*2.3.3 Measurement of hoop stress modulus*

For the direct measurement of hoop stress elastic modulus, strips 10 mm in width were cut from the proximal end of each test aorta using a guillotine-guide which compressed and held the artery between two plates of Perspex provided with cutting slots, and measurement of stress/strain relationships was undertaken at stresses of between 0 and 100mN/mm2 at 0.2 N intervals using the tensiometer device illustrated in **Figure 4**. Either end of each hoop was firmly held between two aluminium blocks lined with fine sandpaper that were screwed together and then


**Table 1.**

*Range of machine settings and direct and derived variables measured.*

*Role of Arterial Pressure, Wall Stiffness, Pulse Pressure and Waveform in Arterial Wall… DOI: http://dx.doi.org/10.5772/intechopen.100048*

**Figure 4.**

*Tensiometer apparatus for measurement of stress/strain relationship of aortic hoop strips.*

attached with magnets to the tensiometer once the hoop strip was mounted. Two points about 4 cm apart were marked at the upper and lower extremity of each hoop with Gentian Violet and the laser was then used to project the relative position of these marks onto a scale as the progressive loads were applied. The average cross sectional area of each hoop was calculated by measuring the width and thickness of the arterial strip with a micrometer at three positions in the middle and at the junction of the central and upper and lower thirds at the beginning and end of each test, and taking the mean.
