  In this paper, the objective is to assess the histomechanical effects of
collagen proteolysis in arteries under loading conditions reproducing in vivo
environment. Thirteen segments of common porcine carotid arteries (8 proximal
and 5 distal) were immersed in a bath of bacterial collagenase and tested with
a pulsatile tension/inflation machine. Diameter, pressure and axial load were
monitored throughout the tests and used to derive the stress-stretch curves and
to determine the secant circumferential stiffness. Results were analyzed
separately for proximal and distal segments, before and after 1, 2 and 3 hours
of enzymatic degradation. A histological analysis was performed to relate the
arterial microstructure to its mechanical behavior under collagen proteolysis.
Control (before enzymatic degradation) and treated populations (after 1, 2 or 3
hours of enzymatic degradation) were found statistically incomparable, and
histology confirmed the alteration of the fibrous structure of collagen bundles
induced by the collagenase treatment. A decrease of the secant circumferential
stiffness of the arterial wall was noticed mostly at the beginning of the
treatment, and was less pronounced after 1 hour. These results constitute an
important set of enzymatically damaged arteries that can be used to validate
biomechanical computational models correlating structure and properties of
blood vessels.
