Mechanical Circulatory Support: Bridging Strategies

OVERVIEW

CERC 05 was privileged to hear directly from the team at the Queen Elizabeth Hospital Birmingham, one of the UK's leading cardiac transplant centres. Mr Aaron Ranasinghe and Dr Sern Lim shared their real-world experience with both surgical and percutaneous MCS strategies, offering practical insights into device selection, surgical technique, complication management, and post-operative care.

Together, the presentations offered a comprehensive framework for MCS decision-making relevant to teams managing complex advanced heart failure in New Zealand.

Part 1: Surgical BiVAD - Bridge to Transplant

• UK heart transplant waiting list has three tiers: Super-Urgent, Urgent, and Non-Urgent

• Super-Urgent = adult patients on any temporary VAD or ECMO (including LVAD, BiVAD, Impella, VA-ECMO); excludes IABP 

• Super-Urgent patients receive highest donor priority: first locally, then nationally in time order; median wait on support 15 days

• Choice of MCS device directly determines transplant access tier in the UK system

• Patient Selection for Surgical BiVAD:

  • (1) Urgent-listed patients on the ward on inotropes who decompensate - urgent BiVAD implant

  • (2) Cardiogenic shock patients on ECMO/Impella (bridge to bridge) who require longer-term RV support

• RV assessment is critical: no validated scoring system; experienced echo-based judgment, right heart pressures, and TAPSE used - ultimately an experienced multidisciplinary decision

• Prefer BiVAD over LVAD when: recurrent VT (risk of RV failure with LVAD during VT), significant RH dysfunction, or need for definitive biventricular support

• Surgical BiVAD Technique (CentriMag):

  • CentriMag pumps: RA → PA (RVAD circuit) and LV → Aorta (LVAD circuit)

  • Cannulas: 34Fr drainage, EOPA return cannulas; tunneled subcutaneously through the chest wall

  • Operative sequence: sternotomy → patient placed on central VA-ECMO using the eventual BiVAD cannulas → heart elevated → LV cannula placed at apex (aimed toward mitral valve) → PA cannula placed → 'switcheroo' (all circuits reconnected to CentriMag pumps)

  • LV cannula: ring of pledgets into LV apex; aimed toward mitral valve for optimal drainage; confirmed on X-ray and CT

  • Aortic return: via 10mm Dacron graft snugged to ascending aorta (formal anastomosis done by some surgeons)

  • Gore-Tex pericardial membrane placed at closure — facilitates future transplant re-entry

  • Cannula tunneling: standardised routing (same as chest drains) so nursing staff always know which cannula is which

• Complications and Troubleshooting:

  • Mobile LV thrombus: standard apex cannulation contraindicated; solution: place LA drainage cannula via Sondergaard's groove (left atrium to LVAD) to avoid thrombus embolism and PA reconstruction issues

  • Fresh infarct tissue: sewing quality concerns; cannulation may be challenging

  • Septal defects: small PFO acceptable; larger defects need repair before or during BiVAD implant

  • Aortic insufficiency: needs addressing (significant AR would cause LV distension on LVAD)

  • Flow challenges: patient is own reservoir; aggressive volume loading required; severe pulmonary oedema can prevent left-sided flow - temporary solution: remove PA cannula, Y-join RA and LV drainage → central VA-ECMO with large LV vent; reconnect PA cannula once oedema resolves

• Post-Operative Management:

  • Anticoagulation: no heparin for 24+ hours post-implant (high flows reduce clot risk); convert to warfarin longer term to reduce HIT risk

  • Full mobilisation: patients walk around ICU with BiVAD hardware; outdoor access; physiotherapy essential

  • Pump exchange: manufacturer IFU advises pump change at 30 days; QEB have not routinely changed pumps for many years without adverse consequence. Longest support duration at QEB: 134 days; Papworth Hospital (UK) has supported for 9 months

  • Post-transplant: higher rates of vasoplegia expected; short-term post-transplant ECMO may be needed for blood pressure support

• Outcomes:

  • Attrition: approximately 1 in 3 patients bridged to BiVAD do not reach 90-day post-transplant: factors include multi-organ failure, bleeding, sepsis before transplant availability

  • For patients who reach transplant: UK data shows outcomes equal to or slightly better than standard heart transplant cohort (likely due to peak donor organ allocation)

  • Bridge to recovery: very rare with surgical BiVAD - primarily used as bridge to transplant; myocarditis exception (two early cases recovered)

  • If recovery is possible, preference is now percutaneous approach (easier explant)

Part 2: 'Less Invasive' Biventricular MCS

• UK-wide data: significant survival difference between ECMO-bridged and short-term VAD-bridged transplant patients - survival curves diverge early post-transplant, favouring VAD

• Longer ECMO support duration → worse outcomes (US and UK data consistent)

• Post-transplant survival from surgical BiVAD (CentriMag + Impella) bridging: good, matching or slightly exceeding standard UK 1-year survival

• Long-term durable LVAD bridging: less favourable - patients tend to be transplanted only when complications arise, making them higher-risk candidates at time of transplant

• Impella 5.5: LV Support via Axillary Artery:

  • Effective LV support device; QEB has extensive experience bridging patients from Impella 5.5 to durable LVAD without RHF - validates RV tolerance before commitment to durable device

  • Access: surgical cutdown to right axillary artery; 10mm Dacron graft sutured to artery; 18Fr motor (~6mm) requires axillary artery ≥6-7mm (may not be feasible in small women)

  • Impellea wire crosses aortic valve (pigtail or GR4 catheter guide); then exchanged for impella-specific 0.035" wire; impella advanced into LV; wire removed before starting

  • Licensed for 30 days; QEB have successfully supported patients >6 weeks

  • General anaesthesia required for axillary cutdown implant

  • TOE confirmation essential before leaving OR: impella tip 5cm below aortic valve, directed toward LV apex, away from mitral valve

  • Complications: device migration (dislodgement back to aorta - graft thrombus can prevent repositioning; may require full device replacement); hemolysis (less than Impella CP - lower RPM, larger bore); suction alarm (volume depletion or RHF); transient brachial plexus symptoms from axillary dissection; stroke risk

• Percutaneous RV Support Strategies:

  • Impella RP (femoral access): low flow, not currently in use; new Impella RP Flex (right IJV) not yet available

  • Protek Duo (29Fr dual-lumen, right IJV): drainage and PA return via single cannula; simpler but flow limited to ~3.5L/min at high settings - not favoured when high RV output needed

  • Two-cannula strategy (preferred at QE): 21-25Fr femoral venous drainage + 19Fr right IJV single-stage cannula advanced to pulmonary artery; achieves 4-5L/min flow; more flexible and easier to insert than Protek Duo

  • Alternative access: left axillary vein used successfully in patient with lymphoma-compressing SVC - drainage via left IJV supplemented axillary cannula, allowing full chemotherapy on support; patient went home fully recovered

  • PA cannula insertion technique: float balloon-flotation catheter (Swan-Ganz) to PA → cut catheter → wire with 0.025" → exchange to MPA1 catheter → feed stiff wire (Amplatz ExtraStiff) → advance PA cannula over wire

  • TOE and fluoroscopic guidance for PA cannula position; short-axis pulmonary artery view confirms flow

  • Neck headband: IJV cannula loops over patient's head, attached to headband - reduces traction and patient discomfort

• Less Invasive Biventricular MCS (Impella 5.5 + PA Cannula):

  • Combination of Impella 5.5 (LV support) and percutaneous PA cannula (RV support) provides biventricular assist without sternotomy

  • Potential advantages over surgical BiVAD: less surgical trauma, less blood transfusion (early data), no sternotomy take-down at transplant, potentially shorter recovery

  • Limitations: uncertain maximum support level at high cardiac output requirements; mobilisation more challenging (femoral venous cannula; IJV cannula causes neck discomfort); physiotherapy team less confident vs CentriMag patients

  • Post-switch from ECMO: central ECMO circuit left in for 24-48h as safety net, then oxygenator removed - patients transition to pure LVAD + percutaneous RVAD without remaining on ECMO

• MCS Selection Algorithm:

  • Likely recovery (acute MI, myocarditis): ECMO + Impella → attempt recovery; if longer support needed → consider less invasive BiV MCS

  • Bridge to transplant, established cardiomyopathy (unlikely recovery): CentriMag surgical BiVAD or Impella 5.5 (established long-duration feasibility)

  • Key principle: tailor device to patient — expected recovery potential, RV function, vessel size, support duration, and transplant access tier all factor in

NZ Context (Q&A Discussion)

• NZ lacks the donor pool of UK; BiVAD is not standard; if BiV support needed, NZ has used durable HeartMate 3 in RV position

• HM3 as RVAD: higher thrombosis risk; goal to transplant within 3 months–1 year before complications accumulate

• Alfred Hospital Melbourne: published series of ~20 BiVAD patients with good outcomes 

• Ex-plant at transplant is a significant operation

• Resource implications: BiVAD support requires ICU level care for prolonged periods