VASCULAR PATHOLOGIES BYDR ABIODUN MARK.A
Hyaline arteriolosclerosis • Hyaline arteriolosclerosis, also arterial hyalinosis and arteriolar hyalinosis, refers to thickening of the walls of arterioles by the deposition of homogeneous pink hyaline material. • Lesions reflect leakage of plasma components across vascular endothelium and excessive extracellular matrix production by smooth muscle cells, usually secondary to hypertension. • It is a type of arteriolosclerosis, which refers to hardening of the arteriolar wall. • It is associated with aging, hypertension, diabetes mellitus and may be seen in response to certain drugs (calcineurin inhibitors).
Hyperplastic arteriolosclerosis • Hyperplastic arteriolosclerosis is a type of arteriolosclerosis involving a narrowed lumen. • The term "onion-skin" is sometimes used to describe this form of vessel with thickened concentric smooth muscle cell layer and thickened, duplicated basement membrane. • In malignant hypertension these hyperplastic changes are often accompanied by fibrinoid necrosis of the arterial intima and media. • These changes are most prominent in the kidney and can lead to ischemia and acute renal failure.
Atherosclerosis • Atherosclerosis (also known as arteriosclerotic vascular disease or ASVD) is a specific form of arteriosclerosis in which an artery wall thickens as a result of the accumulation of calcium and fatty materials such as cholesterol and triglyceride. It reduces the elasticity of the artery walls and therefore allows less blood to travel through. • The risk factors for atherosclerosis are diagrammed here in relation to the mechanisms that favor development of arterial atheroma formation. Atherosclerosis is a potentially reversible process. • The process of reversal can be summarized as follows: eat fewer total calories and exercise more.
Normal coronary artery • This is a normal coronary artery with no atherosclerosis and a widely patent lumen that can carry as much blood as the myocardium requires. There is no impediment to blood flow.
Coronary artherosclerosis. • The degree of atherosclerosis is much greater in this coronary artery, and the lumen is narrowed by half. • A small area of calcification is seen in the plaque at the right.
Aneurysm • An aneurysm or aneurism "dilation", is a localized, blood-filled balloon-like bulge in the wall of a blood vessel. • Aneurysms may be classified by type, morphology, or location. • A true aneurysm is one that involves all three layers of the wall of an artery (intima, media and adventitia). • A false aneurysm, or pseudo-aneurysm, is a collection of blood leaking completely out of an artery or vein, but confined next to the vessel by the surrounding tissue.
Aneurysms cont’s. • Morbidity and death due to aneurysms is due to the following: • Rupture. • Impingement on adjacent structures. • Embolism from a mural thrombus.
Causes of aneurysms. • The 2 most common causes of aneurysm are atherosclerosis and cystic medial degeneration. • Other causes include syphilis, trauma, polyathritisnodosa, congenital infection and some other infections (mycotic aneurysms). • Atherosclerotic aneurysms usually but not exclusively occurs in the abdominal aorta usually between the renal artery and the bifurcation of the iliac arteries.
Abdominal aortic aneurysm • Abdominal aortic aneurysm (also known as AAA,) is a localized dilatation (ballooning) of the abdominal aorta exceeding the normal diameter by more than 50 percent, and is the most common form of aortic aneurysm. • Approximately 90 percent of abdominal aortic aneurysms occur infrarenally (below the kidneys). • Abdominal aortic aneurysms occur most commonly in individuals between 65 and 75 years old and are more common among men and smokers. The major complication of abdominal aortic aneurysms is rupture, which is life-threatening, as large amounts of blood spill into the abdominal cavity, and can lead to death within minutes
Thoracic aortic aneurysm • A thoracic aortic aneurysm is an aortic aneurysm that presents primarily in the thorax. • An thoracic aortic aneurysm is the "ballooning" of the upper aspect of the aorta, below the rib cage. Untreated or unrecognized they can be fatal . • Thoracic aneurysms are less common than an abdominal aortic aneurysm. • Aneurysms in patients younger than 40 usually involve the ascending aorta due to a weakening of the aortic wall associated with connective tissue disorders like the Marfan and Ehler-Danlos syndromes.
Cystic medial necrosis • This mucin stain of the wall of the aorta demonstrates cystic medial necrosis, typical for Marfan's syndrome and causes the connective tissue weakness that explains the aortic dissection. Pink elastic fibers, instead of running in parallel arrays, are disrupted by pools of blue mucinous ground substance.
Aortic dissection • Aortic dissection occurs when a tear in the inner wall of the aorta causes blood to flow between the layers of the wall of the aorta, forcing the layers apart. • This is usually due to hypertension in older people and caused by C.T disorders in younger people. • In most cases this is associated with a tearing/excruciating chest pain that usually begins in the anterior chest wall and radiates to the back and downwards as the dissection continues. • Aortic dissection is a medical emergency and can quickly lead to death
H & E staining of a medium-sized artery with giant cell arteritis. Note thickening of the media and intima with inflammatory cells.
Giant-cell arteritis • Giant-cell arteritis (GCA or temporal arteritis or cranial arteritis) is an inflammatory disease of blood vessels most commonly involving large and medium arteries of the head, predominantly the branches of the external carotid artery. • It is a form of vasculitis. The most serious complication of GCA is permanent blindness, though this can be prevented by prompt treatment with corticosteroids. • The name (giant cell arteritis) reflects the type of inflammatory cell involved as seen on a biopsy.
PAN. • Classic polyarteritisnodosa (PAN or c-PAN) is a systemic vasculitis characterized by necrotizing inflammatory lesions that affect medium-sized and small muscular arteries, preferentially at vessel bifurcations, resulting in microaneurysm formation, aneurysmal rupture with hemorrhage, thrombosis, and, consequently, organ ischemia or infarction.
Thromboangiitisobliterans • Is a rare disease in which blood vessels of the hands and feet become blocked. • Thromboangiitisobliterans (Buerger disease) is caused by small blood vessels that become inflamed and swollen. The blood vessels then narrow or become completely blocked by blood clots (thrombosis). • Blood vessels of the hands and feet are especially affected. Arteries are more affected than veins. Women and older adults are affected less often. • This condition mostly affects young men ages 20 - 40, who are heavy smokers or chew tobacco.