Asian Cardiovasc Thorac Ann 2005;13:369-371
© 2005 Asia Publishing EXchange Ltd
Traumatic Giant Pseudoaneurysm of Innominate Artery
Rajinder S Dhaliwal, MCh,
Suvtesh Luthra, MCh,
Sameer Goyal, MCh,
Sukant Behra, MCh,
Rama Krishna, MCh,
Kanchan Ba, MA
Department of Cardiovascular and Thoracic Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
For reprint information contact: Rajinder S Dhaliwal, MCh Tel: 91 172 271 1070 Fax: 91 172 274 4401 Email: rsdhaliwal{at}glide.net.in, Department of Cardiovascular and Thoracic Surgery, PO Box 1515, P.G.I. Campus, Chandigarh 160012, India.
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ABSTRACT
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A 20-year-old man developed a giant pseudoaneurysm of the innominate artery 5 months after blunt chest trauma, causing severe respiratory distress and superior vena cava compression symptoms. The patient was managed with hypothermia and low flow cardiopulmonary bypass resulting in a successful outcome.
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INTRODUCTION
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Injuries to the branches of the aortic arch are rare and may be caused by blunt, penetrating, blast or iatrogenic trauma.1 The innominate artery is the most frequently injured branch of the aortic arch.2 Few cases of isolated innominate artery injury have been reported in the literature. We report here a successfully managed case of a giant pseudoaneurysm of the innominate artery presenting with severe respiratory distress and superior vena cava compression long after blunt injury to the chest.
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CASE REPORT
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A 20-year-old male patient sustained blunt injury to the right upper chest 5 months previously, as a result of a fall from a moving train. He developed a small swelling (3 x 2 cm) at the medial end of the right clavicle. For 15 days prior to presentation, the patient noticed a sudden increase in the size of the swelling along with increasing respiratory distress. Due to his increasing stridor, the patient was initially seen by an otolaryngologist. The patient was further investigated in another institute and an arch angiography was done showing a large pseudoaneurysm of the innominate artery. He was referred to our center for further management.
On arrival, he was hemodynamically stable, but was having continuing stridor, respiratory distress and gross facial and right upper limb swelling. There was a large (10 x 10 cm), firm, globular swelling, non-pulsatile at the right medial aspect of the neck, extending upwards to the angle of the mandible, the lower extent of which was behind the sternum. Both the right radial and right internal carotid vessels were palpable and were of equal intensity on both sides. The trachea was grossly deviated to the left side. Chest X-Ray showed a large globular swelling in the right upper mediastinum extending into the neck, pushing the trachea to the left, without any rib fracture or hemothorax. Arch angiography performed through a left brachial approach, revealed a tear (7–10 mm) in the anterior wall of the distal innominate artery just proximal to its bifurcation. The dye was leaking from the tear and filling into a large pseudoaneurysm, with patent right subclavian and right common carotid arteries (Figure 1
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While waiting for surgery, the patient developed sudden respiratory arrest for which he was urgently intubated and ventilated. The patient was planned for urgent exploration keeping in mind the need for cardiopulmonary bypass during the procedure. Median sternotomy was contraindicated as the large swelling extended behind the sternum, with the danger of it opening inadvertently during sternotomy. A right anterolateral thoracotomy was done through the 3rd intercostal space. The pericardium was opened anterior to the right phrenic nerve and a vascular control was taken at the origin of the innominate artery. The large swelling was compressing the superior vena cava and was projecting into the right pleural space distorting the anatomy. Distal control of the subclavian and carotid arteries was difficult due to the presence of the large swelling (pseudoaneurysm) in this area. An attempt at distal vascular control caused the swelling to inadvertently rupture, resulting in hemorrhage and hypotension. The bleeding was controlled with direct digital compression and cardiopulmonary bypass was arranged immediately. The incision was extended across the sternum into the left chest via the 3rd intercostal space.
Cardiopulmonary bypass was started after full heparinization, cannulation of the ascending aorta and insertion of a single venous cannula in the right atrium. The patient was cooled to 22°C. At this temperature, the flow rate was reduced to < 300 mL·min–1 and the pseudoaneurysm was opened (Figure 2). There was a large cavity measuring approximately 10 x 10 cm, extending below the superior vena cava, innominate vein and aorta, and extending up to the trachea, which was pushed to the left side. About 500 g of organized clots were evacuated. The rent was identified in the anterior wall of the innominate artery near the bifurcation. It was sutured directly with four pledgetted interrupted mattress sutures of 4/0 prolene. The patient was rewarmed and gradually weaned from cardiopulmonary bypass. The chest was drained with two chest tubes. He was ventilated for 24 hours.
The innominate artery was clamped proximally for about 30 minutes during the rupture of the pseudoaneurysm. The cardiopulmonary bypass time was 2 hours 20 minutes, and low flow was used for 25 minutes. The swelling of the face and both upper limbs gradually settled over a few days. The patient was discharged after 3 weeks in good condition without any neurological deficit or wound complications.
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DISCUSSION
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The innominate artery is the second most common location after the isthmus of the thoracic aorta for deceleration injury to the great vessels.3 The lesion most commonly occurs proximally at, or near, the origin of the innominate artery from the aorta. More distal injuries are less common. The pathologic findings of innominate artery injury from blunt trauma vary. Disruption of the intima with varying degrees of injury to the intima and the media with or without pseudoaneurysm is the most common type of injury. Free bleeding is prevented by the adventitia and mediastinal pleura and by fibrotic reaction. As a result of the weak adventitia, a pseudoaneurysm may eventually rupture.
In the civilian setting, the majority of patients with innominate artery injuries are motor vehicle accident victims, however a few result from crush injuries or falls. Two different types of forces have been proposed to be involved in innominate artery injury. One is compression or entrapment between the sterum or sternoclavicular joint and vertebral column, with displacement of the heart into the left chest, causing tension on the aortic arch, thereby stretching the innominate artery.4 Another is shearing force produced by hyperextension of the neck and rotation of the head, causing longitudinal tension on the innominate artery. Together, both produce maximal stress at the origin of the innominate artery because of the tightly fixed aortic arch and the mobile innominate artery. Thus, the proximal innominate artery is more prone to injury following blunt chest trauma than the distal innominate artery. In our patient, the tear was in the distal part, located in the anterior aspect of the innominate artery just proximal to the bifurcation.
Most innominate artery injuries following blunt trauma are diagnosed in the acute phase, but delayed presentation has been reported in 13.7% of cases.4 Delayed presentations are divided into two categories according to symptoms and/or pathology. One is formation of a thrombus or embolus, and the other is formation of an aneurysm. Traumatic aneurysms are formed by maturation of the pseudoaneurysm, usually a few weeks after injury. Traumatic aneurysm or pseudoaneurysm may not develop symptoms for months or years, but the risks of eventual enlargement, rupture, thrombus formation or embolization are always present. Our patient presented 5 months after the trauma with symptoms of sudden increase in size of the swelling in the neck along with gradually progressing respiratory distress and features of compression of the superior vena cava.
The anatomical location of innominate artery injury at the junction between the neck, chest, and upper extremity complicates surgical exposure. Precise localization of the injury by arteriography is important in operative planning. Details of vascular injury, collateral flow, and distal perfusion can be visualized by a standard angiogram. Computed tomography scan can also be used as a screening tool for intrathoracic vascular injuries. It will detect an intraluminal clot in the aneurysm, distinguish between true and false lumens in dissections, and detect local effects of the hematoma or aneurysm against the adjacent structures. Transesophageal echocardiography and magnetic resonance imaging should not be used in an unstable patient or one with a suspected rupture of the innominate artery.
Median sternotomy is universally used to access the innominate artery. It may be extended to the right neck for distal exposure. The sternoclavicular joint may be dislocated and the proximal portion of the clavicle may be resected for better exposure. In our patient midsternotomy was dangerous as part of the pseudoaneurysm was lying behind the upper half of the sternum, so we used a right anterolateral thoracotomy for exposure. For proximal control of the innominate artery, it may be necessary to open the pericardium, as in our patient. Cardiopulmonary bypass should be used if there is an extension lesion on the aortic arch or a large pseudoaneurysm is present making the distal control of vessels hazardous. Cardiopulmonary bypass should be on standby in distal or middle innominate artery lesions. Temporary innominate artery occlusion during repair infrequently causes cerebral ischemia in healthy young individuals. Patients with decreased carotid pulse, preoperative shock, evidence of cardiac arrest, electroencephalogram changes during operation, or innominate artery stump pressure < 50 mm Hg are candidates for carotid shunting.5 In our patient, we used urgent cardiopulmonary bypass, as distal control of the subclavian and carotid vessels was not possible due to the presence of a large pseudoaneurysm. The incision was extended trans-sternally, which provided adequate exposure for arterial and venous cannulation. The use of cardiopulmonary bypass with hypothermia and low flow may save the patient in a difficult and life-threatening situation, as with our patient.
Repair can consist of lateral arteriography, patch angioplasty, primary end-to-end anastomosis or placement of a prosthetic graft.6 The currently preferred approach for proximal innominate artery injury is the bypass exclusion technique. No shunts, heparin or cardiopulmonary bypass are used for this repair.1,7 Innominate artery ligation should be avoided because of long-term uncertainty of cerebral flow. The mortality and morbidity rate of innominate artery injury from blunt trauma has decreased in the past decade. This may be due to improved surgical techniques, the availability of prosthetic conduits, and the selective use of shunts or cardiopulmonary bypass.
In summary, we report a unique case of post-traumatic pseudoaneurysm arising from the distal innominate artery, presenting 5 months after a blunt chest injury. It was managed by emergency use of cardiopulmonary bypass and hypothermic low flow as a method for cerebral protection and for repair of the tear. All post-traumatic innominate artery aneurysms need to be surgically corrected, to prevent rupture, thrombosis, embolism, and enlargement causing compression on vital structures such as the trachea and superior vena cava.
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ACKNOWLEDGMENTS
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We thank Professsor GD Puri and his resident staff from the Department of Anesthesia for managing this patient very well during surgery and in the postoperative period.
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REFERENCES
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- Mattox KL, Wall MJ. Injury to the thoracic great vessels. In: Feliciane DV, Moore EE, Mattox KL, editors. Trauma, 3rd edn. Stamford, CN: Appleton and Lange, 1996;393–408.
- Rosenberg JM, Bredenberg CE, Marvasti MA, Bucknam C, Conti C, Parker FB Jr. Blunt injuries to the aortic arch vessels. Ann Thorac Surg 1989;48:508–13.[Abstract]
- Graham JM, Feliciano DV, Mattox KL, Beall AC Jr. Innominate vascular injury. J Trauma 1982;22:647–55.[Medline]
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ABSTRACT
INTRODUCTION
