Steady flow analysis in the vicinity of an end-to-end anastomosis.

A study using both experimental and numerical methods was conducted to determine flow dynamics in the vicinity of an end-to-end anastomosis. In vitro experiments were performed to determine the variations in the conduit cross-section at the anastomosis in specimens under static loading. The experimentally determined geometries were used to simulate steady flow through an end-to-end anastomosis using the finite analytic (FA) numerical solution technique in order to obtain solutions for the governing axisymmetric laminar flow equations. Wall shear stresses in the vicinity of end-to-end anastomoses under steady flow conditions were measured using a flush-mounted hot-film anemometer (FMHFA) probe. The experimental measurements were in agreement with numerical results, except in flow with low Reynolds numbers. Wall shear stresses increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stresses were observed distal to the anastomosis. The present study suggests a correlation between regions of low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia (ANFH) in end-to-end anastomoses.