Vascular pathology Flashcards
What is an atheroma?
Condition characterised by focal accumulation of lipid in the intima of arteries (inner most layer)
What is atherosclerosis?
Atheroma causing hardening of arteries
List 7 risk factors of atherosclerosis?
Increasing age
Male
Smoking - carbon monoxide damages endothelial cells lining the arteries
Hypertension - blood cells don’t normally contact the endothelium, in hypertension = turbulence - blood cells contact endothelium
Diabetes mellitus
Raised LDL - cholesterol blood levels
Family history
List 3 pre-disposing factors of atherosclerosis?
Obesity
Lack of exercise
Low socio-economic status
List the stages of an atherosclerosis lesion
Fatty streak
Fibrolipid plaque
Complicated lesion
How do veins and arteries differ histologically?
Arteries are smaller and have much thicker walls
Describe the wall of an artery?
Inner = internal elastic lamina
Tunica Media
External elastic lamina
Outer = Tunica adventitia
Name 2 types of arteries?
Elastic and muscular
In a muscular artery what is the tunica media made of?
Smooth muscle cells
In an elastic artery where is elastic material found?
Between inner and outer elastic lamina
What is the first stage in the formation of an atherosclerosis lesion?
Fatty streak
What is the first event occurring during the formation of a fatty streak? What is the effect of this?
Endothelial image leading to permeability, monocyte adhesion to the endothelium so monocytes and LDL can enter the artery
What is the major characteristic of a fatty streak?
Foamy macrophages - Monocytes that have entered and injected LDLs. They cannot digest the fat so they sit in the intima
Through what process do monocytes enter the intima?
Diapedesis
What triggers monocytes to invest LDLs?
Cytokines released form T cells within the fatty streak cause maturation into macrophages, these ingest the LDLs and form foam cells
How can a fatty streak develop into a fibrolipid plaque?
T cells release cytokines that cause the release of smooth muscle cells from the tunica media into the intima. These ingest LDLs
How does the artery change when a fatty streak develops into a fibrolipid plaque?
The plaque becomes more prominent and elevated
How does the artery change when a fatty streak develops into a fibrolipid plaque?
The plaque becomes more prominent and elevated
Fibrolipid plaques bulge into what structure?
Lumen of artery
Describe what occurs in the fibrolipid plaque?
Smooth muscle cells migrate to the surface of the intima, these are followed by fibroblasts .
Proliferation occurs, there is more lipid uptake and collagen is produced
What cells are seen in a fibrolipid plaque?
Foamy macrophages, Smooth muscle cells, lymphocytes and fibroblasts
How does a lipid lake form in a fibrolipid plaque?
Foamy macrophages breakdown and form a lipid lake
In the fibrolipid plaque stage, is the endothelium intact?
Yes but it is bulging into the lumen - this gives the opportunity for blood cells and platelets to impact on the surface of the fibrolipid plaque
What follows the impaction of platelets onto the surface fo the fibrolipid plaque?
Formation of complicated lesion
What is the consequence of a complicated lesion forming?
Leads to thrombosis
Describe how a complicated lesion forms?
Occlusion of platelets on the surface of the fibrolipid plaque and endothelium layer is lost. Causes the clotting cascade to begin. This forms a thrombus on the plaque.
What 5 things occur after the formation of a complicated lesion? Why?
Haemorrhage into plaques Plaque fissuring and rupture Embolism Calcification Aneurysm formation Because complicated lesions can occlude the whole artery
Where does atherosclerosis occur in the arteries?
Bifurcations of arteries
more possibility for platelets to impact
Which artery are clinical effects most prominent?
Coronary arteries
List some consequences of atherosclerosis?
Ischaemic heart disease
Aortic aneurysm
Small bowel ischaemia and infarction
Peripheral vascular disease
What is angina pectorals?
Pain in the left side down the arm during exercise
What is myocardial infarction?
Heart muscle dies as a result of ischaemia
What is intermittent claudication? What causes it?
Pain in legs during exercise due to peripheral vascular disease
Name 3 ways atherosclerosis can be managed?
Lifestyle
Medical
Surgical
How can lifestyle be used to manage atherosclerosis?
Healthy eating, exercise and not-smoking
Name 3 drugs used to manage atherosclerosis?
Cholesterol medications, anti-platelet medications, beta blocker medication
Name 4 surgical process used to manage atherosclerosis?
Angioplasty
Stent
Bypass
Endarterectomy
What is a thrombus?
Solid mass of blood constitutents formed within the vascular system during life
How do thrombus and clot differ?
Clot forms outside vascular system
What is an embolism?
Passive transport of a substance within the vascular system
What is ischaemia?
Inappropriate reduction in blood supply to an organ or tissue
What is infarction?
Death of tissue due to ischaemia
What is an aneurysm?
Localised permanent abnormal dilation of a blood vessel due to weakening of the blood vessel wall
What 3 things are known to result in thrombosis?
Changes in the intimal surface of vessel
Changes in the pattern of blood flow
Changes in the blood constituents
What are Virchows Triad?
Changes in the intimal surface of vessel
Changes in the pattern of blood flow
Changes in the blood constituents
3 factors that result in thrombosis
What is a good example of changes to the intimal surface that will result in thrombosis?
Atherosclerosis - intimal surface ulcerated
What is a good example of changes in pattern of blood flow that will result in thrombosis?
Venostasis
Blood is stagnant, platelets drop out and clot
Injury or compression where the turbulence results in adherence of platelets to endothelium = thrombus
What is a good example of changes in the blood constituents that will result in thrombosis?
Anything that makes the blood hyper-coagulable
Why do atheromas lead to thrombosis?
Platelets land on top of the atheroma and aggregate and release clotting factors and fibrin forms trapping RBC = more aggregation, causing propagation of the thrombus
How do Venus thrombus occurs?
Due to stasis often around valves
In what patients often does Venus thrombus occur?
Burns and trauma, after surgery, cardiac failure, pregnancy, immobility, long haul lights
What is thrombophlebitis?
Inflammation of the deep vein
What is phlebothrombosis?
Stagnation of the deep vein so platelets drop out of circulation and form a thrombus
Where in the heart can cardiac thrombosis occur?
Atria or valves
In the atrium, conditions like atrial fibrillation and mitral stenosis occurs, how can this cause thrombosis?
Change in blood flow - platelets contact normal endothelium due to turbulence
In the valves, thrombosis can occur due to rheumatic fever and endocarditis, why is this?
Due to vegetations, thrombosis occurs on top of these
How can thrombosis occur in the ventricle?
If myocardial infarction occurs and the heart wall dies and thrombus can occur here
4 fates of thrombi?
Lysis and resolution
Retraction and re-canalisation
organisation and scarring
embolism
What is the best outcome of thrombi?
Lysis and resolution
Describe lysis and resolution of thrombi?
Complete dissolution of thrombus and complete return to normal tissue architecture
Describe retraction and re-canalisation?
Thrombus and clots can both shrink - allowing space within the vessel, blood can move past
Describe organisation and scarring?
Organised by fibroblasts causing scarring and reducing blood flow
Describe embolism?
Thrombus breaks off and moves passively through the circulation
What are the majority of emboli?
Fragments of thrombus
Other than fragments of thrombi what can embolism be made of?
Atheromatous debris, vegetations on heart valves, fat, tumours
Where do pulmonary embolisms occur?
Venous side - legs (deep vein thrombosis) and pelvic veins
How does the size of the embolus effect consequences of pulmonary embolisms?
Big = could block pulmonary artery = sudden death Small = smaller arteries = chest pain breathlessness, hypertension
Why does systemic embolism occur?
Thrombosis in left side of heart or aterial system
What do the consequences of systemic embolism depend on?
Size and site the thrombus lodges
What causes infarction?
Atheromas, thrombosis, embolism, vasculitis, compression, spasm, hyperviscosity
What determines infarction?
Vascular anatomy
Duration of occlusion (length of time the thrombus is there)
Metabolic requirements of tissue - brain has high requirements for glucose and oxygen - few minutes = death)
general circulatory factors - reduction in nutrients due tot heart failure
Reperfusion
What can cause aneurysms?
Atherosclerosis
Mycotic - infection
