Compliance, elastic modulus, and burst pressure of small-intestine submucosa (SIS), small-diameter vascular grafts

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Abstract
Small-intestine submucosa (SIS) is cell-free collagen, 100 μ thick, derived from the small intestine. It has been used as a vascular graft and has the highly desirable property of remodeling itself to become host tissue. To date there has been limited reportage on its preimplantation mechanical properties as a vascular graft. In this study, compliance, elastic modulus, and burst pressure have been measured on 5- and 8-mm SIS grafts. The compliance (percent of diameter increase for a pressure rise from 80 to 120 mmHg) was 4.6% av (range 2.9 to 8.6%) for the 5-mm grafts. For the 8-mm graft, the increase in diameter for the same pressure rise was 8.7% av (range 7.2 to 9.5%). The modulus of elasticity (E) increased exponentially with increasing pressure according to E = EoeαP, where Eo is the zero-pressure modulus and α is the exponent that describes the rate of increase in E with pressure; the units for E, Eo, and P are g/cm2. The mean value for Eo was 4106 (g/cm2 range 1348–5601). The mean value for α was 0.0059 (range 0.0028–0.0125). At 100 mmHg, the mean value for E was 8.91 × 103 g/cm2 (range 1.02–8.80 × 103). The mean burst pressure for 5.5-mm grafts was 3517 mm Hg (range 2069–4654). In terms of preimplant compliance, the small-diameter SIS graft is about ½ as compliant as the dog carotid artery, about four times more compliant than a typical vein graft, and more than an order of magnitude more compliant than synthetic vascular grafts. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res, 47, 65–70, 1999.