Flow visualization analysis in a model of artery-graft anastomosis.

Flow characteristics near the end-to-end anastomosis of vascular graft were studied in model tubes by flow visualization techniques. Artery and vascular graft were modelled by an elastic tube fabricated from an elastomeric polymer and a rigid plastic tube, respectively. Anastomotic models were made by connecting these two tubes, which had compliance mismatch at their anastomoses. These model tubes were installed into a mock circulatory loop and flow was visualized using hydrogen bubbles and aluminum powder as the tracer. Flow disturbances including flow separation and eddies were observed near the modelled distal anastomosis (graft-to-artery anastomosis). Peak values of the wall shear rate were high in the proximal anastomotic area (artery-to-graft anastomosis) and low in the distal region. These phenomena were enhanced in the models with increased compliance mismatch. The local abnormal flow observed in the anastomotic zone might cause thrombus formation and subintimal hyperplasia. To improve the patency in small-calibered arterial grafts, it is important to match their compliance to that of natural arteries.