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304 Mediastinal lymph node dissection

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SUBCARINAL DISSECTION

The subcarinal dissection is begun by retracting the lung anteriorly. The pleura is opened in the posterior hilum in a caudal direction midway between the anterior border of the esophagus and the medial border of the bronchus intermedius beginning at the caudal margin of the azygos vein (Figure 4). The pleural edge overlying the esophagus is grasped and retracted posteriorly. After ligation and division of small branches of the vagus nerve and bronchial arteries crossing the subcarinal area, the right and left main stem, upper lobe, and bronchus intermedius are exposed with blunt

INFERIOR PULMONARY LIGAMENT DISSECTION

Lymph nodes along the length of the esophagus (paraesophageal nodes) from the level of the azygos vein to the

diaphragm are removed and labeled as level 8. Removal is accomplished by opening the overlying pleura. The inferior pulmonary ligament should be divided close to the lung, and any lymph tissue in the ligament should be removed and labeled as level 9. Level 11 (interlobar) and level 12 (lobar) lymph nodes are excised with the specimen and should be identiﬁed by the pathologist. This ﬁgure depicts the paraesophageal (level 8), inferior pulmonary ligament (level 9), and nonhilar (levels 11 and 12) mediastinal lymphadenectomy. The view is as by a right posterolateral thoracotomy. The numbers correspond with those explained in detail in Table 28.1.

The previously placed packs are removed, and hemostasis is double-checked. At the completion of the procedure, the lymph node dissection sites should be inspected again.

dissection. The ﬂoor of the dissection is the posterior pericardium, and it is carried superiorly until the carina is reached. Posteriorly, the lymph nodes are dissected off the esophagus. Care should be taken to preserve the vagus nerves. At the apex of the subcarinal triangle are several nourishing blood vessels of the subcarinal lymph nodes that need to be identiﬁed to ensure hemostasis before removing the subcarinal lymph node packet. I usually ligate these vessels rather than clipping them. These lymph nodes are labeled as level 7. A warm gauze pad can be placed in the subcarinal space to enhance hemostasis.

Phrenic nerve

Level 11 and 12 nodes

Azygos vein

Vagus nerve

Level 8 nodes

Inferior pulmonary vein

Level 8 nodes

Inferior pulmonary ligament

Level 9 nodes

COMPLETE LYMPH NODE DISSECTION FOR A LEFT THORACOTOMY

SUPERIOR MEDIASTINAL DISSECTION

The dissection is begun by incising the mediastinal pleura between the phrenic and vagus nerves. Lymph nodes between the phrenic and vagus nerves, anterior to the ascending aorta or the innominate artery, are removed and labeled level 6. For patients with documented tumors at stations 2L and 4L, the operation is usually best performed through a median vertical

sternotomy being the ﬂoor of dissection of the interaorticocaval groove. This strategy permits a complete exenteration of the anterosuperior mediastinum and the enclosed lymph node stations, as well as the resection of stations 2R and 4R and the subcarinal lymph nodes. Although they are more technically demanding, all major pulmonary resections can be safely made through the same incision except for resection of lower lobe tumors, for which a separate anterolateral thoracotomy in the ﬁfth space can be made.

AORTOPULMONARY WINDOW DISSECTION

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Dissection is continued into the aortopulmonary

window. The compartment between the aorta and the pulmonary artery should be cleared of lymph tissue and labeled as level 5. These lymph nodes are lateral to the ligamentum arteriosum and proximal to the ﬁrst branch of the left pulmonary artery. The recurrent laryngeal nerve is identiﬁed and preserved. Cautery should be avoided to prevent thermal injury to all these nerves. This ﬁgure depicts the aortopulmonary window (level 5), para-aortic (level 6), subcarinal (level 7), and paraesophageal (level 8) mediastinal lymphadenectomy in the left hemithorax.

Resection of stations 2L and 4L requires mobilization of the aortic arch and left tracheobronchial angle. Numbers correspond with those explained in detail in Table 28.1.

Superior intercostal vein

Level 6 nodes

Left superior pulmonary vein

Phrenic nerve

Heart

Postoperative care 305

Vagus nerve

Level 5 nodes

Left pulmonary artery

Left main bronchus

Level 7 nodes

Aorta

Level 8 nodes

Left inferior pulmonary vein

SUBCARINAL DISSECTION

The entire lymph node packet underneath the left main stem bronchus, down to the right main stem bronchus, should be removed and labeled as 7 (subcarinal lymph nodes). In the subcarinal area, the dissection is begun by retracting the lung anteriorly and opening the pleura lying between the esophagus and the main bronchus. The only difference from the right side dissection is that the subcarinal space lies deeper on the left than on the right, which renders the access more laborious. A warm gauze pad can be placed in the subcarinal space to enhance hemostasis.

HILAR DISSECTION

Anteriorly, along the left main stem bronchus, between the carina and the left upper lobe bronchus, lymph nodes that are within the left pleural cavity are removed and labeled 10L. These are intrapleural lymph nodes (N1) medial to the ligamentum. Dissection should be continued proximally along the left main bronchus to the tracheobronchial angle, and after division of the ligamentum arteriosum; these mediastinal nodes are removed and labeled 4L.

removed and labeled as level 8. Care should be taken to carefully dissect the overlying pleura between the esophagus and aorta, especially when the normal anatomical relations are distorted by concurrent inﬂammation or tumor modiﬁcations. The previously placed packs are removed and hemostasis is double-checked. At the completion of the procedure, the lymph node dissection sites should be inspected again.

Extended lymph node dissection

The extended lymph node dissection includes the following in addition to the steps described for the radical lymphadenectomy. On the right, all soft tissue lying in the superior mediastinum and in front of the SVC up to both brachiocephalic veins is removed; the right subclavian artery, right recurrent nerve, and ascending aorta are skeletonized; and the thoracic ductus is ligated. On the left, stations 2 and 4 are removed after dissection and division of the ligamentum arteriosum and mobilization of the aortic arch. Supraclavicular lymphadenectomy is performed.

INFERIOR PULMONARY LIGAMENT DISSECTION

The inferior pulmonary ligament is divided, and all lymph nodes included in it are completely removed and labeled as level 9L. All lymph nodes along the esophagus (paraesophageal nodes) from the aortic arch to the diaphragm are

POSTOPERATIVE CARE

Although complications can potentially occur after a complete mediastinal dissection, with careful attention to all technical details, the morbidity of the procedure is minimal and is

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not signiﬁcantly different from that observed after systematic node sampling. The only major complications observable in patients who have neoadjuvant therapy before surgery is the likelihood of developing lung edema after removal of all ipsilateral and contralateral lymph node draining stations. Adequate intra- and postoperative ﬂuid restriction, however, can minimize this problem.

OUTCOME

A multicenter randomized trial has shown that, mediastinal systematic sampling was as efﬁcacious as complete mediastinal lymph node dissection in staging patients with NSCLC. However, complete mediastinal lymph node dissection identiﬁed signiﬁcantly more levels of N2 disease, and complete mediastinal lymph node dissection was associated with improved survival with right NSCLC when compared with systematic sampling in patients with stage II and IIIa tumors. Whether complete mediastinal lymph node dissection is superior to node sampling for patients with N0 or N1 (less than hilar) disease is currently being investigated in an open

randomized trial sponsored by the American College of Surgeons Oncology Group.

FURTHER READING

Berlangieri SU, Scott AM. Metabolic staging of lung cancer. New

England Journal of Medicine 2000; 343: 290–2.

Hata E, Hayakawa K, Miyamoto H, et al. Rationale for extended

lymphadenectomy for lung cancer. Thoracic Surgery 1990; 5: 19–25.

Keller S, Adak S, Wagner H, Johnson D. Mediastinal lymph node

dissection improves survival in patients with stages II and IIIa nonsmall lung cancer. Annals of Thoracic Surgery 2000; 70: 358–65.

Lung Cancer Study Group. Randomized trial of lobectomy versus limited

resection for T1 N0 non-small cell lung cancer. Annals of Thoracic Surgery 1995; 60: 615–23.

Mountain CF, Dresler CM. Regional lymph node classiﬁcation for lung

cancer staging. Chest 1997; 111: 1718–23

Naruke T. Signiﬁcance of lymph node metastases in lung cancer.

Seminars in Thoracic and Cardiovascular Surgery 1993; 5: 510–18.

Watanabe Y, Shimizu J, Tsubota M, Iwa T. Mediastinal spread of

metastatic lymph nodes in bronchogenic carcinoma. Chest 1990; 97: 1059–63.

https://t.me/med1917

The pericardium

JOHN C. KUCHARCZUK MD

Assistant Professor of Surgery, Division of Cardiothoracic Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA, USA

HISTORY

Throughout antiquity, the pericardium and heart were considered “off limits” by physicians. In 1766 Morgagni described the entity we now refer to as cardiac tamponade. This condition was recognized as usually fatal, and no interventions were attempted. In 1801, Francisco Romero performed the ﬁrst pericardial procedure for “hydropericardio.” Romero did not report his experience until 1815 when he presented two pericardial drainage procedures and ﬁve open pleural drainage procedures to the Society of the School of Medicine in Paris. Baron Dominique-Jean Larrey, Napolean’s chief surgeon, is credited with performing and reporting the ﬁrst surgical procedure on the pericardium in 1810, 5 years prior to Romero’s presentation in Paris. The American surgeon Claude Schaeffer Beck recognized the clinical triad of high venous pressure, hypotension, and distant heart sounds associated with cardiac tamponade in 1935. This constellation of ﬁndings is referred to as Beck’s triad.

Modern surgeons are presented with a number of diagnostic and therapeutic options in dealing with pericardial effusions, pericardial tamponade, and constrictive pericardial processes. This chapter will review the surgical approaches to the pericardium including subxiphoid pericardial window, thoracoscopic-assisted pericardial window, and transsternal pericardial resection. Special attention will be directed towards the indications for selecting one approach over another.

PRINCIPLES AND JUSTIFICATION

The goals of performing the pericardial window are: to relieve impending tamponade; to determine the underlying cause for ﬂuid in the pericardium; and to prevent the re-accumulation of ﬂuid. Thus, a surgical pericardial window can be diag-

nostic, therapeutic, or both. In the setting of penetrating trauma to the chest with subsequent concern for cardiac injury, the presence of blood in the pericardium during the performance of a pericardial window conﬁrms the diagnosis of cardiac injury and the need for cardiac repair. In patients with advanced malignancy, relief of impending cardiac tamponade due to a malignant pericardial effusion can be life saving, and obliteration of the pericardial space can result in signiﬁcant palliation. In patients with infected pericardial collections, drainage can result in isolation of the offending pathogen and guide antimicrobial therapy.

The pericardium is composed of ﬁbrous tissue and a serosal surface. A potential space exists between the serosal surface of the pericardium and the epicardium of the heart. Accumulation of ﬂuid within this potential space causes increasing intrapericardial pressure and results in compression of the lower pressure right heart with overall decreased cardiac ﬁlling. This pathophysiology accounts for the clinically observed pulsus paradoxus consisting of a fall in arterial pressure of greater than 10 mmHg during inspiration. The diagnosis of impending cardiac tamponade can be made on clinical grounds (Beck’s triad), although imaging studies are almost always obtained for conﬁrmation prior to surgery. The echocardiogram has become the standard for diagnosis of pericardial ﬂuid and impending pericardial tamponade. A conﬁrmatory study includes: diastolic compression or collapse of the right atrial or ventricular wall, leftward shift of the ventricular septum during inspiration, and an inspiratory decrease in left ventricular size. Small pericardial effusions which accumulate rapidly are often symptomatic. This situation occurs when the elastic limit of the pericardium is exceeded, and the intrapericardial pressure rises quickly. By contrast, effusions that accumulate slowly over long periods of time, such as those with renal failure, may reach very large sizes without symptoms. This scenario occurs because the

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pericardium slowly stretches, thus minimizing the increase in intrapericardial pressure and the hemodynamic effects of the effusion.

Constrictive pericarditis results from chronic inﬂammation with ﬁbrosis of the pericardium. Often, the serosal surface of the pericardium fuses to the epicardium of the heart and calciﬁes. This fusion results in compression of the ventricles with impaired diastolic ﬁlling. Patients are usually symptomatic with shortness of breath, hepatomegaly, abdominal ascites, and lower extremity edema. In advanced cases myocardial atrophy and ﬁbrosis occurs. Differentiating constrictive pericarditis from restrictive myocardial ﬁbrosis can be difﬁcult. Nevertheless, the distinction is of paramount importance as patients with restrictive myocardial ﬁbrosis will not beneﬁt from pericardial resection.

ANESTHESIA

The safe induction of anesthesia in patients with impending tamponade can be challenging for the patient, surgeon, and anesthesiologist. When required, the subxiphoid pericardial window can be performed under local anesthesia with light sedation; the alternative approaches to the pericardium require a general anesthetic. The hypotension associated with the induction of traditional anesthetics can result in complete cardiovascular collapse and death. For patients with impend-

ing tamponade, we select a subxiphoid approach. The patient is prepared for surgery awake with the head of the bed elevated 45 degrees. The operating surgeon is scrubbed, and a pericardiocentesis needle is available for emergency use prior to the administration of any anesthesia. Induction agents such as etomidate are selected for their minimal hemodynamic effects. Once the patient is anesthetized, the airway is secured and the procedure completed. Performing a pericardial window for impending tamponade requires cooperation and communication between the anesthesiologist and operating surgeon.

For patients without impending tamponade, alternative surgical approaches may be chosen. A video-assisted thoracoscopic procedure may be indicated in patients with a concomitant pleural effusion or those with a failed prior subxiphoid window. This approach requires a general anesthetic and placement of either a double-lumen endotracheal tube or bronchial blocker for isolated lung ventilation. Following induction of anesthesia and control of the airway, the patient must be repositioned into the lateral decubitus position for the procedure.

Those patients with constrictive pericardium are approached via a median sternotomy under general anesthesia. Most pericardectomies are performed without the aide of cardiopulmonary bypass; nevertheless, it should be immediately available should a coronary artery or signiﬁcant myocardial injury occur.

OPERATION

Subxiphoid pericardial window

The patient is positioned in a supine manner with both

arms tucked. The procedure can be performed under local anesthesia if needed, though most are performed under a general anesthetic. A 4 cm incision is centered over the xiphoid process. Electrocautery is used to achieve hemostasis in the subcutaneous tissues and dissect down directly onto the xiphoid. Care is taken to avoid inadvertent entry into the peritoneal cavity.

Skin incision

Operation 309

Sternum (Xiphoid excised)

Pericardium

Diaphragm

Cut edge of pericardium

Pericardial window

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Exposure is improved by the routine removal of the

xiphoid process. The tip of the xiphoid is grasped with a Kocher clamp, mobilized completely with electrocautery, and removed with heavy scissors. A small self-retaining retractor is used to retract the subcutaneous tissues. The pericardium is often covered with a layer of adipose tissue. Dissection is continued until the pericardial membrane is visualized. Exposure is aided by downward traction applied by a “sponge on a stick.” In patients with signiﬁcant pericardial effusions the membrane appears tense and bulging. The pericardium is grasped, and a 1 cm incision is made with a scalpel. The cut edge is grasped, and a large rectangular portion of the pericardium is removed with a scissors. The pericardial tissue and pericardial ﬂuid samples are sent to pathology and to microbiology for further analysis. A ﬁnger is introduced into the pericardium to assess for tumor implants and to break up any loculation.

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A 28 French right angled chest tube is placed through a

separate stab incision and directed into the pericardium. The wound is closed in layers with special attention to closure of the linea alba to avoid future epigastric hernia formation. The tube is placed to suction and remains in place for 4–5 days to effect obliteration of the pericardial space by sclerosis. Adjuvant use of sclerosing agents is not required.

Pericardial window

Diaphragm

In patients with penetrating thoracic trauma, a blue pericardial membrane conﬁrms the presence of pericardial blood and should prompt conversion to median sternotomy.

Video-assisted thoracoscopic pericardial window

Patients selected for a video-assisted thoracoscopic pericardial window should be hemodynamically stable and must be able to tolerate single lung ventilation. As the initial approach to a symptomatic pericardial effusion, the thoracoscopic approach has no role. The value of a thoracoscopic approach is the ability to examine, biopsy, and treat associated pleural or parenchymal lung processes. A thoracoscopic approach is also of beneﬁt in patients who recur with loculated posterior pericardial effusions following a subxiphoid approach and echocardiographic evidence of obliteration of the anterior pericardial space.

The patient is positioned supine, and general anesthesia is induced. A double-lumen endotracheal tube or bronchial blocker is positioned for isolated lung ventilation during the

Angled tube in pericardium

procedure. Once the airway is secured, the patient is placed in a lateral decubitus position, and the table is ﬂexed. Thoracoscopic pericardial window creation has been described from both the right and left chest. In our experience, visualization is much better and the procedure much easier when performed from the right side. Ultimately, the side for thoracoscopic approach is dictated by the associated pathology, for example an associated pleural effusion which needs to be drained.

A 3 cm incision is made overlying the eighth intercostal space in line with the anterior superior iliac spine. Electrocautery is used to achieve hemostasis in the subcutaneous tissues. Isolated lung ventilation is begun, and the airway on the operative side is opened to atmospheric pressure. The pleural cavity is entered with a dissecting ﬁnger to avoid lung injury. The thoracoscope is introduced and pleural examination carried out. Two additional working port sites are made, one in the ﬁfth intercostal space just below the tip of the scapula and one more anteriorly in the third intercostal space. The thoracoscope is moved to the ﬁfth intercostal space site.

The lung is allowed to fall posteriorly by slightly rotating

Right phrenic nerve

Thoracoscope with video camera

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the table. The phrenic nerve is identiﬁed and protected throughout its course. A location anterior to the phrenic nerve is selected; the pericardium is grasped and incised. The cut edge is grasped, and ﬂuid samples are obtained. A large rectangular portion of the pericardium is removed with an endoscopic shear. A chest tube is placed through the camera port site and directed across the pleural cavity and into the pericardial window. Alternatively, separate pericardial and pleural tubes can be placed. Bilateral lung ventilation is resumed, and the port sites are closed. The pericardial tube remains in place for 4–5 days on suction and then is removed. As with the subxiphoid approach, the success of this procedure relies on drainage of the pericardium with subsequent obliteration of the pericardial space by sclerosis.

Operation 311

Transsternal pericardiectomy for constrictive pericarditis

The patient is positioned in a supine manner with both arms tucked. A roll is placed under the shoulders. A median sternotomy incision is made, and the thymus gland is resected. Cardiopulmonary bypass is not routinely used but is immediately available should a malignant arrhythmia occur or if a coronary artery is injured.

A small incision is made in the pericardium with a scalpel to the left of the anterior descending coronary artery. The incision is very carefully deepened to the level of the myocardium, and a dissection plane is established. Release of the left heart prior to the right ventricle is important to avoid pulmonary edema.

312 The pericardium

Thickened pericardium

Diaphragm

Pericardium removed from anterior left ventricle

Left phrenic nerve

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Dissection is continued in a lateral fashion to the border

of the left phrenic nerve; the phrenic nerve is preserved; and the strip of pericardium elevated from the anterior left ventricle is removed.

Atrioventricular groove

Right atrium

Right ventricle

Next, the inferior portion of the left ventricle is released

by establishing a plane between the myocardium and diaphragm. Following this maneuver, the right ventricle is released up past the atrioventricular groove.