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Ann Thorac Surg 1997;64:1421
© 1997 The Society of Thoracic Surgeons
DR CONSTANTINE MAVROUDIS (Chicago, IL): Doctor Jakob and his colleagues are to be congratulated on a significant contribution to the treatment of long-segment tracheomalacia. Their methods are carefully planned, and their data are clear and are well presented. My colleagues and I also agree with their use of cardiopulmonary bypass to achieve proper exposure and stability for the operation.
External tracheal stenting is not new and has been successfully used for the innominate artery compression syndrome as well as an adjunct to pericardial patch tracheoplasty and repair of tetralogy of Fallot with absent pulmonary valve. However, the idea of circumferential PTFE external stenting, as used by Dr Jakob and his associates, represents an ingenious step forward for these very difficult cases.
My colleagues, Carl Backer and Lauren Hollinger, and I have used a slightly different therapeutic approach to achieve internal stabilization by placement of Palmaz stents, which are expandable. Our experience includes 6 ventilator-dependent patients who had persistent long-segment bronchotracheomalacia after tracheoplasty in 5 and repair of tetralogy of Fallot with absent pulmonary valve in 1.
A total of 10 stents were used in 6 patients with good short-term results. One patient had a single ventricle and died of endocarditis, and another patient required stent removal and tracheostomy for control of his airway.
The Palmaz stent is deployed and expanded by bronchoscopic and fluoroscopic visualization. Repeated elective balloon dilations can be performed as necessary during somatic growth.
Of course, all these patients will require close follow-up to determine the best form of therapy. One advantage of external stenting is no tracheal incision, which limits the amount of intraluminal granulation tissue. Another plus is the theoretical potential for growth to adult proportions because of the oversizing of the PTFE. The advantages of the Palmaz stents are that they are easily deployed without thoracotomy and have the theoretical advantage of repeatable dilations to achieve adult size.
I have a few questions: What type of fluid or tissue do you anticipate will fill the space between the outer wall of the trachea and the inner wall of the PTFE stent? Do you think that this process might retard lateral tracheal growth for the future? Do you foresee using a biologically degradable external stent, which could be absorbed after the bronchotracheal tree stiffens during the natural process, which is known to occur?
I enjoyed the paper very much. Thank you very much for allowing me the privilege of discussing this important paper.
DR HERMES C. GRILLO (Boston, MA): I enjoyed hearing this ingenious and imaginative approach to a very rare but very difficult problem.
In the patients who died, and fortunately there were only a couple, did you have an opportunity to look at the ingrowth of connective tissue or its relationship to the PTFE? In the Nissen-Herzog type of posterior stabilization of the adult kind of malacia that you see with chronic obstructive pulmonary disease, we gave up PTFE because in a couple of patients the membranous wall and the PTFE eventually separated and fluid collected between them. This was because there generally is no tissue ingrowth into PTFE; in fact, there is not meant to be. Although you apparently did not have this problem here, I think it is a looming possibility.
You addressed the question of growth, which always is a problem in children. The adult trachea is so much larger, and the size and shape so different from that of small children, the question of accommodation in the future is one of concern. Will the patients have to live with a relative stenosis in adult life, or is there another approach? And, of course, external splinting versus internal splinting is related to an attempt to cure the problem rather than provide temporary palliation, which has to be adjusted with growth.
Finally, I have a comment that relates to the fact that there will be a temptation to use this method in adults. In adults, malacia that follows intubation injury is usually handled best by resection. Idiopathic malacia of the whole trachea, where the cartilages are gone, is extraordinarily rare in adults, and has been treated by external ring splints or in lying T tubes. The cases that are most commonly seen, where the cartilages actually retain structure but are deformed in an archer's bow configuration, and where the membranous wall is elongated, are best corrected by posterior splinting using appropriate materials, such as Marlex mesh. Thank you very much.
DR JAKOB: I thank the discussants for their kind remarks. Doctor Mavroudis and his department are well known to us, having a tremendous experience with this pediatric age group. He was addressing the question of implanting Palmaz stents for this type of tracheomalacia. We personally do not have experience with that, but do have some concern in regard to the growing organism with the delicate mucosa being injured by the constant pressure of a stent. In addition, we are afraid of possible migration or repeated exchanges necessary, meaning some additional costs have to be taken into consideration as well.
In regard to Dr Mavroudis' question of which kind of tissue we do expect between the PTFE prosthesis and the resuspended trachea, we cannot answer that definitely. The imaging techniques used so far do not allow us to specify if it is firm, fibrotic tissue or not. Maybe we have to use magnetic resonance scanning or other methods in the future to say anything about this kind of tissue.
Whether or not biodegradable material could become an external splint will be shown in the future. Thus far we have not seen a problem with the oversizing of the pediatric trachea, which resulted in a mean anteroposterior diameter of 1.1 cm and a transverse diameter of 1.3 cm in 4 children. This means that almost an adult-sized tracheal dimension has resulted. We do not expect problems in the future having this stiff material outside. But if a problem is encountered, of course, the PTFE prosthesis could be removed.
Doctor Grillo asked if we had a chance to study this unfortunate child who died. The child died some 100 km from Heidelberg, and, unfortunately, we did not know anything about it until we received a letter way after autopsy. The only thing we were told was that the trachea was widely patent, so no information was available about if there was fluid buildup between the trachea and the prosthesis.
The question of growth already was addressed with my remarks regarding the oversizing of the prosthesis.
Related Article
Ann. Thorac. Surg. 1997 64: 1412-1420.
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