Atheroma (Pathophysiology) Flashcards
What is an atheroma?
A formation of focal elevated lesions in the intima of large and medium arteries
What is arteriosclerosis?
Agee related change to muscular arteries
Muscle hypertrophy and duplication of the IEL (fibrosis)
What does arteriosclerosis cause?
Cerebral, colonic and renal ischaemia in the elderly
What is the first stage of atheroma?
Fatty Streak
What follows the fatty streak?
Early atheromatous plaque
What follows the Early atheromatous plaque?
Fully developed atheromatous plaque
What follows the Fully developed atheromatous plaque?
Complicated atheroma
How does the fatty streak look like?
Yellow lipid-laden streak
What is contained within a fatty streak?
Masses of lipid-laden macrophages
What is contained within an atheromatous plaque?
Lipid core
Dead macrophage (foamy macrophages)
Extensive calcification
What are foamy macrophages?
Lipid laden macrophages containing oxidised lipoproteins
What is a complicated atheroma?
A FDAP with ruptured plaque leading to thrombosis
What causes the development of atheromatous plaque?
Endothelial damage with chronic inflammation
What changes to injured cells to increase the likelihood of atheroma formation?
Increased cell adhesion molecule expression
(ICAM-1, E-selectin)
Increased LDL permeability
What causes endothelial injury?
Turbulent flow
Hypercholesterolaemia
Increased free radicals
Growth factor release
What is the prevalence of hypercholesterolaemia in caucasians?
1/500
What are the signs of hypercholesterolaemia?
Family history of MI, atheroma
High blood LDL, HDL, total cholesterol
Corneal arcus
Xanthalasmata
What are biggest risk factors of atheroma?
Smoking Hypertension DM Male Age
Which plaques are most vulnerable?
Thin caps
Large lipid cores
Prominent inflammation
Primary prevention of atheroma
Smoking cessation Control BP Lose weight Exercise Diet control
Drug prevention of atheroma
Statins
Aspirin
Normal blood flow is what?
Laminar
What changes make up Virchow’s Triad?
Blood vessel wall
Blood constituents
Pattern of blood flow
What are Virchow’s triad?
Factors causing thrombosis
What is thrombosis?
Formation of a solid mass from the constituents of blood within the vascular system during life
What is the relationship between atheroma and thrombosis?
Arterial thrombosis most commonly superimposed on atheroma
What are the outcomes of thrombosis?
Resolution
Organisation
Recanalisation
Propagation
What is an embolism?
Movement of abnormal material in the bloodstream and its impaction in a vessel, blocking its lumen
What factors effect the consequences of systemic thromboembolus?
Size of occluded vessel
Collateral circulation
Where do venous thromboembolus most commonly travel to?
Pulmonary circulation
Multiple PE over time lead to what?
Pulmonary Hypertension
RVF
Risk factors for PTE, DVT?
Cardiac Failure Severe trauma Post-partum Nephrotic syndrome Malignancy Oral contraceptive Immobilisation Obesity PMH
Prophylaxis for surgical patients at risk of PTE/DVT
Compression stockings
Herparin
When can fat emboli occur?
After major fractures
What is effected by fat emboli?
Brain
Kidneys
Skin
When can cause gas emboli?
Air embolus
Decompression sickness
What causes air embolus?
Head and neck wounds
Surgery
CV lines
What is a trophoblastic emboli? Where does it effect?
Material from placenta
Lungs
What are the different types of embolus?
Fat Gas Tumour Bone marrow Foreign Bodies Amniotic Fluid Trophoblastic material Septic material
What are the presenting features of Rheumatic Fever?
Flitting polyarthritis of large joints Rashes Fever Pancarditis Heart Murmurs
Most common bacteria in Rheumatic fever?
Group A Beta-haemolytic streptococci
What are Aschoff bodies?
Foci of chronic inflammation, necrosis and activated macrophages
Seen in acute Rheumatic Fever
What is the most common cause of mitral regurgitation?
Ischaemic heart disease
What is hypoxic hypoxia?
Low inspired O2
(or) Low PaO2
What is anaemic hypoxia?
Abnormal blood with normal inspired O2
What is stagnant hypoxia?
Abnormal delivery
- local (occlusion)
- systemic (shock)
What is cytotoxic anaemia?
Tissue level disorder
Complicated atheroma in the coronary arteries leads to what?
Unstable angina
Ulcerated/fissured plaques of the coronary arteries lead to what?
Thrombosis –> MI
What is ischaemia?
Lack of blood supply to a tissue relative to demand, leading to hypoxia
What factors affect Oxygen supply to tissues?
Inspired O2 Pulmonary function Blood flow/constituents Integrity of vasculature Tissue mechanisms
What are the clinical presentations of ischaemia?
Cell dysfunction
Pain
Damage (specialised cells)
The scale of damage in infarction is dependent on what?
Duration
Tissue being cut off
Collateral blood supply
Previous disease
How long does ATP depletion take post MI?
Seconds
How long does loss of contractility take post MI?
<2 minutes
How long do reversible changes take post MI?
Minutes
How long do irreversible changes take post MI?
20-30 minutes
How long does myocyte necrosis onset take post MI?
20-40 minutes
How long does microvascular injury take post Infarct?
1hr
How long do swollen mitochondria take to appear post infarct (electron microscopy)?
3-12 hours
Where do pale infarcts occur?
Myocardium
Spleen
Kidney
Where do red infarcts form?
Loose tissues
Liver
Lung
How long does chronic inflammation/granulation tissue onset take post infarct?
72hrs
What are the end results of infarcts?
Scar
Reperfusion injury