Berlin Heart EXCOR: Implantation Strategy Overview

Principles, Implantation Strategy, and Clinical Outcomes

The Berlin Heart EXCOR is a paracorporeal, pulsatile ventricular assist device designed for infants and children with advanced heart failure who require durable mechanical circulatory support. In contemporary pediatric practice, it remains one of the most important options for patients who are too small for implantable continuous-flow devices, particularly when bridge-to-transplant support is needed [1-3]. Across published pediatric series, the device has consistently demonstrated that prolonged support is feasible in children of widely varying sizes, including very small infants, although complication burden remains substantial [2-5]. (PubMed)

From a surgical perspective, Berlin Heart implantation should not be regarded as simple cannula placement. Rather, it is the deliberate construction of a stable inflow-outflow circuit that must achieve three goals simultaneously: reliable ventricular decompression, effective systemic perfusion, and durable support with the lowest possible risk of thrombosis, suction events, bleeding, infection, and neurologic injury [2-4,6]. (PubMed)

1. Device Concept and Clinical Role

The EXCOR system consists of one or two extracorporeal blood pumps connected to the heart and great vessels through cannulae and driven by a pneumatic console. Depending on the underlying physiology, support may be configured as an LVAD, RVAD, or BiVAD. For isolated systemic ventricular failure, the most common pediatric configuration is left ventricular apical inflow with outflow to the ascending aorta. Pump size is selected according to patient size and required stroke volume, allowing use from infancy through adolescence [2,3]. (PubMed)

In most reported pediatric cohorts, Berlin Heart support has been used primarily as a bridge to transplantation, although bridge to recovery is also possible in selected patients [1-5,8]. Large multicenter and systematic review data show successful bridging to transplant or recovery in a majority of children, generally in the range of roughly two-thirds to three-quarters of patients, with variation according to body size, diagnosis, and need for biventricular support [2-5,8]. (PubMed)

2. Indications and Patient Selection

Typical candidates include children with severe left ventricular failure, biventricular failure, or progressive end-stage heart failure refractory to maximal medical therapy. In practice, the device is often considered when recovery on temporary support is unlikely and when extracorporeal membrane oxygenation is no longer an appropriate long-term strategy. Earlier implantation, before severe end-organ injury develops, appears advantageous, because worse hepatic and renal dysfunction, smaller patient size, and the need for BiVAD support have all been associated with poorer outcomes [2,3,8]. (PubMed)

Infants deserve particular attention. Historically, small body size was associated with higher procedural complexity and complication risk, but more recent infant-specific series have shown that excellent bridging outcomes can still be achieved in the first year of life when implantation timing and postoperative management are optimized [5]. (PubMed)

3. Cardiopulmonary Bypass Strategy

Cardiopulmonary bypass strategy must be individualized according to intracardiac anatomy, the need for associated repair, and the planned inflow and outflow sites. Mild hypothermia is generally acceptable. A single right atrial venous cannula may be sufficient when the right atrium is not being opened; however, bicaval cannulation is preferable when intracardiac procedures such as atrial septal defect closure or tricuspid valve repair are required.

The need for an aortic cross-clamp depends on the operative circumstances. If native cardiac ejection is minimal and left-sided venting is effective, LV coring may sometimes be performed without cross-clamping. In contrast, when there is significant ejection, concern for air embolism, or limited exposure, cross-clamping provides a safer and more controlled field. Similarly, in small children with a short ascending aorta, side-clamping may be impractical, making formal aortic cross-clamping and controlled graft implantation more secure. Although detailed technical descriptions are underrepresented in the outcome literature, these operative principles are essential for safe implantation and for avoiding preventable inflow or outflow malposition. The broader literature confirms that complications accumulate with longer support and in smaller children, underscoring the importance of meticulous initial surgery [3,4,7]. (PubMed)

4. Outflow Cannulation

For LVAD support, outflow is typically established to the ascending aorta, either by direct cannulation or, more commonly, by anastomosing a vascular graft end-to-side to the ascending aorta and then connecting the outflow cannula to that graft. The graft route usually provides better control of geometry and reduces crowding at the aortic wall.

Several technical principles are critical:

• The graft should be oriented to create smooth forward flow into the ascending aorta.
• Kinking, torsion, or an excessively acute angle should be avoided.
• The relationship of the graft to the right coronary artery must be assessed carefully.
• In small patients, limited aortic length may dictate clamp strategy and graft position.

Outflow reconstruction is not merely a matter of connection; it directly affects resistance, turbulence, and effective systemic output. Significant aortic insufficiency must also be recognized, because severe regurgitation can create a recirculating loop that reduces net forward flow and limits ventricular decompression.

5. Inflow Cannulation and LV Apical Coring

The left ventricular apex is the standard and most physiologic inflow site for LVAD support. Proper apical inflow permits effective decompression of the systemic ventricle, stable drainage, and more favorable alignment with the long axis of the LV cavity.

Pre-coring planning should identify:

• the coronary arteries on the epicardial surface,
• the muscular apical dimple,
• the expected axis of the LV cavity,
• the relationship to the ventricular septum, papillary muscles, and mitral valve apparatus.

Echocardiographic guidance before coring may be helpful, especially in small hearts or distorted ventricular geometry. After ventriculotomy and coring, obstructing trabeculations or muscle bundles should be resected as needed, and the inflow cannula should be directed toward the body of the LV cavity rather than toward the septum or subvalvar mitral structures. Pledgeted sutures are then used to reinforce the apical sewing site and secure the cannula in a stable, hemostatic orientation.

This step is central to long-term function. A poorly oriented inflow cannula may technically appear satisfactory at implantation yet later produce intermittent obstruction, suction events, inadequate decompression, or thrombus formation. Because published studies remain heavily weighted toward outcomes rather than operative detail, these anatomical and geometric principles deserve explicit emphasis in textbook-style discussion.

6. Intraoperative Verification Before Final Connection

Before final connection and initiation of support, the LV cavity should be inspected directly for thrombus, debris, residual obstructing muscle, or unfavorable cannula direction. Final confirmation should include:

1. satisfactory inflow orientation within the LV cavity,
2. unobstructed outflow graft geometry,
3. adequate de-airing, and
4. absence of major residual lesions that would compromise support.

In pediatric VAD surgery, errors of millimeters can become major clinical problems. For that reason, the quality of implantation is determined not only by the pump chosen, but by the precision of intraventricular alignment and outflow reconstruction.

7. Early Post-implant Hemodynamic Goals

Immediately after support is started, the operative and ICU teams should confirm that the device is producing the intended physiology:

• effective LV decompression,
• reduction in filling pressure,
• stable systemic perfusion,
• appropriate septal position,
• absence of repetitive suction events,
• preserved right-sided filling and output.

Right ventricular performance remains especially important. Inadequate RV output may limit pulmonary blood flow and LV preload, thereby reducing effective LVAD filling. In some patients, an initial LVAD strategy must therefore be revised to BiVAD support [2,3]. (PubMed)

8. Outcomes and Major Complications

The major strength of the current literature is outcomes reporting. Early North American experience demonstrated that pediatric Berlin Heart support could successfully bridge a substantial proportion of children to transplantation or recovery, thereby establishing the platform in clinical practice [1]. The larger U.S. multicenter experience later showed 12-month survival of 75%, including 64% transplanted, 6% recovered, and 5% alive on device support [2]. The long Berlin experience and subsequent systematic review confirmed that acceptable bridging outcomes can be achieved across a broad age range, while also emphasizing that lower body weight and more complex support strategies remain important risk factors [3,4]. (PubMed)

Neurologic injury remains one of the most serious limitations of Berlin Heart support. In the pediatric investigational device exemption trial, 29% of children experienced at least one neurologic event, predominantly ischemic stroke, and neurologic dysfunction was strongly associated with mortality [6]. Thrombotic complications and pump exchanges have also been major issues across series, reflecting the persistent challenge of hemocompatibility in paracorporeal pulsatile support [3,4,6,7]. (PubMed)

At the same time, infant outcomes may be better than historically assumed when management is highly structured. In one focused infant series, survival to transplantation or recovery reached 86%, with relatively low neurological dysfunction [5]. More recent retrospective data continue to support the effectiveness of the Berlin Heart as a bridge strategy in pediatric end-stage heart failure, although long-term morbidity and complication surveillance remain essential [8]. (PubMed)

9. Contemporary Perspective

Despite the emergence of newer pediatric support technologies, the Berlin Heart EXCOR remains the dominant durable option for many infants and small children. Recent reports on newer mobile driver systems suggest improved portability and quality of life during support, but they do not change the core surgical principles of implantation: correct inflow geometry, secure outflow reconstruction, reliable decompression, and disciplined postoperative anticoagulation and surveillance [9]. (PubMed)

Conclusion

Berlin Heart EXCOR implantation in children is a technically demanding operation that lies at the intersection of anatomy, hemodynamics, and long-term device biology. The literature strongly supports its role as an effective bridge to transplantation in pediatric end-stage heart failure [1-5,8]. However, the same literature also shows that neurologic and thrombotic complications remain major determinants of outcome [3,4,6,7]. For that reason, successful Berlin Heart support begins not after implantation, but during implantation itself—with precise selection of the LV apical inflow site, careful construction of ascending aortic outflow, appropriate CPB strategy, and rigorous intraoperative confirmation of cannula position and decompression.

References

[1] Rockett SR, Bryant JC, Morrow WR, Frazier EA, Fiser WP, McKamie WA, Johnson CE, Chipman CW, Imamura M, Jaquiss RDB. Preliminary single center North American experience with the Berlin Heart pediatric EXCOR device. ASAIO J. 2008;54(5):479-482.

[2] Almond CS, Morales DL, Blackstone EH, Turrentine MW, Imamura M, Massicotte MP, Jordan LC, Devaney EJ, Ravishankar C, Kanter KR, Holman W, Kroslowitz R, Tjossem C, Thuita L, Cohen GA, Buchholz H, St Louis JD, Nguyen K, Niebler RA, Walters HL 3rd, Reemtsen B, Wearden PD, Reinhartz O, Guleserian KJ, Mitchell MB, Bleiweis MS, Canter CE, Humpl T. Berlin Heart EXCOR pediatric ventricular assist device for bridge to heart transplantation in US children. Circulation. 2013;127(16):1702-1711.

[3] 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.

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

[5] Davis LM, Lee MGY, Sheridan B, d'Udekem Y, Brizard C, Konstantinov IE, Mathew J, Brink J. Berlin Heart EXCOR support in the first year of life: a single centre experience. Heart Lung Circ. 2021;30(3):446-453.

[6] Jordan LC, Ichord RN, Reinhartz O, Humpl T, Pruthi S, Tjossem C, Thuita L, Massicotte MP, Li JS, Fraser CD Jr, Devaney EJ, Almond CS, Rosenthal DN. Neurological complications and outcomes in the Berlin Heart EXCOR pediatric investigational device exemption trial. J Am Heart Assoc. 2015;4(1):e001429.

[7] Komori M, Hoashi T, Sakaguchi H, Imai K, Okuda N, Fukushima N, Kurosaki K, Ichikawa H. Short-term outcomes of EXCOR Paediatric implantation. Interact Cardiovasc Thorac Surg. 2022;35(1):ivac051.

[8] Dawary M, Brotons D, Tsai FW. Berlin Heart EXCOR as a bridge to transplantation in pediatric end-stage heart failure: a retrospective cohort study. J Cardiovasc Dev Dis. 2025;12(12):465.

[9] Conway J, Pidborochynski T, Ly D, Mowat L, Freed DH, De Villiers Jonker I, Al-Aklabi M, Holinski P, Anand V, Buchholz H. First North American experience with the Berlin Heart EXCOR Active driver. J Heart Lung Transplant. 2024;43(11):1861-1863.