Extracorporeal Life Support in Pulmonary Hypertension
Definition
Extracorporeal life support (ECLS) in pulmonary hypertension refers to the use of mechanical circulatory support devices — primarily veno-arterial ECMO (VA-ECMO) or pumpless PA-LA membrane oxygenators — to support the failing right ventricle in patients with advanced PH/PAH. The only established indication is bridge to transplantation in fully evaluated candidates. All other uses are investigational or reserved for highly selected cases.
Key Concepts
Devices and Technical Approaches
Peripheral Veno-Arterial ECMO
- Most widely used strategy; cannulation via femoral vessels (upper body approach for ambulation)
- ECMO flow 2.5–4 L/min achieves effective RV unloading while maintaining systemic perfusion without excessive increase in LV afterload (sources/PHT-RVsupport-WSPH-2019, rating: high)
- ECMO watershed: Two opposing blood flows in the aorta (from LV and ECMO) meet at a variable location determined by respective pressures/flows; lower body supplied by ECMO; upper body by native heart
- Clinical relevance: upper body oxygenation (brain, coronary arteries) depends on the oxygen content of blood from the LV — can be impaired if LV output is poorly oxygenated
- Monitor right forearm SpO₂ as surrogate for cerebral oxygenation; measure troponin and perform echocardiography regularly (sources/PHT-RVsupport-WSPH-2019, rating: high)
PA-LA Approach (Pumpless Membrane Oxygenator)
- Membrane oxygenator inserted between the pulmonary artery and left atrium; no pump required in PH because high pulmonary pressures provide the driving pressure gradient
- Requires sternotomy or anterolateral thoracotomy; temporary ECMO often needed before anaesthesia
- Advantages over VA-ECMO: ambulation is feasible (important for bridge-to-transplant fitness); oxygenated blood enters entire systemic circulation; increased LV preload "primes" the LV for post-transplant haemodynamics (sources/PHT-RVsupport-WSPH-2019, rating: high)
- Preferred when expected ECLS duration is prolonged or in children with small femoral arteries
Isolated RVAD
- Only sporadic case reports in PAH; no successful long-term use documented
- Pathophysiological risks: aggravation of pulmonary vascular remodelling from increased pulmonary blood flow; pulmonary haemorrhage; LV diastolic dysfunction → pulmonary oedema (LV is "unconditioned" in severe PH)
- Isolated RVAD should not be used in PAH (or used with extreme caution only) (sources/PHT-RVsupport-WSPH-2019, rating: high)
- Smaller devices with better pump flow control may open future options
Indications, Contraindications, and Timing
Established Indication
- Bridge to transplant: Patients who have been fully evaluated and accepted for lung transplantation with a realistic chance of receiving a donor organ in a reasonable time frame and who can still be expected to have a good outcome post-transplant (sources/PHT-RVsupport-WSPH-2019, rating: high)
Potential Indications (Highly Selected Cases Only)
- Bridge to transplant decision: Potentially eligible patients not yet fully evaluated who are deteriorating
- Bridge to recovery: Previously stable patients with a reversible cause of RV failure (arrhythmia, infection) or hitherto untreated/undertreated PAH — case reports of success exist but are rare (sources/PHT-RVsupport-WSPH-2019, rating: high)
Contraindication
- End-stage disease without a realistic chance for recovery or transplantation (futility) — ECLS in this setting is not appropriate; best supportive care is the correct approach
Timing
- Initiate when clinical course suggests imminent terminal RV failure or secondary organ failure despite optimised medical therapy
- ECLS during cardiopulmonary resuscitation for RV failure in advanced PH rarely results in good outcomes
- Use only when less invasive options have been exhausted
Awake ECMO Strategy
- ECMO in awake, non-intubated, spontaneously breathing patients is preferred when possible
- Avoids risks of general anaesthesia (high-risk in severe RV failure), mechanical ventilation (ventilator-associated pneumonia, muscle deconditioning)
- Feasibility demonstrated with bridging times of several weeks
- Associated with better outcomes than historical strategies involving intubation and mechanical ventilation (sources/PHT-RVsupport-WSPH-2019, rating: high)
Published Bridge-to-Transplant Outcomes
- 11 published series; 81 total patients (66 ECMO, 15 PA-LA); 77 used as bridge to transplant
- Rate bridged to transplant: 94% (72/77)
- Rate discharged from hospital: 78% (56/72)
- VA-ECMO and PA-LA both used effectively; no head-to-head RCT comparison (sources/PHT-RVsupport-WSPH-2019, rating: high)
Institutional Requirements
- Centres performing lung transplantation for PAH should have an established ECLS programme
- Interhospital transfer should be considered on an individual basis; some centres provide mobile ECLS units
Contradictions / Open Questions
- No RCT evidence for any ECLS strategy in PH: All recommendations are expert consensus from small, largely single-centre series. Optimal ECLS device choice, timing of initiation, and bridging strategy remain unvalidated by prospective trials (sources/PHT-RVsupport-WSPH-2019, rating: high)
- RVAD in PAH: Isolated RVAD is largely contraindicated, but smaller devices with better flow control represent a future investigational avenue not yet evaluated clinically
- Awake ECMO superiority: Observational data suggest better outcomes vs intubated bridging, but selection bias (healthier patients) confounds these comparisons
- Bridge to recovery: Success is documented only in rare case reports; patient selection criteria are not validated
Connections
- Related to concepts/Right-Ventricular-Failure — ECLS for refractory RV failure
- Related to concepts/Pulmonary-Hypertension — ECLS context within PAH management
- Related to concepts/Lung-Transplantation-PAH — ECLS as bridge to Tx and perioperative strategy
- Related to concepts/ECPELLA — combined ECMO + Impella for cardiogenic shock (different population)
- Related to entities/Vasopressin — vasopressor used concurrent with ECLS in PH