Small-diameter compliant arterial graft prosthesis: Design concept of coaxial double tubular graft and its fabrication

To minimize compliance mismatch between native artery and arterial graft pr osthesis over the entire pressure regions, we proposed a coaxial double tub ular artificial graft which consists of an enhanced compliant inner tube an d a less compliant outer tube, both of which were fabricated using well-con trolled multiply micropored segmented polyurethane (SPU) films. Double tubu lar grafts were coaxially assembled by inserting the inner tube into the ou ter tube. First, the pressure-diameter (P-D) relationship of canine common carotid arteries, which exhibited a "J" curve, was determined as a targeted artery. Two determinant variables, the pressure-induced distensibility of each tube and the intertubular space distance, were defined and formulated in several models of coaxial double tubular SPU grafts, which had various i ntertubular space distances, micropore densities, and wall thicknesses. The distensibility of the inner tube determined the distensibility in the low- pressure regions, which was adjusted using wall thickness and microporosity . Thinner films with higher porosities resulted in a high pressure-induced distensibility. On the other hand, a low pressure-induced distensibility in the high-pressure regions was realized using an outer tube with a thicker wall and lower microporosity. The transition point from low- to high-pressu re regions was determined by the intertubular distance using the theoretica l values. On the basis of these results, we presented a prototype model of a coaxial double tubular graft that exhibited well-matched compliance with canine carotid artery. (C) 2001 John Wiley & Sons, Inc.