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ABSITE Review: Vascular, Part 1 (Podcast)
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ABSITE Review: Vascular, Part 1 (Podcast)
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>> Okay. And welcome back to another Behind the Knife ABSITE Review. Today we're going to do vascular. I'm here today with Jason Bingham, John McClellan, and myself, Keven Kniery. We did a vascular last year with Dr. Nathan Aronson. And that is a very good comprehensive discussion of vascular topics. This piece is going to have some overlap with that but it is going to be more of the kind of quick hits that you need to know for the ABSITE. So you should definitely listen to that one before you listen to this one. And this will likely be in two parts.
One thing I want to remind you guys, one tip for the ABSITE is make sure you go back and look at your old ABSITE score sheets to see what you struggled in the year previous. And I always spend my last week of the ABSITE season studying what I struggled on the year prior. Also, if you haven't subscribed to the podcast, please subscribe. It really helps us out and sign up for a mailing list. You can see that in show notes. Alright, let's dive in to vascular ABSITE. Alright, So we're just going to start with some carotid and vertebral anatomy.
So John, can you just tell me the basics of the anatomy of the vertebral artery? >> Yes, the vertebral artery is divided into four different segments. When you think of V1, it originates off the subclavian. And this continues to the foramina of C6. V2 is the foraminal part of the vertebral artery and this is from the transverse foramen of C6 to C2. And V3 is the -- continues from C2 to the dura. And V4 is considered intracranial.
>> Right. And so what I think the important part of knowing the vertebral artery anatomy is which parts are surgically accessible. And that's going to be V1 is surgically accessible coming off the subclavian. It's right off the proximal subclavian is where it comes off and that's where surgeons can intervene. The rest of it is going to be -- if it is going to need intervention, it's going to be by interventional radiology or vascular surgery through an intravascular method. And so, blunt injury, you want to think about blunt cervical spine injury, you want to rule out vertebral artery injury.
Okay. We talk about this a little bit last year but let's just briefly review it because it's on there so much. Jason, external versus internal carotid, which one has forward flow, which one has triphasic flow. >> Okay. So you're internal carotid is going to have your continuous forward flow. And for me that's easy to -- easier to remember when you think about -- what the internal carotid supplies. So that's really perfusion in your brain. So you're going to want that to have continuous forward flow.
Where the external carotid is going to have a triphasic flow and it has a higher resistance. So it's important to remember that if you have significant facial trauma and you're bleeding a lot, you can always just tie off the external carotid to minimize the bleeding with really minimal sequela. So internal carotid, continuous flow. External carotid, triphasic flow. >> Great. And then, so John, you're on vascular right now. Can you just tell us your basic approach to the carotid artery?
>> Yes. So the first step in exposing the carotid artery, and this is going to vary between surgeons, but the first few steps are pretty similar. So you want to make your incision anterior to the sternocleidomastoid. You dissect out the subcutaneous tissue and divide the platysma. Once you're [inaudible] the platysma, your first vessel you'll come by the is the internal jugular vein. At this point, you want to take the internal jugular vein and retract it laterally. At this point, you'll encounter your facial vein and you want to ligate the facial vein, it's your gateway to the carotid sheath.
And then you'll encounter your encounter sheath. From this point, you want to open the carotid sheath and then you would have your exposure, your bifurcation in your internal and external carotid artery. >> Great. So key point there, facial vein overlies the carotid bifurcation and you're always going to divide that in order to expose your carotid. So, Jason, what nerve lies in the carotid sheath? >> That would be your vagus nerve. >> And what do you worry about if you damage that? >> So, generally you'll get -- the deficits will be as a result of damage to the recurrent laryngeal nerve, so that would be hoarseness.
>> Right. And just a quick review from previous episodes. Can you tell me the course of the right versus the left recurrent laryngeal nerve? >> So the right recurrent laryngeal nerve courses around the subclavian artery, the left courses around the arch of the aorta. >> Great. Okay, John, we'll just cover a few more nerves. What nerve do you see right above the bifurcation? >> This would the hypoglossal nerve and then if you would happen to injury this during a CEA or something, you would get tongue deviation to the ipsilateral side.
>> Okay. And we have a high lesion and we're trying to get all the plaque out and we have the intern pulling hard on the retractor up under the mandible. What injury are we worried about then? >> So that would be damage to the marginal mandibular nerve. >> Right. And you'd get the drooping, which can be concerning postoperatively for a stroke, but a lot of times can just be a stunning of this nerve. Alright, John, where do you see carotid atherosclerosis and why is it there?
>> So if you're looking at duplex, the most typical part is the -- or portion is the carotid bifurcation due to the turbulence there. And if you would have, you know, atherosclerosis here, you could -- it could result in an emboli and it doesn't usually thrombose. >> Right. So the important thing is that the you'll see, you'll open a carotid artery, if you haven't done it yet, if you're an intern or something, all the disease is localized right at that bifurcation for the most part. And the way carotid disease in strokes happen, is not from a thrombosis of your carotid artery, but emboli coming from these plaques at the bifurcation.
So it's important to know that. Alright, John, and one more simple thing. When you're doing a carotid endarterectomy, what parts of the carotid are you removing? >> So you remove the intima and then a portion of the media, as well. >> Okay. Let's dive into the surgery part of it. Jason, you have a patient that has a stroke, have a -- what amount of carotid disease do they need to have that you will operate on it? >> So it's a little bit controversial, especially for the boards. The way I think about it is if the patient is symptomatic, in other words, they're having TIA, or having strokes on that side of the lesion, anything greater than 50 percent, I would say would be an indication for surgical intervention.
>> Great. And then, you know, what are you going to answer on your boards as far as asymptomatic disease. >> So asymptomatic disease, the cut off for me is probably going to be around 80 percent. Certainly, those patients -- everybody with carotid plaques or carotid stenosis need medical management with aspirins and statin. But as I mentioned, it's a little bit controversial but for the boards over 80 percent I'm going to operate. >> Great. So takes aways, if they have symptomatic disease, so if they have a stroke on the side of a carotid stenosis, it has to be over 50 percent for you to operate on it.
Asymptomatic disease has to be much higher, 80 to 90 percent before you'd operate on an asymptomatic patient. So, John, sometimes we won't get so lucky. They're not just going to tell us what the percent stenosis is and they might just give us ultrasound findings. So what would you look for in ultrasound to correlate with symptomatic disease, that you would operate on? >> Yes. Typically, in these questions, it will give you -- it won't be a borderline type of velocity.
They'll give you something of a severe disease, like greater than 70 percent. And these typically have velocities greater than 230 centimeters a second. >> Yes. And Jason, so I've seen some questions and they love asking these and a patient had a right-sided stroke and they have left-sided symptoms, and then they give you -- they do the carotid duplex and they have 40 percent stenosis on that side. What do you want to do? >> Less than 50 percent I'm going to manage medically and not operate. >> Exactly.
Okay, John, another scenario that they like to bring up a lot. A patient has a stroke and you do your duplex and the carotid is completely occluded on that side. What would you like to do? >> So in this situation anticoagulation would be your first step, just to prevent propagation. These typically don't [inaudible]. >> Right. And so there is no indication for surgery, at least on the ABSITE and they completely occluded carotid. You're going to put these patients on anticoagulation?
I remember, you know, before as an early intern in second year being amazed by this. Why don't you want to open up? But you can actually cause reperfusion injuries and cause worse problems. And we're going to talk about that a little bit more in our trauma portion of this. So, Jason, not many emergent indications to operate on a carotid but what are some things that would make you operate sooner rather than later. >> So I think it would be the patients that present with evolving strokes symptoms or so -- like fluctuating and neurologic symptoms or your, you know, crescendo or evolving TIAs.
>> Great. So, John, as far as the way you're going to repair a carotid, what are the two techniques that are commonly used. >> So the two techniques, typically the patch angioplasty or the aversion technique. >> Right. And then, what if they say, you know, the ends come together well and it doesn't appear that there needs to be a patch and they just want to, you know, they're kind of hinting at primary closure of the carotid endarterectomy on the tests. Are you going to accept that answer? >> No. Always patch.
>> Yes. The patch has much better long-term patency rate. So you definitely want to do a patch. You do not want a primary closure. And we talked about this a lot. Any vascular patient that has atherosclerotic disease, what is their -- especially after carotid, what is the most common cause of non-stroke mortality after carotid endarterectomy? >> MI is the most common. >> Okay. And so, Jason, you're operating on your carotid, you're peeling at that plaque, and the patient suddenly becomes bradycardic and hypotensive.
What do you want to do? >> It's probably because I've manipulated the carotid bulb and I was dissecting a little too close into that carotid bifurcation and stimulating that. So what I would like to do -- or ways you can avoid this is by injecting lidocaine into the carotid bulb to blunt the vagal response of the baroreceptors in the carotid sinus. >> Right. And I don't think this next question would be [inaudible] pertinent, but sometimes they may get picky and ask carotid sinus versus carotid body. And so carotid sinus is what is irritated and has the vagal response that causes the hypotension.
The carotid body has actually O2 sensors. I remember that because body with the O, O2 sensors. So it's actually the carotid sinus that causes the vagal response. Okay, John, so, they may give you a patient that has had a stroke and they ask you when do you want to operate on this patient? Can you give us, sort of, your kind of breakdown? >> So you can divide it into three different parts, small, moderate, and hemorrhagic stroke. A small stroke are just the simple TIA. You want to typically operate within two weeks once the symptom resolved.
And it only occurs if you have less than 200 grams of brain affected on an MRI. In a moderate stroke, you want to usually operate in four to six weeks. And a hemorrhagic stroke, extend it out a little further, at six to eight weeks. >> Right. And so the idea is, you're trying to prevent turning ischemic strokes into hemorrhagic strokes. And the pendulum is swinging a little more towards operating early but for the ABSITE, I think it's safe to say, if they've had a moderate stroke, you can wait about a month and then operate and that will be safe.
If they've had just a small stroke or a TIA, they're now saying do it sooner rather than later. So do it within two weeks. And if they've had a hemorrhagic stroke, you probably want to wait two months before operating. So, Jason, dreaded scenario. You're in the PACU and your patient has right-sided hemiplegia and they didn't have that previous. What do you want to do?
>> I'm assuming this is after my carotid endarterectomy, not after my umbilical hernia repair. [Laughs]. >> Yes. [Laughs]. >> Okay. So if the patient is in the PACU, and they have neurologic symptoms after a carotid endarterectomy, on the tests especially, I'm taking those patients back to the O.R. for exploration. >> Right. And so you're going to evaluate for any intimal flaps or thrombus. And a lot of times you'll start in the O.R. looking with ultrasound but you're going to -- on the test, that patient that has a new hemiplegia post operatively, you're going straight back to the operating room, even within 24 hours.
So, John, it's always a common question, more common on board -- on rounds than on -- or in the operating room than on the ABSITE, but what orders do you want to clamp the vessels during a carotid endarterectomy and why is this? >> Yes. You can remember this with the ICE pneumonic, which is internal, common, and then external. >> Right. And so the reason that is that the -- you want the internals, obviously, is what feeds the brain. So you clamp that first before manipulating the other branches. And then, John, what order to you release them in?
>> The reverse order. So then you would go external, common, and then internal. >> Right. And hoping to flush any sort of plaque or thrombi out the external and not into internal. So, Jason, kind of, when do you consider using carotid stenting versus carotid endarterectomy? >> That's a tough one. I think -- most people are going to try to get them to carotid endarterectomy.
But patients who really can't tolerate anesthesia, so they're very -- very poor surgical candidate or patients through a combination of comorbidities, which you anticipate to be a difficult surgery if they've had a neck -- prior neck dissection, neck radiation, or recurrent disease. I think I would consider for a carotid stent. >> Exactly. Now, John, if this patient has had a previous thyroidectomy. So now they've neck surgery, you know, that makes me a little nervous about performing a carotid.
Is that a contraindication for performing a carotid? >> No. There is a relative contraindication if they potentially had recurrent laryngeal nerve damage in the first operation. But the answer would be no. >> Great. Great. Okay, so now we're going to go into trauma and carotids. Everyone loves trauma and carotid disease. Jason, could you just break down the biffl classification that sometimes can come up? >> Yes. So the biffl grading system is grades 1 through 5.
So grade 1 is just an intimal irregularity with less than 25 percent narrowing. Grade 2, dissection or intramural hematuria with greater than 25 percent narrowing. Type grade 3 is a pseudoaneurysm. Grade 4 is a occlusion. And grade 5 is transection or if there's any extravagation. >> Yes. And just as a disclaimer here, I went and looked at the most recent guidelines. And there actually are no good quality studies on most of these. There is no level one evidence. There's really no level two evidence.
All the evidence discussion traumatic carotid injury is really about level 3. So, you know, I don't think there's a whole lot they can ask about it but here we'll ask a few questions that I think are appropriate for ABSITE. So, John, you have blunt trauma and the patient is found to have carotid dissection on imaging. But they have no symptoms. It was found on your CTA. >> Yes. You would find most vascular surgeons or sometimes neurosurgeons will be for the intracranial portion of vertebral artery will actually be consulted for this.
The majority of the time they actually recommend aspirin therapy, 325. In some situations, they -- if a patient can't tolerate aspirin or has a contraindication to aspirin, then they would recommend anticoagulation, usually with heparin or Lovenox. >> Great. And now, Jason, you have a patient that has a carotid dissection identified and they also have some neurologic findings associated with that. >> So if they have a blunt trauma and neuro symptoms, that's the patient I'm going to want to endovascular intervention and a covered stent.
>> Great. And then, John, to close it out here. You have a patient that has a completed stroke. They come in, they had some kind of neck trauma, CTA shows a thrombose carotid on that side. And you know, they have a dense hemiplegia on one side. What are you going to do for this patient? >> So I would not operate on this patient. They unlikely to usually get better with interventions. They usually get antithrombic therapy.
>> Right. So, just kind of -- you know, this is a little controversial and I've seen questions in score. So if a patient maybe has -- presents and they have evolving neurologic symptoms or, like, you know, essentially thrombosed in front of you or in the operating room, something to that extent, you could potentially recanalize the vessel, but if a patient has a completed stroke or has dense hemiplegia, operating is only going to cause problems. So on the test, I would -- a traumatic carotid thrombosis, I would not operate on unless they give you indications that this is a disease that is still in evolution and that you can potentially improve upon.
But most of these patients are not going to get better and just want to do antithrombotic therapy, either antiplatelet or heparin. And then, John, there's always some questions on the carotid body tumors. We're not going to get too deep into here. But what are the basic principles of managing carotid body tumors. >> The easiest answer is just to look for the answer of choice that gives you -- or the answer of choices that give you option for resection. And then you can also consider embolization prior to surgery. But I have yet to see that on a test.
>> Right. So sometimes I've seen, they'll give you patients that are completely asymptomatic and just has a little lump, et cetera. These patients still need their carotid body resected. And then if it's a very large lesion, you can consider embolization prior. >> And don't be [inaudible]. Sometimes they'll give you the options for biopsy, like a core needle biopsy. Don't -- don't do core needle biopsy of this. >> Yes. The characteristics are -- on imagining are to find the lesion. So, okay. Guaranteed 100 percent and we talked about this is a podcast or two before this to have this question.
Jason, take us through the basic anatomy of the thoracic outlet. >> Yes. So you'll some variance of this -- they'll ask you, you know, they'll give you the scalenes, the subclavian artery, veins, nerves, they'll ask you to order them from anterior to posterior, posterior to anterior. So just know these. So anterior to posterior in thoracic outlet, you have your subclavian vein, your phrenic nerve, which lies on top of your anterior scalene, behind your scalene you have your subclavian artery, your middle scalene and then your first rib.
>> Great. And we'll dive a little bit more into this in a second. And then, John, what, you know, puts a patient at risk for thoracic outlet syndrome? >> So they have an extra cervical rib, is usually the most risk. >> And there's one thing that we didn't mention in that anatomy outline, where John, do you see the brachial plexus -- where is the brachial plexus in that anatomy, there? >> The brachial plexus runs along the middle scalene. It's posterior to -- just sort of remember, it's posterior to the subclavian artery. >> Yes. Okay. Now, we're going to talk about -- now we know the thoracic outlet anatomy, let's talk about problems with thoracic -- I feel like this is moderately high yield.
So, Jason, tell us what the most common type of thoracic outlet syndrome is. >> So the vast majority are going to be neurogenic thoracic outlet syndrome. This is about 95 percent of them. So these are symptoms which involve the ulnar nerve distributions, ring and pinky fingers, and the symptoms are worse with manipulation. >> And what are you going to offer these patients? >> So for neurologic, first step is going to be physical therapy. Definitely physical therapy. >> Right. And then, hey, I've been doing three months of physical therapy, every time I lift my arm to put boxes up on the Amazon warehouse shelf, my -- I get tingling in my hand.
I can't handle this. >> So first thing I would do is nerve conduction studies that confirms there are neurogenic thoracic outlet syndrome. And then if confirmed and they failed non-operative management, you can operate by removing the first rib and scalenectomy. >> Yes. Very important to know that. So neurogenic symptoms, physical therapy first. And then if they fail and they have it proved on a nerve conduction study, you can offer them a first rib resection and scalenectomy.
Okay. John, seen this once. A guy comes in, he's generally a weight lifter, maybe a swimmer, maybe a pitcher. Comes in with a swollen, blue arm. What is this? >> So this would be a subclavian vein thrombosis or Paget-Schroetter disease. >> And how are you going to diagnose this and then how are you going to fix this? >> So your first step should be a duplex or a venography. Duplex would probably be the answer on a test. And then this is important to remember, that during the order of operations for fixing this is that you want to first go catheter-directed thrombolysis to get that clot out of there.
It's kind of an emergent procedure. And then it would be followed by first rib resection in the same hospitalization. >> Yes. I think that's very important, is they're going to -- you want a thrombolyse it. Place a thrombolysis catheter and open that vein up. And then within that same hospital stay, you're going to do the first rib resection to prevent this from happening again. >> It's a very common question. You're going to get that. Clinical core [inaudible].
They're going to give you thrombolysis alone. Thrombolysis with rib resection at some interval or thrombolysis with surgery during that hospitalization. And that's going to be the answer. >> And then just briefly, arterial. Very rare to have arterial thoracic outlet syndrome. But this would be a patient that presents with ischemic signs in their hand. They have, you know, "cold arm." So, obviously, this is an emergent indication to revascularize the arm.
And this can be -- you can do either a thrombectomy from the brachial artery. But a lot of times the artery will be permanently damaged and you'll need to do an interposition graft with resection of the first rib. Okay. John, real quick. Subclavian steal syndrome. We talked about it a lot. What causes subclavian steal syndrome? >> Yes. This is a proximal subclavian narrowing, which then results in a reversal of blood flow through the ipsilateral vertebral, which then could lead to your vertebrobasilar symptoms.
>> Yes. And so, if you haven't seen this or seen an animation of this or something, please, just Google it. It really helps. It's hard to hear it and understand it. But, John, how are you going to fix this? >> So I've only seen it as a -- they give it as a carotid subclavian bypass or a subclavian transposition. But there's -- you know, in the world of endovascular repair we can also talk about endovascular recanalization and or stenting.
>> Right. So, exactly. So you need to, you know, one way or another open up the subclavian. In the past they used to do subclavian endarterectomy but that ended up being too morbid. So now the more common answer is the carotid subclavian bypass. I don't think they're going to give you the option between subcarotid -- subclavian bypass and endovascular repair. It will be one or the other. But one way or another, you need to fix the occlusion of the proximal subclavian artery.
Okay. We talk about dialysis access, a significant amount in the first one -- our first vascular podcast last year. We're just going to talk about a few things. I've seen a lot of questions recently about catheter management. Jason, has seen questions a lot about peritoneal dialysis, which we're actually going to talk about in a later podcast. In regards to catheters, Jason, can you talk about just what are the options of catheters and if you are placing a temporary catheter, you have a patient that you operated on that went into acute renal failure.
What's the amount of time you want to leave a temporary catheter in? >> Sure, so if we're talking about just catheters -- and before we talk about other forms of dialysis access, there are temporary and there are long-term dialysis catheters. So your temporary catheters are really designed to be left in three weeks or less. Then you have long-term catheters, which differ in the fact that they are double lumen, they're cuffed, they're tunneled. So they can really be maintained for a longer time period.
>> Right. So the temporary catheters are the ones that are in the ICU, they're generally the Mahurkars. I'm sure many of you have placed. The tunneled catheters are generally placed by intervention radiology and like Jason said, they're cuffed, they're tunneled, they're double lumen. And they can last much longer. So, John, you're IR, you got a new IR doc there, something. They say where do you want us to place this long-term catheter? >> So your first go-to -- and they give you this question, should be your right IJ.
So it gives you direct access to the right atrium. >> Right. This is an important question to not just blow off. So, Jason, when you're thinking about this what else are you thinking about other than the right atrium as far as placing dialysis -- temporary dialysis access. So you want to think about what your future, like, permanent access is going to be. So think about hands dominance, where you plan on doing your procedure. What you really want to avoid is central venous stenosis on the side where you plan on doing your fistula.
>> Great. And we talked about the fistula first and some managing that in the first podcast. So please refer to that to learn a little bit more about that. John, fasciotomy is a common question. Probably one point on the ABSITE here. Tell me where you make your -- so, we're talking about lower extremity fasciotomies for compartment syndrome. Where do you make your incisions? >> To make -- to access the anterior and lateral compartment, you'd make an incision lateral to tibia, about halfway between the tibia and fibula.
This can be an H-type incision or just a big longitudal incisions. And this would help you access your anterior and lateral compartments. >> Right. And to be clear the H-type incision is on the fascia once you've opened. So you'll have a single skin incision, make it as long as possible. And then you want to fully open the anterior and lateral compartments, you do the H-type. A lot of times people can leave the H -- I'm sorry, the anterior compartment not fully decompressed and actually put just the incisions on the lateral compartment because it's such a large compartment.
So, John, with the lateral incision, what nerve do you worry about injuring? >> Yes. I've seen this question a few times. The superficial peroneal nerve. And you -- they would present a patient who has difficulties with foot aversion. >> And what part of the leg is that? Is that going to be the distal part of the incision or where are you going to injure that nerve at? >> It's typically more proximal. >> Right. Near the fibular head is where you're going to see that nerve and you have to be careful.
And so, Jason, so now you've already made your incision, you've opened up your anterior and lateral compartments with your lateral incision, now you're doing your medial incision. Where are you going to make this incision, in what compartments are you opening with this? >> So for this you want to make an incision 2 centimeters or a couple finger breadths posterior to the medial tibia. So you want to make sure that the deep posterior compartment has been fully decompressed. So both the superficial and the deep posterior compartments are decompressed through the medial incision.
The way you do this, the way you get to the deep posterior compartment is by being sure you take the soleus off the back of the tibia. >> Right. And it's kind of a brute maneuver, kind of tearing that soleus off the tibia. But that is one of the most commonly missed compartments. So it's very important to do that. We'll talk a little bit more about the contents of the compartments a little bit later here. So just real briefly, John, we're going to go through thoracic aorta. Just a few questions I've seen on this. With blunt thoracic injury, where do you see the injury?
>> Because the aorta is tethered at the ligamentum arteriosum, you'd typically see an injury there, such as a pseudoaneurysm. >> Right. And this is generally just distal to left subclavian artery and this is where you're going to find those big pseudoaneurysms in patients with blunt thoracic injury. And if they have a total transection at this point, they're obviously not going to make it to the hospital. So most of the time, you're going to see patients with pseudoaneurysms here. Jason, briefly, descending aortic aneurysms.
You know, ascending aortic aneurysms isn't -- they're about the same criteria but that's managed more on the cardiac thoracic side of the house. But on the descending aortic aneurysms distal to left subclavian, what are your criteria for repairing aneurysms? >> So typically the cutoff is 5.5. And those are for your descending thoracic aneurysms that are amenable to TVAR and vascular repair. If for other reason you can't -- they're not amenable to endovascular repair, the cutoff is a little bit higher, so around 6.5. >> Yes. So like we've discussed, you want to worry about paraplegia, about a 5 percent risk of endovascular -- for endovascular repair versus 20 percent for open.
So these can be very morbid procedures. But, you know, it's an important thing to fix if you do have it. So if you do and Dr. Aronson, talks about in the first episode, if you're going to have a stent cover T8 to L1, this gives them the highest risk of paraplegia. So if it's in that area you want to make sure you are placing a lumbar drain due to the high risk of paraplegia. Okay. Next topic. We're going to talk about the abdomen. Back to where we're a little more comfortable here.
Acute mesenteric ischemia. Very common topic. Guaranteed to have a question on this. If you probably this and carotid disease would be the two questions you get on the ABSITE as far as vascular disease goes. So, John, what are the four types, just briefly? >> Yes. So embolic, thrombotic, and venous thrombosis, and then you have your NOMI, or nonocclusive mesenteric ischemia. >> Right. And we're going to spend most of our time talking about the embolic and thrombotic versions of this.
So the embolic is the most common. They likely have atrial fibrillation or endocarditis. And then they develop acute, sudden abdominal pain out of proportion to exam. The thing here is that a lot of these patients have embolic disease. They don't really have the history of chronic vascular disease, weight loss, et cetera. They generally were doing fine and all of a sudden have abdominal pain. That's going to queue off to the embolic disease. So, Jason, tell me how you diagnose this and how you approach this. >> So you know, first you -- as you said, you're going to be worried about patients who come in, who -- they're going to give you a history of a-fib, they're going to have horrible abdominal pain.
It's going to be characteristic out of proportion to physical exam. My first key -- my first step to diagnose this is going to be a CTA if that's an option on the test. >> Great. And they say, what is your next step in this patient? The radiology calls you and says, yes, there's a embolus in the mid SMA and you're spinning up the O.R. What do you want to do? >> Yes. So this is key. That next is going to be to heparinize that the patient.
>> Right. Jason, one other thing. Can you talk about the distribution of the disease in a thrombotic versus embolic SMA thrombosis? >> Yes. So thrombotic is going to be effects more proximal on the SMA. So it's really go to effect the ostium. So these are people that are going to have long-standing vascular disease. It's going to be more insidious in onset. Whereas, your embolic disease is going to be very, very acute.
It's going to be more distal on the SMA. And for that reason you have kind of a characteristic jejunal sparing of the ischemic disease in the bowel. >> Great. Exactly. An SMA embolus, the patient has a-fib. It'll lodge [inaudible] distal in SMA and you'll have some proximal jejunal sparing. Whereas, thrombosis, you'll just have your entire small bowel ischemic. So John, how do you identify your SMA in the operating room? >> Yes. I had this question on oral boards last time.
So you want to go in, you lift the transverse colon, [inaudible] and you just follow the base of the transverse mesocolon and down until you find the ligament of Treitz. And the SMA will be lying right of that. And if you need to get to the SMA origin, then you can mobilize the ligament Treitz. >> Right. And so I think this is definitely the correct answer for the ABSITE. You can also access the origin of the SMA, especially if you're going to do an SMA bypass by doing a Mattox maneuver. But for an embolus, you're really going to want to get to the mid portion of the SMA.
And this is a much better approach to it by lifting the transverse colon. Okay. So now we know, SMA embolus. You're going to make a transverse incision in the SMA. You're going to use a Fogarty catheter to remove the clot. And then you'll close your arteriotomy. And once that is complete, that is when -- and you reperfuse the bowel you'll give it 20 minutes, warm lap pads over the bowel, and reassess the bowel at that point to determine which bowel needs to be resected.
So I've seen questions on that where they say do you, you know, dusky bowel throughout the entire abdomen. Do you want to resect? And then restore perfusion. Do you want to restore perfusion first hand and then reevaluate the bowel after that? So, Jason, what if, you know, the bowel is -- you've restored, you did a great embolectomy. Some of the bowel is still questionable. And the patient is a little sick. What do you want to do?
>> So this is where, like I say, be sure you restore blood flow and the reevaluate. So you can see if it pinks up, you can use your adjuncts, like your intraoperative Doppler, you can use your [inaudible] lab with your florisene, some of the newer technologies, like SPI, and all those things. You can take a look at the bowel. Anything is [inaudible] is dead. I mean you resect that, certainly. Anything that is questionable or not sure about, there is nothing wrong with leaving the abdomen open, go into the ICU, resuscitating, coming back within 24 hours for your second look laparotomy.
>> Great. Exactly. So any question about in a lot of this patients, you're going to leave the abdomen open and you're going to reevaluate in 12 to 24 hours. So I think that will definitely be the answer on the test is to leave the abdomen open and reevaluate. One thing I didn't talk about is quite the therapy of treating thrombotic disease, not as ABSITE pertinent but thrombotic disease is where you know they have this chronic vascular disease, their celiac access is likely to be diseased.
Their SMA is heavily diseased. Their aorta throughout is diseased. These are the patients you're going to consider doing bypass grafts, whether it's a iliac retrograde bypass to the celiac and SMA or a supercilia bypass to the celiac and SMA. But generally, you're likely going to bypass both the celiac and SMA in most of these patients because it is a generalized disease process. Not a focal embolus, like you have in embolic disease. So just a quick point on that in case it does come up on your test.
John, one other one that comes up is mesenteric venous thrombosis. What do you see in these patients? >> These are the patients that have less of an acute process and won't have that sudden onset pain. They'll have days of abdominal pain, possibly bloody diarrhea, history of bloating. Some patients will also have history of weight loss and they usually will generally have some underlying hypercoagulable state as well. There's something in their history they'll tell you.
>> Great. And what will you see on CT scan? >> So you'll see diffused bowel wall thickening, mesenteric edema, possible thrombosis to the SMV and delayed filling of the portal vein. >> Alright. And are you calling the O.R. to rush them back when you get this -- when radiology calls you with this diagnosis? >> No, not unless there's obvious signs of dead bowel. Newer peritoneum, extreme edema, free fluid. You just heparinize these patients and don't use thrombotic -- or thrombolytic, excuse me.
>> Right. So mesenteric venous thrombosis, you're going to attempt heparinize these patients. And a lot of these patients will be able to recanalize and will improve. But, obviously, these are critically ill patients. They'll be observing in the ICU, serial abdominal exams and a heparin drip. And making sure that they do not get worse. Okay. So we've covered embolic disease. We covered thrombotic disease. Those are the ones you're going to get questions on.
Then you have the mesenteric venous disease, which is a little less common and less pertinent. Jason, quickly, NOMI. What is NOMI and what patients do you see this in? >> So NOMI or nonocclusive mesenteric ischemia effects your extremely ill, ICU patient, multiple pressures, abdominal -- they develop abdominal pain and distention, a lot of times you'll see it in patients who have cardiac failure, but really can be seen in any patients with shock or have, you know, poor forward flow.
It's going to affect your watershed area. So you're Griffiths and Sudeck's point, at the splenic flexure or the upper rectum. Specifically, on the boards, the answer is not typically going to be an operation unless they have, you know, frank perforation, necrosis that needs to be addressed. But it's going to be resuscitation, potentially dobutamine, specifically if it's cardiac failures is the underlying etiology and antibiotics. The overall goal is to improve your forward flow or improve your cardiac output.
As I said, the only indications for operating on these patients is going to be frank necrosis. >> Yes. You're in a rock and a hard place when you get consults on these patients. So definitely attempt not to operate on these patients, improve their flow. That does it for vascular part one of 2018. John, before we end we have to do our quick hits. So what is the most common site of an upper extremity embolus to lodge? >> Yes. Typically it's the brachial artery.
You're going to want to pick more distally, but it is the brachial artery. >> Right. And Jason, how about for the lower extremity. The patient has a-fib, they throw off an embolus. Where is it most likely to lodge? >> So it's going to be your CFA or common femoral artery, usually right at the bifurcation. >> Right. And so this is when you have acute changes in the diameter of vessels is where these emboli are going to lodge. Okay. John, a patient with a ruptured AAA with hypotension is getting crash laparotomy.
Where should you get proximal control? >> So the supraceliac aorta and you want to go through the gastric hepatic ligament underneath the [inaudible] of the diaphragm. And you want to press the aorta directly on the spine until you can get aortic clamp on. >> Great. Jason, a patient -- you're at the major medical center in town and there is a, you know, rupturing AAA. The patient is moderately stable. They don't have a vascular surgeon in house. And they're transferring him to you.
What do you tell the -- they say, what would you like us to do as far as his blood pressure goes in transfer? What are you going to tell the transfer center? >> So this is analogous to what we see to our trauma patients. Well, us military members would overseas, but we want to do the permissive hypotension. So you don't need to resuscitate these patients to a normal blood pressure. You want to maintain them at a systolic blood pressure around 80 to 100. >> Great. And then John, what's the most common organism in graft infection?
>> Yes. Steph epidermis, which is usually just present on your skin. >> Great. And then Jason. Treatment for popliteal entrapment syndrome? >> So popliteal entrapment syndrome is treated by resecting the medial head of the gastroc.