Good afternoon everybody. So as rich said, I'm going to spend the next 10 minutes talking about surgical therapies for diseases of the thoracic aorta. I'm gonna start with a brief history of aortic surgery and then focus most of my talk on some of the more traditional open surgical techniques for aneurysms and dissections of the proximal thoracic aorta, namely the root ascending an arch. And this is gonna dovetail nicely with hostiles talk as well with his acute pathologies. And then I'm gonna spend some time on some of the more modern, less invasive hybrid and endovascular techniques that are being employed to attempt to avoid the potential morbidity is associated with strong economy, cardiopulmonary bypass and circulatory arrest. So there are many different aortic pathologies and aneurysms which can involve any part of the aorta and can predispose to the acute pathologies that spoke of including dissection, intramural hematoma and penetrating aortic ulceration. The first written documents containing descriptions of the heart aorta and aneurysms come from ancient Egyptian papyrus dating back to 1500 BC. The term aneurism actually comes from the Greek aneurism a which means to widen or dilate. There's been ominous mention of aneurysms continued throughout the centuries. But it wasn't until the mid 18 hundreds that surgeons began to think about methods to prevent aneurysm. Rupture. The first surgical treatment of aneurysms involved. Simple ligation is seen in this post mortem specimen on the right. In the late 1800s. Newer methods arose for the treatment of aneurysms, including insertion of wire coils into an aneurysm sac to obliterate it some surgeons would. Even pass a current across these wires to induce clot formation and obliteration of the aneurysm. At the turn of the century, Rudolph made, this is an american surgeon from new Orleans made a breakthrough in direct repair of aneurysms by recognizing the importance of not just obliterating an aneurysm but also maintaining or restoring the vessel continuity. This complicated diagram on the right shows his technique of preserving the inner lumen by placating the aneurysm sac over an inner stylistic tube, which he then removed. Surgeons then began experimenting with home a graft, aortic replacement and vascular anastomosis. And ultimately led to the standard techniques for exclusion and graft replacement of the aorta Synthetic fabric grass were first developed in the 1950s and 60s, uh but also required the development of cardiopulmonary bypass and the techniques of circulatory arrest to allow for the repair of the most complicated aneurysms of the aortic arch. So this is the reason we operate on aortic aneurysms and aneurysm as it increases in size. The complication rate dramatically increases in this bar, graph you can see for aneurysms that measure 4 to 4.544 to 4.9 centimeters. There's an approximately 5% annual risk of rupture dissection or death As the size increases to greater than six cm. The annual risk of dissection rupture. Death is greater than 15%. And so that's why the literature has sort of settled on 5.5 cm as the surgical threshold. And this is when the complication rate begins to exceed the surgical risk. So acute aortic dissections, it's a true surgical emergency. 20% of aortic dissection is die before reaching the hospital. Without treatment. There's an approximately 2-3% risk of mortality per hour for the 1st 24 hours. The Stanford classification is probably the most widely used because of its clinical significance. Type a dissection meaning proximal to the left subclavian or acute cardiac surgical emergencies requiring medium anatomy, cardiopulmonary bypass and oftentimes hypothermic circulatory arrest. Whereas type B dissections 80% of the time can be treated non operatively with antihypertensive management and oftentimes elective subsequent TVr repair. The goals of surgery for a Type A dissection. Our reception of the tear initiation site, re establishing true loom and blood flow, false loom and obliteration replacing the diseased aorta. So this is uh an interrupt picture from a dissection that I did a couple of years ago. Just to orient. Uh The top of the screen is the patient's head at the bottom here you can see the epa cardio fat of of the heart which is being displaced inferior early and in the middle is this large aneurysm of the ascending and arch of the aorta with the path of demonic purplish discoloration. You'll see when it's dissected and then on the right is after I've arrested and clamped and opened up the aorta. You can see the three layers of the uh of the aorta with the into MMA, the advent Ishan And in the center this fresh rhombus of the dissection and this shows the repair that we performed for this patient. Uh We resected the entire A sending and route as well as up to zone one of the arch. Um You can also see my calculation strategy here. Uh Sorry. So typically when you do an elective aneurysm case, you can relate the right atrium here for venous drainage to the cardiopulmonary bypass circuit. And then oftentimes you can calculate the a sending or arch of the aorta. However, with the dissection, the first thought process has to go into your cancelation strategy. And so luckily in this patient the nominate artery was not involved. And so I was able to so an eight millimeter graft onto the a nominate artery uh to allow for perfusion. And this also allowed for selective and grade cerebral profusion. Um After arresting and performing a dissection of the ascending and arch and beginning a period of circulatory arrest, I was able to snare the base of the nominate artery and then continue perfusion up the carrots to allow for brain perfusion during the repair. So in 1900s for William Osler, he's the father of internal medicine, said there's no disease more conducive to clinical humility than aneurysms of the Aorta. So I'm gonna shift gears here from the acute pathologies and talk more about elective aneurysm repair for aneurysms involving the aortic root and ascending aorta and aortic root replacement can be performed with the reception of the dilated sinuses of val salva and re implantation of the coronary buttons into the graft that you could see on the right. Here's a very large root aneurysm. You can see that begins at the valve but then quickly tapers to more normal caliber by the distal ascending aorta which allows for clamping of the aorta here. Uh so that you don't have to circle rest the patient. Aortic root replacement can be performed with or without aortic valve replacement and just depends on if there's any pathology, either stenosis or insufficiency of the valve. Um If an aortic valve is necessary, there are commercially available valve conduits that have either a mechanical valve or a bio prosthetic valve already incorporated into the base of the graft. And for those patients who have a normally functioning functioning aortic valve, a valve sparing root replacement can be performed and this is the val salva graph that is most commonly used that does not have a valve incorporated into the base of the graft. It has a vertically pleated skirt here at the base, which sort of recapitulates the sinuses and also allows for easier re implantation of the coronary buttons. This is a cartoon and then an operative diagram on the operative picture on the right. Uh basically looking down the barrel of that val salva graft in a valve sparing root replacement in the center. You can see the three uh sorry, You can see the three leaflets here in the closed position. You can see that all of the aneurysm all sinus tissue has already been resected and is being replaced by the graft. The coronary buttons have yet to be reimplanted in this diagram. And then this suture line here basically anchors the annual list of the of the aortic valve to the graft itself and provides for homeostasis. So even more complicated or aneurysms involving the arch which require re implantation of the branch head vessels. This necessitates a period of circulatory arrest during which blood flow to the brain is interrupted. Unless of course you employ some degree of selective anti grade cerebral profusion that I've already mentioned. So this is a case of a 72 year old woman who had an a sending tube graph for a type a dissection many years ago. And then she had a large growing residual arch aneurysm and type B dissection. And this is basically the operation that she got. So she had a reduced anatomy. We sewed a graft onto the right to the right axillary artery here. Uh and that allowed for initiation of cardiopulmonary bypass and also for selective and grade cerebral perfusion which again is performed by clamping the base of the nominate artery which allows you to continue to refuse oxygenated blood up the carrots. She also had a frozen elephant trunk placed, which is does not appear in this diagram, but is directly inserted into the proximal descending aorta and then provides for a landing zone for the arch graft, which is then sewn to it, followed by re implantation of the three head vessels. And this is the technique of the frozen elephant trunk ivy's can be performed to confirm true lumen placement and then a basically an anti grade tiv are what we call a frozen elephant trunk is deployed directly down into the descending aorta to cover any ministrations that also provides distantly for an anchor spot for subsequent ivar if needed. And then also approximately provides for a landing zone for the distal end of the arch graft before re implanting the three head vessels. This is just an inter operative picture of a very large greater than seven centimeter aneurism that was involving the a sending an arch and you basically can see the heart's getting displaced inferior early. You don't even see it in the middle of the median strain on the heart would typically be sitting here, but it's completely being displaced by this very large aneurysm and on the right is the repair that we perform basically a root repair ascending an arch with re implantation of all three of the head vessels here. So I've provided a general overview of the standard open surgical techniques to treat thoracic aortic aneurysms employing medium anatomy, cardiopulmonary bypass and circulatory arrest. But what's even more exciting in this field is coming up with more creative, minimally invasive and hybrid techniques to tackle these very difficult arch arch aneurysms and to try and avoid stir anatomy bypass and circle rest, which can be very morbid. This is a case of a 58 year old woman who had aneurysm dilatation of her arch and proximal descending Aorta. She had multiple comorbidities, significantly increasing the risk of bypass and circulatory arrest and her anatomy was actually unfavorable for a complete endovascular approach. The patient's aneurysm extended pretty much all the way to the nominate artery takeoff. So any endovascular approaches bar we need to cover all three of the arch branch vessels. The patient actually did get a stern ah to me, but we avoided cardiopulmonary bypass and circulatory arrest by undergoing central arch de branching. Um As you see in the cartoon on the right, basically was able to avoid cardiopulmonary bypass by simply placing a side biting clamp on the ascending aorta, sewing a 12 millimeter. Try for catered graft to the aorta clamping that and then subsequently re implanting or sewing each of the three head vessels so as to never completely interrupt blood flow to the brain during the procedure. This then allowed for subsequent basically, Zone zero Tiv are retrograde, which covered all three of the head vessels. So, and finally, I just wanted to touch on the future of aortic aneurysm surgery, which involves minimizing the morbidity of these traditionally very invasive surgeries by avoiding stir anatomy altogether. The nexus aortic arch stent graft system is just one example of many newer branch graphs which are being developed and accomplish this goal of avoiding stern. Ah To me, this particular graph requires a staged procedure which first requires cervical de branching so that all cerebral profusion comes off the nominate artery, but it then allows the patient to avoid strain artemis altogether uh by endovascular deployment of this modular arch graft, which has an a nominate artery branch to it. And so finally, I'm just gonna end with a short video clip which shows a simplified overview of the deployment of this graft. So axillary and femoral access are obtained. A guide wire has passed its past retrograde up into the nominate artery, followed by the deployment system. Radio opaque markers are then used to position the a nominate branch. The system then deploys its a self expanding system deploys from the nominate artery down to the descending aorta. And you can see during the deployment we still have profusion up the head vessels here. The next step is actually to release the graft from the deployment system and that's performed by turning this knob, the deployment system is released, the catheter is removed, leaving this main module in place. However, there's a second component here. So guide wires then past retrograde down into the ascending aorta and the a sending module of this graft is then passed via this deployment system. Again, radio opaque markers are used for positioning, Make sure that we stay above the coronaries of course, so we don't include them. And then this a sending component is deployed. It docks into the main module here and basically creates a seal. A plug can be placed in the left subclavian artery here to prevent back pressure and now you can see all blood flow to the brain is through this, a nominate artery branch. So this is just one example of the many new branch graphs that are being developed and provide an elegant solution to some very challenging arch problems. Even in otherwise healthy individuals. Total arches can potentially be a pretty morbid procedure. Uh, and so, you know, by pushing the envelope of these endovascular options, we're really at the cutting edge of aortic arch surgery and what keeps the field very exciting. And so I think we'll stop there and we'll hold comments or questions for the end. Thank you very much.
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