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

Abstract

Small-intestine submucosa (SIS) is cell-free collagen, 100 mu 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 reporting 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 = E(o)e(alphaP), where Eo is the zero-pressure modulus and alpha 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 alpha was 0.0059 (range 0.0028-0.0125). At 100 mmHg, the mean value for E was 8.91 x 10(3) g/cm2 (range 1.02-8.80 x 10(3)). 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 (1/2) 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.

Rolling the Human Amnion to Engineer Laminated Vascular Tissues

“…The engineering stress values for ringlets was calculated using r ¼ F (2tw) where 2tw is the cross-sectional area of the ringlet. The elastic modulus (EM) corresponds to the stress/ strain (s/3), 26 which is defined as force/unit area. EM was assessed from 0.01 MPa (80 mmHg) to a maximum of 0.02 MPa (120 mmHg) corresponding to a low-strain region that reflects physiologic behavior (physiologic range).…”

“…Color images available online at www.liebertpub.com/tec %/mmHg as d/(EM2t). 26 The rupture strength corresponds to the maximum stress at sample rupture.…”

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Tissue Engineering for Tissue and Organ Regeneration

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