Key points

• Aneurysm disease affects the thoracic aorta much less commonly than the infrarenal aorta

• Most patients are asymptomatic but may have chest, back or abdominal pain

• Diagnosis is on computed tomography (CT) angiogram and the Crawford classification is used to describe the extent of the aneurysm

• Intervention is recommended if the aneurysm is >6 cm (or 5 cm in the presence of a connective tissue disorder or a family history of rupture)

• Open surgery remains the standard treatment for complex suprarenal, thoracic and thoracoabdominal aneurysms

• Specific complications incude risks of paraplegia and renal and visceral ischaemia

• Endovascular repair is suitable for descending thoracic aneurysms

Epidemiology

The incidence of aneurysmal disease affecting the suprarenal aorta and the thoracic aorta is difficult to estimate since it is a condition that is usually asymptomatic and rupture, which is often rapidly fatal, is commonly misattributed to other causes such as myocardial infarction or pulmonary embolism. The incidence is approximately 6 per 100,000 people per year. Males are affected about twice as commonly as females but interestingly the gender difference is less than for infrarenal aortic aneurysms, where the ratio is up to 7:1.

Natural history data are scarce, typically involving retrospective observation of patients not fit for open repair. In a series of 1600 cases the rupture risk for a 6 cm aneurysm of the thoracic aorta was 3.6% per year and for the composite endpoint of rupture/dissection/death the annual risk was 14.1%.

Key points

• Aortic dissection may be defined as acute (<2 weeks since symptoms) or chronic (>2 weeks since symptoms)

• Acute aortic dissection is associated with hypertension and pre-existing disease of the aortic wall

• Patients usually present with severe, tearing chest and back pain

• Diagnosis is with transoesophageal echocardiogram and computed tomography (CT) angiogram

• The Stanford or DeBakey classifications are used to describe the pattern of dissection

• Type A dissections require early surgical treatment. The in-hospital mortality is high but the prognosis is very good in patients surviving to discharge from hospital

• Type B dissections are treated medically in the first instance. The in-hospital mortality is much lower but complications may occur following discharge

• Chronic type B dissection may result in aortic dilatation and rupture so surveillance is required

• Endovascular strategies have a role in some situations for acute type A dissection and acute type B dissection, but the role in chronic type B dissection is unclear

Epidemiology

Aortic dissection occurs with an incidence of approximately 3 per 100,000 per year. Accurate estimates are difficult due to the high out-of-hospital mortality for this condition and the low post-mortem rate in most countries. It affects males twice as commonly as females and the risk increases with age. Interestingly, as with a number of other cardiovascular conditions, it demonstrates circadian variation with a peak incidence early in the morning and during the winter. This pattern correlates with times of peak blood pressure.