Evaluation of traumatic rupture of descending aorta by aortography and computed tomography: case report with follow-up

Aortography Delays Surgery of CT Proven Acute Traumatic Rupture of the Thoracic Aorta

A case of acute traumatic rupture of the thoracic aorta was diagnosed by dynamic CT. Angiographic confirmation was required, delaying surgical repair and contributing to the fatal outcome. If reliable findings of acute traumatic rupture of the thoracic aorta are shown by CT, we question the usefulness of angiographic confirmation in such cases.

Minimal aortic injury: a lesion associated with advancing diagnostic techniques

BACKGROUND

With the increasing use of high-resolution diagnostic techniques, minimal aortic injuries (MAI) are being recognized more frequently. Recently, we have used nonoperative therapy as definitive treatment for patients with MAI. The current study examines our institutional experience with these patients from July 1994 to June 2000.

METHODS

All patients suspected of blunt aortic injury (BAI) by screening helical CT (HCT) underwent confirmatory aortography with or without intravascular ultrasound (IVUS). MAI was defined as a small (<1 cm) intimal flap with minimal to no periaortic hematoma.

RESULTS

Of the 15,000 patients evaluated by screening HCT, 198 (1.3%) were suspected of having BAI. BAI was confirmed in 87 (44%), and 9 (10%) of these had MAI. The initial aortogram was considered normal in five of the MAI patients. The correct diagnosis was made by IVUS (four patients), and video angiography (one patient). One MAI patient had surgery, and two (22%) died of causes not related to the aortic injury. Follow-up studies were done on the six MAI patients that were discharged. In two, the flap had completely resolved, and in one it remained stable. The remaining three patients formed small pseudoaneurysms.

CONCLUSION

Ten percent of BAI diagnosed with high resolution techniques have MAI. These intimal injuries heal spontaneously and hence may be managed nonoperatively. However, the long-term natural history of these injuries is not known, and hence caution should be exercised in using this form of treatment.

Use of CT for diagnosis of traumatic rupture of the thoracic aorta

CT imaging of traumatic aortic rupture has been both advocated and disparaged in the current literature as a reliable diagnostic modality. In a retrospective review of blunt chest trauma patients at our institution evaluated by both thoracic CT and arteriography, we found a 17% false negative rate and a 39% false positive rate. Although we feel CT is not sufficiently sensitive at present to evaluate traumatic rupture of the aorta directly, it is an invaluable adjunctive imaging modality for stable blunt chest trauma patients with equivocal chest radiographs or arteriograms.

The normal mediastinum in blunt traumatic rupture of the thoracic aorta and brachiocephalic arteries

In a review of 52 articles, published between 1953 and 1989, 656 patients with blunt traumatic rupture of the thoracic aorta or brachiocephalic arteries were identified. Of these, 608 (92.7%) had an abnormal mediastinum on initial chest radiographs obtained in the emergency department, thus allowing early detection of the vascular injury. Unfortunately, 48 (7.3%) of these patients had a normal mediastinum on their initial chest radiographs. This appears to occur when the traumatic pseudoaneurysm is not accompanied by associated mediastinal hemorrhage or hematoma formation, and the pseudoaneurysm is either small or is situated in such a way that it does not alter the mediastinal contour. The use of accessory clinical and radiographic signs to indicate the need for aortography has been shown to be of very low yield, but would have allowed the early detection of an additional 5.6% of the reported cases. Performing aortography solely on the basis of a history of major decelerating blunt trauma to the thorax remains the only way, in the acute emergency department setting, to detect the 1.7% of patients with aortic or brachiocephalic arterial rupture who have no mediastinal abnormality or accessory clinical or radiographic signs of vascular injury. There is evidence from the literature, however, to suggest that the evaluation of serial chest radiographs obtained at close intervals for the first month following trauma for the development of mediastinal abnormality or large hemothorax is an acceptable alternative to the routine performance of aortography in those blunt chest trauma victims with no clinical or radiographic suspicion of vascular injury.

Computed tomography in the diagnosis of traumatic rupture of the thoracic aorta

Over a 26-month period, 25 patients admitted to the Trauma Unit at UCSD Medical Center following blunt trauma were investigated for suspected traumatic rupture of the thoracic aorta by computed tomography (CT) of the chest. A retrospective review of these patients was performed. Twenty-one (84%) also had CT of other body areas, most commonly the head or abdomen. Nine of the 25 patients subsequently had aortography; in 15 patients the CT findings were felt at the time to exclude rupture, and one patient was not investigated further because of severe head injuries. In general, if CT failed to show a mediastinal haematoma, aortography was not performed. However, five patients with CT evidence of a haematoma, including two with vertebral fractures, were not investigated by aortography. Two of the 25 patients (8%) had angiographically proven aortic ruptures; in both CT had shown not only a haematoma but also an abnormal outline of the aorta on contrast-enhanced scans. The haematoma was large in one patient and small in the other. Although 10 of the 25 patients had unenhanced scans, no case of aortic rupture is known to have been missed. During the same study period, 47 patients were investigated for suspected aortic rupture solely by aortography. Four patients (8% of this group) had aortic rupture, and two had subclavian or innominate artery ruptures. Only a minority (approximately one-quarter) also had CT of the head or abdomen. The role of CT in the diagnosis of traumatic rupture of the aorta is critically assessed in the light of our experience and a review of the literature.