CASE REPORT internal mammary artery trauma, blunt

Avulsion of the by Blunt Trauma

Internal Mammary Artery Caused

From the Departments of Surgery* and Radiology/University of Pittsburgh Medical Center, Pittsbu@, Pennsylvania.

Received for publication July 2, 1992. Accepted for publication October 20, 1992.

John Wilkinson*

Timothy D Jacob, MD* John Armitage, MD* Albert Zajko, MD t

Anthony 0 Udekwu, MD* Andrew B Peitzman, MD*

Injury to the subclavian artery or its branches is uncommon after blunt trauma. We report a case of blunt thoracic trauma result- ing in avulsion of the right internal mammary artery from its origin on the subclavian artery. This presented as an atypical mediastinal hematoma in a patient with multiple injuries.

[Wilkinson J, Jacob TD, Armitage J, Zajko A, Udekwu A0, Peitzman AB: Avulsion of the internal mammary artery caused by blunt trauma. Ann frnerg Med November 1993;22:1762-1765.]

INTRODUCTION

The most common arterial injury associated with a widened mediastinum on a chest radiograph after trauma is injury to the thoracic aorta. However, after blunt trauma, injury to the brachiocephalic artery, the subclavian artery, or subclavian branches may occur. This also can present as a widened mediastinum on chest radiograph. Without an adequate work-up, such injuries may be missed during initial evaluation. We report a case of blunt thoracic trauma resulting in avulsion of the right internal mammary artery from its origin on the subclavian artery

CASE REPORT

A 29-year-old man sheared a utility pole in half with his motorcycle. He was found unconscious at the scene of the accident, with systolic blood pressure of 70 mm Hg/palpable; pulse, 110; and grunting respirations with a respiratory rate of 40. intubation was necessary. The patient was resuscitated at an outside hospital where diagnostic peritoneal lavage was negative. A left chest tube was inserted for a pneumothorax. On transfer to our hospital, the patient was found to have facial lacerations, a posterior pharyngeal wall hematoma from the level of the soft palate to the vocal cords, a fractured right fifth rib, an open fracture of the right knee, and closed fractures of the right femoral condyle and acetabulum with posterior dis- location. A widened mediastinum was identified on chest radiograph (Figure 1). With the patient's vital signs stable

NOVEMBER1993 22:11 ANNALS OF EMERGENCY MEDIOINE 1 7 6 2 / 1 3 9

AVULSION Wilkinson et al

at blood pressure of 128/62 mm Hg and pulse of 76, a thoracic aortogram was performed, demonstrating a normal thoracic aorta and proximal great vessels. Computed tomography scans of the head and abdomen were normal.

The patient was taken to the operating room for debride- ment and closure of the knee laceration and placement of a femoral traction pin. He improved gradually and underwent open reduction and internal fixation of the acetabulum on post-trauma day 2. Daily chest radiographs showed gradual resolution of the mediastinal widening. The patient was discharged on post-trauma day 8.

Eleven days later (19 days after the accident), the patient awoke with throbbing pain in his back and right chest.It was relieved by lying on his left side and exacer- bated by lying on his right side. The pain progressed throughout the day and was followed by hoarseness and an episode of hemoptysis.

The patient presented to the emergency department where examination revealed a palpable mass with a thrill and bruit in the right supraclavicular fossa. Radial pulses " were normal, and equal blood pressures were found in both upper extremities. Chest radiograph revealed a large mass in the right superior mediastinum with deviation of the trachea (Figure 2). A thoracic aortogram and selective right subclavian arteriogram were performed and revealed a large false aneurysm filling from the origin of the right internal mammary artery (Figure 3). The patient was taken to the operating room, where a large mass was found arising from the first portion of the subclavian artery, tenting the internal jugular vein, and impinging on the upper lobe of the right lung. After obtaining proximal and distal control, the aneurysm was opened. The internal mammary artery was found to be avulsed from its origin. A 6-ram synthetic graft was interposed in the subclavian artery after ligating the vertebral artery and thyrocervical trunk. The patient did well and was discharged eight days postoperatively.

B I S C U S S r 0 N

Injury to the subclavian artery or its branches is uncom- mon. In the Viet Nam Vascular Registry, less than 1% of penetrating vascular injuries involved the subclavian arter-¢. 1,a Injury to the stibclavian artery resulting from blunt force is even less common. >1o

The subclavian artery is divided into three parts. The first begins at the brachiocephalic artery and ends at the medial border of the anterior scalene muscle. Branches include the vertebral artery, internal mammary artery, and the thyrocervical trunk. The second is behind the anterior

scalene muscle. On the right, the costocervical trunk aris- es from this part of the subclavian artery. However, the left costocervical trunk arises from the first part of the left subclavian artery.

The margins of the third part are defined by the outer border of the anterior scalene muscle and the lateral border of the first rib. The clavicle is superior to the subclavian artery, and the first rib is inferior and partly posterior. 11

The mechanism of subclavian artery injury from blunt trauma forces varies. Crushing chest trauma and first rib fracture are responsible in some cases.5,< 9,10 Compression within the thoracic outlet, between the clavicle and first rib, is a possible mechanism for injury.<r,9,10 Barroy et al mentioned a case of deceleration injury involving avulsion of the right subclavian artery from the brachiocephalic artery, which they attributed to the victim's use of a lap belt and shoulder harness. This resulted in restraint of the left hemithorax but allowed the right hemithorax to continue forward. 4

Injury to the internal mammary artery or another branch of the subclavian artery is even less frequent than that of the subclavian artery itself. Injury to the internal mammary artery by blunt trauma has rarely been reported. 12-14 In a report by Yang et a1,15 hyperextension and rotation of the neck was the cause of a stretching injury of the internal mammary artery, resulting in a pseudoaneurysm. There was also a case report of delayed presentation of a right costocervical trunk pseudoaneurysm after a severe head-on auto accident. 16 The remainder of reported cases involved penetrating trauma, s3,1r

Figure 1. Widened upper mediastinum, right side greater than l@, demonstrated on admission chest radiograph

Figure 2. Large right-sided mediastinal mass seen on readmission chest radiograph

1 4 0 / 1 7 6 3 ANNALS 0FEMEFI6ENCYMEDICINE 22:11 NOVEMBER1993

: A V U L S I O N P Wilhinson et al

Injury of the internal mammary artery after blunt trauma may be caused by several mechanisms. In association with a rib, clavicular, or sternal fracture, displaced bone may cause direct injury to the vessel. 13 In our patient, the inertial and shearing forces involved in the accident worked to create an extreme stretching injury with avul- sion of the internal mammary artery at its origin from the subclavian artery.

Perhaps the most important finding in patients with disruption of the subclavian artery or its branches is widened mediastinum on chest radiograph. 1-3,7,12,13,1 r The acute false aneurysm from internal mammary artery avulsion in this patient may have been missed on his first angiogram because of thrombus occluding the subclavian artery injury at the time of the initial angiogram. This is suggested by the resolution of his superior mediastinal hematoma during his first week in the hospital. However, this rare arterial injury should be detected at initial angiogram, which includes views of the first and second parts of the subclavian artery. This may be particularly important in patients with atypical mediastinal hematomas.

Other findings on chest radiograph that may warrant evaluation for great vessel injury include first rib fracture or clavicular fracture, as mentioned above. 1,<9,10 These patients generally have multisystem injury, as significant associated injuries occur in more than 50% of patients

Figure 3. (A) Large false aneuusm inferior to tl~e right subclavian artery demonstrated on thoracic aortogram. Note narrowing of the proximal right subclavian artery. The right internal mammary artery is patent. The aortic arch is normal. (B) False aneurysm arises at the origin of the right internal mammary artery on selective subclavian arteriogram.

with subclavian artery injury9, lo Diminished distal pulses or blood pressure in the affected arm also was noted in some cases. 1,2,4,5,9,~0,16,18 Neurologic findings included brachial plexus palsy,1 recurrent laryngeal nerve paralysis, and Homer's syndrome. 15,1s Chest pa!n was a prominent feature in several cases.2,6,12,18 Several patients with an associated aneurysm had pulsatile masses and bruits in the area of the subclavian artery.4,6,16, is Hemoptysis also has occurred as a result of erosion of the aneurysm into the lung parenchyma. ~9 With a large aneurysm, compres- sion of the trachea with dyspnea may result.2,6, is

SUMMARY

The finding of a widened mediastinum on chest radiograph in a victim of blunt trauma necessitates further evaluation, generally a thoracic aortogram to exclude injury to the thoracic aorta. We report the case of a 29-year-old man who had a normal thoracic aortogram on admission to the hospital in evaluation of his widened mediastinum but presented 19 days after his accident with a large media-stinal hematoma on chest radiograph. This was found to be a large false aneurysm of the first portion of the subclavian artery where the internal mammary artery had been avulsed. The patient had an uneventful peri- operative course.

During evaluation of the patient with a widened mediastinum and normal thoracic aorta, injury to the great vessels and their branches must be considered. With an atypical mediastinal hematoma, selective angiography in addition to thoracic ac?rtography should be pursued to define the arterial injury.

REFERENCES 1. Sturm JT, Cicero J J: The clinical diagnosis of ruptured subclavian artery following blunt thoracic trau me. Ann Emerg Med 1983;12:45-47.

2. Solheim K: Closed subclavian artery injuries. Scand J Thorac Cardiovasc Surg 1981;15:283-287.

3. Vix VA, Donahoo JS: Subclavian artery aneurysm due to blunt chest trauma. Am Surg 1978;36:561-562.

4. Barroy JP, Gelin M, Van Stratum M, et al: Avulsien of the right main stem bronchus associated to a false aneurysm of the right subclavian artery after closed chest trauma. Thorax 1979;34:684- 685.

5. Prior AL: Two traumatic i ntrathoracic aneurysms in one patient. Injury 1980;11:248-250.

6. OIinde A J: Traumatic subclavian-axillary artew aneurysm (letter). J Vasc Surg 1990;11:848-849.

7. Baldwin JC, Oyer PE, Guthaner DF, et al: Combined azygous vein and subclavian artery injury in blunt chest trauma. J Trauma 1984;24:I704 71.

8. Echave V, Glock Y, Herreros J: Los faux anevrysmes de la sous-claviere. Can J Surg 1981 ;24:651-653.

9. Posner MP, Deitrick J, McGrath P, et al: Nonpenetrating vascular injury to the subclavian artery. J Vasc Surg 1988;8:611-617.

10. ZeLeneck GB, Kazmers A, Graham LM, et al: Nonpenetrating subclavian artery injuries. Arch Surg 1985;120:685-692.

NOVEMBER1993_ 22:11 ANNALS OF EMERBENCY MEDICINE 1 7 6 4 / 1 4 1

A V U L S I O N Wilkinson et aZ

11. Angiology, in Williams PL, Warwick R, Dyson M, et al (ads): gray's Anatomy. ad 37. New York, Churchill Livingstone, 1989, p 74£-756.

12. Smith De, Senac MO, Bailey LL: Embolotherapy of a ruptured internal mammary artery secondary to blunt chest trauma. J Trauma 1982;22:333-335.

13. Mehlala ML, Vanker EA, Ballaram RS: Internal mammary artery haematoma. SAfrJSurg 1989;27:136-138.

14. Schroeder J, Hissen W: Die Behandlung einer traumatischen Blutung aus einer A. mammaria interna durch Embolisation. Fortschr Roentgenstr 1979;131:103-104.

15. Yang P J, Seeger JF, Carmedy RF, et al: Homer's syndrome secondary to traumatic pseudaaneurysms. AJNR 1986;7:913-915.

16. Mintz S, Nelson EW: Delayed cestocervical trunk aneurysm. J Trauma 1982;22:519429.

17. Curley SA, Demarest GB, Hauswald M: Pericardial tamponade and hemothorax after penetrating injury to the internal mammary artery. J Trauma 1987;27:£57-958.

18. Aseem WM, Ghafar AW: Late development of subclavian false aneurysm (letter). Arch Surg 1974;109:844.

19. Mii S, lenaga S, Motohiro A: An unusual symptom of subclavian artery aneurysm: Hemoptysis (letter). J Vasc Surg 1991;14:243-245.

Address for reprints:

Andrew B Peitzman, MD

497 Scaife Hall

Department of Surgery

University of Pittsburgh School of Medicine

Pittsburgh, Pennsylvania 15261

1 4 2 / 1 7 6 5 ANNALS OF EMERGENCY MEDIClNE 22:11 NOVEMBER1993