Effects of anastomotic angle on vascular tissue responses at end-to-side arterial grafts.
OBJECTIVE
Hemodynamics has been implicated in the late failure of arterial bypass grafts, which frequently occurs at the distal anastomosis site. This study was designed to assess the relationship between local hemodynamics and pathologic responses of the distal anastomosis by manipulation of the angle of anastomosis of the graft, a major determinant of local hemodynamics.


METHODS
End-to-side anastomoses of the right carotid to the left carotid arteries of rabbits were performed at anastomotic angles of less than 10 degrees (acute), 45 degrees (intermediate), or 90 degrees (right angle), and then the upstream left carotid arteries were ligated to simulate pathologic occlusion. We examined tissue responses on the wall of the recipient vessel opposite the anastomosis site (the bed), where unusual hemodynamic forces are imposed.


RESULTS
Three months after surgery, intimal thickening was observed on the upstream portion of the acute, and more rarely, the intermediate anastomoses only. Medial thinning caused by loss of cells and matrix, and an aneurysm-like dilation, was observed in the right angle and some intermediate anastomoses, but not in the acute anastomoses. En face confocal microscopy at 3 weeks after surgery revealed severe disruption of the internal elastic lamina in all anastomotic models. Zymography and Western immunoblotting demonstrated gelatinolytic activity, caused by expression and activation of MMP-2, that was lowest in the acute anastomoses, higher in the intermediate anastomoses, and highest in the right-angle anastomoses.


CONCLUSIONS
We infer that very different pathologic changes to the vessel wall are elicited when local hemodynamics is manipulated by altering the anastomotic branch angle.
Jackson
Z S
ZS
Department of Laboratory Medicine and Pathobiology, University of Toronto, and the Toronto General Research Institute, Ontario, Canada.
Ishibashi
H
H
Gotlieb
A I
AI
Langille
B L
BL
D000714:Anastomosis, Surgical / Q000379:methods*; D000818:Animals; D001158:Arteries / Q000502:physiology* / Q000637:transplantation*; D006439:Hemodynamics; D008297:Male; D008433:Mathematics; D011817:Rabbits; D014656:Vascular Surgical Procedures / Q000379:methods