Ann Thorac Surg 2009;88:1685-1687. doi:10.1016/j.athoracsur.2009.03.056
© 2009 The Society of Thoracic Surgeons
Case Reports
Isolated Subclavian Artery: Anatomical and Surgical Considerations
Igor E. Konstantinov, MD, PhD*,
Pankaj Saxena, MCh, DNB,
Yves d'Udekem, MD, PhD,
Christian P. Brizard, MD
Department of Cardiac Surgery, Royal Children's Hospital, Melbourne, Australia
Accepted for publication March 18, 2009.
* Address correspondence to Dr Konstantinov, Royal Children's Hospital, Flemington Rd, Parkville, VIC 6009, Australia (Email: igor.konstantinov{at}rch.org.au).
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Abstract
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Isolated subclavial artery is a rare congenital anomaly. Herein we discuss a patient with isolated left subclavian artery and bilateral patent arterial ducts who underwent sucessful repair. We also describe the detailed anatomy of both recurrent nerves in this condition and embryology of the anomaly.
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Introduction
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Isolated subclavian artery is a rare anomaly of the aortic arch in which one subclavian artery loses its connection to the aorta and arises from the pulmonary artery (PA) on the same side by means of a ductus arteriosus, whether closed or patent [1]. Since its original description by Dr Anton Ghon [2] in 1908, a fewer than 100 cases were reported in the world's literature [1, 3–5]. Surgical experience is limited to a handful of case reports. Understanding the anatomy of recurrent nerves is helpful in the successful surgical management of this rare anomaly.
A 2-month-old boy (4.2 kg) with 22q11 deletion and DiGeorge syndrome presented with failure to thrive and a classic loud machinery murmur. A large patent ductus arteriosus (PDA) was diagnosed, and surgical closure of the PDA through the left posterolateral thoracotomy was attempted elsewhere. However, no PDA or aorta could be visualized through this approach. A subsequent computed tomographic scan demonstrated isolated origin of the left subclavian artery (LSCA) from the left PA (Figs 1A–1C), a right aortic arch with a right-sided descending aorta (Fig 1D), and a large right PDA (Figs 1E and 1F). The patient was referred to our unit for further management. Blood pressure was the same in all limbs. The head and neck ultrasound demonstrated flow reversal in the left vertebral artery. A midline sternotomy was performed. There was no thymus. The right PDA was closed with a metal clip, the left common carotid artery and LSCA were dissected, and both recurrent nerves were visualized (Fig 2). The subclavian artery was detached from the pulmonary artery and anastomosed to the left common carotid artery. Cardiopulmonary bypass was not required. The patient was discharged home after an uneventful postoperative course.
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Fig 1. Computed tomographic scan demonstrating (A–C) isolated origin of the left subclavian artery from the pulmonary artery, (D) the right aortic arch with right-sided descending aorta, and (E, F) a large patent ductus arteriosus.
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Fig 2. Involution of (A) the left fourth aortic arch around the origin of the seventh intersegmental (subclavian) artery (B) leaves the left subclavian artery (LSCA) attached to the pulmonary artery through the left patent ductus arteriosus (PDA) (remnant of the sixth aortic arch). (C, D) Both recurrent nerves travel their usual course around the remnants of the sixth aortic arches. (D) The right PDA was closed with a clip and the LSCA was anastomosed to the left common carotid artery (LCCA). (RCCA = right common carotid artery; RSCA = right subclavian artery.)
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Comment
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The described anomaly derives from an unusual involution of the double fourth aortic arch [2] when the breaks occur between the left common carotid artery and the LSCA, and the LSCA and the descending aorta as well as the bilateral patent arterial ducts and the dorsal remnants of the sixth (pulmonary) embryonic aortic arches (Figs 2A and 2B). Thus, the LSCA remains attached to the pulmonary artery though the left PDA (Figs 2B and 2C). Clear understanding of the course of the recurrent nerves in this rare anomaly is a must for successful repair. The recurrent nerve derives from the vagus nerve that enters the thorax through the carotid sheath adjacent to the common carotid artery, and as such, is always anterior to subclavian artery. The recurrent nerve then turns around the remnants of the sixth aortic arch and travels to the vocal cords in the tracheo-esophageal groove (Fig 2C). Both recurrent nerves were clearly visualized in our patient during surgery (Fig 2D). Because the LSCA is connected to the PA through the left PDA, and to the left vertebral artery cephalically, both the "pulmonary steal phenomenon" from retrograde filling of the PA and "subclavian steal phenomenon" from retrograde circulation in the vertebrobasilar system may occur [2, 3]. Despite the fact that there was no discrepancy in blood pressure in both arms in our patient, the preoperative demonstration of the retrograde flow in the left vertebral artery suggested a potential for subclavian steal syndrome. Thus, the LSCA was implanted into the left common carotid artery to prevent postoperative steal phenomena. Midline sternotomy provided an excellent exposure. Due to frequent association of chromosome 22q11 deletion and anomalies of aortic arch laterality and branching [4], the exact anatomy of the arch must be delineated in each patient with this genetic anomaly prior to any attempt of PDA ligation. The laterality and branching of the aortic arch can be demonstrated in most patients by echocardiography alone. If echocardiography is inconclusive, however, a computed tomographic scan is helpful.
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References
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- Nath PH, Castaneda-Zuniga W, Zollikofer C, et al. Isolation of a subclavian artery Am J Roentgenol 1981;137:683-688.[Abstract/Free Full Text]
- Ghon A. Ueber eine seltene Entwicklungs-storung des Gefassystem Verh Dtsch Ges Pathol 1908;12:242-247.
- McMahon CJ, Thompson KS, Kearney DL, Nihill MR. Subclavian steal syndrome in anomalous connection of the left subclavian artery to the pulmonary artery in d-transposition of the great arteries Pediatr Cardiol 2001;22:60-62.[Medline]
- McElhinney DB, Clark BJ, Weinberg PM, et al. Association of chromosome 22q11 deletion with isolated anomalies of the aortic arch laterality and branching J Am Coll Cardiol 2001;37:2114-2119.[Abstract/Free Full Text]
- Madan N, Schneider DJ, Jacobs ML. Right aortic arch, isolated left subclavian artery and ductus arteriosus with normal intracardiac anatomy: rare manifestation of chromosome 22q11 deletion Pediatr Cardiol 2006;27:781-783.[Medline]
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Abstract
Introduction
