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| Arterial dissections | |
|---|---|
 | |
| Aortic dissection | |
| Specialty | Vascular surgery |
Anarterial dissection is a tear within the wall of anartery, which allows blood to separate the wall layers. There are several types. Tears almost always occur in arterial walls, but avein wall tear has been documented.[1]
By separating a portion of the wall of the artery (a layer of thetunica media or in some casestunica intima), a tear creates twolumens or passages within the vessel, the original or true lumen, and the false lumen created by the new space within the wall of the artery. It is not yet clear if the tear in the innermost layer, thetunica intima, is secondary to the tear in thetunica media. Dissections originating in thetunica media are caused by disruption of thevasa vasorum. It is thought that dysfunction in the vasa vasorum is an underlying cause of dissections.[2]
Arterial dissections become life-threatening when growth of the false lumen preventsperfusion of the true lumen and the related end organs. For example, in anaortic dissection, if theleft subclavian arteryorifice weredistal to the origin of the dissection, then the left subclavian would be said to be perfused by the false lumen, while theleft common carotid (and its end organ, theleft hemisphere of the brain) ifproximal to the dissection, would be perfused by the true lumen proximal to the dissection.
Vessels and organs that are perfused from a false lumen may be well-perfused to varying degrees, from normal perfusion to no perfusion. In some cases, little to no end-organ damage or failure may be seen. Similarly, vessels and organs perfused from the true lumen but distal to the dissection may be perfused to varying degrees. In the above example, if the aortic dissection extended from proximal to the left subclavian artery takeoff to the mid descendingaorta, thecommon iliac arteries would be perfused from the true lumen distal to the dissection but would be at risk formalperfusion due to occlusion of the true lumen of the aorta by the false lumen.
Examples include:
Carotid and vertebral artery dissection are grouped together as "Cervical artery dissection" (CeAD).
As a disease family, arterial dissections share common features, including shared genetic risk variants, and commonly perturbed molecular pathways.[2] This includes dysfunction of theTGF-β pathway,extracellular matrix pathways, cellular metabolism andvascular smooth muscle cell contractility. Variants in genes includingCollagen genesCOL1A1, COL1A2, COL3A1, COL4A1, COL5A2, as well asextracellular matrix genesFBN1, FBN2, LOX, MFAP5;TGF-β pathways genesLRP1, TGFBR2, TGFB2; cytoskeletal/contractile pathway genes andPHACTR1, MYLK, PRKG1, and TLN1; andvascular smooth muscle cell geneSLC2A10 have all been implicated in at least two types of arterial dissection.[2] Certain comorbidities, such as lupus, may also increase the risk of arterial dissection.[4][5][6]