Damage Analysis by Elongation of Blood Vessels

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The device was designed to analyze the damages to blood vessels while elongating beyond its physiological limits. It consists of a stepping motor, pulse generator, leaf spring and data transmission. Elongating speed is controlled by either constant or accelerated. A non-traumatic grasping forceps was used to fix at each end of a vessel. For purpose of data collections of uniform samples, rectangular materials (10 x 4 mm) of aorta of rabbits were trimmed with the longitudinal or horizontal direction of it, and set and pulled. Strain-stress curves during vessel elongations showed a certain pattern even though they appeared to have a large degree of dispersions. The values of stress increased slowly after starting elongation (the first stage), and then increases of stress raised sharply (the second stage). After reaching a peak, the values of stress decreased (the third stage). The first stage would show the normal physiological phase of extension and shrinkage that normal vessels have, and the second stage would show own characteristics of each vessel. And the third stage was destructive one. After improper materials were eliminated, the values of stress and strain were statistically compared between materials of longitudinal and horizontal direction. The similar tendency was obtained from a fixed speed (40mm/mm) and an acceleration (0.000467m/s^2). In this study, we established how to analyze disruption of the ^*large-sized arteries while elongating, however, in case of the median-sized arteries like vertebral arteries, further improvement of the grasping pars is needed.