MOD 13 - Atherosclerosis and embolism Flashcards
definition of atherosclerosis
degeneration of arterial walls characterised by fibrosis, lipid deposition and inflammation which limit blood circulation and predisposes to thrombosis
what are the commonly affected arteries
bifurcations (sites of turbulent flow), abdominal aorta, coronary arteries, popliteal arteries, carotid vessels, circle of willis
risk factor for atherosclerosis
age, male, FH, genetics, hyperlipidaemia (LDL:HDL), hypertension, smoking, diabetes, CRP, stress
what is the first step in the road to atherosclerosis
endothelial injury (arises due to chronic injury and repair of the endothelium) - haemodyanmic injury , chemicals, immune complex deposition, irradiation
how is atheroma formed
- endothelial injury
- hyperlipidaemia (lipid deposit in intima by the recognition of scavenger receptors which recognise LDL)
- monocytes migrate into intima (lipid and endothelial injury) to ingest lipid forming ‘foam cell’ - fatty streak
- foam secrete chemokines
- attract more monocytes, lymphocyes & smooth muscle cells
- smooth muscle cells proliferate and secrete connective tissue
- mixture of fat, extracellular material and luekocytes and smooth muscle form the atherosclerotic plaque
what is the constituent of atherosclerotic plaque
fat, extracellular material, leukocytes, smooth muscle
what is atheromatous plaque
progression of atherosclerotic plaque
fibrous cap (smooth muscle cells, macrophages, foam cells, lymphocytes, collagen etc), necrotic center, media
what is the structure of the atheromatous plaque
shoulder, cap, core
what will happen to the atherosclerosis
grow larger, occlusion of the arteries, weakening of vessel walls (aneurysm formation), erosion (thrombosis)
what is thrombosis
solidification of blood content formed in the vessel during life
what are the difference between thrombosis and a clot
thrombus - within the body during life, dependent on platelets, firm
clot - stagnant blood, enzymatic process, elastic, adopts shape of vessels
what does the platelet adhesion and subsequent thrombous require according to virchow’s triad
intimal surface of the vessel, pattern of blood flow, blood constituents
how does arterial thrombus form
normal - atheroma (change in flow) - ulceration (loss of endothelial cells) - platelet adherence to the ulcerative site - thrombus formation
what can cause cardiac thrombosis
arrhythmias and cardiomyopathy
what is the sequelae of thrombosis
occlusion of vessel, resolution, incorporation into vessel wall, recanalisation, embolisation
what is embolus
a mass of material in vascular system able to lodge in a vessel and block it - can be endo or exogenous, maybe solid, liquid or gas
what is the most common embolism
pulmonary emboli
risk factor for venous thromboembolism
immobility, malignancy, previous VTE, heart failure, oestrogens, obesity, pregnancy, renal disease, smokers, thrombotic disorder (FV leiden)
what are some of the effect of venous thromboembolism
small - asymptomatic (if multiple can result in pulmonary hypertension)
medium - cause acute respiratory and cardiac failure
large - death - saddle emboli
what is the common cause of infective embolism
usually from vegetations on infected heart valves - can lead to aneurysm formation
what is tumour embolism
bits breaks of as tumours penetrate vessels
what can cause gas embolism
air - vessel opened into the air
nitrogen - decompression sickness eg divers, tunnel workers
what is amniotic fluid embolism
Increased uterine pressure during labour may force AF into maternal uterine veins
what is fat embolism
microscopic fat embolism found in 80% of patients
