Nonlinear analysis of arterial oscillated flow in experimental stenosis and microsurgical anastomosis

Background. Thrombotic vascular occlusion is of the main complications that can occur during microsurgical anastomosis and is frequent when the blood becomes turbulent. The aim of this ex vivo study was to test the use of non linear mathematical tools to detect turbulence how upstream and downstream of an arterial stenosis and of a microsurgical anastomosis technique in art eries with diameters in the range of microsurgical practice. Materials and methods. Rat carotid arteries (0.8 to 1.2 mm diameter) were t ransferred to a flow chamber and perfused with Krebs solution. An oscillate d vascular flow was initiated with a peristaltic pump and a transit time fl owmeter was used to measure flow with two probes. An arterial stenosis was created by a ligature and progressively increased ranging from 0 to 95%. Fo r each flow signal three nonlinear analytical procedures were applied: time -delayed procedures, correlation dimension, and computing of the largest Ly apunov exponent. Results. Our results indicated that the level of turbulence how is correlat ed with the area reduction stenosis. In the range of 60-95% area reduction stenosis, we noted an experimental increase of turbulence flow. We also fou nded that a classical end-to-end anastomosis technique induced an increase of the turbulence flow in comparison with a control artery. Conclusions. Thus nonlinear analysis can be useful in characterizing the co mplexity of an oscillated flow in small arteries submitted to stenosis or m icrosurgical anastomosis and may have clinical uses in detecting high level turbulent flow after microsurgery. (C) 2001 Academic Press.