Repair of Scimitar Syndrome
2001; Elsevier BV; Volume: 6; Issue: 1 Linguagem: Inglês
10.1053/otct.2001.22698
ISSN1532-8627
AutoresGlenn J. Pelletier, Thomas L. Spray,
Tópico(s)Congenital Heart Disease Studies
ResumoScimitar syndrome is a complex constellation of vascular, bronchial, and parenchymal malformations of the right lung. This rare congenital malady was first described in autopsy specimens by Cooper1Cooper G Case of malformation of the thoracic viscera: Consisting of imperfect development of right lung, and transposition of the heart.London Med Gaz. 1836; 18: 600-601Google Scholar in London and Chassinat2Chassinat R Observation d'anomalies anatomiques remarquables de I'appareil circulatoire, avec hepatocele congeniale, n'ayant donne lieu pendant la vie a aucun symptom particulier.Arch gen de med de Paris, ser 2. 1836; 11: 80-81Google Scholar in Paris in 1836. The hallmark feature is anomalous venous drainage of the right lung that produces a distinctive image on anteroposterior chest roentgenogram (Fig 1) resembling a scimitar, a Turkish sword (Fig 2). It was Neill and associates3Neill CA Ferencz C Sabiston D et al.The familial occurrence of hypoplastic right lung with systemic arterial supply and venous drainage.Bull Johns Hopkins Hosp. 1960; 107: 1-15PubMed Google Scholar who recognized this resemblance in 1960 and coined the term “scimitar syndrome” to describe this set of anatomic aberrations.2A scimitar.View Large Image Figure ViewerDownload (PPT) Typically, the pulmonary (or “scimitar”) vein is single, drains the whole lung, courses parallel to the right heart border in a curvilinear path, and terminates in the inferior vena cava below the diaphragm. The classic radiographic appearance is present, in only about one-third of reported cases.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar In the remaining two-thirds of cases, the vein may be obscured by the right heart border or may be a size and shape that is less prominent radiographically. The vein may be multibranched, which reduces its radiographic density. The extent of right lung drainage by the anomalous vein also varies. Most typically, scimitar vein drains the entire right lung (Fig 3), but several variations have been reported. The right upper lobe may drain separately into the left atrium while the remainder of the pulmonary venous drainage enters the inferior vena cava. Alternatively, the anomalous vein may drain into the inferior vena cava directly and into the left atrium indirectly via a bridging vein. In another path, the right superior pulmonary vein enters either the right atrium or the superior vena cava and the remainder of the pulmonary venous blood travels to the inferior vena cava via the scimitar vein. There have even been reports of a vein with the typical scimitar appearance that drains the right lung normally into the left atrium. In all cases but the last, the left-to-right shunt via this pulmonary venous return is typically less than 2:1. Variability in the connection between the anomalous right pulmonary vein and the inferior vena cava has also been described. Typically this connection is subdiaphragmatic.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar, 5Farnsworth AE Ankeney JL The spectrum of scimitar syndrome.J Thorac Cardiovasc Surg. 1974; 68: 37-42PubMed Google Scholar However, a supradiaphragmatic venous confluence may also be found.6Mathey J Galey JJ Logeais Y et al.Anomalous pulmonary venous return into inferior vena cava and associated bronchovascular anomalies (the scimitar syndrome): Report of three cases and review of the literature.Thorax. 1968; 23: 107-398Crossref Scopus (40) Google Scholar Other malformations in scimitar syndrome may include diminished lung size, bronchial structural and branching defects, and peculiar lobation. Approximately 90% of right lungs are hypoplastic.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar This diminution in size is likely to be responsible for the dextroversion of the heart present in many cases. Right bronchial abnormalities have been identified by bronchography, bronchoscopy, or in pathologic specimens and cover a vast array of possibilities. Branching defects occur in both large and small airways. The right upper lobe bronchus may be absent, or the distal airways may be sparsely distributed through the lung parenchyma.3Neill CA Ferencz C Sabiston D et al.The familial occurrence of hypoplastic right lung with systemic arterial supply and venous drainage.Bull Johns Hopkins Hosp. 1960; 107: 1-15PubMed Google Scholar In some cases, the branching pattern is the mirror image of that in the left lung. Structurally the bronchi themselves may be small, stenotic, or atretic with areas of diverticulae.7Halasz NA Halloran KH Liebow AA Bronchial and arterial anomalies with drainage of the right lung into the inferior vena cava.Circulation. 1956; 14: 826-846Crossref PubMed Scopus (90) Google Scholar, 8Kiely B Filler J Stone S et al.Syndrome of anomalous venous drainage of the right lung to the inferior vena cava: A review of 67 reported cases and three new cases in children.Am J Cardiol. 1967; 20: 102-116Abstract Full Text PDF Scopus (65) Google Scholar, 9Morgan JR Forker AD Syndrome of hypoplasia of the right lung and dextroposition of the heart: “Scimitar sign” with normal pulmonary venous drainage.Circulation. 1971; 43: 27-30Crossref PubMed Scopus (45) Google Scholar Lobe abnormalities take various forms. Most commonly one lobe is absent, usually the upper lobe, but the middle lobe also may be missing. Hypoplasia of the right lower lobe phenotypically resembles a bilobed lung with a sequestration. But unlike a true sequestration, this hypoplastic lower lobe has direct bronchial communication with the remainder of the bronchial tree.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar Even a unilobate right lung has been described in a patient with scimitar syndrome.10Blondeau P Piwnica A Dubost C The surgical treatment of anomalous pulmonary venous drainage: A report on 25 surgically treated cases.J Cardiovasc Surg. 1961; 2: 37-54Google Scholar Arterial blood supply to the malformed right lung is another highly variable component of scimitar syndrome. Sources of blood flow to the right lung include the right pulmonary artery, bronchial arteries, and anomalous systemic arterial collateral vessels that arise principly from the abdominal aorta or its branches. Whereas bronchial artery abnormalities have not been described, abnormalities in the right pulmonary artery are common. Right pulmonary artery size ranges from normal in 40% of cases5Farnsworth AE Ankeney JL The spectrum of scimitar syndrome.J Thorac Cardiovasc Surg. 1974; 68: 37-42PubMed Google Scholar to atretic or completely absent in rare cases. Most commonly, this artery is hypoplastic. As might be expected, there is a direct correlation between the size of the right pulmonary artery and the size of its corresponding lung.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar Massumi and colleagues11Massumi RA Alwan AO Hernandez TJ et al.The scimitar syndrome: A physiologic explanation for the associated dextroposition of the heart, maldevelopment of the right lung and its artery, and for the systemic collateral supply to the lung.J Thorac Cardiovasc Surg. 1967; 53: 623-633PubMed Google Scholar proposed that pulmonary venous obstruction in the right lung causes venous engorgement and leads to decreased compliance. The relatively noncompliant lung becomes hypoventilated, and alveolar collapse develops. Collapsed alveoli compress capillaries and, coupled with pulmonary venous congestion, shift pulmonary arterial blood flow to the contralateral lung. Consequently, decreased flow in the right pulmonary artery or relatively increased flow to the left lung produces a size discrepancy in the pulmonary arteries proportional to flow and to the size of the right lung. Several authors4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar, 7Halasz NA Halloran KH Liebow AA Bronchial and arterial anomalies with drainage of the right lung into the inferior vena cava.Circulation. 1956; 14: 826-846Crossref PubMed Scopus (90) Google Scholar, 11Massumi RA Alwan AO Hernandez TJ et al.The scimitar syndrome: A physiologic explanation for the associated dextroposition of the heart, maldevelopment of the right lung and its artery, and for the systemic collateral supply to the lung.J Thorac Cardiovasc Surg. 1967; 53: 623-633PubMed Google Scholar have suggested that the anomalous systemic arterial collaterals exist to substitute for this diminished blood flow through the pulmonary artery. The systemic arterial collateral supply to the right lung rarely arises from the thoracic aorta.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar Most typically, it comes from one or more vessels that originate from the abdominal aorta or its branches (Fig 4). These vessels course obliquely and superiorly to pierce the right leaf of the diaphragm and then travel within the inferior pulmonary ligament to reach the lung surface, where they often branch. Their contribution to perfusion of the lung parenchyma is highly variable, ranging from miniscule in very small vessels to complete systemic supply of the right lung when the right pulmonary artery is absent.6Mathey J Galey JJ Logeais Y et al.Anomalous pulmonary venous return into inferior vena cava and associated bronchovascular anomalies (the scimitar syndrome): Report of three cases and review of the literature.Thorax. 1968; 23: 107-398Crossref Scopus (40) Google Scholar Most commonly, however, the systemic arteries supply the right lower lobe or some of its segments.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar, 7Halasz NA Halloran KH Liebow AA Bronchial and arterial anomalies with drainage of the right lung into the inferior vena cava.Circulation. 1956; 14: 826-846Crossref PubMed Scopus (90) Google Scholar, 8Kiely B Filler J Stone S et al.Syndrome of anomalous venous drainage of the right lung to the inferior vena cava: A review of 67 reported cases and three new cases in children.Am J Cardiol. 1967; 20: 102-116Abstract Full Text PDF Scopus (65) Google Scholar, 12Schramel FMNH Westermann CJJ Knaepen PJ et al.The scimitar syndrome: Clinical spectrum and surgical treatment.Eur Respir J. 1995; 8: 196-201Crossref PubMed Scopus (77) Google Scholar Alternatively, flow from these anomalous arteries may supply both the right lower and middle lobes.7Halasz NA Halloran KH Liebow AA Bronchial and arterial anomalies with drainage of the right lung into the inferior vena cava.Circulation. 1956; 14: 826-846Crossref PubMed Scopus (90) Google Scholar When scimitar syndrome is diagnosed in childhood (particularly in infancy), it is associated with several congenital heart defects with incidence ranging from 24% to 100%.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar, 5Farnsworth AE Ankeney JL The spectrum of scimitar syndrome.J Thorac Cardiovasc Surg. 1974; 68: 37-42PubMed Google Scholar, 8Kiely B Filler J Stone S et al.Syndrome of anomalous venous drainage of the right lung to the inferior vena cava: A review of 67 reported cases and three new cases in children.Am J Cardiol. 1967; 20: 102-116Abstract Full Text PDF Scopus (65) Google Scholar, 13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar Atrial septal defect is the most common of these, accounting for 20%–83% of defects.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar, 5Farnsworth AE Ankeney JL The spectrum of scimitar syndrome.J Thorac Cardiovasc Surg. 1974; 68: 37-42PubMed Google Scholar, 13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, 14Gikonyo DK Tandon R Lucas RV et al.Scimitar syndrome in neonates: Report of four eases and review of the literature.Pediatr Cardiol. 1986; 6: 193-197Crossref PubMed Scopus (52) Google Scholar, 15Canter CE Martin TC Spray TL et al.Scimitar syndrome in childhood.Am J Cardiol. 1986; 58: 652-654Abstract Full Text PDF PubMed Scopus (58) Google Scholar Coarctation of the aorta, ventricular septal defect, patent ductus arteriosus, tetralogy of Fallot, and persistent left superior vena cava have also been described.4Folger GM The scimitar syndrome: Anatomic, physiologic, developmental, and therapeutic considerations.Angiology. 1976; 27: 373-407Crossref PubMed Scopus (30) Google Scholar, 5Farnsworth AE Ankeney JL The spectrum of scimitar syndrome.J Thorac Cardiovasc Surg. 1974; 68: 37-42PubMed Google Scholar, 13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, 14Gikonyo DK Tandon R Lucas RV et al.Scimitar syndrome in neonates: Report of four eases and review of the literature.Pediatr Cardiol. 1986; 6: 193-197Crossref PubMed Scopus (52) Google Scholar, 15Canter CE Martin TC Spray TL et al.Scimitar syndrome in childhood.Am J Cardiol. 1986; 58: 652-654Abstract Full Text PDF PubMed Scopus (58) Google Scholar, 16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar Gao and colleagues16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar reported 7 of 13 infants with left-sided lesions, including hypoplastic left ventricle, arch obstruction, subaortic stenosis, pulmonary vein stenosis, and anomalous left coronary artery, all of which are associated with poor outcome. Although patients with scimitar syndrome can have various anatomic manifestations of the disorder, all present with either one of two distinct clinical profiles. In the so-called “adult” form, the patient is either asymptomatic or has recurrent respiratory infections, mild exertional dyspnea, heart murmur, or deformation of the right hemithorax. Occasionally, the scimitar sign is detected on routine chest roentgenogram obtained for unrelated reasons. The adult form has been reported in patients age under 1 year to 73 years, and patients generally tolerate the syndrome well.17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar, 18Honey M Anomalous pulmonary venous drainage of right lung to inferior vena cava (“scimitar syndrome”): Clinical spectrum in older patients and role of surgery.Q J Med (new series XLVI). 1977; 184: 463-483Google Scholar, 19Dupuis C Charaf LAC Breviere GM et al.The “adult” form of the scimitar syndrome.Am J Cardiol. 1992; 70: 502-507Abstract Full Text PDF PubMed Scopus (165) Google Scholar These patients typically do not have pulmonary hypertension and have fewer and less severe associated congenital heart defects, such as secundum atrial septal defect, patent ductus arteriosus, or systemic venous anomalies.15Canter CE Martin TC Spray TL et al.Scimitar syndrome in childhood.Am J Cardiol. 1986; 58: 652-654Abstract Full Text PDF PubMed Scopus (58) Google Scholar, 16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar, 19Dupuis C Charaf LAC Breviere GM et al.The “adult” form of the scimitar syndrome.Am J Cardiol. 1992; 70: 502-507Abstract Full Text PDF PubMed Scopus (165) Google Scholar Systemic arterial collaterals occur in approximately 50% of patients with the adult form, but very few patients in this group receive substantial blood flow to the right lung from these vessels.19Dupuis C Charaf LAC Breviere GM et al.The “adult” form of the scimitar syndrome.Am J Cardiol. 1992; 70: 502-507Abstract Full Text PDF PubMed Scopus (165) Google Scholar Consequently, unless an associated heart anomaly contributes to a left-to-right shunt, the increased ratio of pulmonary to systemic blood flow is caused by the anomalous pulmonary venous return. In such cases of the adult form, this shunt is typically less than 2:1, and the patients lead normal lives. In contrast, patients with the so-called “infantile” form of scimitar syndrome typically present within the first few months of life with failure to thrive, cyanosis, respiratory distress, or congestive heart failure.13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, 14Gikonyo DK Tandon R Lucas RV et al.Scimitar syndrome in neonates: Report of four eases and review of the literature.Pediatr Cardiol. 1986; 6: 193-197Crossref PubMed Scopus (52) Google Scholar, 15Canter CE Martin TC Spray TL et al.Scimitar syndrome in childhood.Am J Cardiol. 1986; 58: 652-654Abstract Full Text PDF PubMed Scopus (58) Google Scholar, 16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar, 20Dupuis C Charaf LAC Breviere GM et al.“Infantile” form of the scimitar syndrome with pulmonary hypertension.Am J Cardiol. 1993; 71: 1326-1330Abstract Full Text PDF PubMed Scopus (108) Google Scholar Sometimes the clinical clues are subtle, such as in an infant who is sick but exhibits only dextroversion on chest roentgenogram. At the other extreme, an infant may have a complex congenital heart defect, such as aortic arch hypoplasia, hypoplastic left heart syndrome, ventricular septal defects, pulmonary vein stenosis, or left ventricular outflow tract obstruction.13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, 14Gikonyo DK Tandon R Lucas RV et al.Scimitar syndrome in neonates: Report of four eases and review of the literature.Pediatr Cardiol. 1986; 6: 193-197Crossref PubMed Scopus (52) Google Scholar, 15Canter CE Martin TC Spray TL et al.Scimitar syndrome in childhood.Am J Cardiol. 1986; 58: 652-654Abstract Full Text PDF PubMed Scopus (58) Google Scholar, 16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar Systemic arterial flow to the right lung is more common in the infantile form than in the adult form. In fact, these systemic arteries supply the lower lobe and sometimes segments of the middle or upper lobes where pulmonary artery branches are lacking.16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 20Dupuis C Charaf LAC Breviere GM et al.“Infantile” form of the scimitar syndrome with pulmonary hypertension.Am J Cardiol. 1993; 71: 1326-1330Abstract Full Text PDF PubMed Scopus (108) Google Scholar, 21Haworth SG Sauer U Buhlmeyer K Pulmonary hypertension in scimitar syndrome in infancy.Br Heart J. 1983; 50: 182-189Crossref PubMed Scopus (47) Google Scholar Another characteristic of the infantile form (and often the factor responsible for the severe symptoms as well as the poor prognosis of this form) is pulmonary hypertension, which has been reported in 43–100% of patients with this form.13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, 15Canter CE Martin TC Spray TL et al.Scimitar syndrome in childhood.Am J Cardiol. 1986; 58: 652-654Abstract Full Text PDF PubMed Scopus (58) Google Scholar, 16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar, 20Dupuis C Charaf LAC Breviere GM et al.“Infantile” form of the scimitar syndrome with pulmonary hypertension.Am J Cardiol. 1993; 71: 1326-1330Abstract Full Text PDF PubMed Scopus (108) Google Scholar Factors thought to contribute to the pulmonary hypertension include (1) a left-to-right shunt from the anomalous pulmonary vein to the inferior vena cava; (2) stenosis of the scimitar vein or other pulmonary veins; (3) an associated intracardiac shunt, such as a ventricular septal defect; (4) reduction of the right pulmonary vascular bed due to lung hypoplasia; (5) failure of the pulmonary circulation to adapt postnatally in the face of excessive pulmonary blood flow21Haworth SG Sauer U Buhlmeyer K Pulmonary hypertension in scimitar syndrome in infancy.Br Heart J. 1983; 50: 182-189Crossref PubMed Scopus (47) Google Scholar; and (6) a left-to-right shunt from the systemic arteries that supply the right lung to the pulmonary veins and ultimately to the inferior vena cava. Some authors propose that the systemic arterial shunt is the primary cause of the symptoms and the origin of the pulmonary hypertension in the infantile form.20Dupuis C Charaf LAC Breviere GM et al.“Infantile” form of the scimitar syndrome with pulmonary hypertension.Am J Cardiol. 1993; 71: 1326-1330Abstract Full Text PDF PubMed Scopus (108) Google Scholar, 21Haworth SG Sauer U Buhlmeyer K Pulmonary hypertension in scimitar syndrome in infancy.Br Heart J. 1983; 50: 182-189Crossref PubMed Scopus (47) Google Scholar, 22Dickinson DF Galloway RW Massey R et al.Scimitar syndrome in infancy: Role of embolisation of systemic arterial supply to right lung.Br Heart J. 1982; 47: 468-472Crossref PubMed Scopus (35) Google Scholar In any patient with suspected scimitar syndrome, both right and left heart catheterizations are needed to confirm the diagnosis. Angiography of the heart's right side will demonstrate the anomalous pulmonary vein and pulmonary artery anatomy, whereas aortography will delineate the systemic collateral supply to the right lung. Hemodynamic measurements will detect pulmonary hypertension if present, and hemoglobin saturation data are used to calculate shunt fractions. In a patient presenting with predominantly respiratory infection or dyspnea, bronchoscopy, computed tomography of the chest, bronchography, and ventilation scintigraphy may be used to evaluate the bronchial anatomy and estimate functional lung volume. Currently, no single therapy is considered superior for treating scimitar syndrome. Because this anomaly is rare, prospective randomized evaluation would require a lengthy study and the participation of multiple centers. In addition, the long study duration would add other variables, such as changes in medical technology, patient care, and surgical expertise, which may impact significantly on outcome. The literature to date reports several small series each of which spans multiple decades, and it is from these data that we outline the therapeutic options for scimilar syndrome. Most authors agree that systemic arterial collaterals should be eliminated to treat pulmonary hypertension and heart failure.13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, 15Canter CE Martin TC Spray TL et al.Scimitar syndrome in childhood.Am J Cardiol. 1986; 58: 652-654Abstract Full Text PDF PubMed Scopus (58) Google Scholar, 16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar, 20Dupuis C Charaf LAC Breviere GM et al.“Infantile” form of the scimitar syndrome with pulmonary hypertension.Am J Cardiol. 1993; 71: 1326-1330Abstract Full Text PDF PubMed Scopus (108) Google Scholar, 21Haworth SG Sauer U Buhlmeyer K Pulmonary hypertension in scimitar syndrome in infancy.Br Heart J. 1983; 50: 182-189Crossref PubMed Scopus (47) Google Scholar, 22Dickinson DF Galloway RW Massey R et al.Scimitar syndrome in infancy: Role of embolisation of systemic arterial supply to right lung.Br Heart J. 1982; 47: 468-472Crossref PubMed Scopus (35) Google Scholar These vessels can be surgically ligated or embolized through catheter-based techniques. Any additional left-to-right shunt exceeding 2:1 should be corrected. However, preoperative studies should determine whether an associated cardiac defect, the anomalous pulmonary venous return, or both contribute significantly to the shunt. When the scimitar venous flow accounts for less than a 2:1 shunt by itself, surgical correction may be unnecessary. In contrast, when the left-to-right shunt through the scimitar vein exceeds 50%, this flow should be redirected into the left atrium by one of various techniques to lessen the volume load on the right ventricle and decrease the risk of late arrhythmias and exercise intolerance. Three options are available for such a repair: (1) The scimitar vein can be disconnected from the inferior vena cava and an anastomosis made between it and the left atrium directly or to the right atrium and the flow channled through the atrial septum by suturing an intra-atrial baffle; (2) the anomalous connection between the scimitar vein and the inferior vena cava can be left intact and a long baffle fashioned to redirect flow from this connection to the left atrium across the septum; or (3) the anomalous vein and the right atrium can be incised in parallel and then both openings sutured together to form a wide anastomosis. An intraatrial baffle is then placed to guide flow from this anastomosis to the left atrium across an atrial septal defect. In some cases, a staged approach in which ligation or embolization of the systemic arterial collaterals is followed by surgical repair of the anomalous pulmonary venous return may be advantageous.16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 21Haworth SG Sauer U Buhlmeyer K Pulmonary hypertension in scimitar syndrome in infancy.Br Heart J. 1983; 50: 182-189Crossref PubMed Scopus (47) Google Scholar, 22Dickinson DF Galloway RW Massey R et al.Scimitar syndrome in infancy: Role of embolisation of systemic arterial supply to right lung.Br Heart J. 1982; 47: 468-472Crossref PubMed Scopus (35) Google Scholar Lobectomy or pneunonectomy is best reserved for patients with recurrent infection, persistent hemoptysis, thrombosed intra-atrial baffles, or marked hypoplasia of the right lung. The results for treating scimitar syndrome must be evaluated while keeping several factors in mind. First, the infantile form of the disease is more severe than the adult form. Second, most studies are small and retrospective, and thus conclusions about optimal therapy are based in part on chance outcomes, not necessarily outcomes resulting from a specific intervention. Third, because this syndrome is rare, all studies have been compiled over several decades. As such, these studies do not account for changes in surgical technique and in the care of critically ill patients that have evolved over the study periods. But despite these limitations, useful information obtained by many investigators forms the basis for treatment recommendations for scimitar syndrome. In the infantile form of scimitar syndrome, medical management typically carries a mortality of 33–100%.13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, 15Canter CE Martin TC Spray TL et al.Scimitar syndrome in childhood.Am J Cardiol. 1986; 58: 652-654Abstract Full Text PDF PubMed Scopus (58) Google Scholar, 16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 20Dupuis C Charaf LAC Breviere GM et al.“Infantile” form of the scimitar syndrome with pulmonary hypertension.Am J Cardiol. 1993; 71: 1326-1330Abstract Full Text PDF PubMed Scopus (108) Google Scholar Conversely, a single study from Najm and colleagues17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar showed only one of seven infant deaths in those not undergoing surgery or catheter-based intervention. However, whether these seven infants had pulmonary hypertension or heart failure is unclear from this study. This information is important based on data from Dupuis and associates,20Dupuis C Charaf LAC Breviere GM et al.“Infantile” form of the scimitar syndrome with pulmonary hypertension.Am J Cardiol. 1993; 71: 1326-1330Abstract Full Text PDF PubMed Scopus (108) Google Scholar who reported on 25 patients with the infantile form of scimitar syndrome. Ten of these patients were treated medically, and mortality was 70%. These authors reported that the severity of symptoms, level of pulmonary pressure, and a younger age of presentation all influenced prognosis. The surgical approach to the infantile form of scimitar syndrome has varied. Occlusion of the systemic arterial collaterals alone, either by surgical ligation or catheter embolization, is associated with poor results, with a mortality of 16–60%.13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, 15Canter CE Martin TC Spray TL et al.Scimitar syndrome in childhood.Am J Cardiol. 1986; 58: 652-654Abstract Full Text PDF PubMed Scopus (58) Google Scholar, 16Gao YA Burrows PE Benson LN et al.Scimitar syndrome in infancy.J Am Coll Cardiol. 1993; 22: 873-882Abstract Full Text PDF PubMed Scopus (120) Google Scholar, 17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar, 20Dupuis C Charaf LAC Breviere GM et al.“Infantile” form of the scimitar syndrome with pulmonary hypertension.Am J Cardiol. 1993; 71: 1326-1330Abstract Full Text PDF PubMed Scopus (108) Google Scholar The long baffle repair has been associated with stenosis17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar or occlusion,13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar and subsequent pneumonectomy is often necessary. Division of the scimitar vein and reimplantation into either the left atrium or the right atrium with construction of an intra-atrial baffle has been done with possibly improved results. Huddleston and coworkers13Huddleston CB Exil V Canter CE et al.Scimitar syndrome presenting in infancy.Ann Thorac Surg. 1999; 67: 154-160Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar reported that five patients treated with this technique were alive and well at midterm follow-up. However, only three patients required no further treatment. One patient underwent pneumonectomy for baffle occlusion, and another received a lung transplant for bilateral pulmonary vein stenosis. Medical management for the adult form of scimitar syndrome has produced good results. Dupuis and colleagues19Dupuis C Charaf LAC Breviere GM et al.The “adult” form of the scimitar syndrome.Am J Cardiol. 1992; 70: 502-507Abstract Full Text PDF PubMed Scopus (165) Google Scholar reported on 122 patients, 85 of whom did not undergo surgery; 79 of these 85 were alive and well. Two patients had chronic bronchitis and four had recurrent hemoptysis, but all six were able to conduct normal lives. In comparison, the 37 patients who underwent surgical repair, involving division of the scimitar vein and reimplantation into the left atrium, had mixed results. Twelve patients (33%) had a good outcome; 21 suffered postoperative respiratory complications and ultimately had poor long-term results. In addition, there was an 11% operative mortality not seen in the medically managed patients. The poorer outcomes for many surgically treated patients were attributed to thrombosis of the venoatrial anastomosis. Schramel12Schramel FMNH Westermann CJJ Knaepen PJ et al.The scimitar syndrome: Clinical spectrum and surgical treatment.Eur Respir J. 1995; 8: 196-201Crossref PubMed Scopus (77) Google Scholar noted a similar result in a smaller series. Interestingly, the long baffle technique has produced better results in the adult form than in the infant form. However, it has shortcomings. Murphy and associates23Murphy JW Kerr AR Kirklin JW Intracardiac repair for anomalous pulmonary venous connection of right lung to inferior vena cava.Ann Thorac Surg. 1971; 11: 38-42Abstract Full Text PDF PubMed Scopus (19) Google Scholar reported that five of six patients had a good short-term outcome, but the sixth patient had an immediate postoperative death. Similarly, in the series from Najm,17Najm HK Williams WG Coles JG et al.Scimitar syndrome: Twenty years' experience and results of repair.J Thorac Cardiovasc Surg. 1996; 112: 1161-1169Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar two of 11 (18%) adult patients who underwent long baffle repair developed pulmonary vein stenosis. One of these patients had the baffle excised, the atrial septal defect closed, and the scimitar vein left intact. Regardless of whether the long baffle technique or division and reimplantation of the scimitar vein into an atrium is used, pulmonary venous stenosis, obstruction, and thrombosis remain the major obstacles to a successful repair in scimitar syndrome. As an alternative repair, we propose a side-to-side venoatrial anastomosis (13, 14, 15). This technique provides a widely patent anastomosis and allows for a short baffle. Compared to the long baffle repair, in which pulmonary venous blood flow must course through a sharp angle and be redirected nearly 180°, the side-to-side anastomosis allows for direct flow across the baffle to the left atrium on a horizontal plane (Fig 16). Compared to division of the scimitar vein and creation of an end-to-side venoatrial anastomosis, the side-to-side connection is larger and potentially less prone to hemodynamically significant stenosis. Although this side-to-side anastomosis has not been tested in a formal study, it theoretically will reduce anastomotic stenosis, stasis of blood flow, and pulmonary venous thrombosis. Scimitar syndrome is a complex anomaly comprising various vascular, bronchial, and parenchymal derangements of the right lung. The clinical phenotypes are the infantile and adult forms. The infantile form is characterized by heart failure, pulmonary hypertension, associated cardiac defects, and a presentation before age 1 year. Therapy is best directed at correcting all malformations early. Occlusion of the arterial collaterals can be done as part of a complete surgical repair or by catheter embolization to temporize very ill infants. Associated heart malformations, particularly left-sided obstructing lesions or others that contribute to pulmonary hypertension, should be corrected surgically along with repair of the anomalous pulmonary venous drainage. Medical management is ineffective in treating the infantile form.
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