Atherosclerosis, Thrombosis & Embolism

Define ‘Thrombosis’

Formation of a mass (thrombus) from the constituents of blood within the vasculature during life

How does a thrombus differ from a clot?

Thrombus must form during life in the body; clots can form when blood is extracted post-mortem

What are the 3 components of Virchow’s Triad?

Change in blood flow - Stasis

Changes in blood coagulability - Hypercoagulability

Endothelial Injury

What are some examples of hypercoaguable acquired states?

MI

Immobility

Cancer

Prosthesis

AF

Cardiomyopathy

Oral contraceptive use

Arterial thrombi are red

True/False?

False

Where do arterial thrombi’s often lodge?

Coronary, Cerebral, Femoral circulations

Define ‘embolism’

Detached intravascular solid/liquid/gas mass carried distal to point of origin

Venous emboli commonly infarct peripheral circulation

True/False?

False

Very rare (Carried to pulmonary circulation, more likely lodge there)

What are examples of factors that cause endothelial injury?

Smoking

HyperlipidemIa

Hypertension

Toxins

Infection

Give examples of what happens due to endothelial dysfunction

Increased permeability

Macrophage + Platelet adhesion & activation

Once macrophages are activated on the endothelial surface, What do they generate?

Oxidative free radicals

Cytokines

What do oxygen free radicals do to LDL?

Ingest & trap it within macrophages, forming foam cells/fatty streaks

In a pre-test probability (PTP) score for DVT, The scoring does not apply in what situations?

Previous DVT

Pregnancy

A PTP score of DVT of 3 or more is high risk

True/False?

True

D-diner can both rule out & diagnose DVT

True/False?

False

What is D-dimer?

A breakdown product of fibrin

If D-dimer levels are low, a DVT is unlikely

True/False?

True

If D-dimer levels are high, a DVT is very likely

True/False?

False

D-diners are raised by many things

E.g. Infection, MI, Surgery

If your PTP score is low & D-dimmers are low, A DVT can be excluded

True/False?

True

If your PTP score is low & D-dimmers elevated, What is the next investigation for diagnosing a DVT?

(Doppler) Ultrasound

If your PTP score is high & D-dimers low & US negative, DVT can be excluded

True/False?

True

If your PTP score is high & D-dimmers high but US negative, DVT can be excluded

True/False?

False

Repeat US before completely excluding DVT

What is the mainstay of DVT treatment?

Anticoagulation (LMWH Heparin, Warfarin)

TED compression stockings

What is phlegmasia dolens?

DVT causes obstruction of arterial flow due to back pressure created

How is phlegmasia dolens usually treated?

IVC filter through femoral artery which prevents thrombus entering lungs

What is the first line imaging modality of choice for PE?

V/Q scan

What is the advantage of a cabal filter for acute PE?

Prevents recurrence of PE in short term

What is the drawback of a caval filter?

Increases risk of DVT - patients will require anticoagulation if long-term filter

When is Warfarin contraindicated?

Pregnancy

Increased haemorrhage risk

(Uncontrolled drug abuse, Dementia etc.)