Left-Sided Mediastinal Lymph Node Dissection—Video 22

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CHAPTER 22 Left-Sided Mediastinal Lymph Node Dissection—Video 22

Introduction

Mediastinal lymph node dissection is a critical part of any lung cancer operation. Lymph node dissection should be performed for all types of cancer resections (e.g., wedge, segmentectomy, lobectomy, pneumonectomy) to ensure proper tumor staging and for possible therapeutic benefit. Nodal dissection for left-sided resections should include station 5 (subaortic, between the aorta and left main pulmonary artery), station 6 (para-aortic, left side of the ascending aorta, and aortic arch), station 7 (subcarinal), station 8 (para-esophageal), and station 9L (inferior pulmonary vein). Video-assisted thoracic surgery (VATS) provides excellent visualization of the aortopulmonary window lymph nodes and has replaced anterior mediastinotomy (i.e., Chamberlain procedure) for biopsying nodes in this area at many institutions.

Approach to Video-Assisted Left-Sided Mediastinal Lymph Node Dissection

Order of Operative Steps

The lymph node dissection for right- and left-sided lung cancers can be performed after the parenchymal resection or can be performed before the resection, because node dissection can define the anatomy and make the lobectomy easier and because node dissection may identify stage III patients who would then undergo neoadjuvant treatment and lobectomy at another time. Exceptions include nodes in station 9, which are removed when the inferior pulmonary ligament is divided, and lymph nodes in station 10, which are usually dissected and removed just before division of the bronchus. Station 10 lymph nodes are not considered to be mediastinal nodes in the American lymph node mapping system, but they are mentioned here because unlike other N1 nodes, a standard lobectomy without a dedicated lymph node dissection may miss these nodes.

Key Points

♦ Carry out lymph node dissection through the standard VATS port sites using a 5- or 10-mm, 30-degree thoracoscope (Figure 22-1).

♦ With small ringed forceps, grasp the lymph nodes, which are friable and tend to disintegrate if only parts of them are grabbed. Alternatively, use a long Allis clamp to grasp the lymph nodes during the dissection.

♦ Dissect with standard electrocautery or an ultrasonic dissector. A partially covered Teflon-coated electrocautery can be used to avoid injury to surrounding structures. In some areas, adjacent structures may be at risk for injury during lymph node removal:

Station 7, the esophagus and mainstem bronchus: The vagus nerve should be left with the esophagus and can be used as a posterior landmark when dissecting in the level 7 area.

Station 9: To avoid esophageal injury during division of the inferior pulmonary ligament, keep the dissection close to the lung parenchyma. The inferior pulmonary vein is also at risk for injury during this dissection.

Stations 5 and 6: The left recurrent laryngeal nerve, left phrenic nerve, left main pulmonary artery, and aorta should be avoided.

♦ Bleeding from torn lymph nodes and bronchial arteries should be controlled with precise visualization and electrocautery. The errant use of “scorched earth” electrocautery is ill advised and is likely to lead to injury of adjacent structures. A small amount of surgical cellulose can be used to tamponade the bleeding, which promotes hemostasis and permits better visualization and control of any nodal vessels.

♦ Perform a complete lymph node dissection on all patients, and resist terminating the dissection when metastases are identified in one area.

Figure 22-1 Port site placement.

Video-Assisted Left-Sided Mediastinal Lymph Node Dissection (Video 22)

Step 1. Station 9 Nodes

♦ Exposure: The lung is retracted superiorly.

♦ Aim the thoracoscope posteriorly with the 30-degree lens pointed medially toward the ligament.

♦ Left-sided nodal stations 5, 6, 7, and 9 are included in the dissection.

♦ Remove station 9 lymph nodes while dividing the inferior pulmonary ligament.

♦ Retract the left lower lobe cephalad through the access incision or posterior port (Figure 22-2). A ringed forceps placed alongside the camera (through the same port) pushes the diaphragm down if it is impairing visualization of the pulmonary ligament.

♦ Divide the inferior pulmonary ligament with electrocautery through the access incision or inferior port (Figure 22-3).

♦ Station 9 lymph nodes become apparent as the ligament is divided and include nodes adjacent to the inferior pulmonary vein (Figure 22-4).

♦ The dissection is performed close to the lymph nodes to avoid injury to the esophagus and inferior pulmonary vein.

♦ During a left lower lobectomy, dissect bluntly along the inferior pulmonary vein to sweep the nodes toward the lung parenchyma and leave them adherent to portion of the vein that is being removed.

Figure 22-2 Retraction of the left lower lobe superiorly.

Figure 22-3 Division of the inferior pulmonary ligament.

Figure 22-4 Left station 9 lymph nodes.

Step 2. Station 5 and 6 Nodes

♦ Exposure: The lung is retracted inferiorly and posteriorly.

♦ Aim the thoracoscope inferiorly with the 30-degree lens pointed anterior and slightly down.

♦ The lymph node dissection for stations 5 and 6 may be performed after the lung resection. Alternatively, resection before the lobectomy can expose and define the anatomy of the vessels and facilitate the dissection of the vessels for the lobectomy (see Chapter 11).

♦ Station 5 lymph nodes are located in the subaortic space between the aorta and the left main pulmonary artery.

♦ Station 6 lymph nodes are the para-aortic lymph nodes and are located on the left side of the ascending aorta and aortic arch.

♦ Occasionally, large station 5 and 6 lymph nodes obscure the view of the left upper lobe pulmonary arterial branches and require removal during the parenchymal resection.

♦ Retract the lung inferiorly through the posterior port, and perform the dissection through the access incision.

♦ Grasp the edge of the pleura, near the left main pulmonary artery, and dissect the underlying lymph nodes away from the soft tissue for removal (Figure 22-5).

♦ Dissect close to the nodes to avoid injury to the phrenic nerve, recurrent laryngeal nerve, and the left main pulmonary artery.

♦ Remove the lymph nodes through the access incision with a small ringed forceps (Figure 22-6).

Figure 22-5 Left station 5 and 6 lymph nodes.

Figure 22-6 Removal of station 5 and 6 lymph nodes.

Step 3. Station 7 and 10 Nodes

♦ Exposure: Retract the lung anteriorly.

♦ Aim the thoracoscope inferiorly with the 30-degree lens positioned posteriorly and down.

♦ Through the posterior port site, access the station 7 lymph nodes in the subcarinal space.

♦ Gently retract the aorta and esophagus posteriorly with an endokittner placed through the posterior port to open up the subcarinal space.

♦ Grasp the lung through the anterior access incision and retract it anteriorly (Figure 22-7).

♦ With electrocautery, open the pleura on the posterior hilum along the inferior border of the left lower lobe bronchus and left main bronchus.

♦ Place a second ringed forceps through the access incision to retract the left main bronchus anteriorly.

♦ Visualize the station 7 lymph nodes in the subcarinal space between the aorta and the left main bronchus (Figure 22-8).

♦ Grasp the nodes with a ringed forceps through the access incision or posterior port, and divide the surrounding soft tissue attachments with electrocautery.

♦ Locate the station 10 lymph nodes at the tracheal-bronchial angle and along the main bronchus. Remove these lymph nodes from a posterior approach during the station 7 lymph node dissection.

Figure 22-7 Left lung is retracted anteriorly to expose the posterior hilum and subcarinal space.

Figure 22-8 Station 7 lymph node removal.

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Atlas of Minimally Invasive Thoracic Surgery (Vats)