AN EXPERIMENTAL-MODEL OF SMALL-INTESTINAL SUBMUCOSA AS A GROWING VASCULAR GRAFT

Objective: The ideal vascular graft for use in children with congenita l heart disease should not only be biocompatible and nonthrombogenic a nd present no infectious risk, but ideally it should grow at the same rate as the recipient. Methods: We have tested autologous small intest ine submucosa as a superior vena cava interposition graft in 11 piglet s. The grafts were prepared from segments of jejunum, rendered nonthro mbogenic by heparin bonding. The superior vena cava from the level of the azygos vein to the superior vena cava-right atrial junction was re placed. Results: One early and 1 late death were not related to the gr aft material. At 90 days, the weight of the 9 survivors increased by 6 30%, from a mean of 10.3 +/- 2.0 kg to a mean of 59.2 +/- 16.7 kg (P < .001). The grafts increased in circumference by 184%, from a mean of 36.8 +/- 4.4 mm to a mean of 61.4 +/- 12.1 mm (P < .001) at late follo w-up. Their length increased by 147%, from a mean of 9.9 +/- 2.1 mm at implantation to a mean of 15.8 +/- 5.5 mm at explantation (P = .002), At the time of explantation, all 11 grafts were patent and free of th rombus, Cavograms showed no anastomotic stricture or aneurysm formatio n in 7 of 9 cases. The luminal surface of all grafts was smooth, shiny , and indistinguishable from that of the native cava, Light microscopy showed a loosely textured collagen framework, with a dense capillary network and complete luminal coverage by a single, continuous cell lay er displaying the ultrastructural features characteristic of endotheli al cells. Conclusion: Small intestine submucosa provides a collagen fr amework that becomes remodeled, grows, and acquires a nonthrombogenic endothelial lining. This makes it potentially well suited as a cardiov ascular substitute in children.