Axial flow fields in cuffed end-to-side anastomoses: Effect of angle and disease progression

Objective: to visualize the axial flow fields in standard and cuffed end-to -side anastomoses (ESA). Design: in vitro experiments using a flow rig, custom-built glass models an d frame-by-frame video analysis of flow patterns in standard and cuffed ESA . Subjects: glass models of standard or cuffed (1 cm or 2 cm high) ESA of ang les 15, 30, 45 and 60 degrees. Results: the cross-sectional area of standard ESA is much smaller than that of ESA between graft and cuff. The size of the vortex in the anastomotic z one of both standard and cuffed ESA increased with increasing ESA angle and cuff height, but did not change with flow rate. The presence of the vortex maintains a zone of flow separation and low shear at the heel of standard and graft/cuff anastomoses. Conclusions: the observations explain the clinical findings of intimal hype rplasia (IH) at the heel of PTFE/cuff anastomoses. The improved patency rat es of cuffed ESA may be due not to decreased IH, but to an increased abilit y of the cuff to accommodate IH before causing a significant stenosis.