Endoscopic Suturing, an Essential Enabling Technology for New NOTES Interventions

Natural orifice transluminal endoscopic surgery (NOTES) was developed as a new, minimally invasive approach for various interventions inside the peritoneal cavity. Since the first reports of NOTES animal interventions, various devices have been used for closure of the transluminal entrance site. This article reviews the most commonly used endoscopic closure devices and advantages of the latest generation of endoscopic suturing devices enabling reliable, surgical-quality closure of the full-thickness gastrointestinal wall defects.

Key points

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Reliable closure of the transluminal entrance site is paramount to prevent postoperative leakages and infectious complications.
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The Overstitch (Apollo Endosurgery Inc, Austin, TX) endoscopic suturing device creates a reliable, full-thickness, surgical-quality, airtight closure of transmural gastrointestinal tract defects.
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Endoscopic suturing is an essential enabling technology for new natural orifice transluminal endoscopic surgery interventions.

Peroral transluminal endoscopic surgery was started with a series of animal experiments, which demonstrated the ability to enter the peritoneal cavity through the gastric wall without any damage to organs surrounding the stomach. During the first reported transluminal interventions in animal models, a full-thickness gastric wall incision was made, a flexible endoscope was introduced into the peritoneal cavity to perform liver biopsy, and then the endoscope was withdrawn back to the stomach and the gastric wall defect was completely closed with endoscopic clips. After this report of feasibility of transluminal endoscopic intraperitoneal interventions, numerous abstracts and full-length articles have described in acute and survival animal studies transgastric peritoneoscopy, gastro-jejunostomy, tubal ligation, cholecystectomy, splenectomy, and other intraperitoneal interventions on live animal models. In 2006, the Natural Orifice Consortium for Assessment and Research was formed and the term natural orifice transluminal endoscopic surgery (NOTES) was invented.

Since that time numerous NOTES procedures in humans were performed, including transgastric peritoneoscopy and liver biopsy, transgastric and transvaginal cholecystectomies and appendectomies, NOTES percutaneous endoscopic gastrostomy rescue procedures, and other interventions.

However, peroral and transvaginal interventions on intraperitoneal organs have not demonstrated convincing advantages over traditional laparoscopic surgery.

The authors think that the real potential of NOTES has not yet been explored. The unique advantages of a NOTES approach over traditional and laparoscopic surgery are in procedures such as purely endoscopic full-thickness resection of gastrointestinal (GI) tract lesions. These new NOTES procedures are not possible without reliable, surgical-quality closure of transmural GI tract wall defects.

Table 1 summarizes accessories and endoscopic suturing devices previously used for closure of NOTES entrance sites into the peritoneal cavity.

Table 1

Accessories and devices for closure of the NOTES incision

Type	Name	Manufacturer	Available for Clinical Use
Through-the-scope endoscopic clips	QuickClip2 and QuickClip Pro	Olympus Optical Ltd, Tokyo, Japan	Yes
	Resolution	Boston Scientific, Natick, MA	Yes
	Instinct	Cook Medical, Bloomington, IN	Yes
Over-the-scope clip	Over-The-Scope Clip (OTSC) System	Ovesco , Tübingen, Germany	Yes
Over-the-scope clip	Padlock Clip	Aponos, Kingston, NH	Yes
Suction based	EndoCinch	Bard, Murray Hill, NJ	Yes
	LSI Solution	Victor, NY	No
	Spiderman	Ethicon Endo Surgery, Cincinnati, OH	No
Working overtube delivering preloaded stitch	NDO plicator	NDO Surgical, Mansfield, MA	No
T-bars deployment with subsequent cinching	TAS system	Ethicon Endo Surgery, Cincinnati, OH	No
	T-bars	Cook Endoscopy, Winston-Salem, NC	No
	T-bars	Olympus Optical LTD, Tokyo, Japan	No
Flexible stapler	PowerMedical	Acquired by Medtronic, Minneapolis, MN	No
Use of curved needle	G-Prox	USGI Medical, San Clemente, CA	Yes
	Eagle Claw	Olympus Optical LTD, Tokyo, Japan	No
	Overstitch	Apollo Endosurgery Inc, Austin, TX	Yes

Through-the-scope endoscopic clips are commercially available devices, which were widely used during initial NOTES animal experiments. Unfortunately, these clips were created for endoscopic hemostasis and not for tissue approximation. Through-the scope clips only provided mucosa-to-mucosa apposition. Endoscopic hemostatic clips could not achieve reliable closure of NOTES incisions and were far inferior to surgical suturing closure as demonstrated in animal experiments comparing burst pressures between various types of endoscopic closure techniques.

Compared with the small through-the-scope clips, the over-the-scope clips (OTSC [Ovesco Endoscopy, Tübingen, Germany], Padlock Clip [Aponos, Kingston, NH]) are very robust devices allowing even a full-thickness closure of GI tract defects. Over-the-scope clips are preloaded on the distal end of the flexible endoscope for delivery to the site of their application. However, the size of defect amenable to closure with these devices is limited by the space inside the over-the-scope clip; in case of suboptimal placement, these clips are very difficult to remove and cannot be repositioned after initial deployment.

The first endoscopic suturing devices, which were used in animal experiments for closure of NOTES entrances into the peritoneal cavity (EndoCinch [Bard, Murray Hill, NJ], LSI Solution [Victor, NY], Spiderman [Ethicon Endo Surgery, Cincinnati, OH]), were based on suctioning of tissue into a suction chamber mounted on the distal tip of the flexible endoscope. Then a needle with suture was passed through the suctioned tissue to deliver a stitch. After advancement of the needle through both edges of the NOTES incision, the suture was finished with extracorporeal knot tying or intracorporeal cinching. Unfortunately, use of suction could not provide predictable and adequate depth of the suture delivery and most sutures were too superficial, located only in the mucosal and submucosal layers.

NDO plicator (NDO Surgical, Mansfield, MA) used a specially created overtube with preloaded stitches. Although this device was created specifically for correction of gastroesophageal reflux disease, it was successfully used for endoscopic full-thickness suturing and potentially could be used for closure of NOTES entrance into peritoneal cavity. However, this device could only deliver a single stitch of predetermined length and after each application needed removal from patients for reloading. Manufacturing of this suturing device was discontinued, and it is no longer commercially available for clinical use in humans.

Several companies (Ethicon Endo Surgery, Cincinnati, OH; Cook Endoscopy, Winston-Salem, NC; Olympus Optical LTD, Tokyo, Japan) developed suturing devices based on hollow needles delivering T-bars. Unfortunately, T-bars were delivered into the edges of the NOTES incision through a blind puncture of the GI tract wall, which could potentially cause damage to adjacent intraperitoneal organs and blood vessels. None of these devices is currently commercially available for clinical use in humans.

A flexible endoscopic stapler was originally developed by PowerMedical and later acquired by Medtronic (Minneapolis, MN). Numerous acute and survival animal experiments demonstrated effectiveness of this device for closure of full-thickness defects in the GI tract wall. However, this device was very difficult to navigate and required removal from patients for reloading. It is no longer available for clinical use.

Endoscopic suturing devices using a curved needle (G-Prox [USGI Medical, San Clemente, CA], Eagle Claw [Olympus Optical LTD, Tokyo, Japan], and Overstitch [Apollo Endosurgery Inc, Austin, TX]) most closely resemble surgical suturing. The G-Prox tissue approximation system uses a curved needle to deliver specially designed suture material with baskets on both ends. The outer diameter of the G-Prox device is bigger than the biopsy channel of existing flexible endoscopes and requires the use of the special TransPort system (USGI Medical, San Clemente, CA).

Eagle Claw was specifically created for endoscopic suturing including closure of NOTES entrance into the peritoneal cavity, creation of anastomosis, and other interventions inside the peritoneal cavity and GI tract. However, Eagle Claw could only create separate stitches of limited length and required removal from patients after completion of each stitch for reloading. Although several consecutive prototypes of Eagle Claw have been made, it is still not available for human use.

The only commercially available endoscopic suturing device now (currently available in Europe and the United States) is Overstitch made by Apollo Endosurgery Inc, (Austin, TX). The current version of Overstitch is front-loaded on a double-channel endoscope (GiF-2T160 or GiF-2T180, Olympus Optical Ltd, Tokyo, Japan) fitted inside the endoscope’s larger channel with a special spring-loaded mechanism and actuated by a handle that clips onto the endoscope ( Fig. 1 ).