Transgastric biologic mesh delivery and abdominal wall hernia repair in a porcine model

Assessment of Human Acellular Dermis Graft in Porcine Models for Ventral Hernia Repair

OBJECTIVE

Preclinical evaluation of hernia meshes is commonly performed in porcine models. We recently developed two surgically induced porcine hernia models-an incisional and an excisional model-that formed persistent hernias in the absence of graft repair. Herein, we investigate if these models will continue to form a hernia after graft repair.

MATERIALS AND METHODS

Ten pigs were used to create two hernia models-a 10-cm partial-thickness incisional defect (n = 5) and an 8 × 8-cm full-thickness excisional defect (n = 5). The defects were repaired using a 12 × 12-cm human acellular dermis graft placed in a preperitoneal/retrorectus sublay position and fixed using transfascial sutures. Postoperative management included the use of suction drainage for 1 week and an abdominal binder for 4 weeks in the more severe excisional model. Hernia development was assessed clinically, and hernia defect size and volume were measured using postoperative computed tomography (CT) imaging over 12 weeks. Radiographic inflation testing (2 L inflation), biaxial mechanical testing, and histological evaluation were also performed at 12 weeks.

RESULTS

All pigs with the excisional model, but none with the incisional model, developed a clinically relevant hernia. At the end of 12 weeks, the excisional model had a significantly greater hernia defect size (259 ± 51 cm² vs. 47 ± 16 cm²) and repair volume (865 ± 414 cm³ vs. 85 ± 52 cm³) compared with the incisional model. The excisional model also showed an order of magnitude greater increase in repair volume (280 cm³ vs. 47 cm³) compared with the incisional model upon 2 L inflation. Furthermore, the excisional model showed a trend of having higher dilatational strain at average biaxial load of 250 N and lower stiffness compared with the incisional model. The excisional model had a thin, hypercellular hernia sac spanning the defect, whereas the incisional model had a thick densely fibrotic scar bridging the defect.

CONCLUSION

The 8 × 8-cm excisional defect model, together with appropriate postoperative wound management, in the pig model is recommended for preclinical investigation of different grafts for hernia repair. Novel CT imaging and biomechanical testing methods are recommended to measure functional outcomes of hernia repair in preclinical models.

Natural-orifice transluminal endoscopic surgery

BACKGROUND

Natural-orifice transluminal endoscopic surgery (NOTES) represents one of the most significant innovations in surgery to emerge since the advent of laparoscopy. A decade of progress with this approach has now been catalogued, and yet its clinical application remains controversial.

METHODS

A PubMed search was carried out for articles describing NOTES in both the preclinical and the clinical setting. Public perceptions and expert opinion regarding NOTES in the published literature were analysed carefully.

RESULTS

Two hundred relevant articles on NOTES were studied and the outcomes reviewed. A division between direct- and indirect-target NOTES was established. The areas with the most promising clinical application included direct-target NOTES, such as transanal total mesorectal excision and peroral endoscopic myotomy. The clinical experience with distant-target NOTES, such as for appendicectomy and cholecystectomy, showed feasibility; however, NOTES-specific morbidity was introduced and this represents an important limitation.

CONCLUSION

NOTES experimentation in the preclinical setting has increased substantially. There has also been a significant increase in the application of NOTES in humans in the past decade. Enthusiasm for NOTES should be tempered by the risk of incurring NOTES-specific morbidity. Surgeons should carefully consider patient preferences regarding this new minimally invasive option, as opinions are not unanimously supportive of NOTES. As technical limitations are overcome, the clinical application of NOTES is predicted to increase. It is paramount that, when this complex technique is performed on humans, it is applied judiciously by appropriately trained experts with outcomes recorded in a registry.

Feasibility of transumbilical flexible endoscopic preperitoneoscopy (FLEPP) and its utility for inguinal hernia repair: experimental animal study

BACKGROUND AND STUDY AIMS

Various NOTES (natural orifice translumenal endoscopic surgery) hernia repair techniques have been described. The aim of this study was to evaluate the feasibility of a transumibilically introduced conventional double-channel flexible endoscope for performing preperitoneoscopy (FLEPP, flexible endoscopic preperitoneoscopy technique) and to perform totally extraperitoneal (TEP) inguinal hernia meshplasty in an animal model.

MATERIAL AND METHODS

The study was done in 2 steps on 8 swines weighing 25 to 30 kg each: (1) establishing feasibility of preperitoneal dissection of the inguinal region using a conventional double-channel flexible gastroscope and making bed for mesh placement and (2) placement of a polypropylene mesh in the inguinal region to cover the myopectineal orifice.

RESULTS

The flexible endoscope provided good vision and maneuverability to identify preperitoneal structures--namely, the arcuate line, insertion of rectus abdominis on pubis symphysis, inferior epigastric vessels, deep inguinal ring, spermatic cord, pubic symphysis, and psoas muscle--without causing any damage to any of the structures. The spermatic cord could be dissected to identify the vas deference. A 9 × 7 cm(2) oval mesh was successfully placed over the myopectineal orifice of Fruchaud with good overlap. Average time required for the complete FLEPP procedure (including mesh placement) was 55 minutes (range 45-90 minutes).

CONCLUSIONS

This study demonstrates, for the first time, the feasibility of the transumbilical FLEPP technique and its utility for performing TEP inguinal hernia repair with prosthetic mesh placement in a swine model.

Prosthetic mesh contamination during NOTES(®) transgastric hernia repair: a randomized controlled trial with swine explants

PURPOSE

Natural Orifice Translumenal Endoscopic Surgery (NOTES(®)) is a developing field in minimally invasive surgery that has been applied across a wide range of procedures; however, infectious concerns remain. Most of the applications have been for extraction, rather than reconstructive procedures. Prosthetic hernia repair, is a constructive procedure, has the unique challenge of avoiding contamination and infection of a permanent implant. Utilizing a novel device, we hypothesize that we can significantly reduce or eliminate prosthetic contamination during a transgastric approach for delivery of a clinically relevant, permanent, synthetic prosthetic.

METHODS

20 swine explants of stomach with attached esophagus were prepared by placing an ultraviolet (UV) light sensitive gel within the lumen of the stomach. Each stomach then underwent endoscopic gastrotomy utilizing a needle, wire guide, and 18-mm balloon dilator. A 10 × 15 cm polypropylene prosthetic was rolled and tied with a 2-0 silk suture, and delivered with one of two methods. Group A (control) utilized a snare to grasp the prosthetic adjacent to the endoscope, which was used to drag it through the gastrotomy. Group B (device) utilized a modified esophageal stent delivery system to deliver the prosthetic through the gastrotomy. Each prosthetic was then digitally photographed with UV illumination, with the contaminated areas illuminating brightly. Software analysis was performed on the photographs to quantify areas of contamination for each group. Statistical analysis was performed using a two-tailed t test with unequal variance.

RESULTS

Group A demonstrated a mean of 57 % of the surface area of the prosthetic contaminated with UV light sensitive gel. Group B (experimental group) showed a mean of 0.01 % of the surface area contaminated (p < 0.0001). 95 % confidence intervals indicated that the unprotected delivery technique exposes approximately 6,000 times more of the surface area to contamination than the delivery device.

CONCLUSION

Use of this modified stent delivery system can nearly eliminate prosthetic contamination when placed via a transgastric approach in a swine explants model. Theoretically, the reduced inoculum size would reduce or eliminate clinical infection. Since the inoculum size required for clinical prosthetic infection for intraperitoneal mesh is unknown, further study is warranted to test the ability to eliminate clinical infection related to prosthetic delivery with this technique.

Critical analysis of hot topics in NOTES

Natural orifice transluminal endoscopic surgery (NOTES) has gained a great deal of attention from gastroenterologists and surgeons all over the world since its introduction in 2000. The field of NOTES has advanced tremendously since that time and exciting and well-designed research has been reported. Both randomized controlled trials and results from large national and international registries have been published. Many experimental and clinical studies have discussed transesophageal, transgastric, transvaginal and transrectal access for a variety of NOTES procedures. Transvaginal access has been the most frequently reported NOTES access route in clinical trials. When suitable instruments become available, a true comparison of NOTES with current laparoscopic approaches can be realized.

Natural orifice translumenal endoscopic surgery

PURPOSE OF REVIEW

Since its introduction in 2000, natural orifice translumenal endoscopic surgery (NOTES) has gained a great deal of attention from gastroenterologists and surgeons all over the world. In this article, we will review the progress in the field of NOTES and present the latest publications that provide some answers and solutions to the barriers suggested by the Natural Orifice Surgery Consortium for Assessment and Research white paper.

RECENT FINDINGS

Because of the first human NOTES procedure by Rao and Reddy, more pioneering procedures, including transgastric and transvaginal cholecystectomies, appendectomies, and hernia repairs, have been performed. Although NOTES researchers continue to experiment with new innovative equipment and procedures in the lab, more structured work, including randomized controlled trials, has been published.

SUMMARY

In the last several years, there has been growing interest in NOTES, which has translated into exciting animal research work and publication of randomized controlled trials. Additionally, preliminary NOTES human procedures have been successfully performed. When suitable instruments become available, the subsequent step should be comparing NOTES with current laparoscopic approaches. Superiority or even equality of NOTES to laparoscopic surgery would be the best argument for advancing and integrating implementation into clinical practice.