Blunt Aortic Injury and Anatomy
The descending aorta is fixed to the chest wall, whereas the heart and great vessels are relatively mobile. Traditional views have held that sudden deceleration causes a tear at the junction between the fixed and mobile portions of the aorta, usually near the isthmus. However, injury may also occur to the ascending aorta, the distal descending thoracic aorta, or the abdominal aorta. Many blunt aortic injuries probably involve a combination of forces, including stretching, shearing, torsion, and a “waterhammer” effect which involves simultaneous occlusion of the aorta and a sudden elevation in blood pressure. The aorta may also become entrapped between the anterior chest and the vertebral column, in a so-called “osseous pinch” effect to cause blunt injury.
What is the diagnostic test of choice for blunt aortic injury?
Helical computed tomography (CT) is now the diagnostic test of choice for blunt aortic injury. Helical CT of the thorax is more sensitive for blunt aortic injury than angiography and is estimated to have a sensitivity of 100%, as compared with 92% for angiography. Other options for the diagnosis of blunt aortic injury include transesophageal echocardiography, intravascular ultrasonography, and magnetic resonance imaging.
Perioperative Management of Blunt Aortic Injury
Once the diagnosis of blunt aortic injury is made, treatment and surgical repair must be properly timed. Several studies have demonstrated the relative safety of a delayed approach, particularly if there are substantial coinjuries, using a regimen of beta-blockers and antihypertensive agents to decrease the shear force on the aortic wall. Fabian and colleagues performed a prospective study (Ann Surg, 1998) using beta blockers with and without vasodilators to maintain a systolic blood pressure of approximately 100 mm Hg (or 110 mm to 120 mm Hg in older patients) and a pulse rate of under 100 beats per minute in selected patients with blunt aortic injury and a coexisting head injury, pulmonary injury, or cardiac insufficiency. In this study, no patient had an aortic rupture while awaiting repair.
New England Journal of Medicine - Vol. 359, No. 16, October 16, 2008