AKT · Cardiovascular/Vessels, aorta & venous

Pulmonary embolism

Thrombus (usually from a leg DVT) lodging in the pulmonary arterial tree

Overview

Obstruction of the pulmonary arteries, usually by an embolised leg DVT. It ranges from small subsegmental clots to massive PE with obstructive shock. The two-level PE Wells score directs CTPA vs D-dimer; massive PE with haemodynamic instability is an indication for thrombolysis. Anticoagulation with a DOAC is first-line for the stable patient.

Recognise

Pleuritic chest pain, breathlessness, haemoptysis, tachycardia, tachypnoea, hypoxia; signs of a DVT
Massive PE: hypotension/shock, syncope, signs of right heart strain
ECG: sinus tachycardia (commonest); classic but uncommon S1Q3T3; right heart strain

Red flags

Massive PE with haemodynamic instability (hypotension/shock) → thrombolysis (or embolectomy)
PE in pregnancy → senior/obstetric input; D-dimer unhelpful, image appropriately

Differentials & how to tell them apart

Acute coronary syndrometerritorial ECG/troponin; less hypoxia

Pneumonia / pleurisyfever, consolidation, productive cough

Aortic dissectiontearing pain, pulse asymmetry

Anxiety/hyperventilationnormal oxygenation, no risk factors — a diagnosis of exclusion

Investigations

Two-level PE Wells: likely → CTPA (V/Q if contraindicated); unlikely → D-dimer, CTPA only if positive. ECG and CXR (exclude alternatives); ABG; troponin/echo for right heart strain in severe PE; assess bleeding risk before thrombolysis.

Management

Stable → DOAC (apixaban/rivaroxaban); massive PE with shock → thrombolysis

1Apply the two-level PE Wells score: likely → CTPA; unlikely → D-dimer, then CTPA only if positive. Give oxygen and start anticoagulation while awaiting imaging if delay is expected.Gate: Massive PE with haemodynamic instability (hypotension/shock) → thrombolysis (alteplase), not just anticoagulation — this is the decision that changes management.
2Stable PE → DOAC (apixaban/rivaroxaban) first-line for ≥3 months; extend for unprovoked/cancer-associated PE and investigate for an underlying cause.

DOAC first-line (apixaban/rivaroxaban) — for the haemodynamically stable patient; LMWH/warfarin if DOAC unsuitable

Thrombolysis (alteplase) for massive PE — haemodynamic instability/shock — the indication that changes management; surgical/catheter embolectomy if thrombolysis contraindicated/fails

Oxygen + haemodynamic support — supportive; cautious fluids in RV failure

Duration ≥3 months — extended for unprovoked/cancer; investigate cause if unprovoked

Key points

Pleuritic chest pain + breathlessness + hypoxia + tachycardia → two-level PE Wells: likely = CTPA, unlikely = D-dimer first. Stable → DOAC. Massive PE with hypotension/shock → THROMBOLYSE. Sinus tachycardia is the usual ECG; S1Q3T3 is classic but rare.

Monitor & prognosis

Oxygenation/haemodynamics, right heart function in severe PE, anticoagulation and duration.

Good when treated promptly; massive PE has high early mortality.

Source: NICE NG158 (VTE); cross-ref acute_care