pathological thrombosis

Question 1

3 main causes of thrombus

Answer 1

1. Changes in the intimal surface of a vessel
2. Changes in the pattern of blood flow
3. Changes in the blood constituents
   these 3 predisposing situations that may result in thrombus formation are known as Virchow’s triad

Question 2

smoking cigarettes

Answer 2

increases the stickiness of platelets and they find it easier to aggregate. This makes it more likely that a thrombosis occurs in any vessel in the body (but isn’t a definite cause). This alteration in the properties of blood is a change in blood constituents which is part of Virchow’s triad.

Question 3

what are 2 predisposing factors of arethoma in coronary arteries

Answer 3

cigarette smoking

high lipid diet

Question 4

arethoma

Answer 4

disease of the coronary arteries
results in a build up of lipid under the intimal surface
this can result in abnormal blood flow - slow and turbulent

Question 5

slowed blood flow predisposes to

Answer 5

fibrin and platelet clumping

Question 6

wall damage in coronary arteries

Answer 6

lipid and collagen can rupture through the intimal surface

platelets and fibrin are now exposed to an abnormal substance and turbulnt flow and are deposited as a thrombus

Question 7

how does a thrombus in the coronary artery lead to a clot

Answer 7

the thrombus blocks the lumen of the coronary artery

clot forms in the stagnant blood behind the thrombus

Question 8

lines of Zahn

Answer 8

the multiple alternating layers of thrombus and clot

Question 9

Virchow’s triad in coronary artery thrombosis

Answer 9

1. Changes in the intimal surface of the vessel: atheroma lipid coming onto surface
2. Changes in blood flow pattern: bulge of atheroma changing the blood flow
3. Changes in blood constituents: smoking making it more likely that platelets aggregate
   - All 3 situations may occur and lead to coronary artery thrombosis

Question 10

partial obstruction of a coronary artery

Answer 10

decreased flow beyond the blockage, the tissue supplied by this artery receives less blood flow
□ If it is severe enough, ischaemia leads to decreased oxygenation of tissues
□ The tissue is said to be ischaemic
□ Ischaemic heart tissue is often painful

Question 11

ischaemia

Answer 11

reduced blood flow to a tissue

Question 12

hypoxia

Answer 12

decreased oxygenation of tissues

Question 13

complete obstruction of coronary artery

Answer 13

no flow beyond the blockage
□ Lack of blood flow (ischaemia) leads to severe lack of oxygen and a localised area of tissue dies –> infarct

□ The process of tissue dying in any manner is called necrosis.

Question 14

define infarct

Answer 14

necrosis as a result of ischaemia (ischaemic necrosis)

localised area of dead tissue in a living person, consequent upon ischaemia

Question 15

other locations of infarcts

Answer 15

Coronary artery thrombosis - infarct in heart
Cerebral artery thrombosis - infarct in brain
Mesenteric artery thrombosis - infarct in gut

Question 16

define embolism

Answer 16

A mass of material moving in the vascular system and able to become lodged in a vessel and block its lumen

Question 17

most emboli are derived from

Answer 17

thrombi or clots

they break off and move elsewhere in the circulation

Question 18

thromboembolism

Answer 18

when thrombi/clots emolise

commonest example = pulmonary embolism

Question 19

pulmonary embolism

Answer 19

○ Sluggish flow in leg veins leads to thrombosis and clot formation
Part of the thrombus (and clot) breaks off and travels up vein
○ Embolus passes into inferior vena cava, then right heat, then pulmonary trunk and lodges in pulmonary artery branch
Embolus blocks pulmonary artery and get pulmonary infarct

Question 20

other forms of embolism

Answer 20

○ Fracture a leg: marrow enters ruptured vein, marrow embolises to blood vessels = marrow embolism
○ Knife wound to neck: air enters vein, air embolises to heart = air embolism