L13- Atheroma, Thrombosis & Embolism Flashcards Preview

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Flashcards in L13- Atheroma, Thrombosis & Embolism Deck (24):

What is Atherosclerosis ?

Degeneration of arterial walls characterised by fibrosis, lipid deposition and inflammation which limits blood circulation and predisposes to thrombosis


What are the Commonly affected vessels where atherosclerosis takes place?

Bifurcations (sites of turbulent flow)

Abdominal aorta

Coronary arteries

Popliteal arteries

Carotid vessels

Circle of Willis


What are the common risk factors for atherosclerosis?

Nonmodifiable: Age, gender, FH, genetics

Modifiable: Hyperlipidaemia, hypertension, diabetes, smoking


Pathophysiology of atherosclerosis

Arises due to chronic injury and repair of the endothelium

1) endothelial injury --> lipid will accumulate in the inner most part of the vessel (the “intima”)

2) Monocytes migrate into intima and ingest lipid becoming FOAM CELLS (fatty streak)

3) Foam cells secrete chemokines ---> atherosclerotic plaque develops as a result of cell proliferation

4) This mixture of fat, extracellular material and leukocytes and smooth muscle form the atherosclerotic plaque


Potential consequences of atherosclerosis?


Weakening of vessel walls
-Aneurysm formation

-Thrombosis formation


What is Thrombosis ?

Solidification of blood contents formed in the vessel during life


Clot vs Thrombus...

Clot: Stagnant blood, enzymatic process, elastic, adopts shape of vessel, stagnant blood

Thrombus: Dependent on platelets, firm, within the body during life


What are Platelets ?

Fragments of megakaryocytes in the bone marrow

Circulate in the blood stream

Bind to collagen exposed by endothelial damage and become activated

-Alpha granules: fibrinogen, fibronectin, PDGF
-Dense granules: chemotactic chemicals


Name the three parts of Virchow’s triad

Changes in :
-The intimal surface of the vessel
-The pattern of blood flow
-Blood constituents


Virchow's triad example of arterial thrombus...Name the changes happening:

Plaque rupture- turbulent flow and intimal change

Hyperlipidaemia – change in blood constituents

Platelets bind and fibrin is produced entrapping RBC


Where would Lines of Zahn be found?

Where thrombosis has occurred

Presence implies thrombosis at a site of rapid blood flow

E.g Aorta


Virchow's triad example of Venous Thrombosis...Name the changes happening:

Intimal change: valves

Change in blood flow: Immobile

Change in blood constituents:
-Inflammatory mediators (infection, malignancy)
-factor V leiden


What is Cardiac Thrombosis

Thrombi in the heart are known as mural thrombi and occur over areas of endomyocardial injury:

Can also occur with arrhythmias and cardiomyopathy


Potential Consequences of Thrombosis

Occlusion of vessel


Incorporation into vessel wall

Recanalisation (provides capillary-sized channels through the thrombus for continuity of blood flow)

Embolisation (thrombus breaks free from the vascular wall and becomes mobile)


What is an Embolus

A mass of material in the vascular system able to lodge in a vessel and block it


Most common emboli

Pulmonary emboli


Clinical effects of Pulmonary Emboli

Small: initially asymptomatic, if multiple may result in pulmonary hypertension

Medium: Cause acute respiratory and cardiac failure (V/Q mismatch, RV strain)

Large: Death “saddle emboli”
(It lodges at the main pulmonary arterial trunk at its bifurcation)


What do you call an infected aneurysm

Mycotic Aneurysm


What is an Infective embolism

Usually from the vegetations on infected heart valves

Effects compounded by the infective nature – may lead to mycotic aneurysm formation


What is a Tumour embolism

Bits may break off as tumours penetrate vessels

Do not usually cause immediate physical problems

Major route of dissemination


What is a Gas embolism

Air:(vessel opened into the air)
-Obstetric procedures / chest wall injury
>100ml to cause clinical effects

-Decompression sickness (“the bends”)
-Divers, tunnel workers
-Nitrogen bubbles enter bones, joints and lungs


What is an Amniotic fluid embolism

Increased uterine pressure during labour may force AF into maternal uterine veins

Lodge in lungs ---> respiratory distress


What is a Fat embolism

Microscopic fat emboli

Sudden onset of respiratory distress


What is a Foreign body embolism

Particles injected intravenously

E.g. talc in IVDU’s

Leads to a granulomatous reaction