Atheroma and thrombosis Flashcards
define atherosclerosis
degeneration of arterial wall characterised by fibrosis, lipid deposition and inflammation which limits blood circulation and predisposes to thrombosis.
which vessels or positions on vessels are commonly affected by atherosclerosis.
Bi furcations (tubulent flow) Abdominal aorta Coronary arteries Popliteal arteries vessels in the leg Carotid vessels Circle of willis.
what are the common non modifiable risk factors of atheroscerlosis.
age, male, FH, genetics.
what are the common modifiable risk factors of atheroscerlosis.
Hyperlipidaemia (LDL:HDL) Hypertension Smoking Diabetes Other: CRP, ↑homocysteine,(metabolic condition)? Stress
what causes the atherosclerotic process to begin
chronic injury and repair of the endothelium
First step is endothelial injury.
what causes endothelial injury
Haemodynamic injury, chemicals, immune complex deposition, irradiation.
In which layer of the artery does lipid deposit in hyperlipademia.
intima
what factors are produced upon damage of the endothelium
adhesion factors.
what cells migrate to the intima engulfing lipid and forming foam cells
monocytes
what is the the name for the point at which monocytes engulf lipid and form foam cells
fatty streak.
what do the foam cell secrete to circulate more macrophages, lymphocytes and smooth muscle cells.
chemokines
what is the function of smooth muscle cells in the atherosclerotic plaque
proliferate and secrete connective tissue.
what forms the fibrous cap of a atheroscleotic plaque
smooth muscle, macrophages, foam cells, lymphocytes, collagen, elastin and proteoglycans.
what forms the necrotic centre of the atherosclerotic plaque
cell debris, cholesterol crystals, foam cells and calcium.
what pathology follows atherosclerosis
occlusion
weakening of vessel wall- aneurysm
erosion (of fibrous cap)- thrombus
define thrombus
Solidification of blood contents formed in the vessel during life.
what are the characteristics of a clot which make it different to a thrombus
stagnant
enzymatic process
elastic
adopt to the shape of the vessels
what are the characteristics of a thrombus which make it different to a clot.
during life
dependent on platelets
firm.
what cell is needed in thrombus formation
platelets.
what bone marrow cell gives rise to platelets
megakaryocytes.
what is the function of platelets, to what molecule do they bind in endothelial injury
circulate in the blood stream
Bind to collagen exposed by endothelial damage and become activated
what molecules do platelets secrete.
Alpha granules: fibrinogen, fibronectin, PDGF
Dense granules: chemotactic chemicals
how is virchow’s triad important in atherosclerosis formation
platelet adhesion and subsequent thrombus formation requires change in intimal surface of the vessel, blood flow and blood constituents.
what is the pathogenesis of arterial thrombosis
plaque ruptures- turbulent flow and intimal change.
Hyperlipidaemia- change in blood constituents.
Platelets bind and fibrin is produced entrapping RBC.
Thrombus propagation-infront of thrombus is laminar flow and behind thrombus is turbulent flow.
what is the pathogenesis of venous thrombosis.
intimal change- valves change in bloodflow immobile change in blood constituents- prothrombogenic Factor V leiden oestrogen inflammatory mediators
what are thrombi of the heart also known as
mural thrombi.
How does MI predispose the heart to thrombi
surface of the heart becomes sticky so the platelets adhere
How does arrhythmia’s predispose the heart to thrombi
stasis occurs and hence a thrombus can form.
what does a thrombus predispose you to
occlusion of a vessel resolution incorporation into the vessel recanalisation embolisation
define embolisation
A mass of material in the vascular system able to lodge in a vessel and block it
what are the acquired risk factors of pulmonary emboli
immobility, malignancy, previous VTE, heart failure, oestrogen’s, obesity, pregnancy, renal disease, smokers
what are the genetic and hereditary factors of pulmonary emboli
Thrombotic disorders
FV Leiden
Protein S defieiciency
what are the symptoms of DVT
looks hot, red swollen
what are the clinical symptoms of of small PE
asymptomatic, if multiple may result in pulmonary hypertension
what are the clinical symptoms of of medium PE
acute respiratory and cardiac failure (V/Q mismatch, RV strain)
what are the clinical symptoms of of large PE
“saddle emboli”
define paradoxical emboli
Hole in the heart means that clot can travel from the left to the right side of the heart and then lodge into a pulmonary vessel.
where do systemic emboli arise
in the heart or within the arterial circulation.
where do atheromas arise from
eroded plaques
where do platelet emboli arise from
atherosclerotic plaques.
where do infective emboli arise from
Usually from the vegetation’s on infected heart valves
what are the main causes of infective emboli
prosthetic valve and IV drug use.
consequence of infective emboli
mycotic aneurysm formation.
define tumour embolism
tumour section dislodges into blood vessel.
what are the 2 types of gas embolism
• Air (vessel opened into the air)
- Obstetric procedures / chest wall injury
• Nitrogen
– Decompression sickness (“the bends”)
– Divers, tunnel workers
– Nitrogen bubbles enter bones, joints and lungs
In an oxygen gas emboli what must the amount of oxygen be to cause significant effects
100 ml.
what causes amniotic fluid embolism- pathophysiology.
Increased uterine pressure during labour may force AF into maternal uterine veins
what causes fat embolism
significant trauma post menopause
what is a consequence of amniotic emboli
Lodge in lungs leading to respiratory distress
what is a consequence of fat embolism
Sudden onset of respiratory distress
what causes foreign body embolism
Particles injected intravenously
where do atheromas commonly form
lower limbs after and angiogram which can cause the plaque to dislodge.
define atheroma
Atheroma is a fatty deposit in the intima, which is the inner lining,
does atheroma predispose to atherosclerosis
Yes
