胸腔镜下食管肌层切开术（图文演示）

中文版：胸腔镜下食管肌层切开术（中文图文演示）

THORACOSCOPIC   LOWER   ESOPHAGEAL   MYOTOMY
Authors
D Gossot
Abstract
The description of the thoracoscopic lower esophageal myotomy covers all aspects of the surgical procedure used for the management of achalasia.
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: exploration/exposure, establishing the myotomy, end of myotomy.
Consequently, this operating technique is well standardized for the management of this condition.

1. Introduction
Achalasia is most often treated by medical therapy before resorting to surgery.
Surgery is usually restricted to treating complications or failures in endoscopic dilatation.
Laparoscopic myotomy has become the surgical treatment of choice. However, when there is a high stenosis or if the abdominal route is contraindicated, a thoracoscopic approach may be indicated.

2. Anatomy
• Main relationships

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The thoracic esophagus is situated in the posterior mediastinum, below the mediastinal pleura. Its upper three fourths extends inferiorly in the right side of the thorax. After crossing in front of the aorta, it enters the left hemithorax. The upper two thirds of the esophagus should therefore be approached from the right and the lower one third from the left.

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The esophagus is successively in close contact with the following anatomical structures:
- the membranous wall of the trachea and the origin of the left main bronchus;
- the right pulmonary artery;
- the pericardium.

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The esophagus is successively in contact with the following anatomical structures:
- the rachis, from which it gradually separates starting from the fourth dorsal vertebra (D4);
- the thoracic aorta;
- the azygos vein;
- the thoracic duct, in the angle between the esophagus and the aorta.

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The esophagus is traversed by the arch of the azygos vein.
The rami of the right vagus nerve extend along its right side.

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The esophagus is mainly in contact with the aorta, the inferior pulmonary vein, and the left vagus nerve.

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All esophageal arteries are branches of the thoracic aorta, except in the superior aspect where the esophagus is supplied by branches of the inferior thyroid artery, and in the inferior aspect where it receives branches of the left gastroomental artery and the phrenic arteries.

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Because of the posterior mediastinal location of the esophagus, adequate retraction of the lungs is mandatory for exposure of the operative field, especially when a right thoracotomy is performed. Selective intubation is indispensable as manual retraction is not possible in thoracoscopy.
The lesions situated on the left edge of the upper two thirds of the esophagus must be approached only from the right. Consequently, exposure of the esophagus can only be achieved by rotating it. This rotation must be minimal, however, to avoid any risk of denervation.

• Danger areas

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Surgery for benign pathologies is performed in direct contact with the esophagus. Certain structures that are normally exposed in cancer surgery (thoracic duct, membranous wall of the trachea) are not well visualized in this surgical technique.

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The arch of the azygos vein is intimately related to the middle and upper thirds of the esophagus and can be easily injured during its dissection. It is imperative to check it before dissection, because any damage to it would be difficult to control by thoracoscopy.
The rami of the vagus nerve must be preserved if possible.

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Access to the esophagus may require freeing of the pulmonary ligament. Care must be taken to remain at a distance to avoid injuring the left inferior pulmonary vein at its superior pole.
The left vagus nerve must be preserved.

3. Indications
A Heller myotomy is performed via a laparoscopic or thoracoscopic approach. Most authors recommend laparoscopy, which may be combined with an antireflux procedure. The alternative thoracoscopic approach was popularized by Pellegrini et al. (1992), who perform it routinely, preferring it to laparoscopy. In 17 patients who were operated on using the thoracoscopic approach, the procedure failed in 3 of the early patients, who then underwent a second operation via an abdominal approach (1 laparotomy and 2 laparoscopies) (Pellegrini et al., 1992).

These failures occurred because the myotomy was not extended far enough onto the stomach. Though this can initially be a limiting factor for the technique, when performed by experienced surgeons, the stomach can easily be exposed using a thoracic approach. A fundoplication cannot be combined with this approach, however. In the series of Pellegrini et al., there were 2 cases of symptomatic reflux, objectively measured by pH-monitoring. According to the author, the low reflux rate is related to the fact that dissection of the gastroesophageal junction is less extensive in thoracoscopy than in laparoscopy. Maher (1997) reported similar findings: out of a series of 21 patients who underwent thoracoscopic surgery, only 1 case of clinical reflux was observed.

Laparoscopic access to the megaesophagus is still considered the approach of choice, especially when the surgeon combines an anti-reflux procedure with the myotomy (Pellegrini et al., 1992). In addition, patients generally tolerate laparoscopy better than thoracoscopy, which can cause persisting intercostal pain for a number of weeks postoperatively. Nevertheless, mastering the thoracoscopic approach is useful, especially for patients with a contraindication to the abdominal approach, or for whom a high myotomy is indicated (Shimi et al., 1992).

4. Operating room set-up

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As for any Heller procedure, the patient must be kept NPO at least 12 hours prior to surgery. If there is any doubt, an esophageal catheter must be placed preoperatively to avoid an inhalation injury during induction.
The left lung is excluded by a Carlens-type selective intubation catheter. Its correct position must be confirmed by fibroscopy. Other conditions include:
- lateral right decubitus with a slight forward tilt for better access to the posterior mediastinum;
- left arm hanging down allowing free movements of the endoscope and instruments (take care to protect the forearm with a drape to avoid the compression of the median nerve by the edge of the table);
- sandbag readily available, to be used in case of a conversion to thoracotomy: its use is not necessary if the procedure is performed by thoracoscopy alone.

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1. The surgeon stands behind the patient.
2. The assistant stands opposite the surgeon.
Both can view separate video monitors.

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1. Operating table
2. Anesthetic equipment
3. Thoracoscopic unit
4. Monitors
5. Instrument table
6. Large table

5. Trocar placement

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Certain surgeons operate under constant intraoperative endoscopic visual control. Use of a luminous bougie may also be helpful. With experience, however, these aids may no longer be required.
Three trocars are routinely used. A fourth trocar may be useful.

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A: The optical trocar is inserted posteriorly to anteriorly on the mid-axillary line in the sixth intercostal space.

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B: Operating
A 5 mm trocar is inserted on the anterior axillary line, in the fifth intercostal space, for the grasper, electrocautery hook, or scissors.
C: A 10 mm trocar is inserted on the posterior axillary line, in the seventh intercostal space, for the grasper or suction-irrigation device.

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D: A supplementary 5 mm trocar may be used when the diaphragm must be retracted using an atraumatic retracting device. It is inserted on the mid-axillary line, in low position, in the seventh intercostal space.

6. Instruments

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The instrumentation kit includes standard straight and curved thoracoscopic instruments.
The curved instruments are used only in case of unsuspected pleural adhesions.
As for all video-assisted thoracic surgery, a conventional thoracic surgery instrumentation kit must be available in the operating room in case of conversion.

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One 10 mm direct view (0°) scope is sufficient.
More so than for any other videoscopic procedure, an excellent video camera is necessary to correctly identify any residual muscle fibers or microperforation of the mucosa.

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7. Major principles
The aim is the same as for laparoscopic esophageal myotomies:
- to complete a myotomy at least 5 cm long on the thoracic esophagus and at least 1.5 cm long on the gastroesophageal junction;
- not to leave any residual muscle fibers;
- to preserve mucosa integrity.

Because the gastroesophageal junction is minimally mobilized by the left thoracic approach, an antireflux procedure is generally not necessary.

8. Exploration/exposure

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Correct retraction of the left lung ensures that the inferior lobe does not interfere with dissection.
In most cases, it is necessary to begin by freeing the pulmonary ligament.
The inferior lobe of the lung is retracted cephalad and posteriorly with a grasper. The ligament is divided using an electrocautery hook while taking care to remain at a distance from the inferior pulmonary vein.
The esophagus is partially revealed under the mediastinal pleura, in the groove formed anteriorly by the pericardium and posteriorly by the aorta.

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The mediastinal pleura is opened lengthwise, cephalad to caudad, with a pair of scissors, completely exposing the esophagus. It is important to achieve perfect hemostasis during this step as any oozing or bleeding would add to the difficulty of identifying the esophageal muscle fibers.

9. Establishing/myotomy

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Grasping the esophagus with a 10 mm grasper, the surgeon can easily identify the gastroesophageal junction moving cephalad. It may be helpful to also use an atraumatic retracting device to push the diaphragm downwards.

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The myotomy is begun approximately 4 cm above the gastroesophageal junction.
This is a delicate step for 2 reasons:
- the risk of damaging the mucosa,
- mild bleeding occurs frequently, interfering with the view.
It is preferable to begin opening the muscularis with scissors, using electrocautery set to low power. The mucosa, recognizable by its pearly white color, is gradually reached.

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The myotomy is extended caudally with Metzenbaum scissors using the same method as in the laparoscopic or open approach. Short periods of irrigation of the mucosa, followed by careful suction (to avoid bruising the mucosa) will maintain a clean operating field.
To pursue the myotomy cranially, it is preferable to use a diathermy or, even better, an ultrasonic hook. It is important not to coagulate until the muscularis has been sufficiently lifted off the mucosa.

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Intraoperative complication:
The only specific risk of complication involves injury to the esophageal mucosa.
For surgeons who are skilled in endoscopic sutures, it is possible to repair a perforation of the mucosa with one or several slowly absorbable sutures. It is advisable to reinforce the suture with biological glue.
Before resuming food intake, a contrast swallow and follow-through investigation is mandatory.