Pulmonary sequestration is a congenital syndrome characterized by abnormal systemic blood supply to the lung, usually the lower lobe. The anomaly causes a predisposition for pulmonary complications such as infection and hemoptysis. There are two types of sequestrations, intralobar and extralobar. As the name implies, the intralobar sequestration is located within the lung (Fig. 82-1), whereas the extralobar sequestration is separate from the lung, enclosed in its own pleural envelope (Fig. 82-2). One should be aware of the various other associated anomalies, such as abnormal communication of the bronchial tree, systemic venous drainage, rare communication to the foregut, and diaphragmatic hernia (Table 82-1). In addition, the aberrant systemic vessel can arise from any systemic intrathoracic or upper abdominal vessel, such as the aorta, the subclavian artery, and even the coronary arteries. While they are found most commonly in the lower lobes, left more often than right, sequestrations also can occur in the right or left upper lobe.

Abbreviations: ELS is extralobar pulmonary sequestration; ILS is intralobar pulmonary sequestration.

Ferguson TB Jr, Ferguson TB. Congenital lesions of the lung and emphysema. In Sabiston DC Jr., Spencer FC (eds), Gibbon's Surgery of the Chest, 5th ed., Ch. 24. New York: Mosby, 1995:822–884.

CLINICAL PRESENTATION

Extralobar pulmonary sequestrations tend to present at an early age with respiratory distress because they are associated with other congenital anomalies, such as diaphragmatic hernias. They have systemic venous drainage and no bronchial communication. In contrast, intralobar sequestrations are commonly diagnosed in adulthood, present with frequent pulmonary infections or hemoptysis, have pulmonary venous drainage and a normal bronchial communication, and are rarely associated with other anomalies.^1–3 Fever, cough, multiple pulmonary infections, and hemoptysis can occur. The affected lobe tends to develop chronic changes owing to recurrent infections with eventual cystic destruction of the parenchyma. A chest x-ray that reveals consolidation along the medial aspect of the lower lobe should arouse suspicion of a sequestration. A chest CT scan can confirm the diagnosis of the sequestration, and angiography is not necessary. The treatment of choice for sequestration is resection. There are occasional reports of embolization with coils, but the durability and long-term sequelae of embolization remain unknown.⁴

IDEAL PATIENT CHARACTERISTICS AND PREOPERATIVE ASSESSMENT

Patients with sequestration who present in adulthood to thoracic surgeons are young with few comorbidities or associated anomalies. Pulmonary function is more than adequate to tolerate resection with lobectomy. CT scan or CT angiography are sufficient, and traditional catheterization and angiography are not required. If there is any suggestion of communication with the foregut, esophagogastroduodenoscopy may be needed as well. With the exception of severe hemoptysis, there is no need to operate on presentation. One can wait until the last bout of pneumonia and inflammation has subsided for several weeks to facilitate dissection and limit postoperative empyema.

TECHNIQUE

The operation involves resection of the sequestered aberrant vessel and affected lung parenchyma. The procedure can be performed by using video-assisted thoracic surgery or thoracotomy-type incisions.^1,5,6 Since it is important to resect all the affected and destroyed lung tissue, a lobectomy is often required in patients with intralobar sequestration.^1,3 The aberrant vessel should be resected and controlled at its origin (Fig. 82-3). Careful dissection will reveal several more centimeters of the vessel than is readily apparent on initial inspection. Since the venous return also may be anomalous, attention should be paid during dissection to avoiding inadvertent injury and uncontrolled bleeding. Communication to the foregut also can exist, and care should be taken to avoid leaving an open viscus unattended. Finally, the destroyed parenchyma has to be resected completely to avoid a nidus of infection and hemoptysis. Flap buttress of the bronchus may be considered to avoid bronchial dehiscence in patients with extensive inflammation.

POSTOPERATIVE CARE

Postoperative care in these patients is similar to that in other lobectomy patients, with the exception that blood pressure should be controlled in a narrower range because a blood vessel off the aorta has been divided.

PROCEDURE-SPECIFIC COMPLICATIONS

All the usual complications of performing a lobectomy for benign inflammatory lesions can occur. In addition, procedure-specific complications include bleeding from the aberrant vessels either intraoperatively from lack of control during division or from inadvertent injury when dissecting the vessel. Postoperative bleeding from the vessel can occur if the vessel is not divided appropriately or if the blood pressure is not controlled within an appropriate range. A long arterial stump can result in thrombus formation and paradoxical embolization. In addition, since this vessel is abnormal (i.e., histologically, it is more similar to a pulmonary artery than a systemic artery), it is predisposed to atheromatous and aneurysmal changes.⁷ Complete resection is warranted to avoid future complications. Empyema with or without bronchopleural fistula can occur when one operates for benign infectious disease. Operating under elective circumstances when there is no active infection ensures a lower incidence of these complications.

SUMMARY

Sequestration is a rare congenital abnormality of the systemic blood supply to part of the lung. In adults, the condition is heralded by recurrent infections and/or hemoptysis. Treatment involves resection of the aberrant vessel and affected lung parenchyma, preferably under elective circumstances. Preoperative identification of the aberrant vessel and of any associated abnormalities assists in the planning of the operation and prevention of complications.

CASE HISTORY

A 47-year-old woman underwent a CT scan as workup for back pain and was found to have a sequestration to the right lower lobe. The aberrant vessel originated in the descending thoracic aorta and had become aneurysmal. The patient had a CT angiogram to better define the vessel (Fig. 82-4). At thoracotomy, she was found to have an intralobar sequestration with an aneurysm of the aberrant vessel (Fig. 82-5). A right lower lobectomy was done with division of the aberrant vessel at its origin from the aorta with an endovascular GIA stapler.

EDITOR'S COMMENT

Dr. Zellos has expertly described the approach to identifying and treating sequestration. The key points to remember are first to identify and control the systemic artery and second to spare as much lung as possible, whenever it is possible to do so. We now generally approach these lesions thoracoscopically, and as a consequence, the patient experiences a much easier postoperative course.

–MJK

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