1. Atheroma Thrombosis And Embolism Flashcards
What is an atheroma and what does it consist of
- Lesion in the intima that protrudes into a vessel wall
- soft core of lipid (mainly cholesterol and cholesterol esters)
- fibrous cap
What are foam cells
Macrophages that have engulfed lipid
What is the fibrous cap of an atheroma made up of
Macrophages, lymphocytes and foam cells and collagen and elastin
What is the necrotic centra of an atheroma made up of
Cell debris, cholesterol crystals, foam cells, calcium
What kind of vessels may be commonly affected by atherosclerosis
Bifurcation (normally sites of turbulent blood flow)
Abdom aorta
Coronary/ popliteal/ corotid arteries
Circle of Willis
Give three examples of non-modifiable risk factors of atheroma
Increasing age
Male gender
Family history
Give examples of modifiable risk factors for atheroma
Hyperlipidemia Hypertension Diabetes Smoking (Can damage the endothelium)
What are the main steps that lead to an atheroma
Response to injury hypothesis
- Damage/ injury to the inner layer of an artery (due to to diabetes or irritants such as nicotine
- Allows influx of cells and lipids into the intima
- Cells such as macrophages or smooth muscle cells often recruited from underlying media - try to engulf the lipids
- These become foam cells n die
- Excess of extracellular lipid
- Smooth muscle cells try to lay down collagen
- Form an overlying cap over this lipid pool
- Protrudes into the lumen of vessel
What is the primary cause of atherosclerosis developing
Endothelial injury to the arterial wall (leads to chronic inflammatory response)
What is the earliest lesions of atherosclerosis
Fatty streak
What is a fatty streak composed of
Lipid filled foamy macrophages - eventually collapse into streaks
Can be normal/common
Not significantly raised so dont cause flow disturbance
How is the atherosclerotic plaque formed
When the intima thickens - lipid accumulates
Appears white/ yellow raised plaques
Impinges on vessel lumen
Give 4 consequences of atherosclerosis
- Lesion could rupture, ulcerated, erode- integral surface is then exposed to blood, thrombogenic substances, induced thrombosis
- Heammorhage into plaque
- Atheromembolism
- Aneurysm formation (artery wall swelling) due to pressure, recruiting cells, chemical factors
What isa thrombus
Solid mass of blood constituents formed within the vascular system
What is venous thrombosis mostly due to
Stasis
What are the three factors in Virchow’s Triad
Endothelial injury
Abnormal blood flow (turbulence/ stasis)
Hypercoagulobility
What is claudication
Pain on walking due to reduced blood flow to legs
In which way is an arterial thrombosis mostly formed
From rupture of atheromatous plaque
Typical causes of venous thrombosis
Combination of factors from virchows triad
Why are venous sinusoids common locations of venous thrombosis
They allow pooling of blood
Is acute coronary syndrome caused by arterial of venous thrombosis
Arterial
Is claudication and ishchamic stroke caused by arterial or venous thrombosis
Arterial
What is the main composition of an arterial thrombus
Mainly platelets
Main composition of venous thrombus
Fibrin
What is the treatment for arterial thrombosis
Anti- platelet
Example of an anti platelet agent
Clopidogrel
Treatment for venous thrombosis
Anticoagulants eg warfarin heparin
What faactors can cause endothelial damage
Smoking
Hypertension
Surgery
Trauma
What are some heridtary factors that cause hypercogulobility
—Factor v Lieden (part of clotting cascade, resistant to cleavage by Protein C)
—Prothrombin G20210A (causes increased conversion of fribongen to fibrin)
—Protein C and S deficiency (cleave factors 5 and 8 which are brakes for the clotting cascade)
Give some exposes of acquired factors that cause hypercoagulobility
Cancer OCR/ HRT Pregnancy Obesity HIT = Heparin Induced Thrombocytopenia
Difference between clot n thrombus
Clot = settling of RBCs, hardened blood, can occur outside vessel (test tube/ haematoma) as well as inside (post-mortem) Thrombus = during life, occurs ONLY inside vessel
Are platelets involved in clot or thrombus
Only thrombus
What are lines of Zahn
Pale lines seen in a thrombus
Represent platelets and fibrin
Give some consequences of thrombosis
Occuslion of vessel Dissolution Incorporation into vessel wall -narrowing of lumen Recanalisation Embolisation
What’s an embolus
Mass of material in the vascular system able to become lodged in the vessel and block its lumen
What are emboli derived from
Mostly from thrombi
How are pulmonary emboli most commonly formed
Derived from DVT = thrombus in leg breaks off, goes through venous system to right side of heart, into pulmonary arteries
Where do systemic emboli arise from
Arterial system
What is a paradoxical embolus
Thrombus which arises in the venous system of the body and is able to travel into the heart, go through a septal defect into the left side and access the arterial circulation.
