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Scimitar syndrome is a rare but serious congenital condition that consists of anomalous pulmonary venous drainage of the right lung to the inferior vena cava. The appearance on chest radiography resembles a curved Turkish sword, or scimitar. Scimitar syndrome is associated with other anomalies, including hypoplasia of the right lung, dextroposition of the heart, anomalous systemic arterial supply to the right lung, and atrial septal defect. Clinical manifestations in infants include severe tachypnea and cyanosis. Adult patients may present with dyspnea and increased fatigue. Few adult cases have been reported in the medical literature. Classical surgical repair involves diversion of the scimitar venous flow into the left atrium with a baffle, requiring the use of cardiopulmonary bypass and deep hypothermic circulatory arrest. Herein, we report the case of a 42-year-old woman with 2 scimitar veins who underwent corrective surgery at our center without the use of cardiopulmonary bypass. We also comment on the importance of a patient's lung hypoplasia in the decision to repair the defect through a right thoracotomy.
Scimitar syndrome is defined as anomalous pulmonary venous drainage from the right lung to the inferior vena cava (IVC). The variability of this congenital condition has been well described.1 The scimitar vein normally enters the IVC below the level of the diaphragm, and the entire venous drainage of the right lung flows through the scimitar vein. However, occasionally the scimitar vein drains only the middle or lower lobe. Anomalous drainage from the left lung has also been described.2 The scimitar vein most often descends anterior to the hilum, grows larger as pulmonary veins drain into it, and curves slightly to the left to join the IVC. This creates a distinctive shape on chest radiography that resembles a curved Turkish sword, or scimitar, as described by Halasz and colleagues in 1956.3
Classically divided into an infantile and a pediatric/adult form,4,5 scimitar syndrome occurs in 2 of 100,000 births and is twice as common in females.6 Among affected persons, the scimitar sign is present in 70% of pediatric and adult patients but in less than 10% of infants. Coexisting anomalies can include hypoplasia of the right lung, systemic arterial blood supply to the right lung from the aorta (in 60% of cases), atrial septal defect (ASD, in 40% of affected patients), and dextroposition of the heart.6 Infants often present with severe tachypnea, cyanosis, and signs of congestive heart failure due to a substantial left-to-right shunt, resulting in failure to thrive. In contrast, children and adults are often asymptomatic or they may present with symptoms such as recurrent pneumonia, mild dyspnea, or increased fatigue. Dextroposition of the heart occurs less frequently in adults than in children but is more challenging to repair. Surgical techniques for repair of scimitar syndrome have varied widely, and few cases involving adults have been reported. Herein, we report the case of an adult patient with 2 scimitar veins who underwent corrective surgery through a right thoracotomy without cardiopulmonary bypass (CPB).
In September 2008, a 42-year-old woman presented with recurrent dyspnea and increasing fatigue. Her medical history included hypothyroidism and pneumonia. Her surgical history included the creation of a pericardial window for a pericardial effusion in 2001. In 2006, she had begun experiencing increased shortness of breath, tachycardia, and chest pain, accompanied by numbness and paresthesia extending into the left arm. That same year, she had a syncopal episode that was attributed to vertigo. Results of a computed tomographic scan of the head were normal. In 2007, she experienced another syncopal episode, and her other symptoms recurred. Computed tomography of the thorax at that time revealed partial anomalous pulmonary venous return with the right pulmonary veins draining into the IVC, hypoplasia of the right lung, dextroposition of the heart, and an ASD. At the current presentation, coronary angiography of the right heart revealed a Qp/Qs ratio of 2.4:1 (Fig. 1). Subsequent angiography of the left heart showed normal coronary arteries. The patient was admitted for surgical correction.
Repair was undertaken through a right lateral thoracotomy via the 6th intercostal space, without the use of CPB, circulatory arrest, or deep hypothermia. During the operation, we discovered 2 descending scimitar veins: the larger vein drained the lower and middle lobes of the right lung, and the smaller vein drained the upper lobe. The scimitar veins traveled anterior to the hilum, descended below the level of the diaphragm, and entered the IVC just above the hepatic veins. Because of the hypoplasia of the right lung, the heart was rotated rightward and posteriorly, which caused the left atrium and IVC to be facing away from the operative field and the atrial septum to be displaced so that it was no longer parallel to the spine.
Three major aortopulmonary collateral vessels from the aorta created dual perfusion to the hypoplastic right lung. These vessels were ligated and transected. The right pulmonary artery was snared with an umbilical tape, and the right lung was cooled with ice. The scimitar veins were circumferentially dissected, mobilized, and detached from the IVC. They were aligned side by side, and their opposing walls were incised and then sewn to each other so that there was a common venous confluence. The left atrium was rotated into view. The intra-atrial groove was developed. The left atrium was partially clamped and then incised, with care taken not to traverse the septum and enter the right atrium. (This proved to be quite difficult, because the left atrium was rotated away from the operative field.) A window of pericardium was excised posterior to the phrenic nerve, and the common vein was sewn to the left atrium. Transesophageal echocardiography revealed close positioning of the common vein to the septum, with unobstructed flow. The patient's recovery was uneventful. At her follow-up examination 16 months postoperatively, she was asymptomatic and doing well, with no echocardiographic evidence of pulmonary venous obstruction.
In patients who have the adult form of scimitar syndrome, symptoms usually occur during the 5th decade of life, which is when both of Gudjonsson and Brown's adult patients underwent operative repair.6 Our 42-year-old patient was considered for operative repair because of her recurrent symptoms. To avoid using CPB and deep hypothermic circulatory arrest, we used an apporach that was first described by Brown and colleagues in 2003.7 A lateral right thoracotomy in the 6th intercostal space adequately exposed the 2 scimitar veins, and we decided to sew the veins together and to anastomose the new vessel directly to the left atrium. This is in contrast with the classical repair, wherein the scimitar venous flow into the IVC is redirected to the left atrium via a baffle; this approach always requires CPB and, almost always, circulatory arrest. In our patient, it was possible but challenging to construct the venous anastomosis. During the operation, it was crucial to ensure that the partial clamp was actually on the left atrium, that the septum was not incised, and that the right atrium was not entered.
Because of the hypoplasia of the right lung, our patient's heart was rotated rightward and posteriorly, which turned the left atrium away from the operative field—the atrial septum was no longer parallel to the spine. Preoperative understanding of the severity of hypoplasia is important, because the degree to which the left atrium is rotated away from the right thoracotomy affects the ease or difficulty of repair.
Surgical correction of scimitar syndrome with preservation of the lung generally requires that blood from the anomalous vein be routed into the left atrium.8 It was previously thought that the scimitar vein was too short to mobilize and suture directly to the left atrium, because doing so might cause vessel distortion and thrombosis. The 1st corrective operation for scimitar syndrome was performed by Kirklin and associates9 in 1956. Zubiate and Kay10 described how to use a pericardial tunnel or synthetic patch to direct flow from the scimitar vein through the right atrium and into the left atrium. Shumacker and Judd11 proposed excising the scimitar vein, reimplanting it into the right atrium, and using a patch to direct flow to the left atrium through an existing ASD. This classical correction of scimitar syndrome, which surgeons still perform, requires circulatory arrest and deep hypothermia.12 Dupuis and co-authors4 described a series of 37 patients who underwent classical surgical repair; only 12 reportedly had acceptable results and no thrombosis. This finding cast doubt on the usefulness of corrective surgery in adults with scimitar syndrome. In addition, if a scimitar vein travels posterior to the hilum or follows another complex course, kinking and subsequent obstruction of the vein is not rare. Therefore, Huddleston and colleagues13 suggested that right pneumonectomy may be a possible alternative approach. In contrast, Gudjonsson and Brown6 reported a series of cases that involved scimitar vein repair through right thoracotomy. During the mean follow-up period of 5 years, no patients died, and none required reoperation to correct stenosis or thrombosis of the scimitar vein.
A right thoracotomy is not the ideal approach in all patients. If the surgeon performs a right thoracotomy and dissection and realizes that gaining access to the left atrium will be too difficult or that anastomosis cannot be safely performed without kinking the vein, 1 alternative might be to sew the vein into the right atrium. The surgeon could then return by sternotomy and construct a simple baffle to the ASD without the use of circulatory arrest.
In summary, we used a safe and effective approach to surgically treat an adult who had 2 scimitar veins, without the risks associated with extracorporeal circulation and deep hypothermic circulatory arrest. We recommend the use of the described procedure in adult patients with scimitar syndrome who do not have significant hypoplasia of the right lung.
Stephen N. Palmer, PhD, ELS, contributed to the editing of this report.
Address for reprints: David L.S. Morales, MD, Division of Congenital Heart Surgery, Texas Children's Hospital, Houston, TX 77030