[The Dacron vascular prosthesis in men. Mechanical performance, lesions and molecular stability]. / Prothèses vasculaires en Dacron chez l'homme. Performances mécaniques, lésions et stabilité moléculaire.

The causes of failure of vascular prostheses implanted in man were investigated by means of histological, ultrastructural and scanning electron microscopic techniques as well as mechanical performance and macromolecular structure studies. These investigations concerned 22 out of 212 explanted prostheses from about 10 vascular surgery departments, examined over a 3-year period. The changes observed in the mechanical properties of the explanted prostheses (2 to 75 per cent reduction of resistance to rupture) and the finding of broken fibers and migrating polyester particles were confirmed by the presence of structural alterations in the polymer with, in particular, diminution of its crystalline structure. No correlation was found between the occurrence of these lesions and the type of prosthesis used and/or the duration of implantation.

Long-term results of arterial allograft below-knee bypass grafts for limb salvage: a retrospective multicenter study.

PURPOSE: Arterial allografts (AAs) have been recently reconsidered in the treatment of critical limb ischemia when vein material is absent, because of the disappointing results with artificial grafts. The aim of this study was to report the results observed in three centers where AAs were used for infrainguinal reconstruction in limb-threatening ischemia. METHODS: Between 1991 and 1997, 165 AA bypass procedures were performed in 148 patients (male, 90) with a mean age of 70 years (range, 20-93 years). Indications for operation were rest pain in 54 cases and tissue loss in 111 cases. Mean resting ankle pressure was 53 mm Hg in 96 patients who did not have diabetes and mean transcutaneous pressure of oxygen was 10 mm Hg in 52 patients who did have diabetes. In 123 cases (75%), there was at least one previous revascularization on the same limb. AAs were obtained from cadaveric donors. The distal anastomosis was to the below-knee popliteal artery in 34 cases, to a tibial artery in 114 cases, and to a pedal artery in 17 cases. RESULTS: At 30 days, the mortality rate was 3.4%; the primary patency rate was 83.3%; the secondary patency rate was 90%; and the limb salvage rate was 98%. During follow-up (mean, 31 months), 65 grafts failed primarily. Causes of primary failure were thought to be progression of the distal disease in 15 cases, myointimal hyperplasia in 16 cases, graft degradation in 10 cases (four dilations, three stenoses, two ruptures, and one dissection), miscellaneous in eight cases, and not known in 16 cases. Primary patency rates at 1, 3, and 5 years were, respectively, 48.7% +/- 4%, 34.9% +/- 6%, and 16.1% +/- 7%. Secondary patency rates at 1, 3, and 5 years were, respectively, 59. 8% +/- 4%, 42.1% +/- 5%, and 25.9% +/- 8%. Limb salvage rates at 1, 3, and 5 years were, respectively, 83.8% +/- 3%, 76.4% +/- 5%, and 74.2 % +/- 8%. CONCLUSION: AA leads to an acceptable limb salvage rate but poor patency rates. A randomized trial that will compare AAs and polytetrafluoroethylene should be undertaken.

Stability of performances of vascular prostheses retrospective study of 22 cases of human implanted prostheses.

Twenty-two cases of vascular graft failures (thrombosis, pseudoaneurysm, dilation, infection) were investigated by means of physicochemical, histological, and ultrastructural studies. A general decrease of mechanical resistance to stress of the prostheses was observed. Its magnitude ranged from 2 to 75% of the values of identical virgin prostheses and there was no relation with the duration of implantation. In addition to the breakage of yarn filaments (SEM), migration of fiber debris (histology) was observed in 7 cases. The structure of the polyester molecule had evolved after implantation. A decrease of crystallinity (x-ray diffraction and differential scanning calorimetry) was noted. These observations raise the question of the established stability of vascular prostheses and emphasize the need for further investigations in human graft retrieval programs.