Abstract
We experimentally evaluated diode laser welding between the vessel and artificial graft by tension/strain characteristics. We used extracted fresh porcine coronary artery strip, which the intima was removed intentionally, and collagen-coated knitted dacron. graft (Hemashield). An 830nm diode laser (power density, 57W/cm2) was employed to make welding with contact irradiation method, after topical application of indocyanine green dye (peak absorption, 805nm) and compression (3.5kg/cm2) of irradiation spot. The laser irradiation time was 30s in all. The specimens were strained axially until ultimate breakage occured in order to draw a stress-strain profile graph. We compared welded vessel-graft tissue group with welded vessel-vessel tissue group. Welded vessel-graft tissue (27.9±1.9g/mm2, n=10) withstood significantly higher stress(p<0.01) than welded vessel-vessel tissue (17.1±1.9g/mm2, n=10). No significant differences in strain limits of Hook's law, which was relative length until Hook's law could not be applied, were noted between welded vessel-graft tissue group and welded vessel-vessel tissue group. We obtained Young's modulus from a stress-strain profile graph. There was the significant difference in Young's modulus between the two groups (1.24±0.09×106dyn/cm2vs. 2.29±0.22×106dyn/cm2, n=10, p<0.05). And then, histrogical study of welded vessel-graft tissue showed that the vascular collagen fibers melted and invaded into fibers of the knitted dacron graft on the irradiation spot.
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