Bleeding and infec
Bleeding and infection
Bleeding and infection are the earliest but the least – reported causes of failure . Bleeding occurs either of the suture line or through the interstices of the graft , it is common to encounter bleeding at the suture lines in woven grafts ,this is an inherent feature of these grafts because suturing creates holes in the graft that will not close naturally as is know to happen in the more compliant knitted –fabric grafts . It is rare to find bleeding through the interstices of woven grafts because of their relative tightness of structure and consequent low porosity, whereas it is common to find bleeding through the interstices of knitted –fabric grafts because of their higher porosity .Pre-clotting is essential for these prostheses and usually results in sealing the pores effectively in highly porous knitted fabric grafts , pre-clotting would be extremely difficult and infective for this reason, all knitted –fabric- grafts under-go compaction to reduce their porosity further on the other hand tightly knitted grafts of low porosity are also difficult to pre-clot , too high or too low a porosity can create difficulties in pre-clotting and may result in bleeding. The late failures are not solely associated with bleeding through the interstices of the grafts , they are probably also caused by bleeding through rupture tears and slits of the grafts in which bleeding is not cause of failure but its out come infection is the rarest cause of graft failure, the actuel incidence of infection is believed to be significantly greater.(113) It is evident that several different complications may occur at various stages in the life of the prostheses , The development of infection –resistant graft by means of drug –delivery systems is beginning to receive some attention
The work in this area may be categorized as :
a- promotion of full-wall healing and
b-development of anti -thrombogenic surface.
the development of an anti - thrombogenic surface may or may not lead to full-wall healing .
A mesh tube made of polyglactin suture material has been inserted into a PTFE tube, although the inner surface was apparently covered by endothelialized tissue , this design is not believed to promote full wall healing, since the micro porous structure of the PTEF would not appear to permit penetration of the tissue through the wall .
