Thickening of a blood vessel may occur for a number of reasons. It is usually a result of changes within the vessel wall causing it to become thicker than normal. Alternatively it may arise from an enlargement of the vessel as a whole due to dilatation or birth defects.
Thickening of the wall may affect only one part of an artery or vein or result in thickening along the entire length of the vessel. Irregular thickening can lead to a host of complications as it may result in weakening of the wall over time, cause turbulent blood flow within the vessel or narrow the vessel lumen. Larger, focal thickening may also press on surrounding structures.
Age related thickening of the wall of the blood vessel is a common occurrence however, other diseases may cause a thickening of the walls.
Causes of a Thickened Vessel
An aneurysm is the bulging of a portion of a blood vessel. It is an abnormal dilatation, like a balloon, and may affect an intact vessel wall (true aneurysm) or diseased wall (false aneurysm).It is not an actual thickening of the blood vessel wall but is rather a protrusion of the wall.
Aortic dissection, also known as a dissecting aneurysm, occurs when blood enters a tear in the wall of the aorta. It forms a blood-filled channel within the wall that can rupture through the outer tunica adventitia layer. If left untreated, it may lead to death.
Atherosclerosis and Arteriosclerosis
Atherosclerosis is the formation of plaques within the arterial wall which bulges into the lumen of the vessel. It tends to affect large to medium sized arteries. Apart from the plaques, inflammation of the vessel wall and smooth muscle proliferation as part of atherogenesis may also cause swelling of the affected artery.
Arteriosclerosis affects smaller arteries and arterioles. Two types of arteriosclerosis known as hyaline and hyperplastic arteriosclerosis causes thickening of the vessel wall and results in narrowing of the artery. Another type of arteriosclerosis known as Monckeberg medial sclerosis does not cause arterial narrowing (stenosis) but calcified deposits build up in the wall.
Certain conditions, like fibromuscular dysplasia, results in an irregular thickening of the arterial wall with associated narrowing of the artery.
Persistent vasoconstriction as seen in primary hypertension may cause thickening of the affected vessel wall
Raynaud phenomenon is the excessive vasoconstriction of the small arteries and arterioles of the hands and feet. In the late stages of the disease, thickening of the intimal layer of the vessel wall may be noted.
A tumor may cause focal, irregular thickening of the vessel wall. This is a result of the growth of the mass and may affect the endothelial lining or connective tissue.
Proliferative restenosis is a complication of angioplasty and the use of bare metal stents. These procedures may result in thickening of the intimal layer of the vessel. New generation stents have coatings to prevent proliferation and thickening. In vascular replacement surgery, intimal thickening and atheromatous plaques may be seen in the grafts.
Vasculitis is the inflammation of the wall of a blood vessel. It may occur for a number of reasons, including infection, immune-mediated factors, toxic compounds, mechanical trauma, drugs and irradiation.
There are various types of vasculitis and thickening of the vessel wall may be permanent due to fibrosis following persistent inflammation. This is most evident in giant-cell (temporal) arteritis, Takayasu arteritis, polyarteritis nodosa, Kawasaki disease and Buerger disease (thromboangiitis obliterans).
Phlebitis, which is the inflammation of a vein, is commonly seen in the deep leg veins that it is caused by a thrombus (thrombophlebitis).