Berlin Heart EXCOR #2: Implantation—CPB Strategy

Berlin Heart EXCOR implantation is frequently performed in critically ill infants and children with minimal physiologic reserve. The CPB strategy should therefore be rapid to establish, mechanically stable, and easily escalated, while explicitly controlling three recurrent hazards: ventricular distension, systemic air entrainment, and end-organ ischemia.

1) Core objectives of CPB for EXCOR implantation

1. Secure systemic perfusion early (hemodynamic “rescue”).
2. Decompress the failing ventricle (reduce wall stress and subendocardial ischemia).
3. Create a controlled operative field for:
• inflow site preparation (atrium vs LV apex),
• coring + cannula seating
• outflow graft/cannula implantation.
4. Prevent systemic air embolism, particularly if any native ejection persists.

2) Temperature strategy

• Mild hypothermia (~34°C) is commonly used for EXCOR implantation as a pragmatic balance between metabolic reduction and workflow efficiency.
• Practical rationale:
• modest reduction in metabolic demand without the complexity of deeper hypothermia,
• simplified rewarming and less exacerbation of bleeding/coagulopathy.

3) Venous drainage strategy: Single RA vs bicaval

3.1 Default: Single right atrial (RA) venous cannula

• Usually sufficient when the RA is not opened (typical “closed-RA” implant).
• Advantages:
• faster set-up,
• less dissection in unstable/small patients,
• adequate drainage for most cannula/graft work.

3.2 Choose bicaval cannulation (SVC/IVC) when the RA must be opened

• Typical indications:
• ASD closure
• tricuspid valve repair
• any planned right-sided intracardiac work requiring a bloodless RA field.
• Beating-heart atrial inflow strategies may also require RA exposure with bicaval control/snares, depending on the approach and target site [1].

Operational pearl

• If bicaval cannulation is anticipated, decide early; late conversion can add time, bleeding, and hemodynamic instability.

4) Arterial cannulation: keep it conventional, keep it reliable

• Standard aortic cannulation is typical; modify according to anatomy, prior palliation, and available space for outflow reconstruction.
• In small patients or when ascending aortic “real estate” is limited, technical modifications have been described to improve cannula/outflow positioning and hemostasis (e.g., conduit-based solutions and cannula extensions) [2].
• Practical goals:
• avoid crowding the ascending aorta (especially when an outflow graft to the aorta is planned),
• minimize kinking/tension at the outflow anastomosis.

5) Aortic cross-clamp: arrest vs beating is a task- and physiology-driven choice

The cross-clamp decision should be framed as a risk trade-off: myocardial ischemic exposure and workflow complexity versus the benefits of a still, controlled heart and simplified air management.

5.1 When beating-heart implantation is reasonable

• When implantation steps can be completed without intracardiac reconstruction.
• Particularly attractive when:
• minimizing ischemic time is prioritized,
• the cross-clamp adds complexity without clear benefit.
• Beating-heart CPB with atrial access has been described for selected patients, including an atrial septal inflow strategy in the setting of severe diastolic dysfunction and a small LV [1].

5.2 When cross-clamp/cardiac arrest may be selected

• If intracardiac repair is required (e.g., septal defect closure, valve work).
• If exposure is constrained and manipulation risks uncontrolled air entry or inadequate visualization.
• Conceptual rule: cross-clamp is not “routine” for EXCOR implantation; it is task-dependent.

6) LA/LV venting: central to myocardial protection and field control

LA/LV venting should be treated as a core element rather than an optional adjunct.

Why it matters

• Prevents LV distension (especially with aortic insufficiency, bronchial return, residual pulmonary venous return).
• Reduces wall stress and supports subendocardial perfusion.
• Stabilizes the field for:
• coring and cannula seating,
• de-airing maneuvers when needed.

7) Inflow strategy: Atrium vs ventricle (why it changes the CPB plan)

Inflow site selection is not purely technical; it is a physiology-matching decision that directly determines the exposure, air risk, and decompression strategy.

7.1 Atrial inflow (LA/RA depending on configuration)

• Consider when:
• LV cavity is small or geometry is hostile to apical cannulation,
• severe diastolic dysfunction makes apical coring less favorable,
• an alternative inflow route is required to achieve stable unloading.
• A novel atrial septum inflow cannulation technique has been reported as a strategy for small LVs with severe diastolic ventricular failure, performed on a warm, beating heart with bicaval control and right atriotomy [1].
• Important trade-off: atrial inflow may increase thrombotic risk in some configurations, so selection should be explicit and individualized [1].

7.2 Ventricular inflow (LV apical cannulation with coring)

• Standard for LV support when the apex is suitable.
• The coring step is the highest-risk convergence point for:
• exposure,
• decompression,
• air control.

8) “No cardiac ejection” scenario: why coring may be feasible without AXC (and the boundary conditions)

If there is truly no effective native ejection, unclamped coring with aggressive LA/LV venting may be feasible because systemic air propulsion is limited. However, this strategy is conditional:

• ✅ Reasonable only when no effective ejection exists and is unlikely to return during manipulation.
• ⚠️ If even intermittent ejection persists or can reappear, air risk becomes clinically relevant, and the air-control plan must escalate (including consideration of AXC, meticulous de-airing, and tighter field discipline).

This conservative posture is justified by the high burden of neurologic events in EXCOR populations, where ischemic stroke is common and neurologic injury is a leading cause of death [3,4]. Additional single-center analyses also identify neurologic complications and risk factors during pulsatile VAD support in children [5].

9) Neurologic risk as the “forcing function” for CPB strategy

Even when the literature is sparse on granular CPB technique comparisons, the outcome signal is unambiguous: neurologic events are frequent and consequential.

• In a large prospective cohort experience, approximately 29% of children experienced at least one neurologic event, with many events being ischemic strokes and often occurring early during support [4].
• In broader US experience with EXCOR, outcomes analyses also highlight stroke and neurologic injury as major adverse events in this population [3].
• Systematic reviews summarize persistently high complication burdens across series, reinforcing the need for meticulous peri-implant strategy and surveillance [7].

Implication for the operative plan

• Treat air-management and LV decompression as first-class objectives, not secondary “nice-to-haves.”

10) A clean CPB decision pathway (slide-/chapter-ready)

1. Initiate CPB early → stabilize systemic perfusion.
2. Temperature: mild hypothermia around 34°C (institutional standard).
3. Venous cannulation
• single RA cannula if RA remains closed,
• bicaval if RA will be opened (ASD/TV repair or atrial inflow strategy) [1].
4. Venting: LA/LV vent to prevent distension and support controlled coring/field management.
5. Clamp decision
• beating-heart default for isolated cannulation/graft work,
• clamp/arrest when intracardiac tasks or air-risk physiology demands tighter control.
6. Inflow selection
• LV apex (coring) vs atrial/atrial septal inflow based on anatomy/physiology and thrombosis considerations [1].
7. Air strategy
• “no-ejection” physiology may allow unclamped coring in selected cases,
• if ejection exists/returns: escalate air-control measures and consider AXC, recognizing the neurologic event burden [3,4].

References

[1] Ma M, Yarlagadda VV, Rosenthal DN, Maeda K. A novel inflow cannulation strategy for pediatric mechanical circulatory support in small left ventricles. J Thorac Cardiovasc Surg. 2017;154(1):115-117.e1.

[2] Botha P, Hasan A, Perri G, Filippelli S, Griselli M. Modified technique for the implantation of Berlin Heart EXCOR ventricular assist device in children. World J Pediatr Congenit Heart Surg. 2012;3(3):373-377.

[3] Almond CS, Morales DLS, Blackstone EH, et al. Berlin Heart EXCOR Pediatric Ventricular Assist Device for Bridge to Heart Transplantation in US Children. Circulation. 2013;127(16):1702-1711.

[4] Jordan LC, Ichord RN, Reinhartz O, et al. Neurological complications and outcomes in the Berlin Heart EXCOR® pediatric investigational device exemption trial. J Am Heart Assoc. 2015;4(1):e001429.

[5] Polito A, Netto R, Soldati M, et al. Neurological complications during pulsatile ventricular assistance with the Berlin Heart EXCOR in children: incidence and risk factors. Artif Organs. 2013;37(10):851-856.

[6] Hetzer R, Kaufmann F, Delmo Walter EM. Paediatric mechanical circulatory support with Berlin Heart EXCOR®: development and outcome of a 23-year experience. Eur J Cardiothorac Surg. 2016;50(2):203-210.

[7] Rohde S, Antonides CFJ, Dalinghaus M, et al. Clinical outcomes of paediatric patients supported by the Berlin Heart EXCOR: a systematic review. Eur J Cardiothorac Surg. 2019;56(5):830-839.

[8] Morales DLS, Zafar F, Almond CS, et al. Berlin Heart EXCOR use in patients with congenital heart disease. J Heart Lung Transplant. 2017;36(11):1209-1216.

[9] Weinstein S, Bello R, Pizarro C, et al. The use of the Berlin Heart EXCOR in patients with functional single ventricle. J Thorac Cardiovasc Surg. 2014;147(2):697-705.