Portal de Periódicos da CAPES

Discussion: Session 3—Dissection

2002; Elsevier BV; Volume: 74; Issue: 5 Linguagem: Inglês

10.1016/s0003-4975(02)04263-7

1552-6259

D. Craig Miller, Steven Lansman, Duke E. Cameron, Yuji Hanafusa, Teruhisa Kazui, Joseph E. Bavaria, Stephen Westaby, Satoshi Ohtsubo,

Cardiac Valve Diseases and Treatments

DR D. CRAIG MILLER (Stanford, CA): The topic is basically aortic dissection, but we did touch on valve-sparing root replacement. So, before we dive into dissection, let us bring up some questions about what Dr Cameron mentioned about valve-sparing root replacement, particularly in children with Marfan’s. In the infantile form of Marfan’s, it is a terrible problem. And Dr Cameron told you, the homografts are not going to last very long; we do not have a good solution. You are not terribly happy, if I understood you correctly, with the Yacoub remodeling approach to valve-sparing in the kids with Marfan’s. Is it going to be better than or worse than a homograft? DR DUKE E. CAMERON (Baltimore, MD): We do not know if it is going to be better than a homograft. We are hoping that it is. I know that the homografts are dismal in young children; they degenerate very, very quickly, and some of them will only last 3 or 4 years in the small or very young child. So the valve-sparing approaches do not have to be much better to be superior to the homograft. The infantile Marfan’s are almost a completely different group. These are the ones that are more likely to be female than male; they have predominantly mitral, not aortic, disease. It is almost a different kettle of fish. And it is very unusual that a child needs an operation for an aneurysm in the first 10 years of life. It is our impression that aneurysm rupture or dissection in the first 10 years of life, even in some fairly large aneurysms, is extremely rare. So we have a high threshold for intervention in the first 10 years of life. What we are really talking about most of the time are the adolescents who have aneurysms about 5 or sometimes even 6 cm. We think the adolescents behave much more like adults and should be operated on according to those criteria. DR MILLER: If you are facing a 2-year-old or a 4-year-old with the rare ascending aneurysm, what are you doing today? DR CAMERON: We are doing a Yacoub type repair with some kind of stabilization of the lower end of the graft, But the numbers are very small. I really cannot tell you how well that operation works for that age child. DR MILLER: You mentioned that you are hoping the reoperation rate would be 10% to 15% at 10 to 15 years. Are those roughly the numbers? DR CAMERON: That is what I quote to the parents of children, or of the young adults: that I estimate that the reoperation risk is going to be 5% to 10% at 10 years. DR MILLER: For Marfan’s children and young adults, not the older Marfan’s? DR CAMERON:That is right. DR MILLER: Would that be acceptable, in your book, in the older Marfan’s? DR CAMERON: I do not know if that is acceptable. I know that it is acceptable to a lot of my patients. When I present them the alternative of a lifetime of anticoagulation versus a 10% chance of needing a reoperation and getting a mechanical valve, a lot of them (half of them) are opting to take their chance with a valve-sparing root replacement. DR MILLER:Before we leave valve-sparing root replacement, no one mentioned it in the context of acute type A aortic dissection, where we think we have enough on our plate anyway. It is a big operation; it is the middle of the night. It turns out the groups in Hannover, Lubek, and Homburg, Germany have taken the bull by the horns; and if you think about it, the David reimplantation is probably the most hemostatic root replacement operation we have. The only thing that can bleed is the distal suture line and the coronaries, and I think Dr Haverich and his colleagues have five, 10 cases: there is a paper in press. Is Dr Kallenbach here? Would he care to bring us up to date on the Hannover experience with David reimplantation valve-sparing root replacement for acute type A dissection? It sounds like a very intrepid move, but maybe they are just ahead of the rest of us. DR KLAUS KALLENBACH (Hannover, Germany): So far we have performed about 30 such cases of reimplantation in type A acute aortic dissection, and we will publish the first 22 cases soon in the European Journal of Cardiothoracic Surgery. And the outcome is very convincing. I believe this is a very good method that can be performed very well by a surgeon who is experienced in this technique even under the circumstances of an emergency operation. DR MILLER:And when the root is destroyed, or in the Marfan’s, when are you doing the whole root using the David reimplantation? DR KALLENBACH: We look at the valve as we usually do in nonemergency cases. And if we feel we can reconstruct, we do it. We glue the bases, if necessary, and if there is not too much dissection into the root and into the coronaries, we try to reconstruct and do the reimplantation. DR MILLER: Maybe I did not express that clearly enough. How often do you save the sinuses nowadays? These are rarely daylight elective cases, acute type A dissection. Are you saving the sinuses at all or are you always doing a David valve-sparing total root replacement? DR KALLENBACH: Sometimes we still do it. We believe that the goal of removing all diseased tissue is a very good concept, but sometimes, in a few patients in whom we feel there is no need for doing reimplantation, we do a supracoronary repair. DR MILLER: Any comment from the panelists on taking it one step further proximally? We have all been focused on getting more radical distally, but doing a reimplantation probably makes a lot more sense than putting in a composite valve graft proximally, which we know is not ideal. DR JOSEPH E. BAVARIA (Philadelphia, PA): I think it might make more sense than a composite valve graft in certain patients, but I do not think it makes any more sense than a standard resuspension for patients who present with relatively normal aortic valves and relatively normal sinus segments before their dissection. DR MILLER: Why do you say that? The Cleveland Clinic group has told us clearly in a paper in 2000 that if you add a CVG you are increasing early hazard; you are going to have fewer people surviving to worry about down the road. How can you justify doing a CVG of any sort in a cavalier way? I think you have to be more specific, and that is what I am asking you. When? DR BAVARIA: When do you use a composite graft? DR MILLER: Yes, whether it be the Freestyle you like and talked about, or the David valve-sparing root, or a mechanical valve? DR BAVARIA:I think that if you are going to need to do a root procedure (a biological root procedure such as a David procedure or a Freestyle), it may be preferable to a mechanical composite graft in this patient population. MR STEPHEN WESTABY (Oxford, England): I think you have got to get back to treating the pathology in front of you. In non-Marfan patients, the extent of the dissection in the sinuses is enormously variable, but as was mentioned before, it really seldom excavates the left coronary sinus. It may not excavate the noncoronary or the right coronary sinus. I think in only about 30% of our cases was there no significant aortic regurgitation. So there is absolutely no point doing a more extensive root resection and repair if the pathology does not warrant it. Going back to the Marfan patient, the question you have got to ask yourself is, are these repair procedures durable in patients with dissection? And we do not know yet. I think if we have good results with aortic root replacement, either biological or mechanical, then I think a lot of us feel safer about sticking to knowing what we can do well. And, as I have said, the emphasis is to have a live patient at the end of the operation. DR MILLER: I doubt many of the Hannover cases were Marfan acute dissections. Are these questions addressing just that point? DR HANS-JOACHIM SCHAFERS (Homberg-Saar, Germany): Yes, exactly. What actually made me use valve-preserving root replacement in that context was the observation that the patients that come back for redo operation always have some dilatation of their root. Often it is a Marfan’s patient in whom the root should not have been preserved in the first place; these were reoperations that we did in Hannover in the old days. We never published that. This is what made me propose, and actually practice, more aggressive surgery whenever the root is dilated at the time of operation in acute dissection. Dilatation really is a soft term now. So if the sinotubular junction is perhaps 35 mm, my feeling is that a straightforward supracommissural replacement may not be the best answer. DR MILLER: While you are up there, Dr Schafers, you are the biggest champion in the world of the Yacoub remodeling approach. Most everyone else has given it up, especially for Marfan’s patients, except you and Sir Magdi. Do you do that in the acutely dissected acute type A root? DR SCHAFERS:Yes DR MILLER: Do you like that? You must. DR SCHAFERS: It bleeds a little more than the reimplantation operation. But then with reimplantation in the face of acute dissection (and I actually did the first patient in Hannover a number of years ago), I am always a little scared that I am doing something to the patient that I may regret later on. So if I do not absolutely have to do it; I prefer remodeling, where you can stay away from some areas of the root. DR MILLER:But you will admit it can be a lot less hemostatic with that mile of suture line up and down and that lousy tissue. That scares me a lot. DR SCHAFERS: Absolutely. What I do is give some cardioplegia into the root once I have done my root replacement, and then spend 5 minutes pulling on the sutures and tightening them again, and that usually results in a very hemostatic root. DR LARS G. SVENSSON (Cleveland, OH): I think the reimplantation operation in the acute dissections should be considered more often. If it is a straightforward-looking valve without dilatation, I think a resuspension is very good. And one of the things that I think is useful in those patients is to carry a bit of the graft down into the noncoronary cusp and sew that to the annulus, because that is often where the problem results down the road. But the reimplantation I think is a very useful technique in the patients who have got dilatation. But you need to be very careful that your sutures are right on the annulus so you get good hemostasis at that internal suture line. As you just said, it is a very hemostatic operation. And then for the buttons, I always use a doughnut or a lifesaver sort of ring to buttress them, and that works pretty well. DR SATOSHI OHTSUBO (Saga-city, Japan): Our institutional indication for root replacement includes a destroyed annulus and pathology of the aortic root, including Marfan’s syndrome. But except for such indications, we favor aggressive resection of the noncoronary sinus and try to remove more of the dissected part of the aortic wall from the aortic root. But our method is not identical to the operation described by Dr Schafers. We leave a 10-mm aortic remnant of the aortic annulus so that we can place Teflon felt and reinforce the proximal aortic stump, and this is a very safe technique. We have had no proximal reoperations among 88 patients for problems with the remaining proximal part. DR MILLER: Before we leave valve-sparing root replacement, several people mentioned that the noncoronary sinus is usually the most destroyed, and that is, in my personal book, probably the only indication for a Yacoub. But I do it as a uni-Yacoub; simply take a tongue of the graft and replace the noncoronary sinus. Then it can be circumferential up above. Let us move on to dissection then. Let me start off by saying that we have talked about axillary cannulation in terms of SCP (as an easy, poor man’s way to do SCP), and I think Dr Griepp got everyone to believe that. We have not heard anything about axillary cannulation today for acute type A dissection, except that Dr Bavaria said it was 5% or 10%. I would hope in your most recent year it is 100%. Let us go down the panel and find out how often you use axillary cannulation for CPB in acute type A dissection. DR OHTSUBO: I use it in a patient who has a preoperative pulse deficit. I have utilized axillary cannulation in about 15 patients, or about 10%. DR CAMERON: We have not used it in acute type A dissections, but we would probably use it if we went on bypass with femoral cannulation and were concerned about malperfusion. MR WESTABY: I am not sure you can cut down on the axillary artery that far. I have just started to use it. Most of the series I showed you was using the femoral artery, but I think the axillary artery has got advantages, so I am just getting to grips with it. DR YUJI HANAFUSA (Osaka, Japan): Currently, in acute type A dissection, right axillary cannulation is always used. DR MILLER: One hundred percent? DR HANAFUSA: Yes. DR STEPHEN L. LANSMAN (New York, NY): I would say 85%, most of them. I think it saves a few minutes of circulatory arrest having to recannulate the graft at the end of the procedure. DR TERUHISA KAZUI (Hamamatsu, Japan): I would say it is about 10% in the recent series. DR BAVARIA: Ten or 15% axillary cannulation for acute type A dissections. DR MILLER: Still a minority. Keep coming back; we will keep trying to convince you. DR MILLER: Let us see a show of hands from the audience. For acute type A dissection, how many of you are routinely or most of the time using the axillary artery when you initially go on the pump? That is 25%. Those who still use the groin or the arch? It is a majority. All of you should keep coming back. DR MILLER: I might add that there is another fascinating paper in press from Hannover; this describes an old technique, but I have been afraid to do it. Axel Haverich and his group are directly cannulating the true lumen in the distal arch under echo guidance. If it works, it is great; if it does not work, you are in big trouble. DR GEORGE J. MAGOVERN, JR (Pittsburgh, PA): Following up what Dr Westaby and Dr Bavaria mentioned, we have had safe results in patients, for example, more than 70, with an acute type A aortic dissection in which we can see the tear in the ascending aorta, but in whom we simply replace the ascending aorta with the cross-clamp applied and do not do the hemiarch. We tan the distal suture line with BioGlue and reinforce it with felt, cannulating the subclavian artery. I guess I wanted to get your comments on whether you think that is a safe operation in your hands or whether you would recommend continuing with the hemiarch. DR MILLER: You are recommending then, Dr Magovern, still to clamp on all acute dissections? DR MAGOVERN:The pathology would be that the tear is in the ascending aorta near the coronaries and that you can see that the tear has not included the concave part of the aortic arch. You can see the tear going around the lateral aspect of the ascending aorta, but it has not included the medial aspect of the arch. DR MILLER: So the arch is dissected, as it almost always is, and the tear is in the ascending aorta. Do you clamp still, or do you always cool down and at least do an open distal anastomosis? DR BAVARIA: I think it is not wise to clamp. This is an intense operation that can happen any time of the night, and I think it is the kind of operation where you should have a standardized approach for your hospital. That is when you get the best results. We looked at this question. Using clamping is how we did all or most of the cases, from 1988 to 1994, during a 6-year period, and our results were not that good. So we just decided from then on to do a standard open arch in every case. DR LANSMAN: Somehow this question comes up at every symposium. I remember sitting next to Dr Borst at Aortic Symposium II, and answering the exact same question. We have always practiced the open distal anastomosis, and that way we get to examine the aorta in every single case in our series. The tear was located in the ascending aorta in only two-thirds of the patients. I think it was 62%. In 23%, it was in the arch. I think in 6% the tear was in the descending aorta, and 8% had multiple tears. So that even if you saw a tear in the ascending aorta, there might also be a tear in the arch. Since we have practiced this technique, we have the occasion to take a look at where the cross-clamp was, and I am sure many people here have seen this as well. When you take the clamp off, you have created another almost circumferential tear from the cross-clamp. So you have done a very nice repair, fixed it with glue, or whatever, and you take the cross-clamp off and you have an almost circumferential tear 2 cm downstream. So I do not think it is a good thing to do. I think the distal anastomoses should all be done open. MR WESTABY: I invariably cool, because I think if you cross-clamp, as Dr Lansman just said, you propagate damage. Those dissected tissues disintegrate, and I find it extremely difficult to believe that you can predict the extent of the tear even on transesophageal echo. I do not think you can tell where the distal end of your tear is. So every single case I think should be done open. DR MILLER: Both Japanese centers would cool and look, I assume DR CAMERON: We would cool and look; do all of them open. I go one step further and say we would not even cross-clamp the aorta at all unless there is so much AI you can not handle it. DR MILLER: So, Dr Magovern, I am afraid you found no solace up here from this group, nor from myself. DR MAGOVERN: Let me rephrase it then one more time. Has there been any change in thinking with the availability of BioGlue? DR MILLER: We are going to get to BioGlue in a minute because that is not all good news. There are some very serious issues about BioGlue. I must add before we leave the distal anastomosis controversy, that we looked at our data. Dr Bavaria knows this very well; we looked, since we have a few in our group who still clamp. And, lo and behold, there is no measurable difference in outcome so far. Has that affected our practice? No. But we can tell you for certain that cooling and looking does no harm. DR ENIO BUFFOLO (Sao Paulo, Brazil): I have a comment. I think that one important thing is to look at the aortic arch by introducing a regular fiberscope. It is impressive, the images you get. You are able to look as far as the celiac trunk with a fiberscope, and this does not take more than 2 or 3 minutes. We usually do this with the open distal technique. DR MILLER: Looking for big reentry tears? DR BUFFOLO: Yes, because this may be a significant indication for introducing an auto-expandable stent under direct vision. DR MILLER: That is the ultraradical Kazui approach. You look, and if you see something bad downstream, you add a stent graft under the open arch. DR OHTSUBO: May I make a comment about cross-clamping? As I showed in the video, I make a decision by cross-clamping manually, using fingers, and monitor the right and left radial artery. And also we monitor the size of the true lumen and the size of the false lumen in the descending aorta by TEE. After we cross-clamp using fingers, if the size of the true lumen decreased and the size of the false lumen increased, we do not touch the ascending aorta and just wait for circulatory arrest. DR MILLER: You never clamp the ascending aorta, as Dr Cameron suggested, which I think is smart if you can avoid it. Sometimes there is wide-open AR. DR JOHN FEHRENBACHER (Indianapolis, IN): A practical question. You have an acute type A dissection, hemodynamically stable, no end-organ ischemia. I hear and I know from the BioGlue study (where we had a 16-multicenter trial) that the good data are not always published. In that group of 300 cases, there was a 30% mortality for acute type A dissection; 180 surgeons did these operations. When you look at about a 1% to 3% per hour death in an acute type A dissection (again, these are stable patients), is it better to delay an operation 3 or 6 hours and let a more experienced surgeon do it? Or should it be done in the middle of the night? DR MILLER: That is a good question that we wrestle with even at our place. If you get away with it, it is wonderful. If something bad happens before sunup, you do not have a leg to stand on medico-legally. You and I and all of us have seen too many dossiers where the lawyers just go after it. You can not defend that. If it works, great. DR BAVARIA:I would like to answer that legal question since I come from Philadelphia, which is the highest legal place in the world. I think that you can take these patients and send them to a referral center. I think that you can stand on that legally. What you can not stand on is any delay in your process. You can use the data from the IRAD study, which is published, with about a 25% overall perioperative mortality rate for every surgeon in the whole country. You can also use the data from the BioGlue study, which showed a mortality rate of 30% for 180 surgeons. DR MILLER: But the question was, once they get to you, are you going to sit on them until sunup? DR BAVARIA: No way DR MILLER: And in your center? That is the question, right? DR FEHRENBACHER: That is the question DR BAVARIA: But there are questions also from the referring doctors whether to send these acute type A dissections, or do them in their own hospitals. Is that what you are trying to ask too? DR FEHRENBACHER:I think that enters into this question. We have hospitals with cardiac surgeons in our city that would send these cases to our hospital, and it obviously delays the operation 2 to 3 hours to do that. But again, if it is only a few cases of acute type A dissection a surgeon does, mortality could be 50% for one surgeon and 5% for another. MR WESTABY:I think this is a great question because it is just so contentious. You see that the average mortality for type A dissection is about 25% or 30%. But some surgeons have operative mortalities of 75% or 80%. Particularly in a system like Britain’s, where surgeons are coming through having never done a dissection and perhaps never having seen one during their training, it is very intimidating to start in the middle of the night with your first case. We all know that a lot of these cases do remain stable for a long time, and you can pick them. If there is no blood in the pericardium and no tamponade and the patient is beta blocked and you keep the pressure down, they survive and they are transferred for many miles in Britain to specialist centers. I think in many respects you are right: if you do not have a legal system that is influencing your clinical practice as much as it is here, then it may be very sensible to get a different surgeon to do the operation later. I think it is a very contentious question. DR LANSMAN:Some of that data on the early mortality I think is old, and I am not sure how accurate. I do not know if the rate of death really is that high per hour that early. I just saw a recent paper from Italy with a large number of patients who refused surgery for type A dissection, and the mortality was only 50%: it was not 85% in 2 weeks. We have waited some hours to stabilize the patient, often until morning, if, as Dr Westaby says, it looks reasonable. I know at Symposium II, Dr Bachet told us that was immoral, but we have done it. DR MILLER: We did not answer your question completely, Dr Fehrenbacher but thank you for bringing it up. It is a good one. DR RAJ K. BOSE (Tucson, AZ): I would like the opinion of the panel about something that I have done for the last three type A aortic dissections. In all type A dissections, I cool and release the clamp and take a look down in the arch. In the last three cases, there has been a tear in the inner aspect of the arch along the lesser curve. And instead of doing a hemiarch, during the last of which I had some troublesome bleeding at the distal end, what I did was I squirted glue, plastered the layers together, and put in horizontal mattress interrupted sutures with pledgets outside and more BioGlue outside to reinforce that. And amazingly, for the first case, there was not a drop of blood coming out, so I continued doing it for the next two, and I have not had any trouble with it. I would like to hear if anyone has had that experience? DR MILLER: So what are you suggesting? Instead of a hemiarch, you are doing a Teflon-reinforced distal and then a hemiarch? DR BOSE: No, doing just an interposition graft for the ascending aorta. DR MILLER:And just gluing the arch? DR BOSE: Right, and for the inner aspect of the arch, just repairing it with horizontal interrupted sutures, keeping the pledgets outside. DR MILLER: And you have had very good luck in three cases. My only advice would be, do not do it for three more. You are asking for trouble. Quite honestly, it is a good question, but I think we have grown beyond that with our current techniques and circulatory arrest. We just have to go look for the tear and chase it. MR WESTABY: I too think there are dangers to doing what was described. On one unfortunate occasion, I operated on a type B dissection, having been told categorically that it was a type A, and this is not that unusual. Since I was there, and the arch was open and I could see the tear, I decided I would repair the type B tear with glue, which I felt was entirely reasonable at the time. I put the glue down the distal arch and firmed it up and it looked okay. But when the patient woke up, he was paraplegic. I could not work out the mechanism of the paraplegia, and I still do not think I can, but it certainly put me off a great deal from squirting glue down into a hole in the distance. DR MILLER: That brings up BioGlue, which we will get to. DR MANUEL IRARRAZAVAL (Santiago, Chile): Most of the speakers have stated that they have a different decision-making in Marfan’s, so my question is, what do you mean by Marfan’s? In Steve Westaby’s slide, it was very obvious diagnosing the two sons, but what if that same patient had a daughter of normal size; would she also be a Marfan’s in your mind? Because some of the Marfan’s do not have the physical appearance of a Marfan’s, but histologically, genetically, and chemically they are Marfan’s. Do you have any decision-making tools to aid in the diagnosis of Marfan’s, and do you change the decision-making on that basis, not relying only on the morphologic appearance of a patient? MR WESTABY: I entirely agree that in dissection and in elective aneurysm surgery it is not uncommon to find people that are quite clearly not Marfan’s patients but have typical Marfan’s annuloaortic ectasia at a very young age. We all recognize that that is a group that you see quite commonly. When you do a dissection on a patient like that, even though he is not officially a Marfan’s, if you find aortoannular ectasia and a dilated root, you must treat it like Marfan’s syndrome and replace the root. DR IRARRAZAVAL: You think all annuloaortic ectasias are Marfan’s, in other words? MR WESTABY: No, no, they are not. That is the whole point. DR MILLER: But the associated connective tissue disorders are very variable and they are very common. So if the aorta thinks it has something like Marfan’s, treat it like Marfan’s, even if the patient is 5 feet tall. I think most of us would go along with that. MR WESTABY: Precisely. DR BAVARIA: Exactly. DR MILLER: Any other comments from the panelists about when you get in there and it looks like Marfan’s, but the patient otherwise clearly is not? Be aggressive. DR CID S. QUINTANA (San Juan, Puerto Rico): I would like to know from the panel, how often would they request a cardiac catheterization looking for coronary disease, especially in elderly people with acute type A dissection, if at all? DR MILLER: How often do you ask for a coronary angiogram? Let us just give a simple percent without editorial comments. DR BAVARIA: Zero. DR KAZUI:We do not routinely perform CAG in the case of acute dissection. DR LANSMAN:I am going to say 1%. MR WESTABY: I do not go for cardiac catheterization at all, and I would add not even in patients who have had previous coronary surgery. DR MILLER: You can figure it out when you are there? MR WESTABY: You can, but you have got one objective in mind, and that is to get the patient through the dissection repair quickly and expediently. DR CAMERON: Certainly less than 5%. DR OHTSUBO: None of the patients. DR MILLER: That is pretty conclusive. How about in the audience? Let us look at the real world. How many of you in general, or 80% of the time, do not ask for a coronary angiogram in a patient with an acute type A aortic dissection? A vast majority. I think that is progress thanks to these meetings and a lot of hard work. Can we talk about two other topics? One is philosophical and ethical about when we say “no.” The other is BioGlue, and Jean Bachet is still here, I believe. We have opened it up to GRF glue, too, because our Japanese colleagues use that. You have heard a lot about glues. You just heard from Dr Fehrenbacher that in a prospective study, even with glue, you have a 30% mortality rate in this country for acute type A dissections. So it is not solving the problems. Are we abusing glue now that we in the United States have access to it, and what are the downsides of glue? This question comes up every 2 years also (has for 16 years), but I think the world trend is getting away from glue, certainly in Europe, and perhaps in Asia, because in the case of GRF glue, the complications are coming out many years later, with full-thickness necrosis and false aneurysms and this and that. Hans Borst told us 10 years ago, and Jean Bachet, that they just used too much formalin or it was too warm or whatever. And in the expert’s hands it probably is safe, but I think the trend is away from glues. But now we have BioGlue and everyone thinks it is as safe as candy. Is it? The reason I bring it up is that just in the last year I have seen two cases of aortic root necrosis 6 and 9 months a