An arterial dissection is a tear within the wall of an

artery An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

, which allows blood to separate the wall layers. There are several types. Tears almost always occur in arterial walls, but a

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

wall tear has been documented. By separating a portion of the wall of the artery (a layer of the

tunica media The tunica media (Neo-Latin "middle coat"), or media for short, is the middle tunica (layer) of an artery or vein. It lies between the internal elastic lamina of the tunica intima on the inside and the tunica externa on the outside. Artery The ...

or in some cases

tunica intima The tunica intima (Neo-Latin "inner coat"), or intima for short, is the innermost tunica (biology), tunica (layer) of an artery or vein. It is made up of one layer of endothelium, endothelial cells (and macrophages in areas of disturbed blood flo ...

), a tear creates two lumens 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, the

, is secondary to the tear in the

. Dissections originating in the

are caused by disruption of the

vasa vasorum Vasa vasorum are networks of small blood vessels that supply the walls of large blood vessels, such as elastic arteries (e.g., the aorta) and large veins (e.g., the venae cavae). The name derives . Occasionally, two different singular forms ar ...

. It is thought that dysfunction in the vasa vasorum is an underlying cause of dissections.

Description

Arterial dissections become life-threatening when growth of the false lumen prevents

perfusion Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ (anatomy), organ or a tissue (biology), tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion may also refer t ...

of the true lumen and the related end organs. For example, in an

aortic dissection Aortic dissection (AD) occurs when an injury to the innermost layer of the aorta allows blood to flow between the layers of the aortic wall, forcing the layers apart. In most cases, this is associated with a sudden onset of agonizing ches ...

, if the

left subclavian artery In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplie ...

orifice An orifice is any opening, mouth, hole or vent, as in a pipe, a plate, or a body * Body orifice, any opening in the body of a human or animal *Orifice plate, a restriction used to measure flow or to control pressure or flow, sometimes given specia ...

were

distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

to the origin of the dissection, then the left subclavian would be said to be perfused by the false lumen, while the left common carotid (and its end organ, the left hemisphere of the brain) if

proximal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

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 descending

aorta The aorta ( ; : aortas or aortae) is the main and largest artery in the human body, originating from the Ventricle (heart), left ventricle of the heart, branching upwards immediately after, and extending down to the abdomen, where it splits at ...

, the

common iliac arteries The common iliac artery is a large artery of the abdomen paired on each side. It originates from the aortic bifurcation at the level of the 4th lumbar vertebra. It ends in front of the sacroiliac joint, one on either side, and each bifurcates in ...

would be perfused from the true lumen distal to the dissection but would be at risk for malperfusion due to occlusion of the true lumen of the aorta by the false lumen.

Types

Examples include: *

Aortic dissection Aortic dissection (AD) occurs when an injury to the innermost layer of the aorta allows blood to flow between the layers of the aortic wall, forcing the layers apart. In most cases, this is associated with a sudden onset of agonizing ches ...

(

) * Coronary artery dissection (

coronary artery The coronary arteries are the arterial blood vessels of coronary circulation, which transport oxygenated blood to the heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any other tissue or organ of ...

) also referred to as

spontaneous coronary artery dissection Spontaneous coronary artery dissection (SCAD) is an uncommon but potentially lethal condition in which one of the coronary arteries that supply the heart, spontaneously develops a blood collection, or hematoma, within the artery wall due to a tea ...

or SCAD *

Pulmonary artery dissection The lungs are the primary Organ (biology), organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the Vertebral column, backbone on either side of the heart. Their ...

(

pulmonary artery A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and ...

) an extremely rare condition as a complication of

pulmonary hypertension Pulmonary hypertension (PH or PHTN) is a condition of increased blood pressure in the pulmonary artery, arteries of the lungs. Symptoms include dypsnea, shortness of breath, Syncope (medicine), fainting, tiredness, chest pain, pedal edema, swell ...

Carotid artery dissection Carotid artery dissection is a serious condition in which a tear forms in one of the two main carotid arteries in the neck, allowing blood to enter the artery wall and separate its layers (dissection). This separation can lead to the formation of ...

(

carotid artery Carotid artery may refer to: * Common carotid artery, often "carotids" or "carotid", an artery on each side of the neck which divides into the external carotid artery and internal carotid artery * External carotid artery, an artery on each side of ...

) *

Vertebral artery dissection Vertebral artery dissection (VAD) is a flap-like tear of the inner lining of the vertebral artery, which is located in the neck and supplies blood to the brain. After the tear, blood enters the arterial wall and forms a blood clot, thickening t ...

(

vertebral artery The vertebral arteries are major artery, arteries of the neck. Typically, the vertebral arteries originate from the subclavian arteries. Each vessel courses superiorly along each side of the neck, merging within the skull to form the single, m ...

) Carotid and vertebral artery dissection are grouped together as "

Cervical artery dissection Cervical artery dissection is dissection of one of the layers that compose the carotid and vertebral artery in the neck (cervix). They include: * Carotid artery dissection, a separation of the layers of the artery wall supplying oxygen-bearing bloo ...

" (CeAD).

Common features

As a disease family, arterial dissections share common features, including shared genetic risk variants, and commonly perturbed molecular pathways. This includes dysfunction of the

TGF-β Transforming growth factor beta (TGF-β) is a multifunctional cytokine belonging to the transforming growth factor superfamily that includes three different mammalian isoforms (TGF-β 1 to 3, HGNC symbols TGFB1, TGFB2, TGFB3) and many other ...

pathway,

extracellular matrix In biology, the extracellular matrix (ECM), also called intercellular matrix (ICM), is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and bio ...

pathways, cellular metabolism and vascular smooth muscle cell contractility. Variants in genes including

Collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...

genes ''COL1A1, COL1A2, COL3A1, COL4A1, COL5A2'', as well as

genes ''FBN1, FBN2, LOX, MFAP5'';

pathways genes ''

LRP1 Low density lipoprotein receptor-related protein 1 (LRP1), also known as alpha-2-macroglobulin receptor (A2MR), apolipoprotein E receptor (APOER) or cluster of differentiation 91 (CD91), is a protein forming a receptor found in the plasma membra ...

, TGFBR2, TGFB2''; cytoskeletal/contractile pathway genes and ''

PHACTR1 Phosphatase and actin regulator 1 (PHACTR1) is a protein that in humans is encoded by the ''PHACTR1'' gene on chromosome 6. It is most significantly expressed in the globus pallidus of the brain. PHACTR1 is an actin and protein phosphatase 1 (PP1 ...

, MYLK, PRKG1, and TLN1''; and vascular smooth muscle cell gene ''SLC2A10'' have all been implicated in at least two types of arterial dissection. Certain comorbidities, such as lupus, may also increase the risk of arterial dissection.

References

External links

{{Vascular diseases Gross pathology Angiology