Imaging of acute traumatic injuries of the thoracic aorta

Abstract

Epidemiology and biomechanicsBlunt injuries of the thoracic aorta are met in 0.5±2 % of chest trauma patients admitted in emergency rooms alive [1,2]. Aortic lesions represent the most lethal condition among chest injuries and are responsible for up to 40 % of fatalities occurring in traffic accidents [2,3]. Head-on and lateral motor vehicle accidents at speeds superior to 50 km/h, or associated with substantial car deformity, are the main cause (76 %) of blunt traumatic aortic injuries, followed by falls from heights ± usually exceeding 3 m ± and crush injuries [4,5,6,7].Four mechanisms are hypothesized to explain blunt lesions to the thoracic aorta [8,9]. Sudden antero-posterior or lateral deceleration superior to 80 g induces anterior cardiac displacement, leading to shearing forces, and sometimes rupture, at the aortic isthmic level [3,8]. Rapid vertical deceleration occurring in falls from height results in aortic arch compression against the anterior thoracic cage. Aortic injuries with such biomechanics are thus located on the ascending aorta [10]. The ªwater-hammer effectº relates to a low thoracic or abdominal compression. The resultant sudden increase of the intra-aortic pressure may be responsible for ascending aortic injuries immediately above the aortic valve. A pressure peak of 80±350 kPa (600±2500 mmHg) is required to rupture a normal aorta [5]. Finally, the ªos-seous pinchº hypothesis assumes a compression of the heart and the aorta between the sternum and vertebral column, for instance, under a violent frontal impact against the steering wheel. The resultant left posterior displacement of the heart generates an aortic torsion, which may result in a traumatic aortic lesion, sometimes associated with thoracic vertebral fractures [11]. Eur. Radiol. (2002) Abstract Blunt traumatic aortic injuries are a major concern in the settings of high-speed deceleration accidents, since they are associated with a very high mortality rate; however, with prompt diagnosis and surgery, 70 % of the patients with a blunt aortic lesion who reach the hospital alive will survive. This statement challenges the emergency radiologist in charge to evaluate the admission radiological survey in a severe chest trauma patient. With a 95 % negative predictive value for the identification of blunt traumatic aortic lesions, plain chest film represents an adequate screening test. If aortography remains the gold standard, it tends, at least in hemodynamically stable trauma patients, to be replaced by spiral-CT angiography (SCTA), which demonstrates a 96.2 % sensitivity, a 99.8 % specificity, and a 99.7 % accuracy. In unstable patients, trans-esophageal echography (TEE) plays a major diagnostic role. Knowledge of advantages and pitfalls of these imaging techniques, as reviewed in this article, will help the emergency radiologist to choose the appropriate algorithm in the diagnosis of traumatic aortic injury, for each trauma patient.Keywords Wounds and injuriesT horacic injuries´Aortic ruptureD iagnostic imaging´X-ray CTÉ mergency tr...

Vascular Trauma: New Directions in Screening, Diagnosis and Management

“…Of blunt causes motor vehicle crashes are the most common followed by falls from height and pedestrians struck by vehicles (Asensio, et al, 2001b;Bertrand, et al, 2008;Mirvis & Shanmuganathan. 2007;Wintermark, et al, 2002). Unlike extremity vascular injury where bleeding, hematomas, pulsations, thrills, bruits, and in some cases the vessels themselves are easily examined clinically, outside of hypotension, there are few clinical signs of truncal vascular injury.…”

“…2004). Of patients surviving to evaluation TAI is present in approximately 0.3-2.8% of patients (Arthurs, et al, 2009;Bertrand, et al, 2008;Fitzharris, et al, 2004;Ungar, et al, 2006;Wintermark, et al, 2002). Detection of these few patients has long been a subject of debate.…”

“…Multi-detector helical scanners now have the ability to acquire more data in less time (20-35 seconds), with improved definition, and MIP and 3-dimensional reconstruction has allowed even greater anatomical accuracy. Modern series reliably report sensitivity between 95-100% (Bruckner, et al, 2006;Dyer, et al, 2000;Exadaktylos, et al, 2005;Fisher, et al, 1994;Raptopoulos, et al, 1992;Wintermark, et al, 2002). Specificity, initially a drawback ranging from 83-86% (Fabian, et al, 1998;Raptopoulos, et al, 1992), has improved with modern technology as well and now ranges between 94-99.8% (Mirvis & Shanmuganathan.…”

“…Specificity, initially a drawback ranging from 83-86% (Fabian, et al, 1998;Raptopoulos, et al, 1992), has improved with modern technology as well and now ranges between 94-99.8% (Mirvis & Shanmuganathan. 2007;Wintermark, et al, 2002;Wong, et al, 2004). These advances have come at the price of higher radiation doses due to the greater number of detectors.…”

“…Additionally, IVUS requires arterial puncture with the attendant risk of access site complications of hematoma, fistula, pseudoaneurysm, and dissection. The risks of such local complications may be greater for IVUS than for diagnostic angiography as the sheath size required to accommodate the ultrasound probe is larger (7-8Fr) than that typically needed for diagnostic angiography Wintermark, et al, 2002). Despite the benefits of TEE and IVUS they are used in very few cases (1-4%), and appear to be decreasing in frequency, from 11.9% to 1% (Demetriades, et al, 2008b;Melton, et al, 2004).…”