Lower extremity vascular stenting for a post-traumatic pseudoaneurysm in a young trauma patient.

Endovascular treatment of post-traumatic pseudoaneurysms has become a viable, less invasive option when compared to open repair. Due to the relative youth of this technology, studies have yet to be concluded on the long-term patency of stent grafts in this population. For this reason, concern exists with endovascular stent placement in the young trauma patient. In this study, we present a case and review the literature on a post-traumatic pseudoaneurysm of the posterior tibial artery in a 19-year-old man treated with an endovascular stent.

INTRODUCTION

With the emergence of endovascular techniques, there has been a dramatic increase in the number of arterial punctures being performed and a concomitant increase in the incidence of post-surgical pseudoaneurysms. If left untreated, pseudoaneurysms can rupture, partially thrombose and embolize distally, expand and cause adjacent local compression and compartment syndrome.[12] Treatment options vary from ultrasound-guided compression therapy to thrombin injection to open ligation, and now also endovascular techniques. Trauma patients tend to be significantly younger than those traditionally undergoing routine endovascular procedures and typically present with pseudoaneurysms weeks after initial injury.[34] Endovascular treatment of large vessel pseudoaneurysms has been described in the literature.[56] Ahmed et al. describe using a covered stent to successfully repair a brachiocephalic pseudoaneurysm sustained after biopsy during mediastinoscopy. They concluded that stenting is an effective and safe way of repairing a large, nonexpendable artery. Covered stents work by excluding the false lumen, and promoting thrombosis within the pseudoaneurysm while permitting distal flow. This technique has generally been utilized in older patients who may not tolerate an open procedure. The use of stents in the younger population with a post-traumatic pseudoaneurysm represents novel therapy that has yet to be fully investigated.

In this study, we present a case of a post-traumatic, tibioperoneal trunk pseudoaneurysm treated with an endovascular stent, and review the long-term implications of this treatment in a young patient.

CASE REPORT

An otherwise healthy 19-year-old male presented to our Level I Trauma Center after a gunshot to the left lower leg. Physical examination revealed three wounds: two bullet wounds and an open tibial fracture just distal to the gunshot wound tract. The patient's lower extremity motor and sensory examinations were intact with palpable dorsalis pedis (DP) and posterior tibial (PT) arterial pulses. Ankle-brachial indices were normal. The calf was tender to palpation and tense. Imaging confirmed an open, comminuted, and anteriorly displaced fracture of the mid-shaft tibia. CT angiography, obtained due to proximity of the bony fragments to the vasculature and tenseness of the posterior compartments, revealed some contrast extravasation near the distal tibioperoneal trunk but with distal flow through both PT and peroneal arteries.

The patient was taken to the operating room for debridement of the open fracture, intramedullary rod placement and four-compartment fasciotomy. No evidence of hematoma or active bleeding was noted during exploration. The patient returned to the operating room on hospital day numbers two and four for repeat wound debridement and closure of his fasciotomies. The patient was discharged to home on the ninth day of admission.

Eight days after discharge, the patient presented with complaints of persistent left lower extremity pain and new paresthesias. On examination, the patient's calf was enlarged and tender to palpation. He had palpable DP and PT pulses. Dorsiflexion was decreased secondary to pain; his sensory examination was intact.

X-rays revealed no new bony abnormalities and the metal fixation hardware was intact and in good position. A duplex ultrasound ruled out a deep venous thrombosis but was suspicious for a pseudoaneurysm. A CT angiogram confirmed a 4.5 × 6 mm left tibioperoneal trunk pseudoaneurysm, segments of absent flow in the left peroneal artery, and a 1.8 × 3.2 cm fluid collection in the proximal, left calf [Figure 1].

Figure 1

CT angiography shows a 4.5 × 6 mm left posterior tibial artery pseudoaneurysm (thin arrow) and a 1.8 × 3.2 cm hematoma (thick arrow)

The patient was taken to the operating room. The left femoral artery was accessed in an antegrade fashion and an arteriogram confirmed a pseudoaneurysm in the mid-tibioperoneal trunk [Figure 2]. A 5 × 16 × 120 mm covered balloon-expandable iCast stent (Atrium Medical Corporation, Hudson, NH) was deployed from the proximal tibioperoneal trunk to the PT artery excluding the peroneal artery. Completion arteriography demonstrated no further extravasation and patent two-vessel runoff. The calf hematoma was evacuated. Aspirin and clopidogrel therapy were initiated, and the patient was discharged without event.

Figure 2

Intraoperative arteriogram demonstrating the pseudoaneurysm of the left posterior tibial artery (arrow)

DISCUSSION

The above case represents successful endovascular treatment of a post-traumatic, tibial artery pseudoaneurysm. A review of the literature found 11 case reports describing endovascular intervention of infrainguinal pseudoaneurysms following trauma, with symptoms occurring 3 days to 5 years after initial injury. The patients suffered a broad range of injuries from iatrogenic trauma to soldiers post-blast injury [Table 1]. Seven were treated with coil-induced thrombosis of the pseudoaneurysm, while the other four were treated with stent exclusion.[37-16]

Table 1

Literature review of post-traumatic pseudoaneurysms of the lower extremity treated by endovascular intervention

We selected an endovascular approach for our patient's pseudoaneurysm because of the hostile nature of the surrounding tissues. Our endovascular approach avoided dissection of these traumatized tissues, iatrogenic injury to surrounding structures, release of the tamponade on the hematoma and carried less risk of infection.[3412]

Contraindications to covered stent placement include mycotic pseudoaneurysms and narrow or tortuous arteries into which stent placement would not be possible without a large risk of rupture or immediate thrombosis. Complications of stent placement and other endovascular techniques include infection, thrombosis, pseudoaneurysm rupture, and recurrent pseudoaneurysm formation.[17]

Covered stents have also been shown to be very efficacious in the treatment of larger, central pseudoaneurysms.[1819] A recent report by Kubaska et al. showed utility in using an endoprosthesis for traumatic carotid artery pseudoaneurysms. [20] Nitinol-supported expanded PTFE stent grafts have been shown to have primary and secondary 2-year patency rates of 77% and 87% in arteries as far distal as the popliteal artery.[21] Despite these proven successes, controversy arises with the use of endovascular techniques when the smaller arteries distal to the popliteal are involved. Much of the literature written on the use of stents in the distal lower extremity describes its use in the treatment of occlusive disease, in which long-term stent patency rates are notoriously poor because of poor runoff of the diseased vessels and lack of collateral circulation.[22] Spirito et al. described a 74-year-old admitted 2 months after blunt trauma to the leg with CT diagnosis of anterior tibial artery pseudoaneurysm and arteriovenous fistula. Their patient was treated successfully with a PTFE-covered stent and was discharged with initial double antiplatelet therapy, followed by long-term aspirin therapy only. The 1-year follow-up found patent vasculature, without pseudoaneurysm, or arteriovenous fistula.[13]

At present, we are aware of only one other recently published case report describing the use of a covered stent to treat a PT artery pseudoaneurysm.[7] In that report, Joglar et al. describe the case of a 39-year-old male victim of blunt trauma from a low-speed motorcycle accident who presented 3 weeks post-injury with calf pain and swelling and was found by duplex ultrasound examination to have a pseudoaneurysm arising from the right mid-PT artery. Like our patient who presented in a delayed fashion after penetrating trauma to the leg, the diagnosis was confirmed by angiogram and the pseudoaneurysm was then excluded through placement of a covered balloon expandable stent graft in the same fashion as we describe.

One of the major limitations of stent graft use is thrombosis. Oral antithrombotic medications may provide some protection from this, with clopidogrel and aspirin being the mainstays of pharmacologic therapy.[9] Joglar et al. prescribed their patient aspirin and a 12-month course of clopidogrel and noted that at 8-month follow-up, their patient was symptom free, had palpable pedal pulses, an ankle-brachial-index of 1.05 and a patent stent graft as visualized by arterial duplex.[7] We discharged our patient with this same drug regimen, but he lacked health insurance, and we worried that because of this and his age that he would be noncompliant. Despite our realized concern of non-compliance, the patient's initial follow-up ultrasound at 1-month revealed a patent stent with good distal flow and no recurrent pseudoaneurysm.

CONCLUSION

This case report describes one of the first uses of a covered stent for treatment of a PT pseudoaneurysm in a “young” patient. The procedure achieved the immediate goal of excluding the pseudoaneurysm, with preservation of distal flow and without the potential morbidity associated with an open repair in our patient. Follow-up for the patient will consist of ultrasound evaluation of the stent every 3 months for a year, then every year thereafter. The long-term outcome is undetermined, but we hypothesize that good patency rates should be attained due to good arterial inflow to and nondiseased outflow from the stent. Even if the stent thromboses, the leg should not be threatened as a result of our patient's youth and otherwise normal, nondiseased anterior tibial artery.