Arterial occlusive disease: a function of vessel bifurcation angle

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Fluid Dynamics

Background:

• Clinical observation suggests a link between aortoiliac occlusive disease and a high aortic bifurcation.
• Previous studies indicate variations in aortic bifurcation angles between patients with and without occlusive disease.

Purpose of the Study:

• To investigate the relationship between aortic bifurcation angle and shear stress.
• To explore the biomechanical factors contributing to atheroma formation in the aorta.

Main Methods:

• Analysis of 100 abdominal aortograms to measure aortic bifurcation angles.
• Construction of a flow visualization system using Pyrex models with varying bifurcation angles.
• Measurement of fluid velocity and calculation of shear stress at different flow rates.

Main Results:

• Patients with occlusive disease exhibited a significantly smaller average bifurcation angle (38 degrees) compared to those with normal or aneurysmal aortas (52 degrees).
• Experimental models showed that acute bifurcation angles increase shear stress on the inner wall and decrease it on the outer wall.

Conclusions:

• Acute aortic bifurcation angles may promote atheroma formation through altered shear stress patterns.
• Findings support theories linking both high and low shear stress to atheroma predilection in the aorta.