Obstruction of pulmonary arterial circulation, usually by deep venous thrombus.
Also known as: PE, pulmonary embolism, VTE, venous thromboembolism, saddle embolus, massive PE, submassive PE
Overview
Acute occlusion of one or more pulmonary arteries by thromboembolus, most commonly originating from a lower-extremity deep vein thrombosis. Severity ranges from incidental subsegmental PE to massive PE with hemodynamic collapse.
Epidemiology
VTE affects ~1-2 per 1000 adults annually. PE causes ~100,000 US deaths/year. Recurrence rate ~30% over 10 years without secondary prevention.
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Obesity, advanced age, smoking, long travel (>4 h)
Pathophysiology
Thromboembolus lodges in pulmonary arteries → mechanical obstruction + neurohumoral vasoconstriction → increased pulmonary vascular resistance. Right ventricular afterload rises; severe RV strain can cause hypotension, shock, and death. V/Q mismatch (perfusion of unventilated alveoli initially, then bronchoconstriction) → hypoxemia.
Musculoskeletal chest pain — Reproducible with palpation; normal vitals and oxygenation
Pericarditis/tamponade — Pleuritic pain improved leaning forward, diffuse ST elevation; pericardial effusion on echo
Anxiety/hyperventilation — Diagnosis of exclusion; normal ABG except respiratory alkalosis; no risk factors
Diagnostic workup
Diagnostic criteria
Confirmed PE on imaging. Use validated clinical decision rules: Wells score (low <2, moderate 2-6, high >6) or revised Geneva. PERC rule (8 criteria) can exclude PE in low-probability patients (<15%) without further testing.
Labs
D-dimer — sensitive but not specific; useful to rule out PE in low-probability patients (age-adjusted threshold: age × 10 ng/mL in patients >50)
Troponin and BNP — elevated in RV strain, prognostic (submassive PE)
ABG — hypoxemia, hypocapnia, widened A-a gradient (but normal in up to 20%)
CBC, BMP, INR/PTT before anticoagulation
Thrombophilia workup if unprovoked and young; defer testing until after acute treatment
Imaging
CT pulmonary angiography (CTPA) — gold standard if no contraindication
V/Q scan — alternative if CTPA contraindicated (renal failure, contrast allergy, pregnancy with low CXR yield)
Lower extremity Doppler — supportive when PE imaging contraindicated
Echocardiogram — RV dilation/dysfunction, McConnell sign (akinesia of RV mid-free wall with sparing of apex), pulmonary hypertension; useful for risk stratification not diagnosis
CXR — usually normal or nonspecific; helps exclude alternatives
flowchart TD
A[Suspected PE] --> B{Hemodynamically<br/>unstable?}
B -->|Yes| C[Bedside echo<br/>RV strain?]
C -->|Yes| D[Systemic thrombolysis<br/>or embolectomy]
B -->|No| E[Wells / Geneva<br/>pretest probability]
E -->|Low + PERC negative| F[PE excluded]
E -->|Low/Moderate| G[D-dimer<br/>age-adjusted]
G -->|Negative| F
G -->|Positive| H[CTPA]
E -->|High| H
H -->|Negative| I[Consider alternative dx]
H -->|Positive| J[Anticoagulation<br/>DOAC preferred]
Parenteral options: low-molecular-weight heparin (enoxaparin 1 mg/kg q12h) or unfractionated heparin (preferred if thrombolysis or surgery anticipated, renal failure, hemodynamic instability)
Hemodynamically unstable (massive PE — SBP <90 or vasopressor-dependent): systemic thrombolysis with alteplase 100 mg IV over 2 h
Catheter-directed thrombolysis or surgical/catheter embolectomy if contraindications to systemic thrombolysis or as alternative
Pregnancy: LMWH (does not cross placenta); avoid warfarin and DOACs
Second-line / adjunct
Duration: ≥3 months for provoked PE (transient risk factor); indefinite for unprovoked, recurrent, active malignancy, or persistent risk factors
Cancer-associated VTE: DOACs (apixaban, edoxaban, rivaroxaban) — non-inferior to LMWH (CARAVAGGIO, Hokusai-VTE Cancer trials); LMWH still preferred for GI/GU malignancies due to bleeding risk
IVC filter only if absolute contraindication to anticoagulation; remove when anticoagulation can resume
Submassive PE (RV dysfunction or troponin elevation, but no shock): risk-stratify; consider half-dose tPA or catheter-directed thrombolysis in select patients (PEITHO: thrombolysis reduced hemodynamic decompensation but NOT mortality, with increased major bleeding and stroke)
Outpatient management of low-risk PE (sPESI = 0, normal RV) is appropriate
Complications
Cardiogenic shock, cardiac arrest (PEA most common arrest rhythm)
Chronic thromboembolic pulmonary hypertension (CTEPH) — occurs in ~3% post-PE; treat with pulmonary endarterectomy (curative) or riociguat
Recurrence (~30% over 10 years without secondary prevention)
Bleeding from anticoagulation, including intracranial hemorrhage
Heparin-induced thrombocytopenia (HIT) with platelet drop >50%
PANCE pearls
PERC rule rules out PE without D-dimer in low-pretest-probability patients meeting all 8 criteria: age <50, HR <100, SpO2 >94%, no hemoptysis, no estrogen, no prior VTE, no recent surgery/trauma, no unilateral leg swelling.
Massive PE = hemodynamic instability; submassive = stable BP but RV dysfunction or troponin+; low-risk = stable, no RV strain. Risk-stratification (sPESI, PESI) drives disposition.
ECG findings of severe PE: S1Q3T3 (S in I, Q and inverted T in III), new RBBB, T-wave inversions in anterior leads. Sinus tach remains the most common ECG finding.
Wells criteria + age-adjusted D-dimer (age × 10 ng/mL if >50) safely reduce CTPA imaging in low-probability patients (ADJUST-PE).
DOACs are first-line for most non-pregnant patients with normal renal function; apixaban and rivaroxaban require no parenteral lead-in.
References
CHEST 2021 — Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report (Stevens et al., Chest 2021)
ESC 2019 — 2019 ESC Guidelines for the Diagnosis and Management of Acute Pulmonary Embolism (Konstantinides et al., Eur Heart J 2020)
PEITHO Trial — Fibrinolysis for Patients with Intermediate-Risk Pulmonary Embolism (Meyer et al., NEJM 2014)
ADJUST-PE — Age-Adjusted D-Dimer Cutoff Levels to Rule Out Pulmonary Embolism (Righini et al., JAMA 2014)
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