Comparison of longitudinal elastic properties of proximal and distal strips of aorta-branch junctions from the abdominal aorta of sheep

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Abstract
Narrow longitudinal continuous strips were cut from the abdominal aorta and its major branches so that each strip contained the same width of aorta, bifurcation, and branch although the lengths of the three segments were different. A grid was marked on each region, and photographs made at a variety of strains as the whole strip was stretched at a strain rate of 2 cm/min with an Instron tensile testing machine. Measurements from the grids gave the strains for each region, and stress–strain curves were calculated. The proximal bifurcation zone was much more extensible than any of the other regions, owing mainly to changes in the "slack" of the collagen fibers (p < 0.01). This would imply that the shape and cross-sectional area of the bifurcation region are apt to change between diastole and systole, and implies that model studies which assume the shape of the bifurcation region is constant may not be accurate.