Delayed Presentation of a Post-Traumatic Subclavian Pseudoaneurysm

Case Study and Review

Submitted on Fri, 09/05/2008 - 16:36
Authors

<sup>1</sup>Divyan Pancharatnam, DMRD, <sup>1</sup>Shyamkumar Nidugala Keshava, DNB, FRCR, FRANZCR, <sup>1</sup>George Koshy Chiramel, DMRD, <sup>2</sup>Sukriya Nayak, MS, <sup>2</sup>Sunil Agarwal, MS

<b>Introduction</b>
In patients with polytrauma, injuries are treated after they are prioritized based on their severity. Some injuries, if managed conservatively, may result in delayed complications. We present a patient with a fractured clavicle who presented with a related complication 2 months later. The management of the case is also discussed.

<b>Case Study </b>
<i>A 40-year-old male was brought to the emergency services department with multiple injuries sustained during a fall from a two-wheeler while under the influence of alcohol.

His sensorium was initally obtunded, but gradually improved over the next few hours. His pupils were equal and reactive, but there was bleeding from his ears and nostrils. He had an undisplaced fracture of the middle third of the clavicle on the right side, but had no obvious motor weakness.

There was a major head injury on the left side. A computed tomography scan revealed a large subdural hematoma over the left temporoparietal region, causing mass effect and subarachnoid bleed in the sylvian fissures and basal cisterns bilaterally. A craniotomy was done to evacuate the subdural hematoma. He subsequently improved and was discharged with advice to consult orthopedics for further management of the fractured clavicle.

Two months later, he returned with marked weakness of the right upper limb and a large pulsatile swelling in the right supraclavicular region. The brachial and radial pulses of the affected limb were markedly reduced. Blood pressure measurements in the left and right upper limbs were 130/86 mm Hg and 60 mmHg (systolic), respectively.

A color Doppler study showed a large pseudoaneurysm arising from the right subclavian artery. The lumen of the subclavian artery, though of reduced caliber, was patent. Blood flow was reduced in the brachial and radial arteries of the affected limb.

The patient was started on 150 mg of aspirin and 70 mg of clopidogrel on the day of the angiogram. During the angiogram, 5,000 IU of heparin was given as a bolus intravenously.

An angiogram of the right subclavian artery was performed using the right femoral artery for access. A large pseudoaneurysm with a 4 mm neck was seen arising from the right subclavian artery at the junction of its middle and distal third. There was inferior displacement and narrowing of the subclavian artery, as well as splaying of the surrounding branches. No thrombus was present within the artery. The caliber of the contralateral subclavian artery, as measured using ultrasound, was found to be 6 mm.

A covered stent graft (<i>Hemobahn, W.L. Gore and Associates, Flagstaff, Arizona</i>), measuring 7 mm x 5 cm, was deployed in the subclavian artery across the neck of the pseudoaneurysm. However, a postdeployment angiogram showed a large thrombus within the distal subclavian artery.

A decision was made to lyse the thrombus using a very small dose of urokinase (150,000 units over 15 minutes). The thrombus was thus cleared successfully, but the emboli flowed downstream and obstructed the distal brachial artery. Further infusion of urokinase was not given because of the recent history of intracranial bleed.

The patient was then sent for surgical embolectomy. Under local anesthesia, a cutdown was done in the antecubital fossa, and embolectomy was performed using a Fogarty balloon. Good arterial flow was established.

A subsequent Doppler study showed normal flow in the right brachial, radial and ulnar arteries. There was total thrombosis of the subclavian pseudoaneurysm.

Reassessment of the patient in the outpatient department 3 months later revealed that there was a reduction in the supraclavicular swelling, along with significant improvement of the neurological status and function of the right upper limb.</i>

<b>Discussion</b>
Pseudoaneurysms of the subclavian artery are rare and usually occur immediately after a major trauma or iatrogenic injury. This patient presented 2 months after the initial injury, probably because of slow leakage of blood from the injured subclavian artery. The complications associated with an untreated pseudoaneurysm are related to continuous expansion and may result in rupture, arterial thrombosis, compression of the adjacent neurovascular structures and erosion through the skin surface, leading to an external bleed.

Subclavian aneurysms are technically difficult to treat by using surgery.<sup>1</sup> Hence, an endovascular approach has become the treatment of choice, being a less invasive technique, resulting in a shorter procedure time and reduced blood loss. This plays an important role in patients who are in a critical state or who are suffering from other comorbidities.

An endovascular approach involves the deployment of a covered stent graft to exclude the neck of the pseudoaneurysm, promoting thrombosis within it.<sup>2</sup> There are many reports of successful treatment of subclavian pseudoaneurysms using a stent graft, sometimes in combination with coil embolization.<sup>3</sup>

Thrombosis of the parent vessel is a rare complication of this procedure.<sup>4</sup> The risk may be minimized by prior oral antiplatelet medications. Aspirin and clopidogrel have a synergistic effect on platelet antiaggregation, on antithrombotic activity, and prevention of myointimal proliferation and restenosis.<sup>5,6</sup>

Thrombus formation of the subclavian artery could have either occured in situ or could have gotten dislodged from the pseudoaneurysm during manipulation. This is best treated with a local infusion of a thrombolytic agent (urokinase). If thrombolysis is contraindicated, surgical thrombectomy could be considered.

In conclusion, endovascular repair of pseudoaneurysms using a covered stent graft is a good technique yielding satisfactory results, and is a preferred option in the treatment of a posttraumatic subclavian artery pseudoaneurysm. Thrombosis at the site of intervention should be kept in mind as a potential complication. Adequate premedication with antiplatelet drugs could reduce the possibility of thrombosis.