Relationship between tissue ingrowth and mesh contraction.

Contraction is a well-documented phenomenon occurring within two months of mesh implantation. Its etiology is unknown, but it is suggested to occur as a result of inadequate tissue ingrowth into the mesh and has been associated with hernia recurrence. In continuation of our previous studies, we compared tissue ingrowth characteristics of large patches of polyester (PE) and heavyweight polypropylene (PP) and their effect on mesh contraction. The materials used were eight PE and eight PP meshes measuring 10 x 10 cm2. After random assignment to the implantation sites, the meshes were fixed to the abdominal wall fascia of swine using interrupted polypropylene sutures. A necropsy was performed three months after surgery for evaluation of mesh contraction/shrinkage. Using a tensiometer, tissue ingrowth was assessed by measuring the force necessary to detach the mesh from the fascia. Histologic analysis included inflammatory and fibroblastic reactions, scored on a 0-4 point scale. One swine developed a severe wound infection that involved two PP meshes and was therefore excluded from the study. The mean area covered by the PE meshes (87 +/- 7 cm2) was significantly larger than the area covered by the PP meshes (67 +/- 14 cm2) (p = 0.006). Tissue ingrowth force of the PE meshes (194 +/- 37 N) had a trend toward being higher than that of the PP meshes (159 +/- 43 N), although it did not reach statistical significance. There was no difference in histologic inflammatory and fibroblastic reactions between mesh types. There was a significant correlation between tissue ingrowth force and mesh size (p = 0.03, 95% CI: 0.05-0.84). Our results confirm those from previous studies in that mesh materials undergo significant contraction after suture fixation to the fascia. PE resulted in less contraction than polypropylene. A strong integration of the mesh into the tissue helps prevent this phenomenon, which is evidenced by a significant correlation between tissue ingrowth force and mesh size.

The effects of gastric surgery on systemic ghrelin levels in the morbidly obese.

HYPOTHESIS: Circulating ghrelin, produced primarily in the stomach, is a powerful orexigen. Ghrelin levels are elevated in states of hunger, but rapidly decline postprandially. Early alterations in ghrelin levels in morbidly obese patients undergoing weight reduction surgery may be attributed to gastric partitioning. DESIGN AND PATIENTS: Thirty-four patients underwent Roux-en-Y gastric bypass with a completely divided gastroplasty to create a 15-mL vertically oriented gastric pouch. Eight other patients underwent other gastric procedures that did not involve complete division of the stomach, including 4 vertical banded gastroplasties and 4 antireflux surgical procedures. Six additional patients undergoing antireflux surgery served as lean control subjects. Plasma samples were obtained before surgery and immediately after surgery. In a substudy, plasma was collected after Roux-en-Y limb formation and after dividing the stomach to identify any changes in plasma ghrelin levels. SETTING: Tertiary university medical center. MAIN OUTCOME MEASURES: Ghrelin levels at different stages of surgical intervention. RESULTS: Mean +/- SEM preoperative and postoperative ghrelin levels in the gastric bypass group were 355 +/- 20 and 246 +/- 13 pg/mL, respectively (P<.001). In the vertical banded gastroplasty group and in all patients undergoing antireflux surgery, ghrelin levels were not significantly changed. CONCLUSIONS: Compared with morbidly obese humans, lean controls had significantly higher plasma ghrelin levels at baseline. A divided gastroplasty creating a small proximal gastric pouch results in significant early declines in circulating ghrelin levels that are not observed with other gastric procedures. This may explain, in part, the loss of hunger sensation and rapid weight loss observed following gastric bypass surgery.