Acute pulmonary embolism
RV dysfunction for risk stratification — and in shock, the bedside echo that justifies reperfusion.
Numbers to remember
- Suspected PE with shock: no RV dysfunction on echo practically excludes PE as the cause [124]
- McConnell sign: sensitivity 77%, specificity 94% in the original series [147]
- 60/60 sign: RVOT acceleration time <60 ms with TR gradient <60 mmHg [148]
- RV/LV basal diameter >1.0 and TAPSE <16 mm = RV dysfunction [124]
- TR gradient >60 mmHg suggests a chronic component (a normal RV cannot generate it acutely)
Questions echo must answer
Echo is not a diagnostic test for PE in stable patients. Its negative predictive value is too low [124]. It has three roles:
- Suspected high-risk PE (shock)If CT is not immediately possible, RV dysfunction on bedside echo justifies emergency reperfusion. Its absence practically excludes PE as the cause of shock [124].
- Risk stratification of confirmed PERV dysfunction on echo or CT combined with troponin defines intermediate-high risk [124].
- Complications and differentialsThrombus in transit, PFO (paradoxical embolism risk), and alternative causes of shock (tamponade, LV failure, dissection, hypovolaemia) [124,176].
Acquisition protocol
- Subcostal / A4CRV size relative to the LV (RV/LV basal diameter), RV free-wall motion (McConnell sign: mid free-wall akinesia with apical sparing) [124,147].
- PSAXD-shaped LV from septal flattening in systole and diastole; eccentricity index [166].
- RV functionTAPSE, S′, FAC [3].
- TR CWPeak gradient. A low or moderate gradient in a dilated, failing RV is typical of acute PE [148].
- RVOT PWAcceleration time; mid-systolic notching [148].
- IVCDilated with little collapse.
- Right heart sweepThrombus in transit in the RA or RV; PFO with colour or saline if clot is present [176].
- Lower limbsCompression ultrasound is part of the bedside approach [124].
- RV/LV ratio
- McConnell sign
- Septal flattening / D-sign
- TAPSE, S′
- TR gradient
- RVOT AcT and notching (60/60)
- IVC
- Right-heart thrombus
- Alternative diagnosis excluded
Diagnosis & severity
| Sign | Meaning |
|---|---|
| RV/LV basal diameter >1.0 | RV dilatation — risk marker [124] |
| TAPSE <16 mm | RV systolic dysfunction [124] |
| McConnell sign | Regional RV dysfunction; specific for acute PE (also seen in RV infarction) [147] |
| 60/60 sign | RVOT AcT <60 ms with TR gradient <60 mmHg: acute pressure load in an unconditioned RV [148] |
| Septal flattening | RV pressure overload (systolic and diastolic) [166] |
| Thrombus in transit | High-risk; urgent treatment [124] |
ESC 2019 risk classes [124]
- High: haemodynamic instability.
- Intermediate-high: PESI III–V or sPESI ≥1 with RV dysfunction on echo or CT and raised troponin.
- Intermediate-low: one or none of these.
- Low: PESI I–II or sPESI 0.
Thresholds that change management
- Shock + RV dysfunction on bedside echo, and CT not immediately available → treat as high-risk PE with systemic thrombolysis, or surgical or catheter-directed reperfusion if contraindicated [124].
- Shock without RV dysfunction → look for another cause [124].
- Intermediate-high risk → anticoagulation with close monitoring; rescue reperfusion if haemodynamics deteriorate. Routine full-dose thrombolysis is not recommended [124].
- Thrombus in transit or a PFO with clot straddling it → urgent multidisciplinary decision (thrombolysis versus surgical embolectomy) [124,176].
- 3–6 months after PE with persistent dyspnoea → echo for PH; if the probability is intermediate or high, V/Q scan to exclude CTEPH [8,124].
Pitfalls & mimics
PitfallA normal echo does not exclude PE in a stable patient. Use clinical probability, D-dimer and CT pulmonary angiography [124].
- RV infarction also produces a McConnell-like pattern. Check the ECG and inferior wall motion.
- Chronic PH (CTEPH, group 1): a thick RV free wall (>5 mm) and a TR gradient >60 mmHg point to a chronic process, or acute-on-chronic disease [8,148].
- RV-focused view differences: RV/LV ratio is view-dependent; measure at the base in end-diastole.
- Mechanical ventilation dilates the RV and raises the TR gradient in its own right.