Thrombosis, Embolism and Pulmonary Hypertension Flashcards
What is the difference between a thrombus and a clot?
Thrombus- inside vessel
Clot- outside vessel
Where is thrombosis favoured according to Virchow’s triad?
Stasis (turbulent blood flow), endothelial injury and hypercoagulability
What can cause a hypercoagulable state?
Malignancy, pregnancy, hormone replacement, bowel disease, sepsis
What can cause endothelial injury?
Venous disorders, valve damage, trauma, surgery, catheters
What can cause stasis?
LV dysfunction, immobility, venous insufficiency/obstruction, pregnancy, obesity
What two things must happen for a thrombus to form?
Platelet activation and fibrin production
What does activating platelets do?
Makes them stickier so they aggregate more platelets and fibrin
What is the end point of the coagulation cascade?
Aggregation of fibrin
What is the first stage of thrombus formation?
Endothelial injury which exposes collagen
What happens in the formation of a thrombus after collagen has been exposed?
Collagen and Von Willebrand factor bind to glycoproteins on platelets which increases platelet integrins
What do glycoproteins on platelets bind with?
Fibrinogen
Describe the intrinsic coagulation pathway?
Hageman factor and Kallikrein through factors XII, IX, VIII
What is the extrinsic coagulation pathway?
Tissue factor binding with factor VII
What is the common pathway of coagulation?
Activated Factor IIa then through X, V, II
What happens after the common pathway of coagulation?
Factors II and XIII activate fibrinogen to fibrin
What type of vitamin is vitamin K and where is it stored?
Fat soluble in the liver
What does vitamin K produce?
Clotting factors II, VII, IX and X
What competes with vitamin K?
Warfarin
What is plasmin?
Clot buster
What are anti-clotting factors?
Protein S, protein C and antithrombin II
What causes inherited disorders of coagulibility?
Protein C/S/antithrombin II deficiency or Factor V Leiden
Why are thrombi less common in arteries?
High flow blood moves pro-coagulant material away quickly
When is the only occasion that thrombosis occurs in arteries?
Atherosclerosis
Why are sites where vessels branch more common?
More turbulent blood flow
Where is stasis common?
Depp veins, faulty valves and venous insufficiency
Where do the biggest PEs tend to come from?
Femur
Most emboli are thrombi, what else could they be?
Gas, fat, foreign bodies, tumour clumps
Pulmonary emboli are an important cause of what?
Sudden death and pulmonary hypertension
Where is the source of most PEs?
Deep vein thrombosis
What is ischaemia?
Insufficient blood flow
What is infarction?
Tissue death as a result of ischaemia
What do large emboli cause?
Death, infarction, severe symptoms
What do small emboli cause?
Pulmonary hypertension but clinically silent
What is pulmonary infarction?
Compromised blood and oxygen causes lung tissue to die
How does a DVT present?
Hot, swollen, red, tender calf or whole leg
What is the 1st line scan for DVT?
Ultrasound Doppler leg scan
What is the 2nd line test for DVT?
CT of ileo-femoral vein, IVC and pelvis
How will a large PE present?
CV shock, low BP, central cyanosis, sudden death
How will a medium PE present?
Pleuritic pain, haemoptysis, breathless
How will a small PE present?
Progressive dyspnoea, pulmonary hypertension, right sided heart failure
What are risk factors for PE?
Thrombophilia, contraceptive pill, pregnancy, pelvic obstruction, trauma, surgery, immobility, malignancy, vasculitis, obesity
What are clinical features of PE?
Tachycardia, tachypnoea, cyanosis, fever, low BP, crackles, rub, pleural effusion
What will ABGs for PE show?
Low O2- type 1 respiratory failure
What will a CXR of PE show?
Normal early on, may show a wedge shaped infarct
What is the gold standard test for PE?
CTPA
What is the 2nd line scan for PE which is good in pregnancy?
V/Q scan
What is a useful rule out test for PE?
D-dimers
What are some ways a DVT can be prevented?
Compression stockings, early post-op mobilisation calf muscle exercise, anticoagulants
What are PEs treated with and for how long?
Anticoagulation with LMWH or warfarin for 3 months is provoked and longer if not
What is the treatment for large life threatening PEs?
Thrombolysis
What are interactions of thrombolysis?
Alcohol, antibiotics, aspirin, NSAIDs, grapefruit
What can post-thrombotic syndrome cause?
Pain, oedema, hyperpigmentation, eczema, varicose veins, ulceration
What is the relative flow/pressure in the pulmonary circulation?
High flow, low pressure
What is classed as pulmonary hypertension?
> 25mmHg
What can cause pulmonary venous hypertension?
Ischaemia, stenosis, cardiomyopathy
What can cause pulmonary arterial hypertension?
Hypoxia, multiple PE, vasculitis, drugs, HIV, left to right shunt
What is cor pulmonale?
Right sided heart failure secondary to lung disease
What are signs of cor pulmonale?
Central cyanosis, oedema, raised JVP, right ventricular heave
What are probably the most important tests for Cor Pulmonale?
ECG, CXR, ABGs, echo
How is primary pulmonary hypertension diagnosed?
By ruling out other causes
What is the typical presentation of pulmonary hypertension?
SOB on exertion and signs of right sided failure
What is treatment for primary pulmonary hypertension?
Pulmonary vasodilators and lung transplant
