Challenges in Appropriate Sizing of Thoracic Endografts for Thoracic Aortic Transection

Abstract

<h3>Introduction and Objective</h3> Blunt aortic injury (BAI) is the second leading cause of death from motor vehicle collisions. Implementation of Thoracic Endovascular Aortic Repair (TEVAR) for aortic transection has resulted in decreased morbidity and mortality. Accurate sizing of the graft depends on appropriate measurement of the Aortic Lumen Diameter (ALD). The aorta of the trauma patient is often healthier and smaller, and oversizing should be conservative. While trauma patients with high impact injury might be under resuscitated on presentation and with possible hemodynamic abnormalities, the data on the effect of those findings on ALD measurements is limited. We aim to assess the effect of hemodynamic instability on the reliability of admission CT scan measurements for accurate graft sizing in patients with BAI. <h3>Method</h3> This is a retrospective review of 10 consecutive patients presenting with BAI and undergoing TEVAR. Demographic data and repeat imaging studies as well as intraoperative findings were reviewed. All measurements were performed in an axial plane with the shortest diameter at the origin of the left subclavian artery as well at 10 and 20 cm distal to left subclavian origin. <h3>Results</h3> Average age of presentation was 33.2 years (16-63). 80% were males. Mechanism of injury was motor vehicle collision in 90% of the patients. 50% had a systolic blood pressure (SBP) under 90 or a shock index (SI) above 1 in the trauma bay and required blood products. Average time from presentation to CT was 60 minutes (13-123). One patient had persistently elevated SI in the CT scanner. Aortic injury was distal to the left subclavian artery in all patients. Injury grade was grade two (n=2) or grade three (n=8). 90% of patients had associated thoracic injury (Hemothorax n=7, mediastinal hematoma n=5, rib fractures n=4). All patients had associated extra thoracic injuries (long bone fracture n=2, solid organ injury n=2, combined n=6). None had intracranial hemorrhage. Average diameter of the thoracic aorta at the left subclavian artery ostium was 22.4mm (19.0-31.1). 70% of patients had either a repeat CT of the chest (n=4) or intraoperative intravascular ultrasound (n=3) before deployment of the graft. Average ALD difference was 1.2mm (0.0-4.2). The only patient with ALD difference significant enough to affect graft size choice was the patient with persistently elevated SI. Mean operative time was 79 minutes (42-138). Conformable GORE® TAG® was used in 8 patients while Medtronic Valiant™ was used in two patients. All patients had follow up CT imaging. One patient had an endoleak that resolved overtime. Average follow up was 1 year (14-958 days). <h3>Conclusion</h3> Patients with BAI tend to present with long bone fracture and solid organ injury which can result in blood loss and hemodynamic instability. Size discrepancy between admission CT scan and repeat imaging significant enough to affect graft choice was only seen in one out of seven patients. This patient also happened to have persistently elevated SI. We recommend incorporating information of the patient's hemodynamic status during imaging studies, utilized for graft sizing, when repeat imaging is not feasible.