Transmural gastric closure and NOTES – How far have we come?

The ability to perform secure closure of transmural gastric defects will represent a significant milestone in the evolution of therapeutic gastrointestinal endoscopy. In 1958, the flexible fiberoptic endoscope was introduced by Larry Curtiss and Basil Hirschowitz as a diagnostic modality. Over the ensuing decades, an interventional focus gradually took shape – initially for more invasive diagnostic techniques, such as biopsies and polypectomies, but later encompassing hemostasis, pancreaticobiliary procedures (i. e., endoscopic retrograde cholangiopancreatography and sphincterotomies), fine needle aspirations under endoscopic ultrasound guidance, and endoscopic mucosal resection and endoscopic submucosal dissection for resection of early-stage cancers. However, this growing interventional focus was mostly confined to the gastrointestinal lumen.

The arrival of natural-orifice transluminal endoscopic surgery (NOTES) in 2005 allowed therapeutic endoscopy to move beyond the gastrointestinal lumen. Breaching the gut wall – once anathema to the endoscopist and a reflexive, urgent call to the surgeon – now opened doors to intraperitoneal endoscopic procedures. It became conceivable that endoscopists could be outside the gastrointestinal tract, performing such tasks as directed liver biopsies or sampling lymph nodes. Some of the more adventurous among the therapeutic community even attempted organ resection or prosthetic implantation. However, regardless of one’s particular vision of NOTES, it was ultimately predicated on the existence of a reproducible and 100 % safe means of closing the perforation.

NOTES has been about pushing boundaries. As NOTES pushes the extraluminal boundary, it pushes the endoluminal boundary as well. Technological solutions directed towards secure NOTES closure carry significant “spin-off” potential for the advancement of endoluminal therapy. For example, full-thickness resection becomes conceptually feasible. Bariatric patients with gastrogastric fistulae may have an endoscopic means of fistula closure. Gastroenterologists performing endoscopic mucosal resection or more aggressive endoscopic submucosal dissection need not dread inadvertent perforation if a means of adequate closure exists.

Where does transmural gastric closure currently stand? From a technical perspective, various types of closure modalities abound. Clips, suture, T-tags, staples, tissue anchors, pledgets, ligatures, occluding devices, and percutaneous endoscopic gastrostomy tubes have all been used. Many of these techniques or devices appear to produce reproducible closures, some even yielding leak pressures comparable or superior to those of hand-sewn controls. Some have also been demonstrated successfully in the animal survival model.

In this issue of Endoscopy, Hookey et al. present a survival study based on an innovative technique using endoscopic clips and endoloops. While this technique carries the advantage of employing commonly available endoscopic accessories, it is somewhat time-consuming, as demonstrated by the mean time of external loop placement (14 minutes) combined with the mean time of completion of closure (38 minutes) after peritoneoscopy. In contrast, Trunzo et al. present an application of the TAS device, a technology based on T-tags, for gastric closure. Like the clip-and-loop technique, the TAS technique requires prefixation of T-tags prior to gastrotomy creation. However, as pointed out by the authors, there is a real concern about inadvertent penetration of abdominal viscera because of the blind nature of T-tag deployment. Furthermore, the significance of the low burst pressures presented in this acute porcine study remains to be evaluated in survival studies. Finally, von Renteln et al. report their experience with the OTSC device for closure of colonic perforations, which may also translate to closures of full-thickness gastric defects. The appeal of the OTSC lies in its relative automation and efficiency. However, questions remain regarding this device. Due to the size and mechanism of action of the device, its application will likely be limited to smaller gastric defects. Additionally, issues of device retention and passage have not yet been fully clarified.

Although there are an abundance of closure modalities, and studies thereof, there is still a shortage of human safety data. While there have been several recent publications on hybrid endoscopic–laparoscopic gastric surgeries, the majority of gastric closures in these surgeries were performed laparoscopically. There is one published human case series evaluating gastric closure using endoscopic staplers [1]. Additionally, there has been an oral presentation of a human transgastric cholecystectomy case series where the USGI tissue-anchor device was used for gastrotomy closure [2]. Nevertheless, there is currently little human data to support clinical use.

In evaluating the current status of gastric closure, there is also a relevant marketing/commercial aspect to consider. As Dr. Fritscher-Ravens has pointed out in a recent editorial [3], while several promising prototypes exist, none has made it to market beyond preclinical and clinical studies. One possible reason for this is that a NOTES closure device is considered a “boutique device” for a limited market. High research and development costs in conjunction with a limited production line may make commercialization of a NOTES closure device prohibitively expensive.

The future success of gastric closure devices may lie in their ability to simultaneously address both the NOTES and the endoluminal markets. There are several potential variations on this theme. For example, a suturing device may be primarily developed for a comparatively larger endoluminal market, such as endoluminal bariatrics or endoluminal gastroesophageal reflux disease, and see a second life with NOTES gastric closure. Alternatively, a closure device may be simultaneously developed for gastric closure of all types – whether they are for purposeful incisions and full-thickness resections, or for iatrogenic perforations. In this latter scenario, however, it is important to point out that many of the current closure devices are designed for controlled situations – i. e., the closure modality is deployed prior to the incision. In iatrogenic perforations, the closure modality would not be predeployed. The endoscopist would likely be dealing with lack of insufflation and free tissue flaps to be apposed, representing an entirely different and more complicated closure scenario.

Generally speaking, the advancement of NOTES is heavily dependent on device development. It traditionally takes about 5 – 10 years for new devices to gain traction in gastrointestinal endoscopy. As such, we are about to enter a potentially fruitful time period for full-thickness gastric closure devices. If a reliable closure device can come to market in the near future, this would represent not only a critical milestone for NOTES but for endoluminal therapy as well. In the end, gastrointestinal endoscopy has nearly always succeeded wherever it has ventured, and there is no reason to think that it will not succeed in the arena of gastric closure.

References

• 1 Kaehler G, Grobholz R, Langner C. et al . A new technique of endoscopic full-thickness resection using a flexible stapler.  Endoscopy. 2006;  38 86-89
• 2 Ujiki M B. Biliary – Human NOTES transgastric cholecystectomy. The DAVE Project. Retrieved 5 May 2009, from http://daveproject.org/viewfilms.cfm?film_id = 758 . 
• 3 Fritscher-Ravens A. A market for gastric NOTES closure: which path should we follow?.  Endoscopy. 2009;  41 160-161