Ann Thorac Surg 2006;81:348-350
© 2006 The Society of Thoracic Surgeons
Case report
Traumatic Partial Avulsion of a Single Right Subclavian Artery from the Aortic Arch and Definitive Repair
Emmanouil I. Kapetanakis, MD
a
,
Pamela Sears-Rogan, MD
b
,
Richard S. Young, MD
c
,
Louis T. Kanda, MD
a
,
Jennifer L. Ellis, MD
a
,
*
a Section of Cardiac Surgery, Department of Surgery, Washington Hospital Center, Washington, DC, USA
b Echocardiography Laboratory, Division of Cardiology, Department of Medicine, Washington Hospital Center, Washington, DC, USA
c Department of Radiology, Washington Hospital Center, Washington, DC, USA
Accepted for publication August 23, 2004.
* Address correspondence to Dr Ellis, Section of Cardiac Surgery, Department of Surgery, Washington Hospital Center, 110 Irving St, NW, Room 1F-1207, Washington, DC 20010–2975.
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Abstract
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Blunt injury to the right subclavian artery is a rare complication of severe deceleration trauma often associated with significant morbidity and mortality. We describe an atypical presentation in a patient who sustained a traumatic avulsion of his right subclavian artery arising off the aortic arch. An interposition graft was used to restore the continuity of the artery to the ascending thoracic aorta.
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Introduction
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A normal right subclavian artery as a primary branch of the aortic arch is an unusual brachiocephalic vessel anatomical anomaly, sparingly reported in the literature [1]. Injuries to the subclavian arteries are rare, accounting for only 1% to 2% of all acute vascular trauma [2]. The vast majority of these stem from penetrating trauma with only 2% to 3% caused by blunt force mechanisms [3]. Mortality and morbidity from injuries to the subclavian artery (range, 4.3% to 14.8%) have been associated with the nature of the injury and the number and type of related injuries [2, 4]. Here we describe an atypical presentation in a patient who sustained a traumatic avulsion of a primary right subclavian artery at the takeoff from the aorta and the subsequent repair performed.
A 51-year-old man was a restrained driver in a single motor vehicle crash. Injuries on admission included, but were not limited to, a right femoral fracture, multiple right rib fractures, dislocation of the right elbow, fracture of the sternum, and a grade II liver laceration. On clinical examination there was a seat belt contusion and erythema over the anterior chest. The patient was hemodynamically stable with no significant blood pressure gradient between his arms. However his chest roentgenogram revealed a nondisplaced, oblique fracture of the mid sternum, a right hemopneumothorax, which was drained, and a widening of the mediastinum. A helical computed tomography scan revealed a hematoma at the superior mediastinum due to disruption of the brachiocephalic trunk without frank extravasation of contrast which was suggestive of a contained rupture (Fig 1). Intraoperative transesophageal echocardiography demonstrated limited visualization of the brachiocephalic trunk with possible disruption at the aortic origin and a minimal pericardial effusion. Cardiopulmonary bypass was established through the femoral vessels. Venting was not utilized because there was no heart distention during the period of cardiopulmonary bypass. Deep hypothermic (20°C) circulatory arrest was instituted for 27 minutes. After entering the chest through a median sternotomy, a judicious superior mediastinum hematoma was apparent. Dissection of the aortic arch area revealed a partial avulsion of an isolated right subclavian artery emerging off the aorta with complete disruption of the intima and media layers, which had retracted 2 to 4 cm from the aortic arch with only the continuing intact adventitia and peri-arterial connective tissues maintaining forward blood flow. Neither the right carotid artery nor any of the other great vessels emerging off the aortic arch sustained any damage (Fig 2A). Proximal hemostatic control was achieved with an aortic cross clamp between the two carotid arteries and a hemostatic clamp placed at the base of the right carotid artery (Fig 2B). A hemostatic clamp placed at the right subclavian provided distal control (Fig 2B). The transection was completed, and definitive repair included the placement of a 12-mm Dacron (C.R. Bard, Haverhill, MA) interposition graft between the aorta and the right subclavian artery (Fig 2C, 2D). Postoperatively the patient was neurovascularly intact and was discharged home after completing treatment for his other various injuries. Complete recovery of function and return to normal activity was reported at the patient's 6-month follow-up.
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Fig 1. Computed tomographic image demonstrating a contained hematoma suggestive of a great vessel injury.
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Comment
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A normally arising isolated right subclavian artery with an atretic brachiocephalic trunk (innominate artery) is an unusual anatomical presentation, sparingly reported in the literature [1]. It probably involves inadequate cranial movement of the seventh segmental artery (future subclavian) during embryological development and failure to join with the carotid to form the right innominate artery [5].
Blunt injury to the subclavian artery usually results from a rapid deceleration force applied to the neck, chest, and upper extremities, usually from motor vehicle accidents or falls [4]. Mechanisms of injury can include avulsion or traction injury from stretch or rotational stress, compression, or contusion from a direct blow, and laceration from fractures of adjacent ribs or clavicle [5]. In the present case, given the anatomical location of the artery, the most plausible mechanism of injury correlates to an innominate artery avulsion whereupon compressive forces on the chest acting in an anteroposterior direction acutely reduce the space between the sternum and the vertebral column displacing the heart posterior and to the left, increasing the curvature of the aortic arch and augmenting tension in its convex portion where the major vessels originate. The hyperextension of the cervical spine adds further stress to the brachiocephalic vessels, leading to an avulsion injury, almost always in the proximal one third of the vessel [6]. This mechanism can be produced with a so-called "seat-belt injury" [6] and can be associated with fractures of the sternum, as in this patient. The arterial intima is the vascular layer most vulnerable to trauma with most lesions caused by blunt trauma presenting there [7]. In more severe vascular contusion cases, such as this one, combined lesions of the media and intima with localized transverse tears or circumferential dissection and elastic retraction of both layers are produced [7]. The adventitia is often left intact maintaining forward blood flow as in our case.
Although there might be a paucity of physical findings, a high index of suspicion needs to be maintained in the setting of severe deceleration injury. Often one can suspect an injury on the basis of clinical findings alone. Presenting symptoms include chest pain, dyspnea, and cough [6]. Pulse inequality and a blood pressure gradient between the arms are also common, although their absence cannot exclude injury because distal perfusion may be maintained through abundant shoulder collateral circulation [4]. Blunt subclavian artery injury is often associated with brachial plexus injury (as much as 50%), and this finding alone should prompt immediate evaluation.
Although widening of the mediastinum or a localized apical lung radio density on chest roentgenogram, as in the present case, is highly suggestive of subclavian artery trauma, aortography is the imaging modality of choice to confirm the diagnosis [6]. However, since trauma centers provide computed tomography on a 24-hour basis, in the setting of acute trauma, computed tomographic scanning is quicker, simpler, cost-effective, and an equally sensitive evaluation of aortic and great vessel injuries with a reported diagnostic accuracy of 88% to 100% [8]. Also in this case, transesophageal echocardiography proved very useful as a portable intraoperative monitoring examination. Transesophageal echocardiography is the only imaging modality that can be performed on very unstable patients, thus it can be very helpful for diagnosis, monitoring, and decision making in acute situations [8].
A full median sternotomy was performed to allow maximum exposure. Given the location of injury, hypothermic cardiopulmonary bypass and circulatory arrest was instituted to ensure adequate proximal hemostatic control of the great vessels and to provide cerebral and distal spinal cord protection. Proximal control of the subclavian artery could not be achieved with tangential clamping, and complete aortic occlusion was used instead. In this case the patient recovered without any neurologic deficits or paraplegia.
Therapeutic approaches for traumatic subclavian artery repair described in the literature include ligation of the artery, end-to-end anastomosis with or without excision of the traumatized vessel parts or insertion of a saphenous vein or prosthetic graft to bridge the defect after retraction of the traumatized vessel segments [4]. Anatomical repair is clearly the most desirable surgical option, especially in older patients in which ligation is not as well tolerated. Whether or not one uses some type of vascular substitute, vein or synthetic prosthetic graft material does not seem to affect outcome [4]. The results from subclavian artery surgery are very satisfactory with morbidity and mortality rates reported at 14.3% and 4.8%, respectively [2, 6]. Improvements in diagnosis, surgical techniques, and cardiopulmonary bypass utilization contribute to this favorable outcome.
In conclusion, we describe the successful surgical management of a patient with traumatic avulsion of a single right subclavian artery. Improved diagnostic and surgical repair principles produced an excellent postoperative outcome and recovery.
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Acknowledgments
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We would like to thank David Hayes for his descriptive illustrations.
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References
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- Strum JT, Dorsey JS, Olson FR, et al. The management of subclavian artery injuries following blunt thoracic trauma Ann Thorac Surg 1984;38:188-191.[Abstract]
- Zelenock GB, Kazmers A, Graham LM, et al. Non-penetrating subclavian artery injuries Arch Surg 1985;120:685-692.[Abstract/Free Full Text]
- Posner MP, Deitrick J, McGrath P, et al. Nonpenetrating vascular injury to the subclavian artery J Vasc Surg 1988;8:611-617.[Medline]
- Hougen TJ. Congenital anomalies of the aortic archIn: Lindsay J, editor. Diseases of the aorta. Philadelphia: Lea & Febiger; 1994. pp. 19-53.
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- Stark P. Traumatic rupture of the aortaa review. CRC Crit Rev Diagn Imag 1984;31:547-550.
- Dolmatch BL, Gray RJ, Horton KM, Rundback JH. Diagnostic imaging of aortic diseaseIn: Lindsay J, editor. Diseases of the aorta. Philadelphia: Lea & Febiger; 1994. pp. 197-250.
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Abstract
Introduction
