Asian Cardiovasc Thorac Ann 2006;14:3-6
© 2006 Asia Publishing EXchange Ltd
Pulmonary Sequestration and Surgical Treatment
Onur Genç, MD,
Sedat Gürkök, MD,
Mehmet Dakak, MD,
Alper Gözübüyük, MD,
Murat Özkan, MD,
Hasan Çaylak, MD
Department of Thoracic Surgery, Gülhane Military Medical Academy, Ankara, Turkey
For reprint information contact: Sedat Gürkök, MD Tel: 90 312 304 5172 Fax: 90 312 304 2900 Email: sgurkok{at}gata.edu.tr, Department of Thoracic Surgery, Gülhane Military Medical Academy, Etlik, Ankara 06018, Turkey.
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ABSTRACT
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Pulmonary sequestration is nonfunctioning, abnormal pulmonary tissue existing inside or outside the visceral pleura. It is not connected to the tracheobronchial tree. In this study, the results of 8 patients, who were diagnosed with pulmonary sequestration and treated during hospitalization in Gülhane Military Medical Academy between 1996 and 2003, were reported. Sex, age, symptoms, diagnostic approach, operative findings, procedures and postoperative outcomes were reviewed. No postoperative complications were seen. In the long-term follow-up all patients were seen to be asymptomatic. We believe surgical resection is mandatory in order to avoid infection and destruction of the normal pulmonary parenchyma even in asymptomatic cases. Furthermore, when infection occurs, major resection such as lobectomy may be necessary rather than segmentectomy or wedge resection, which involves removal of minimal pulmonary parenchyma.
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INTRODUCTION
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Pulmonary sequestration (PS) is abnormal pulmonary tissue, having no function, existing inside or outside the visceral pleura. It is not connected to the tracheobronchial tree. Arterial supply and venous drainage can be either systemic or pulmonary. Bronchopulmonary sequestration is classified as either extralobar (ELS) or intralobar (ILS). ELS is separated from normal lung tissue by its own visceral pleura whereas ILS is incorporated within normal lung tissue.1–2
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PATIENTS AND METHODS
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In this study, the results of 8 patients, who were diagnosed with pulmonary sequestration and treated during hospitalization in Gülhane Military Medical Academy between 1996 and 2003, were reported. Sex, age, symptoms, diagnostic approach, operative findings, procedures and postoperative outcomes were reviewed.
The age of the patients ranged between 20 and 26 years (median 22). All patients were male. Only 2 patients were diagnosed as having pulmonary sequestration by preoperative diagnostic procedures. For the other 6 patients, thoracotomy was performed as a result of lesions detected by chest radiography and thorax computerized tomography (CT), and diagnosed as pulmonary sequestration during intraoperative and postoperative procedures. Respiratory tract infection was detected in 5 symptomatic patients and several courses of medical treatment were administered. In the 3 asymptomatic patients, the lesion was revealed incidentally by chest radiography, during imaging investigations for other indications, and established as pulmonary sequestration.
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RESULTS
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Exploration by posterolateral thoracotomy was performed on 8 patients. In 5 of 8 patients intralobar sequestration was detected and in the rest extralobar sequestration was revealed. Excision was applied for extralobar sequestration. For patients having intralobar sequestration lobectomy was performed (Table 1
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The sequestrational segment was supported by the thoracic aorta in 5 patients, by the subclavian artery in 1 patient (Figure 1), by the abdominal aorta in 1 patient and by both the thoracic and abdominal aorta in 1 patient. Venous drainage was via the inferior pulmonary vein in 5 patients, the hemiazygos vein in 1 patient, both the left innominate and superior pulmonary vein in 1 patient and directly to the right atrium in 1 patient. The location of ELS in one patient was in the left hemithoracic duct and anterior mediastinum (Figure 2), and in variant locations shown in Figure 3 and 4. No postoperative complications were seen. In the long-term follow-up all patients were seen to be asymptomatic.
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DISCUSSION
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Pulmonary sequestration is a "bronchopulmonary-foregut malformation". Whilst numerous theories regarding its pathogenesis are suggested, a common pathogenesis explaining the various clinical presentations still does not exist. On histopathologic examination PS consists of a few alveoli and bronchial glands with cystic structures, which are irregularly located, in various sizes and covered by pulmonary tract epithelia. Cartilage can be seen in the walls of some of the cystic structures.2–3
ELS generally presents with no symptoms.4 In our series, only one case of ELS was symptomatic. ILS generally presents with signs of infection whilst 15% of patients are asymptomatic.4 However, in our series; the ILS sub-type of pulmonary sequestration presented as asymptomatic in 2 cases (40%). Recurrent pulmonary infections in the pediatric age group are suggestive of ILS.2 An increase in cardiac output attributed to left to left shunting in ILS may lead to cardiac failure. Left ventricular function may also be impaired due to continuous enlargement of the shunt. Thus, ILS can be masked as a cardiac malformation for years.5
Pulmonary sequestration is seen 4 – 6 times more in the left than the right system.3,6 In our 8 cases, only 2 of them had pulmonary sequestration in their right systems and the rest had left sided pulmonary sequestration. Pulmonary sequestration generally reveals as a single cyst having air-fluid level or multicystic lesions and sometimes as a noncystic mass on chest X-Ray.2–3 The most accurate diagnostic tool in pulmonary sequestration is selective angiography. It reveals the arterial supply and the venous drainage of the sequestration. It is also a useful method to preclude differential diagnoses such as indeterminate foreign bodies or tumor.2 Preoperative selective angiography was used in only 2 of our patients as a diagnostic method.
ILS is 6 times more common than ELS. Typically ILS is located on the posterobasal side in the inferior lobes and two thirds of them are located on the left side. Upper or middle lobe localizations are rarely seen.2 The ILS was localized on the left posterobasal side of the inferior lobe in 5 of our patients. ELS is generally seen on the posterior costophrenic angle, having a close relationship with the aorta or esophagus. However, it can be seen in any localization.6 Our cases of ELS were localized in the upper, middle, and superior regions of the hemithoracic duct.
Vertebra, chest wall, diaphragm and foregut abnormalities are seen more frequently with ELS. ELS also exists together with diaphragmatic hernia in 30 – 50% of cases.3 Congenital diaphragmatic hernia is more commonly seen in inferiorly located ELS cases.1 Typically, ELS reveals as a supradiaphragmatic asymptomatic mass on chest X-Ray.3 Arterial supply is from the systemic artery in 95% of cases and from the pulmonary artery in 5% of cases. Venous drainage is almost always to the systemic veins.7 Systemic arterial supply and venous drainage of ELS is supradiaphragmatic in 80–90% cases. An infradiaphragmatic vascular structure is more common when ELS is seen concurrently with diaphragmatic hernia.3 Arterial supply was from the thoracic aorta in two patients and from the subclavian artery in one patient in our series.
Pulmonary sequestration encounters 1 – 2% in whole pulmonary resections.2 Savic et al8 demonstrated in a study of 547 patients diagnosed with pulmonary sequestration, that arterial supply of ILS was via the thoracic aorta in 74% cases, the abdominal aorta in 18.7% cases and the intercostal artery in 3.2% cases. Generally, aberrant arteries, mostly single or sometimes multiple, originate from the descending aorta at the level of the diaphragm and course superiorly within the inferior pulmonary ligament to enter the sequestration. A subdiaphragmatic aberrant artery is more common in right-sided ILS. The diameter of the artery is generally between 0.5 and 2 cm. If the arterial diameter is smaller than 3 mm, it is more likely to be a component of a multiple system. Venous drainage is almost always via the inferior pulmonary vein.2 In our series, the arterial supply was from a branch of the thoracic aorta in 3 patients, from a branch of the abdominal aorta in 1 patient and from branches of both thoracic and abdominal aorta in 1 patient.
When the systemic artery that supplies the pulmonary sequestration is examined histologically, the structure resembles the pulmonary artery having grossly elastic components rather than muscular walls characteristic of systemic arteries.2,6
During surgery, the inferior pulmonary ligament should be carefully explored due to the risk of an aberrant artery existing within it.2 A staged bilateral thoracotomy is safer and technically easier than median sternotomy in cases of bilateral PS. This is based on the following considerations:
- Sequestration is generally seen in lower lobes,
- The abnormal artery is generally inside the pulmonary ligament and control of this area anteriorly is difficult,
- The abnormal artery generally arises from the aorta and control of the aorta anteriorly is difficult,
- The fragile elastic structure of the abnormal artery makes it susceptible to damage.6
In pulmonary sequestration bacterial transfer may occur during the air transfer between the normal pulmonary parenchyma and sequestration area, via microscopically seen connections, and bacterial infections may arise. The sequestration area is congenitally dysplastic and tumor developments have been reported.8 Morbidity and even mortality may occur as a result of massive hemorrhage.2
We believe resection is the optimal procedure in order to avoid infection and destruction of the normal pulmonary parenchyma even in asymptomatic cases. Furthermore, when infection occurs a major resection such as lobectomy may be necessary rather than segmentectomy or wedge resection, which involves removal of less pulmonary parenchyma.
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REFERENCES
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- Sade RM, Clouse M, Ellis FH Jr. The spectrum of pulmonary sequestration. Ann Thorac Surg 1974;18:644–58.[Medline]
- Gustafson RA, Murray GF, Warden HE, Hill RC, Rozar GE. Intralobar sequestration. A missed diagnosis. Ann Thorac Surg 1989;47:841–7.[Abstract]
- Canty TG. Extralobar pulmonary sequestration. Unusual presentation and systemic vascular communication in association with a right-sided diaphragmatic hernia. J Thorac Cardiovasc Surg 1981;81:96–9.[Abstract]
- Jeanfaivre T, AfiM, L’hoste P, Tuchais E. Simultaneous discovery of bilateral intralobar and extralobar pulmonary sequestrations. Ann Thorac Surg 1997;63:1171–3.[Abstract/Free Full Text]
- Fabre OH, Porte HL, Godart FR, Rey C, Wurtz AJ. Long-term cardiovascular consequences of undiagnosed intralobar pulmonary sequestration. Ann Thorac Surg 1998;65:1144–6.[Abstract/Free Full Text]
- Roe JP, Mack JW, Shirley JH. Bilateral pulmonary sequestrations. J Thorac Cardiovasc Surg 1980;80:8–10.[Abstract]
- Sippel JM, Ravichandran PS, Antonovic R, Holden WE. Extralobar pulmonary sequestration presenting as a mediastinal malignancy. Ann Thorac Surg 1997;63:1169–71.[Abstract/Free Full Text]
- Savic B, Birtel FJ, Tholen W, Funke HD, Knoche R. lung sequestration: report of seven cases and review of 540 published cases. Thorax 1979;34:96–101.[Abstract/Free Full Text]
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ABSTRACT
INTRODUCTION
