Longitudinal stress-strain relation of human peripheral vessels ex vivo

Qiang JIE; Liu YANG; Li ZHAO; Yaotian HUANG; Yunyu HU; Jue LI

ABSTRACT

BACKGROUND:

Due to the difference of species, the data of vessel in human are particularly useful for the clinical practice.

OBJECTIVE:

To analyze the longitudinal residue strain and the relationship between stress and strain of human limb arteries and veins, and explore the influence of different biomechanical properties on the repairs of limb injury.

DESIGN:

Observational trials.

SETTING:

Institute of Orthopaedics, Xijing Hospital of the Fourth Military Medical University of Chinese PLA.

PARTICIPANTS:

The experiment was carried out in the Xijing Hospital Affiliated to the Fourth Military Medical University of Chinese PLA from September 2005 to September 2006. The specimens were taken from 13 male amputee donors(who treated for accident injury), aged 18 to 30 years. Those tissue samples were used with the approval from the donors and offered by Xijing Hospital Affiliated to the Fourth Military Medical University of Chinese PLA.

METHODS:

①Harvest and preservation of samples The samples were obtained within 2 hours after death. The vessels were calibrated and harvested without any large branch to avoid the influence on the mechanical property of vessel wall,and then token on major vessels of limbs with Methylene Blue. The distance between the points token on vessel was measured by vernier caliper. The token vessels were cut and taken into Kreb's liquid in ice casement, then were kept into freezer (0-5 ℃). ②Longitudinal stretch ratio measurement The vessels were taken into Kreb's liquid and the distance between the points token on vessel was measured by vernier caliper. The longitudinal residue strain was expressed by longitudinal stretch ratio. Lab temperature was 20-25 ℃, experiment was finished in 2 hours after sampling.③Stretch test The vessel cut 1.0 cm was set into the instrument with Kreb's liquid for uniaxial tension test. The change length of each vascular specimen with or without the load and each load was measured three times and was averaged, lab temperature was 20-25 ℃, and experiments were finished in 5 hours after sampling. The curve of stress-strain was fitted by the measured data.MAIN OUTCOME

MEASURES:

Longitudinal stretching ratio, residue strain and stress-strain relationship of normal limb arteries and veins.

RESULTS:

The longitudinal stretch ratio of each artery decreased along vascular branch from proximal heart part to distal heart part, and that of each vein was contrast; There were significant difference in the longitudinal stretch ratios of major artery compared with those of saphena megna vein and branchiocephalicae vein (P ＜ 0.001). The curve of artery shifting right showed the stiffness of vessels decreased along vascular branch from proximal heart part to distal heart part. That of vein shifting left showed the stiffness of vessels increased along vascular branch.

CONCLUSION:

With the major artery of human limbs from proximal end to distal end, both the longitudinal residue strain and the vascular stiffness gradually decreases, as for the vein, the condition is contrast. It suggests that the longitudinal biomechanical property should be involved into the consideration of repairing the artery and vein injuries of different sites.