Forty-two anastomotic
aneurysms were encountered in 33 patients over a 13-year period. Thirty-six occurred after the use of
prostheses, and six occurred after the the use of vein grafts. In the prosthetic group, 28 aneurysmal defects were repaired, and the cause was found in 25 cases. In 23 of these cases the defect was caused by the
sutures that had pulled out of the arterial wall;
suture failure was recorded in only two cases. There were no defects in any of the
prostheses. The
suture material was braided
Dacron (
Tevdek) in 25 anastomotic
aneurysms, but it was not recorded in three cases. In the vein graft-related group the
aneurysms occurred in the "juxta anastomotic position," with the
suture lines intact. They were thus true
aneurysms of the vein wall. This study shows that the predominant cause of an anastomotic
aneurysm in weakness of the arterial wall and not the mechanical failure of the
suture material (braided
Dacron) or
prosthesis. It would seem, however, that the
prosthesis, by virtue of its undesirable physical characteristics-a compliant mismatch with the host artery and some dilatation with the passage of time-results in abnormal shear stress at the anastomosis, leading to disruption of the arterial wall and eventually to
false aneurysm formation.