P191	Change of compliance of the allogenic vascular grafts implanted in infected environment.
1M.Gabriel, 1K.Wachal, 2K.Pawlaczyk, 1G.Oszkinis, 3A.Korcz
1Department of General and Vascular Surgery, Poznan University of Medical Sciences, Poznań, PL; 2Department of Hypertension and Vascular and Internal Diseases, Poznan University of Medical Sciences, Poznań, PL; 3Institute of Human Genetics, Polish Academy of Sciences, Poznań, PL.

Implantation of vascular allografts is one of the basic methods of vascular reconstruction following removal of infected grafts. Although their use diminishes the overall mortality and amputation rates however they may cause many complications related with functioning of the grafts in the late post-operative period. The aim of the work was to estimate the changes of the mechanical properties of vascular grafts implanted in infected environment. A group of 58 patients was studied. In 50 patients fresh allografts and in 8 patients cryopreserved allografts were implanted. In all patients with implanted allografts the analyses of mechanical properties of implanted vessels were performed with ultrasound scan with color coded Doppler and M-mode functions. Based on the results obtained from the second week to the 48 th month following implantation changes in the thickness of the wall, external and internal diameter, compliance, expansibility and Young module of the allografts were determined. The ultrasound examination of implanted grafts revealed gradual thickening of the IM complex, dilatation of the external diameter and stenosis of the internal diameter as well as the stiffening of the wall. The severity of these changes correlated with the intensity and duration of inflammatory reaction. Reconstruction of the vessel structure accompanying graft implantation relies on thickening of intima in result of migration and proliferation of myocytes and to a lesser extent fibroblasts; and on significant decrease in number of cells in the media and fibrination of adventitia. Conclusions:There is significant correlation between progress and severity of changes in the mechanical properties and prevalence of late complications in functioning of allografts. In the long-term follow-up in vivo conditions gradual thickening of the IM complex, dilatation of the external diameter and stenosis of the internal diameter as well as the significant loss of the elasticity of the grafts are the dominant changes in mechanical properties. The extent of these changes correlates with the intensity and duration of inflammatory reaction defined by the change in secretion of the acute phase proteins and in distribution of subpopulations of lymphocytes. Lower extent of elasticity changes was associated with weaker and shorter inflammatory reaction.

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