THE ANASTOMOSIS ANGLE DOES CHANGE THE FLOW-FIELDS AT VASCULAR END-TO-SIDE ANASTOMOSES IN-VIVO

Purpose: The purpose of this article was to study the influence of the anastomosis angle on the how fields at end-to-side anastomoses in viv o. Methods: Polyurethane grafts of similar internal diameter to that o f the abdominal aorta (8 mm) were implanted from the suprarenal to the infrarenal level in 10 pigs. Three angles of standardized distal end- to-side anastomoses (90 degrees, 45 degrees, and 15 degrees) were stud ied. The anatomic position of the anastomoses was constant, the proxim al outflow segment was occluded, and the flow rate through the graft w as controlled. Flow visualization was accomplished by a color-how Dopp ler ultrasound system. Results: The angulation was reproduced within 1 0%. Gross hemodynamic parameters were stable, and the similarity param eters were typical for peripheral bypasses (mean Reynolds number is 42 4 and Womersley's parameter is 5.9). The flow fields were clearly depe ndent on the anastomosis angle. A zone of recirculation (approximately 5% of the flow area), extending from the toe to one diameter downstre am, was found in the 45-degree and 90-degree anastomoses. No flow dist urbances were detected at the toe and one diameter downstream with an anastomosis angle of 15 degrees. At the heel different recirculating f low patterns were found in the different anastomoses. Conclusion: The anastomosis angle does change the how fields at vascular end-to-side a nastomoses in vivo.