The widespread use of high-resolution chest computed tomography (CT) has led to more frequent identification of small malignant pulmonary nodules. As the population ages, small peripheral lung cancers are frequently diagnosed in older patients with significant cardiopulmonary co-morbidities. Although sublobar resection has historically been reserved for patients with inflammatory or infectious disease states, such as bronchiectasis and tuberculosis, there has been a resurgent interest in its role for treating primary lung cancer patients with compromised cardiopulmonary function. Sublobar resection is also useful for the management of isolated pulmonary metastases such as occurs in sarcoma or colon cancer.
Anatomic segmentectomy is defined as the resection of a discrete portion of pulmonary parenchyma served by a specific segmental bronchovascular unit. Anatomic segmentectomy was proposed as a treatment of primary lung cancer in a review of 125 such procedures performed over a 12-year period. A 5-year actuarial survival rate of 56% was reported. These findings led to a debate regarding the utility of anatomic segmentectomy in treating lung cancer. The most widely accepted recommendations regarding the treatment of early-stage lung cancer came from the Lung Cancer Study Group, which reported higher local recurrence rates associated with sublobar resection. Landreneau and colleagues duplicated these results 2 years later. Despite a wide acceptance of lobectomy over sublobar resection, anatomic segmentectomy has become more common as a result of aggressive CT screening programs in Japan and the increased use of CT in the United States. Some series have reported 5-year survival and local recurrence rates similar to that of lobectomy.
Step 1
Surgical Anatomy
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Anatomic segmentectomy requires a thorough knowledge of the three-dimensional segmental bronchovascular relationships. During right upper lobe resections, the segmental vein is divided along the anterior hilum. The right upper lobe bronchus and its segmental branches are the most superior and posterior hilar structures. The segmental bronchus usually lies immediately posterior to the corresponding artery. The superior segmental artery lies opposite the middle lobe artery on the right and the lingular artery on the left. The inferior pulmonary vein subdivides into a basilar and superior segmental tributary. This arrangement should be considered when performing a lower lobe segmental resection because sacrifice of the entire inferior pulmonary vein will preclude anatomic segmentectomy.
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The left upper lobe vascular anatomy is the most variable of all lobes relative to size and number of segmental arteries. Although the left upper lobe segmental arterial branches are the most superior hilar structures, their exposure is facilitated by upper lobe vein division. The lingular artery may arise as a single large vessel or, more commonly, as two medium-sized trunks. Nodal tissue is often interposed at bifurcation points at the segmental level. Careful nodal resection often reveals adjacent segmental arteries and bronchi.
Step 2
Preoperative Considerations
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The preoperative workup for patients undergoing anatomic segmentectomy mirrors that of patients undergoing lobectomy.
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High-resolution chest CT provides the target lesion size and location, which indicates resectability. CT and positron emission tomography scanning may be used to determine the need for mediastinoscopy to aid in pathologic staging.
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Patients with abnormal pulmonary function testing may require quantitative ventilation/perfusion scanning or exercise testing. Stress echocardiogram testing may identify patients with significant cardiac ischemia or ventricular dysfunction.
Step 3
Operative Steps
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Perioperative management includes flexible bronchoscopy to rule out endobronchial abnormalities and to confirm double-lumen tube or bronchial-blocker positioning. Patients are positioned in a semilateral decubitus position for vertical axillary thoracotomy and thoracoscopy.
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The target lesion location determines incision placement during thoracotomy. Upper and middle lesions require a muscle-sparing vertical axillary incision along the midaxilla beginning along the lower border of the hairline ( Fig. 6-1 , line A). The incision is placed along the midaxillary line beginning inferior to the hairline. The serratus anterior muscle fibers overlying the third rib are divided along the rib long axis. The pectoralis minor is mobilized along the lateral edge and reflected medially. The third rib is resected subperiosteally and the posterolateral aspect of the fourth rib is bivalved. The chest is entered through the third interspace.
Figure 6-1
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Lower lobe lesions are approached by placing the incision along the posterior axillary line beginning approximately 3 to 4 cm below the axilla, just anterior to the medial edge of the latissimus dorsi muscle (see Fig. 6-1 , line B). The latissimus is reflected posteriorly, and the fatty avascular plane along the medial edge of the serratus anterior muscle is identified. The serratus is divided along the inferior margin of the wound in a radial fashion. The chest is entered through the fourth interspace. Transverse incision can also be used.
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Incision placement for thoracoscopic sublobar resection requires three port sites and one utility incision ( Fig. 6-2 ). The camera port (B) is placed in the midclavicular line at the sixth or seventh interspace. A retraction port (D) is inserted along the posterior clavicular line, fourth interspace. Stapler passage through this port avoids excessive torque during vascular division. A vertical dissection port (C) is made in the midclavicular line, second interspace. The 3- to 4-cm utility incision (A) is made along the anterior axillary line fourth interspace. The vertical dissection port or utility incision may be extended to convert to a vertical axillary thoracotomy or lateral thoracotomy, respectively. Exposure can be improved by partial rib removal. Proper stapler application is facilitated by making a 1.5-cm “accessory” port-site incision through the sixth interspace along the posterior axillary line.
Figure 6-2
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With the exception of superior segmentectomy, the dissection commences along the anterior hilum. We favor stapling for fissure dissection over cautery or blunt dissection along a poorly developed fissure to minimize intraoperative hemorrhage and postoperative air leak. Bronchovascular dissection and division are facilitated by 0-silk placement around the structures and retraction to facilitate stapler application.
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The apical and posterior segments of the right upper lobe may be resected singly or together. The apical segmental vein is divided in the anterior hilum, exposing the upper lobe branch of the right pulmonary artery. The anterior segmental artery is spared along the truncus anterior as the apical segmental branch is divided. The apical segmental bronchus can be divided by a posterior hilar dissection ( Fig. 6-3 ).
