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carotid duplex scan

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Summary

In this expert-led on-demand teaching session geared towards medical professionals, they will delve into best practices and techniques for conducting a carotid scan - a critical procedure for examining the carotid arteries that supply blood to the brain. Learn the different ways to perform the scan, either from the front or back of the patient, the optimal positioning of the patient during the scan, and how to effectively use probes to visualise the innominate and carotid artery's origin. The session will also cover in-depth the techniques to identify the internal carotid artery (ICA) and the external carotid artery (ECA), which can pose difficulties for even seasoned practitioners. Furthermore, they will identify key signals to look out for, such as diastolic filling and Doppler waveforms, to assist with these distinctions. The session also teaches practitioners how to identify and grade plaque lesions, which are markers for atherosclerosis changes, accurately. Understanding the differences between hypoechoic and calcified plaques and their potential risks will empower practitioners with better decision-making skills while treating patients. Finally, the session will touch on the importance of accurate diameter reduction, accurate stenosis grading, and how it affects patient diagnoses and treatment plans. This teaching
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Description

carotid vascular duplex scan

Learning objectives

1) Understand and apply the two different methods of performing a carotid scan, including position and probe choice. 2) Identify and define the differences between internal carotid arteries (IC) and external carotid arteries (EC) on a carotid scan, including size, positioning, and waveform. 3) Recognize the signs of the stenosis and occlusion of arteries in carotid scans, and understand the implications for patient care. 4) Correctly calculate diameter reduction and grade plaque on B mode helping in the grading of stenosis. 5) Correctly apply color in scanning to identify the length of plaques and distinguish between hypoechoic plaques and the lumen of the artery.
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The following transcript was generated automatically from the content and has not been checked or corrected manually.

Or stenosis of the subclavian and can cause an ipsilateral stain. So your B mode evaluation and there are two ways to do carotid scan. You can do it from the uh the blader aspect or let us say the front of the patient like what he's doing here or you can do it standing from the back of the patient. So you stand behind the patient and you do the cox scan sometime you do it while the neck in the middle position. But sometimes you can ask the patient to look to the right hand side or to the left hand side. When you start, you, you want to get the origin of the common carotid artery. Uh in this area, you need to look to see the supra clavicular notch. You can use the linear probe or you can use the abdominal probe, something between 2 to 3 megahertz can give you some, you can use, you can use a coronary growth which uh uh can also delineate deeper structures. So uh both ways are OK. And both uh probes are OK. As long as you can see the innominate and you can see the origin of the common carotid artery should begin with the B cephalic, making sure that you have seen the subclavian origin. Well, and then you proceed to look at the common carotid artery in transverse. Now, that's the common carotid in transverse, nice and pulsating. If you notice my uh BP is too much so that the jugular vein is compressed. If I loosen the pressure, you can see the jugular vein lateral to the common carotid as I go up and up and up until it bifurcates. Now, normally the b so the first step is to do transverse section and you go up at this area, you should see the level of the bifurcation. Usually at the level of the mandible or very low down. Some people have a high bifurcation. If you want to do carotid end arthrectomy, you do dislocation to the mandible and sometimes uh have a low bifurcation. But this is essential. And in some center, they do carotid d scan immediately before carotid endarterectomy to make sure that the carotid artery has not uh thrombosed uh or completely closed this side by side, the two branches, the two branches of the common carotid lie side to side. Normally, you have the IC which is more lateral and EC which is more medial in this case. However, it is anteroposterior. So if you notice the AC A is more anterior, the ICA is more posterior. So the first question, which is internal, which is external and this is very common question and you will face it. Usually the bigger artery is the internal, the artery in continuity is the common carotid artery is internal. Usually the artery where you get a diastolic filling, which you mean even in the vas there is filling is internal healing. Now, the artery which is a smaller, which is lateral, which have branches. The first one is the superior thyroid artery or the artery which does not have a diastolic feeling. It is is external. In most cases, it is easy, but in some cases, it is difficult. What will help you is the B mode, the color and the Doppler waveform, you should uh do the three. Yeah. Now there are ways to know which artery uh is the ICA and which is the AC A and it is important for us to know as well because at times when the one of the arteries is blocked, it becomes a dilemma as to which artery are we exactly seeing at this point in time. So you have differences between the IC and the AC. Normally the IC is larger infused against and the AC is relatively smaller in caliber I A is more lateral. IC is more medial, but in this case, the IC is more posterior. Also, if you trace the AC A, you realize that the C A has branches in the neck, whereas the IC does not branch in the neck. And when you switch on color. It's a sterile thing. No, the EC A is actually pulsating whereas the ICA reveals more or less steer the beam state she street the IC is fairly more continuous flow. Now, you got to realize that in this section, I had to keep the beam straight to visualize the ICA. That's because the axis of the IC is becoming perpendicular to the beam at this point in time. OK. So if I am seeing an artery which is making an angle to the probe, and if I give an angle correction, I'm actually compounding the angle. So when you compound an angle, you lose information, I just want to show it to you again. If I steal the beam, I may lose the information. But if I'm keeping it straight, I am fairly seeing the artery in a much better way except at the point where you will have the beam which is perpendicular and wherever the beam is perpendicular by the Doppler equation, you will have no flow. Notice here, this is the internal and this is external notice that in the arteries there is a very high flow. So in the internal iliac artery, which is a bigger artery, you usually see color across the whole cycle while because this have low peripheral resistance in the brain, while the external is a pulsating artery, which mean in the there is no feeling, it feels only in history. And sometimes you can see the speed is less. And in the three, sometimes you don't see any flow at all. And this is the difference between them. But fairly, you will see that the IC is larger pulsating and has a more continuous flow than the AC which is pulsatile. And lastly, the difference would be on Doppler, but I'll come back to it later on. Some of the other tests we used to do in the old days was the machine was not good. It's to do tapping on the temporal arteries, superficial temporal artery. When you do tapping to superficial temporal artery, which is a branch from the external carotid or AC A, then you get this transmitted pulsation into the AC A, you wouldn't get it into ICA. But uh very few people do this test nowadays because the machine can give you really very good information. You can see here, even the wall, you can see how smooth is the wall. You can measure intima media thickness if you want and you, if you want to get pressure, uh uh the big systolic velocity, you must have a sampling exactly in the middle, not near the edges because we know that we have a laminar flow. So the highest speed will be in the center of the blood vessel. So on the B mode, once I have seen the carotid artery and its bifurcation, I'm supposed to watch for the plaque lesions, all the atherosclerotic changes in the carotid arteries which starts from the common carotid artery. And you see, and this patient too have very nice, smooth intimal layer. And we are supposed to look at this intimal layer more so in the carotid artery in the internal carotid arteries, because that's the common site of occlusion which can give rise to smoke. So we are looking at the intimal thickening intima uh layer there and we're supposed to look for blocks and grade plaques for anyone doing carotid Doppler. It's a must that you follow the carotid Doppler consensus statement where you are supposed to grade plaques on B mode into type one, type two, type three and type four, type one and two being hypo type three and four being more calcified. Type one is more potential for causing plaque ulcerations and uh and therefore emboli and therefore, they are unstable plaques. Whereas type three and type four are more stable plaques that eventually uh that uh potentially cause less of thrombotic occlusions. So once you have graded those plaques, you're supposed to look for diameter reductions. Now, in this patient, because the carotid lies much, I will have to go from a lateral aspect to get the internal carotid artery in a transverse position. Once I've gotten that, I've got to freeze the image and ask my machine to help me calculate the diameter reduction. So for the diameter reduction, you placed a set of calipers on the outer margins of the wall and uh another set of calibers on the inner margins of falls. If you have a plaque on the inner margin of the plaque, and the machine will tell you that give you a diameter reaction there, which is approximately a 24%. Now, when you take uh uh diameter reduction and ensure that you are in the true transverse view, if you try to take it in a longitudinal view, you can foreshorten the values and therefore make sure that you are in a good B mode. If you try to take it in color, there's a potential that the color may mask the uh plaque and you can actually underestimate a stenosis. So therefore, diameter reduction is strictly taken in a transverse section in B mode, inner to inner and outer to outer. And the machine does the calculations for you. So grading of stenosis by this method is the is sort of useful only if the diameter reduction is 50% or lesser. If you have a larger block, then you should know who is describing how you classify the stenosis in ICA. This is the most important question for carotid DPSY scale. Is this patient have significant more than 50% or nonsignificant below 50%. And if it is above 50% how much it is and the characterization of the plaque, the method that you use the diameter for reduction is not that accurate. What is very accurate is the peak systolic velocity when it is more than 220 centimeter per second. This is very accurate about significant stenosis. More than 50%. You get a different data. If you go up to more than 90% to 95% the main thing is to keep the angle, the Doppler angle to be 60 degree and the machine will have, will have an automatic act velocities to grade the stenosis. But if it is less than 50% the diameter reduction is a much more uh accurate way of assessing the stenosis, then I have switched on the color and begin my tracing again from the common carotids. Now, the machine has preset. Normally, when you choose a carotic preset, the machine shows the common carotid to be in the red color, ensure that your box is just covering the vessel. And you see good wall to wall flow with normal use the moment you decrease your gain settings, you will start seeing a liaising. OK. Which is absolutely not desirable. Yeah. So now I'm going to ask you to increase the gain. So that yes, that's good. I can see good wall to wall flow in a uniform color you. This is what I need the most a wall to wall flow because sometimes type one plaques which are entirely hypoechoic may be missed on B mode because they are so absolutely the same ecogenicity as that of the lumen. But a color will actually identify the plaque and color helps you to identify the length of the plaque. What is the information you can get? The carotid artery is patient, it's not occluded. There is no stenosis, which is also very important. The wall abnormality. If there is a thickened wall, like an autoimmune disease like Takayasu syndrome, sometime you discover it also aortic dissection, aortic dissection. You will see a flap in the middle of the artery and the carotid aneurysm. So there is a lot of information you can get from the carotid DX scan. Besides just the flu, not only this but sometimes you see nearby pathology, you can see goiter in the thyroid. You can see single nodule, multiple nodule or even carotid body tumor. All this also can be seen beside the pathologies that you're looking at the common carotid artery. So when you're looking at the actual length, color helps you create that negative contrast with the plaque. Therefore, uh allowing it to be seen very well as an hypo filling defect within the color filled lumen of the vessel. When you look at the color, you look for points of leasing flow channel narrowing and leasing are again signs that we may probably deal with the stenosis. So looking for that is an important finding and then we switch on the uh spectrum, yeah, lying which you mean you get different types of color collected. This means that you don't have a laminar flow. So when you get sing sometime this will happen, if you get the carotid artery stenosis because you have lost the laminar flow. And you have what is called current current. If you have stenosis, you will get very high flow with very high speed and rusty and you get d current which is a very rapid thrust to blood in multiple direction. And this is the cause of es you want to tell you that es before you see the stenosis may be an indicator to see the stenosis. Because the new machine, you can see the stenosis very, very easily. So the spectrum imperative that we have a good angle correction. This is an ed carotid artery. So my angle is going to be parallel to the vessel wall because this is a lamina flow pattern. I know that the flow is going to be parallel to the vessel wall. And therefore my angle is set in that way that it is parallel to the vessel wall. But in the point of stenosis, you have to actually look at the leasing jet and keep your sample parallel to the leasing jet to calculate accurate velocities. This is extremely important in to calculate accurate velocity. Look here it give you the angle and a lot of the machines, the two machines that we have here in the unit, they have an O angle. So automatically the machine will get you 60 degree angle. So any measurement that you will get will be already corrected with the angle correction carotid because your uh grading of stenosis is based on velocity criteria. And the grading of stenosis depends which patient goes for medical management and which in which patient a surgical indication is suggested. So therefore, everything depends upon a good technique and it is is a good angle correction spectrum. OK. So this is a good normal waveform of a common carotid artery, common carotid will have features of both the uh external as well as the internal carotid. And therefore, you have a good forward s uh systolic flow. And so here we said there is a wave form for external carotid, which does not have diastolic feeling. And there is low resistance flow in the internal carotid. Now, in the common carotid, it's a combination of both and it will gradually differentiate into both. So even if you take the first one centimeter of ICA and first one centimeter of EC A, you found it's not a big difference. But if you follow them through, then you can see the big difference. A deep uh prediastolic notch progress to the bifurcation, steer the beam, try and get the a carotid. A carotid does not supply the brain entirely. There's only one branch, the middle meningeal which supplies the brain. And therefore, you expect a medium resistance wave from there where you have a good forward diastolic flow and a deep prediastolic notch again. So this is a sign of a medium resistance artery. And EC is a typical example of a medium size artery. And if you want to confirm it is a ec, all you need to do is do the spectrum. All right, and give pressure on the sorry, tell me, hello. Yeah, take it there. Just keep pushing the triggers there. And you will see the reflections of changes in peripheral resistance of the superior temp superficial temporal artery being reflected in the diastolic flow component of the AC. This is a confirmatory test that it is indeed an AC. And this is important when your the ac gets occluded and you see only one vessel and you have to determine which is an external or the internal carotid artery. So uh if having seen the medium resistance wave form of the ACI, am now going to show you the normal waveform of the IC, can I just take the spectrum? Yeah, uh scale down. So if you look at the IC, it has got a good forward diastolic flow. Now, this is a signature of an internal carotid artery that it is supplying the brain, which has inherently a low resistance circulation. And therefore, the diastolic flow is high. And if you see there's a clear gap between the waveform and the baseline, saying that the wave, the velocities are never zero in the internal carotid artery and the flow is always forward. Even when the heart is dilating, the diastolic flow is still forward towards the brain. This is a signature of an internal carotid artery and whenever you have stenosis, you have to ensure that your angle correction is right, so that you measure the velocities and then grade the stenosis according to the consensus report, it is graded into less than 5050 to 69 and 70 above. So this is important that your angle correction is extremely relevant. In this case, vertical has a similar waveform as that IC and has to have the same um flow direction as that of the common carotid artery. So here is the vertebral artery, you can see the vertebral artery below and this is the cervical spine and this is what we're going to see because the vertebral artery passes below the common carotid artery in between the inter spinous process of the cervical spine. What? So here I am seeing the vertebral in between the transverse processes. If you look at the transverse processes, I see the vertebral artery in red and the vertebral vein in blue. And if I take my probe further to the common carotid artery, I see the common carotid in red and the vertebral in red. So you can see the vertebral artery, vertebral vein, interspinous process because the vertebral artery passes inside the intervertebral process. So there is interosseous part of the vertebral artery. And this is characteristic, the main thing that the vertebral artery is patient, it's not occluded and there is no reverse the flow. So the flow is going up, which means there is no steel phenomenon. That means it is confirming that both of these vessels are going towards the brain. You can pick up a complete sub cleaving still by looking at the color changes here. Once you have done and confirmed that the vertebral is seen, it is of normal caliber and it is the same flow as that of the common carotid. I proceed to put a spectrum there. Again, you're ensuring that a good angle correction is done there. And if you see it's, it reveals a good forward diastolic flow, almost similar to what we have been seeing in the internal carotid arty. So make sure that the vertebrals are seen uh very well decrease and they need to be searched for in between the transverse process on B mode alone. You can see that very well. If the vertebrals are not seen, then probably it could be hypoplastic, which is a normal variant or they could have a stenosis at the origin of the vertebral artery or a occlusion of the vertebral artery. But it is easy to look at the vertebrals just uh between the transverse processes. And similarly, you're going to trace the left side as well. Thank you so much for your kind attention. I have learned. Thank you very much. Uh This was a quick video about how to do carotid duplex scan and um a carotid artery is, is the subcutaneous artery and uh a lot of intervention and the procedure are done in the carotid artery. And it's one of the very common uh diseases found in peripheral vascular disease. And it warrant um a simple easy repeatable investigation, which is the carotid public scan we will see with the three vascular consultant we have uh today with the on site. Uh they will do the carotid scan and we'll get the information from them and the significance of this information will take um 5 to 10 minutes break. And then we're going to go for the hands-on uh live session to carotid duplex. I wish you all the best you know about him. One doctor, he's uh doing a scan. Yeah, he will make it on the sets APA machine to carotid scan because the second thing is already been done. Let us start by asking, show us the origin of the common carotid artery from, from the anomaly. And then what is the PTO and the common carotid eye? B? Yes, that's a very good view if it is heart patient and this is thyroid gland. This is the pleth smal muscle, this is skin and this is the skin that is the most and he is now at the base of the um this is the beginning. It just on the we we make this from SS excellent. Mhm We try to get it in the middle of the screen and then I fell up questions. Inflammation, brilliant, brilliant, can decrease the color because the color up into tissues. So this, we need to lower uptake like this sometimes lower the beginning in order to be because when the disc is move, it pick up as if it's a blood vessel. So here I will try to lower the intense, little bit in order to prevent the risk and breathing. This is the, this is all this looks. Now, we can see clear the tissues. Now, the hand, this is Steve and, and this is the color, it's a big color and see it's spinning. Let us have the pictures. Excellent. Can you tell it's up to 80 centimeter per second? And what about the automatic? And in the middle of the well done you can get a much better picture of this but you can measure the so we'll stop this and then we can remove color. Yes. And then we can have Z show me the ant me, we go for measurements and then OK. Ok. So you want to please? Yes, yes, please and then measure yes and show me with. Yeah. OK. This is all drinking re 0.8 which is the maximum number for sickness to set that up to 0.8 to one of the risk factors. Like a br measure the excellent, brilliant and not a lot of people that you see this, but we are like that. So when I go to a difficult question, which is internal, which is what is the patient? So as you can see he's now sonograph his right hand on the, on the artery, his left hand on the keyboard, he got all the information he want right now, I got two arteries. OK. Which is, this is the one, but this one usually the bigger is IC, the smaller is the external carotid artery. If we put, we get some more information and now it should right away to see what he looks good and we put it great plan. So is this in? You don't rely on something with your lateral some kind of change, especially with Acsis. So if I want to get one of these arteries like this brilliant, then I will I need and information. Yes, hello. OK. And you can still up the window because if you have the blood flow during this, you wear out so you fine. OK? And to let you feeling weird like this, OK? Now you can see this is the color is. So if the color is going this way, I want to still this way. Now to me, it looks like something because a last is no better but to be sure that we are still near to the patient and for patients not far away with the and let us see the wrist, I need to be right away from the bifurcation. So if I want to measurement of a at least take one inch, one centimeter, you need the measurement there cause the arm to the combination, it is look to be external. There is a but it is very low and goes up and down in the inter you see this spinning up to work was my conclusion from the color the disc. Yes. And it's been, I hope that you can see the picture here on the screen with the color uh by the video. Maybe it's a little bit far away. I at least and this is the other article, know what to say. OK. OK, good. So this is you said fe on the head let internal usually is so yeah, you try, I think you try. Yeah. Not easy. Fish, fish have a high Yes, this is beautiful. You can see from the color. The color doesn't go away. It's always there. That's beautiful, well done, well done. Now he manipulated his group to be with yes, with the vessel and see the color. It never fades away. So there is always a flow in the ba it and listen to the f I hope that he can listen, you can listen to the people. Absolutely. If you're able to get it sometimes, no, he is breath. So this is external. It cannot be internal. You will not get any and you can see the word. Now he's able to get external. You too. And I'm always amazed the skin, the hand, the skin of surgeon, it always amazes me. They pick up very quickly. Now here you can see. Do you see but this is internal ra yes. And it's uh angle at 60 degree 60 degree angle and it is 50 around 6570. This means there is no stenosis, there is no acino. It's normal. Now let us go to the, the difficult part to get me. Yeah. Ok. No. OK. You need a water that's getting exactly is to get this view and then you're going to do rocking, you scan until you see the color I do. And then down, that's really so because a certain level you see it, it's not immediately below it, it around this area that's good. It's, it's not easy, not easy at all. Yes. Yes. It looks, looks, looks like it because the common carotid should be up here and here is, this is a because no artery is found below the common carotid. So again, fantastic. He wouldn't have to get the whole from them because it's a cautious art and there is interspinous process. One will be here, one will be there. So this is, and this is the, the main thing is the color is red. So it's going up. So there is no skin phenomenon in this place. Excellent. I'm fasting. OK. Forget the other. The same on the right side. Two will do the same common stand right hand side as a consultant. OK. He has broke his hands inside. Oh OK. Yes. Oh, so you can see now uh II would like you to comment on the what is a common cough? Really, really common cough? Excellent. Beautiful. Ok. Now you are low down. So you are artery. If you go down, it's quite where it, but sometimes it is difficult because your heart has a very base of the neck. Yes. Excellent. This is where it comes from. Beautiful. So you can go up. So, no, you, ok. Now, section to, no, he's blue color because the skin or let me see this is here and sometimes it is in there just uh it, it doesn't matter but maybe if you shift to very. Yes, that's it. OK. Again, start gradual and when you rotate, make it middle of the street. Don't graduate in the middle of the street. Yes, good. It's win feeling the wrong way. And then I would ask to measure the cost when you start the me your hand close and fix. Very good. So uh let me show where is internal, where is internal, where in the mind is it low division or high division? How is the blood work again? Try to know story. Then you can follow it is what you call divide in the two. I'm not sure which, which I know this one is bigger. It looks to be IC it have a little bit of rotation blood and this is probably stellar and this is probably brown but I'm not sure it isn. You compare it by and no, don't measure on T ST S your P will never become active. Always measure it on your if Yes, yes. Here it's very difficult to maintain. Very good. But what is good? Yes. Mm What signal is this external? No, there is still feeling you can see the flow in exist disappear, which is black color is external. No question about it now, internal. It is difficult. Yes. Yes. You can see, I know the inter from the color, the color does not disappear. Yeah. If you need to see it, yes, I can see that story. OK. OK. I'm always impressed of just a few, a few chapters. And this and you are using one of the best machine world. One, this is a great machine and this model was in 2022 late 2022. And we are using it for simply left hand on the keyboard up all the measurement, right hand on the concentration, the image. And he got a good information of external and he's now looking for vertebral part. I OK. I think it's very new. I think it is very new to some other. I think I mostly if you try to move your hand maybe a little bit, always look at the vertebra. You, you have to go with three brothers and look at you. So if I with your hand, you hold your hand, that's, that's it. OK. And put the down, you can the big time. It it is. So otherwise the vertebral you vertebral anatomic anatomical. It's exactly below the common car, just maybe one or 1.5 centimeter. And the best thing you is to look this way. No, me. No, you can see it. It vertebral artery which is feels like two millimeter. There is no ST phenomena and he's going from to and this is a very thin patient and it's a great view. It's fantastic. Fantastic. OK. So uh we finish the scan for carotid, we can put all the steps for it. Uh There's nothing else to add. Oh, um, so uh thank you very much. Uh Wish you all the best. I hope it is of benefit. I hope you on the global app and telegram can read the shelters about it and see the lecture. Um And if you are watching online, you are eligible for the certificate, continuous professional education, professional development CPD and it is with Doctor Mohamed and it will be signed by professor and you are eligible after a quick exam that we will do it next week on Sunday at 8 p.m. If you pass the exam. Congratulations, you get your certificate and you can start your career in the next day. I wish you all the best.