Dr. Barnhart provides educational material for young surgeons and surgical trainees so that they may adopt successful techniques related to the surgical technique for On-X(R) Ascending Aortic Prosthesis Implantation.
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my name is Dr Glenn Barnhart. And I've been asked by Cryolife to uh talk about the onyx valve and specifically to provide educational material for young surgeons just starting out and surgical trainees uh so that they may adopt techniques that are successful with the use of the onyx valve. My background is having done training at the Medical College in Richmond Virginia as well as at the National Institutes of Health in boston Children's Hospital. I practiced at the Medical College of Virginia at as well as Sentara Heart Hospital in Norfolk Virginia for nearly 20 years and then was asked to be executive director of the Swedish Heart and Vascular Institute and Swedish Medical Center as well as chief of cardiac surgery there in Seattle where I was for approximately 11 years and recently have retired. Let's talk a little bit about the ascending aortic prosthesis. This is a very nice prosthesis. The composite graft that uh crowded life has created and developed. It is an onyx valve. It has a standard uh tip extender which I think is very important because as one inserts this down into the aortic position. Uh This effectively works as a snowplow, pushing everything out of the way and I think is the best holder really. That's uh that's on the market for any of the mechanical valves. Nice sewing ring. The real advantage to this valve and a composite valve is the valve salvo effect which you see here in this cup and then finally the graph. Um one of the things about this that's that is a little bit different that surgeons just need to familiarize themselves with is the is the holder. And so this has a handle here that you can see in a plunger. And when I press this one is going to see that the the holders here, the the extender valve holder are going to uh oppose each other and get closer. And so that one pulls that out. So this is one without the valve. And you can see that this is an extension here and then these see how this collapses. When it's when you're not pressing this, this doesn't collapse. When you press it, it does collapse and allow for the surgeon to easily pull it out. It's important to understand that once this plunger is compressed and it is, is removed, it should not be reinserted. That is very important. That's unlike the isolated aortic valve replacement and which of course the delivery system is different and one is seeing, you can't see what's going on down here. So once that's out it's out and should not be reinserted. But it's a very nice prosthesis, very nice valve, nice sewing ring and um in terms of the tray that it comes on in terms of size urz and all of the sizing considerations, it's exactly the same as an isolated aortic valve replacement. Um and so the tray will be the same, but the release mechanism is entirely different. Let me speak for a minute about rotation of the valve. When we, when we're using the ascending aortic prosthesis, of course, the ascending order prosthesis comes like this delivered to the surgeon. Um When we have this uh delivery device inside, the way the mechanism works is that there is a plunger here and you can see and this is true for the isolated aortic valve. Also, one should make sure that one can easily turn the valve before insertion before any sutures are placed in the valve. Then once the valve is in place, um one can remove it easily by simply doing that and taking it out once the valve is in and of course this will no longer be this long because you will have cut it to length if you still don't like the position of the valve. Once you can look inside, then one can insert the standard standard isolated aortic valve rotator, which is here and you can push it back down through here. And once you can visualize it you can see this so that then you can once again turn the valve to the desired location. So the ascending aortic prosthesis comes with this dark line down the center, it's it's on there primarily for orientation. Um some surgeons are concerned about its location and once you have this in your hand, you feel that it's actually thicker. An easy way to to not have that become an issue at all. Is it simply placing it and orienting in the non coronary sinus, so if the left is here, the right is here and this is placed in the non coronary sinus then it becomes a non issue. The substantial reduction in risk of patient prosthesis mismatch. We all know that PPM is a very serious issue. Pebereau identified this back in 2010 and has published papers on it subsequently to show that mortality rates are substantially increased if the patient's prosthesis is not matched to the patient's body surface area. So the Eo ai becomes a very important factor and one should always keep this in mind when picking a valve for a patient. This can be anticipated. Patients are markedly obese pre operatively. Uh if they are small stature small frame typically women are can be uh challenging size. And so in those patients, once you're seeing them in the office you can look at the transfer echocardiogram, ask your cardiology colleagues to measure the diameter. If you're still unsatisfied that that's not an accurate measurement then you can get A. T. E. Pre operatively which can be a bit more accurate and even move to a C. T. Scan. So all those things are are things that you have in your toolbox to try to identify patients that are going to be a problem in the operating room. You want to have a mindset for that going into the into the operation. As seen on the graph the effective orifice area index Is quite an important factor and a huge advantage of the onyx valve. So uh patients can be implanted with a 21 valve down to uh body surface area or up to a body surface area of 2.1 and a 19 valve up to a body surface area of 1.7, which is a pretty good size individual. So the valve has incredibly good flow dynamics and this is one of the huge advantages of the valve to to make sure that that the patient doesn't suffer from PPM, which carries a very significant mortality risk. Uh These uh flow dynamics are true not only for the isolated aortic valve but also for the ascending aortic prosthesis. So that's important to keep in mind. So in this video we're going to do an onyx mechanical ascending aortic prosthesis. And uh in this pig heart we've already transected the aorta. This is about the level one would be considering transacting the aorta uh in the in preparation for doing the prosthesis. I'm actually gonna cut this down a little lower because here is the right car near button and here is the left corner button. So we're gonna take a little bit more of the aorta because we don't need quite that much and I think I can show you now better the take off of the um the right is right here and the takeoff of the left main is right here. So the first thing you're gonna want to do in a ascending aortic prosthesis is you're going to cut out the leaf, it's just like you would be doing in an aortic valve replacement. And now we're gonna wanna uh excise the buttons because we don't want to get the prosthesis down in there and be excising the button. So this is the left button market hold right there and I like to leave about 3-4 mm of Rim from the Austrian, you see here how I'm not cutting completely free, just cutting the wall of the aorta, The pigs costume is quite large. So we've got plenty to work with here. I'm gonna use this hand held carter here and I think the key about buttons is to make sure that you're not trying to free it up too much. Remember, you can always free it up more later on if it looks like it's under any tension and you if you get it too loose then it can lead to Qingqing and after each we sort of stopped and check to see how much length we have developed and not so much length, but just freedom of the actual button. That looks pretty good. Yeah, and I think it's really important that one creates a very smooth um cut around the button, you don't want any divots because those will believe invariably, so in other words, I'm gonna make one here because obviously we're not concerned about that, but if you ended up having something like this, even with suturing, that could be a real problem. That little v divot there, that's district and when we get the prosthesis in, we may actually do a little bit more of that. But for now we're gonna stop there. Now we're gonna go to the right button which is here. Let me take that. You hold that over there, That's great. And remember, you can always cut off more. So we're gonna be trans mural here. But then when we get down here, we'll end up with the same advantage holding it in the back. We're gonna do that with the electrical and again, use our electric artery to free up the right button. And again, we're gonna stop right there because we may need to free more, but we'll see, you can always free more at a later time. We're gonna round this up like we talked about before and again, we're gonna try to keep this as round as possible. So now we're gonna size And I've got a 25, this is obviously a big heart and a very large um heart. And so this is a 25 and you can see where this is just too small. There's a space here and there's a space over here. And so next we're going to use a size 27 29 size or you can see here and this is the largest prosthesis made. So uh this will work, this will work fine. Um that's the um conical end and then we're gonna take the replica end. Just give us a feel for what it's gonna look like once it sits in there and you can see that that actually looks quite good. And I should note that these sutures are basically placed just like in an aortic valve replacement. No different. The only subtlety is that care is taken to make sure in when you're really doing this in the real world is that the sutures are pretty close together and I in this case, I would use pledge. It's to ensure that you've got the best deal possible. The pig heart has quite a lengthy mussel shelf and so that's what this slit is back here. I just wanted to point that out. We did that just to free that area up a bit, we're gonna resect it, but we left it in place. One thing you may want to attend to when you're doing the first few of these to see how this button can get sawed a bit on the future. Uh if they're placed tightly, so just be careful with that to make sure that it doesn't cut into the, into the button. Sometimes what I'll do is take a five up rolling and actually it's a lot of times it will be in the way, I'll just pull that back, but I don't think that'll be necessary today. So you can see that we have all the pledges in place right button left button there well out of the way and now we're gonna once again size you always after you put the sutures in whether pledges or not pledged we size again before we thought it was a 27 29 which is this size er here and it looks about right, you can see how there's some drag on it. So that's what we want, just a little bit snug right in that area there. So in this area I think we'll that uh this area will conform to that area, if you see that type of thing. You know, you'll see occasional patients with very large aortic annually of course today we're doing a lot of aortic valve repairs, but in patients who can't be repaired and you're doing this prosthesis, you'll see this. This is never a problem. There's always the analyst will always conform to the sewing ring of the prosthesis. Alright, So we're choosing the 27 29. Let me just demonstrate the replica one more time. You can see how that actually fits in there quite nicely and should be perfect. This is what the prosthesis looks like when it comes to the table and again you want to make sure that this, that you can turn this handle um like this, what I'm doing is turning this back and forth to make sure that I'm holding it down here on the cuff to make sure that that will turn because if I get it in there and I want to rotate it, we'll make sure that it can easily be rotated. So we're gonna provide a little tension on each one of these sets of sutures and we're gonna lower this into place. And obviously unlike an aortic valve, you can't really see in there quite yet the way this is released and I should note, let me pull this out. And again, pointing out the extended holder here acts as a as a snowplow effect and basically pushes everything out of its way so that we get nice seating. But what I can do from looking at the top here is I can make sure that it is in place along the analyst everywhere. That's what I'm looking at now to make sure that it's well seated all the way around, making sure the buttons are free and haven't been impelled by the by the graph. So now to get this out, we simply push this plunger and it pulls right out. Now at this point, I like to take the graft like to take the graft and cut it off to some degree. We're obviously not going to be doing the distal anastomosis. So you want to leave yourself ample graft that, you know, you're not leaving yourself short here, but you need to have this much of this craft out of your way to be able to look inside and we take the plastic probe and we push that down on the inside and we check real quickly and I'm looking all around and I see no pledges anywhere. You can see down into the barrel there that there really are no pledges, we adjust the light maybe just a little bit as you can see. It's nice, smooth, glistening, left ventricular myocardial, down in there, no evidence of any pledges anywhere. It's very important to do that. So I'm gonna leave that probe inside and then we are going to tie these in in this case the prosthesis does not seem to be riding up anywhere, but I'm still going to use a technique to somewhat triangulate these sutures and I could look down inside with the probe in and I can see that there are no pledges out anywhere and that it is well seated, we're gonna put this one down over here and again. I'm checking to make sure this is down all the way, which it is in terms of not time for mechanical valves in general. This isn't just an expert mechanical valves in general, one needs to make sure that a portion of the analyst is not riding up. And so I do see a little bit of this riding up, I know that it fits, I've already confirmed, so I'm not worried about it not fitting, but it will sort of tend to watermelon seed out a bit and so I'm going to go to where I saw that pledge, It's starting to sneak out a little bit and tie that down good and anywhere I see a pledge it hanging out now. I tend to go to that site and In this case it's 180° often where I was, which is what you want to do, you might ask. So what if the pledges are out of the loom and well obviously number one, I worry about the seating of the valve. But even more importantly, I'm concerned about the homogenic potential for that over time because the pleasure in the left ventricle outflow track provides turbulence and turbulence as we know produces through eugenic activity. And so the whole point of this is to, to have a nice smooth laminar flow. That's one of the big advantages of the onyx valve because of the way it's structured and with the flare aspect, it really helps to to have extremely laminar flow. If you look at a onyx valve in a test tank, the flow is amazingly laminar These leaflets of course come up at 90° and um provide essentially no obstruction to outflow from the left ventricular chamber and so we want to do everything we can to optimize that situation. I've always liked the onyx sewing ring both in the S. O. A. V. R. And also in this craft because the sewing ring really conforms nicely to the annuals and that's especially important in a diseased aortic angles where the and this of course is sclerotic and calcified. So now we're gonna look down this area here and see if I want to show you that all you see really is down into the ventricle and nice glistening myocardial in the outflow track there, so no pledges anywhere. And again, if we needed to rotate the valve, um we have the rotator. So here is, we could simply put the rotator in and turn it so you can see here how I'm able to rotate the valve and turn it with impunity if we wanted to do that. Why would we want to do that? Well, number one for flow um across the coronaries and number two, if there were any any tissue or anything dangling out, especially in the disease, uh fanatic or in a in a sclerotic annual issue, may occasionally have a lump of tissue down there and you'd want to have that the leaflets in a situation where they would not be uh impaled in their movement. So let's go. Now look at our coronary buttons and how we're gonna do that. So this is the left coronary button. This is the right coronary button here and this left corner button still seems a little tight to me. So I'm gonna um take our quandary. I'm gonna divide that tissue to allow it to come forward. You want to err on being away from the coronary a little bit. So I'm looking inside there, see what direction it's going. Yes, slowly do this. And then with each one of those maneuvers, I sort of stop and check. You can always tell what's impeding that coronary to advance. You can sort of stop and look now that is beginning to look a little bit better. Obviously the heart when it fills up and plus the val salva, you've got to take in account a couple of things. One is when the heart fills up, this is going to expand and this is going to come up. This is pulled down a little bit by the prop we have here to hold this up, but this looks pretty good. So now we're going to um do that anastomosis, we're gonna do the left button first, so we're gonna do this over here. Now what I want to comment on is that when you create the cipher, but remember it can always be larger. And what I want to do is also take a marking pen and I want to put where I think the absolute center of this is going to be. And that gives me some feel for exactly where to make the opening in the graft, it's just a landmark to use. So now we're going to open it up down below. And again, the same thing applies here. Remember sort of a measure twice cut once concept, you can always make the opening bigger. And so I'm gonna make this probably smaller than it needs to be. And I'll show you how to deal with that there in just a minute. You want to make sure that the sutures are very close together post clearly or as confident as possible because you never want to see this area again, take my time back here. The little key maneuver I think is to have your assistant just gently retract that out of the way. Now this is a case where you need to or at this point you need to assess your length here. And I think I'm just about right and you could make this a little bit bigger if you wanted to. That's the point I was making before. But I think, I think what I'll do here is just take up the pig button, keep these a little closer together. Now I left this divot here on purpose, you can see where that is a real potential bleeding site. Right, Let me take that off now scott. And so that's, that should always be rounded right there. I'm gonna go below it in this case. But that could be a real problem. So I think you can appreciate here how we've got just the right amount of tension on that button. You don't want it to be too floppy because it could kink but you don't want it to be under tension because that will obviously cause bleeding and possibly stenosis at a later time. So I want to see if I can show you here, you see here how this is completely pain and you need to always check this when you get finished. You'll be surprised sometimes that it's not quite as big as you want it to be. But here it's just wide open. Looks great. Okay, the right button is going to be a similar process. Will take advantage of big situation here and turn this around and once again, I think we're just about right with our um with her attention. So we're gonna, yeah, we're gonna market, give us a good feel for and just, you know, you want to take a couple of moments of here just to make sure you know, but it over here, put it over here, see what's happening to the to the Austrian back here, make sure it's not under too much tension, it's not being torqued, all those things need to be attended to and we're gonna put this right in the middle. There we go. Now. The other thing, another thing I want to point out is that you want to air on trying not to get this too low because if you get it too low, you run into conflict with your needle with the valve housing, which is down here. So I'm also aware of that. I'm gonna make this a little bit higher than what that mark show because you don't want to have that problem. That's a not a good issue. Alright. And then let's see, let's just check again. I don't think we need quite that much tissue. So if you've left yourself, a lot of tissue can always go back and trim that off, get it just right and again, trying to keep that as round as possible. Obviously this would be about 180° because you can't switch the human heart around like this. But I thought for purposes of demonstration would be better to show this here. You see. I think that the valve housing is right here. Obviously I wouldn't do this in the real world because it shouldn't be metal on the titanium, but it's just very close. So if this is cut way down here, that can be a very bad problem. Trying to get the needle around that. So, I always just be aware of that. I want to make sure that my sutures are full thickness on the button because they will bleed if they are not. You want to catch the advantage issue, just like you're doing an aortic aortic anastomosis, seeing a transplant. Something that nature, it's very important to get full thickness on the button. Again, I'm assessing here, I think I'm gonna be okay again, I'm not gonna open that up anymore. You needed to you just take the handheld carter and go up here a little bit bigger. You don't want to get the whole the whole in the graph too big because then you're stretching on the coronary button that will cause tension tension will cause bleeding. I think it's really important to use bio glue on the buttons. So we're gonna demonstrate that search scissors. Um We're once again we're gonna look down the barrel here and make sure that coronary is easily probable as it is like that. Now let me get the heart back in the normal anatomical position for the camera, that would be like this. And the bio glue. There really is a technique in which to make that work well and what you want to do before using bio glue in the procedure, the syringe must be purged of the residual air space and the applicator tip must be primed. Each applicator tip must be primed prior to bio glue application. Priming ensures the bio glue solutions are properly mixed. The surgeon should compress the plunger and expel a narrow ribbon of bio glue approximately 3cm long onto a sterile disposable surface, for example, a sponge gauze or towel caution bio glue polymer rises very quickly. The surgeon must apply bio glue immediately after priming, pausing between priming and application can cause polymer ization of bio glue within the applicator tip should this occur, replace the obstructed tip with a new tip and repeat the steps for applicator tip priming do not continue to apply pressure to the plunger. Once the tip has occluded that way it's not running everywhere and you just keep gentle pressure. If you stop, obviously it'll stop up and that's okay but if you squirt it out like this it just goes everywhere. So same thing over here and then you let it sit up. Now obviously we're not going to do a um graph to aortic anastomosis. This was cut off for the purposes of this video shorter than it would be. Let me just make a couple comments on how to size the aortic graft anastomosis when one is doing the anastomosis um Yeah this is it pig's aorta. The tendency for surgeons is to leave this too long. And if you leave this too long, what happens is on the back side once this anastomosis is created. Um you end up with a buckling back here. And I've actually seen that caused homogeneous city. And the patients was having multiple T. I. S. And strokes from that area because you end up with the tissue actually uh buckling like this. So the way to avoid that is to make sure that when you pull this up to cut it that you allow for a little bit of forward movement in the aorta. Um And you're gonna have a little bit of tension again the tendency is to go I don't want to be too tense because that will cause bleeding. And you certainly don't want too much tension there. But you want to have just a little bit of tension, those are for the new user. I think that's really important to remember remember that if it looks like there's too much attention after you finish the anastomosis. The other thing you can do is actually free up the aortic arch. You can actually go up into the aorta, free up the head vessels of great vessels and so that and mobilize the aorta so it'll come down a little bit. Um The final thing one can do if that anastomosis does bleed is actually take a felt strip and put it around it and tighten it here on the front uh and run a four up rolling back and forth. If any of you have experience with transplants then you would know that that's a very common technique used in transplants when there's a significant donor to recipient. Um Aortic discrepancy in terms of size. The question that comes up occasionally is, can one cauterize the button site on the scene. And in my experience over the last few years I've been faced with this once or twice where the button just has to be in that area. So let's say if you are set up and it happens to be an extraordinarily high um left main or right. I have actually cauterized over this area. So the uh and and it was there were no untoward effects. It's not advised to do that and one searches for other ways to do it. But if you have to do it, you have to do it. I think precautionary measures should be taken if one does that in that what I did was place a reinforcing suture on this side and a reinforced suture on that side. Also bio glue is quite helpful. And the third thing to say is that the way the val salva graft is soon to the jail. We've graph that uh it's uh reinforcing suture lines so that it will it will not um tend to migrate away from that site. So all those things being said, I think it's uh not does not your first choice but sometimes it's your only choice just because of where the button is. And if you take those precautionary measures, I think it should be fine. In my opinion. The question of length is always an important one in terms of how long uh to to make the graft or where to cut the graph. So if the aortic prosthesis is here and the a standing order is here, one needs to put a little bit of stretch on this to cut the graph. I think in most surgeons minds and certainly was mine in my mind early on, the tendency is to be concerned about the graft being too short. Once you cut it. Obviously that's a very serious problem because you've done all the work below the buttons and the and the actual graft implant. Um So you need to keep that in mind and make sure that you don't have it too long. The problem with the graph being too long is that if you have a standing order here uh that you're gonna anastomosis too. And the and the graft here out here, the graft will, once it's fixed it'll actually buckle and it can buckle like I'm demonstrating here. So that that buckling effect results in a ridge inside the graft. And that ridge can actually be thrombin genic. I've actually seen a couple of cases of that one in particular where the patient continued to have thrombosis bolic phenomenon thrown from that site even on Coumadin. Uh and that patient had to undergo repeat operation to have the entire graph removed. So suffice it to say that that can be avoided with proper length of the graft and proper length of the graph can be achieved by making sure that there is enough stretch put on the graph to try to replicate what's going to happen once the aorta is pressurized. The other thing to keep in mind is that once the graft is sewn in and it looks to be if you're concerned about how tight it is, one can mobilize the distal aorta just circumferential e and go into the head vessels a little bit. So the aorta can then come down and accommodate. Finally for many of you who have done heart transplants, one can place a teflon felt strip around the graph and allow that thomas to be compressed by that with a bolstering, polling suture on top. So with all those tricks in mind. Of course bio goo being placed on that anastomosis initially One can safely do that anastomosis with proper length. One of the discussions around the choice of a send aortic prosthesis is the valve for graph graph size uh and the annex a sending aortic prosthesis. The composite graft that I have in my hand only has a maximum inner diameter of 26. Um I have used this graft for a number of years. I've never seen that to be a problem. I think all of us, especially those of us who have done heart transplants in which there has been a significant amount of aortic to aortic size discrepancy have learned to tailor our anastomosis. And if one is cognizant of a much larger aorta uh than the graft, then one can accommodate for that very easily from the beginning. Um and that can be that can be handled very nicely in the event that one completes the anastomosis. Uh Interior lee and you still feel like that you have too much aorta. One can always split into a split V. V. In the graft here to take up any remaining aorta that needs to be um to complete the anastomosis. So there are plenty of ways to handle that and I don't think clinically that's a significant issue at least it has not been in my opinion in my hands, there are a couple of questions that have come up in the past about the ascending aortic prosthesis number one, in terms of positioning of the valve, the valve should be positioned identically to the isolated aortic valve replacement. And that is to say that the leaflet should be left in the left, right, commis. Sure. And the noncommercial uh in terms of orientation And that can be done of course with the rotator. The second issue is anti coagulation, anti coagulation for this valve. Currently it is 2.023.0. So when one is using bio glue in procedures such as aortic or mitral procedures, there are several instances in which I would routinely use it. In my opinion, that would be on the coronary buttons. Um Certainly on the aortic graft anastomosis. If one is doing an aortic dissection, then I would use it on the aortic anastomosis in those cases. And certainly any tissue anywhere that looks uh fragile or friable, a place that bio glue is essential is when one is doing aortic root enlargement and on the outside of the heart, never use bio glue on the inside of the heart. But on the outside of the heart, where the tongue of tissue goes down, uh that has on augmented the aortic root, one needs to place bio glue in that area because bleeding in that site is difficult, if not impossible to control after an aortic root enlargement with bio glue that will not be a problem. And so bio glue is essential to be used in that area to remove bleeding risk after an aortic root enlargement.