Detection of hemodynamic turbulence in experimental stenosis: an in vivo study in the rat carotid artery.

In a previous study, we have demonstrated that turbulences in arteries less than 1.5 mm in diameter perfused ex vivo by an oscillated flow can be determined using nonlinear mathematical models. The hypothesis tested here was that nonlinear analyses enable the in vivo detection of turbulences in blood flow in vessels with dimensions affected by microsurgery. Twenty Wistar male rats were studied. After an intraperitoneal anesthesia (50 mg/kg sodium pentobarbital), each right carotid artery was dissected and a transit time flowmeter was used to measure blood flow. Arteries were studied in control conditions and graded stenoses, which were performed by a collar system and progressively increased from 0 to 95%. For each flow signal, time delay, false-nearest neighbors, correlation dimension and the largest Lyapunov exponent were computed to characterize the level of turbulence. The level of turbulence was highly correlated with the degree of stenosis induced (p < 0.001). The correlation dimensions of all the flow signals varied between 3 and 5, thus implying that more than three independent noninteger control variables were necessary to account for the complexity of rat carotid artery dynamics. Turbulence flow significantly increased in arteries with 40-95% stenosis. Nonlinear analysis may be useful to determine the turbulence level of an in vivo flow in arteries less than 1.5 mm in diameter and might be clinical useful for turbulence detection after microsurgery. Copyright 2002 S. Karger AG, Basel