Introduction
Aortic dissection refers to bleeding within and along the wall of the aorta and separation of the layers of the vessel. It usually begins with a tear in the tunica intima.
A false lumen develops alongside a true lumen. The aortic valve may be damaged and the branches of the aorta compromised. Typically, the false lumen re-enters the true lumen, creating a double-barrelled aorta. The false lumen may thrombose over time.
Classification
Stanford classification (modern)
Type A (66%): involves ascending aorta, with or without descending aorta
Type B (34%): involves only the descending aorta, beginning after the subclavian artery
DeBakey classification (old, deprecated)
I: ascending and descending aorta involved
II: only in ascending aorta
III: only descending aorta
Epidemiology
Affects 3-100,000. Males affected more than females (2:1 male:female). Peak incidence is in ages 50-70.
Causes
Dissections can occur as a result of:
- Tear in intima and subsequent propagation of blood into media (90%)
- Intramural haemorrhage and haematoma formation in media followed by intimal perforation
An intimal flap is characteristic of dissections.
Risk factors
- Hypertension
- Connective tissue disorders e.g. Marfan’s syndrome, Ehlers-Danlos syndrome, Turner’s syndrome
- Congenital cardiovascular abnormalities e.g. bicsuspid aortic valve, coarctation of aorta
- Pregnancy
- Cocaine use
- Iatrogenic – surgery to aorta e.g. aortic valve replacement, CABG
- Decelaration trauma
- Vasculitis
Clinical features
Sudden onset severe central chest pain. The pain has a tearing/stabbing character and may radiate to the back, arms and neck.
Other features include:
- Sweating and pallor
- Hypotension
- Blood pressure discrepancy between upper limbs
- Aortic regurgitation
- Syncope
Investigations
- Chest x-ray
- ECG: exclude STEMI
- CT and echocardiography: confirm diagnosis
- MRI: can be used in stable patients
Management
Resuscitate with:
- High-flow oxygen
- Fluids
- Analgesia
- Beta-blockers
Stanford type A
Urgent surgical treatment to replace the ascending aorta with a graft. Control blood pressure whilst awaiting surgery e.g. beta-blockers (calcium channel blockers if beta-blockers contraindicated)
Stanford type B
Medical management with beta-blockers (calcium channel blockers if beta-blockers contraindicated).
Complications
- Cardiac:
- Aortic regurgitation
- Myocardial infarction
- Tamponade
- Syncope
- Neurological e.g. stroke, spinal cord ischaemia
- Pulmonary e.g. pleural effusion
- Gastrointestinal e.g. mesenteric ischaemia
- Limb ischaemia
Prognosis
Mortality rate in type A is 25%, whilst type B is 10%.
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