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Aneurysm

life science Maturity 11-13 Next article →

An aneurysm is a localized, abnormal bulging of a blood vessel wall. It is often compared to a tiny balloon or a bubble. This bulge occurs because of a weak spot in the vessel structure. Aneurysms can be caused by hereditary conditions or acquired diseases. They can also serve as a nidus, which is a starting point, for a blood clot called thrombosis. As an aneurysm increases in size, the risk of a rupture grows. A rupture can lead to uncontrolled bleeding, which is a very serious medical event.

Arterial aneurysm
Arterial aneurysm

Doctors classify aneurysms by their type, morphology, or location. A true aneurysm involves all three layers of the arterial wall. These layers are the intima, the media, and the adventitia. True aneurysms can be caused by atherosclerosis, which is a buildup of plaque. They may also be congenital, meaning they are present from birth. In contrast, a false aneurysm, or pseudoaneurysm, is different. This occurs when blood leaks completely out of an artery or vein. The blood is then held in a cavity by the surrounding tissue.

Ultrasonography of a thrombosed great saphenous vein aneurysm
Ultrasonography of a thrombosed great saphenous vein aneurysm

Scientists also describe aneurysms by their macroscopic shape, or their outward appearance. Saccular aneurysms are spherical in shape and are often called "berry" aneurysms. They involve only a portion of the vessel wall and have a "neck" connecting them to the parent artery. This rounded area is known as the dome.

Aneurysm vortex
Aneurysm vortex

Fusiform aneurysms are spindle-shaped. These vary in both diameter and length. They often affect large sections of the aorta. The diameter of a fusiform aneurysm can extend up to 10 cm. The shape of an aneurysm does not identify the specific disease that caused it.

Location is another way to categorize these bulges. Aneurysms can occur in almost any blood vessel. Cerebral aneurysms occur in the brain, often in the circle of Willis. These can cause severe strokes. Aortic aneurysms affect the body's largest artery. They can be thoracic, located in the chest, or abdominal, located in the belly.

Blausen 0001 AbdominalAorticAneurysm 01
Blausen 0001 AbdominalAorticAneurysm 01

Other locations include the heart, the kidneys, and the legs. For example, a popliteal artery aneurysm occurs in the leg. An abdominal aortic aneurysm is often diagnosed using ultrasonography or MRI.

Aortic Aneurism 76F 3D SR Nevit Dilmen
Aortic Aneurism 76F 3D SR Nevit Dilmen

Size is a critical factor in managing an aneurysm. In the abdominal aorta, an aneurysm is usually defined by a diameter over 3 cm. A normal aorta is approximately 2 cm in diameter. If the diameter is between 2.0 cm and 3.0 cm, it is called ectatic. If it is between 3.0 cm and 5.0 cm, it is moderate. An aneurysm is considered large or severe if the diameter exceeds 5.5 cm. For the common iliac artery, an aneurysm is defined as a diameter of 18 mm or more. These measurements help doctors decide on necessary treatments.

Many risk factors can lead to the formation of an aneurysm. These include diabetes, obesity, and high blood pressure, also known as hypertension. Tobacco use and alcoholism are also significant risks. Some people have connective tissue disorders, such as Marfan syndrome or Ehlers-Danlos syndrome. These conditions affect the strength of the body's tissues. In some cases, infections can cause a mycotic aneurysm. This is an aneurysm that results from a bacterial infection in the arterial wall. Less than 3% of abdominal aortic aneurysms are mycotic.

The mechanical properties of the vessel wall change during an aneurysm. A healthy blood vessel is very tough and can absorb energy before it ruptures. This is due to a high volume of elastin and smooth muscle. In an aneurysmal aorta, the composition changes significantly. There is a much higher volume of collagen and ground substance. However, there is much less elastin and smooth muscle compared to a normal aorta. This makes the vessel wall less stable. The vessel becomes prone to rupture even under normal blood pressure and flow.

EndoStentandCoilMark
EndoStentandCoilMark
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🖼️ Images & Media (7)
File:Arterial aneurysm.jpg
Arterial aneurysm.jpg
File:Ultrasonography of a thrombosed great saphenous vein aneurysm.jpg
Ultrasonography of a thrombosed great...
File:Blausen 0001 AbdominalAorticAneurysm 01.png
Blausen 0001 AbdominalAorticAneurysm 01.png
Aortic Aneurism 76F 3D SR Nevit Dilmen.stl
File:Ruptured 7mm left vertebral artery aneurysm.png
Ruptured 7mm left vertebral artery aneurysm.png
File:EndoStentandCoilMark.png
EndoStentandCoilMark.png
File:Aneurysm vortex.svg
Aneurysm vortex.svg
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