Flow through the carotid artery — model for atherogenesis

The influence of blood flow on the depositions on the vessel wall has been observed and described already in 19th century. Further observations have shown correlation between certain forms of blood flow — recirculations, separated and stagnant flow — and wall alterations. These flow phenomena take places in the vessel bifurcations or bends. One of the vessel bifurcations, a carotid bifurcation, is well known as an artery, where the atherosclerotic process occurs often. However, the exact correlation between vessel geometry, flow parameters and wall alterations is not yet known. The goal of our project is the simultaneous investigation all of these parameters. The steps are as follows (please, click on the image to pop-up enlarged images):

1. The vessel casts from the cadaver arteries are produced in apparatus especially designed for this goal. The used material is the cast polymer Technovit.

The photo of the vessel cast of the human carotid bifurcation.

Vessel cast

Device for the fabrication of the vessel casts. It permits the generation of transmural pressure by applying a hydrostatic pressure to the external of the vessel. First, the external pressure is set to be positive to empty the vessel and prepares it for the filling with the liquid polymer. Once this is poured into the funnel, the pressure external to the vessel is set negative and the liquid polymer fills the vessel without air inclusion at a defined transmural pressure.

Fabrication device

2. The arteries are analyzed pathomorphological and morphometrical. The analysis follows the rules described in 1958 by the World Health Organization (WHO) group of experts on atherosclerosis. The location of the wall alterations and their level are represented in form of planar mapping.

The results of pathomorphometrical analysis in form of planar mapping show the distribution and alteration level of the atherosclerotic lesions in three human carotid bifurcations.

Atherosclerotic lesions

3. The vessel casts are used for the assessment of some geometrical parameters and for the fabrication of the three-dimensional computer phantoms of the vessels. The casts are digitized with help of optical computer-aided method for 3D measurement and modelling.

The silhouette of the common carotid bifurcations show large variations in the geometry of carotid bifurcation.

Geometric variations

4. The computation of the blood flow is performed with a Computational Fluid Dynamics (CFD) program FLUENT. An example for the computation of the shear stress at the wall is shown here.
5. The flow in the carotid artery was also analyzed by Digital Particle Image Velocimetry (DPIV). The results can be found here.

See subchapter for new data sets with digitized geometries and some additional information for respective vessel of the carotid bifurcations in JPEG-files. It includes:

• results of the pathological study
• geometrical parameters
• age and sex of the object
• main disease and direct cause of death