DVT And Pulmonary Embolism

Question 1

What is meant by the following terms:
- Pulmonary embolism (PE)
- Venous thromboembolism (VTE)

Answer 1

• Pulmonary embolism - obstruction of one or more pulmonary arteries by embolised venous thrombus
• VTE - encompasses DVT and PE

Question 2

Describe the aetiology of PE.

Answer 2

• Embolism - process by which bloodstream carries deteached thrombus from point of origin to distant site
• Most PEs originate as thrombi due to DVT

Question 3

What are some other causes of PE?

Answer 3

• Fat embolism
• Air embolism
• Amniotic fluid embolism
• Septic emboli
• De novo thrombosis (rare)

Question 4

Describe the pathophysiology of PE.

Answer 4

• V/Q mismatch → impaired gaseous exchange → hypoxaemia (type 1 respiratory failure) and tachypnoea
• Pulmonary arterial hypertension (due to increased pulmonary vasculature resistance) → right ventricular overload +/- dysfunction
• Pleural and lung inflammation and infarction → pleuritic chest pain +/- haemoptysis

Question 5

List 3 risk factors for PE.

Answer 5

• Diagnosis of DVT: ~45-50% of people with PE have concurrent DVT
• Increasing age
• Previous VTE

Question 6

What are the 3 elements of Virchow’s triad and for each element, give example of scenarios that can give rise to VTE?

Answer 6

• Venous stasis: prolonged immobilisation (e.g. bed rest >5 days, major surgery within the last 2 months, recent trauma or fracture, paralysis of the lower limb, long-haul flights), venous insufficiency of the lower limb.
• Hypercoagulable state: active malignancy, pregnancy and postnatal period, thrombophilia (e.g. antiphospholipid syndrome, factor V Leiden mutation), use of combined hormonal contraception and oral HRT
• Endothelial injury: trauma, surgery, venous harvest, cigarette smoking, obesity.

Question 7

What symptoms might be indicative of PE when taking a history from a patient?

Answer 7

• Dyspnoea: the most common feature
• Tachypnoea (~20-40% cases)
• Pleuritic chest pain (~40% of cases)
• Features of concurrent DVT (typically unilateral red, painful swollen leg)
• Haemoptysis
• Retrosternal chest pain (due to RV ischaemia)
• Cough

Question 8

What symptoms might be indicative of PE when examining a patient?

Answer 8

• Tachycardia
• Tachypnoea
• Hypoxia
• Low-grade fever
• Pleural rub
• Gallop rhythm, a wide split-second heart sound and tricuspid regurgitant murmur.

Question 9

What are some features of massive pulmonary embolisms?

Answer 9

• Haemodynamic instability: hypotension and cardiogenic shock
• Presyncope/syncope
• Elevated jugular venous pressure (JVP)

Question 10

What beside investigation should be done during PE and what possible findings would there be?

Answer 10

• 12-lead ECG - always done in context of chest pain. Only used to exclude differential diagnoses - not diagnostic of PE
• Sinus tachycardia: the most common finding
• Right ventricular strain pattern: T wave inversion in anterior leads (V1-V4) +/- inferior leads (II, III, aVF)
• Right bundle branch block (RBBB)
• Right axis deviation (RAD)
• ‘S1Q3T3’ ECG change is only seen in <20% patients – large S wave in lead I, large Q wave in lead III, and inverted T wave in lead III

Question 11

What lab investigations can be done for potential PE?

Answer 11

• D-dimer levels: often raised, typically >500 ng/mL
• Full blood count (FBC): may demonstrate leucocytosis due to acute inflammation but is non-specific
• Urea and electrolytes (U&E)
• Liver function tests (LFTs
• Coagulation studies: should be established before starting treatment and can guide treatment.

Question 12

What conditions can also lead to raised D-dimer in absence of VTE?

Answer 12

• Pregnancy
• Malignancy
• Liver disease
• Severe infection/inflammatory disease
• DIC patients
• Recent trauma/surgery patients