Osamu Goto, MD, PhD
The concept of endoscopic submucosal dissection (ESD) emerged in late 1990s1 for the management of early gastric cancer. Since its introduction, this technique has continued to evolve with the ongoing development of dedicated electrosurgical devices and accessories. Currently, many knives have been developed and are commercially available worldwide. In general, these knives can be broadly divided into 3 categories: ceramic-tip insulated knives, needle-type knives, and scissors-type knives. The use of any particular type of knife or combination thereof is highly dependent on the operator’s preferences and lesion characteristics. In addition to electrocautery knives, various endoscopic accessories have been developed over the years aimed at improving the technical feasibility and safety profile of the procedure. This chapter briefly introduces the major electrosurgical knives and different accessories commonly utilized during ESD.
Insulated Endoscopic Submucosal Dissection Knives
Insulation-Tipped Diathermic Knife
Prior to ESD, a modified-endoscopic mucosal resection (circumferential mucosal incision followed by snaring resection) was introduced for the en bloc resection of superficial gastrointestinal (GI) neoplastic lesions. This technique was to some extent hampered by relatively high complication rates, particularly due to perforation, as the nondedicated electrosurgical devices available at that time were characterized by having long, noninsulated cutting blades. To reduce the risk of perforation during the procedure, Ono and colleagues developed a new type of knife with an insulated ceramic ball tip.1 This ceramic insulation-tipped knife, or ITKnife (Olympus), permits safe dissection with the long blade but reduces the risk of inadvertent tissue injury and perforation of the deeper layers from an unexposed tip. The introduction of the ITKnife has significantly reduced intraprocedural risks associated with endoscopic dissection, and helped propel ESD to become the endoscopic en bloc resection technique of choice for the treatment of superficial GI neoplasms, irrespective of size or submucosal fibrosis.1
The ITKnife permits fast submucosal dissection with its long blade, which translates into shorter operative times. However, its use can present challenges of its own as initial mucosal incision and subsequent dissection with the ITKnife requires precise contact and orientation between the blade and the cutting plane. To further improve the ease of use, particularly for beginners, a new ITKnife (ITKnife2, Olympus) was developed in 2006.2 In addition to an insulated ceramic tip, the ITKnife2 has a unique electrode design on the proximal side of the tip in the shape of 3 short blades. The innovative and uniquely triangular-shaped electrode further expanded the cutting versatility of the device by permitting dissection with not only the blade, but also by grasping the target tissue at various angles (Figure 11-1A). Currently, the ITKnife2 is commonly utilized in gastric ESD given its safety and shorter procedural time. Nonetheless, when compared to the original ITKnife, additional precaution should be taken to avoid injury to the deep muscle layer and even the potential for perforation from the electrode on the inside aspect of the distal ceramic tip.
A smaller version of the ITKnife2 (ITKnife-nano, Olympus) was introduced in 20123 for ESD in the esophagus and colon. The ITKnife-nano possesses a smaller insulation tip when compared to its predecessor and replaces the triangular-shaped electrode with a circular one. These changes enhance safety and increases knife maneuverability.
Uncovered Needle-Type Knives
The HookKnife (Olympus) is an orthogonally bended needle knife initially introduced by Oyama and Kikuchi.4 The right-angled tip of this needle knife allows dissection by hooking the target tissue. Furthermore, the direction of the tip can be rotated in the desired axis to allow safe and precise incision and/or dissection. The HookKnife is particularly useful for the dissection of lesions with severe fibrosis. Even in difficult situations where movement of an endoscope is restricted because of poor maneuverability, cutting can proceed by orienting the knife and dissecting by hooking and pulling on the knife itself.
A modified HookKnife with water-jet function (HookKnife J, Olympus) is also available in Asia. In addition to the L-shaped hook at the distal end, this ESD knife has a small orifice at the tip of the sheath that enables irrigation and submucosal injection (Figure 11-1B). The water-jet function on this ESD knife reduces the need for recurrent device exchange for the injection needle, which potentially reduces procedural time. Hence, the HookKnife J is the most commonly utilized hook-type needle knife where available.
In early 2000s, Yahagi et al introduced a short needle knife (FlexKnife, Olympus). The tip of this electrosurgical knife consisted of a loop cutting wire that could be adjusted to different lengths for marking, incision, and dissection. The DualKnife (Olympus)5 is a newer iteration of the original FlexKnife. This electrosurgical knife has a small, knob-shaped tip that enhances contact with tissue and provides stability, thereby reducing the risk of slippage during dissection. Furthermore, the knife length can be precisely adjusted to either a retracted or extended position, which makes it easier for the operator’s assistant when maneuvering the knife length. The extended knife protrudes either 2 mm or 1.5 mm for the stomach and other organs, respectively. Importantly, even in the retracted position, the cutting tip is exposed approximately 0.3 mm beyond the protective catheter. This is an ideal knife length for mucosal marking, hemostasis of small bleeding vessels, or during slow and steady dissection of fibrotic tissue. More recently, a modified DualKnife has been developed with the addition of a water-jet function, which allows irrigation and submucosal injection without exchanging the electrosurgical knife for an injection needle (DualKnife J, Olympus) (Figure 11-1C). Hence, the DualKnife J is a versatile electrosurgical knife as it can be used for marking, hemostasis, precutting, circumferential incision, submucosal injection and dissection.
The FlushKnife (Fujifilm) is a needle-type knife with a water-jet function that was first introduced by Toyonaga et al.6 The FlushKnife has a slim electrode tip that allows high voltage concentration. The FlushKnife BT (Fujifilm) has a 0.9 mm ball tip that enhances traction during dissection (Figure 11-1D). The FlushKnife and FlushKnife BT come with different protruding knife lengths, ranging from 1.0 to 3.0 mm and 1.5 to 3.0 mm, respectively. The FlushKnife BT is often preferred as the ball-tip design produces good traction for dissection and is effective for hemostasis.
The HybridKnife (Erbe)7 is another needle-type knife with high-pressured water-jet function. The high-pressure water jet emitted from this device penetrates the mucosa and effectively expands the submucosal space with fluid without the need of an actual needle. The HybridKnife comes with a straight tip (HybridKnife I-Type) or there is one with a disc-shaped plate (HybridKnife T-Type). The HybridKnife is preferred by many operators because it can be used in all stages of ESD, saving time by requiring fewer device exchanges.
The SB Knife (Sumitomo Bakelite) was the first scissors-type knife8 introduced in the market. The SB Knife, composed of 2 monopolar, smooth blades covered with an external electrically insulated coating, can be freely rotated 360 degrees. Opening and closing of the blades is controlled at the handle. The operator can visually confirm grasping of the target tissue prior to proceeding with cutting. Furthermore, prophylactic ablation of exposed vessels or hemostasis can be easily achieved with the soft coagulation mode. The scissor-type knife allows precise grasping and cutting of tissue with little endoscope position manipulation, which increases stability and safety. The SB Knife is available in different blade lengths, with the shorter blade varieties often used in other organs besides the stomach.
The Clutch Cutter (Fujifilm) is another type of rotatable scissor-type ESD knife with outer insulated blade edges.9 Unlike the SB Knife, the interior blades have serrated jaws, which potentially allow a firmer grip of the target tissue. The Clutch Cutter comes with 2 blade lengths (3.5 mm and 5.0 mm).
Endoscopic Submucosal Dissection Accessories
Intraoperative bleeding is an expected event during ESD. Prophylactic ablation of vessels and prompt hemostasis are key for a successful procedure. In most cases in which bleeding originates from small vessels, hemostasis can be adequately achieved with contact thermocoagulation by gently applying the tip of the electrosurgical knife to the bleeding point. However, profuse bleeding does occur from the large vessels penetrating the muscular layer. Adequate hemostasis is imperative to avoid brisk bleeding leading to poor endoscopic visualization, which can further hamper subsequent interventions.
Hot biopsy forceps are a readily available accessory that can be used for hemostasis during ESD. Because of its large serrated jaws, this device can be particularly helpful in the treatment of large penetrating vessels in the stomach but should be avoided in the colon given the higher risk for thermal injury of the thin colon wall and delayed perforation.