Is the sclerotic vessel wall really more rigid than the normal one?

Quasistatic passive mechanical properties of fibrosclerotic and normal human anterior cerebral arteries were studied in vitro. Mechanical properties were characterized by incremental elastic modulus, strain energy density and incremental distensibility for a 20--250 mm Hg intraluminal pressure range. Fibrotic arteries were found to have a 34--45% lower elastic modulus at the same pressure levels than normal ones (p less than 0.01--0.02). Distensibility however proved to be only 28--35% higher in the fibrotic group, this difference was significant just at a few pressure values above 120 mm Hg. This was due to the opposite changes in elastic properties and radius to wall thickness ratio. It is supposed that higher elasticity of the fibrotic arterial wall is the consequence of a local compensatory process tending to prevent pathological alterations in distensibility of the arteries.