Okay thank you. We are going to continue along on the abdominal duplex I hope. Okay so briefly let's quickly review our visceral abdominal anatomy. We obviously have our abdominal aorta. We have our celiac superior and inferior mesons. Terek arteries, the celiac branches of the splenic and hepatic arteries. We have our renal arteries and veins and today we're not going to touch on a hepatic portal vasculature but that will briefly appear on the RPV eye exams. So again study that content outline the celiac trunk and the S. M. A. R. In close proximity. Sometimes they actually share a common origin off of the aorta. The renal arteries originate below the S. M. A. And both renal arteries are posterior to the renal veins and it's important to know that about a third of kidneys have accessory renal arteries. So one in three patients you need you're going to see multiple renal arteries. Abdominal visceral duplex imaging is really technically challenging and we rely on our technologists to get high quality exams. Patient preparation is key bowel gas is a major faux here we need an overnight fast and sometimes even a sim Ethicon preparation can help we're gonna use a low frequency ultrasound transducer of course to image those deeper structures In the belly. The angles are generally closer to zero than 60° but that's appropriate because we're parallel to flow and our lab our labs are gonna have different scanning protocols depending on the indication. Is that abdominal pain after eating. You're going to focus on the visceral vessels is an abdominal brew, you may image everything. Um is a drug resistant hypertension. You're going to focus on the renal arteries protocols again are going to vary depending on your specific indication. But in general we're doing extensive grayscale or B. Mode imaging to look at the vessels, look for plaque, aneurysm, dissection. Other things. We're gonna do extensive spectral. Doppler interrogation of the vessels and of course color. Doppler as well. And this is just a core concept. It's the every artery in the abdomen in different physiologic states will have a unique Doppler spectra. So you need to know expected patterns so you can detect when there's a problem. So low resistive pattern in the normal state will be the aorta. Above the visceral segments. So above the celiac and renal arteries you're gonna have some diastolic flow. The renal arteries, the celiac trunk which is feeding the prank um organs of the liver and spleen and the S. And the S. M. A. And the I. M. A. And the postprandial state will viso dilate our high resistive vessels in the abdomen are the mid to distal abdominal aorta. The common and internal iliac arteries. The lumbar arteries and the superior and inferior mesons. Terek arteries in the fasting state. So I teach this a lot to the fellows. When we read, even the abdominal aorta will show different. Doppler spectra depending on where you're sampling. So above the celiac sme and renal arteries are right at that level. You're gonna have diastolic flow as we move distantly, we lose our diastolic flow, get more of a reverse flow component. And then finally, as we get into the iliac bifurcation, it looks like a limb artery very resistive. There's different windows. We can get to get these images. If you get really lucky on a patient, you might be able to do the whole exam, trans abdominal lee. How often does that happen guys? Very table This table here is never um here are angles are going to be closer to the 60 degrees. If we can image that's called the spider view on the left, Usually you're gonna need to go to Cuba this imaging right side, down, left side down and our angles there are closer to 0°. And often we do a combination of both in terms of duplex criteria for renal artery stenosis. We're looking for atherosclerotic plaque on the gray skull imaging. We're looking for a discrepancy in kidney scott size on grayscale imaging. If there is one kidney that's a centimeter and a half or more smaller than the other, That side is probably fed by a narrowed artery. We're looking for color and spectral. Doppler abnormalities. Color, a listing turbulence tissue and spectral breweries. And then of course, we're looking for velocity shifts. So we're going to measure peak systolic velocity and end diastolic velocity. And then we're gonna do our renal aortic ratio, highest renal artery psV divided by the renal, the aortic PSv at the level of the renal arteries. You want to do it at not above not below right at the level of the renal arteries. And we have some secondary parameters will briefly mentioned. These are criteria that are most commonly used or some variation. This is a publication from Jeff Nolan when he was at Cleveland Clinic a number of years ago that validated these criteria. Very broad categories here for renal arteries 0-59% or normal exam. PsV less than 200 centimeters per second. And that ratio less than 3.5. Then we have a Hema dynamically significant stenosis PSV. Greater than 200 centimeters per second. And that ratio greater than 3.5. And actually this study also proposed that if your tV. Is above 100 and 50 centimeters per second in a stone optic renal artery That indicates a very severe stenosis of greater than 80%. And then of course there's occlusion. I want to mention two caveats. You have to have a normal aortic velocity to use that are A are. So if you have a child with middle aortic syndrome and PSV's of 200 in the aorta can't use the ratio similarly if you have a big triple A. And you're a or at the level of the renal arteries and your PSV is 20. You can't use the ratio Gotta have that normal aortic velocity between 40 and 100 cm/s. And also know these criteria not validated for F. M. D. We don't put a number on FMD using these criteria. And briefly wanna mention resistive index. It's a cousin of the pulse utility index you heard about from dr scylla. It's a measure of parang kamal flow and we get this within the renal arteries and those parental vessels. And it's the PSV minus the E. D. V. Divided by the PSV. And if you have poor parents normal flow or very resistive signal your E. D. V. Goes to zero and that ratio goes toward one. And we see high resistive index in the setting of intrinsic renal disease, chronic kidney disease, diabetic neuropathy. Also a transplant rejected. I also want to mention a very low resistive index. Can indicate an inflow lesion or a hemo dynamically significant renal artery stenosis. And here you can just see qualitatively as well as quantitatively these resistive patterns and that resistive index normal on the left and a very high resistive signal on the right. And then one more parameter. We don't use that often which is renal acceleration time. It's the actual time to the initial peak on the PSV envelope. There's an older parameter than an acceleration time greater than 100 millimeters per second is significant with a severe stenosis. You really can get fooled by this very insensitive. So you can see severe renal artery stenosis with normal acts. But if you see a dampened acceleration time. Think about it. Am I missing an inflow lesion? And similarly, if you're getting printable signals and you only see uh you see a very dampened acceleration time in one part of the kidney and not the other. Think about an accessory or duplicate renal artery that has a narrowing. Mhm. Here's a normal duplex exam starting at the top. Excuse me left. Excuse me. And working clockwise. You can see normal patent, right renal artery and blue on color Doppler. And then we really systematically marched through and all our velocities. There are less than 100 and 50 centimeters per second, well below 200. There's no turbulence, normal and healthy and beautiful imaging through a trans abdominal approach. And again we measure the kidney. Usually get multiple measurements, get our parental signals and get our renal vein signal. Common to have pulse. It'll flow in the renal veins. Here's an example of renal artery stenosis. You can see some aliasing of the color signal there at about nine o'clock on the clock. Are PSV. Is 450 centimeters per second. In this case the renewal of the arctic ratio is seven so that we would call 60 to 99% renal artery stenosis. And in this case you can see the plaque and you can see turbulence of the color flow and beyond the stenosis at the origin. You're going to want to see turbulence which you can see here spectral broadening and then you see a little bit of dampening as we move distantly and note in this case um on the right side we did have renal artery stenosis but the acceleration time there was normal very crisp up stroke and it's not the time to the full peak. Not where you measure PSV. It's the time to the initial peak systolic velocity. Here's a case of very severe published case actually renal artery stenosis. I saw early in my career this patient actually had an aortic dissection and had very bad hypertension. Her PSV was almost 800 centimeters per second. E. D. V. Was 480. This is the most severe renal artery stenosis I've ever seen are er was 11. Um And you can see that spectral brew. We as well. Another indicator of all the turbulence. This one with that E. D. V. You could call probably a greater than 80%. Here's a case of F. M. D. You can see here with turbulence in the mid to distal vessel indicating FMD and. Okay very briefly. Mesen terek duplex. Um Just want to mention these studies need to be done in the fasting state after you eat a meal. You actually get a change in waveform and peak systolic velocity can also go up. So these should be fasting studies. Here's an example of a normal mesen terek duplex with our beautiful celiac trunk and S. M. A. You have low resistive flow in the celiac trunk because it's feeding the hepatic and splenic artery's. Those also have a low resistive flow pattern. R. S. M. A. Usually has a high resistive pattern. This one has a little bit of diastolic flow but you have that reverse flow component. And then R. I. M. A little guy is always like one or two o'clock on the clock in the transverse view. And we have diagnostic criteria for these arteries for celiac artery stenosis. Here we really are correlating to more severe degrees of stenosis at which you'd intervene. It's a PSV above to 50 indicating a greater than 70% stenosis. And for the S. M. A. And probably the I. M. A. PsV. About 2 75 into creating a greater than 70% stenosis. And here's an example of an S. M. A. Stenosis. First of all, the waveform is low resistive, unexpected in the S. M. A. You can see the very high velocities over 300 you see a spectral broody and this was a patient who just had abdominal had abdominal brulee, no abdominal pain. But she had severe disease. She had her celiac artery was occluded and you can see gotta really dropped the color scales is probably too high to prove an occlusion. But color power angio showed no flow in the celiac and there you can actually see retrograde flow in the paddock artery going to supply the splenic artery, common collateral pathway. And then she had very high. Velocities in the S. M. A. Consistent with 70 to 99% stenosis and the I. M. A. And you can see there are a lot of tissue brulee artifact as well as a spectral brewing on the spectral display indicating a severe stenosis and a lot of collaterals. Just to wrap up here a couple of quick RPV. I questions how would you interpret this finding in the celiac artery? Is this normal? Greater than 70% stenosis? Greater than 80% stenosis Or can't tell. Need more information, anybody. Okay dr. Levinson can't tell need more information when she of course is right. The celiac artery gotta be aware of the an atomic variant of median argument, ligament compression where you get dynamic compression of the celiac artery and often the S. M. A. Especially if there's a common trunk by the diaphragm. In this case you have elevated velocities in the celiac artery that normalize with deep inspiration. But also sometimes you actually have to stand the patient and have them take a deep breath. And you can see here there's a little kink in the in the artery that when the patient takes a deep breath actually uh straightens. And this is a controversial clinical entity. It's very common to see this on ultrasound rarely can it cause a clinical syndrome with postprandial abdominal pain and weight loss. And here's some just really nice examples from the team at ahuja of patient with celiac artery compression. You can see elevated velocities at baseline that crimped artery that aliasing of the color signal. Deep breath in artery diaphragm kind of goes away from the artery artery straightens out velocities normalize. And just for your exam please be sure to know your non atherosclerotic esoteric artery disease. Also didn't have a chance to touch on renal and mesen Tarek stenting that may show up on the exam. So again, review that content outline here are a few entities on the top. You can have F. M. D. In the S. M. A. It's usually in the more mid to distal vessel. Here's an example of an S. M. A. Dissection and of course you can have visceral aneurysms among other entities. So please review that contact outlining the specific competencies. Thank you.
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