Question 5

a)    Define massive pulmonary embolism.    (10% marks)

b)    Discuss the advantages and disadvantages of thrombolysis, catheter directed clot removal and surgical embolectomy, in the treatment of massive pulmonary embolism.    (90% marks)


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College answer

Not available.


a) Massive  (or "high risk") PE is defined by the AHA guidelines (2011) as:

  • SBP <90 mmHg for at least 15 minutes;
  • OR requiring inotropic support,
  • AND not due to a cause other than PE, pulselessness, or persistent profound bradycardia.


  Advantages Disadvantages
  • Widely available
  • Use is supported by major society guidelines (AHA 2011, ESC 2019)
  • Reduces the risk of death by as much as 55%
  • Minimally invasive (requires a PIVC)
  • Does not require sedation or anaesthesia
  • Substantial risk of lifethreatening bleeding, including ICH
  • Risk of bleeding is probably underestimated by clinical trial data
  • May not work in patients who present following a substantial delay (as the clot has started to organise)

Catheter-directed clot removal

  • Excellent published success rate (~87%), i.e. achieved improvement of hypoxia, haemodynamic stability, and survival
  • Lower risk as compared to systemic thrombolysis
  • May be performed in patients in whom thrombolysis was not completely effective or is contraindicated
  • Can be offered concurrently with antigoagulation
  • Minimally invasive, as compared to surgical embolectomy
  • Can be repeated several times, or thrombolysis can be administered continuously for a sustained period
  • Data regarding efficacy is mainly derived from registries and pooled results from case series
  • Concern re. publication bias and industry sponsorship
  • Requires interventional radiology, which may not be widely available
  • Invasive
  • Substantial radiation and IV contrast exposure
  • May require sedation or an anaesthetic, which could be dangerous in the haemodynamically unstable patient
  • Still may not work in patients who present following a substantial delay (as the clot has started to organise, and would be less friable)
Surgical embolectomy
  • Highly effective even for clots which have become organised
  • Can be offered concurrently with antigoagulation
  • May be an option for patients in whom thrombolysis is contraindicated
  • Outcomes are at least as good as thrombolysis, and rates of rethrombosis or intervention are reduced (mortality rate only 12%) 
  • Cannot be offered to patients who have recently received thrombolysis
  • Maximally invasive and requires anaesthetic plus cardiopulmonary bypass
  • Recovery is prolonged in comparison to other methods
  • Rarely performed, which means staff may be deskilled
  • Only available at centres where cardiothoracic surgery is routinely performed