Vascular- Part 1(v2)

Okay. And welcome back to behind the knife ab site review. Now we're going to dive into vascular and it's Jason and Kevin. All right, Jason, let's just knock out some anatomy here to start. What are the structures of the carotid sheath? So you have the carotid artery, the internal jugular vein and the vagus nerve. Okay. And just briefly, what are the segments of the vertebral artery? Okay, so you have four segments. So V one which is the origin of the subclavian to the foramina of C six, and then the V two, which is the foraminal portion is from the transverse frame of C two to C six. It travels through C two to C six, and then B three is, from C2 to the dura, and then V4 is your intercranial segment. Yeah, so really only V1 is surgically accessible without endovascular methods. So what is the structure commonly overlies the carotid artery bifurcation? Yeah. So this is your gateway, right? So it's the facial vein off the IJ and it generally, like you say, overlies the bifurcation and is your gate to the

bifurcation. And so what is the first branch of the external carotid artery? First branch external carotid artery is your superior thyroid artery. Yeah. And this is a lot of times is the easiest way to differentiate the external from the internal carotid arteries. The external is going to immediately have branches coming off of it. It's also going to be more anterior. The internal is going to be a little more. posterior, but the internal does not have branches coming off. And that first branch is that superior thyroid artery. So does the external carotid artery have high or low resistance flow? So external carotid artery has high resistance. So, it flows to the muscular facial muscles. So it's triphasic on Doppler with a brief reversal of flow. Yeah. And so the way that's different is the internal carotid artery is, has a low resistance because you're constantly having forward flow to feed the brain. Yeah. I could see it being a problem to have reversal of flow through your internal carotid. So that makes sense. So can the external carotid artery be ligated? External carotid can be tied off to help control excessive facial bleeding in the setting of trauma.

Sure. All right. So let's dive into some complications after a carotid endodectomy. What if your patient has hoarseness after the case? So in that situation, I'd be worried that there was an injury to the vagus nerve during the case. Yeah, and so, what maneuver during the case can cause that injury? Well, we know it's in the carotid sheath, so from clamping of the carotid you can damage the vagus nerve if it was also clamped. Yes, it's important. The vagus runs posteriorly and is closely associated with the carotid to make sure you dissect that off, especially like in a trauma scenario where you're really moving fast. You can see how people could easily clamp the vagus nerve. So just be careful with that. All right. So what if you have tongue deviation to the side of the injury? So tongue deviation to the side of the injury, I'd be worried about a hypoclossal nerve injury. Great. And where would you find this nerve? So it's just cephalic to the carotid bifurcation so it can easily be damaged in this area. Okay. And so now the nurse calls you to the PACU and she

says the patient's having a stroke cause he's got a mouth droop on the side what are you concerned for here? Yeah. So, that marginal mandibular injury, which is pretty common, it's usually a retraction injury. Yep, and so that's from retraction on the mandible. Obviously, you don't totally dismiss this. You do a full kind of clinical exam on the patient to ensure that it's just the ipsilateral mouth droop. But yes, that's it. So this nerve lies deep to the posterior belly of the gastric and if it's divided can cause disabling dysphagia. Yeah, it's a glossopharyngeal. Right, and so You gotta worry about this when you're talking about a high dissection. If it's a really high lesion, sometimes in carotid aneurysms we don't normally divide the digastrics, we don't normally encounter this. But if it's a kind of a different case where you're dividing that posterior belly, the gastric, you definitely have to be careful with that. Alright, so what layers of the carotid are removed during a carotid ectomy? So that would be the intima and parts of the media. Yep. And so we're gonna cover this a handful of times here, but. Where is the most typical

location for atherosclerosis in the carotid? Yeah, at the bifurcation and it's related to turbulent flow. Exactly. All right. So, always very, very testable here. What are the basic indications for carotid endarterectomy in a symptomatic patient? Okay, so for a symptomatic patient, like a stroke or a TIA, if there's 50 percent stenosis, that would warrant surgery if there's no other identifiable cause of the stroke. Exactly. So they've had a stroke or a TIA. and have greater than 50 percent stenosis and you've ruled out other causes of stroke. Okay, great. So asymptomatic when you're retreating these patients. So it's somewhat controversial and I'm sure it's changed since the time that I took the upside. But if it's over 90 percent or if the end diastolic velocity, Is greater than 140 centimeters a sec, a seconds and a the patient has a longer life expectancy, right? Exactly. Yeah. It is a little bit

controversial in Europe. They don't even treat asymptomatic carotids at least in the UK. So really you want to make sure if you got this question, the answer would probably be best medical therapy, smoking cessation, aspirin, high dose statin, repeat imaging I think would probably be the best answer. For an asymptomatic. So a patient that has just found this on, a scan or something. But if there is a patient with a long life expectancy and a really tight lesion there is some benefit to a carotid endarterectomy with all that being said, score still says greater than 70 percent for asymptomatic you can treat on the exam, greater than 70 percent asymptomatic carotid stenosis with a good life expectancy, I would offer them a carotid endarterectomy. Okay. So what if a patient is symptomatic, but the duplex shows less than 50 percent stenosis? Well, it's less than 50%. So, that does not meet our indications for surgery. So no surgery is indicated. But all those best medical management things that you just mentioned, the aspirin, Plavix Hydrostatin is what I would do. Right.

So what if a patient has a stroke and the imaging shows a completely occluded carotid artery? So if it's already occluded, there really is no benefit to re canalization, so anticoagulation or dual antiplatelets in order to prevent progression, but with the understanding that there's a risk of hemorrhagic conversion of an ischemic stroke. Yeah. So you, we get these consults not too infrequently. Generally the damage has been done already. And so if you tried to open it up you could potentially risk. converting that ischemic penumbra into a hemorrhagic issue. So dual antiplatelet or anticoagulation. And then there are carotid stump syndromes, which we talk about later that are one of the few indications for operating on this. So what situation would an emergent carotid endoderectomy be indicated? So in the setting of crescendo TIAs I would want to do an emergent carotid endarterectomy. Yep. So these TIA symptoms are recurring and becoming more severe or lasting longer in duration is one of

the few emergent indications for a CEA. So, what is the most common non stroke cause of morbidity and mortality after a carotid enderectomy? Heart attack or MI. Right. So, it highlights the importance of a cardiac workup prior to a carotid enderectomy. We just said these things are rarely emergent and so getting a cardiac workup to make sure that they can tolerate the clamping of the carotid artery. And if they can't, you have other options such as transfemoral stents or TCAR nowadays. So when should you operate on a patient who recently had a stroke from a carotid stenosis? So it depends. So if there is a small stroke or, a TIA within two weeks once the symptoms resolve however large or hemorrhagic strokes, you would want to wait a bit longer, you know, maybe six to eight weeks. Yeah. And so there's more nuance to this, but in general you want to wait. a couple of days. So you don't create a hemorrhagic stroke from an ischemic stroke, but you also want to operate soon enough that they don't have recurrence of symptoms. So you make sure they're optimal. They're medically optimized, generally on dual antiplatelet, and you book them for surgery within the

week. If they've had a massive stroke or hemorrhagic stroke, you're going to wait a lot longer to let their brain recover before you do this. Okay. So now we're going to dive into Cerebral monitoring techniques as it regards to shunting during a carotid enderectomy. So shunting is the placement of a small plastic tube to maintain flow to the brain during clamping of the carotid artery. Some surgeons routinely shunt with the downside that it can limit the visibility of your distal end point. So let's say that we are on the Not routinely shunt side of things. What are the kind of general ways that you can monitor their cerebral perfusion during the case? Okay, well, I mean, one option is to do an awake carotid endarterectomy. So perform the surgery under, or local, and you have the patient squeeze a toy with the carotid clamped. And watch for their neuro status to see if they lose neuro function. In which case you would then want to shunt. You can monitor their stump pressures, so you measure the pressure of the internal carotid artery stump with a butterfly needle that's

hooked up to a pressure monitor. And if you want greater than 40 or 50 millimeters of mercury, if it's below that then you would need to shut. You could also do an EEG, , so you can clamp the carotid and watch for decrements in the EEG waveform. And if you see that, you'd want to shut. And you can also monitor cerebral oximetry. So the oximetry probe is placed on the forehead and you look for changes in that. Yeah. And so this might be more oral boards pertinent, but there have been some questions on this. You need to do some, if you're not shunting, you need to have one of these ways that you're going to monitor their neuro status. Or it's just sometimes easier to say that I always shunt that way. You don't have to worry about those. Are you a shunter or are you a selective? I'm a selective shunter, stump pressures or EEG, depending on the institution. Okay. So patient presents a few days after carotid enderectomy with severe headaches and hypertension with a normal neuro exam. What are you concerned about and what is the treatment? So yeah, this I would be concerned about cerebral

hyperperfusion syndrome. And the treatments, well, I'd want to get a CT scan and the treatments would be medical management by controlling their hypertension putting them in the ICU and seizure prophylaxis. Yeah, this is a rare condition. That can be lethal. And so it's very important to get their blood pressure controlled get a CT of their head, make sure their carotid's open. And normally it's a patient that's had bilateral high grade stenosis. And then, over three to six months you've opened up both sides. And now they their auto regulation of the blood flow to their brain is out of whack and they're hypertensive. So, it can cause cerebral edema and can lead to death. So, Definitely get them in the ICU, get the blood pressure control, get the seizure prophylaxis, probably get neurology slash neurosurgery involved. Okay. So what if a patient demonstrates symptoms of a stroke in the PACU after carotid enderectomy? What kind of, what are your first steps here? So I would of course want to emergently evaluate the patient and the high seal thing would be getting a duplex ultrasound and a PACU. Looking for that the patch went down or there's a

thrombosed internal carotid artery or some technical error that I'd want to go back to the OR. If that shows flow, then I'd be more concerned about a distant emboli or watershed infarct, in which case I'd want to get a CT scan. Yeah, exactly. It's like a fork in the road here. Is it something local at my patch? Did it, do I have some sort of issue there, technical issue or platelet aggregation? If you do, you go straight back to the operating room and do a thrombectomy. If your patch and every internal carotid looks patent, then you're worried about things in the brain. So you go to the CTA at that point in general, you're going to heparinize these patients too, unless you're concerned about hemorrhagic stroke. And so maybe wait until after the CT scan, but get the heparin on board as soon as possible. Okay. Which clinical scenarios would you consider carotid stenting over carotid endarterectomy? So I have patients who are just not good surgical candidates. So they have severe cardiac disease the history of neck dissection or neck irradiation recurrent carotid disease would be the patients I'd be thinking about that for. Yeah.

And I think every year the trans carotid artery revascularization is basically doing a. A stent with reversal of flow from the neck. I think this is becoming more high yield. So these patients have the same sort of indications that the stenting patients have. They, you know, have bad hearts. They have tough anatomy, a high lesion. They've had previous neck surgery. Something that would make doing a carotid artery not ideal. And so, it is a possibility on the test to keep in mind. And it has a low, the nice thing about the TCAR is it has a reversal of flow. So while you're crossing that lesion, it lowers the risk of stroke. Okay, so let's just talk about a couple of non atherosclerotic carotid lesions. So you have a patient that had a blunt trauma and is found to have an asymptomatic carotid dissection. What are you going to do in this patient? So the patient should be anti coagulated with either heparin or Plavix. And they need repeat imaging before they leave the hospital. Right. Yeah. You need some sort of blood thinner on board. Yeah, it's not

standardized and definitely make sure you're following them with a repeat CT or generally CT is better for these dissections because they go high, higher than the duplex can see. Okay, so patient is assessed with blunt trauma and found to have a symptomatic dissection. What are you going to do for this patient? Well, I'd also anticoagulate that patient, but they're symptomatic so that patient's likely going to require a stent. Right. Yeah. So dissections really aren't. Particularly amenable to open therapy. And so stents are really the best things for dissections. It's pretty rare for these patients ever need this procedure. Most of them do just fine with anti platelet or anti coagulation. But if there is the symptomatic patient and many times that they're symptomatic, you'd probably treat them for the, with the anti platelets or the anti coagulation and see if they recur while on that. But certainly if they have a symptomatic episode while on anti platelet or anti thrombotic therapy, then you definitely treat them for their dissection. Okay, a patient in status post blunt trauma with a traumatic occlusion of the carotid artery. What are you gonna do here? So if it's

occluded and they've already had a neurologic injury or stroke the damage is like before the other example has already been done. So they're unlikely to get better with intervention. So that patient, I would probably my only option would be anti thrombotic therapy. Yeah. Yeah. Once opening up these injuries, a lot of times leads to secondary injury. So, generally it's not recommended. So how should a patient presenting with a carotid body tumor be managed? A carotid body tumor requires resection but you want to consider embolization of the branches of the external carotid that feed the tumor prior to surgery. Yeah. So, if it's greater than five centimeters you can consider embolization to decrease your bleeding during the case, but yeah carotid body tumors need to be. Resected. If you have bilateral carotid body tumors, make sure you stage that and get a laryngoscopy to make sure you didn't injure the nerve between the two surgeries. But yeah, carotid body tumors need to be resected. Okay. So you have a young, otherwise healthy patient with a TIA and

is found to have beads of string appearance on their internal carotid artery on CTA. What is this disease and how is it managed? Yeah. So that's one of the buzzwords. Those beads of on a string appearance, that's fibromuscular dysplasia and it's most common in the renal and carotid arteries. It's involves fibroplasia, the medial layer of the blood vessel. And these patients are managed with anti platelet medications. How are recurrent symptoms on anti platelet therapy? The treatment would be balloon angioplasty. Yep, exactly. So, patient had carotid fibromuscular dysplasia and had a TIA. You'd put them on anti thrombotic or anti platelet therapy. If they recurred after that, then they would. You need a procedure and so, balloon angioplasty is the answer for these not stenting, not endarterectomy. These are kind of concentric fibrous rings that can be treated well with the balloon angioplasty. So, it could also be seen in a young patient with severe hypertension and they can

have it of the renal arteries is another common presentation there. And so in that case, you'd probably go quicker to the balloon angioplasty because they're not going to improve with antiplatelets. So let's go to a very classic question. We're back. We're looking at the thoracic outlet now. So Jason, take us through anterior to posterior of the thoracic outlet. Oh, yeah. I remember seeing this several times. So going anterior to posterior in the thoracic outlet, where you have to start with our subclavian vein, and then we have our phrenic nerve that lies on top of our anterior scalene, the subclavian artery behind the scalene. Then we hit our brachial plexus. Then our middle scaling and then our first rib. Yep, exactly. Just scrub in a first rib or section case or carotid subclavian bypass to get a good view of all of this anatomy. And shout out to Irene Yu, who we hired to do our images for us. She's a general surgeon at, time was in Buffalo. She has a great image in our book, so check that out. So what anatomic anomaly

puts patients at risk for thoracic outlet syndrome? Cervical rib. Okay. And where is the brachial plexus found in the thoracic outlet? So it's subclavian artery and it's along the middle scaling. Yeah. So it's kind of almost intermixed with the subclavian artery, but generally behind the subclavian artery. It's a beautiful, again, just looking at that image by Irene you and it's a beautiful picture of that. Yeah. Yeah. So which type of TOS is the most common and what are the classic symptoms? So the most common thoracic outlet syndrome is neurogenic 95 percent of them. So pain, weakness, numbness, tingling usually in an older distribution and those symptoms are worsened with elevation of the arm. Yep. And what's the treatment for neurogenic? Yeah. So, physical PT, physical therapies the first line, if that fails you diagnose with Scaling block or a nerve conduction test to confirm the diagnosis and then a first rib resection and

a scaling neck to me with neuralysis is the operation. Yep, exactly. So these patients a lot of times don't need an operation. They do well with physical therapy specific for TOS. If they fail it the scaling block really helps you know if they're going to benefit from this procedure or not, because this is not a small procedure to do on someone. So we want to make sure that they're going to benefit. And so then you do your first rib resection, your scalenectomy, the neurolysis is where you basically take the scar tissue off the nerve with your meds. It's very kind of satisfying. And you know, hopefully they do better. So a swimmer presents with a blue swollen arm. What is this and how do you treat it? so This is a subclavian vein thrombosis and we would treat this with catheter directed thrombolysis and eventual first rib resection. Yep, exactly. So compression at the costal clavicular junction and your thoracic outlet is what's causing this. So you have to get their vein patent first. So generally you're going to do a leave a lysis catheter in there overnight. Most people would send them home on anticoagulation

and fix it in a week or two. Some people do it during the same hospital stay. But they had just gotten lysis therapy, so that's kind of why it's maybe not ideal to do it in the same hospital stay. But then you do a first ribber section on them, just like you do for any other TOS, and they do well. Alright, so a young person with no atherosclerotic risk factors presents with ischemia to the hand. What are you concerned for here? So I'd be concerned for an arterial thoracic outlet syndrome. Although this is very rare so that patient would need a first rib resection and likely an interposition graft of the artery. Yeah. So the thoracic outlet is kind of rubbing on the artery so bad that the artery has become aneurysmal at that segment. And the aneurysm has thrombus in it as your body does with aneurysms and it can embolize to the hand. So pretty rare, but definitely seen and definitely seen on the boards too. So you don't want to just do your first ribber section here. You actually have to fix the aneurysm. So you need to do an interposition graft to fix

that. And so they'll need a first ribber section with interposition graft of the artery is how you treat that. Alright, so let's dive in a little bit to more thoracic outlet type anatomy, but so where is the anatomic stenosis that results in subclavian steel syndrome? So subclavian steel syndrome is from a occlusion. Yeah, so we're going to have an image in our book on this and you can take a look, but This is, you know, think of there's a blockage and very proximal subclavian artery. The vertebral artery obviously comes off distal in the subclavian artery, kind of mid proximal to mid subclavian artery. And so if you're working using your hand, doing hard work with your hand your hand is trying to get oxygen and blood flow. It causes the reversal of the flow down the vertebral, gives you that unsteadiness of gait and things, the vertebral basilar symptoms. So the way we treat this is we stent that proximal subclavian open. Or you can do a carotid subclavian bypass also

would treat the problem. All right. Very common in real life and in the boards dialysis access. So Jason, how long should a temporary catheter be left in place? Many places call these a vast cath, the ones placed in the ICU for kind of emergent dialysis needs. So no more than three weeks. Right. Why is that? They're a risk for infection. Yep. Okay. And then what is the difference between this and a tunneled or permacath? sO permacasts are cuffed, they're tunneled, so they're a lower risk for a central infection. They still have a risk of infection and a high risk of central venous stenosis compared with a fistula or a graft. Right, so it's much better than a, just the line coming out of the neck. These are tunneled, the skin protects it, but yeah the big concern here is central venous stenosis if they're left too long. So generally you want to get these out within three months or so. What is the preferred location for temporary dialysis access and what should be taken into account? So, generally the

right IJ, direct into the right atrium. But you want to think about where your permanent AV fissure is going to be and ideally avoid that side. Because you can get central venous stenosis which will could lead to failure of your permanent access down the road. Great. Great. All right. So we've gone past the catheters. Now we're going to place a fistula. Sort of what is the, what are the principles of deciding which arm to do a fistula? What type of vein to use? Like, what are the very basic principles here? Yes. Ideally you'd like to be in the patient's non dominant arm. And look at the upper extremities. Before looking at lower extremities, you want to start distal and not burn any bridges. So, this could mean, you know, radiocephalic fistula, if you have an adequate sized cephalic vein at the wrist, or a brachiocephalic fistula just above the antecubital fossa. Yeah, so there's a lot of nuance to this, and as I've practiced more, I've changed things, but on the board specifically, you want to, if they give you a 3mm vein, at the

wrist, you're probably going to do a radiocephalic fistula assuming the artery is good. So you start distally, you use the non dominant arm. And then that allows you more options to move up the arm. If that does not mature, reducing, getting permanent access improves their life expectancy. So getting good access really is a life saving procedure for these patients. And so there's a little bit of change now where if you have a, if they give you a patient with terminal cancer has six months of life expectancy, something like that, you can just leave the catheter in them. The central venous stenosis is not, going to be a problem for them over the longterm. But if you have someone that's gonna be on dialysis for 10, 20 years, you really got to get that permanent access into them as soon as possible. Okay. On preoperative vein mapping for an upper extremity AV fistula, what are the size criteria you need for the vein and the artery? Okay, for the vein you want you just mentioned it, but you want greater than 3mm throughout its course in the arm. Again, your primary veins you're looking at are the cephalic and bacillic. For the artery, it needs to be greater than two millimeters and

you want triphasic waveforms at the target artery in order to reduce the chances of Steele syndrome. So I've definitely seen this before where we'll, they'll give you a kind of a vein map and you have to decide where your axis is going to be. Yeah. And one thing I don't talk about here, you want to do the cephalic before the basilic if possible, because the cephalic, we don't have to transpose or superficialize at all. It's ready to go. And most people, so choose a cephalic, choose it as distal as you can, if they give you that option and that'll get them the quickest dialysis access possible. Alright, so let's talk about some problems with dialysis access. What if you have an AV fistula that's not maturing or it's malfunctioning, what is the major cause of this? Usually it's a venous outflow problem. Right, yeah. So veins are used to low pressures and they tend to scar down with high pressures and in the flow scene with AV fistulas. So it's almost expected that fistulas, grafts you're taking high flow of blood from the artery, diverting it to a vein. There is going to be problems over time and so, generally you're gonna have to do some

venoplasty at some point. Okay. So let's say, here we go. A patient is having high venous pressures at the dialysis center and they're, she's having to hold pressure for a lot longer than normal after dialysis. What do you think the likely problem is and how do you diagnose and treat it? Okay so that sounds like a venous outflow, a problem from a venous outflow stenosis. So I'd want to get a duplex ultrasound and my treatment would be a fistulogram and balloon angioplasty to relieve that stenosis. Exactly, yep, and so if the balloon angioplasty fails then you can stent it, but Most of the time, Blenangiaplastia work. Okay. So, we, we made this nice brachiocephalic fistula. They're following up kind of six weeks after the surgery. They want to know, Hey, can I use it for dialysis? So Jason, what are you going to look at on your ultrasound to see if it's ready to be used? So, I think you're referring to the rule sixes, right? Okay. So, so you want it to be six millimeters in diameter less than six millimeters deep. And greater than 600 milliliters a minute in flow.

Exactly. Yeah. So if it's too deep, you can't access it. And it would need to be superficialized. But all those are kind of the good numbers to know. A lot of times the flows will be much higher than that. 600 is sort of the bare minimum. Okay. So six weeks after brachycephalic creation, the fistula fails to mature. The same patient comes back and didn't meet that criteria. What are the likely causes and how can they be managed? Okay. Well, I'd need to get I'd start with a duplex to try and sort it out but it could be from inadequate inflow, from an asthmatic stricture. It could be a competing flow from side branches or it could have inadequate outflow. So that's what I need to know is my inflow, my outflow, and what the side branches are doing. So inflow problems can be treated with angioplasty or may need a revision if the issue is from the side branches. I need to either ligate or coil those side branches and if it's a outflow from the stenosis of the central veins I would require angioplasty or possibly stenting.

Yeah. And so if you've got big branches coming off your fistula, you know, five, 10 centimeters from the anastomosis, that that's going to divert the blood flow and it's going to depressurize your fistula and not allow it to get big and the other ones are kind of self explanatory. Obviously, if your anastomosis is tight. That's not going to be good or a venous outflow. Okay, so a patient is having breast pain in their hand and now they're getting some small ulcers at the tip of their fingers two months after a brachycephalic fistula creation. What is this syndrome called? How do you confirm it? And what are some of the surgical options? So this is Steele syndrome from arterial flow being diverted into the fistula and that results in ischemia to the hand. So if they only have occasional pain or coolness, you can observe these, but this patient you said has having some ulcers. So I'd want to perform weight flow flow analysis without compression of the fistula. And if there's a 50% improvement, when I compress the fistula, this would confirm my steel

syndrome. Perfect. Yeah. So you do a duplex and you put the probes on the fingertips and you determine, you know, how much is it improving when I compress this fistula? If there's a 50% improvement, then hey, they really do have steel syndrome. You don't have to treat all steel syndromes. Only if they have. Kind of breast pain or tissue loss. So they have a patient that just has a little pain at dialysis. They put a mitt on their hand and it gets manageable. The dialysis act, you just keep the dialysis access. So Jason, what are the sort of major surgical options? If say this patient does have true steel syndrome with tissue loss? Yeah. So I, the most definitive thing would probably be ligating the fish though, but you can ligate the fish to love band the fish to law. There's a drill procedure, so that's distal revascularization and interval ligation and proximalization of that inflow like I said, ligation is probably the most definitive but you could consider these other things as well. Yeah, and so this is kind of nuanced and The, the boards really seem to like drill procedures. So just make sure you look, you know, a quick picture of

that. You basically do a bypass around the fistula and ligate the brachial artery just distal to the fistula. And then proximalization of inflow is a really good one too, where you're basically changing the inflow from your brachial artery all the way up to your axillary artery. So it creates a longer circuit and more resistance. So less flow goes into the fistula. There's a lot of different ways to do this banding is an option, but it's not particularly popular. And it's hard to do well. And ligation is always an option. But so would you say you think it's fair to say like in an app site type situation, if they give you somebody that has threatened tissue or tissue loss or ulceration, to ligate that, but if it's more of kind of like a. A chronic problem, maybe doing one of these fancier, drill to try and salvage it is reasonable. Yeah I think with tissue loss honestly I don't think ligation of the fistula is almost ever going to be the choice. Because it's so hard to get good reliable dialysis access. So if you finally have reliable dialysis access. And you have tissue loss. I would choose the drill procedure. The

ligation is more for acute steel syndrome. So the day of the procedure, the day after the procedure, they come in with screaming hand pain, or if the patient had ischemic monomyelic neuropathy, which is the hand pain following the surgery, but you have good flow to the hand. So it's actually kind of a nervous ischemia issue. So those would be good reasons to do a. Ligation, but if you're out a few months and you, and the dialysis access is working, I would do something that preserves the fistula such as a drill or a proximalization of inflow would be my two go tos with the drill being my first just based on testing over the years. Awesome. Okay, Jason, let's move on to the lower extremities here. When are fasciotomies indicated and kind of what are the symptoms you'd expect that would lead you to do a fasciotomy? Well, I mean, certainly if the patient has extremity compartment syndrome, I do a fasciotomy. I started to worry about it with acute limb ischemia over four hours for that's when I would consider doing a prophylactic fasciotomy. Yeah, exactly. They're going to have patients that have lower extremity compartment syndrome

or acute limb ischemia for a prolonged period of time, you're going to want to do fasciotomies. They'll have tight compartments, a lot of pain with passive motion of the foot. And then classically patients will have pain out of proportion to the exam findings. So their leg won't look too terrible, but you move their foot slightly and they're jumping off the bed. That would be concerning. And if they've had a, anything that would have triggered compartment syndrome, you probably should do a fasciotomy on that person. So let's briefly talk. They like to talk anatomy about these things. So, Let's talk about where we make these incisions and how we access. So how do we make our incisions to access the anterior and lateral compartments? Okay. So, you would want to make your incision lateral to the tibia and in between the tibia and the fibula. So, generally an H type incision to both the anterior and lateral compartments, the incisions should be anterior and posterior to the intramuscular septum. So it can be really easy to miss the anterior compartment. So you need to be sure that you're close to the tibia with the anterior portion of your H

incision and the fascia to avoid missing it. Yeah, exactly. So this is your lateral incision. You're going to do that, you're going to open up, you have the intermuscular septum, you're going to open up above and below the intramuscular septum. But it's surprisingly easy, for whatever reason, that anterior compartment sort of creeps, kind of, medially, and so you have to really make sure you're getting that anterior compartment open. And so, okay what nerve can you injure with your lateral incision, and what deficit would you see with it? So your superficial peroneal nerve, which can lead to difficulties with the foot eversion. Yep. Okay. And to access the superficial posterior and the deep posterior compartments, where are you going to make your incision and kind of what are your tips on that? Yeah. So for this one, you make an incision two centimeters posterior medial on to the tibia. So the key to perform a complete four compartment fasciotomy is to make sure that the posterior deep compartment has been fully decompressed. So both the superficial and the deep posterior compartments are decompressed through the medial incision. Yeah, and so how do you feel good about having opened

up your deep posterior compartment? Yeah, so you need to take, you need to take that soleus off of the tibia. Exactly. Okay. So, do a little fasciotomy work. We're going to jump back up here and talk a little bit about some thoracic aortic injuries. So, in a blunt thoracic aortic artery injury, what is the most common site of injury? So, just distal to the subclavian artery in the descending thoracic aorta at the level of the ligamentum arteriosum. So that, that's where the aorta is tethered. So in blunt injury, that's where you're going to have your injury. Right, right. And so we're talking about the left subclavian artery. I should have added that there. And so that pseudoaneurysm is that, that's where it develops. And we treat this with the TVAR covered stent basically. So, there's other things we treat in the thoracic aorta. So what are the size criteria for treating a descending thoracic aortic aneurysm? So five, five and a half centimeters for endovascular repair. I guess if an endovascular repair is not possible, then the criteria goes up to six and a half centimeters. Yeah, because it can be quite morbid

doing, replacing the descending thoracic aorta open. So, we really would make sure that that thoracic aorta, they're going to benefit from that and letting it get a little higher. So what is one of the more feared complications of repairing the thoracic aorta? So, paraplegia is definitely a fear complication. Yeah. And so the spine has a lot of its blood flow coming directly off the aorta. And so when you cover this aorta, replace that aorta, you no longer have that blood flow to your spine. So what do you do to redi reduce the risk of this? Yeah. So this has been asked before. So you place lumbar drains Yep. And increase the blood pressure. Right. And so that's for your spinal profusion pressure, which is. The same thing is your central perfusion pressure. So you have two factors of that, your MAP minus your ICP. So your MAP is your blood pressure. So you drive up the blood pressure and then you lower the ICP and that'll get your spinal perfusion pressure as high as you can to help treat that. So you have a patient with presents, he's 50 years old, has hypertension, presents with new onset tearing chest pain. What is your concern and what should be ordered? So, I

mean, I don't want to forget about common things like acute cardiac or MI or cardiac event, but those are buzzwords that I would be concerned about an aortic dissection. So you know, once I would get my EKG and, do all the things for MI, but for workup of that aortic dissection, I'd want to get a CTA of the chest, abdomen, and pelvis. Yeah, many times there's only a CT done of the chest and then we have to kind of repeat it because these dissections when they happen, they propagate all the way down to the groins many times. So it's really important to get a C. Unfortunately, there's no other way to evaluate this. You got to get that CTA. So what is the anatomic landmark that differentiates a type A versus type B dissection? So that's your left subclavian artery. So proximal to the left subclavian to type A and distal to type B. Right, exactly. And so why is that so important from a timing perspective? So this is important because type A dissections are all surgical emergencies due to the risk of cardiac tamponade and rupture. So you need to

consult CT surgery immediately. And those require emergent surgery. Type B dissections can be emergent, especially if they have evidence of rupture or malprofusion. You know, those are surgical emergencies but otherwise they can initial therapy is medical. Right. Yeah. And so just to be clear, I don't want to make my cardiothoracic colleagues angry. It's acute type A dissection. Some people can have chronic evidence of chronic flaps and things like that. And the proximal aortic arch that is not an, a surgical emergency, but in general acute type A dissections are surgical emergencies and they need to have that fixed that night. sO when we talk about malperfusion and type B dissection, so this is what makes type B dissections emergent, right? It's either rupture or malperfusion. What kind of malperfusion can you get? Mesenteric malperfusion, primary bowel ischemia, but also potential even liver ischemia renal malperfusion or limb ischemia. Right, exactly. So you're going to see evidence of this on your CT scan. Either the kidneys aren't lighting up. The liver looks

dusky it's not filling with contrast well, or the legs but you also have clinical, you're going to place a Foley in these patients, you're going to check their labs, look for lactate, et cetera to check for mal, evidence of malperfusion sometimes you can't tell solely on a CT scan. So in a patient presenting with acute type B dissection, what are the principles of management? Yeah, so you want impulse control, so this is the blood pressure control with a short acting beta blocker that can be titrated. And you want to monitor for malprofusion, you know, doing serial exams, labs, and monitor the patient closely, especially things like urine output. Right. Yeah. You have to be able to decide to go back to the operating room if they have, if it's looking like there is true malprofusion. Okay. In a patient with an acute type B dissection and evidence of malprofusion, there are surgical principles in treating this disease. What are some of the surgical principles? So, you'll do, want to do typically an endovascular placement of a thoracic endograft. So a TUR in order to seal the,

Tear the entry tear and maintain blood flow in the true lumen and you want that false lumen to thrombo saw perfect Yeah, so that you know 75 percent of the time just placing that T bar will keep that flow going down your true lumen and fix Many of your problems be after this you still have to prevent perform angiograms to confirm that whether whatever you went to the operating room For that it is pain So you have to look at your renal arteries make sure they're paying you to look at your mesenteric vessels and your leg vessels but and so if there are further mesenteric issues then you have to kind of treat those as needed. All right, let's talk a little bit about mesenteric ischemia. So what are the four types of mesenteric ischemia? Okay. So there's for acute mesenteric ischemia, we have thrombosis and then no me or non inclusive mesenteric ischemia. Okay. Which is the most common type of mesenteric ischemia and how do you diagnose and treat it? Embolic is the most common type so patients we typically present with severe abdominal pain

and that's that classic pain out of proportion to exam and CTA is the best way to diagnose. Great. So what's the principles of managing this? So you want to heparinize the patient and take them to the OR for exploratory laparotomy, SMBA and valectomy. Okay. And then are you going to close this patient after you finish the procedure? No, for this one I would leave them open and plan to come back in 12 to 24 hours to re evaluate any marginally profuse bowel. So a planned second look. Yeah. And so that embolic patient's generally going to be a You know, a patient that's relatively healthy a lot of times that has a fib or something else, not a vascular path that has a kind of a spontaneous embolism to the SMA. But there's a different type of patient that has sort of a different presentation of a similar disease process. And so this is your heavy smoker who has a severely diseased aorta. So what type of mesenteric ischemia do you suspect in this patient when they come in with the abdominal pain?

Yeah, so there's a usually thrombotic disease, right? And so this is instead of an embolus going down partially down the SMA. This is actually at the origin normally of the ostium of the SMA. Sometimes these patients will present sometimes in a more of a sub acute fashion because they've had chronic ischemia for so long. So yeah, that's just kind of a two different patient populations to look for there. And that's in the key that they'll tell you in the STEM. So these patients will likely require mesenteric bypass versus stenting of the ostium rather than an embolectomy is important kind of differentiation there. Okay. Which disease process embolic versus thrombotic will have proximal jejunal sparing? Yeah, that's the embolic because it lodges distal to that first branch off the SMA you know, three to 10 centimeters or so distal to the ostium. Whereas, your thrombotic patients will not have any sparing of the small intestine because like you said it's at that takeoff or at that ostium. Yeah. And so how do you identify the SMA to perform an embolectomy on it? Yeah. So you'll lift up your transverse colon up towards the head cephalid and follow the the base

of the transverse mesa colon. And just to the right of the, of your ligament of treats you'll be the SMA. And so you need to mobilize your LOT in order to gain access to that SMA at its origin. Great. Okay. So let's move on to a different one. What are the characteristics of mesenteric venous thrombosis? So it was typically subacute so multiple days of abdominal pain and they may have bloody diarrhea. I bet you have caused this as a bariatric surgeon. That's what I've seen. I have had a couple of consults of patients that had recent abdominal surgery and then kind of presented with belly pain and were found to have this. So kind of what are your principles of managing this? So, you know, generally as patients well at times, or they can't have an underlying hypercoagulable disorder or like you say, you know, recent abdominal surgery. So we'll get a CTA and sometimes we'll see bowel wall thickening, mesenteric edema. and potentially thrombosis of SMB or, SME or even the portal system. So, we'll want to heparadise these patients. They

rarely need surgery, but if they, certainly if they developed a ischemic bowel then that's when he'll operate. And in, in rare cases you may even have to give TPA although not ideal in a post operative setting, or a lysis cath, catheter into the superior mesenteric artery. Yeah, I know, it sounds weird. Sounds weird and this is sort of, you know, in a rare situation where they're really sick. And the heparinization isn't helping. And so you drip it into the SMA because obviously you can't really put a lysis catheter in the SMV unless you did it tips or something like that. So, it has shown to improve this in patients with severe mesenteric venous thrombosis. But the vast majority of these patients will do okay with heparinization. So I would just answer heparinization and serial abdominal exams on the test. You know, understanding kind of what puts these people at risk for this. And the basics of treatment of this and you only resect the bowel or you only open the abdomen if they're getting sicker and then resect the bowel at that point. But yeah all right. So last one what are the characteristics of NOMI? Okay. So this is your non inclusive mesenteric ischemia.

So these patients are generally critically ill on multiple pressers and they may have impaired cardiac output or cardiac failure. And what you typically see is you'll see ischemia in your watershed areas. So that Griffiths and Sudex point, the splenic flexure, the upper rectum, and the treatment is to reverse the underlying low cardiac output. So resuscitation, improvement of cardiac functions, and similar to the venous thrombosis OR is reserved for only if you have to resect a ischemic bowel. Yeah, generally the patient they're going to give you on this is the patient in the cardiac ICU with an Impella device in. They're about to do ECMO, et cetera, and they're lactates going up. And so they want you to check out that. And so generally you just got to tell them, Hey, we got to get better flow before when we're not operating. So, okay. So we're going to break vascular up into two sections. So we've completed the first one, I think 48 minutes is more than enough of anyone can handle. So we're gonna do our quick hits here. So Jason, what are the most common sites for an upper extremity embolus to lodge?

The brachial artery at the bifurcation of the radial and ulnar artery. Great. And what is the most common site for a lower extremity embolism to lodge? Again, a bifurcation. So this would be the common femoral artery at the bifurcation of the profunda and your SFA. In a patient with a ruptured AAA with hypotension that is getting a crash laparotomy, where would you get proximal control? So you want superceliac aorta, and you'd go through the gastropathic ligaments underneath the cruciate diaphragm, and you just, initially just press the aorta against the spine. Great. A patient that has a ruptured AAA and is being transferred to you, what do you tell the outside? Center to keep their blood pressure. Yeah, so this is a permissive hypotension. So it's a stop blood pressure between 80 and 100. Great What is the most common organism in graft infections? Yeah, staph epidermidis, sort of staph epi. It's a slow Insidious bug. Great. And what is the treatment for popatilum entrapment syndrome? Resect the medial head of the gastroc Okay. Or we're saying, or if it's not the gastric causing problems, sometimes there's a crossing band or the popliteus muscle

is compressing the artery. You can figure this out with your MRI a lot of times. Okay, what if a patient has refractory hypertension and is found to have beads on a string appearance in the renal arteries or has the same angiographic finding on the internal carotid? What is this? Yep, so that's fibromuscular dysplasia, and I say most common in renal arteries, and balloon angioplasty is the treatment method of choice. Yeah, and so you're not going to get, they're not going to call it beads on a string, they're going to show an angiogram and you're going to have to know that's what it looks like, so make sure you know what that looks like. Alright, great, that was the best and most fun I've had yet. Can't wait to talk vascular part two with you.