Arterial dissection occurs when blood enters the media through a tear or ulcer in the intima and tracks along the media, forming a second blood-filled channel within the wall. The normal lumen lined by intima is called the true lumen and the blood-filled channel in the media is called the false lumen. The false lumen is at a higher pressure than the true lumen due to poor outflow.
Pathology
Etiology
In most cases the vessel wall is abnormal.
hypertension 3 (pathogenesis: medial degeneration)
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inherited connective tissue disorders (pathogenesis: medial degeneration)
atherosclerosis (pathogenesis: penetrating ulcer)
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vasculitides (pathogenesis: inflammation)
e.g. Behcet disease
pregnancy (pathogenesis: unknown)
iatrogenic: aortic catheterization, intra-aortic balloon pump
relapsing polychondritis (rare): pathogenesis?