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J Thorac Cardiovasc Surg 2000;120:194-195
© 2000 The American Association for Thoracic Surgery

LETTERS TO THE EDITOR

Studies in thoracic aortic graft infections: The development of a porcine model and a comparison of collagen-impregnated Dacron grafts and cryopreserved allografts

Clinic for Cardiovascular Surgery, University Hospital, CH-8091 Zurich, Switzerland

To the Editor:

I enjoyed reading the animal study of thoracic aortic infections by Rowe and colleagues, ¹ in which they examined timing of graft inoculation with staphylococci and compared the resistance to infection between cryopreserved porcine allografts and collagen-impregnated Dacron grafts. They concluded that the high morbidity and mortality of prosthetic graft infections demands a search for improved methods of prevention and therapy. In addition, from their animal model, they believe that collagen-impregnated Dacron grafts were as good as and possibly superior to cryopreserved porcine allografts in resisting infections caused by bacteremia.

This experimental setting tested whether prosthetic graft inoculation in the presence of bacteremia leading to subsequent graft infection is better prevented by collagen-impregnated Dacron grafts or by cryopreserved porcine allografts. Thus, this has been a study of how to prevent infection and not how to treat cardiovascular infection. It does not have a relation to the surgical treatment of established native or prosthetic aortic infection when allografts are present. Prosthetic graft infection is a disastrous complication. However, results have markedly improved and operative mortality rates for major aortic infection have decreased to as low as 6% ² to 13.6%. ³ This improvement should be acknowledged by the authors. Moreover, the 30-day mortality for thoracic aortic graft infection has been nearly eliminated. ² Excellent survival free of reoperation is achieved when cryopreserved aortic allografts are used. In my opinion, the resistance to infection of cryopreserved vascular allografts is experimentally ^4,5 and clinically proven. However, these relevant studies ^2-5 were not referenced in this article.

Prevention of graft infection, as examined in this study, is quite a different topic. The use of allografts to treat established vascular infection must be accompanied by a simultaneous antibiotic treatment ⁴ to be effective, a point that is not considered in this study. Hence, I am not surprised that the authors conclude that cryopreserved porcine allografts are at least equivalent and possibly inferior to collagen-impregnated Dacron grafts in prevention of infection, because their study underestimated the importance of concomitant local and systemic antibiotic treatment at the time of allograft implantation. The suggestion that collagen-impregnated Dacron grafts may be more resistant to infection than cryopreserved allografts may be true for this porcine aortic model. Obviously, it does not correspond to the clinical results as mentioned. Therefore, recommendations cannot be made from this animal study regarding how to treat established vascular infection in the clinical setting. I further doubt that it was necessary (1) to demonstrate in animals the high mortality of untreated vascular graft infection (phase I), which is well known, and (2) to speculate about the resistance to infection of cryopreserved allografts (phase II), which is clinically proven to be safe, reproducible, and cost-effective.

12/8/105890 doi:10.1067/mtc.2000.105890

References

1. Rowe NM, Impellizzeri P, Vaynblat M, Lawson NM, Kim YD, Sierra M, et al. Studies in thoracic aortic graft infections: the development of a porcine model and a comparison of collagen-impregnated Dacron grafts and cryopreserved allografts. J Thorac Cardiovasc Surg 1999;118:857-65. [Abstract/Free Full Text]
   
2. Vogt PR, Brunner-LaRocca HP, Carrel T, von Segesser LK, Ruef C, Debatin J, et al. Cryopreserved arterial allografts in the treatment of major vascular infection: a comparison with conventional surgical techniques. J Thorac Cardiovasc Surg 1998;116:965-72. [Abstract/Free Full Text]
   
3. Chiesa R, Astore D, Piccolo G, Melissano G, Jannello A, Frigerio D, et al. Fresh and cryopreserved arterial homografts in the treatment of prosthetic graft infections: experience of the Italian Collaborative Vascular Homograft Group. Ann Vasc Surg 1998;12:457-62. [Medline]
   
4. Knosalla C, Goeau-Brissonniere O, Leflon V, Bruneval P, Eugene M, Pechere JC, et al. Treatment of vascular graft infection by in situ replacement with cryopreserved aortic allografts: an experimental study. J Vasc Surg 1998;27:689-98. [Medline]
   
5. Koskas F, Goeau-Brissonniere O, Nicolas MH, Bacourt F, Kieffer E. Arteries from human beings are less infectable by Staphylococcus aureus than polytetrafluoroethylene in an aortic dog model. J Vasc Surg 1996;23:472-6. [Medline]
   

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Paul R. Vogt Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Vogt, P. R. Search for Related Content PubMed PubMed Citation Articles by Vogt, P. R.