ECMO for Saddle Pulmonary Embolism
Yes, ECMO can be used for saddle pulmonary embolism, but it should be reserved specifically for patients with refractory circulatory collapse or cardiac arrest, and should be combined with definitive reperfusion therapy (surgical embolectomy or catheter-directed treatment). 1
Clinical Context: Saddle PE Does Not Equal High-Risk PE
The presence of a saddle embolus on imaging does not automatically indicate hemodynamic instability or poor prognosis. Most patients with saddle PE are hemodynamically stable and respond well to standard anticoagulation alone. 2, 3
- In a community hospital series, only 8% of saddle PE patients had persistent shock, and mortality was 5.4% with standard heparin therapy 2
- The critical determinant for management is hemodynamic status, not radiographic clot burden 1
- Echocardiographic evidence of right ventricular dysfunction is present in 78-90% of symptomatic saddle PE patients, but this alone does not mandate aggressive intervention 2, 3
When ECMO Is Indicated
High-Risk (Hemodynamically Unstable) Patients
ECMO may be considered in combination with surgical embolectomy or catheter-directed treatment in refractory circulatory collapse or cardiac arrest. 1
Hemodynamic instability is defined as: 1
- Sustained hypotension (systolic BP <90 mmHg for ≥15 minutes)
- Requiring inotropic support
- Pulselessness
- Persistent profound bradycardia (HR <40 bpm with shock)
ECMO as Bridge Therapy
- Venoarterial ECMO optimizes end-organ function as a bridge to recovery or definitive intervention 1
- Case reports demonstrate successful VA-ECMO use in saddle PE with cardiac arrest, even in patients with advanced malignancy and brain metastases, with successful weaning within 72 hours 4
- VA-ECMO can facilitate large-bore catheter embolectomy by stabilizing the patient during the procedure, resulting in rapid hemodynamic improvement 5
Treatment Algorithm for Saddle PE
Step 1: Assess Hemodynamic Status
Hemodynamically Stable (BP ≥90 mmHg, no shock):
- Initiate therapeutic anticoagulation with DOAC (apixaban 10 mg q12h × 7 days or rivaroxaban 15 mg q12h × 21 days) 1
- Monitor closely for deterioration 1
- Do not use thrombolysis or ECMO 1
Hemodynamically Unstable (High-Risk PE):
- Immediate IV unfractionated heparin with weight-adjusted bolus 6
- Systemic thrombolysis is first-line therapy 1, 6
- Consider norepinephrine and/or dobutamine for hemodynamic support 6
Step 2: If Thrombolysis Fails or Is Contraindicated
- Surgical pulmonary embolectomy is recommended (Class I recommendation) 1
- Catheter-directed therapy should be considered as alternative (Class IIa recommendation) 1
- ECMO may be considered in combination with these interventions (Class IIb recommendation) 1
Step 3: ECMO Implementation Considerations
When ECMO is used: 1
- High bleeding risk is a contraindication to ECMO (requires anticoagulation)
- Clot location matters: proximal clots respond better to endovascular therapy and surgical embolectomy 1
- ECMO should not be used as standalone therapy—it must be combined with definitive clot removal 1
Critical Pitfalls to Avoid
- Do not initiate ECMO based solely on radiographic appearance of saddle embolus 2, 3
- Do not use ECMO in hemodynamically stable patients, even with RV dysfunction on echo 1, 2
- Recognize that ECMO causes acquired von Willebrand syndrome (loss of high-molecular-weight multimers) within hours, increasing bleeding risk 1
- Ensure multidisciplinary team involvement (PE response team) for high-risk and selected intermediate-risk cases 1
- Remember that deteriorating respiratory status (not just hemodynamic status) may prompt immediate intervention 1
Special Populations
Cancer patients with saddle PE: