Compliance properties of conduits used in vascular reconstruction

Background: Compliance mismatch between native artery and prosthetic graft used for infrainguinal bypass is implicated in the aetiology of graft failu re. The aim was to quantify the elastic properties of a new compliant poly( carbonate)polyurethane (CPU) vascular graft, and to compare the compliance properties of grafts made from CPU, expanded polytetrafluoroethylene (ePTFE ), Dacron and human saphenous vein with that of human muscular artery. Methods: A pulsatile flow phantom was used to perfuse vessel and prosthetic graft segments at physiological pulse pressure and flow. Intraluminal pres sure was measured using a Millar Mikro-tip catheter transducer and vessel w all motion was determined with duplex ultrasonography using an echo-locked wall-tracking system. Diametrical compliance and a stiffness index were the n calculated for each type of conduit over mean pressures ranging from 30 t o 100 mmHg by 10-mmHg increments. Results: The compliance values of CPU and artery (mean over the pressure ra nge) were similar (mean(s.d.) 8.1(0.4) and 8.0(5.9) per cent per mmHg x 10( -2) respectively), although the elastic behaviour of artery was anisotropic unlike CPU, which was isotropic. Dacron and ePTFE grafts had lower complia nce values (1.8(1.2) and 1.2(0.3)per cent per mmHg x 10(-2) respectively, a veraged over the pressure range). In both these cases, compliance and stiff ness differed significantly from that of artery over a mean pressure range of 30-90 mmHg. Human saphenous vein exhibited anisotropic behaviour and, al though compliant at low pressure (30 mmHg), was markedly incompliant at hig her pressures. Conclusion: Compliant polyurethane grafts offer a greater degree of complia nce match than either ePTFE or Dacron.