Evaluation of small intestine submucosa and acellular dermis as diaphragmatic prostheses

The repair of large congenital diaphragmatic defects in the neonate continues to be a challenge. Polytetrafluoroethylene (PTFE) is the synthetic material most widely used for reconstruction in instances of partial and complete diaphragmatic agenesis. Recurrent hernia is a frequent complication, because this material does not grow with the infant. This study evaluates two novel materials; small intestine submucosa (SIS; Cook Biotech, Lafayette, IN), and acellular dermis (AlloDerm; Lifecell Corp, The Woodland, TX) for diaphragm reconstruction in growing animals.

Sprague-Dawley rats (100 g, n = 87) were anesthetized and underwent laparotomy. The control group (n = 18) underwent a sham laparotomy with a left subcostal incision and closure. The other two groups underwent central excision of the left hemidiaphragm (50% loss) and reconstruction with either a SIS (n = 35) or AlloDerm (n = 19) patch sutured circumferentially with 6-0 prolene. Seventy-two animals survived the operation, and were killed at five separate time intervals (2 weeks, 1, 2, 3, and 4 months). Chest radiographs were performed monthly and before death. Radiographs were reviewed in a blinded fashion by two observers as were the necropsies, and rib deformity was noted if present. Histological examination of the diaphragm patch was performed in each animal.

There was no evidence of rib deformity noted on gross examination at necropsy or on chest radiograph in either experimental group. At necropsy, all patches were intact without hernia, eventration, or contraction. Histology findings initially showed acute and chronic inflammatory changes in both patch materials that lessened at the 2-month time interval. Both prosthetic patches began to thin at 3 months and was most prominent in the SIS rats. At 4 months, both SIS and AlloDerm remained viable without evidence of necrosis. Each patch showed evidence of fibroblastic incorporation and small capillary ingrowth. These changes were more prominent in the AlloDerm group. There was no evidence of skeletal muscle ingrowth.

These data indicate SIS and AlloDerm may be useful materials for prosthetic repair in instances of partial or total agenesis of the diaphragm. Further investigation in a large animal model over a longer duration is indicated.