Deep vein thrombosis and plumonary embolism Flashcards Preview

Cardiovascular System > Deep vein thrombosis and plumonary embolism > Flashcards

Flashcards in Deep vein thrombosis and plumonary embolism Deck (29):
1

What is a 'clot' made up of?

- Fibrin
- Platelets
- Red blood cells

2

How is a clot formed?

Damage to endothelium etc > Tissue factor > X reacts with Prothrombin to produce Thrombin > Thrombin reacts with Fibrinogen to produce Fibrin which reacts with factor XIII to produce cross-linked fibrin

3

Mechanisms in Arterial vs Venous thrombosis

Arterial
- Usually rupture of atherosclerotic plaque

Venous
- Combination of Virchow's triad, especially stasis and hypercoagulability

4

Location of origin in Arterial vs Venous thrombosis

Arterial
- Arteries, left heart chambers

Venous
- Venous valves and venous sinusoids of muscles

5

Results in Arterial vs Venous thrombosis

Arterial
- Ischaemia and infarction

Venous
- Back pressure

6

Disease in Arterial vs Venous thrombosis

Arterial
- Acute coronary syndrome
- Ischaemic stroke
- Limb claudication/ischaemia

Venous
- Deep vein thrombosis
- Pulmonary embolism

7

Composition in Arterial vs Venous thrombosis

Arterial
- "white thrombus"
- Platelets and fibrin

Venous
- "red thrombus"
- Red blood cells and fibrin

8

Features of Virchow's Triad

- Stasis
- Hypercoagulability
- Endothelial damage

9

What is an embolism?

Intravascular material that migrates from its original location to a distal vessel
E.g. blood clot, fat, air, tumour

10

What is a thromboembolism?

Movement of blood clot along a vessel

11

Examples of venous thromboembolism (VTE)

- Limb deep vein thrombosis (DVT)
- Pulmonary embolism (PE)

- Visceral venous thrombosis
- Intracranial venous thrombosis

12

Epidemiology of venous thromboembolism

- DVT: 1 in 1000 patients
- PE: 1 in 3000-5000 patients
- Leading cause of direct maternal death in UK
- Case fatality rate: 1 to 5% - untreated PE: 30%
- PE in 20% of autopsies

13

Risk factors for VTE

- Major abdominal/pelvic surgery
- Hip/knee replacement
- Late pregnancy
- Fracture
- Malignancy
- Congenital heart disease
- Hypertension
- COPD
- Obesity

14

Symptoms and signs of DVT

- Unilateral limb swelling
- Persistent discomfort
- Calf tenderness

- Warmth
- Redness-erythema
- Prominent collateral veins
- Unilateral pitting oedema

May be clinically silent!!

15

What is a potential long-term consequence of DVT?

Post Thrombotic Syndrome
- Damage to venous valves
- Incidence of 20-60% within 2 years of DVT

- Swelling
- Discomfort
- Pigmentation
- Ulceration in severe form

16

Diagnosis of DVT

- Clinical assessment and pretest probability score (Wells score)

- Blood test: D-dimer if low pre-test probability score

- Imaging: compression ultrasound if positive D-dimer or high pre-test probability score

17

Learn wells score for DVT

kinda know about it

18

What is a D-Dimer?

- Breakdown product of cross-linked fibrin: produced during fibrinolysis
- High sensitivity for VTE
- Low specificity for VTE: trauma, malignancy, sepsis, bleeding, cancer, recent surgery

19

How is a D-Dimer formed?

Plasmin combines with Fibrin producing fibrin degradation products (FDPs), including D-dimer

20

Symptoms and signs of pulmonary embolism

- Pleuritic chest pain
- Breathlessness (dyspnoea)
- Blood in sputum (haemoptysis)
- Rapid heart rate (tachycardia)
- Pleural rub on auscultation: usually due to pulmonary infarction

21

Symptoms and signs of massive pulmonary embolism

- Severe dyspnoea of sudden onset
- Collapse
- Blue lips and tongur (cyanosis)
- Tachycardia
- Low blood pressure
- Raised jugular venous pressure
- May cause sudden death!!

22

Diagnosis methods of pulmonary embolism

- Clinical assessment and pretest probability score (Wells score or Geneva score)
- Blood test: D-dimer if low pre test probability score
- Imaging: If D-dimer positive or high pre test probability score: Isotope ventilation/perfusion scan, CT pulmonary angiogram

23

Look over Wells score for PE

Do it

24

What is a potential long-term consequence of pulmonary embolism?

- Pulmonary arterial hypertension
- Most recover fully

25

What is the aims of treatment of VTE?

- Prevent clot extension
- Prevent clot embolisation
- Prevent recurrent clot

26

What are the treatment options for VTE?

Anticoagulation is the main treatment
- Parental options: unfractionated heparin, low molecular weight heparin
- Enteral options: warfarin, direct oral anticoagulants (DOACs)

Thrombolysis is reserved for massive PE: e.g. Alteplase

27

Prevention methods of VTE in hospital

- Early mobilisation
- 'Anti-embolism stockings' - help with the flow of blood
- Other mechanical methods of thromboprophylaxis
- Pharmacological thromboprophylaxis

28

Summary learning outcomes

- VTE is common and deadly
- Aim to prevent VTE in patients at significant risk
- Need to be aware of suggestive symptoms and signs
- Apply diagnostic and treatment pathway

29

How do you develop a pulmonary infarction after a PE?

Pulmonary infarction = rare due to dual vascular supply to lungs with anastomoses
- Blockage to a branch of the pulmonary artery = increase in pressure within pulmonary vasculature

- Force within bronchial artery may be insufficient to overcome this

- 'Leakage' of blood into alveolar space occurs, and leads to infarction