Ventricular Assist Devices in Children

Despite many improvements in the treatment of children with heart disease, heart failure that resists medical therapy remains a problem in the pediatric population. For the most severe forms of heart failure, heart transplantation has emerged as an effective therapy, affording longevity and a higher quality of life.

To keep children alive until a suitable donor organ becomes available, mechanical circulatory support is often needed. Historically, nonpulsatile devices such as extracorporeal membrane oxygenation (ECMO) and centrifugal pumps have been used. ECMO has the advantage of providing immediate cardiopulmonary support. However, with the shortage of donor hearts and the resulting waiting times, the use of these devices may be hazardous. Support with ECMO and centrifugal assist devices for prolonged periods of time is associated with significant risks, including bleeding, sepsis and neurologic complications. Also, the intricate circuits require the patient to be immobile, which has a negative impact on rehabilitation.

Similarly, if a child is treated with medicine alone before transplant, the results can be just as poor. If the child is too weak to eat well and does not have the energy to walk and move around, he or she cannot rehabilitate before transplant.

More appropriate circulatory support can be provided by a mechanical ventricular assist device (VAD), which acts as a bridge to heart transplantation, allowing for long-term support. These improve patients’ circulation and reverse end-organ dysfunction while permitting physical rehabilitation to improve the patient's overall condition and likelihood for successful transplantation.

VADS in Intermediate-Sized Children and Adolescents
Currently, intermediate-sized children and adolescents may be candidates for VADs used in adults, depending on their size and weight. At St. Louis Children’s Hospital (SLCH), Washington University pediatric cardiothoracic surgeons use a type of VAD that provides biventricular assistance – help for both the right and left ventricles (the lower chambers of the heart) – which many patients need.

Research has shown that pediatric patients placed on this type of VAD have a survival rate comparable to that in adult patients and that the survival rate is independent of age or body size.¹ In addition, the post-transplant survival rate for pediatric patients who use the VAD as a bridge to transplant is very high.^1,2

Older children who undergo heart transplantation are end-stage heart failure patients who suffer from either cardiomyopathy – a primary problem with the heart muscle – or congenital heart disease that cannot be corrected through additional surgery. Surgeons at SLCH report that pediatric heart transplant patients generally heal better than adults do because they don’t have as many medical problems associated with their heart disease.

VADs in Small Children
In the United States, there are currently no government-approved VADs for small children. However, the Berlin Heart EXCOR ® VAD recently became available for compassionate use in selected instances. The Berlin Heart has been developed for use in children, toddlers and even babies. This is possible through a variety of blood pumps (which range from 10 to 60 ml in volume) and a wide range of cannulae (tubes that connect to the heart chambers). The device can provide left ventricular, right ventricular or biventricular assistance.

The Berlin Heart EXCOR ® VAD (ranging from 10 to 60 ml in volume). Image courtesy of Berlin Heart Berlin Heart AG.

Although the Berlin Heart is attached to the heart, its two pumps are located outside of the body. It connects to a computer console, which can be wheeled around if the child is old enough to walk.

The Berlin Heart, which has been approved for use in Europe, was introduced in 1992 and has so far proved successful in children of all ages.³ At SLCH, during an initial 17-month period, surgeons implanted the Berlin Heart in seven children, ranging in size from 3 kg (6.6 pounds) to 35 kg (77 pounds). Although most of the children had cardiomyopathies, the device also was used in a child with complex congenital heart disease. All of the children received biventricular VADs, and six of seven went on to successful heart transplantation.

In order to receive approval to use the Berlin Heart, Washington University surgeons at SLCH must submit a number of protocols with the hospital’s review board and the U.S. Food and Drug Administration (FDA). Because the device now is being used more widely in the United States, acquiring the Berlin Heart takes longer than it did initially (approximately one week) because of production delays.

SLCH will be part of a clinical trial being planned for the Berlin Heart EXCOR ® VAD.

Sources:

1. Reinhartz O, Stiller B, Eilers R, Farrar D. Current clinical status of pulsatile pediatric circulatory support. ASAIO (American Society of Artificial Internal Organs) Journal. 2002;48(5):455-459.
2. Reinhartz O, Keith FM, Elbanayosy A, McBride LR, Robbins RC, Copeland JG, Farrar DJ. Multicenter experience with the thoracic ventricular assist device in children and adolescents. The Journal of Heart and Lung Transplantation. 2001;20(4);439-438.
3. Hetzer R, Stiller B. Technology insight: Use of ventricular assist devices in children. Nature Clinical Practice Cardiovascular Medicine. 2006;3:377-386.

For a consultation regarding a pediatric heart or lung condition, call:
(314) 454-6165

Pediatric Cardiothoracic Surgeons

• Pirooz Eghtesady, M.D., Ph.D.