Hello, my name is Terence Case. I'm the Program Director and Assistant Professor for the Vascular Sonography Program at Nova Southeastern University in Fort Lauderdale, Florida. I also chair the Products Committee of the Society for Vascular Ultrasound along with Billy Zhang and George Bodejo. This program is being supported by an unrestricted educational grant from the Radiology and Vascular Ultrasound Division at GE Healthcare in cooperation with TIP TV. I'll be providing a brief overview of the SVU professional performance guidelines and then Dr. Phil Bendick will provide a comprehensive presentation and demonstration of the aorta iliac duplex examination. Dr. Bendick will then return to demonstrate these techniques on our patient model. These guidelines were prepared by members of the Society for Vascular Ultrasound to provide a working template to aid vascular technologists and other vascular professionals. The purpose of this examination is for the evaluation of aortic iliac disease and its effects on blood flow dynamics using duplex ultrasound technology. Common indications for this study include pulsatile abdominal mass, history of hypertension or family history of abdominal aortic aneurysm, also known as AAA, surveillance of a known AAA, Medicare screening for abdominal aortic aneurysm very efficiently, referred to as the SAVE Act, back pain, evidence of distal emboli, and finally evidence of inflow arterial disease or surveillance of arterial vascular intervention and or reconstruction. The most common contraindications for this examination include a large firm abdomen, the presence of significant bowel gas, open abdominal wounds, and pregnant patients in their second and third trimesters of gestation. To prepare for the examination, the patient must be NPO after midnight. The patient should not chew gum or smoke the morning of the examination as this exacerbates the production of bowel gas. Be sure to advise patients who need to eat, such as the diabetic patient. In general, early morning appointments are beneficial in these cases. The guidelines include abdominal aorta iliac duplex evaluation, assessment of abdominal aortic aneurysm, endovascular aorta iliac stent graft evaluation, and aorta iliac occlusive disease evaluation. These guidelines also provide a review of diagnostic exam findings, the presentation of exam findings, exam time recommendations, and recommendations for continuing medical education. For a comprehensive list of all SVU exam protocol guidelines, please visit our website at www.svunet.org. Thank you. Hello. I'm Phil Bendick, the Technical Director of the Peripheral Vascular Diagnostic Center and Director of Surgical Research at William Beaumont Hospital in Royal Oak. Today, I want to talk to you about the Vascular Technology Professional Performance Guidelines published by the Society for Vascular Ultrasound regarding the aorta iliac duplex ultrasound examination. The purpose behind this examination and the purpose for having the guidelines is the evaluation of aortic and iliac arterial disease and its effect on blood flow dynamics using our duplex ultrasound instrumentation. We're going to talk about a number of topics today. I just want to summarize them very briefly before I go into greater detail. We will discuss the indications for these examinations, what contraindications may exist and the limitations of these examinations, patient preparation and patient communication issues, the positioning of your patient, the assessment of your patient. Spend a great deal of time on the examination technique itself regarding examinations for aorta iliac obstructive disease, abdominal aortic aneurysmal disease, and the postoperative evaluation, particularly in those patients who have had endovascular stent grafts placed. Finally, we will present a review of the findings, how to present those findings to an interpreting physician, recommendations for the time it should take to perform this examination, and finally, a few comments about continuing professional education. First, indications. The patient may have a palpable or pulsatile abdominal mass on physical examination. The patient may have a known peripheral abdominal aortic aneurysm. There may be evidence of distal small embolic disease, or the patient may present with lower back pain. These are all characteristic of aneurysmal disease. Alternatively, a patient may present with leg pain with walking or exercise, what we call claudication. They actually may have leg pain at rest or resting pain, or there simply may be an abdominal or a groin brui heard on physical examination, all findings characteristic of more obstructive lesions. The patient may be seen for surveillance of known pathologies, such as obstructive disease, aneurysmal disease, or some prior intervention that has been done. Screening for abdominal aortic aneurysmal disease is also a good reason for doing this examination in an appropriate patient population, and there are other less commonly seen pathologies, such as dissection or aortic coarctation, which may indicate the necessity for this examination. There are certain relative contraindications and limitations to the study, obviously. If there is an open abdominal wound, you will not be able to place your transducer at that site, or if there's recent abdominal surgery, the patient may not be able to cooperate fully and do all the things you need them to do in terms of positioning during the course of the examination. Also, if there's a peritoneal catheter in place, such as used for dialysis in some patients, this will significantly limit the examination as well. Pregnancy is another relative contraindication, but it should not be considered an absolute contraindication in that if the study is to be done, at all times simply remember the ALARA principle, that is as low as reasonably achievable, limit the duration of the study and limit your output power during the course of the study to safely examine the pregnant patient. Other limitations we're also very familiar with, the patient may have large body habitus, there may be extensive bowel gas present, which will limit the ultrasound penetration. Also in the abdomen, it is very important to recall the limitations of your Doppler angle. You must be at 60 degrees or less. Many times the abdominal aorta, in particular, appears at nearly right angles to your imaging angle, so you get a very poor Doppler angle. This will significantly limit the study and affect the quality of the velocity data that you do achieve. Also, the patient must be able to cooperate during the course of the study, as they will need to be holding their breath at certain intervals, and they will also need to reposition themselves at certain intervals during the course of the study to obtain the best data. Preparing the patient is not terribly complex, but it is an important part of the study. These studies should be scheduled in the morning, simply because you want the patient to be NPO and not eat or drink anything after midnight the night before the study. On the way in to having the study performed, particularly in the outpatient setting, perhaps the most important instruction you're going to give the patient is no smoking, no hard candy, or no gum chewing prior to coming in for the examination. As any of these activities, while the patient may not view them as eating or drinking, certainly will allow a large amount of gas to be ingested into the GI system and will interfere significantly with your ability to obtain a high-quality study. There are exceptions, obviously, to the no food or drink after midnight rule, particularly in diabetic patients. They should have their normal diet, they should take their normal medications, and anybody requiring medications should take them at their normal time with simply very small sips of water. This is perfectly all right prior to the abdominal study. The aortic iliac examination may still be successful on a patient who is not NPO. You are going to have less success in these patients as a general rule, but even if the patient did have something before they came in, it is worthwhile to at least start the examination and see what you're up against, as you may be able to successfully acquire all of the data you need for proper diagnosis and interpretation. Finally, the patient should definitely try to wear loose clothing when they come in for this examination, or in the case that they don't, just have them change into a standard patient gown before you begin the examination, and this will make everybody's life much easier. As a vascular technologist or sonographer, there are certain things you should be telling the patient ahead of time. First, obviously, you need to introduce yourself to the patient and say, hi, I'm Phil, I'm the registered vascular technologist who will be performing your study this morning. Explain the reason for the examination. Why was the patient sent in? What did the physician find that caused this study to be ordered? And at the same time, explain a little bit about the non-invasive nature of the ultrasound examination and what the patient can expect. Indicate approximately how long the examination normally takes and also tell them there may be exceptions. It may be shorter, it may be longer, but typically this examination will take 60 minutes, whatever it is your laboratory protocol standardizes upon. And we have found that the most important thing you can do in terms of patient satisfaction, and this is based on actual patient surveys, be certain that you respond to any patient concerns or questions as fully as possible. This will leave your patient with a very good feeling about your facility and the study itself. You can, at the same time, try and educate the patient regarding some of the risk factors for atherosclerotic and aneurysmal disease. You also can educate the patient somewhat about the signs and symptoms they should be looking for for these diseases or if they have already had an intervention done, what some of the signs and symptoms of interventional dysfunction might be. You should refer very specific patient questions on the particular diagnosis, the particular treatment, or the prognosis back to the patient's physician to be fully answered. You may think you know the answer and you're probably correct if you're an experienced technologist. However, you want to be sure you are sending the patient a very consistent message throughout the management of their disease process, and this one single consistent message is best delivered by the patient's referring physician. Once you have the patient prepared, they're on the examination table, you'll start with them in the supine position. You can elevate the head slightly if you need to for comfort of the patient and, again, put a pillow under their head if necessary. As long as they are comfortable in the supine position, that's probably the most important factor. Remember also that during the course of this examination, you will be moving the patient around and it may, in fact, be absolutely necessary to use some of the lateral decubitus positions to acquire the data you need because there may be some overlying bowel gas, you may have depth penetration issues. There are a lot of things that come up, particularly in those large patients, which may limit the study and you will need to go to the lateral decubitus positions, such as is seen here, when you roll the patient up onto their side, either the left side or the right side, or in my experience in most examinations, you're going to be doing it on both sides, looking for that best acoustic window to penetrate down to the level of the aorta and particularly the iliac arteries. The assessment of the patient will be performed prior to actually initiating duplex evaluation. You want to establish that there are no significant contraindications to the study or if there are relative contraindications, you have taken those into account in planning your study protocol. You need to take into account, particularly in those patients who have had recent abdominal surgery, their ability to tolerate the entire duration of the procedure and again, you may need to adapt your specific protocol to that. Also, a relevant history and physical assessment should be done. Of very much importance is your ability, if possible, to review any previous imaging studies that may have been done, be it ultrasound, CT, MR, angiography, any type of imaging study that might be available for you to look through the patient record, as well as any operative notes or previous clinical visits the patient might have had, so you have a complete history available and you know what it is you're looking for. This will aid immensely as you adapt your standard protocol to a specific patient's condition. When you think about the patient's history, particularly their vascular history, their previous surgeries, what their current medical status in medications and treatments might be, all of that go into your planning the procedure and acknowledging what it is you're looking for. You want to make a brief review of what their vascular risk factors are for your own clinical record and particularly any signs or symptoms of aortoiliac disease as we discussed earlier under indications for the study. You also want to verify the appropriateness of the current order. It is rare, fortunately, but not uncommon. A patient will be sent in for swelling in a previous inferior vena cava filter and yet an aortic study is ordered when in fact they meant an ilio-inferior vena cava venous study to be performed. If it is part of your laboratory protocol, finally, in your assessment of the patient and their history, a very brief measurement of the ankle brachial indices may be in order as this will assure you the status of the outflow system in this particular patient and it may in fact have been ordered by the referring physician in any case, but it is worthwhile looking at those ankle brachial indices during the course of the examination. As far as the examination itself goes, there are a number of general guidelines that apply regardless of the underlying pathology at which you may be looking. You certainly want to adjust your scanning technique throughout the course of the study to optimize your image quality and your spectral Doppler and color Doppler waveform and flow characteristics. I call this the technical side of the study and you're emphasizing, if you will, your left brain during this part of the examination. At the same time, you want to keep your clinical skills sharp during the course of the study and analyze all of your data as you go in case you do need to adapt your standard laboratory protocol to include additional information so that you're certain that all the necessary data is acquired for a complete diagnosis. This is your clinical cognitive skills. This is your right brain at work during the course of the study. So you can see that your brain is not going to get any rest during this study. You're going to include both lobes throughout the course of the study and be concentrating fully on the patient at hand. You of course want to use appropriate instrumentation for B-mode, spectral Doppler, color Doppler, power Doppler. Most of our modern ultrasound equipment can handle this study technically if we choose the right probes and instrumentation. You want to select the proper and appropriate imaging and Doppler frequencies, remembering that you may have to allow for additional penetration in those large patients. On the other hand, this is ultrasound. There are tradeoffs to be made and a good general rule to follow in ultrasound, both for imaging and Doppler, because it increases your signal strength, is to use the highest frequency possible for imaging and Doppler, subject to the penetration limitations that may be there, as this will enhance and improve your signal quality dramatically. Whenever you measure the size of the lumen or the size of a blood vessel, the recommendation now is to actually use the long axis view. This is simply because you're assured of scanning along a true diameter when you have a good, proper long axis view of the vessel, so you know you are measuring a true diameter. The measurement should be made from outer wall to outer wall and it should be made perpendicular to the direction that the vessel is going. Again, this is most easily accomplished in a long axis view. You can certainly supplement the long axis view with transverse views and this is highly recommended as well. The measurement in the AP direction from a transverse and a long axis view should be the same. You assure that by making sure in the transverse view that you have very good, strong specular reflections off the walls, because this tells you that you have a good 90 degree incidence with your ultrasound beam and you're getting good, strong specular reflections back. If you do not see those strong specular reflections coming back from the vessel wall, it means you probably have an oblique incidence on the vessel lumen with a transverse view and you're going to have a somewhat distorted shape of the lumen. It may be somewhat elliptical in shape, but your diameter measurements will vary and be inaccurate if that is the case. So it's an important consideration to be sure that you're using the proper long axis view and you're measuring from outer wall to outer wall for your diameter measurements. Color doppler is used to supplement spectral doppler. It will help you identify accessory and branch vessels off of the abdominal aorta. It will certainly help you identify the iliac arteries when we get to that segment of the examination. It gives you a good visual display of flow direction, defines the residual lumen in those cases where there's atherosclerotic obstruction or, for example, thrombus contained within an aneurysm sac, and it will identify vascular versus non-vascular structures, and detect very low flow conditions as well in these vessels. A few more comments about breath holding. You must remember that you're dealing with patients who will only give you a few good breaths. Now, if all of our patients were beavers, life would be good. A beaver can take a breath in, you can do your study, about 45 minutes later, the beaver needs to take another breath, but you have all of your data complete and your study is finished by that time. We are dealing with humans. Your typical human patient is going to give you, even with a good effort, less than one minute of breath holding, and they aren't going to do that very many times. Typically, you can expect a patient to hold their breath for 10 or 15 seconds for a number of times during the course of the study, but not much longer than that. Anecdotally, just for your information, the world record for a human breath hold is just under nine minutes, so keep that in mind too. So, you only get a few good breaths category. Do not have the patient take in a deep breath and hold it. What happens is they might give you a good effort the first one or two times. They won't give you very good efforts after that because it's too much work for them. The other thing that happens, and it really is detrimental to the quality of the study, is if a patient takes in a very deep breath and holds it, their abdominal wall tends to become very rigid and firm, and you are not able to push as you need to with your probe. You're struggling against the patient, working against what they're trying to do, and it is very counterproductive to a good quality examination. On the other hand, it is very simple. If you coach the patient through a couple deep breaths in and out, a deep breath in and slowly out, and after a couple of these, coach the patient, take a deep breath in, slowly let it out, and when your breath is about halfway out, just stop breathing. Every patient understands this instruction with no difficulty, and if they just stop breathing for five or 10 seconds, the abdominal wall remains soft and pliable, it's compliant when you push on it with your probe to achieve that data you need, and it becomes a much easier examination for both you and the patient as they feel they are working together with you to accomplish this examination. You're not fighting them with their rigid abdomen. In order to make this work, you have absolutely got to optimize all your measurement controls before they stop breathing. That is to say, put your Doppler sample volume out in your image approximately where you will need it to be. Make sure your Doppler sweep speed, your Doppler scale, your Doppler gain are set where they need to be before the patient gets into their breath-holding maneuver. Make sure your B-mode gain and all of those controls are set up appropriately, so that when a patient stops breathing, you can move your sample volume to the region of interest in the vessel, you can turn on your spectral Doppler, you can acquire your spectral Doppler waveform in the matter of approximately five or six seconds, certainly less than 10 seconds, and then the patient can breathe normally again. It keeps the patient relaxed. It allows you to get the quality of data that you need, and is a very good technique to use in the abdominal study. The other thing to remember is this is technically a challenging and difficult study. Don't frustrate yourself during the course of the examination. If something is not working, go to the next part of the protocol and then come back to this at some point later during the course of the study. The iliac arteries in particular, and again, where the common iliac artery bifurcates into the external and internal iliac arteries, or the hypogastric artery as it's often called, are particularly difficult areas to image well. When you see an artist's conception of the aortic and iliac bifurcations, you tend to see a relatively straight line, two-dimensional drawing as their perception. This is not the reality. The reality is a very tortuous system. It lies deep. The internal iliac arteries come off the common iliac arteries at unexpected angles many times. The iliac arteries may in fact be involved with aneurysmal or obstructive disease. And on top of everything else, because it's atherosclerosis, there's a certain amount of wall calcification involved, which makes your imaging that much more difficult. So remember, the iliac arteries are a tough segment of the examination. Accept that. Don't frustrate yourself and try and struggle through something that just can't be done. With that in mind then, as far as imaging goes, remember, low transmit frequencies provide good penetration. You want to optimize your color Doppler settings to help identify the location, flow direction, and flow quality in the iliac vessels particularly. You remember to use the lateral decubitus positions. If you cannot get a good image of the iliac artery bifurcation when the patient is supine, roll them up on your side from that lateral decubitus position, either a flank approach if you need to, and see if you can get a better shot of the iliac artery on one side or the other through that position. And the last thing to remember is you want to approach the iliac bifurcation both from above and below. If you're scanning down the aorta through the aortic bifurcation into the iliac arteries, scan from above towards the iliac bifurcation to see what you can accomplish. Also, you can go down to the level of the groin and scan from below through the external iliac artery back up to that bifurcation. And in one of those two cases, you're likely to get a good view of the iliac system, and it may be a composite of both of those. Certainly, you want good data storage techniques. Most hospital-based systems are now in some type of PAC system. It's not an issue. If you're in a smaller office setting, you want to make sure you have good quality storage not only of your still frames, but there are certain instances that electronic video clips you will want to store with good resolution as well. An example shown here with a dissection, which is a dynamic phenomenon. You want to see that dissection flap move with the cardiac cycle. You want to establish beyond a doubt that there are two separate lumens with two very distinct and different flow characteristics throughout both of those lumens. So here, a cine clip is invaluable documentation, and you want to keep that in mind as well. Well, let's move on to specific disease states. Let's talk first about atherosclerotic disease, often abbreviated ASO for arteriosclerosis obliterans. But in the obstructive disease, you want to think about a couple different possibilities for measurement. You can document a greater than 50% diameter reduction if you find an area where there is a focal jump or increase in peak systolic velocity of a factor of two. So whenever you see anatomic narrowing, measure the peak systolic velocity at the site of that narrowing, and then measure the peak systolic velocity at some relatively normal site proximal to that site of narrowing. And if that ratio exceeds two for those peak systolic velocities, you know you have a greater than 50% diameter reduction. As well, if you do that same thing and you look at the peak systolic velocity ratio and it exceeds the value three, you know you are dealing in all likelihood with a hemodynamically significant stenosis. That is one which causes a measurable pressure drop and should have overall impact, for example, on your ankle brachial index, so it should be diminished in a patient like that. These are two different ways of looking at the same phenomenon, that is atherosclerotic obstruction. The first, the focal doubling of velocity, simply relates to an anatomic reduction in lumen size. The second one, a tripling of velocity at a focal site of narrowing is a physiologic or functional way of looking at the disease in that particular patient, and it allows two different ways of looking at the same process. In your B-mode image, pay attention to the abdominal aorta from the diaphragm all the way through the bifurcation through the iliac arteries, all the way down to the level of the groin, the entire abdominal aorta and iliac system. You should adhere to a standardized protocol, at least to begin the examination. You may have to adapt that protocol as circumstances dictate through the course of the examination, but your laboratory should have a starting point of a standardized protocol that everyone can follow. Remember, your spectral Doppler will be supplemented by color Doppler throughout the aorta and the iliac arteries. In B-mode in imaging, you of course want to document the dimensions of the vessels involved. Again, remembering to measure in long axis from the outer wall to outer wall. If there are any sites of narrowing or dilation of the vessel, you certainly want to document those. And if you see plaque, any other abnormalities such as thrombus or dissection, be sure to document the presence, the extent and the characteristics of these particular lesions. The iliac arteries should be examined throughout their entire length from the aortic bifurcation to the groin. You want to document the origin of the internal iliac arteries, often called, as I mentioned, the hypogastric arteries. And if there are any anatomic or pathologic abnormalities, these of course should be documented in your B-mode image as well. Doppler will be used to document patency of the important vessels, not only the aorta and the iliac arteries, but some of the major branches such as the celiac trunk, the superior mesenteric artery, the inferior mesenteric artery and the renal arteries bilaterally. Certainly you want to document the common iliac, external iliac and internal iliac arteries as well. You will want to record representative waveforms from all these sites of interest, whether they are stenotic or non-stenotic, as well as any waveforms from sites you might see of dissection, the presence of thrombus or any other abnormalities you might find such as flaps, pseudoaneurysms, small or subtle wall defects. Any region of abnormality should have not only B-mode image documentation, but spectral Doppler documentation as well, supplemented by color Doppler. Certainly at sites of stenosis, when you're talking about atherosclerotic disease, you want to measure your peak systolic and end-diastolic velocities at the site of stenosis, proximal to that site, as well as distal to that site, looking for any evidence of post-stenotic flow turbulence. Always keeping in mind, use a Doppler angle of 60 degrees or less and angle correct parallel to the walls. A little tip about angle correction I can throw in at this point. If you use the far wall of the aorta or the iliac arteries on which to base your angle correction parallel to the walls, it is the one that is best visualized and most easily visualized and will give you the best and most reproducible data in terms of your velocity measurements. ♪♪ Moving on to the evaluation of abdominal aortic aneurysms, lovingly referred to as AAAs. The definition of an aneurysm is simply when you have a dilation of a blood vessel that exceeds 50% more than the native vessel lumen itself or a 1.5 increase over native vessel dimensions. In males, an easy number to remember in this regard is simply if you see an aortic diameter greater than 3 centimeters, it's probably aneurysmal given the typical size of the male aorta. Remember, however, in females, they tend to have somewhat smaller vessels, so this is not going to be the case. A female may be aneurysmal before they reach the 3-centimeter mark, and it should be so noted. Again, as an atherosclerotic disease, your evaluation should adhere, at least at the beginning, to a standardized protocol, but always be ready to adapt it as conditions dictate. Your B-mode imaging will, again, include the abdominal aorta from the region of the diaphragm all the way through its bifurcation through the iliac arteries to the level of the groin, just as previously, and you're going to document the diameter of these vessels and the associated branches in the suprarenal, juxtarenal, and infrarenal positions and any abnormalities that may be there. You want to obviously measure the site of greatest dilation, as we talked about earlier, using a long-axis view first, measuring outer wall to outer wall perpendicular to the vessel lumen, and then supplement that with your transverse views. You should also measure these at peak systole to be consistent from one examination to another. You're going to measure, as I mentioned, in long axis, supplement them with transverse views, but only if the lateral walls are seen clearly will you make the transverse measurement in a particular case. You can, in a situation like this, you're going to use your spectral and color Doppler to document vessel patency throughout the system of interest and obtain your spectral Doppler velocities at sites of suspected pathology as well. Again, always remembering to use Doppler angles less than 60 degrees and angle correct parallel to the vessel walls. Color Doppler imaging will supplement your spectral Doppler data as well as help document the presence of any interluminal thrombus, which is oftentimes seen in the case of aortic aneurysmal disease. It will document the residual lumen and the presence of any stenosis that might be there, as well as any other pathologic abnormalities such as dissection, intimal flaps, or whatever might be present. As far as post-intervention studies, I want to focus most of my talk on the endovascular stent graft patient. Again, adhere to a standardized protocol. This is particularly important in these patients as they've had a complex procedure and there are a number of things unique to endovascular stent grafts that you want to try and look for and measure. Particularly, you want to evaluate and document the position of the stent fixation sites, both proximal and distal. This is a device that has been placed through percutaneous means and it had to be affixed to native vessels, some were in the proximal abdominal aorta and some were distally, either in the distal aorta, iliac, or femoral vessels. You want to make sure that you adequately evaluate the apposition of this prosthetic stent to the native vessel walls. The endovascular stent grafts come in a variety of shapes, forms, and types. They may be unibody, which is to say a one-piece endovascular stent graft. They may be modular, in which there are a number of parts and pieces to the stent graft, which are there and assembled inside the body using percutaneous catheter-based techniques. It could be a simple tube graft just in the abdominal aorta. It could be an aorto-biliac or bifemoral graft going down both limbs. Or it could be an aortic uniliac or unifemoral bypass graft, in which case the contralateral iliac artery has been ligated or embolized or thrombosed in some fashion and taken out of the circulation. You want to look at the proximal attachment site and document where it is relative to the renal arteries. It may be below the renal arteries, as is typical, or in fact, it may extend above the renal arteries or a transrenal fixation, in which case the stent graft will have some type of open framework over that region so as not to obstruct flow into the renal arteries themselves. This is an example of that type of open framework. You can see extending above the graft material itself so that the stent graft can be affixed above the renal arteries without obstructing renal artery flow. The distal attachment site will need to be evaluated as well. The best place to find out where this is is have access to an operative note. If not, you will have to determine that with your duplex ultrasound examination. It might be, as I say, the distal aorta. It might be the distal common iliac arteries, or it might be the external iliac or common femoral artery. That will have to be determined. And the actual shape of that distal attachment may be a bell-bottom shape such as this, or it may be open prongs affixed into the vessel wall itself. All of those will need to be determined during the course of your study. Because the aneurysm sac has been left in place with endovascular stent graft repair, it is still there, and you need to document the size of this aneurysm just as you would in a native vessel evaluation. Good long axis and cross-sectional viewing with careful measurements of the maximum lumen size, outer wall to outer wall again, and making sure there have been no changes, or ideally there's been a decrease in aneurysm sac size from any previous studies you may have available. You want to very carefully evaluate any areas you might see within the aneurysm sac that appear echolucent or pulsatile, as this may represent an area of so-called endoleak in which there is residual arterial flow within the aneurysm sac, which makes the patient at risk again for aneurysm rupture and its consequences. You want to document the flow and the patency in the renal and the visceral vessels as well to make sure that they have not been obstructed during the process of graft placement. And look at the flow characteristics throughout the body of the stent graft itself to make sure that that has not become twisted or is kinked or is itself causing some type of flow abnormality. You are then going to spend a great deal of time in this post-interventional evaluation looking for the presence of endoleaks. This is blood flow outside the graft lumen, but still contained within the aneurysm sac. They come in four basic types. The type one endoleak is an endoleak associated with either its incomplete attachment at either the proximal or the distal attachment site of the stent graft itself. A type two endoleak are those associated with aortic branch vessels, such as the inferior mesenteric artery or lumbar arteries, in which those vessels have stayed patent and there's retrograde flow from those vessels into the aneurysm sac. A type 3 endoleak applies to the modular endovascular stent grafts in which at the point of connection of one or more of the modules, there is incomplete attachment and there may be a leak of blood flow at that site. And finally, the type 4 endoleak is early on, the graft material may have some porosity and blood may leak through the graft itself. Later on, there may be actually a mechanical or structural defect in the graft material and the graft material actually is leaking flow into the aneurysm sac. These are the four types of endoleaks that you're looking for and it's best to always keep that in mind. You're going to look at them with both spectral and color doppler imaging. Once you've assessed the graft fixation sites, look very carefully for any flow which might be outside the graft lumen. You're going to assess the residual aneurysm sac completely and thoroughly throughout in both sagittal and transverse views for any evidence of endoleak and document the velocities. Remember at this point, you're looking for very slow flow, so you want to optimize your color doppler imaging controls for very low flow sensitivity while you search for the endoleaks. And also do not forget to turn up your color doppler gain as high as possible before you get into flash artifact problems. You're going to want to document the patency of any branches which come off the aneurysm as such as the lumbar arteries or the inferior mesenterics or if the endograft extends down into the iliac arteries, the patency of a covered internal iliac artery. You also want to be very careful about assessing flow direction in these branch vessels. You want to record the waveforms obviously from any region of extra graft flow for complete documentation both within the aneurysm sac and from any associated aortic side branches. Well finally, you've completed the examination. Then what do you do? Well, you have to review the findings first to make sure that they're complete. Make certain that you have acquired all the necessary data, that you've done a comprehensive examination, that all of the data one needs is there to make a complete diagnosis. If there are any exceptions to your protocol, you should at least on your worksheet document these. And it's helpful to explain this information to the patient as well because they may come back with these questions and say, why did they not tell me this was not a complete study? So feel free to explain these limitations to the patient themselves at the time they're there. It's good public relations and enhances goodwill throughout. You also want to obviously document all of the data you acquired during the examination and record all of your technical findings as completely as you can. If there are any findings that you have that warrant immediate medical attention, be certain that a phone call is placed to the referring physician and possibly your medical director as well so that these actions can be implemented in a timely fashion in the interest of good patient health and safety. You then have to present all of these findings to the interpreting physician. You want to present them following your laboratory guidelines and provide all of the data from the duplex examination, the worksheets, and any technologist or sonographer comments that are appropriate to the examination so that the interpreting physician has all of the data necessary at their disposal. As far as the time for this examination, it breaks up into two parts. That is the direct component of time in which you are actually dealing with the patient, optimizing equipment, acquiring data, positioning the patient, actually doing hands-on scanning, the fun part of the examination, if you will. This can take anywhere from 60 to 90 minutes. The indirect components, the paperwork, the pre-examination assessment of previous data, review of records, patient preparation, positioning, patient assessment, and the post-examination preparation of all of your data and findings to present to the interpreting physician typically require about 30 minutes from this study. The math is not terribly difficult, and you can see this is a complex examination taking approximately 90 minutes on average for most patients and possibly up to two hours in a difficult post-operative patient. Finally, I cannot emphasize enough your continuing professional education to stay current in the field. You need to maintain current in your knowledge of what are the diagnoses and treatments for these diseases. Have standardized examination protocols changed out there, and do our laboratory protocols meet these standards, and do we use appropriate diagnostic criteria? You want to stay on top of advances in ultrasound technology and be able to utilize these new technologies to their best effect in the examinations that you perform, and as well, any associated technologies such as might be present within the hospital PAC system that you can utilize to your own advantage. In summary, it comes down to become certified, remain certified, and stay connected. I'm very happy to say this picture is my own wonderful collection of registered vascular technologists in my own laboratory at home. They're all SVU members as well, and I encourage you to do the same. Thank you very much. Let's show an actual demonstration of the principles of the aorto-iliac duplex evaluation. We have with us a real patient, which is helpful. It will show a lot of the principles in this particular examination. By way of history, a patient with relatively long-standing high blood pressure, which has been treated medically, has a history of previous smoking, the ideal candidate, and the person about which the SAVE Act was designed, an aortic aneurysm was discovered as part of a workup for a different medical problem. It was followed clinically. When it exceeded about five centimeters in size, the decision was to repair the aortic aneurysm. This was done with an endovascular stent graft, an example of which I have right here. You can see through the right groin, the main body and right limb of the stent graft was placed. Through the left groin incision, percutaneously, the left limb of the graft was placed. This was joined in a modular fashion, which I can do right here, a balloon expansion right at the junction, sealing the proximal and distal attachment points, excluding the aneurysm from the circulation, and leaving an aorto-bioliac graft behind. Let's turn to the actual examination. We have the patient lying supine. We'll liberally apply gel down the midline to start with, and I like to start the examination with a brief cursory review in black and white, B-mode imaging, and color doppler, just to get a feel for the anatomy and what we're going to be up against. In this particular case, we see on the image, I'm just below the level of the diaphragm, see some small gas bubbles, which are typical in these patients. Hopefully they will not be in the way during the entire examination. I'm getting a brief glimpse here, get my arrow on there so you can see it, of the abdominal aorta, the proximal segment of the aorta. We'll show this in color doppler in just a few seconds so you can see it more clearly, but I want to just briefly scan down the midline. There's the aneurysm, there's the two limbs of the aortic endograft, scanning down right to the region of the aortic bifurcation, coming across a relatively large gas bubble in this case, which we'll work around, get below the gas bubble, into the iliac arteries, and you can see here the bifurcation, the iliac arteries splitting off, and then they head off as they will in a very tortuous fashion, and we'll be following those in long axis. Looking in long axis very briefly, going back up to the proximal aorta, and again, the easiest anatomic landmark typically to find is the aneurysm sac itself and the limbs of the stent graft, which you see very clearly here, and our friend, the local gas bubble, you can see the continuation of the aorta above that, and follow the proximal aorta up towards the diaphragm, the superior mesenteric artery coming up, the abdominal aorta down here, and you can see, again, as is typical of an endograft patient, because you put a fairly rigid graft inside a native vessel, it will take some sharp turns and twists as you go, so do not be surprised by that, the native aorta here, the endograft ending up here. In looking at this with color, again, switching to a transverse view, turning our color Doppler on, we just very fortuitously, and it's hard to beat good luck in this examination, but there's our celiac trunk, the native aorta is going to be down here, I'm going to move my color box down just a little bit to incorporate that region, again, you can see some good color filling here of the native aorta, and as we scan in cross-section, little peristalsis there, maybe turn our color gain down just a little bit to get away from some of that, still have native aorta, there's our little gas bubble again, we're going to emerge on the other side, native aorta, and this is where the aorta now becomes a little bit tortuous because of the implanted endograft, and you see much more proximally now, the residual aneurysm sac, and the limbs of the endovascular stent graft, continuing again, remember this is just a brief survey, down through, anatomically see where things are, get to the aortic bifurcation, see the iliac vessel split off, and splay quite wide to either side of the color region of interest, and then in this particular view, lose them to further sight, returning to a long axis orientation, and again, the best landmark we have in this particular patient, the aneurysm sac itself, we can note one of the salient features of this aneurysm, is if you look at the aneurysm itself, though it's technically classified as a fusiform aneurysm with dilation in all directions of the arterial wall, this particular aneurysm, as we'll notice here, has a lot more anterior dilation than posterior dilation, and the potential there is because there's more dilation against this wall than the other wall, there's the potential for more thinning of this wall, and theoretically at least a higher risk of rupture, and this is one of the considerations which went into the endovascular repair of this aneurysm when it reached a size of five centimeters. The other thing we now see in our long axis view is the tortuosity, we've got a relatively stiff endograft in place with an elastic vessel, so there's almost a discontinuity in the flow direction here, though there is a smooth transition from the main body of the graft to the two limbs of the graft, where you see the bright echoes is where you really start to see the overlap of the modular characteristics of this graft. Other thing we notice is very proximal in the aorta, just below that area of the gas bubble, I'm going to go ahead and freeze the image since I get a reasonably clear view of that proximal aorta, and while I have that particular image in view and no gas overlying it, I'm going to go ahead and take a proximal aortic measurement right at the attachment site, and go ahead and acquire that documentation and store it in system memory. So I have that bit accomplished at this point. Whenever you can see something that's part of your protocol in a study like this when you know there are going to be gas bubbles present and potentially moving around, go ahead and acquire that data. It will necessitate going back at the end of the study and reviewing things to make sure you have all of the data you need, but it is sort of my bird in the hand theory of vascular ultrasound in this particular case, is when you have the opportunity to get some data, go ahead and acquire it even if it's not in the exact order in which your protocol was written. And we go to our pulse wave, adjust our scale appropriately so we can get a waveform. I'm going to turn our gain down just a little bit. But again, characteristic of a proximal aortic waveform, we see a very good sharp systolic rise. We see a well-defined systolic peak. We see a little bit of sustained diastolic flow, which is characteristic when you're above the level of the renal arteries. So at this point, we would measure our peak systolic velocity, store that data, and move on from there to a more thorough evaluation. Moving in cross-section to the site near maximal aortic dilation, finding that site, and then pivoting the probe to bring it up into a long-axis view. This is now the recommended methodology for measuring dilation of vessels and aneurysm size, is a long-axis view where you display the vessel end-to-end as best you can, assuring you're going across a true diameter. Once you have the image you're satisfied with, freeze that image, go into your measurement mode, and remember we're measuring from outer wall. Place that cursor as best I can to outer wall, perpendicular to the direction of flow and the lumen in this case. Measuring that, we would record that dimension of 5 centimeters, which is slightly smaller than the CT scan measured preoperative size. We confirm actually the limb size. We go in in a cross-sectional view. We will go ahead and confirm that the limbs have not made any changes. It would be very surprising since these particular limbs have a metallic structure, but about a 13 millimeter limb size, which I'm sure is what was implanted in this patient if we went back and reviewed the operative report. The last thing you want to do while you have the aneurysm sac in view is do a very careful survey looking for any potential endoleaks. For this, we're going to turn color on. I'm going to go ahead and I'm going to widen my color box so I have a relatively large region of interest so I encompass the entire aneurysm sac. In cross-section, I'm going to go up until I see native aorta, which is in the image right here. Then I'm going to slowly track through. Once we get into the aneurysm, I'm going to go ahead and turn my color scale down to make myself sensitive to very low flow. I've changed my color scale from 21 to 10 centimeters per second. I'm going to turn my color gain up so that I'm sensitive to any Doppler flow signal changes. This will introduce more motion artifact and noise, as you can see, but if there is any slow flow within that aneurysm sac, I want to be able to see and detect it. Now, this particular aneurysm, as the preoperative CT scan showed, does not involve the iliac artery, so we do not have that to deal with and worry about, but we do, in fact, want to follow the limbs of the graft down to make sure there are not any problems with that. Right here is the end of the right limb of the endograft. So at that point, bring your cursors up. Again, mark that point. Take that measurement. Again, 13 to 14 millimeters, the original size of the endograft place, so that all correlates. As you then proceed to image, where the endograft ends is where the vessel becomes very, very tortuous. The endograft ends right here, and this is where now the iliac starts to dive very deep. It's going to be very difficult to follow. So we've seen the right side. Let's go back up to that bifurcation point again, right below the umbilicus. Angle now over towards the left leg and follow the other limb. One point to note about this particular examination and the aorto-iliac examination in general is you notice I have not had to have the patient do a lot of breathing exercises or holding their breath, anything like that. When you have large vessels like the aorta or an aneurysm or the iliac arteries, they tend to be relatively fixed in position, even during the respiratory cycle, and it's not necessary in many, many cases to have them do a lot of breath holding, such as you need when you're looking for the small renal arteries or some studies such as that. So in the aorta-iliac examination, you may once in a while want to have the patient hold their breath or stop breathing, but typically it's not necessary during this examination. That's one of the nice features of this because, again, the vessels are large and fairly fixed in place, and you haven't seen a lot of respiratory variations and changes as we go throughout the study. So in summary, we've had an opportunity to look at the native vessels. We've seen the proximal aorta. We've seen the native iliac arteries. We've had an opportunity to look at how they are measured and documented. We've had an opportunity in this case to see an endovascular repair of an aortic aneurysm, so we've been able to evaluate the proximal and distal attachment sites. We've seen the modular connection site. We have seen the aneurysm sac itself and been able to document its dimensions and all of the flow hemodynamics associated with the endograft. Now had this been an open repair of an aneurysm, we'd have done things very, very similar. The only difference would be there would not be a residual aneurysm left behind. We would be looking at just the graft structure itself, looking at the proximal and distal anastomoses, but our documentation in terms of anatomy and hemodynamics would be very, very similar. So we have been able to show you in brief a fairly comprehensive review of the aorta-iliac examination, and I thank you for your attention. www.ottobock.com

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aorta iliac duplex examination

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aortic iliac disease

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