Aortic Transection in a 10-Year-Old Following a Motor Vehicle Accident

Abstract

Blunt traumatic aortic injury in the pediatric population is exceedingly rare. Few reports or series exist regarding the optimal management of traumatic aortic disruption in the pediatric age group. We report a case of a 10-year-old male with a traumatic aortic transection following a motor vehicle accident.

VASCULAR DISEASE MANAGEMENT 2011;8(8):E141–E143

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Introduction

The leading cause of death in the pediatric population is trauma. Even though traumatic aortic disruption is rare, with an estimated incidence of 0.06% to 7%, it still carries a grim prognosis. The National Pediatric Trauma Registry reports a mortality rate of 50% to 60% in association with this injury. Recent studies, however, have shown an improvement in survival (66–100%).^1,2 Much of the current management of pediatric traumatic aortic disruptions mimics that of adults.

Case Report

A 10-year-old boy was involved in a pedestrian versus motor vehicle accident at unknown speed. The patient sustained injuries to the chest, head, and lower extremities. The patient was initially seen at an outside hospital and after stabilization, he was transferred to our institution. The primary survey noted a 14 on the Glasgow Coma Scale; he was hemodynamically stable with a pulse rate of 120/min and blood pressure of 150/75. Physical examination was remarkable for anisocoria (right pupil 7 mm mildly reactive, left pupil 3 mm reactive); tenderness to left chest, mid-sternum, and epigastrium with a deformity of the right lower extremity. Femoral and distal pulses were present and symmetrical. Review of outside films, including a computed tomography (CT) of the head, did not reveal any evidence of intracranial bleed. Initial serum hemoglobin level was 9.5 g/dl; white blood cell count was 20.4; chest x-ray revealed a widened mediastinum, left apical pleural effusion, and deviation of trachea to right (Figure 1). Focused assessment with sonography for trauma (FAST) exam did not reveal any evidence of intra-abdominal bleed. An x-ray of right lower extremity revealed comminuted fracture of proximal tibial and fibular shaft. A chest CT revealed a mediastinal hematoma, with possible extravasation of contrast in the descending thoracic aorta (Figure 2).

The injury was not felt to be amenable to endovascular treatment and the patient was taken to the operating room for repair of traumatic aortic transection. A left thoracic posterolateral incision was made at the third intercostal space reflecting the scapula cephalad. Cardiopulmonary bypass was initiated via the left femoral artery and vein. Once appropriate exposure was obtained, the left lung was reflected medially, revealing a contained hematoma. The hematoma extended superiorly to the aortic arch and inferiorly to just above the diaphragmatic hiatus. Proximal and distal control was established after careful dissection; the aorta was cross-clamped. The aortic adventitia with hematoma was removed, revealing a complete blowout of the anteriomedial wall of the aorta, inferior to the left subclavian artery (Figure 3). A 16 mm Dacron interposition graft was used to reconstruct the aorta with a cross-clamp time of 46 minutes (Figure 4). The patient tolerated the procedure well. Postoperatively, he underwent surgical repair of his remaining traumatic injuries without issue and was discharged home on postoperative day 11.

Discussion

Traumatic aortic disruption in the pediatric population poses a unique problem for the surgeon and emergency room physicians. Despite its rarity, incidences of 0.06% to 7% are reported in the literature. This injury is associated with significant morbidity and mortality.³ Clinicians should have a high index of suspicion when dealing with multi-organ trauma associated with extensive blunt chest trauma. The initial evaluation and management of pediatric aortic transections parallels that of adults. Initial diagnostic modalities include computed tomography CT scan, angiography, and transesophageal echocardiography (TEE).⁴ CT has gained an increasingly important role in both screening and diagnosis of traumatic aortic injuries, largely replacing conventional angiography as the diagnostic modality of choice. Diagnostic sensitivity for traumatic aortic injuries routinely exceeds 98% and specificity reaches 100% when CT scan is used for direct signs of aortic injury. If mediastinal hematoma alone is included in the institutions diagnostic criteria, false-positive findings are high and may lower the specificity of CT scan.⁵

In those patients with stable aortic injuries, other serious intracranial, abdominal, pelvic or retroperitoneal hemorrhage should be treated prior to thoracotomy. Once stable from all other injuries, pediatric patients with traumatic aortic disruption should proceed immediately for surgery. There is still no consensus in the literature on the most optimal surgical approach to management of traumatic aortic disruptions. Repair of thoracic aortic injuries occurs via primary repair or a graft, using bypass, shunting, or the clamp and sew technique. The prevention of neurological sequela, namely paraplegia, has driven many centers away from the clamp and sew technique. The literature is mixed, but in a large meta-analysis study, when using clamp and sew technique and cross-clamp times exceed 30 minutes without the use of partial or complete heart bypass, there was an increased incidence of postoperative paraplegia.⁶ However, case series in adult patients have shown no difference in postoperative paraplegia when using the clamp and sew technique versus maintaining distal aortic perfusion using partial or complete heart bypass. Clearly, the trend seems to be favoring the use of distal aortic perfusion versus the clamp and sew technique. In certain instances, the clamp and sew technique is preferred. In patients with traumatic brain injury in which procedures must be performed without the use of heparin, the clamp and sew technique can be performed with comparable paraplegia rates when compared to distal aortic perfusion.⁷

Recently, small case series has shown efficacy in using endovascular stent grafts for the treatment of aortic injuries in the pediatric population. Milas et al⁸ showed efficacy in 2 adolescent-aged pediatric patients with traumatic aortic transections and adequate repair postoperatively with no endoleaks. One of the patients has now been followed for over 6 years with an excellent result. There is no migration of the device and the aorta is completely healed in this location. However, given the lack of long-term outcome data even in the adult population, the use of endovascular stent grafts is not widely used in the pediatric population. Several problems are encountered when dealing with the pediatric population. Small-sized vessels make it difficult to gain percutaneous access to deploy large-sized endovascular stents. In fact, one patient in the Milas series required aortic exposure to place the endovascular stent. Stent migration and erosion is also of concern when placing a stent graft in a still growing aorta. Also, distal limb ischemia in small-caliber vessel pediatric patients is a concern. Even more so than adult patients, pediatric traumatic aortic injuries occur in the setting of tremendous force and have multiple associated traumatic injuries.⁹ Many times, unstable patients who require repair, may benefit from the fact that endovascular stent grafting can occur without the use of systemic heparinization and can occur in the same operative setting with other surgical services. Our patient was hemodynamically stable and had no contraindication to systemic anticoagulation and thus was appropriate for open repair. Endovascular stent grafting was not a viable option due to the location of the lesion and the size of the aorta. Lesions in close proximity to the left subclavian artery (LSA) might require coverage of the LSA and outcomes of coverage of the LSA without revascularization are mixed.^10,11 Long-term sequelae of LSA coverage in the pediatric population is not known. As previously stated, aortic and iliac sizes are the major limiting factors to safe, successful deployment of endovascular stent grafts. Aortic size of at least 16 millimeters and iliac size of at least 5 millimeters is needed for deployment of endovascular stent grafts. Our patient’s aortic size was approximately 14 millimeters with an iliac size of 5 millimeters.

References

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From the Loyola University Medical Center, Maywood, Illinois.
The authors report no financial relationships or conflicts of interest regarding the content herein.
Manuscript submitted January 10, 2010, provisional acceptance given May 25, 2011, final version accepted June 1, 2011.
Address for correspondence: Loyola University Medical Center, 2160 S First Ave, Maywood, Illinois, 60153. Email: oalnouri@lumc.edu