Pulmonary embolism
Description
- Occlusion of pulmonary arteries, almost always by thrombus embolised from proximal lower-limb or pelvic DVT
- One end of the VTE spectrum - DVT and PE are the same disease
Classification - 2026 AHA/ACC clinical categories
*"Massive" and "submassive" are retired.* Five categories, graded by clinical severity, biomarkers, RV function and haemodynamics.
| Category | Definition |
|---|---|
| A | Asymptomatic/subclinical - incidental on CT for another reason |
| B | Symptomatic, low severity: PESI I-II, sPESI 0, or Hestia 0 |
| C1 | Elevated severity score (PESI III-V, sPESI >=1, Hestia >=1); normal troponin, no RV dysfunction |
| C2 | Elevated score + EITHER raised troponin OR RV enlargement/dysfunction |
| C3 | Elevated score + BOTH raised troponin AND RV dysfunction |
| D1 | Transient or recurrent hypotension - short-lived or fluid-responsive, no end-organ hypoperfusion |
| D2 | Normotensive shock - normal BP but raised lactate / AKI / hypoperfusion |
| E1 | Persistent hypotension with cardiogenic shock |
| E2 | Refractory cardiogenic shock (SCAI D-E) or cardiac arrest without ROSC after 30 min |
- Respiratory modifier "R" appended (e.g. C3R, D2R) when hypoxaemia, tachypnoea or supplemental oxygen requirement is present
- The old "submassive" bucket spanned everything from a mildly raised troponin to imminent collapse - C1 to D2 is the point of the new scheme
- ESC 2019 equivalents still widely used in Australia: low / intermediate-low / intermediate-high / high risk
Special forms
- Saddle PE - straddles the bifurcation; anatomical, not physiological - many are haemodynamically stable
- Subsegmental PE - often incidental; risk-benefit of anticoagulation genuinely uncertain in isolated subsegmental PE without DVT
- Non-thrombotic - fat (long bone fracture, 24-72 h, petechiae + confusion + hypoxia), amniotic fluid, air, tumour, septic (right-sided endocarditis, IVDU), talc, hydatid
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