L13- Atheroma, Thrombosis & Embolism Flashcards Preview

EMS- mod > L13- Atheroma, Thrombosis & Embolism > Flashcards

Flashcards in L13- Atheroma, Thrombosis & Embolism Deck (24):
1

What is Atherosclerosis ?

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

2

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

3

What are the common risk factors for atherosclerosis?

Nonmodifiable: Age, gender, FH, genetics

Modifiable: Hyperlipidaemia, hypertension, diabetes, smoking

4

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

5

Potential consequences of atherosclerosis?

Occlusion
-Ischaemia

Weakening of vessel walls
-Aneurysm formation

Erosion
-Thrombosis formation

6

What is Thrombosis ?

Solidification of blood contents formed in the vessel during life

7

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

8

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

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

9

Name the three parts of Virchow’s triad

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

10

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

11

Where would Lines of Zahn be found?

Where thrombosis has occurred

Presence implies thrombosis at a site of rapid blood flow

E.g Aorta

12

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
-Oestrogen

13

What is Cardiac Thrombosis

Thrombi in the heart are known as mural thrombi and occur over areas of endomyocardial injury:
-M.I
-Myocarditis

Can also occur with arrhythmias and cardiomyopathy

14

Potential Consequences of Thrombosis

Occlusion of vessel

Resolution

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)

15

What is an Embolus

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

16

Most common emboli

Pulmonary emboli

17

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)

18

What do you call an infected aneurysm

Mycotic Aneurysm

19

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

20

What is a Tumour embolism

Bits may break off as tumours penetrate vessels

Do not usually cause immediate physical problems

Major route of dissemination

21

What is a Gas embolism

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

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

22

What is an Amniotic fluid embolism

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

Lodge in lungs ---> respiratory distress

23

What is a Fat embolism

Microscopic fat emboli

Sudden onset of respiratory distress

24

What is a Foreign body embolism

Particles injected intravenously

E.g. talc in IVDU’s

Leads to a granulomatous reaction