Aortic dissection
- Lesion
Blood splits the layers of the aortic wall, tunnelling along the media. It causes tearing chest pain and can burst into the pericardium.
What it is
Aortic dissection occurs when blood enters the media, usually through an intimal tear, and separates its layers to form a blood-filled channel (false lumen). Most patients are men over 60 with long-standing hypertension; younger patients usually have a connective tissue disorder such as Marfan syndrome, or during pregnancy or cocaine use. Dissections of the ascending aorta (Stanford type A) are surgical emergencies; those limited to the descending aorta (type B) are often managed medically.
Structure
- Gross: an intimal tear with a blood clot dissecting within the wall; sometimes a ‘double-barrelled aorta’ when the false lumen re-enters and endothelialises.
- Microscopy: cystic medial degeneration is common but not always present; inflammation is usually absent.
Step by step
- The media is weakened (cystic medial degeneration, hypertensive damage or a genetic matrix defect).
- High shear stress opens a transverse tear in the intima.
- Blood under arterial pressure enters the media and splits it along its length.
- A false lumen forms; it may rupture outward, re-enter the true lumen or compress branches.
- Extension into the aortic root distorts the valve (regurgitation), the coronary ostia (infarction) or the pericardium (tamponade).
Clinical notes
- Signs: unequal arm pulses or pressures, new aortic regurgitation murmur, stroke, limb ischemia, widened mediastinum.
- Type A has high early mortality if not repaired; blood-pressure and heart-rate control are the first steps.
Test yourself
Think of the answer, then tap the question to see it.
What is the most important risk factor for aortic dissection?
Hypertension; connective tissue disorders such as Marfan syndrome account for most cases in young people.
Which part of the wall does the dissecting blood split?
The media, usually between its middle and outer thirds.
How does a proximal dissection cause sudden death?
Rupture into the pericardium with tamponade, or involvement of the coronary ostia or aortic valve.
What is the Stanford classification?
Type A involves the ascending aorta (with or without the descending); type B is limited to the aorta distal to the left subclavian artery.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Aortic dissection: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025); Marfan syndrome: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2025).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.