thrombosis and anticoagulation

Question 1

arterial circulation vs venous circulation

Answer 1

arterial circulation: high pressure: platelet rich

venous circulation: low pressurefibrin rich

Question 2

where are the main areas of an arterial thrombosis?

Answer 2

Coronary circulation
Cerebral circularion
Peripheral circulation
Other territories

Question 3

Arterial thrombosis - etiology

Answer 3

Atherosclerosis
Inflammatory
Infective
Trauma
Tumours
Unknown - platelet deriven

Question 4

Arterial thrombosis - Presentations

Answer 4

coronary artery - IM/ACS - chest pain
cerebral artery - stroke/TIA
Peripheral artery - 6Ps
Others such as renal

Question 5

Arterial thrombosis: coronary treatment + mnemonic

Answer 5

ALTeR
- Aspirin + antiplatelets
- LMWH / Fondraparinux
- Thrombolytic therapy (dissolves clot)
- Reperfusion (PPI)

Question 6

how do thrombolytic therapies work and what are the types?

Answer 6

• streptokinase
• tissue plasminogen activator
  breaks down clots by generating plasmin which degrades fibrin

Question 7

Arterial thrombosis: cerebral treatment

Answer 7

aspririn + antiplatelet
thrombolysis
reperfusion
(same as coronary but no heparin because inc risk of hemorrhage)

Question 8

Arterial thrombosis: treatment - other sites (not coronary and cerebral)

Answer 8

Antiplatelets, statins
Role of anticoagulants evolving
Endovascular vs Surgical

Question 9

Venous thrombosis common areas

Answer 9

Peripheral:
- Ileofemoral
- femoro-popliteal

Other sites:
– Cerebral, Visceral

Question 10

Venous thrombosis-diagnosis

Answer 10

• Signs and symptoms-very non-specific
• Blood tests –D-dimer –sensitive but not specific(protein rleased to break down clots) - if high could suggest clot or clotting disorder
• Imaging-usually required eg ultrasound or MRI

Question 11

what image techniques are usually conducted to diagnose venous thrombosis?

Answer 11

• ultrasound with doppler - detects blood flow and visualises clots
• CT/MRI venography - die injected into veins so they can be visualised using an imaging technique

Question 12

Venous thrombosis-aetiology

Answer 12

Virchows triad:
blood flow - statuent or slow
endothelium injury - could clot
blood constituents / hypercoagulation - genetic, cancer, hormones

Surgery
Immobilisation
Oestrogens: OC, HRT
Malignancy
Long haul flights
genetic conditions
acquired conditions

Question 13

Venous thrombosis -genetic (5)

Answer 13

Factor V Leiden (5%)
PT20210A (3%)
Antithrombin deficiency
Protein C deficiency
Protein S deficiency

Question 14

Venous thrombosis-acquired

Answer 14

Anti-phospholipid syndrome:
- autoimmune
- produces antibodies that target proteins that bind to phospholipids - inc risk of clotting

Lupus anticoagulant:
- type of antiphospholipid antibody that interferes with normal clotting cascade

Hyperhomocysteinaemia:
- high levels of homocytesine - risk factor for clotting

Question 15

Venous thrombosis-treatment

Answer 15

Heparin or LMWH
Warfarin
DOAC - direct oral anticoagulant

Endo-vascular / Surgical procedures eg catheter-directed thrombolysis (CDT), thrombectomy, and stenting

Question 16

Venous thrombosis-prevention

Answer 16

Mechanical or chemical thromboprophylaxsis
mechanical:
- compression socks
- inflation cuffs that promote blood flow
- LMWH + DOAC

Also early mobilisation and good hydration

Question 17

Heparin

Answer 17

• Glycoaminoglycan
• Binds to antithrombin and increases its activity
• Indirect thrombin inhibitor

Monitor with APTT, aim ratio 1.8-2.8 (monitors the time taken to clot - assesses heparin effecacy)

Given by continuous infusion in hospital setting

Question 18

Low molecular weight heparin

Answer 18

• Smaller molecule, less variation in dose and renally excreted
• Once daily, weight-adjusted dose given subcutaneously
• Used for treatment and prophylaxsis (prevention of blood clots)
• longer half life
• can be administered at home and last up to 24hrs

Question 19

Warfarin

Answer 19

• Orally active
• Prevents synthesis of active factors 2, 7, 9, 10
• Antagonist of vitamin K
• Long half life (36 hours)
• Prolongs the prothrombin time
• Difficult to use,
• Individual variation in dose
• Need to monitor
• Measure INR (international normalised ratio, derived from prothrombin time)(measures how long it takes blood to clot)
• Usual target range 2-3,
• Higher range 3-4.5

Question 20

Aspirin

Answer 20

Inhibits cyclo-oxygenase irreversibly
Act for lifetime of platelet, 7-10 days
Inhibits thromboxane formation and hence platelet aggregation
Used in arterial thrombosis, 75-300 mg od

Question 21

Other antiplatelets

Answer 21

Clopidogrel -inhibits ADP induced platelet aggregation by irreversibly binding to the p2y12 receptors
Ticagrelor – p2y12 receptor antagonist
Prasugrel – p2y12 receptor antagonist

Question 22

magnitude of DVT

Answer 22

25,000 people a year die of DVT and PE a year in UK
50% preventable, premature mortality
More than RTA, AIDS and breast cancer combined

Question 23

Risk factors for DVT

Answer 23

Surgery, immobility, leg fracture/ POPOC pill, HRT, PregnancyLong haul flights/ travel (rare)Inherited thrombophilia- genetic predisposition; 5% population, familial

Virchows Triad

Question 24

DVT diagnosis

Answer 24

Symptoms: leg pain, swelling
Signs: tenderness, swelling, warmth, discolouration
Phlegmasia - severe swelling and pain in the leg
PE

Question 25

DVT investigation

Answer 25

- D-dimer: normal excludes diagnosis - positive does not confirm diagnosis (non-specific) - Ultrasound compression - visualise flow and clots - CT / MR venogram - catheter venogram - injecting dye to visualise

Question 26

DVT treatment

Answer 26

LMW Heparin s/c od for min 5 days Oral warfarin, INR 2-3, (2.5) for 3-6 months DOAC/NOAC Compression stockings – symptoms vs PTS Treat/ seek underlying cause: malignancy, thrombophilia, compression Spontaneous vs provoked

Question 27

Re-cannalisation

Answer 27

removing the clot: Endovenous Chemical Mechanical - d Mechanico-chemical Stents

Question 28

Prevention of DVT

Answer 28

Mechanical- hydration and early mobilisation, Compression stockings, Foot pumps Chemical- LMW Heparin

Question 29

Thromboprophylaxsis

Answer 29

Low risk: <40 yrs, surgery < 30 mins: early mobilisation and hydration, no chemical, TED if surgical High risk: hip and knee, pelvis, malignancy, risk factors, prolonged immobilityAll immobile medical, many surgical/ O+G Daltrparin s/c od. No monitoring

Question 30

Pulmonary Embolism symptoms

Answer 30

breathlessness, pleuritic chest pain, may have signs/ symptoms of DVT, may have risk factors, no other diagnosis more likely

Question 31

Pulmonary Embolism signs

Answer 31

tachycardia, tachypnoea, pleural rub, those of precipitating cause, none of alternative diagnosis

Question 32

Pulmonary EmbolismCommon presentation

Answer 32

Differential diagnosis of chest pain and sob Consider also musculoskeletal, infection, malignancy, pneumothorax, cardiac, gastro causes

Question 33

PE initial investigations

Answer 33

CXR usually normal ECG sinus tachy, (QI,SI,TIII) Blood gases: type 1 resp failure, decreased O2 and CO2 Mainly done to exclude alternative causes

Question 34

PE Further investigations

Answer 34

D-dimer: normal excludes diagnosis CTPA or spiral CT - visualise segmental thrombi Ventilation/ Perfusion scan: mismatch defects

Question 35

Treatment PE

Answer 35

Supportive treatment LMW Heparin s/c od weight adjusted 5/7 Oral warfarin INR 2-3 (2.5) for 6 months DOAC Treat underlying cause

Question 36

Prevention of PE

Answer 36

Early mobilisation and hydration Mechanical Chemical IVC filters

Question 37

Pulmonary Embolism -Massive

Answer 37

Hypotension, cyanosis, severe dyspnoea, right heart strain/ failure Rare Consider Catheter mechanico-chemical thrombectomy or surgical thrombo-embolectomy Haemodynamic instability

Question 38

Describe the pathophysiology of arterial thrombosis and how it differs from venous thrombosis.

Answer 38

Arterial thrombosis involves clots in arteries caused by plaque rupture, leading to conditions like heart attacks, while venous thrombosis forms clots in veins due to slow blood flow, often resulting in conditions like deep vein thrombosis.

Question 39

contrast heparin with LMWH

Answer 39

heparin - larger molecule - IV or subcutaneous - lasts 1-2hrs - required frequent monitoring (aPPT) LMWH - smaller molecule - subcutaneous - lasts 4-6 hours - can be done at home - no monitoring

Question 40

DVT clinical assessment

Answer 40

Tap test (Schwartz) Trendelenburgh test SFJ Incompetence Tourniquet test Perforator Incomp SPJ Incomp Perthes test Deep venous Incomp

Question 41

DVT Investigation

Answer 41

Duplex Gold standard MRV Pelvic Venography Pelvic

Question 42

Treatment – Superficial Venous Disease

Answer 42

Lifestyle Compression Sclerotherapy Endo-venous treatments Surgical stripping

Question 43

Treatment – Deep Venous Disease

Answer 43

Lifestyle Compression Stents Valves