Effect of Wall Structures on Mechanical Properties of Small Caliber PHBHHx Vascular Grafts

Abstract

In order to analyze the effect of vascular wall structures on static and dynamic mechanical properties of vascular grafts, small calibre PHBHHx (Poly(3-hydroxybutyrate-co-3-hydroxhexanoate)) vascular grafts (inner diameter 6 mm) with various wall shapes and thicknesses were fabricated by changing electrospinning time and receiving molds. As spinning time increased, wall thickness of the vascular grafts increased and both circumferential tensile strength and suture retention strength improved significantly. When the wall thicknesses of straight grafts were about 120 μm, the great radial dynamic compliance was exhibited, however, the tensile strength and suture retention strength of the straight tubes can’t reach the requirements of normal blood vessel grafting. With the wall thicknesses increasing above 250 μm, although the circumferential tensile strength and suture retention strength gradually achieved the transplanting requirements, the dynamic compliance of the straight tubes declined too sharply to adapt the blood radial shock. For corrugated grafts, the effect of wall thickness on radial dynamic compliance was little, and the radial dynamic compliance was close to that of the commercial vascular grafts. The circumferential tensile strength and suture retention strength of the corrugated grafts were also improved to approach the commercial vessels’ performances with the wall thickness improving to about 425 μm. Elastic recovery rates of all the prepared vascular grafts were superior to that of the commercial sample. Along with the wall thickness exceeding 250 μm, the water permeabilities of both the straight and the corrugated grafts were less than 300 ml/(cm²·min).