Chapters Transcript Aortic and Endograft Evaluation Take Evaluation Thank you again. We'll move from the sublime to the ridiculous here. Um Just a note dr silo. In 1983 I learned carotid ultrasound from paul Cardew alot. Our office was right next to the vascular lab and he would lean over and here say here that and I'd listen here that's how high grade credit stenosis. So many of us learned this in the same way you have with T. C. D. Aortic and end a graft evaluation. Endovascular aneurysm repair has become the preferred treatment for aortic aneurysms in a period of only 20 years when it was first suggested by dr Perotti Vascular surgeons laughed. They said oh it won't apply to more than 10 or 20% now probably 70 or 80% of aorta aortic aneurysms can be treated with an endovascular approach. Um What we've learned though doing these procedures that lifelong surveillances required and there are multiple societal guidelines. The Society for vascular surgery, european, Society for vascular surgery. Society for interventional radiology. All uh mandate lifelong surveillance and that surveillance is done with a variety of modalities. C. T. Scan, M. R. I. Regular X ray color Doppler ultrasound and contrast contrast enhanced ultrasound. Now if you look at the graft manufacturer intention for use schedules they all recommend a C. T. A. At one month six months 12 months and then once a year and that becomes problematic. Now why would we even consider ultrasound. Well it can look at a number of things that a. C. T. A. May not be able to look at. So we can look at with our physiologic and our duplex evaluation graft latency or Qingqing or thrombosis, we can easily measure sac diameter. We can identify endo leaks. We can look at proximal and distal attachment sites and whether there's development of aneurysm above or below the graft and we can assess those graft attachment sites. Um There are five types of endo leak, ignore the fourth and the fifth. The vast majority are 12 and three. Type one is 1 a. That's the proximal uh seal zone. Type one B. The distal seal zone. And you can imagine if there's a leak there you really haven't done anything to stop the aneurysm from rupturing Type two or branch endo leaks. You have a good seal approximately and distantly but blood is getting back into the aneurysm sac either Yeah the most common ones are inferior as enteric artery or lumbar arteries. And then type three is caused. And we're seeing more of these now by a defect in the graft material or a disconnection of the two components of the of the stent graft. Now you could argue that the single most important piece of information. We do when we look at an ultrasound after ivar is look at the size of the sac. And we'll talk about why this is important because that really may be the only major indicator for doing anything. And as such if we take a 90° angle in the patient's body. We may not be measuring a true uh Cross sectional area or image of the aneurysm. And so we want to get that nice perfectly circular image that tells us that we're cutting that aneurysm at exactly 90° to the Aorta, not to the patient. Now we see in pseudo aneurysms, you're familiar with these wave forms, these to and fro or bidirectional wave forms. And this is something unique, especially to type two endo leaks. So this is flow entering in and coming back out of the area of leakage and we'll talk about that. So We'll go through them. Type one. Now here you see in the long axis and the short access the graft is actually moving so you can tell something's not right here. Uh And this is at the proximal end in our long access in color shows flow escaping before the stent graft itself and filling the aneurysm sac. This is not good. And this is something that we must treat regardless of the size of the aneurysm Sac. You basically haven't done anything to stop this from rupturing. And it's important to compare your color images, your ultrasound images and your C. T. Images because that may in fact help plan therapy. Now here's a type one B. This is a great study from R. V. A. Lab where you see on the left the limb of the one limb of the under graft has just pulled back into the aneurysm sac. And if you look on the ct image you see the end of that just sort of floating in the aneurysm sac. So this also basically is not doing anything to help prevent the aneurysm from rupturing and has to be treated. Now. Much more common are type two endo leaks. Now don't. These are um these are videos if if you can hit the video for some reason it's not running um there you go. And so you see flow beginning in this case posterior to the aneurysm sac and filling the aneurysm in the right hand picture in between the two limbs of the graft. This is typical of a lumbar, endo leak and then an I. M. And a leak. You see that nice to and fro. Image in the in the long axis. And again if you can hit the uh video on the right there you go, beautiful demonstration of the retrograde flow through the I. M. A. And backfilling the aneurysm Sac. Amanda in our lab took that picture. She's very proud of it. And again it's important to uh compare your your C. T. Although I'll talk a little bit later about how we've evolved from not necessarily doing cts on everyone. And then type three we do occasionally see you see in that lower edge the the extra visitation outside of the graft and in the plain X ray which is very helpful a disruption of or a fracture of a part of the stent we can also look at and a graph limp latency here. We see a kink in the graft and grayscale and we see it in color and we see a velocity elevation there all consistent with that ct finding of a static limb of the end a graft. So the SVS has a number of guidelines that they've that they've put forth and how to survey these bypasses and they talk about a C. T. At one in 12 months if there's a type two endo leak imaging again after six months if there's no second large mint and no endo leak perhaps moving to color Doppler ultrasound the presence of a type to end a leak should prompt continued cT surveillance. A new endo leak after prior imaging that was that showed no endo leak is actually a strong evidence to do something and only sort of towards the end of their guidelines. Do they suggest that color Doppler ultrasound or non contrasted cT can substitute for post of our surveillance and patients with chronic kidney disease. And they do strongly recommend we all follow these that every five years we should do a non contrast ct of the entire aorta because of the 10 to 20% incidence of uh aneurysm degeneration elsewhere. Of course the more normal studies you have the less likely you're going to have an endo leak. And we keep that in the back of our mind. But these guidelines bring up a couple of issues here. Medicare data showing the sort of unimpressive application of ultrasound for surveillance, only 25% by 2010. Um And the need for alternative surveillance modalities and intensity is multifold. Um It's driven by concerns about excessive radiation risk and the cumulative risk of leukemia or blood cancers, repeated contrast exposure and deterioration of renal function demonstrated a number of papers and nowadays cost, cost cost. So we began looking at this uh actually uh only five or six years after we began doing endo graphs and we looked at what was the clinical utility of a six month C. T. And we looked at 206 patients who had missed their six month CT scan compared with 3 376 who who had it. And there were no missed complications in the group. That treatment decisions were not impacted by the lack of that six month C. T. So we took a step ahead and a few years later we reported on 184 patients who were switched to color Doppler ultrasound at an average of 34 months and followed for a mean of 24 months and there was no aortic-related mortality and there were no missed complications. And so we've had a practice shift post ev are we now do a C. T. At one month and 12 months and we're even beginning to phase out the 12 months if our ultrasound study is normal. We do an annual color Doppler ultrasound afterwards. We do not make exception for endo leaks. As long as the sack size remains stable and the C. T. A. Has performed selectively. If a color Doppler ultrasound demonstrates increase in stack size that's probably the most important thing or a new endo leak. That didn't exist. We reported this and before our switch to color Doppler ultrasound only. We had about 24% of patients who were finding endo leaks on the C. T. Um The ones that we intervened on were type ones and one type two where the aneurysm was growing and a couple of patients treated with because of king king of the limb really has nothing to do with endo leak. And after the switch to color Doppler ultrasound only 10% with new endo leaks and only 5% were treated one a. or one b. These are the ones that we know we have to treat And six Type 2s and those were all related to sack enlargement. Five of these were treated without a confirmatory cT A. We went directly to angiogram and coyly and and three had a confirmatory C. T. A. There were no ruptures. There were no limit collusions and they're nowhere and there were no aneurysm related deaths throughout that follow up period. So we concluded that color Doppler ultrasound alone surveillance after one year is safe and affected. There is no aortic related mortality. It dependably identifies findings requiring secondary interventions and we did notice that late and Alex are frequent and they can and they can be diagnosed by surveillance with color Doppler ultrasound only just to mention about contrast enhanced ultrasound. These are two meta analysis or systematic reviews. The first looking at contrast enhanced compared to C. T. A. Uh And I'll just read here evidence suggests that contrast enhanced ultrasound postive are can be utilized as a safe and effective method and screening for endo leaks during surveillance without exposing the patient to additional risk of radiation or contrast. And it conveys no inferiority to C. T. A. In detecting and Alex. And then the second meta analysis comparing C. T. A. Color duplex and contrast enhance both the contrast and Hanson cd you were specific detection of type one and three and Alex, I'm not sure why they didn't really want to commit themselves to the type to the most common and estimates of their sensitivity were uncertainty were uncertain but there was no evidence of a clinically important difference. And therefore we can say that C. D. U. Detects type one and three and the leeks with sufficient accuracy for surveillance. After eve are lastly we're now doing fevers beavers. The number of acronyms increases every year. These are finished rated branch devices. This is why we're able to treat the majority of aneurysms now with stent graft and dr Zeller from that strand. This lab that was so famously mentioned and dr Gordon's first talk has begun to look at these and has found that protocols after fever beaver and FB. Var. I don't know what that is. Um can be based on these duplex findings established for standard Ivar along with assessment for the administration's and the branches and Patton C. Of the renal and Mesen Terek arteries. So color duplex ultrasound is becoming established as a reliable surveillance tool after Eve. R. It is not inferior to cT angiogram and has no associated risk of radiation contrast exposure and it's cheaper. It can safely be instituted as dependable surveillance policy. But we have to keep in mind. It's a time intensive complex study. It's not available in every vascular lab and we have to keep that in mind. Not every ultrasound department will do a complete Eve our study. I stayed in my time. Thank you. Created by
