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Interact CardioVasc Thorac Surg 2009;8:277-279. doi:10.1510/icvts.2008.188201 © 2009 European Association of Cardio-Thoracic Surgery
Absent left pulmonary artery and double aortic arch in tetralogy of Fallot: reconstruction using homograft saphenous vein or iliac arteryDepartment of Cardiothoracic and Vascular Surgery, All India Institute of Medical Sciences, New Delhi-110029, India Received 14 July 2008; received in revised form 10 October 2008; accepted 13 October 2008
*Corresponding author. Tel.: +91-11-26593373; fax: +91-11-265862663.
Two cases of tetralogy of Fallot (TOF) with double aortic arch and absent left pulmonary artery are reported. Single-stage repair was performed using a left thoracotomy for division of the non-dominant arch followed by complete repair through a median sternotomy. In both patients, the left pulmonary artery was reconstructed using either a homograft saphenous vein or a homograft common iliac artery.
Key Words: Tetralogy of Fallot; Aortic arch anomalies; Absent pulmonary artery
Absent left pulmonary artery (LPA) is a rare accompaniment of tetralogy of Fallot (TOF) [1]. Double aortic arch has been described with TOF [2]. To the best of our knowledge, TOF with double aortic arch and absent pericardial LPA has not been reported in English medical literature. We report two such cases. In both patients the absent pulmonary artery was reconstructed using homograft tissue. A 9-year-old male patient was referred to us for intracardiac repair of TOF. He had undergone a right modified Blalock–Taussig shunt with a 5-mm PTFE interposition graft through a right posterolateral thoracotomy four years previously. Echocardiography suggested a diagnosis of TOF, double aortic arch and absent LPA, which was later confirmed on cardiac catheterization (Fig. 1). CT angiography revealed a 4.5-mm hilar LPA. The circulation to the left lung was maintained through small collateral arteries from the intercostals and the left subclavian artery. However, none of these was sufficiently large to be unifocalized/coil embolized. The right-sided arch was dominant with mild extrinsic compression over the distal-most part of the trachea due to the vascular ring; however, there were no symptoms or signs due to tracheal compression. The right shunt was patent.
A left posterolateral thoracotomy was performed via the 4th intercostal space and the non-dominant left aortic arch was divided. The hilar LPA was dissected and anastomosed to a reversed segment of an antibiotic preserved homograft saphenous vein of 7 mm diameter and 8 cm in length after heparinization. A pericardial window was made posterior to the phrenic nerve and the other end of the homograft vein was fixed to the pericardial window with a metallic clip. The thoracotomy was closed, the patient was turned in a supine position and after a median sternotomy, the previously performed right shunt was dissected, cardiopulmonary bypass was instituted and the shunt occluded. The homograft saphenous vein was delivered and anastomosed to the main pulmonary artery in an end-to-side fashion. After cardioplegic arrest, the ventricular septal defect was closed through the right atrium, the infundibular muscle was resected through a limited right ventriculotomy and an autologous pericardial patch was used to reconstruct the right ventricular outflow tract in which a monocusp valve of autologous pericardium was placed to prevent free pulmonary regurgitation. After 1 year of surgery, the patient is asymptomatic with normal activity. Echocardiography revealed good flow into the reconstructed LPA with no other residual defect. A 12-year-old male presented with dyspnea on exertion and cyanosis. There was no history of stidor or dysphagia. Plain radiograph of the chest revealed decreased pulmonary vascular markings, more on the left side. After echocardiography and cineangiography, the diagnosis of TOF, LPA atresia and double aortic arch was made. CT angiography revealed the non-dominant left arch and a distal and hilar LPA (Fig. 2). The LPA filled faintly via small collaterals from the intercostal and subclavian arteries. A left posterolateral thoracotomy was performed and the non-dominant left aortic arch was divided. The thoracotomy was closed and the patient turned in a supine position and a median sternotomy was performed followed by institution of cardiopulmonary bypass. The main and both branch pulmonary arteries were dissected. LPA was further dissected till the hilum. An antibiotic preserved homograft common iliac artery of 8 mm diameter and 4 cm in length was anastomosed to the distal LPA and then to the MPA. The rest of the operation was similar to the first patient. Postoperative course was uneventful and after 23 months of follow-up the patient is in NYHA class I and off cardiac medications. Echocardiography revealed good flow into the reconstructed LPA with no other residual defect.
Follow-up cardiac catherterization and cineangiography has not been performed so far to study the balance of circulation to either lung in both these patients. However, follow-up echocardiograms have revealed satisfactory flow into the reconstructed LPA without any gradients.
When unilateral absence of a pulmonary artery (UAPA) is considered, absent RPA is more frequently encountered than an absent LPA and occurs as an isolated lesion. On the other hand, absence of LPA is associated with intracardiac anomalies. In TOF with UAPA, absent LPA is 5–8 times more frequent than RPA [5] and is often associated with a right aortic arch [3]. Cucci et al. [4] suggest that TOF with absent LPA can be explained by dorso-rotation of left trunco-conal ridge. This causes incorporation of the left sixth aortic arch into the ascending aorta and hypoplasia of pulmonary trunk and right ventricular outflow. The trunco-conal and muscular ventricular septa lie in different planes leading to mal-aligned VSD and aortic override. A rightward slant of the distal end of the ascending aorta causes preferential flow in the right side of the dorsal aorta. This causes the right side to become the definitive arch. As the left fourth arch and right dorsal aorta gets less blood from the ascending aorta and no blood from pulmonary circulation, it involutes. If this involution is incomplete the patient may develop TOF with absent LPA and double aortic arch. The LPA can have a systemic origin from aorta or innominate artery or it may completely involute. However, this theory does not explain TOF with absent RPA. Acquired atresia may be secondary to pulmonary artery thrombosis resulting from hypercoagulable state in TOF [5]. The lung on the side of the absent pulmonary artery is usually well developed and supplied by intercostal vessels, collaterals and sometimes by a distal segment of pulmonary artery connected to a systemic vessel with a patent ductus or directly. Therefore, in the presence of a distal pulmonary artery or hilar pulmonary artery, reconstruction can be attempted. ‘Ideal’ repair of TOF with UAPA is aimed at correcting intracardiac defects and restoring physiologic blood flow in the ipsilateral lung [3]. However, such operations are rare and are described mostly in neonates with isolated UAPA. Reconstruction of the absent pulmonary artery may be performed by direct anastomosis after mobilization of the main and distal pulmonary artery [6] or use of autologous and prosthetic conduits (Dacron/Gore-Tex) [7, 8]. The disadvantages of using prosthetic material as conduits are lesser patency rates and the need for antiplatelet agents. Autologous saphenous vein, pericardial tube graft and reverse rotational U-shaped flap from the single pulmonary artery have also been used [9, 10]. These may be ideal but the availability of an adequate size autologous saphenous vein is often a drawback. We were able to obtain and used a suitably sized homograft saphenous vein and homograft common iliac artery from the homograft tissue bank at our institution. We did not have to alter the already existing MPA and the single pulmonary artery. We believe that these techniques are simple and reproducible in most patients in which hilar pulmonary can be identified.
The authors thank Dr T.K. Susheel Kumar, Fellow in Cardiovascular Surgery at the Children's National Medical Center, Washington DC for supplying Fig. 1.
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Abstract
1. Introduction
