Peripheral Arterial Disease: Diagnosis and Treatment

by Carlo Raj, MD

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    00:01 Clinical history. The setting of the risk factors to be exactly as to what we talked about earlier about the coronary arterial disease and we will look into that in a little bit.

    00:11 Non-invasive testing. This will be the first time in which we'll not use a EKG, obviously here, makes no sense. We are not in the heart; we are down in the periphery.

    00:21 What kind of non-invasive test, how important is this? really important because the more you are able to come up with non-invasive testing and it being efficient and effective, the better of you be it every possible way. You will be respected by your peers and in terms of next step of management, any question that you get here it is. It's called ankle-brachial index and that is the one that we will pay attention to. There are a couple of others that you may do as well but at least, get this one done. Once you have understood ABI, ankle/brachial/index in other words, you are going to measure the pressure in the ankle, you are going to measure the pressure in the brachial upper extremity. Are you there? And you are going to do a ratio. When you do that ratio, you will get a particular number and this is what I would like you to understand.

    01:17 It is too much to memorize. What I would like for you to do is to think about what exactly is happening with the pressures in the two extremities. And what can you expect with the ratio. And once you do that, you will be much better than we were. Ladies and gentlement, we will be doing this, we have been doing this for every single organ system from like B1 creatine ratio to tubular fluid to plasma ratio in nephrology, you name it. Every type of ratio that we have done, has been the fact that it is all about understanding, and what you can expect normally so that you can then identify the abnormal. Take a look at this. So we are going to do, either right or left and we will put both up here and ankle A, then brachial. Do it alphabetical order. The ankle will be on top and the brachial B will be the denominator. That would mean ankle and then you have your brachial in your arm.

    02:21 What do I mean by higher? Clinically speaking you will measure the ankle pressure of both of the legs, right and left and you will take the higher one. Then you will have the brachial. Once again you will measure both and you will take the higher one.

    02:37 On the other side, and then you will do the ratio. Once you get the ratio, now you tell me where do you expect there to be the higher pressure, the ankle or the brachial? Take your time. Ankle. So, when we do the ratio in a little bit, we are going to find where you can have your upper normal limit of that ratio being above 1. Now we are going into technicalities and details, why are we doing this? Because we are going to identify noninvasively whether or not your patient is suffering from peripheral arterial disease. Use common sense now. If there is peripheral arterial disease, am I supplying adequate amounts of blood down to the dorsalis pedis? Of course not, so what would you expect that pulse and the pressure to be? Decreased. Are we clear? So let us move on. Let us confirm this. You measure your ABI. Interpretation of it.

    03:42 Abnormal, absent pedal pulses. You can feel it. Age within 20 and you find that your patient has a history of smoking, diabetes mellitus. Let us get it confirmed just non-invasively. You find your ABI, ankle-brachial index to be less than 0.9 please know that you have confirmed diagnostic of peripheral arterial disease. This is the one that you pay attention to first and foremost, please. As I fill in the gaps a little bit more this will be good information for you to keep in mind. I'll give you normal, what that means when you have excess. Right now let us just keep our task and our task at hand is to confirm non-invasively peripheral arterial disease. We are using ABI, ankle-brachial index. And so therefore, we said and you will agree that the ankle pressure should be higher than the brachial. And if you find the peripheral arterial disease that the ankle pressure is quite low, then what can you expect that ratio to be? Work with the concept first, a low ratio.

    04:57 Once you find a low ratio, what have you done? You confirmed PAD. What exactly is that number? Less than 0.9. Then you memorize the number, you do that every single time. Well the fraction excretion of sodium, later on in nephrology. You understand the concept first and then you memorize your numbers, if you must. The concept will never leave you. Here is another one. This is normal. Between 0.9 and it can go all the way up to 1.3. The ankle pressure is a little bit higher so therefore, this is normal, no further testing required. What if you find your ankle to brachial index to be greater than 1.3? Then your next step of management is your Doppler. And so now you start to think about the ultrasound and such. Duplex, Doppler.

    05:43 There is something else called toe pressure. Just keep these in mind as your next step of management if you find your ABI to be greater than 1.3. Let us then take a look, we confirmed PAD. Now, if it is greater than 1.3 and you found this to be confirmed with a Doppler waveform, then you start thinking about diabetes mellitus and even end-stage renal disease may have falsely elevated levels. Renal failure. In nephrology we have talked about quite a bit about with end stage renal disease and there often times you find your blood pressure to be quite high, don’t you? Why? Because you don’t have proper GFR. And so if your GFR dropped then you are going to build up volume, welcome to hypertension. So, you might have falsely elevated levels with ESRD, end-stage renal disease. At this point, your focus should be peripheral arterial disease and how you could confirm that? By having a low ratio. Let's move on.

    06:45 Modifiable risk factors. These are the same ones that we saw earlier where then we talked about atherosclerotic disease. This includes, if you can try, to implement, smoking cessation programmes, blood glucose levels for diabetes. The treatment of dyslipidemia, statins, where is the other one of the statin which is now current day practice proven to be incredibly effective, called proprotein convertase PC subtilisin S, kexin 9 inhibitor and those are your either alirocumab or evolocumab, available now and decreases your LDL cholesterol up to 70 percent. We have treatment of hypertension. All these are modifiable risk factors include also antiplatelet therapy, aspirin, have the obstructive lesions bypassed surgically if need be, worst case scenario, talk about that diabetic who has peripheral arterial disease and diabetic neuropathy and there are enough necrosis and gangrene in which the only step of management next is to then conduct amputation and that's just unfortunate.

    About the Lecture

    The lecture Peripheral Arterial Disease: Diagnosis and Treatment by Carlo Raj, MD is from the course Arrhythmias.

    Included Quiz Questions

    1. ABI < 0.90
    2. ABI > 0.5
    3. ABI > 0.90
    4. ABI > 1.5
    5. 0.9 < ABI < 1.3
    1. Autoimmune vasculitis
    2. Smoking
    3. Hypertension
    4. Dyslipidemia
    5. Glucose control
    1. All are potential explanations
    2. Non-compressible calcified artery
    3. Testing error
    4. Diabetes mellitus
    5. End stage renal disease
    1. Posterior tibialis and brachial artery
    2. Most distal pulses are measured from the upper and lower extremities respectively
    3. Posterior tibialis and radial artery
    4. Dorsalis pedis and radial artery
    5. Dorsalis pedis and brachial artery

    Author of lecture Peripheral Arterial Disease: Diagnosis and Treatment

     Carlo Raj, MD

    Carlo Raj, MD

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