Arterial dissection

Arterial dissection occurs when there defect in the arterial tunica intima, leading to blood entering a virtual space between the tunica intima and tunica media. This forms a so-called false lumen inside this space. Unlike what the image at the top of the page shows, the false lumen may become larger than the true lumen. Blood may flow out of the false lumen through a second intimal tear.

The aorta is the artery most often affected by dissection, called aortic dissection.