With a history of any deceleration injury, there should be a suspicion for possible acute aortic transection. Symptoms on arrival at the emergency room in a conscious patient range from nonspecific complaints to those of chest pain, intrascapular pain, hoarseness, dyspnea, dysphasia, and frank paralysis. Physical examination findings include rib fractures, sternal fractures, and even imprints of the steering wheel on the chest. The cervical and thoracic spines are also vulnerable, and these should be carefully examined. Hypertension in the arms, so-called coarctation syndrome, has been reported. It is important to carefully examine the pulses in the upper and lower extremities and check for any differences. A baseline neurologic examination is extremely important in these patients because paraplegia may be present preoperatively and may be due to other causes such as spinal fractures and dislocations.

In the era of liberal CT scanning, chest roentogram has a less important role, but diligent examination is still warranted,
especially in patients with otherwise underwhelming presentation. An initial chest radiograph should be obtained as soon as the patient’s cervical spine is cleared. An upright posteroanterior (PA) film is desirable; however, the most upright anterior-posterior (AP) film possible is the best alternative. Supine chest radiographs usually reveal a widened mediastinum. Any abnormality seen in the mediastinum on an upright PA chest film should raise the suspicion for aortic transection and prompt further investigation. Various specific radiographic findings associated with aortic transection include mediastinal widening, obscurity of the aortic knob, obliteration of the AP window, tracheal deviation, depression of the left mainstem bronchus, widening of the paravertebral stripe, deviation of the esophagus (seen most commonly as deviation of the nasogastric tube), and a left hemothorax. Fractures of the first rib and/or scapula should raise the suspicion of an aortic injury due to the extreme force required to fracture these bones. A history of a deceleration injury in conjunction with an abnormal mediastinum seen on the chest radiograph should prompt further investigation.

CTA has replaced arch angiography as the modality of choice in investigating blunt aortic injury (Fig. 62.1). Magnetic resonance imaging (MRI) has also been advocated, especially considering the physiologic information which can be gained from functional MRI; however, it is often too cumbersome to obtain in the acute trauma situation. Transesophageal echocardiography (TEE) has been shown to be a useful diagnostic tool, but this test may not be readily available in all institutions, and its accuracy is operator anatomy dependent. With TEE, there is also a risk of free aortic rupture due to patient gagging or Valsalva from inadequate sedation causing increase in intrathoracic pressure. In our experience, TEE has been most useful when the patient was sent to the operating room emergently for other life-threatening injuries and there remains a question regarding the diagnosis of acute TAT. Intraoperatively, TEE is useful in helping to rule in or out aortic injury. Operative exploration is now justified without the use of arteriography in the acute setting with a suggestive clinical picture along with other diagnostic radiologic findings such as that seen on plain radiographs, CT scans, and intraoperative TEE findings. Associated injuries are common, and acute TAT is rarely seen as an isolated entity. Injuries to other organ systems (intracranial, intra-abdominal), including major fractures (spine, pelvis), must be considered and treated if a successful outcome is to be obtained. When associated injuries are present, the cardiovascular surgeon should be involved with the treatment and prioritization of these injuries.

Three recent papers have attempted to grade CT findings of TAT along the lines of pathologic injury. The Simplest of these is the Vancouver simplified grading systems described by Lamarche et al. (J Thorac Cardiovasc Surg 2011). In order from least to most severe: Grade I is defined as an intimal flap/thrombus/hematoma <1 cm in length; Grade II as intimal flap/thrombus/hematoma >1 cm; Grade III pseudoaneurysm formation; and Grade IV free contrast extravasation. Furthermore, the authors correlated these findings to outcomes in a small subset of patients, advocating observation for all Grade I and some Grade II injuries with no mortality. Grade III injuries were treated with intervention and hospital survival in 90% and Grade IV with only 33% survival despite intervention. These favorable data can be used to guide operative decision making.

CTA can be both diagnostic and used for planning of operative intervention. Sizing of landing zones for TEVAR, presence of anomalous great vessel anatomy, patency of vertebral circulation, evidence of prior coronary grafting from internal mammary, angulation of aortic arch, and presence of other injuries can all be assessed with appropriate CTA. When CTA is being performed for suspected TAT, it is advantageous to scan the entire vascular tree from neck to femoral vessels. This allows for assessment of access vessels
in the event of possible TEVAR without adding to the contrast administration. One must consider that in younger patients with compliant vessels, intake CT scans may underestimate the actual size of the aorta and iliac system. Several millimeters of variance have been described in the under-resuscitated state. Furthermore, the more dynamic pulsation of the aorta in a young patient can be misrepresented on a static scan. This can lead to inappropriate oversizing of an endograft as will be described later. In patients with a documented anaphylactic reaction to iodine, or concern for renal failure, a noncontrasted thin cut CT scan can still be a useful adjunct in evaluating TAT and for operative planning and can be augmented by other modalities such as TEE and intravascular ultrasound (IVUS).