Pathophysiology of Thrombosis and Embolism Flashcards by Chloe Lee

What is a term to describe normal blood flow?

Laminar - travels smoothly and in regular paths

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What are two abnormal blood flow patterns?

Turbulence

Statis

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What is static blood flow?

Stagnation of blood flow - occurs due to occlusion

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What is turbulent blood flow?

Forceful, unpredicatable flow

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What are the causes of abnormal blood flow?

Thromboembolism

Atheroma
Hyperviscosity 
Spasm 
External compression
Vasculitis 
Vascular steal

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What is vascular steal?

Dilation of one vascular network (e.g., during exercise or vasodilator therapy) “steals” blood flow from another region within the organ that is already maximally dilated because of the presence of proximal lesions

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What are the factors of Virchow’s Triad?

Changes too blood vessel wall
Changes in the blood constituents
Changes in the pattern of blood flow

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What is Virchow’s Triad?

Factors causing thrombosis

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What is thrombosis?

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

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Give an example of change that can occur in the vessel wall?

Atheromatous coronary artery

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What are three changes that occur that lead to thrombus formation?

Endothelial injury
Stasis or turbulent blood flow
Hypercoagulability of the blood

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What is the difference between a thrombus and a clot?

A thrombus forms within the vascular system during life

A clot can occur anywhere and postmortem in the vascular system it is called a clot

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Describe the stages of thrombosis

Atheroma causes turbulent blood flow
Loss of intimal cells from denudation of the plaque
Platelet adhere to exposed collagen
Forms fibrin network and trapped RBCs
Lines of Zahn appear
Causes further turbulence and platelet deposition
Leads to propagation

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What can cause changes to the vessel wall?

MI - can lead to mural thrombosis in the heart

Turbulent flow - denuding intima

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What changes can occur to blood constituents?

Dehydration
Hyperviscosity
Post-traumatic hypercoagubility
Polycythaemia (increased Hb)

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What can causes changes to blood flow (i.e. cause stasis or turbulence)?

Stasis: post-op (bed bound), long flights sitting down
Turbulence: atheromatous plaque, aortic aneurysm

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What is a mural thrombosis?

Blood clot on the wall of the heart

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What does the consequences of thrombosis depend on?

Site
Extent
Collateral circulation

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List some clinical consequences of a thrombosis?

DVT, ischaemic limb, MI

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What are favourable outcomes of thrombosis?

Resolution

Organisation and recanalisation

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What are bad outcomes of thrombosis?

Death

Propagation -> embolism

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What is an embolism?

Movement of abnormal material in the bloodstream and its impaction in a vessel, occluding it

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What is an embolus?

Detached intravascular solid, liquid or gaseous mass

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Difference between thrombosis and embolism

Thrombosis occurs when a thrombus develops in a blood vessel and reduces blood flow
Embolism occurs when a piece of thrombus, foreign object, or other bodily substance becomes stuck in a blood vessel, occluding it

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What are most emboli substances?

Dislodged thrombi - thromboembolism

What are some of the sources of thrombi in the arterial system?

Mural thrombus (MI, LA dilatation and AF) Aortic aneurysms Atheromatous plaque Valvular vegetations (from growth of bacteria)

What is paradoxical emboli?

An embolus which is carried from the venous side of circulation to the arterial side, or vice versa. I.e. valvular vegetations (from vv. to aa.)

Where can systemic thromboemboli travel to in the body?

Lower limbs (common) Brain Other organs

What do the consequences of a systemic thromboembolism depend on?

Vulnerability of affected tissues to ischaemia Calibre of occluded vessel Collateral circulation but usually infarction occurs

What is the most common form of thromboembolic disease?

Venous thromboembolus - originates from deep venous thromboses (lower limb)

Where do venous thromboemboli travel to?

Pulmonary arterial circulation Depending on size, may occlude main pul. artery, bifurcation of trunk or small arteries

What is a saddle embolus?

A large pulmonary thrombo-embolism that straddles the main pulmonary arterial trunk at its bifurcation

What are the consequences of a pulmonary thromboembolism?

``` Depends on size: Silent Pulmonary haemorrhage/infarction RHF Sudden death ```

What can multiple PEs lead to over time?

Pulmonary HPT | R ventricular failure

What are the risk factors for DVT an pulmonary thromboembolism?

``` Cardiac failure Severe trauma/burns Post-op/post-partum Nephrotic syndrome Disseminated malignancy Oral contraceptive Age Bed bound/immobilisation Obesity PMH of DVT ```

What is the management for surgical patients for prophylaxis from DVT and pul. thromboembolism?

TEDS stockings | Heparin (anticoagulant)

When are patients at risk of a fat embolism?

After major fracture

What do fat embolism affect?

Brain Kidneys Skin

When are patients at risk of a gas embolism?

Decompression sickness - N2 forms as bubbles which lodge in capillaries

When are patients at risk of an air embolism?

Head and neck wounds After surgery CV lines

List other types of embolus

``` Tumour Trophoblast (pregnant women - lungs) Septic material (infective endocarditis) Amniotic fluid Bone marrow (fracture i.e. CPR) Foreign bodies ```

What is a septic material embolism?

Embolism that is infected with bacteria, resulting in the formation of pus

What is an amniotic fluid embolism?

Amniotic fluid enters the blood stream of the mother which causes cardiorespiratory collapse and massive bleeding (coagulopathy)

What is a bone marrow embolism?

Fat tissue from the bone marrow can occlude vessels

List the type of forge in bodies which can cause an embolism

Intravascular cannulae tips | Sutures

What is rheumatic fever?

An inflammatory disease that can involve the heart, joints, skin, and brain, sometimes neurological symptoms

Where is rheumatic fever prevalent?

India Middle East Central Africa and now Europe and North America

What individuals does rheumatic fever commonly affect?

5-15 yrs | Boy > girls

What does rheumatic fever present with?

'Flitting' (painful) polyarthritis of large joints (wrist, elbows, knees, ankles) Skin rashes or nodules Fever

What occurs in the acute phase of rheumatic fever?

Pancarditis (inflammation affecting endocardium, myocardium and pericardium) Heart murmurs common Aschoff bodies

What inflammatory bodies form in the heart in rheumatic fever?

Aschoff bodies

What are Aschoff bodies composed of?

Chronic inflammatory cells Necrotic mycoses Activated macrophages (anitfchkow cells)

What are three types of valvular heart disease

Stenosis Regurgitation/incompetence Vegetation

What is valvular stenosis?

Valve thickened/calcified and obstructs normal blood flow into chamber/vessel

What is valvular regurgitation?

Valve loses normal function and fails to prevent reflux of blood after contraction of cardiac chambers

What are valvular vegetations?

Infective or thrombotic nodules develop on valve leaflets impairing normal valve mobility and may embolise

What is pancarditis in acute rheumatic fever cause over time?

Progresses over time to chronic rheumatic heart disease, manifesting as valvular abnormalities

How does pancarditis lead to formation of small valvular vegetations?

Inflammation of endocardium and L sided valves causes fibrinoid necrosis of the valve cusps/chordae tendinae (and along line of valve closure)

What is a main feature of rheumatic heart disease?

Deforming fibrotic valvular disease (esp mitral valve) Leaflet thickening Commissural fusion and shortening Thickening and fusion of chord tendinae

What is the (virtually) only cause of mitral stenosis?

Rheumatic heart disease

What valvular diseases does rheumatic heart disease cause?

``` Mitral stenosis Mitral regurgitation Aortic stenosis (rare) Aortic regurgitation Tricuspid valve and pulmonary valve involvement rare ```

Pathophysiology of Thrombosis and Embolism Flashcards

(61 cards)