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

Thrombotic vascular occlusion is one 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 nonlinear mathematical tools to detect turbulence flow upstream and downstream of an arterial stenosis and of a microsurgical anastomosis technique in arteries with diameters in the range of microsurgical practice.

Rat carotid arteries (0.8 to 1.2 mm diameter) were transferred to a flow chamber and perfused with Krebs solution. An oscillated vascular flow was initiated with a peristaltic pump and a transit time flowmeter was used to measure flow with two probes. An arterial stenosis was created by a ligature and progressively increased ranging from 0 to 95%. For each flow signal three nonlinear analytical procedures were applied: time-delayed procedures, correlation dimension, and computing of the largest Lyapunov exponent.

Our results indicated that the level of turbulence flow is correlated with the area reduction stenosis. In the range of 60-95% area reduction stenosis, we noted an experimental increase of turbulence flow. We also founded that a classical end-to-end anastomosis technique induced an increase of the turbulence flow in comparison with a control artery.

Thus nonlinear analysis can be useful in characterizing the complexity of an oscillated flow in small arteries submitted to stenosis or microsurgical anastomosis and may have clinical uses in detecting high level turbulent flow after microsurgery.