Management of Pediatric Aortic Pseudoaneurysm Due to Penetrating Trauma

Abstract

Due to the increasing frequency of pediatric penetrating trauma, pediatric surgeons need to be prepared to evaluate and manage complex penetrating injuries. In this report, we discuss the endovascular management of a traumatic aortic pseudoaneurym and subsequent bullet retrieval following penetrating chest trauma in a child. The key to successful management included multidisciplinary decision making and use of an expandable covered stent generally used for management of aortic coarctation.

Penetrating trauma is now the leading cause of death in children. ¹ Due to its increasing frequency, pediatric surgeons need to be prepared to evaluate and manage complex penetrating trauma, such as aortic pseudoaneurysms due to penetrating chest trauma. Previous reports have described the successful management of traumatic aortic pseudoaneurysms with endovascular stents. ² In this case, we add to this literature by describing the rare case of pediatric traumatic aortic pseudoaneurysm managed with a thoracic endovascular covered stent and subsequent bullet retrieval.

A 9-year-old male presented with a gunshot wound to his left chest. On initial evaluation, he was asymptomatic with an anterior chest entry wound without an associated exit wound. Initial chest radiograph identified a large bullet within the mediastinum with an associated small left hemopneumothorax. A left chest thoracostomy tube was placed with initial bloody output <100 mL. Given the patient’s hemodynamic stability, computed tomography (CT) of the chest was performed and the bullet was identified within the posterior mediastinum adjacent to the descending aorta, left pulmonary vein, and atrium (Figure 1A). Due to lack of direct injury to the major mediastinal vessels, the patient was managed non-operatively and admitted to intensive care for observation and blood pressure control. Given the bullet metallic artifact and inability to sufficiently exclude an aortic injury with CT, an aortogram was performed on hospital day 2, which showed a normal contour of the aorta without any underlying luminal irregularities. He was discharged on hospital day 3 with plans for surveillance chest CT angiogram 1 week after discharge. The surveillance scan showed clear interval development of a descending aortic pseudoaneurysm adjacent to the bullet (Figure 1B). The maximal luminal caliber was 20 mm × 17 mm, compared to 14-15 mm the week prior.

Figure 1.

Sagittal view of CT chest (A) at initial presentation, (B) 8 days after injury (with associated aortic pseudoaneurysm), (C) 1 month after endovascular stent placement, and (D) 2 years after endovascular stent placement.

The patient remained asymptomatic but was readmitted to the intensive care unit for blood pressure control and multidisciplinary management (ie, pediatric trauma surgery, vascular surgery, congenital cardiac surgery, and pediatric cardiology). Open aortic resection was deferred due to the need for cardiopulmonary bypass and inherent risks. When exploring endovascular options, a standard, fixed diameter thoracic aortic stent graft was thought to be too long (covering vital spinal arteries and risking paralysis). Additionally, given its fixed diameter, it posed the risk of future stricture with natural aortic growth. Therefore, we decided to utilize an expandable stent generally used by pediatric cardiologists for stricture management following aortic coarctation repair. The child was taken to the cardiac catheterization lab by pediatric cardiology and vascular surgery for placement of 8 Zig 3.9 mounted covered CP balloon expandable stent graft (Braun) on a 16 × 4 BIB balloon®. Percutaneous right common femoral artery access was obtained under ultrasound guidance, and the 5Fr access sheath was exchanged for a 12Fr sheath. The stent was successfully deployed, then carefully post dilated to 16 × 39 mm with excellent proximal and distal wall apposition (Figure 2). After the procedure, the patient developed asymptomatic occlusive right iliac artery thrombosis and nonocclusive right iliac vein thrombus, which was likely due to large caliber sheath required for stent implantation. He was started on therapeutic anticoagulation with Lovenox. He was discharged home on postoperative day 4 with 3 months of outpatient anticoagulation. Three-month follow-up ultrasound demonstrated resolution of the venous thrombosis, persistent iliac artery thrombosis with collateral flow, and no symptoms of leg ischemia.

Figure 2.

Angiogram during endovascular procedure: (A) pre-stent deployment and (B) post-stent deployment.

With further multidisciplinary discussion, there was concern about bullet erosion into the aorta or atrium. Therefore, the decision was made to remove it. Six weeks post-stent placement, an elective operation was planned for bullet retrieval. This time frame was chosen to avoid significant scarring and to allow the aortic injury to heal. A thoracoscopic approach was utilized (with cardiac surgery backup) to successfully extract the bullet. The bullet was found within a small abscess cavity and was gently retrieved. There were no complications. Following this operation, the child recovered well and was discharged home on postoperative day 4 with a 7-day course of antibiotics. Serial surveillance CT scan at 1 month (Figure 1C), 6 months, and 2 years (Figure 1D) showed a widely patent covered stent.

This is a unique case of a delayed thoracic aortic pseudoaneurysm following penetrating chest trauma in a child. There are some key learning points from this case. First, the pseudoaneurysm developed within a week after injury despite initial imaging showing no injury to the thoracic aorta; thus, early planned surveillance was important. Second, the expandable covered stent generally used for aortic coarctation was an appropriate stent choice. This stent graft has the unique advantage of being further balloon expandable, if needed, as the child grows. Use of this type of stent has been reported in the pediatric literature, but always for blunt aortic injury. ² Centers involved in the multicenter coarctation of the aorta stent trial have reported placement of these stents for 6 pediatric patients with generally good long-term outcomes. ² In median follow-up of 2 years, there was stent fracture in 1 patient who had received overlapping stents and a recurrent aneurysm in 1 patient that was managed with a second stent with good result. ² As far as we are aware, this is the first reported case of use of this stent for aortic pseudoaneurysm secondary to penetrating trauma. The third interesting learning point for this case is the decision regarding bullet retrieval. Non-operative management for penetrating trauma is supported when there is no acute injury; however, there is very little guidance in the literature about chest trauma. ³ The risk of bullet erosion is possible, and the risk of lead poisoning from retained bullets is an increasing concern. ⁴ The decision was made in this case to remove the bullet. Given the stent supporting the aortic wall adjacent to the bullet, the risk of aortic wall injury while pulling on the bullet was reduced. The retrieval went well. However, leaving the bullet in place could also have been considered but would have required serial surveillance imaging and echocardiograms for possible erosion or migration.