Blunt Thoracic Aortic Injury

Introduction

Blunt thoracic aortic injuries (BTAIs) are found in only 0.5% of trauma patients who present to the hospital alive; however, the true incidence is much higher because only 20% of patients with a BTAI survive the scene of the accident. Of all deaths at the scene of traffic accidents, 33% are because of BTAI. It is estimated that 14,000 people die annually from BTAI in the United States, making it the second most common cause of death after traumatic brain injury (TBI).

Mechanism of Injury

BTAIs are caused by increased aortic pressures and shear stress in trauma resulting from rapid deceleration. BTAIs most commonly occur as a result of motor vehicle crashes (MVCs; 70%), motorcycle crashes (MCCs; 13%), falls from a height (7%), and pedestrians being struck by a car (7%). Patients who present after a high-speed MVC or MCC, fall from greater than 20 feet, or high-speed pedestrian–car impact are at risk for BTAIs and should undergo screening.

Diagnostic Imaging—CTA Chest

Previously, chest x-ray (CXR) was thought to be the first screening tool for BTAIs, with worrisome findings, such as a widened mediastinum, indistinct aortic knob, apical cap, and left hemothorax, necessitating computed tomographic angiography (CTA) of the chest. However, recent literature has demonstrated that CXR findings are neither sensitive nor specific for BTAI; thus, a normal CXR should not be reassuring.

CTA has become the diagnostic test of choice because of its widespread availability, noninvasiveness with contrast administration via a peripheral intravenous (IV) line, and equivalent sensitivity compared with conventional angiography. High-quality, multidetector computed tomography (CT) scans have become universally available at trauma centers and are employed liberally for the diagnosis of associated injuries in trauma patients. CTA also allows for subsequent planning for endovascular repair and appropriate endograft size selection.