Pathophysiology of Thromosis and Embolism

Question 1

What is stasis?

Answer 1

Stagnation of flow

Question 2

What is turbulence?

Answer 2

Forceful and unpredictable flow

Question 3

What are the main causes for defects in blood flow?

Answer 3

Thromboembolism, atheroma, hyperviscosity, spasm, external compression, vasculitis and vascular steal

Question 4

What are the three components of Virchow’s Triad?

Answer 4

Changes in the blood vessel wall, changes in the blood constituents and changes in the pattern of blood flow

Question 5

What does Virchow’s Triad represent?

Answer 5

The factors causing thrombosis

Question 6

What is thrombosis?

Answer 6

Formation of a solid mass from the constituents of blood within the vascular system during life

Question 7

What causes thrombosis?

Answer 7

Endothelial injury, stasis/turbulent blood flow and hypercoagulability of the blood

Question 8

What are lines of Zahn?

Answer 8

The alternating structure of RBCs and fibrin that form in a thrombus

Question 9

What factors does the consequences of the thrombosis depend on?

Answer 9

The site, extent and collateral circulation

Question 10

What are the common clinical presentations of thrombosis?

Answer 10

DVT, ischaemic limb and MI

Question 11

What are the outcomes of thrombosis?

Answer 11

Resolution, organisation/recanalization, death and propagation (embolism)

Question 12

What is an embolism?

Answer 12

Movement of abnormal material in the bloodstream and its impaction in a vessel, blocking its lumen

Question 13

What is an embolus?

Answer 13

A detached intravascular solid, liquid or gaseous mass

Question 14

What are the sources of systemic/arterial thromboembolus?

Answer 14

Mural thrombus (MI, left atrial dilation + AF), aortic aneurysms, atheromatous plaques and valvular vegetations

Question 15

Where can a systemic thromboembolus travel to?

Answer 15

Lower limbs (most common), brain and other organs

Question 16

What are the consequences of a systemic thromboembolus?

Answer 16

It depends on the vulnerability of the affected tissues to ischaemia, the calibre of the occluded vessel and the collateral circulation but usually infarction occurs

Question 17

Where does a venous thromboembolus originate from?

Answer 17

From deep venous thrombosis (lower limbs)

Question 18

Where do venous thromboemboli travel to?

Answer 18

The pulmonary arterial circulation

Question 19

What are the consequences of pulmonary thromboembolism?

Answer 19

They depend on the size but include: silent emboli, pulmonary haemorrhage/infarction, right heart failure and sudden death

Question 20

What effect does multiple PE have over time?

Answer 20

Pulmonary hypertension and right ventricular failure

Question 21

What are the risk factors for DVT and pulmonary thromboembolism?

Answer 21

Cardiac failure, severe trauma/burns, post-op/post-partum, nephrotic syndrome, disseminated malignancy, oral contraceptive, increasing age, bed rest/immobilisation, obesity and PMH of DVT

Question 22

What are the features of a fat embolus

Answer 22

It occurs after major fractures and it effects the brain, kidneys and skin

Question 23

What is the most likely cause for a gas embolus?

Answer 23

Decompression sickness - where nitrogen forms as bubbles which lodge in the capillaries

Question 24

When do air emboli often occur?

Answer 24

In head and neck wounds, surgery and CV lines

Question 25

What are the other forms of emboli?

Answer 25

Tumour, trophoblast, septic material, amniotic fluid, bone marrow and foreign bodies