now, I'd like to address the elephant in the room, Dr. Shahid, for other providers, does there exist a legal risk to modifying an existing FDA-approved medical device? Does this involve product liability? Can you speak to other providers about this portion of this?
Dr. Zain Shahid: Yeah. That's a good question. So this is considered an off-label repair, no doubt about that. And I am very clear to my patients and our consents are very clear about that. Again, we are only offering this to patients who are not candidates for an open operation, not candidates for sort of commercially available endovascular grafts, fenestrated endovascular grafts, and can not be enrolled in clinical trials. And these patients understand that. And we get special refferals with the understanding that that's what they will be getting.
Now, we have sort of collected some data over the last couple of years, which we are planning to submit to the FDA to try to obtain an investigational device exemption. So we can do these procedures under the umbrella of a clinical trial. I think that will expand our indications and allow us to treat more patients as well.
Melanie Cole, MS (Host): Is there a difficult learning curve to what you're doing? You said it takes you a couple of hours to modify the device. Are there technical considerations you'd like to share with other providers to help them achieve better outcomes should they head into this?
Dr. Zain Shahid: So, yes, I think there is a steep learning curve for this. These procedures are generally done at sort of large academic centers, because it's not just me, it's a whole team to be honest. So you need to have good anesthesia staff. You need to have good nurses. You need to have good. Surgical techs, good IR techs and A good ICU team to sort of understand what we're doing. The modification, like you said, takes one to two hours. And I think over time I've sort of become faster in doing these. I think initially, when I was in training, when I was doing these, it took me three hours or longer to modify a graft.
Really the most important thing about modification is your planning. So when you do your measurements on your CT scan, they need to be really accurate. And generally, what we do here at UF Health Shands Hospital is I make my own measurements, and there's a second person and sometimes a third person who does their own measurements. And then we compare. And this is to the nearest millimeter to make sure that our measurements are accurate. And then we make those modifications and there are multiple ways to make modifications. I mean, people do it a little differently, but what we've seen and we've had good results with is just reinforcing our fenestrations with the PTFE or Teflon and we put special coils around them that allows us to see them really well on the fluoroscopy. So I think I think it's not easy for people everywhere in the community to do these cases because of the support needed and the complexity of imaging required. So for those reasons, most of these patients are referred to pick a tertiary or quaternary care centers, and there very few of those that are actually doing these operations.
Melanie Cole, MS (Host): That's a great point that you made. And I'd like you to reiterate that as we wrap up. I'd like you to first tell us how your outcomes have been and where do you see this going in the future? Do you have final thoughts for physciains as far as immediate device modification and how it really, as you just said, should be performed at centers completely familiar with all advanced endovascular, aortic and visceral artery techniques and a high volume of these fenestrated procedures.
Dr. Zain Shahid: Right. Yep. So the outcomes, so our outcomes over the last two years have been excellent. We've had no deaths in the first 30 days, which is amazing. Our target vessel cannulation, which are our SMEs, celiac and the renals has been close to a hundred percent. Spinal cord ischemia, which is a major risk with complex aneurysms, specifically large thoracoabdominal aortic aneurysms has been less than 3% to 5% in our series. Secondary reintervention rate for endoleaks or aneurysms proximally or distally has been less than 5% to 7%. In addition, the incidents of major cardiac events, renal dysfunction, stroke, et cetera, and other in-hospital complications have been low. But of course, I think this all seems very rosy, but I think as we continue to do more cases and gather more long-term data, I think these numbers are bound to change.
And then as far as sort of closing statements, I think this is a really complex operation. I think straightforward endovascular repairs, infrarenal repairs, absolutely can be done anywhere in the community, people who have basic understanding of aortic pathology. This requires team effort. This requires a lot of complex sort of planning, equipment and it requires a lot of knowledge in how to, A, do the operation and what to do if the operation doesn't go well, I mean, it's bound to happen at some point where you're in a spot where you're not sure what to do next. You need sort of your partners that have an understanding of how to deal with those issues. And you need to have experienced with those issues. And that can only be done in places who do a high volume of these cases. I think if you're doing one or two of these a year, I think the outcomes are bound to be not that good, like with any other sort of complex operation. We've now been doing one or two a week. So as you can imagine, we've had those complex issues, we've dealt with those and we thankfully have really good outcomes.
Melanie Cole, MS (Host): What an interesting interview this was. Thank you so much, Dr. Shahid for joining us today and sharing this incredible information and this incredible technique that you're using at UF Health Shands Hospital. To refer your patient for physician-modified endovascular graft for treatment of aortic aneurysms or to listen to more podcasts from our experts, you can visit ufhealth.org/medmatters.
That concludes today's episode of UF Health MedEd Cast with UF Health Shands Hospital. For updates on the latest medical advancements, breakthroughs and research, follow us on your social channels. I'm Melanie Cole.
Scott Preroll: The University of Florida College of Medicine is accredited by the Accreditation Council for Continuing Medical Education, ACCME, to provide continuing medical education for physicians. The University of Florida College of medicine designates this enduring material for a maximum of 0.25 AMA PRA Category 1 credit. Physicians should claim only the credit commensurate with the extent of their participation in this activity.
Melanie Cole, MS (Host): Welcome to UF Health MedEd Cast with UF Health Shands Hospital. I'm Melanie Cole. And today, we're discussing physician-modified endovascular grafts for treatment of aortic aneurysm. Joining me is Dr. Zain Shahid. He's an Assistant Professor in the Division of Vascular Surgery and Endovascular Therapy at the University of Florida College of Medicine, and he practices at UF Health Shands Hospital. Dr. Shahid, I'm so glad to have you with us today. I found this fascinating research. I'm really glad we're doing this topic and I've been looking forward to this podcast. Can you start with a little bit of the evolution of endovascular repair of aortic pathology in patients with aortic aneurysm? Why has this shown to be a bit prohibitive? Why the need for improved device design?
Dr. Zain Shahid: Yeah. Thank you, Melanie, for having me. So, overall, generally open repair has been the gold standard for a pair of abdominal and thoracoabdominal aortic aneurysms. Over the past three decades or so, however, there has been refinement of EVAR technology. And now that's available and there've been various commercial endograft systems that are now available. Many of those are now in their third or fourth generation. That has led to a transition of clinical practice from open surgical repair to EVAR in the elective management of abdominal aortic aneurysms and in some cases, thoracoabdominal aortic aneurysms. Currently, in the US actually, EVAR far exceeds open repair, especially out in the community.
Over time as this transition has happened, we have seen patients who've had endovascular repair done 10 to 15 years ago now starting having problems. That can mean they've had migration of their endografts, they've developed endoleaks, they're developed infections or other issues, that have required secondary interventions, either more complex endovascular repairs or open repairs.
Melanie Cole, MS (Host): Well, thank you for that explanation. So as more and more patients who would be deemed unsuitable candidates may be based on anatomic criteria, I'd like you to tell us now about physician-modified endovascular grafts. What are they and what does that mean when you say physician-modified? Does it mean custom design has been promoted with each device? Custom made for a specific patient? Please explain that to other providers.
Dr. Zain Shahid: Yeah. So physician-modified endovascular grafts is a term that's used to describe physician modifications or modifications that I make to commercially available abdominal and thoracic endograft. So that means creation of fenestrations or holes, direction branches. or scallops. It sort of depends on the patient's anatomy and what we are treating. So these devices are specifically made for each patient or modified for each specific patient. No two devices are the same and there are certain sort of ways how you modify those. And there are certain indications for this, which we'll discuss in a bit.
Melanie Cole, MS (Host): So I'd like to get right into that. And then tell us about the role of PMEG in the treatment of complex aortic aneurysms. Tell us about those clinical indications and patients selection.
Dr. Zain Shahid: Right. It is indicated for patients with complex abdominal aortic aneurysms, which includes juxtarenal aneurysms, pararenal and suprarenal aneurysms. It's also indicated for patients with a thoracoabdominal aortic aneurysms types 1 to 5, depending on what the patient has. They're also indicated in patients who have had chronic dissections with now aneurysmal dilatation and something that we see more and more commonly, it's also indicated in patients who have had failed prior endovascular aortic repairs, or EVARs or open repairs. These patients are generally not candidates for open repair. They're not candidates for commercially available fenestrated endografts, and they cannot be enrolled in industry-sponsored clinical trials for the new and upcoming endografts.
We do have a pretty strict inclusion and exclusion criteria. So I told you a little bit about what the indications are as far as, and obviously those patients are included in the study. But in addition to that, patients need to be 18 years of age or older and be able to sign consent for the procedure. There are very specific anatomical criteria that are also important. There needs to be a good proximal landing zone in the aorta of appropriate size. We also need an appropriate distal landing zone, either in the aorta or the iliac vessels of appropriate size. And then we need to have our target vessels, which are generally the visceral vessels in which include the superior mesenteric artery, celiac artery and the renal arteries to be of certain size to be able to put stents in.
In addition, the overall health of the patients is important. We do these procedures in hopes that we prolong their life and their aortic-related morbidity and mortality is decreased. So we do want to see that the predicted one-year rupture risk of the aneurysm is higher than the one-year mortality after repair, so in case we're doing a complicated operation, which will eventually prolong their life.
Melanie Cole, MS (Host): As far as challenges, Dr. Shahid, one might imagine that any device customization involves a time delay between patient sizing, manufacturer of the device, the implantation event itself. Tell us a little bit about how long currently the process takes in the best of circumstances and how you have found to be the case. How have you addressed this challenge?
Dr. Zain Shahid: Yeah. So that's a good question. So these modifications are made onsite at UF Health Shands Hospital, that is we make those modifications ourselves. So the grafts that are provided by the company are commercially available. We have them on stock. So there's no as such delay for a new graft to be made for the patient. We make the modifications the day of the operation.. So, for example, if a person comes in to clinic today and wants this operation, and he has a very large aneurysm and we think it needs to happen within a week or so, we can fit them in the schedule as soon as tomorrow. Generally, no one needs that kind of thing, but maybe even next week. And then what we do is every patient gets a CT. So we upload the CT scan in our special central line software. And then we take precise measurements to the nearest millimeter as to where the important branches, which I mentioned, which are generally the celiac, the SMA and the renals come off. And then you modify the graft the day of the operation based on those measurements. It takes me approximately one to two hours to make the modifications to the graft. And i usually start making the modifications before the patient is brought back into the operating room. And by the time the patient comes in, is intubated and has the appropriate lines placed by the anesthesia team, the graft is ready and we're ready to start the case.
Melanie Cole, MS (Host): Wow. That's absolutely fascinating. Now, I'd like to address the elephant in the room, Dr. Shahid, for other providers, does there exist a legal risk to modifying an existing FDA-approved medical device? Does this involve product liability? Can you speak to other providers about this portion of this?
Dr. Zain Shahid: Yeah. That's a good question. So this is considered an off-label repair, no doubt about that. And I am very clear to my patients and our consents are very clear about that. Again, we are only offering this to patients who are not candidates for an open operation, not candidates for sort of commercially available endovascular grafts, fenestrated endovascular grafts, and can not be enrolled in clinical trials. And these patients understand that. And we get special refferals with the understanding that that's what they will be getting.
Now, we have sort of collected some data over the last couple of years, which we are planning to submit to the FDA to try to obtain an investigational device exemption. So we can do these procedures under the umbrella of a clinical trial. I think that will expand our indications and allow us to treat more patients as well.
Melanie Cole, MS (Host): Is there a difficult learning curve to what you're doing? You said it takes you a couple of hours to modify the device. Are there technical considerations you'd like to share with other providers to help them achieve better outcomes should they head into this?
Dr. Zain Shahid: So, yes, I think there is a steep learning curve for this. These procedures are generally done at sort of large academic centers, because it's not just me, it's a whole team to be honest. So you need to have good anesthesia staff. You need to have good nurses. You need to have good. Surgical techs, good IR techs and A good ICU team to sort of understand what we're doing. The modification, like you said, takes one to two hours. And I think over time I've sort of become faster in doing these. I think initially, when I was in training, when I was doing these, it took me three hours or longer to modify a graft.
Really the most important thing about modification is your planning. So when you do your measurements on your CT scan, they need to be really accurate. And generally, what we do here at UF Health Shands Hospital is I make my own measurements, and there's a second person and sometimes a third person who does their own measurements. And then we compare. And this is to the nearest millimeter to make sure that our measurements are accurate. And then we make those modifications and there are multiple ways to make modifications. I mean, people do it a little differently, but what we've seen and we've had good results with is just reinforcing our fenestrations with the PTFE or Teflon and we put special coils around them that allows us to see them really well on the fluoroscopy. So I think I think it's not easy for people everywhere in the community to do these cases because of the support needed and the complexity of imaging required. So for those reasons, most of these patients are referred to pick a tertiary or quaternary care centers, and there very few of those that are actually doing these operations.
Melanie Cole, MS (Host): That's a great point that you made. And I'd like you to reiterate that as we wrap up. I'd like you to first tell us how your outcomes have been and where do you see this going in the future? Do you have final thoughts for physciains as far as immediate device modification and how it really, as you just said, should be performed at centers completely familiar with all advanced endovascular, aortic and visceral artery techniques and a high volume of these fenestrated procedures.
Dr. Zain Shahid: Right. Yep. So the outcomes, so our outcomes over the last two years have been excellent. We've had no deaths in the first 30 days, which is amazing. Our target vessel cannulation, which are our SMEs, celiac and the renals has been close to a hundred percent. Spinal cord ischemia, which is a major risk with complex aneurysms, specifically large thoracoabdominal aortic aneurysms has been less than 3% to 5% in our series. Secondary reintervention rate for endoleaks or aneurysms proximally or distally has been less than 5% to 7%. In addition, the incidents of major cardiac events, renal dysfunction, stroke, et cetera, and other in-hospital complications have been low. But of course, I think this all seems very rosy, but I think as we continue to do more cases and gather more long-term data, I think these numbers are bound to change.
And then as far as sort of closing statements, I think this is a really complex operation. I think straightforward endovascular repairs, infrarenal repairs, absolutely can be done anywhere in the community, people who have basic understanding of aortic pathology. This requires team effort. This requires a lot of complex sort of planning, equipment and it requires a lot of knowledge in how to, A, do the operation and what to do if the operation doesn't go well, I mean, it's bound to happen at some point where you're in a spot where you're not sure what to do next. You need sort of your partners that have an understanding of how to deal with those issues. And you need to have experienced with those issues. And that can only be done in places who do a high volume of these cases. I think if you're doing one or two of these a year, I think the outcomes are bound to be not that good, like with any other sort of complex operation. We've now been doing one or two a week. So as you can imagine, we've had those complex issues, we've dealt with those and we thankfully have really good outcomes.
Melanie Cole, MS (Host): What an interesting interview this was. Thank you so much, Dr. Shahid for joining us today and sharing this incredible information and this incredible technique that you're using at UF Health Shands Hospital. To refer your patient for physician-modified endovascular graft for treatment of aortic aneurysms or to listen to more podcasts from our experts, you can visit ufhealth.org/medmatters.
That concludes today's episode of UF Health MedEd Cast with UF Health Shands Hospital. For updates on the latest medical advancements, breakthroughs and research, follow us on your social channels. I'm Melanie Cole.