Venous Thromboembolism - Pulmonary Embolism

Question 1

Definition

Answer 1

DVT embolisms and lodges in pul. Artery circulation

Question 2

Risk factors

Answer 2

Recent surgery (esp abdominal/pelvic or hip/knee replacement)
Thrombophillia
Leg fracture
Prolonged bed rest/reduced mobility
Malignancy
Pregnancy/post partum, combined contraceptive pill
Previous PE

Question 3

Aetiology

Answer 3

Usually arise from venous thromboembolism in the pelvis or legs. Clots break off and pass through the veins + right side of heart before lodging in pulmonary circulation
Rare causes:
- RV thrombus (post MI)
- Septic emboli (right sided endocarditis)
- Fat, air or amniotic fluid embolism
- Neoplastic cells
- Parasites

Question 4

Pathophysiology

Answer 4

Once a thrombus has developed it can travel (embolism) from the deep veins, through the right side of the heart, into the lungs where it becomes lodged in the pulmonary arteries
This can lead to cor pulmonale -> increased pulmonary vascular resistance -> increased RV strain to overcome this -> RVH -> RV fails second at to increased pulmonary artery pressure
If a patient has a septic defect - the blood can pass through the right side of heart into systemic circulation. If it travels to the brain = stroke

Question 5

Signs

Answer 5

Small emboli may be asymptomatic
Large emboli are often fatal:
- pyrexia
- cyanosis
- tachypnoea
- tachycardia
- hypotension
- raised JVP
- pleural rub
- pleural effusion
-

Question 6

Symptoms

Answer 6

Patient Sx - sudden onset pleuritic chest pain, dyspnoea (+/- haemoptysis) with evidence of DVT e.g. swollen calf + immobilisation Hx
Acute breathlessness
Pleuritic chest pain
Haemoptysis - streaky blood on coughing
Dizziness
Increased JVP
Syncope
Ankle oedema

Question 7

Diagnosis

Answer 7

Wells score (PE) > 4 = likely PE (e.g. DVT evidence = 3pts, Tachycardia = 1.5 pt)
If 4+ = Immediate CTPA (GOLD STANDARD)or treat empirically if delay (LMWH)
If <4 = Do d-dimer (1st line)
- d-dimer +ve = CTPA
- d-dimer -ve = consider alternative diagnosis
ECG = sinus tachycardia S1Q3T3 - pathognomonic - major sign of cor pulmonale
T wave inversion of anterior + inferior leads = most specific finding
New RBBB
CXR = Normal

Question 8

Treatment

Answer 8

If massive PE (hypotensive < 90 systolic = THROMBOLYSIS -> ALTEPLASE (“clot buster”)
If non massive PE (mostly) =
Anticoagulation (DOAC)
* 1st line = APIXIBAN/RIVAROXABAN
* CI (renal impairment) = LMWH

Question 9

Differential

Answer 9

Pneumothorax, Pneumonia all present with PLEURITIC CHEST PAIN
DDx = CXR
- In PE = normal
- Pneumonia + pneumothorax = DIAGNOSTIC

Question 10

VIRCHOWS TRIAD

Answer 10

HYPER COAGULABILITY
- Preggo, COCP, obesity, antiphospholipid syndrome, sepsis, DIC, malignancy
VENOUS STASIS
- Immobility (long flights, after surgery) = typically spread out clotting factors - laminar flow; stasis -> aggregation of clotting factors
ENDOTHELIAL INJURY
- smoking, trauma/surgery
- normally secretes anticoagulant chemicals, damaged endo CANNOT!