OBJECTIVE

To assess deformation and displacement of vascular wall before and after abdominal aortic aneurysm stenting.

MATERIAL AND METHODS

There were 12 patients (mean age 63.2±6 years) with abdominal aortic aneurysm. Anatomical dimensions of aneurysm were evaluated according to CT data. Ultrasound examination was performed using 3.5—5.0 MHz linear sensor (Vivid 7, GE, USA). We analyzed images and blood flow velocity in abdominal aorta (middle part of aneurysm) and aortic bifurcation. Blood pressure was measured invasively in the same areas. Repeated registration of blood flow velocity and pressure was performed immediately after stenting. Analysis of data was performed using Ansys Workbench 19.2 and MultiVox software.

RESULTS

Considering anatomy and profile of blood flow, shear stress and elasticity of vascular wall, we analyzed quantitative indicators of vascular wall mechanics, as well as the effect of aneurysm asymmetry and wall thickness heterogeneity on peak stress. Aortic wall deformation was evaluated considering modeling data to determine the risk of complications in vascular wall pathology. Retrograde blood flow in aneurysm was due to malleability of arterial wall and aortic enlargement. Interaction of vascular wall, blood flow and pressure determines the stress that characterizes vascular strength against rupture. We determined 2 areas with distinct shear stress patterns in abdominal aortic aneurysm. Proximal flow is characterized by fluctuations with low average values. In distal aorta, flows merge that leads to turbulence with large negative values of vascular wall tension.

CONCLUSION

Stress distribution and changes of wall shear vector within the aneurysm influence structural integrity of vascular wall. These features are important for progression of disease. Low peak values of wall shear stress are interpreted as characteristic signs of further rupture.