Ann Thorac Surg 2007;83:2226-2228
© 2007 The Society of Thoracic Surgeons
Case Reports
Rare Presentation of Subclavian Artery Isolation in a Neonate With a Family History of Aortic Arch Anomalies
Hutan Ashrafian, MRCS*,
Victor Tsang, MD, FRCS,
Martin Kostolny, MD
Department of Cardiothoracic Surgery, London, United Kingdom
Accepted for publication November 13, 2006.
* Address correspondence to Dr Ashrafian, Department of Cardiothoracic Surgery, Great Ormond Street Hospital, London, WC1N 3JH, United Kingdom (Email: ashrafian{at}email.com).
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Abstract
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Isolation of the left subclavian artery is a rare aortic arch anomaly in which the artery originates from the pulmonary artery through a ductus arteriosus rather than the aorta. In neonates it is usually diagnosed incidentally with other aortic or cardiac anomalies and can be associated with chromosomal deletions. We describe an extremely rare presentation whereby subclavian artery isolation was presented with left arm ischemia in a 6-day-old child. There were also a concurrent right aortic arch, ventricular septal defect, persistent left superior vena cava, and both radial and ulnar artery hypoplasia. A family history of aortic arch anomalies with no known chromosomal aberration was also present, whereby all the male family members on the maternal side had undergone aorto-cardiac surgery as neonates. Diagnosis and surgical management are discussed.
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Introduction
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Isolation of the left subclavian artery is a rare aortic arch anomaly in which the artery originates from the pulmonary artery through a ductus arteriosus rather than the aorta. This is usually diagnosed incidentally with other aortic or cardiac pathologies when presenting in neonates, and it can be associated with chromosomal deletions. We report an extremely rare case of presentation as a left arm ischemia with a family history of aortic arch pathology and no known chromosomal aberrations. After diagnosis the patient underwent successful surgical correction.
A male infant was born at full-term. This baby boy was born from the first pregnancy of a healthy 35-year-old mother without antenatal problems. Initial clinical examination was unremarkable other than a pansystolic murmur attributable to a ventricular septal defect detected on antenatal ultrasound. Family history included combined aortic coarctation and ventricular septal defect in one male cousin and hypoplastic left heart syndrome in another male cousin from two maternal sisters; one cousin who had undergone prior surgical repair at our institution [1]. The neonate was stable and discharged home with instructions for cardiological follow-up.
The baby boy was readmitted to his local hospital at 5 days of age with a pale left arm. History was consistent with spontaneous acute ischemia with a cold, atonic, and areflexic whole left arm from the shoulder downward. Capillary refill was less than 4 seconds. There was no axillary or distal palpable pulse on the left upper limb. The left carotid pulse and all other peripheral pulses on both the left and right were all palpable. There was no history of trauma or attempted venipuncture to the left upper arm or neck. Therefore he was transferred to our institution for further investigation and management.
Echocardiography revealed situs solitus, a moderately large perimembanous ventricular septal defect, and mild narrowing of the whole aorta. There was a right aortic arch with an independent origin of the right subclavian artery and a right common carotid artery off the aorta. The left common carotid was well visualized, although there was no visible origin of the left subclavian artery. Left arm duplex revealed patent left subclavian, and axillary and brachiocephalic arteries with radial and ulnar artery hypoplasia.
To treat a potential thromboembolic cause of left arm ischemia, alteplase thrombolysis was commenced and followed with heparin anticoagulation. As there was only a temporary 12-hour improvement of signs, and in view of the need to further delineate the upper limb anatomy, digital subtraction angiography was performed. This revealed the presence of an isolated subclavian artery with an obstruction or thrombus at its base on a ductus diverticulum from the pulmonary artery (Fig 1). Other vessels supplying the left subclavian artery included collateral from the right carotid artery and a tortuous collateral artery coming off the descending aorta. Magnetic resonance imaging revealed a normal intracranial cerebrovascular circulation. Therefore, in view of all of these findings, with the persistence of left arm ischemia, the decision was made for operative management.
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Fig 1. Digital subtraction angiogram with catheterization of the left common carotid artery demonstrating the course of the left subclavian artery and its feeding vessels. (DA/PA = ductus arteriosus/pulmonary artery; LDCA = left deep cervical artery; LSA = left subclavian arterty; LVA = left vertebral artery.)
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After a median sternotomy and standard dissection to the heart and great vessels were performed, cardiopulmonary bypass was instituted with tri-caval cannulation (in view of a persistent left superior vena cava). The left subclavian artery was identified and followed to its direct origin at a closed ductus arteriosus, which did not have any connection to the aorta. The ductal diverticulum was ligated and no thrombus was noted. Therefore the ductal tissue that extended into the proximal subclavian artery was removed, and the artery with a clear lumen was then reimplanted with an end-to-side anastomosis onto the left common carotid (Fig 2). Cardioplegic cardiac arrest was then instituted, and the ventricular septal defect was closed with a patch. The patient was then successfully weaned off of cardiopulmonary bypass, and the chest was closed in a standard manner. Immediately after the surgery the left axillary and brachiocephalic arteries were palpable with good left upper limb capillary refill (<2 seconds).
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Fig 2. (A) Intraoperative view of the native anatomy. (B) Intraoperative view after left subclavian-to-carotid anastomosis. (Ao = aorta; DA = ductus arteriosus; LCA = left common carotid artery; LSA = left subclavian artery; LSVC = persistent left superior vena cava; RCA = right common carotid artery; Tr = trachea.)
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The patient’s signs of left arm ischemia were completely resolved, and a postoperative echocardiogram revealed good closure of his ventricular septal defect. Left arm duplex ultrasound confirmed good flow in his left subclavian, axillary, and brachial arteries, with absent radial and ulnar flows, consistent with known hypoplasia of the latter two. The boy was discharged home on postoperative day 5 with no complication on aspirin. The patient’s left subclavian artery has remained patent on imaging and on clinical examination at 4 months postoperatively, and continued cardiovascular and neurovascular follow-up arrangements have been made. Chromosomal analysis and genetic screening for aortic arch anomalies including 22q deletion to-date have been negative, but this is also under continued follow-up investigation.
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Comment
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The definition of an isolated subclavian artery is where the artery originates from the pulmonary artery through a ductus arteriosus rather than the aorta. This is a rare finding and usually presents itself in neonates as an asymptomatic bystander pathology associated with other symptomatic cardiac anomalies. These associated anomalies, the most common of which is Tetralogy of Fallot, reveal the presence of the isolated subclavian as an incidental finding during cardiac investigations [2]. As with other aortic arch anomalies, these anomalies can have an association with genetic or chromosomal aberrations such as 22q11 deletion [3].
When independent of other symptomatic cardiac anomalies, these associated anomalies are usually clinically silent. However when the patient is a child, adolescent, or even when adulthood is reached, these anomalies have been known to generate pulmonary or subclavian steal phenomena [4]. However, we believe that the signs of left-side upper arm ischemia have not been reported in the literature to date as a presentation of this condition for this age group.
The cause for the onset of ischemia at day 5 may be attributed to the complete closure of a ductus arteriosus at that time, which would then limit the blood flow to subclavian artery and thereby the left upper arm. However this must have been compounded by other factors, because in the experience of pediatric cardiovascular surgery, sacrificing the left subclavian artery only rarely leads to gross left upper limb ischemia. This is exemplified in cases such as subclavian flap aortoplasty for coarctation repair, which in the absence of postoperative subclavian inflow there is ordinarily a sufficient blood flow to the distal arteries in the left arm that is maintained through arterial collaterals. This limited blood flow can prevent ischemia, although it is well known that it has long-term complications [5].
Therefore our rationale for the presentation of ischemia in this case would be the compounding effect of both radial and ulnar hypoplasia within the context of little or no subclavian artery inflow. This was remarkably the case, even when there were collateral vessels into the subclavian, distal to its origin from both an intact vertebral system and left carotid artery and even the aorta. The finding in this case of both radial and ulnar arterial hypoplasia is furthermore, in itself, an extremely rare phenomenon [6], and after successful revascularization of the left subclavian artery to the left carotid artery, we envisage that the prevention of ischemia in the distal left upper arm is likely to be mediated through the remaining arteries in the distal upper arm and hand, such as the anterior interosseous and median arteries [7].
The strong familial element in this case warrants further genetic screening to find a putative aortic arch anomaly gene, although this has not yet been possible in view of the unavailability of various family generations.
Upper arm ischemia in a neonate is rare, and when it presents, typical causes for such a finding in this age group need to be excluded. If these are not present, then other causes need to be considered and investigated with full assessment of the arm, and cardiovascular and cerebrovascular systems. Diagnosis and management of rare cases such as these should then be carried out with broad multidisciplinary input.
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References
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- Hsia TY, Kirkham F, Waldman A, Tsang V. The implications of extensive cerebral vascular dysplasia in surgical repair of coarctation of the aorta and ventricular septal defect J Thorac Cardiov Surg 2001;121:998-1001.[Free Full Text]
- Sun AM, Alhabshan F, Branson H, Freedom RM, Yoo SJ. MRI diagnosis of isolated origin of the left subclavian artery from the left pulmonary artery Pediatr Radiol 2005;35:1259-1262.[Medline]
- Momma K, Matsuoka R, Takao A. Aortic arch anomalies associated with chromosome 22q11 deletion (CATCH 22) Pediatr Cardiol 1999;20:97-102.[Medline]
- McElhinney DB, Silverman NH, Brook MM, Reddy VM, Hanley FL. Rare forms of isolation of the subclavian artery: echocardiographic diagnosis and surgical considerations Cardiol Young 1998;8:344-351.[Medline]
- Wells WJ, Castro LJ. Arm ischemia after subclavian flap angioplasty: repair by carotid-subclavian bypass Ann Thorac Surg 2000;69:1574-1576.[Abstract/Free Full Text]
- Inoue G, Miura T. Arteriographic findings in radial and ulnar deficiencies J Hand Surg [Br] 1991;16:409-412.[Medline]
- Porter CJ, Mellow CG. Anatomically aberrant forearm arteries: an absent radial artery with co-dominant median and ulnar arteries Br J Plast Surg 2001;54:727-728.[Medline]
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Abstract
Introduction
