Establishing a swine model to compare vascular prostheses in a contaminated field

Patch arteriotomies are performed during many vascular procedures. Whereas synthetic materials are generally felt to be inappropriate for infected environments, the suitability of glutaraldehyde-treated bovine pericardium (GBP), a biologic material, in such instances is unknown. Our main objectives were to develop an animal model to study vascular prostheses while comparing the infectability of polyester (Dacron) and GBP in a topically infected environment.

Twenty-three pigs underwent transabdominal patch arteriotomy of the infrarenal aorta with either Dacron or GBP. The patches were inoculated with sterile saline (1 per group), Staphylococcus aureus 10(4) colony-forming units (CFUs) (4 per group), or S. aureus 10(5) CFUs (6 per group). At 3 wk, the animals were euthanized, and the patches were removed via a left retroperitoneal approach. Specimens were collected for microbiologic and histologic analysis.

One animal from each group inoculated with 10(5) CFUs died during the study period, and another died immediately postoperatively of an airway complication. All aortas were patent and without evidence of pseudoaneurysm formation. Gross abscesses were found in 4/6 Dacron and 5/6 GBP animals receiving 10(5) CFUs. Similarly, 4/6 animals implanted with Dacron and 5/6 animals implanted with GBP had positive tissue cultures. A histologic grading system of inflammation substantiated the culture results.

No significant difference exists between Dacron and GBP to resist bacterial infection at 3 wk. We have established a reproducible in vivo model to study arterial patch materials in a topically infected environment.