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Ann Thorac Surg 1995;59:1403-1404
© 1995 The Society of Thoracic Surgeons
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Introduction |
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 Top Introduction |
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DR CHRISTOPHER J. KNOTT-CRAIG (Oklahoma City, OK):Were the patients who had a root replacement in whom aortic regurgitation developed late patients in whom you did not use Teflon felt around the base of the aortic root, or were they patients in whom you were using that technique?
DR JONES:We always have used felt. Originally, the felt technique described by Mr Ross with interrupted sutures was employed. Since that time, I have switched to a technique incorporating the felt with interrupted sutures of the proximal row. I do not think the problems with regurgitation are at the felt suture line. Hopefully, the felt will prevent annuloectasia over years. Regurgitation is most likely a problem relating to the cryopreservation technique. Recently, Dr Barratt-Boyes has published a very nice study showing the loss of extensibility and elasticity in cryopreserved leaflets.
DR KNOTT-CRAIG:It should be reasonably easy to document that, because you have echocardiographic data of both early and late evaluation. Did you see any discrepancy in size either at the aortic root level or at the sinotubular level, early compared with late, in your echocardiographic follow-up data? If you could demonstrate that the diameters were the same both early and late, that would support your contention that the dilatation occurs due to leaflet changes rather than to natural dilatation.
DR JONES:Those are good points. We would hope that we would have that degree of accuracy to be able to measure it with echocardiography. Doctor Elkins certainly has been able to measure growth changes with the pulmonary autograft in children.
DR CHARLES R. BRIDGES (Jacksonville, FL):I enjoyed your presentation and have one question, which has a couple of subquestions associated with it. The incidence of endocarditis was surprisingly high in the infracoronary technique, and I was wondering if you could speculate on the reasons for that. In prosthetic valve replacement, as you know, the bacteriology of endocarditis differs from the bacteriology of endocarditis in native valve endocarditis. Specifically, there is a higher incidence of Staphylococcus epidermidis and Staphylococcus aureus endocarditis in prosthetic valves as opposed to a predominance of streptococcal species in native valves. I was wondering if that same difference in bacteriology applied to the endocarditis you observed in the infracoronary technique, and also if you could speculate on the difference in endocarditis incidence between the infracoronary and root replacement techniques.
DR JONES:To answer the last question first, I am not sure that we are able to answer that at the present time. It may be related to the mean length of follow-up. In the infracoronary implantations the mean length of follow-up was 54 months. The mean length of follow-up in the root replacements, a relatively newer method of implantation, was only 22 months. Many of these cases of endocarditis in the subcoronary implantation patients were late.
Let me address the first question, because I think it is extremely important. The use of the allograft at our institution was reserved for very few patients and what I thought was a very carefully controlled and selected group. The primary recipients of allograft implantation in the last 2 years have been those who are thought to be noncompliant with an anticoagulation regimen. I think that you know what this means socioeconomically. These patients are not your most reliable patients, are not patients who receive good dental prophylaxis, and also may be patients who may be more prone to endocarditis.
The other group of patients for whom the allograft is particularly attractive are candidates for transplantation. We had several patients who were renal transplant candidates, in whom anticoagulation was contraindicated before the procedure. In the 1 root patient who had endocarditis and required explantation, root abscess and endocarditis developed after renal dialysis. These patients are a real test for the allograft.
I might also point out that Mr Ross, when he first started doing the pulmonary autograft procedure, had an incidence of endocarditis that was very high in patients 18 years of age and younger. At first he had a 30% incidence of endocarditis. I think the incidence depends on the types of patients in whom you are implanting the valves. You can place them successfully in an infected environment, but they are not invulnerable to infections later.
DR RONALD C. ELKINS (Oklahoma City, OK):Doctor Jones, I compliment you on a very nice study. I do think that this certainly parallels the address of Mr Mark O'Brien, who recommends that a root replacement technique be used for the allograft aortic implantation. I think we all have to recognize that the allograft is a nonviable valve, it is inert tissue, and it appears to be relatively resistant to endocarditis. We have good long-term studies suggesting that it does not have the early phase of infection, but it is not necessarily going to solve the problem in the highest risk patients. I think whether you pick a prosthetic valve, a xenograft, or an allograft valve and put it in a large number of transplant patients, you are going to have endocarditis in those patients in a higher frequency than you would in the average group of patients who require aortic valve replacement. Nevertheless, I appreciate your providing this information. I think it is a very nice study.
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