Cardiovascular pathology - BLOOD VESSELS Flashcards
What is atherosclerosis?
A degenerative condition of arteries characterised by a fibrous and lipid rich plaque with variable inflammation, calcification and a tendency to thrombosis
What is seen in the initiation stage of atherosclerosis?
- Endothelial dysfunction and injury around sites of damage, with subsequent lipid accumulation at sites of impaired endothelial barrier
- Local cellular proliferation and incorporation of oxidised lipoproteins occurs
- Mural thrombi (thrombi adhered to vessel wall) heal the vessel and repeat of cycle
What is seen in the adaption stage of atherosclerosis?
- As plaque progresses to 50% of lumen size, vessel can no longer compensate by re- modelling
- Becomes narrowed – drives cell turnover within the plaque
- New matrix surfaces and degradation of matrix
- May progress to unstable plaque
What is seen in the clinical stage of atherosclerosis?
- Plaque continues to encroach upon the lumen and runs the risk of haemorrhage
- T cell accumulation is stimulated
- Inflammatory reaction against the plaque contents – complications develop incl. ulceration, fissuring, calcification and aneurysm change
What is seen in the pathological stages of atherosclerosis?
- Fatty streak – these show as macrophages filled with abundant lipid (foam cells) but also smooth muscle cells with fat
- Intimal cell mass – these are collections of muscle cells and connective tissue without lipid cushions
- The atheromatous plaque
- Complicated plaque = calcification, mural thrombus, vulnerable plaque
What are the complications of plaque rupture?
- Acute occlusion due to thrombus
- Chronic narrowing of vessel lumen with healing of the local thrombus
- Aneurysm change
- Embolism of thrombus +/- plaque lipid content
What are risk factors for atherosclerosis?
- Hypertension
- Serum cholesterol level
- Tobacco smoking
- Diabetes
- Increasing age
- Male > female
- Inactive and stressful life patterns
What is the hypertension background of atherosclerosis?
- Altered renin-angiotensin system elevates BP by impairing sympathetic output, increasing mineralocorticoid secretion and direct vaso-constriction
- This is balanced by atrial natriuretic factor
- Changes to auto-regulation produce an increase in peripheral resistance, which would normally allow increased BP, diuresis and restoration of normal pressure and volume
- Hypertension alters blood vessel walls whereby the lumen size is decreased as the wall thickness increases
What are the acquired causes of atherosclerosis?
- Chronic vascular disease
- Diabetes
- Primary elevation of
aldosterone - Cushing syndrome
- Hyperthyroidism
- Exogenous (drugs) agents
What is arteriosclerosis?
- Hyaline arteriosclerosis shows a deposition of basement membrane-like material and accumulation of plasma proteins within the vessel wall
- Accelerated in diabetic and hypertensive individuals
What is malignant hypertension defined as?
> 160/110mmHg
What is vasculitis?
An inflammatory and variably necrotic process centred on the blood vessels that may involve arteries, veins or capillaries
What is the immune background of vasculitis?
- Deposition of immune complexes
- Direct attack on vessels by antibodies
- Cell mediated immunity
- Viral infection
- Serum sickness = model
Which viral antigens can be found in human vasculitis cases?
HSV, CMV, Parvovirus
What is Polyarteritis nodosa (PAN)?
- Affects medium and small muscular arteries
- Patchy necrotising arteritis with neutrophils, lymphocytes, plasma cells and macrophages
What is Hypersensitivty angiitis?
- Affects the smallest arteries and arterioles
- Microscopically fibrinoid necrosis and inflammation around small vessels
What is Churg-Strauss syndrome?
- Necrotising legions of small medium arteries, arterioles and veins affecting lungs/ spleen/ kidney/ heart/ liver/ CAN
- Strong association with asthma
What is the most common type of vasculitis?
Giant cell arteritis
Describe the features of giant cell arteritis?
- Can involve large arteries (aortic aneurysm/dissection)
- Genetic background with family
- Thickened blood vessel, often palpable
- Granulomatous inflammation involving full thickness of the wall with macrophages, lymphocytes, plasma cells, neutrophils and occasionally eosinophils
- Giant cells tend to congregate around Internal elastic lamina
- Variable necrosis
- Old areas of inflammation show up as focal scars with fragmentation of elastic laminae, thrombosis may occur
- Often benign, but if affects ocular artery it results in blindness
What is Wegener’s granulomatosis?
Vasculitis of the respiratory tract and kidney, may involve small arteries and veins