An in vivo model for studying the local haemodynamics of end-to-side anastomoses.

Abstract

To develop an in-vivo model to study the anastomotic flow patterns. Prospective, open, animal study. Polyurethane grafts with an internal diameter equal to the abdominal aorta (8 mm) of 90 kg pigs were implanted as bypass grafts from the supra-renal to the infra-renal level. A novel technique for constructing anastomoses with different anastomosis angles and only slight dilatation was used. The proximal outflow segment was occluded and the flow rate through the graft controlled by clamping the iliac arteries. Visualisation of the flow-fields at the distal end-to-side anastomosis was achieved by a comprehensive colour Doppler mapping protocol. The angulation of the anastomoses was controllable and reproducible. Gross haemodynamic parameters were stable within physiological ranges and were typical for peripheral bypass grafts. The flow fields at the distal end-to-side anastomosis were visualised and found to be in accordance with those reported by in vitro studies. Using different angles of Doppler insonation the same flow field characteristics were found. The model is an appropriate tool for studies of the effects of anastomotic geometry on local flow fields in vivo.