Ann Thorac Surg 1997;63:1163-1165
© 1997 The Society of Thoracic Surgeons
Case Report
Isolated Right Subclavian Artery, Interrupted Aortic Arch, and Ventricular Septal Defect
Anvay V. Mulay, MCh,
Kevin G. Watterson, FRACS
Killingbeck Hospital, Leeds, United Kingdom
Accepted for publication November 8, 1996.
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Abstract
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Isolated subclavian artery is extremely rare. The clinical and hemodynamic manifestations depend on the state of ductus arteriosus, pulmonary vascular resistance, and associated intracardiac and extracardiac malformations. We discuss 2 such cases in association with an interrupted aortic arch and ventricular septal defect.
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Introduction
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Isolation of the subclavian artery has been recognized for many years. The term isolation was coined by Stewart and associates in 1964 [1]. They defined isolation as a loss of continuity between one subclavian artery and the aorta with persistent connection to the homolateral pulmonary artery through the patent or nonpatent ductus arteriosus. One autopsy case has been reported with interrupted aortic arch and bilateral ductus-dependent circulation with left aortic arch [2]. We describe 2 cases with this anomaly treated surgically.
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Case Report
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Patient 1
A 7-day-old boy weighing 3.7 kg was referred with a history of cardiovascular collapse, acute renal failure, acidosis, seizures, and hypoglycemia. The patient was transferred, ventilated, and given a prostaglandin infusion. On examination he had reduced peripheral perfusion with absent left radial and femoral pulses. Roentogenogram showed a globular heart, and the lung fields showed areas of focal consolidation. Transthoracic echocardiogram showed a large perimembranous ventricular septal defect with muscular extension, ductus arteriosus, secundum atrial septal defect, a dysplastic aortic valve, and type B interruption.
He proceeded to total correction. The ascending aorta was 6 to 7 mm in diameter and terminated by dividing into the right and left carotid arteries. Anomalous origin of the right subclavian artery was noticed during the dissection of the great vessels. The right subclavian artery was a continuation of the right ductus arteriosus originating at the bifurcation of pulmonary artery (Fig 1
). The interruption of aorta was between the left carotid and left subclavian artery. Cardiopulmonary bypass was established, and under profound hypothermia the interrupted aortic arch was reconstructed by an end-to-side anastomosis. During this period isolated myocardial perfusion was established. The ventricular septal defect was closed and the isolated subclavian artery was ligated.
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Fig 1. . Preoperative anatomy showing type B interruption of aorta, bilateral ducts, and isolated right subclavian artery. (AO = aorta; Desc = descending; LCC = left common carotid artery; LSA = left subclavian artery; Lt = left; MPA = main pulmonary artery; RCC = right common carotid artery; RPA = right pulmonary artery; RSA = right subclavian artery.)
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The immediate postoperative period and recovery were uncomplicated. Four years postoperatively he is asymptomatic, growing well, and receiving no medication.
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Patient 2
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A 2-day-old female infant weighing 3.5 kg was referred because of cardiovascular collapse and acidosis. All the peripheral pulses were weak but equal in volume. At the time of transfer she was ventilated and receiving a prostaglandin infusion. Roentogenogram showed left-sided aortic arch, cardiomegaly, and normal lung fields. Transthoracic echocardiography revealed a large perimembranous ventricular septal defect and type B interruption. The ascending aorta was 6 mm in diameter.
She proceeded to median sternotomy and total correction. The ascending aorta was seen to be very small. It terminated by dividing into right and left carotid arteries. Anomalous origin of right subclavian artery was noticed during the dissection of the great vessels. The right subclavian artery was a continuation of the right ductus arteriosus originating at the bifurcation of the pulmonary artery. The aortic arch was interrupted between the left carotid artery and left subclavian artery (see Fig 1
). Cardiopulmonary bypass was established, and under profound hypothermia, the interrupted aortic arch was reconstructed by an end-to-side anastomosis. During this period isolated myocardial perfusion was established. The ventricular septal defect was closed with a Dacron patch, and the isolated subclavian artery was ligated.
The immediate postoperative course was uneventful, and the child made an uncomplicated postoperative recovery. Six months postoperatively she is growing well and asymptomatic without any medication.
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Comment
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Nath and associates [3] suggested that the term isolation should be confined to the subclavian artery not connecting to the aorta but to the homolateral pulmonary artery. However, there is still no unanimity on describing this condition. The term isolation is often mixed with the conditions where there is a proximal atretic segment of the subclavian artery connected to the aorta or any condition with subclavian steal syndrome. The mechanism responsible for this anomaly has already been discussed and explained on the basis of Edwards' embryologic model of malformation of the aortic arch system [3–5]. The clinical presentation and the echocardiographic and radiologic findings of this very rare condition vary depending upon associated intracardiac and extracardiac malformations and flow through the ducts [6, 7]. Differential cyanosis, "reversed" cyanosis, subclavian steal syndrome, and differences in pulsation and blood pressure have been described in various reports [3, 7, 8].
In both cases described here, there was a large ventricular septal defect. Both the ducts were widely patent with a right-to-left shunt, thus transmitting the flow and the pressure from the hypertensive pulmonary artery to the descending thoracic aorta and to both subclavian arteries. Therefore, except for the cerebral circulation, the whole body circulation was ductus dependent. This explains the lack of difference in blood pressure or pulse volume on the right and left side or in the upper and lower limbs. In a setting of an interrupted aortic arch the only other condition that can clinically manifest like this is where the origins of left and right subclavian arteries are distal to the coarctation (ductus dependent). The only diagnostic investigation done before operation was transthoracic echocardiography. Angiography could well resolve such diagnostic difficulties, but we think it neither necessary nor desirable in such sick neonates. In both the cases diagnosis of an isolated right subclavian artery was made during careful intraoperative dissection.
The ascending aorta was very small (6 to 7 mm in diameter) in both cases, just supplying the head vessels. The very small aorta highlights the two technical difficulties with this condition: difficult arterial cannulation and creating an adequate anastomosis. We adopted an end-to-side anastomosis between the descending thoracic aorta and the arch of aorta (Fig 2). In either case, clinically or echocardiographically there is no sign of recoarctation.
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Fig 2. . Side-to-end anastomosis between the arch of aorta and descending thoracic aorta, divided left duct, and ligated right duct/right subclavian artery.
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The other technical point was what to do with the isolated right subclavian artery. We elected to ligate it. Others have argued that reimplantation should be adopted as the long-term results of ligation of subclavian artery are uncertain because of the possible development of the subclavian steal syndrome [7, 8]. In the setting of a complex procedure, in a sick newborn with a very small ascending aorta and arch, we preferred the pragmatic approach of simple ligation. We believe that to be a safe and the best approach in such a situation.
Both patients are alive and well. They are under regular and careful follow-up. Their growth and development is normal. One is at 4 years postoperatively and the other at 6 months. To date there is no suggestion of a subclavian steal syndrome. However further follow-up is mandatory, as it is possible that it may develop in later years.
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Footnotes
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Address reprint requests to Mr Watterson, Department of Cardiothoracic Surgery, Killingbeck Hospital, York Road, Leeds, LS14 6UQ, UK.
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References
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- Stewart JR, Kincaid OW, Edwards JE. Malformations with left aortic arch (group II). "Isolation" of the right subclavian artery from aorta. In: Stewart JR, ed. An atlas of vascular rings and related malformations of the aortic arch system. 1st ed. Springfield, IL: Charles C. Thomas, 1964:76--9.
- Barger JD, Creasman RW, Edwards JE. Bilateral ductus arteriosus associated with interruption of the aortic arch. Am J Clin Pathol 1954;76:758–61.
- Nath PH, Castaneda-Zuniga W, Zollikofer C, et al. Isolation of subclavian artery. Am J Radiol 1981;137:683–8.[Abstract/Free Full Text]
- Baudet E, Roques XF, Guibaud JP, Laborde N, Choussat A. Isolation of right subclavian artery. Ann Thorac Surg 1992;53:501–3.[Abstract]
- Edwards JE. Anomalies of the derivatives of the aortic arch system. Med Clin North Am 1948;33:925–49.
- Garacia OL, Hernandez FA, Tamer D, Poole C, Gelband H, Castellanos AW. Congenital bilateral subclavian steal. Am J Cardiol 1979;44:101–4.[Medline]
- Methieson JR, Silver SF, Culham JAG. Isolation of the right subclavian artery. Am J Radiol 1988;151:781–2.[Free Full Text]
- Paquet M, Williams RL. Origin of the right subclavian artery from the right pulmonary artery in a newborn with complete transposition of the great arteries. Can J Cardiol 1994;10:932–4.[Medline]
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Abstract
Introduction
