Characteristics

• Blood leakage through the aortic wall.

• Spontaneous rupture. Hypertension and atherosclerosis predispose to rupture. There may be an underlying aneurysm present, but rupture can occur with no preformed aneurysm.

• Traumatic rupture or transection following blunt trauma. Follows deceleration injury (RTA). Over 80% die before arrival at hospital. The weakest point, where rupture is likely to occur, is at the aortic isthmus, which is just distal to the origin of the left subclavian artery.

• The rupture may be revealed or concealed.

Clinical features

• There is often an antecedent history of a known aneurysm or appropriate trauma (e.g. RTA).

• Patients may be asymptomatic particularly if the rupture is small and intramural.

• Most cases present with severe substernal pain radiating through to the back. Patients may be breathless, hypotensive, tachycardic or moribund.

Radiological features

• CXR – look for widening of the mediastinum on CXRs. It is very rare to see aortic rupture in a patient with a normal CXR. Other features on the CXR include loss of the aortic contour, focal dilatation of the aorta and a left apical cap (blood tracking up the mediastinal pleural space). Signs of chest trauma – rib fractures (1st and 2nd), haemopneumothorax and downward displacement of a bronchus.

• Unenhanced CT – may show crescentic high attenuation within a thickened aortic wall only (intramural haematoma, at risk of imminent dissection or rupture). Rupture is associated with extensive mediastinal blood. A pseudoaneurysm may be present. There may be injuries to major branching vessels from the aorta.

• Angiography or transoesophageal echocardiography – may be helpful to confirm small intimal tears of the aortic wall. However, contrast-enhanced MRA is a sensitive alternative investigation to standard invasive angiography.