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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_605_Библиотеки_им_академика_М_И_Перельмана.pdf
Interventional Flexible Endoscopy
Figure 8.6 Hook knife: Top: Retracted; below: working position of the tip. Monopolar
diathermy provides cutting and/or coagulation. From MITI.
Figure 8.7 (A) Oval snare; (B) crescent-shaped snare; (C) hexagonal snare. All from
MITI.
333
Detachable snares or loops which can be left in place are useful
because of the tourniquet effect: They can be, e.g., placed at the base of a
pedunculated polyp to occlude blood supply. The polyp can, then, be
safely transected by means of another (electrocautery) snare.
Recently, an interesting new application of the detachable snare was
published for mucosal closure. The detachable clip is deployed around the
mucosal defect and fixated by means of clips to the edges. Closure of the
snare occludes the defect (
Fig. 8.8).
8.2.4 Injection Needles
Injection needle instruments are inserted into the working channel with
the tip of the needle retracted into the internal lumen. Prior to injection,
the sharp tip is moved forward to pierce the tissue. Hemostatic agents are
injected to stop bleedings (
Fig. 8.9).
Fluid is delivered into the submucosal layer of the gastrointestinal (GI)
wall to produce a cushion beneath the mucosa which facilitates excision.
8.2.5 Forceps/Graspers
Endoscopic forceps are predominantly used to take biopsies, i.e., for tissue
sampling. They usually consist of a pair of sharpened cups, the flexible
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Biomedical Engineering in Gastrointestinal Surgery
Figure 8.8 (A) Mucosal closure with a detachable snare and clips after endoscopic
submucosal dissection. (a) A mucosal defect remains after ESD. (b) A detachable
snare is deployed on the mucosal defect through a working channel, and a rotating
clip-fixing device with a long clip is inserted through the other working channel.
(c) The wire of the detachable snare is placed between both legs of the clip. (d) The
clip is applied to the edge of the mucosal defect. (e) Another clip is applied to the
opposite side of the mucosal defect in the same manner. (f) The snare is squeezed
gently, and the mucosal defect is approximated. (g) Additional clips are applied to
close the defect. (h) The defect is closed completely. (B) The mucosal defect at the
gastric angle is closed completely with a detachable snare and clips. From Lee BI, Kim
BW, Kim HK, Choi H, Ji JS, Hwang SM, et al. Routine mucosal closure with a detachable
snare and clips after endoscopic submucosal dissection for gastric epithelial neoplasms:
a randomized controlled trial. Gut Liver 2011;5(4):4549
[3].
Figure 8.9 Injector needle: (A) Retracted (up) and locked in working position (below);
(B) syringe connected to the external end of the probe. All from MITI.
shaft with the Bowden wire and the handling. The jaws are available in a
very wide range of designs (
Fig. 8.10).
Biopsy forceps are also available for so-called “hot biopsies” (tissue
retrieval with concomitant electrocautery). They are insulated.
Graspers are needed to grip tissue or foreign bodies. The function of
the jaws is always a trade-off between a firm grip and a gentle treatment
of the object.
Today, the industry provides numerous designs which are optimized to
the particular purpose (
Fig. 8.11).
Interventional Flexible Endoscopy
335
Figure 8.10 Various models of commercially available forceps with a central spike, various types of leg, and optional “hot biopsy.” (A) Round; (B) round with windows; (C)
round with spike; (D) round with windows and spike; (E) oval; (F) oval with windows;
(G) oval with spike; (H) oval with windows and spike; (I) oval, toothed; (J) oval with
spike, toothed; (K) oval with windows, rat-toothed; (L) round with windows, rotatable;
(M) oval with windows and spike, rotatable; (N) round, alligator; (O) round with windows, alligator; (P) round with windows, rat-toothed; (Q) round with windows, swiveling, rat-toothed; (R) round, hot biopsy. From Matsuda K, Tajiri H. Tissue and fluid
sampling. In: Classen M, Tytgat GNJ, Lightdale CJ, editors. Gastroenterological endoscopy, 2nd ed Stuttgart: Georg Thieme Verlag; 2010. p. 2039
[4].
Figure 8.11 Graspers: (A) Alligator jaw: ideal for small, solid objects such as clips; (B)
shark tooth: accurate and safe grip; (C) tripod: removal of polyps. All from MITI.
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Biomedical Engineering in Gastrointestinal Surgery
8.3 CLIPS
Clips are small, tweezer-like devices for tissue (mucosa) approximation.
They work by forcibly approximating the clip arms thus including a volume of tissue to achieve either vascular occlusion or closure of a defect.
8.3.1 Standard endoscopic clips
The first description of a clip used in GI endoscopy came from Japan in
1975
[5]. It was another 15 years until they really became popular when the
design of the delivery system was improved. The first significant step forward
came in the mid-1990s from Olympus (Tokyo, Japan) with the introduction
of the reloadable clip, followed by the preloaded QuickClip in 2002 and
rotatable QuickClip2 in 2005. Cook’s TriClip and Boston Scientific’s
Resolution clip both were launched in 2003 (
studies, investigators found that these clips had application times and failure
rates that were very similar and all achieved 100% hemostasis.
The design of clips is challenging, since the clinical requirements are
high. The users need preloaded clips with reliable deployment, good
mucosal adherence, adequate apposition and strength of the arms, rotatability, and a wide opening distance of the arms.
Clips are used as tissue markers or to stop bleeding by occluding vessel
stumps. They are even applied to occlude smaller perforations, but this
type of closure is insecure since the mucosa only is approximated.
Fig. 8.12). In two comparative
8.3.2 Over-the-Scope-Clip
The so-called “over-the-scope-clip” (OTSC) is an entirely new approach
to approximate tissue in full thickness. The system consists of an applicator cap with a mounted OTSC clip and the release accessories. The clip
Figure 8.12 (AC) Currently available hemoclips: From left to right: EZ clip
(Olympus, Tokyo, Japan), TriClip (Cook Medical, Bloomington, IN, United States),
Resolution Clip (Boston Scientific, Marlborough, MA, United States).
Interventional Flexible Endoscopy
Figure 8.13 (A) Open (1) and closed (2) OTSC clips. (B) The application procedure:
(1) targeting the lesion; (2) approximation of the application cap and the target tissue; (3) firing the clip; (4) procedure completed. All from Ovesco Endoscopy AG.
337
is a Nitinol ring with circular teeth. If it is released, two half-rings are
shaped which firmly compress the tissue which is placed in-between
them (
Fig. 8.13).
Using a specially designed bilateral grasper, the two edges of a fullthickness lesion of the wall can be positioned precisely to achieve reliable
compression.
The clip is licensed as a long-term implant, but most frequently it
leaves the human body within several months. Three different sizes of
caps are available, suitable for the majority of endoscopes. The main indication for OTSC clips are hemostasis and full wall occlusions, e.g., after
perforation
[6]. For the latter, several clips can even be placed in a row.
The introduction of this type of a clip certainly boosted once again
the clinical role of therapeutic endoscopy
[7].
The refinement of clip technology extended the range of clinical
applications considerably. They are no longer limited to stopping bleeding
or to occluding small perforations, but they can also be used to close fullthickness resection defects, fistulae, or to anchor stents
[8].
8.4 CLINICAL APPLICATIONS
8.4.1 Gastrointestinal Bleeding
Bleeding from the upper or lower GI tract is still today a significant cause
of mortality. Only a few decades ago, the treatment was a surgical
domain. Today, endoscopic therapy is the treatment of choice.
Endoscopic treatment can be broadly categorized into injection, thermal,
and mechanical methods.
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Biomedical Engineering in Gastrointestinal Surgery
Figure 8.14 GI bleeding: Injection therapy: (A) in an acute bleeding, the image
is often difficult to interpret since visualization is poor. The bleeding site is assumed
to be in the center of the image. (B) The injection cannula is introduced (left lower
corner) and the needle is inserted into the tissue (needle not visible). By
injecting epinephrine the bleeding is stopped (whitish area, arrow). Courtesy:
Prof. Dr. S. v. Delius, Klinikum rechts der Isar.
8.4.1.1 Injection Therapy
If epinephrine (Suprarenin) is injected into a bleeding artery or into the
vicinity of it, immediate vasoconstriction is initiated. In addition, the
mechanical effect of compression exerted by the injected fluid volume
contributes to hemostasis (
Fig. 8.14). Fibrin glue is another powerful
agent with a higher long-term effect.
Injection hemostatic therapy is mostly less focused than, e.g., clip
application and less long-standing. However, it is mostly a helpful option
in difficult emergency situations.
8.4.1.2 Thermal Hemostasis
Thermal approaches for hemostasis can be divided into contact methods
and noncontact methods.
8.4.1.2.1 Contact Methods
If bleeding tissue is compressed, the local effect of thermal energy is
reinforced (reduction of the “heat-sink” effect). The tissues, including the
vessels, are sealed by the sol/gel effect.
Direct contact probes exert direct, unilateral pressure onto the bleeding site (
Fig. 8.15). Even more effective are specially designed forceps/
graspers. If the bleeding structure is hit accurately, it both provides
mechanical tamponade and a targeted electrical current flow to provide
direct coagulation.
Interventional Flexible Endoscopy
Figure 8.15 Coaptive coagulation. (A) Firm compression by a contact thermal probe
stops the blood flow and reduces the heat-sink effect. Thermal energy is then
applied to seal the artery. (B) A 3.2-mm Heatprobe (Olympus CD-10Z) in a dual-channel therapeutic endoscope (Olympus GIF-2T240) with 3.7- and 2.8-mm channels).
Three irrigation ports are located 1 cm proximal to the Teflon-coated tip. Forceful targeted irrigation of an ulcer bed can be applied through these ports. From M. Scholle.
8.4.1.2.2 Noncontact Methods
339
Laser and argon plasma coagulation (APC) exert thermal energy to
opposed objects without contacting them. Theoretically, they should be
ideally suited to stop localized or diffuse bleedings. However, the initially
high expectations are not (yet) met in clinical reality.
Laser Coagulation
The term “laser” is the abbreviation of “light amplification by the
stimulated emission of radiation.” If living tissue is hit by a laser beam,
hyperthermic destruction with thermal contraction and coagulation
occurs.
However, the laser approach was soon overtaken by the widespread
use of lower cost and less cumbersome thermal devices. Today, the laser is
still used for lithotripsy of gallstones (Holmium laser)
[9].
Argon Beaming
Argon plasma coagulation (APC) is a noncontact monopolar electrosurgical technology. Electrical energy is transmitted via an ionized argon
gas (“plasma”) beam.
The probe is a flexible argon tube containing an electrode in the distal tip which ignites the plasma as soon as argon flows (see
Chapter 6.2.12.2: Argon Plasma Coagulation).
APC is effective agains t superficial bleeding of parenchymatous
organs, but less reliable in strong arterial bleedings. However, there
is no evidence to suggest that APC is superior to other endoscopic
therapies
[10].
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Biomedical Engineering in Gastrointestinal Surgery
Figure 8.16 Mechanical occlusion using the OVESCO clip: The clip is already closed.
Note the two halves (1, 2) of the clip. Courtesy: Prof. Dr. S. v. Delius, Klinikum rechts
der Isar.
8.4.1.3 Mechanical Methods
If technically feasible, a well-placed hemoclip is still the most effective
means to occlude reliably arterial vessels. In clinical practice, repetitive
clip applications are often required to achieve the desired hit. The amount
of tissue which is effectively compressed is rather small.
Even more effective than standard clip occlusion is the newly developed OTSC clipping method (Ovesco Endoscopy AG, Tuebingen,
Germany) (
Fig. 8.16).
Theoretically, suturing techniques would also be attractive, but the
first sufficiently fast and simple systems are just on the threshold to the
market (see Chapter 9.2.2.2: Suturing Devices).
8.4.2 Percutaneous Endoscopic Gastr ostomy
Frequently it occurs that patients become unable to eat and drink, e.g.,
caused by hypopharyngeal or esophageal tumors. In these cases, endoscopy is able to provide an external access to the stomach to enable enteral
nutrition. The technique of percutaneous endoscopic gastrostomy (PEG)
was developed about 20 years ago.
The idea of the PEG is to insert a feeding tube through the abdominal
wall into the stomach. Several steps are necessary. A gastroscope is positioned
into the stomach and the anterior wa ll of the stomach is illuminated. In most
cases, the light of the gastroscope can be seen through the abdominal wall.
Interventional Flexible Endoscopy
Figure 8.17 The tip of the endoscope is identified by external compression of the
abdominal wall. From MITI.
Figure 8.18 (A) Direct puncture of the stomach under endoscopic control;
(B) the guide is introduced; (C) the channel is appropriately dilated; (D) the catheter
is introduced through a split cannula. Courtesy: Prof. Dr. S. v. Delius, Klinikum rechts
der Isar.
341
At this very spot the observer compressestheabdominalwallwhichcanbe
clearly seen from within. It can be assumed no w that the anterior gastric
wall is immediately adjacent to the abdominal wall (
Fig. 8.17).
A hollow needle is inserted through the abdominal wall into the gastric
lumen and a thread is inserted. This thread is caught with biopsy forceps of
the endoscope and pulled out through the mouth (
Fig. 8.18).
Using the thread as a guide, the puncture site is dilated after skin incision by inserting bougies into the stomach. Thus, the channel is gradually
widened until it allows to insert the PEG catheter.
Alternatively, the feeding tube is attached to the oralad end of the
guide thread and drawn back until it appear s on the outer abdominal
wall. The position of the feeding tube is secured by a balloon which is
inflated within the gastric lumen.
By pulling the balloon gently against the abdominal wall, the puncture
site is sufficiently sealed to prevent leakage. After 710 days, a
stable channel is established which permits to exchange the catheter in
case of need (
Fig. 8.19).
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Biomedical Engineering in Gastrointestinal Surgery
Figure 8.19 (A) Schematic drawing of a PEG in situ. (B) Within the stomach:
Inflated balloon at the anterior gastric wall. Courtesy: (A) M. Scholle, (B) Prof. Dr. S. v.
Delius, Klinikum rechts der Isar.
8.4.3 Endoscopic Resection of Neoplastic Tissue
In premalignant lesions (e.g., polyps) or very early malignancy with no
risk of lymph node dissemination, a local excision is sufficient.
8.4.3.1 Snare Polypectomy
Pedunculated polyps are comparably easy to remove (
Fig. 8.20). An open
snare is placed over the polyp and closed. The wire loop closes concentrically toward the tip of the snare sheet and, thus, transects the base of the
tumor.
In case of doubt (if strong vessels are suspected in the pedicle), a
detachable loop can be placed underneath beforehand.
8.4.3.2 Endoscopic Mucosal Resection
If the endoluminal lesion is flat, the tangential endoscopic approach is significantly more difficult. The management of these findings is facilitated
by making them prominent by injecting fluid into the submucosal layer.
The fluid cushion makes the pathological area protrude into the lumen. It
now can be removed by a snare (
Fig. 8.21) or excised with a needle
knife.