远端胃癌根治术（图文演示）

中文版：远端胃癌根治术（中文图文）


DISTAL   GASTRECTOMY   FOR   CANCER
Authors
N Tanigawa
Abstract
The description of the distal gastrectomy for cancer covers all aspects of the surgical procedure used for the management of gastric cancer.
Operating room set up, position of patient and equipment, instruments used are thoroughly described. The technical key steps of the surgical procedure are presented in a step by step way: identification, greater curvature, duodenal transection, lesser curvature, laparotomy, dividing the stomach, gastroduodenostomy.
Consequently, this operating technique is well standardized for the management of this condition.

1. Introduction
A laparoscopic gastrectomy to treat cancer is a demanding operation, and is not yet performed routinely. A proximal, distal or total gastrectomy associated with lymph node dissection of Group 1 and 2 nodes (D2 dissection) is defined as the standard operation for gastric cancer by the Japanese Gastric Cancer Association (JGCA, 1998). This is based on evidence of the significant prognostic impact of lymph node dissection. However, there is no consensus on whether D2 dissection should be recommended with a laparoscopic gastrectomy. This technique is described as an option for cancers up to Stage IA (T1N0) or Stage IB (T2N0) by the JGCA Treatment Guidelines (2001).

2. General anatomy

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The stomach occupies most of the left subphrenic space, with its upper third in the left subcostal space. Five sixths of the stomach are located to the left of the midline. In general, the esophagogastric junction is at the level of the 12th thoracic vertebra and the pyloric junction is at the level of the first lumbar vertebra.
1. Esophagogastric junction
2. Ventral peritoneum
3. Phrenogastric ligament
4. Gastrosplenic ligament
5. Greater omentum (gastrocolonic ligament)
6. Lesser omentum

• Anatomical classification

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The stomach is anatomically divided into 3 parts by the Japanese Gastric Cancer Association (JGCA, 1998); the upper (U), middle (M) and lower (L) stomach. The tumor is described in the order of the degree of anatomical involvement (eg LM or UML), and extension into the esophagus or the duodenum is recorded as E or D, respectively.
E: Esophagus
U: Upper
M: Middle
L: Lower
D: Duodenum

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According to the TNM classification, the stomach is divided into 4 parts by the International Union Against Cancer (UICC, 1997).
Ca: Cardia
F: Fundus
Co: Corpus
A: Antrum
P: Pylorus

• Vagal innervation

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Anterior/left vagal trunk:
Gastric branches from the left and right vagal trunks are responsible for parasympathetic innervation of the stomach. With fetal gastric rotation, these come to occupy an anterior and posterior position near the lesser curvature. The anterior vagus nerve sends branches to the liver, gallbladder and gastric antrum in addition to gastric branches to the anterior wall of the upper and middle stomach that comprise the anterior nerve of Latarget.
1. Hepatic branch
2. Pyloric branch
3. Anterior nerve of Latarget

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Posterior/right vagal trunk:
The vagal trunks at the gastroesophageal level are often multiple, and the posterior trunk may lie behind the esophagus in the mediastinal tissues. For this reason, it is easily missed by the surgeon not completely familiar with a vagotomy. The posterior vagus nerve sends a large branch to the celiac plexus and the celiac branch in addition to small gastric branches to the posterior wall of the upper and middle stomach that comprise the posterior nerve of Latarget.
1. Celiac branch
2. Posterior nerve of Latarget

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The musculature of the stomach is grouped in 3 layers: longitudinal muscle in the outermost layer, oblique running muscle in the intermediate layer which is lacking in the antrum, and circular muscle in the innermost layer. Circular muscle thickens to about 5 mm in width to form the pyloric sphincter muscle. There is no sphincter muscle at the esophagogastric junction.
1. Longitudinal muscle
2. Oblique muscle
3. Circular muscle

3. Vascular anatomy - I

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Gastric arterial blood supply comes from the celiac trunk, which originates from the anterior aspect of the aorta above the superior aspect of the pancreas. The trunk divides into 2 pedicles each at the lesser and greater curvatures. The pedicles then join a wide anastomotic network that supplants vascular blood supply when one of the main trunks is either obstructed or ligated. The celiac trunk is 1 cm to 3 cm long and divides into 3 branches which include:
1. the left gastric artery
2. the common hepatic artery
3. the splenic artery.

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a Left gastric artery
The left gastric artery originates from the celiac trunk in 90% of cases.

b Left gastric artery
In some patients, it originates:
1. directly from the aorta;
2. from the inferior phrenic artery;
3. from the gastrosplenic trunk;
4. from the gastrohepatic trunk.

c Left gastric artery
It completes an arch before joining and running along the lesser curvature 2 fingerbreadths below the cardia. It then divides into an anterior (a) and posterior (b) branch that both run down along the lesser curvature to join the terminal branches of either the right gastric artery or pyloric artery.

d Left gastric artery
The left gastric artery gives off several possible branches:
1. the hepatic artery (present and functional in only 10-20% of cases);
2. the anterior and posterior cardioesophageal arteries (supplying the cardia and abdominal esophagus).

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a Right gastric artery
The right gastric artery usually originates from the common hepatic artery.

b Right gastric artery
In some patients, it originates directly from:
1. the gastroduodenal artery;
2. the left hepatic artery;
3. the common hepatic artery.

c Right gastric artery
The right gastric artery joins the pylorus to become one of its main terminal branches. It then divides into anterior and posterior gastric branches that join the end of the left gastric artery at the junction between the horizontal and vertical parts of the lesser curvature of the stomach.
The right and left gastric arteries comprise the vascular arch of the lesser curvature.

4. Vascular anatomy - II

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The first part of the duodenum is vascularized by branches that mainly originate from the gastroduodenal artery.
1. Gastroduodenal artery

• Greater curvature

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The greater curvature of the stomach is bordered by the greater omentum and the gastrosplenic ligament. Each is composed of 2 layers continuous with the gastric visceral peritoneum. The greater omentum spreads over the transverse colon and extends beyond it inferiorly at the level of the body and horizontal region of the stomach, where it forms the gastrosplenic ligament at the level of the fundus. The right and left gastroepiploic arteries and the short gastric vessels form the vascular arch that runs through the anterior layer of the greater omentum.

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The right gastroepiploic artery:
a. originates from the division of the gastroduodenal artery at the inferior aspect of the duodenum.
b. runs along the greater curvature of the stomach from right to left at an average distance of 1 cm.
c. has branches that run along the anterior and posterior aspects of the stomach and into the omentum.

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The left gastroepiploic artery is a branch originating from the division of the splenic artery. It supplies the middle part of the greater curvature and runs through the gastrocolic ligament to join the terminal branches of the right gastroepiploic artery.
The right and left gastroepiploic arteries thus form the vascular arch of the greater curvature.
1. Left gastroepiploic artery

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The short gastric vessels originate from the terminal branches of the splenic artery. Alternatively, they originate either directly from the trunk of the splenic artery or from its terminal branches.
There are 2 to 6 vessels that run from the splenic hilum to the stomach via the gastrosplenic omentum. The largest vessel (the posterior gastric artery) joins the posterior aspect of the stomach and divides to supply the fundus and the cardia.
An avascular window of only 2 peritoneal layers is situated between the last short gastric vessel and the origin of the left gastroepiploic artery. These layers split to form the omental bursa opposite the splenic artery.
1. Gastric vessels

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Each gastric vein runs together with an artery of the same name in the perigastric area. Gastric veins, which all drain into the portal vein, are easily dilated by the portal pressure because of the lack of venous valves. The left gastric vein receives blood from the lesser curvature of the upper part of the stomach, runs along the left gastric artery in the gastropancreatic fold, and drains into the portal trunk in 60% to 70% of cases and into the splenic vein in 30% to 40% of cases.
1. Portal vein

5. Lymph node system

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The regional lymph nodes of the stomach are located along the corresponding veins.
However, there are significant differences in the definition of lymph node metastasis under the UICC (1997) and JGCA (1998) staging systems.

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JGCA (1998) classifies the regional lymph nodes of the stomach by anatomical location, numbering them from 1 to 20. Numbers 110, 111 and 112 of the lower mediastinal lymph nodes are also noted. These lymph nodes are grouped into the categories N1, N2, and N3, the combinations of each depending on the location of the primary tumor (upper, middle or lower stomach). The surgical intervention (lymph node dissection along with gastric resection) is described as D0-D3 resection. D0 implies no node dissection; D1, D2, D3 call for N1, N2, N3 dissection, respectively.

• Regional lymph nodes

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[flash=550,500]http://www.dxye.com/swf/Group 1.swf[/dplayer]

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[flash=550,500]http://www.dxye.com/swf/Group 2.swf[/dplayer]

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[flash=550,500]http://www.dxye.com/swf/Group 3.swf[/dplayer]

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[flash=550,500]http://www.dxye.com/swf/Group 4.swf[/dplayer]

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[flash=550,500]http://www.dxye.com/swf/Group 5.swf[/dplayer]

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The regional lymph nodes are the perigastric nodes along the lesser and greater curvatures, the nodes along the left gastric, common hepatic, splenic and celiac arteries, and the hepatoduodenal nodes. Involvement of other intra-abdominal lymph nodes such as retropancreatic (No. 13 with JGCA), mesenteric (No. 14 with JGCA), and para-aortic (No. 16 with JGCA) is classified as distant metastasis. In contrast to the JGCA system, in the TNM system the extent of lymph node metastasis is based on the number of lymph nodes involved: N0 (no extension to regional nodes), N1 (1-6 regional nodes), N2 (7-15 regional nodes), N3 (>15 regional nodes), NX (unknown). Rather than the size and location, it is the degree of penetration of the gastric wall by the primary tumor that is important. This is assigned a T-value.

6. Indications
The indications for laparoscopy-assisted distal gastrectomy are:
a)        Tumor located in the middle or lower third of the stomach;
b)        Tumor which has not progressed beyond the muscularis propria of the stomach;
c)        No evidence of macroscopic lymph node metastasis;
d)        Tumor not indicated for endoscopic mucosal resection or laparoscopic local resection.
A history of upper abdominal surgery is not an absolute contraindication. Neither tumor size nor pathological findings are among the selection criteria.

When the tumor is confined to the mucosal layer, prevalence of lymph node metastasis is negligible. However, when the tumor invades the submucosal layer (T1), the incidence of lymph node metastasis is generally 18%, while metastasis to Group 2 lymph nodes is found in very selected cases (Sasako et al., 1997). Therefore in oncologic laparoscopic surgery, for submucosal or deeper gastric cancer, lymph node dissection of both Groups 1 and 2, namely D2, seems necessary. When the tumor invades the layer of muscularis propria (T2mp), lymph node metastasis can be found in Group 3 nodes in selected cases, with an incidence of less than 2% (Sasako et al., 1997). When the tumor depth is confined to the subserosal layer (T2ss), a high incidence of lymph node metastasis can be found in Group 3. At present, laparoscopic lymph node dissection seems feasible up to D2 in some Japanese institutions. Taken together, a good indication for laparoscopic oncologic gastrectomy would be cancer at an early stage (T1), and a relative indication would be cancer invading the muscularis propria. If the tumor invades the subserosal layer or deeper (T2ss or T3), laparoscopic gastrectomy would no longer be indicated.

7. Operating room set-up

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- general anesthesia;
- orotracheal intubation;
- modified lithotomy position;
- nasogastric tube;
- supine position;
- arms at a right angle and legs apart (alternatively, arms alongside the body);
- reverse Trendelenburg position with a 10° or 30° tilt;
- dual-lumen gastric tube (used to totally empty the stomach);
- urinary catheter (optional).

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1. The surgeon stands between the patient's legs.
2. The first assistant stands on the patient's right.
3. The second assistant stands on the patient's left.
4. The scrub nurse stands behind and to the right of the surgeon.

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1. M1
2. M2
3. Anesthetic equipment
4. Operating table

8. Trocar placement

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The pneumoperitoneum is obtained by introducing the first trocar under direct visual control. This trocar is placed in the umbilicus.
The peritoneal cavity is insufflated with CO2 at a pressure of 10-12 mm Hg.
Exposure is aided by the 10° to 30° tilt of the operating table.

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A: 12 mm, in the umbilicus
B: 5 mm, right midclavicular line below the costal margin
C: 5 mm, left midaxillary line below the costal margin
D: 12 mm, left midclavicular line at the umbilicus
E: 5 mm, right midclavicular line 2-3 cm above the umbilicus

9. Instrumentation

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Trocar A: 30° laparoscope or optional 0° laparoscope

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Trocar B and trocar C:
1. Atraumatic grasper
2. Diathermy scissors
3. Monopolar/bipolar scissors
4. Suction-irrigation device

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Trocar D:
1. Dissecting hook
2. Diathermy scissors
3. Monopolar/bipolar scissors
4. Suction-irrigation device
5. Linear stapler
6. Needle-holder

Trocar E:
7. Grasper