CHANGING ETIOLOGY OF ANASTOMOTIC ANEURYSMS

Anastomotic aneurysms continue to occur in spite of the use of nonabsorbable suture material, improved grafts and surgical technique. The femoral anastomosis appears to be the site most predisposed to anastomotic aneurysms, and in the absence of infection, was previously explained on the basis of excessive longitudinal graft tension. There appear to be other factors operating which may be more important in producing mechanical stresses than those previously implicated. It is a commonly recognized principle that the union of 2 materials with different physical properties will be a ssociated with the generation of particular shear stresses which may be subsequently responsible for the disruption of anastomoses. With the currently available stiff prostheses, there does not appear to be any simple way of overcoming this problem. Increasing attention should be applied to developing grafts with physical properties similar to autogenous tissue. In addition, any disturbance in flow in the region of the anastomosis may be associated with the generation of vibratory forces in the wall which could lead to degeneration in elastin in the arterial wall with subsequent dilatation and weakening. This in itself may lead to complete disruption and anastomotic aneurysm formation. In an effort to prevent this problem, anastomoses in the femoral artery should be performed over a long segment to insure the maintenance of optimum flow characteristics in the region. Finally, infection appears to be a common underlying cause in what initially seems to be bland anastomotic aneurysms. In view of the fact that the femoral exposure is the most prone to the development of infectious complications, it is not surprising to find that this may be a major cause of the subsequent complication of anastomotic aneurysm. Whether the use of prophylactic antibiotics in these patients will reduce the incidence will be of interest to follow, but even this should not prevent the surgeon from the use of meticulous surgical techniques within this area.