Anomalous systemic arterial supply to the normal

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1 Anomalous Systemic Arterial Supply to Normal Basal Segments of the Left Lower Lobe Akira Yamanaka, D, Takashi Hirai, D, Toshio ujimoto, D, itsuo Hase, D, asato Noguchi, D, and umio Konishi, D Departments of Chest Surgery, Respiratory Diseases, Radiology, and Pathology, ukui Red Cross Hospital, ukui, Japan Background. Anomalous arterial supply to the normal basal segments of the lower lobe without sequestration is a rare congenital abnormality, and whether it belongs to the broad spectrum of sequestration disorders remains controversial. ethods. The cases of all 4 patients who were treated surgically by us were reviewed together with 8 previously reported cases. Results. The anomalous artery originated from the descending thoracic aorta, distributed to the basal segments of the left lower lobe, and drained to a normal inferior pulmonary vein in each case. The anomalous artery was thick and elastic walled. rom the review of all 12 cases, male gender, left side, descending thoracic aorta as the aberrant arterial origin, absence of pulmonary blood flow to the basal segments, and normal pulmonary venous drainage were predominant. Despite some differences, the findings seemed closely related to intralobar sequestration. Surgical treatments were lung resection, anastomosis, and ligation of the anomalous artery. Conclusions. This anomaly is probably one type of sequestration complex. Both aortic and pulmonary arterial angiographic studies are needed to plan the definitive surgical procedure. (Ann Thorac Surg 1999;68:332 8) 1999 by The Society of Thoracic Surgeons Anomalous systemic arterial supply to the normal basal segments with normal bronchial connection of the lower lobe, which has no normal pulmonary arterial supply without sequestration, is a rare congenital anomaly. It was previously classified as one type of sequestration according to Pryce s terminology, but some synonyms have also been used. Whether the term sequestration is appropriate or not is controversial because of normal bronchial connections. This report describes our experience with various surgical treatments for anomalous arterial supply to the normal basal segments of the left lower lobe and reviews the other cases previously reported to date. Patients and ethods Patient 1 A 29-year-old man was referred to our hospital because of hemoptysis. Chest roentgenogram and computed tomography (CT) showed a retrocardiac nodular shadow. Preoperative bronchoscopy showed normal findings. Transbronchial biopsy could not provide a diagnosis of the lesion. The size of the nodule was unchanged despite the administration of antituberculous agents. Exploratory thoracotomy was performed to rule out lung cancer. A large systemic artery arising from the descending thoracic aorta supplied the basal segments of the lower lobe of the left lung. The pulmonary arteries to the basal Accepted for publication eb 23, Address reprint requests to Dr Yamanaka, Department of Chest Surgery, ukui Red Cross Hospital, Tsukimi, ukui , Japan; akiray@mitene.or.jp. segments were lacking. The aberrant artery was ligated, and left lower lobectomy was performed. A roentgenogram of the resected lower lobe with injection of contrast medium into the aberrant vessel showed the angiogram of the entire basal segment distribution without fistulae or connections with other vessels (ig 1A). Patient 2 A 30-year-old asymptomatic man was referred to our hospital for evaluation of an abnormal shadow on a chest roentgenogram film. Chest roentgenogram and CT revealed a retrocardiac nodular shadow. agnetic resonance imaging (RI) of the chest revealed a partial defect of the descending thoracic aortic wall and the orifice of the abnormal vessel branching. Aortography showed an anomalous artery from the descending thoracic aorta entering the basal segments of the left lower lobe (ig 1B). Pulmonary arteriography showed a complete lack of pulmonary arterial supply to the basal segments. Preoperative bronchoscopy showed normal findings. The anomalous vessel was transected at its origin, and the proximal end was oversewn with 3-0 polypropylene. Behind the bronchus and the superior segment of the lower lobe, end-to-side anastomosis between the anomalous artery and the inferior side of the pulmonary artery was performed with 5-0 polypropylene without resection of the basal segments. A small section of the lung (S8) was removed for histologic examination. Anticoagulation and antiplatelet therapy were continued. After 6 months, although pulmonary angiography showed that the flow into the lower lobe of the left lung had improved, and a lung perfusion scan revealed little 1999 by The Society of Thoracic Surgeons /99/$20.00 Published by Elsevier Science Inc PII S (99)

2 Ann Thorac Surg YAANAKA ET AL 1999;68:332 8 ANOALOUS SUPPLY TO THE LUNG 333 Patient 3 A 46-year-old man was referred to our hospital because of cough and sputum, with a history of hemoptysis. Chest roentgenogram and CT showed a retrocardiac shadow in the left lower lung field. Chest RI revealed an abnormal vessel from the descending thoracic aorta. Pulmonary arteriograms and aortograms revealed a normal pulmonary arterial supply to the superior segment of the left lower lobe and a large artery arising from the descending thoracic aorta supplying the basal segments of the left lower lobe. There were no pulmonary arteries to the basal segments. Preoperative bronchoscopy showed normal findings. The aberrant artery was ligated, and left lower lobectomy was performed. Patient 4 A 68-year-old woman was referred to our hospital because of exertional dyspnea with a history of hemoptysis. Chest roentgenogram film showed a retrocardiac shadow, and chest CT was suggestive of an anomalous systemic arterial supply to the left lower lobe. Chest RI revealed a partial defect of the descending aortic wall. The pulmonary arteriograms and the aortograms revealed a normal pulmonary arterial supply to the superior segment of the left lower lobe and a large artery arising from the descending thoracic aorta supplying the basal segments of the left lower lobe. There were no pulmonary arteries to the basal segments. Preoperative bronchoscopy showed normal findings. As the interlobar lobulation was incomplete, and basalectomy of the left lower lobe with ligation of the aberrant artery was performed. Results Case Summaries The clinical features of the 4 patients are summarized in Table 1. ig 1. Angiography of the anomalous arteries: (A) patient 1, (B) patient 2. In patient 1, the anomalous artery in the resected lobe is injected with barium sulfate. In patient 2, preoperative angiogram is demonstrated. Anomalous artery distributes into all basal segments. improvement in that value. ive years after surgery, the patient had no respiratory symptoms. Arterial blood gas analysis revealed no evidence of right-to-left shunt. CLINICAL ANIESTATIONS. Three were adult men and one was an elderly woman. No patient complained of either severe symptoms or history of respiratory infections. Patients 1, 3, and 4 were admitted with clinical symptoms, while patient 2 had no respiratory symptoms. Although the final diagnosis was made during a surgical operation in patient 1, a preoperative diagnosis was achieved in the 3 other patients. Cardiac murmurs or abnormal electrocardiogram (ECG) findings were not detected in any of the patients. In blood studies, no inflammatory findings were demonstrated. Bronchoscopy, which was performed in each patient, showed all major bronchi of the left lung to be in their normal location. ROENTGENOLOGICAL INDINGS AND ANGIOGRAPHY. In the first case, an angiogram of the resected specimen seemed to show the same findings as the other three cases. The contrast medium filled the capillaries without leakage into other vessels (ig 1A). In the other 3 cases, a preoperative angiogram showed that the left basal seg-

3 334 YAANAKA ET AL Ann Thorac Surg ANOALOUS SUPPLY TO THE LUNG 1999;68:332 8 Table 1. Clinical eatures of the Patients Variable Patient 1 Patient 2 Patient 3 Patient 4 Age (y), gender 29, male 30, male 46, male 68, female Symptom hemoptysis asymptomatic cough, sputum dyspnea, hemopytsis Supply descending thoracic aorta Side, location left pulmonary ligament Distribution left basal segments No. of arteries Diameter (origin, maximum, mm) 7, 30 8, 9 15, 20 5, 20 Pulmonary artery no pulmonary arteries to the basal segments branching Drainage normal inferior pulmonary venous drainage into the left atrium Aortic arch normal left aortic arch Intrathoracic anomaly none Surgery lower lobectomy anastomosis a lower lobectomy basalectomy a End-to-side anastomosis between the anomalous artery and the inferior side of the pulmonary artery. ments were supplied by one anomalous artery arising from the descending thoracic aorta without pulmonary blood flow. The anomalous artery was smaller in diameter, running caudally at its origin, tortuous until it ran cranially to the proximal lower lobe like a swan neck-shaped curve, and then it was dilated aneurysmatically running along with a normal pulmonary artery into all the basal segments. There was a normal pulmonary capillary phase, and normal inferior pulmonary venous drainage into the left atrium, thereby excluding a direct fistula between the aberrant systemic artery and the pulmonary veins (ig 1B). Chest CT was performed in each patient. As a general feature, it showed a lobulated or branching nodular shadow with many tangentially cut vessels around it (ig 2). Chest RI was performed in 3 patients, excluding the first, and showed a defect of the aortic wall at the branching orifice of the aberrant artery (ig 3). OPERATIVE INDINGS AND SURGICAL PROCEDURE. The chest was opened by a posterolateral incision. At thoracotomy, intrapleural findings included normal left aortic arch without pleural adhesion, lung hypoplasia, or diaphragmatic hernia. The visceral pleura of the basal segments of the lower lobe was covered with many telangiectases and anthoracoses, and the lower lobe ventilated well with no masses. At its origin, the anomalous artery was smaller in diameter (mean 9 mm in diameter) in the pulmonary ligament, but just beyond this site entering the lobe, it dilated aneurysmatically (mean 20 mm in diameter). The left inferior pulmonary vein was normal in size. There was no degenerate connection between the anomalous artery and pulmonary artery. Left lower lobectomy with ligation of the anomalous artery was performed in patients 1 and 3, left basalectomy with ligation of the anomalous artery in patient 4, and anastomosis between the anomalous artery and pulmonary artery without resection of the basal segments in patient 2. The postoperative course was uneventful and resulted in clinical improvement in each patient. ig 2. Chest CT: patient 2 (top), patient 4 (bottom). In patient 2, the lobulated nodular shadow is demonstrated at the proximal lower lobe. In patient 4, the nodular vascular shadow with tangentially cut vessels around itself is observed.

4 Ann Thorac Surg YAANAKA ET AL 1999;68:332 8 ANOALOUS SUPPLY TO THE LUNG 335 Review of the Literature Previously reported cases in the English literature including the present 4 cases are summarized in Table 2. The cases of systemic artery-pulmonary vein fistula or those with an inflammatory mass in the resected specimen were excluded. Age distribution was from 0 months to 68 years, below 6 years in 6 and over 20 years in 6, with an average age of 21.2 years. ale gender, left side, and descending thoracic aorta as the aberrant arterial origin were predominant. In all cases, the number of anomalous arteries was one. The perfusion area of the anomalous artery was the basal segments of the lower lobe with normal pulmonary venous drainage into the left atrium. In one of the right-sided cases, the aberrant artery arose from the celiac axis. Surgical procedures were lobectomy in 9 cases, basalectomy in 1, and anastomosis between the anomalous artery and pulmonary artery in 2. ig 3. Chest RI: patient 3 (top), patient 4 (bottom). A defect of the aortic wall (arrow) at the branching point of the anomalous artery is observed. HISTOPATHOLOGICAL INDINGS. Resected specimens were obtained from all patients. Histopathological examination showed that the anomalous arteries were tortuous, thick walled, and elastic, and had atherosclerotic change. There was fibrosis, scattered hemosiderin-laden macrophages in the lung parenchyma, and a thrombus in a peripheral artery in each case. In the peripheral area, airway and artery with a thick elastic wall in the bronchoarterial bundle were shown. In the small bundle, the pulmonary artery was narrower or showed obstructive change. There was no evidence of bronchiectasis, chronic infection, sequestration, or dysplastic change. Comment Anomalous systemic arterial supply to normal segments of the lung is a rare congenital anomaly. This disease has been classified as Pryce type I sequestration [1]. Recently, some synonyms: systemic arterial supply to (the basal segments of) the lung, etc. [2 6], systemic origin of the sole artery to the basal segments of the lung [7], or systemic arterialization of lung without sequestration [8, 9], have also been used for this condition. Despite this nomenclature, Sade and associates [10] introduced the concept of a sequestration spectrum for the classification of various complexes of bronchovascular anomalies. The concept that this anomaly is one of the subtypes of this spectrum was reviewed by Thilenius and associates [11]. But whether the term sequestration is appropriate remains controversial. As a similar spectrum concept, Clements and Warner [12] presented pulmonary malinosculation spectrum. Pulmonary sequestration is defined as a mass of abnormal pulmonary tissue that does not communicate with the tracheobronchial tree through a normally located bronchus and that is supplied by an anomalous systemic artery [10]. According to this definition, the anomaly we are reviewing cannot be considered a type of true pulmonary sequestration, because the lesion of bronchopulmonary and parenchymal tissue of this disease is never sequestered. urthermore, if any pulmonary lesion with systemic arterial supply is included in the sequestration, it seems questionable whether the lung is sequestered in the patients with combined supply from the normal pulmonary artery and anomalous systemic artery to normal lung parenchyma [6, 9, 13], as shown in Table 3, or in patients with a systemic arterypulmonary vein fistula. Despite these differences, systemic arterial supply to normal lung is probably closely related to pulmonary sequestration. The location of this disease is the lower lobe, especially in the basal segments, as is true of most cases of pulmonary sequestration. The characteristics of these aberrant arteries, whose origin is in the pulmonary ligament or below the diaphragm and that have histologically an elastic-type (so-called pulmonary type) arterial wall, are the same as in pulmonary sequestration. Several investigators [1, 7, 12, 14] have indicated that the aberrant arteries in this disease as well as in pulmonary sequestration are distinct from bronchial arteries. The venous

5 336 YAANAKA ET AL Ann Thorac Surg ANOALOUS SUPPLY TO THE LUNG 1999;68:332 8 Table 2. Review of the Literature Published in English to Date Including Present Cases of Anomalous Systemic Arterial Supply to the Normal Basal Segments of the Lower Lobe Reference Year Age, Gender Clinical anifestations Side Origin No. of Arteries Arterial Perfusion to Lower Lobe PA Perfusion to Lower Lobe Drainage Surgery 1. Hessel [7] y, 2. Litwin mo, [20] 3. Kirks y, [2] 4. Kirks mo, [2] 5. Ishihara y, [4] 6. Yabek mo, [3] 7. lisak y, [8] 8. Tao [5] y, 9. Present y, 10. Present y, 11. Present y, 12. Present y, heart murmur L DTA 1 basal segments S6 IPV anastomosis heart murmur, R DTA 1 basal segments S6 IPV a lobectomy respiratory distress heart murmur L DTA 1 basal segments S6 IPV lobectomy heart murmur L DTA 1 basal segments S6 IPV lobectomy heart murmur L DTA 1 basal segments S6 IPV a lobectomy heart murmur, L DTA 1 basal segments S6 IPV lobectomy respiratory distress dyspnea, hemoptysis R celiac 1 basal segments a S6 IPV a lobectomy axis dyspnea L DTA 1 basal segments S6 IPV lobectomy hemoptysis L DTA 1 basal segments S6 IPV lobectomy abnormal shadow L DTA 1 basal segments S6 IPV anastomosis cough, sputum L DTA 1 basal segments S6 IPV lobectomy dyspnea, hemoptysis L DTA 1 basal segments S6 IPV basalectomy Limited listing of the cases in which the anomalous artery is the sole arterial supply to the involved segments. a Description is not clear. DTA descending thoracic aorta; IPV inferior pulmonary vein; L left; PA pulmonary artery; R right. drainage is the pulmonary vein, which is consistent with intralobar sequestration rather than extralobar type. In some reported cases of pulmonary sequestration, a normal communication with a normal bronchial tree was evident without inflammatory change [15]. These findings suggest the difficulty in considering this anomaly as a completely independent disease from pulmonary sequestration. rom the standpoint of embryology, bronchial growth is dependent not only on the available celomic space [16], but also on pulmonary arteries, which provide the primary blood supply to developing lung tissue [1], with bronchial blood supply alone insufficient to supply the nutritional needs of the growing fetal lung [16]. As regards lung development, we cannot separate the relations between the bronchial bud and adjacent artery. If we define the term sequestration as a congenital nonfunctioning pulmonary lesion mainly supplied by an anomalous systemic artery, anomalous arte- Table 3. Review of the Literature Published in English to Date of Anomalous Systemic Arterial Supply to Normal Lower Lobe of the Lung Reference Year Age, Gender Clinical anifestations Side Origin No. of Arteries Arterial Perfusion to Lower Lobe PA Perfusion to Lower Lobe Drainage Surgery 1. Campbell [6] y, 2. Campbell mo, [6] 3. Painter [9] y, 4. Ernst [13] y, abnormal shadow R Abd A 2 basal segments N SPV lobectomy heart murmur L DTA 1 basal segments a N IPV ligation hemoptysis R celiac 1 basal segments a N IPV segmentectomy axis heart murmur R Abd A 1 basal segments N IPV a ligation Limited listing of the cases in which the normal pulmonary artery is also the arterial supply to the involved segments. a Description is not clear. Abd A abdominal aorta; DTA descending thoracic aorta; IPV inferior pulmonary vein; L left; N normal; PA pulmonary artery; R right; SPV superior pulmonary vein.

6 Ann Thorac Surg YAANAKA ET AL 1999;68:332 8 ANOALOUS SUPPLY TO THE LUNG 337 rial supply to normal lung may be included in the wide spectrum of pulmonary sequestration. It would be named arterial sequestration, whereas classical pulmonary sequestration would be named broncho-arterial sequestration, as Thilenius and associates [11] previously suggested. The embryology of the lung and its relationship to this anomaly have been summarized by several authors. At about 28 days of embryonic life (main bronchi appear, when the embryo is 4.6 mm long) [17, 18], the lung bud is supplied by systemic capillaries, the splanchnic plexus [8, 10] or primitive bronchial arteries [8, 17], which have numerous connections with the primitive dorsal aorta [8, 10, 12, 17] in the neck near the celiac axis [17]. At the 5th week (lobar bronchi appearance, 8.5 mm) [17, 18], from the caudally directed ventral sprouts of the sixth aortic arch, plexiform vessels (pulmonary arteries) appear and grow toward the lung bud [16, 17]. The ventral and dorsal sixth branch is connected and forms the sixth arch. At the 6th week (segmental bronchi appearance) [17], the splanchnic supply normally regresses once the pulmonary arterial system becomes established [8, 12, 17]. Pulmonary oligemia [8] or other events are factors with either persistence or reestablishment of pulmonarysplanchnic collaterals. The most likely theory is that if the early branches arising from the aorta persist, this causes one type of anomalous systemic supply to the lung [2, 7, 16, 17]. The case with combined supply from the pulmonary artery and systemic artery to normal lung parenchyma might also support this theory. As far as definitive bronchial arteries are concerned, they develop between the 9th and 12th week and communicate with the capillary bed in the airway walls [16, 17]. In all our cases, the anomalous systemic artery arose from the descending thoracic aorta and supplied solely the left normal basal segments with normal pulmonary venous drainage into the left atrium without associated normal pulmonary arterial supply to the involved segments. Although the majority of the reported cases exhibit almost the same pattern as our cases [2 5, 7], other cases in which the anomalous artery supplies the right lower lobe or arises from the celiac axis also exist. As shown in Table 3, some reported cases had a normal pulmonary arterial supply in addition to anomalous systemic arterial supply to the involved segments [6, 9, 13]. Of these 4 cases, the anomalous systemic artery arose from the descending thoracic aorta in 1 [6], and from the abdominal aorta (or the celiac axis) in 3 [6, 9, 13]. They should also be included in the wide spectrum of pulmonary sequestration as an incomplete type of anomalous systemic arterial supply to normal lung. As a general trend, anomalous artery arising from the descending thoracic aorta supplied the left lower lobe, while the one arising from the abdominal aorta (or the celiac axis) supplied the right lower lobe with normal pulmonary arterial branches as well. As regards the morphological findings, the anomalous artery was smaller in diameter at its origin in the pulmonary ligament, but dilated just beyond this site entering the lobe, especially in the left-sided cases. It was also observed that the surface of the affected segments was covered with many telangiectases. Although most of the patients are asymptomatic, the main clinical symptoms of this disease are hemoptysis [8, 9] and exertional dyspnea [3, 5, 8]. Asymptomatic patients were referred because of abnormal shadow or cardiac murmur. Physical examination revealed heart murmurs over the precordium and the lower posterior thorax in children [4], but not in the older patients. Heart murmurs were continuous murmurs simulating a patent ductus arteriosus [2, 3, 7] or systolic murmurs [2, 4]. Occasionally, the shunt, when sufficiently large, produced leftsided cardiac overload and congestive heart failure [3]. In pediatric patients, ECG was used to show left ventricular hypertrophy. The diagnosis should be suspected in the presence of a continuous murmur or unilateral increase in pulmonary blood flow in pediatric patients. In older patients, roentgenological findings are more important than physical examinations. CT is useful for the diagnosis and showed a retrocardiac nodular (vascular) shadow connected to the descending aorta branching into the basal segments of the relatively normal lower lobe [5, 19]. CT was performed in all our 4 cases. Although our first patient was misdiagnosed, a preoperative diagnosis was achieved by CT in the other 3 patients. It shows a retrocardiac nodular shadow that lobulates and runs circumferentially, and demonstrates a nearly normal bronchial tree and normal pulmonary parenchyma without mass or cystic change. Bronchoscopy confirms the normal major bronchial branchings. Provided this anomaly is kept in mind, the diagnosis is not difficult. The usefulness of RI has also been described in a few reports. In our experience, RI, which was performed in 3 patients, was also useful for showing the abnormal vessel branching from the descending thoracic aorta or a partial defect of the descending aortic wall at the abnormal vessel branching point. Needless to say, angiography is the most useful method to establish the exact diagnosis. To accurately delineate the vascular anatomy and to plan definitive surgical therapy, both aortic and pulmonary arterial angiographic studies are needed. Before deciding the operative procedure, it is necessary to know whether normal pulmonary arteries branch to the involved lung, or whether the aberrant artery provides the blood flow to the entire involved lung with capillary phase, or demonstrates direct drainage of the blood flow into the pulmonary vein. Surgery is indicated for all patients with this anomaly because it is associated with potential risks, such as hemopytsis due to pulmonary hypertension and heart failure due to left-to-left shunt [3]. In most reported cases of this disease, lobectomy was performed. Other operative procedures include segmentectomy, anastomosis between the anomalous artery and pulmonary artery, or ligation of the anomalous artery. In our 4th case, who was probably the oldest patient reported in the literature, basalectomy was performed because of the incompleteness of interlobar lobulation. Hessel and associates [7] first reported successful anastomosis in a 5-year-old boy,

7 338 YAANAKA ET AL Ann Thorac Surg ANOALOUS SUPPLY TO THE LUNG 1999;68:332 8 and described pulmonary artery angiography, which revealed normal flow with no evidence of right-to-left shunt into the lower lobe of the left lung after surgery. This surgical method might be feasible for a pediatric patient in whom the involved segments of pulmonary parenchyma are normal and the anomalous vessel functions physiologically as a pulmonary artery. In our 2nd patient, as he had no airway symptoms, the anastomosis was performed as we previously reported [19]. Although dyspnea on effort improved due to disappearance of the left-to-left shunt, a lung perfusion scan revealed little improvement postoperatively. In such an adult patient, this procedure would likely be inefficacious in preserving the normal lung circulation because of already established atherosclerotic change and obstruction with thrombus of the anomalous artery. The last procedure, ligation of the anomalous arteries only, can be indicated for patients whose lung tissue has normal pulmonary artery branches [6, 13] in addition to those with systemic artery-pulmonary vein fistula. References 1. Pryce D. Lower accessory pulmonary artery with intralobar sequestration of lung: a report of seven cases. J Pathol 1946;58: Kirks DR, Kane PE, ree EA, Taybi H. Systemic arterial supply to normal basilar segments of the left lower lobe. Am J Radiol 1976;126: Yabek S, Burstein J, Berman W Jr, Dillon T. Aberrant systemic arterial supply to the left lung with congestive heart failure. Chest 1981;80: Ishihara Y, ukuda R, Awaya Y, et al. Anomalous systemic arterial supply to the basal segments of the lung presenting with a murmur. Eur J Pediatr 1979;131: Tao CW, Chen CH, Yuen KH, Huang H, Li WY, Perng RP. Anomalous systemic arterial supply to normal basilar segments of the lower lobe of the left lung. Chest 1992;102: Campbell DC Jr, urney JA, Dominy DE. Systemic arterial blood supply to a normal lung. J Am ed Assoc 1962;182: Hessel EA II, Boyden EA, Stamm SJ, Sauvage LR. High systemic origin of the sole artery to the basal segments of the left lung: findings, surgical treatment, and embryologic interpretation. Surgery 1970;67: lisak E, Chandrasekar AJ, arsan RE, Ali. Systemic arterialization of lung without sequestration. Am J Radiol 1982;138: Painter RL, Billig D, Epstein I. Anomalous systemic arterialization of the lung without sequestration. N Engl J ed 1968;279: Sade R, Clouse, Ellis H Jr. The spectrum of pulmonary sequestration. Ann Thorac Surg 1974;18: Thilenius OG, Ruschhaupt DG, Replogle RL, Bharati S, Herman T, Arcilla RA. Spectrum of pulmonary sequestration: association with anomalous pulmonary venous drainage in infants. Ped Cardiol 1983;4: Clements BS, Warner JO. Pulmonary sequestration and related congenital bronchopulmonary-vascular malformations: nomenclature and classification based on anatomical and embryological considerations. Thorax 1987;42: Ernst SPG, Bruschke AVG. An aberrant systemic artery to the right lung with normal pulmonary tissue. Chest 1971;60: Savic B, Birtel J, Tholen W, unke HD, Knoche R. Lung sequestration: report of seven cases and review of 540 published cases. Thorax 1979;34: Takahashi, Ohno, ihara K, atsuura K, Sumiyoshi A. Intralobar pulmonary sequestration. Radiology 1975;114: Hasleton PS. Embryology and development of the lung. In: Hasleton PS, ed. Spencer s pathology of the lung. 5th ed. New York: cgraw-hill, 1996: Deello D, Reid L. Arteries and veins. In: Crystal RG, West JB, Barnes PJ, Cherniack NS, Weibel ER, eds. The lung: scientific foundations. New York: Raven Press, 1991: raser RG, Paré JAP, Paré PD, raser RS, Genereux GP. The normal chest: Development and growth of the lung. In: raser RG, Paré JAP, Paré PD, raser RS, Genereux GP, eds. Diagnosis of diseases of the chest. 3rd ed. Philadelphia: WB Saunders, 1988: Hirai T, Ohtake Y, utoh S, Noguchi, Yamanaka A. Anomalous systemic arterial supply to normal basal segments of the left lower lobe. Chest 1996;109: Litwin SB, Plauth WH Jr, Nadas AS. Anomalous systemic arterial supply to the lung causing pulmonary-artery hypertension. N Engl J ed 1970;283: