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DualKnife

Model KD-650L

Dr. Naohisa Yahagi
Keio Universitiy

Interview With The Expert

What are the advantages of DualKnife?
DualKnife is an improvement over FlexKnife that offers safer and easier use while it continuously provides all the benefits of FlexKnife.

DualKnife can be set to either of two lengths. When the knife is extended to maximum length, it can be used for incision and dissection. When the knife is retracted, the knife tip still protrudes by 0.3 mm so it can be used for marking as well as simple haemostasis. The knife length can be set to either 2 mm or 1.5 mm.
The 2 mm length is for gastric ESD, while the 1.5 mm length is for oesophageal ESD. The knife tip has a projecting section, which catches the tissue during incision and dissection, considerably improving knife manoeuvrability.
Moreover, the dome-shaped knife tip improves the knife contact during incision and dissection. In addition, the outer diameter of the sheath is just 2 mm, so smooth water and smoke suction is possible even when the knife is retracted in the instrument channel.

What are the differences between FlexKnife and DualKnife in terms of operation and precautions?
The basic procedures are identical,

but the thin, needle-shaped design of DualKnife provides superior incision performance. Consequently, physicians typically set DualKnife’s high-frequency power about 10 W lower than FlexKnife. In addition, burnt tissue does not get attached to DualKnife compared to FlexKnife. Even when residue is adhered to the tip, it can be removed by moving the knife back and forth a few times and allows continuous use.
While FlexKnife needs fine adjustment for knife length, DualKnife can accurately set the knife length into two lengths. This also makes it easier for the operation assistant to handle.

Are there any weak points of DualKnife?
The knife is short so it cannot incise unless the knife is brought in contact optimally.

The thinness of the sheath could make it more difficult to transmit force to the tip when the sheath is extended. It is more effective to use the multi-bending endoscope when treating a lesion in a hard-to-approach region.

Under what circumstances would you also use another device?
Though not as frequently as when I used FlexKnife,

I sometimes switch to HookKnife when I encounter advanced fibrosis during dissection, limited space for endoscope manoeuvre, or unstable knife contact due to severe respiratory movements. Haemostasis for small amount of bleeding can generally be achieved by bringing the retracted knife in contact for coagulation. For pulsatile bleeding, I use Coagrasper.

Applicability of DualKnife

Difficulty per region

◯ : Easy.  No mark: Ordinary.  △ : Difficult.

Cardiac region  △  
 Fornix  △  
 Lesser curvature of upper body    
 Greater curvature of upper body  △  Bleeding makes a pool of blood.
 Anterior wall of upper body  △  
 Posterior wall of upper body  △  Tends to bleed heavily.
 Lesser curvature of middle body  ◯  
Greater curvature of middle body  △  Bleeding makes a pool of blood.
 Anterior wall of middle body  △  
 Posterior wall of middle body    
 Lesser curvature of lower body    When gastric angulus widens, distance is made between the device and mucosa and it is difficult to transmit proper force.
Multi-bending endoscope enables easy operation.
 Greater curvature of lower body    
 Anterior wall of lower body    
 Posterior wall of lower body    
 Lesser curvature of anterior wall  
 Greater curvature of antrum  
 Anterior wall of antrum  
 Posterior wall of antrum  
 Pyloric ring  
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