Cold Oxygen Flush Revives Donor Hearts for Children Awaiting Transplants

Surgeons at Monroe Carell Jr. Children’s Hospital at Vanderbilt have reported a milestone that could reshape the landscape of pediatric heart transplantation. In a study published in the New England Journal of Medicine, the pediatric cardiac surgery team, working alongside Vanderbilt Health’s adult heart transplant program, described the successful recovery and transplantation of five donor hearts in children using a novel organ preservation technique known as REUP, short for rapid recovery with extended ultraoxygenated preservation. Since the study period ended, five additional children have received donor hearts recovered with the same method, bringing the total to ten young recipients whose lives were saved by hearts that, under conventional protocols, might never have reached the operating table.

The significance of the achievement lies in the category of donors involved. REUP was originally developed by Vanderbilt’s adult heart transplant team for hearts donated after circulatory death, a category abbreviated as DCD. In DCD donation, the donor’s heart has already stopped beating before recovery begins, which distinguishes these organs from those retrieved after brain death, when the heart is still pumping at the time of procurement. Historically, recovering a heart that has ceased beating posed a fundamental problem: cardiac tissue deprived of blood flow begins to deteriorate rapidly, and the organ must somehow be revived or preserved before it can be transplanted into a recipient.

Existing approaches to DCD heart recovery have relied on reanimation. In one strategy, the donor’s circulation is restored in the body so the heart resumes beating before it is removed. In another, the heart is placed on a specialized ex situ perfusion machine that pumps blood or perfusate through it to restart its function outside the body. Both strategies can work, but each carries drawbacks. Reanimation inside the donor’s body raises ethical concerns in some settings, because it involves restoring circulation after death has been declared. Perfusion devices, meanwhile, can be expensive, technically complex, and constrained by the size of the patient, a limitation that is particularly consequential in pediatrics, where donor hearts may be as small as a walnut.

REUP takes a fundamentally different path. Rather than reanimating the donor heart, the technique preserves it by flushing the organ with a cold, oxygen-rich solution after death has occurred. The ultraoxygenated perfusate delivers oxygen to the myocardial tissue while the low temperature slows metabolism, allowing the heart to be maintained in a viable, non-beating state until transplantation. Because the heart is never restarted, the method sidesteps the ethical objections associated with in situ reanimation, and because it does not depend on bulky perfusion machinery sized to the patient, it can in principle be applied across the full range of donor sizes, from the smallest neonates to adolescents.

The pediatric adaptation of the technique is the heart of the new report. In the NEJM article, the team described five donor hearts recovered with REUP and transplanted into children ranging in age from just two days to fourteen years old. That span is itself notable: neonatal and infant hearts are among the most difficult organs to recover and transplant, and the demonstration that the technique works across all pediatric age groups suggests it could be applied broadly rather than being confined to a narrow subset of donors.

The outcomes reported in the study were striking. The five recipients waited an average of only twenty days for transplantation, a figure that stands in sharp contrast to the many months children often spend on the waiting list. No donor hearts were discarded during the recovery process, and every recipient demonstrated strong heart function after surgery. None of the children required mechanical circulatory support following transplantation, none experienced primary graft dysfunction, a feared early complication in which the transplanted heart fails to perform adequately, and none showed evidence of rejection during the study period. For a first-in-children application of a new preservation method, that combination of results represents an unusually clean safety and efficacy profile.

The clinical context helps explain why the Vanderbilt team describes the technique as transformative. More than 2,000 children are on the heart transplant waitlist in any given year, and waiting times can stretch across many months, particularly for neonates and infants, whose donor pool is the smallest and whose clinical deterioration while waiting is often the fastest. Long waits carry a grim toll: waitlist mortality among children awaiting heart transplantation is estimated at roughly twenty percent. In other words, one in five children on the list may die before a suitable organ becomes available. Any technique that reliably converts currently unusable donor hearts into transplantable ones attacks that mortality directly, and the Vanderbilt investigators noted that without REUP, the hearts in their study would not have been available for transplantation at all.

The ethical dimension of the work deserves particular emphasis. All of the donor recoveries included in the pediatric study took place in settings where donor heart reanimation was not permitted because of ethical concerns. This means the study population was drawn from precisely the circumstances in which DCD hearts are most often lost to transplantation: institutions and jurisdictions where the prevailing rules forbid restarting circulation in a donor after death. By demonstrating that hearts can be recovered and preserved without any reanimation step, REUP opens a pathway for those organs to be used in places where existing methods are simply off the table, potentially expanding the donor pool not only by making more hearts usable but by making them usable in more places.

The pediatric program’s success builds on a foundation of prior adult experience at Vanderbilt Health. Earlier studies from the adult heart transplant team showed that donor hearts could be safely recovered and preserved without reanimation before transplantation, findings that suggested the approach could make substantially more donor hearts available to patients in need. Aaron Williams, MD, Assistant Professor of Cardiac Surgery at Vanderbilt Health and first author of the NEJM article, noted that REUP has already helped expand the donor pool for adult heart transplantation, allowing the team to transplant more patients, recover hearts from greater distances, and achieve excellent outcomes. The ability to recover hearts across greater geographic distances is a quiet but important benefit of a preservation method that does not require the donor heart to be beating: organs can tolerate longer transport intervals when they are held in a cold, oxygenated, metabolically suppressed state.

Ziv Beckerman, MD, Associate Chief of Pediatric Cardiac Surgery and Surgical Director of Pediatric Heart Transplantation in the Golisano Pediatric Heart Institute at Monroe Carell and senior author of the article, described the approach as truly transformative for the field of pediatric heart transplantation, emphasizing that the ability to expand the organ donor pool and utilize hearts that would otherwise be discarded represents a genuine advance for patients. The team has stated its intention to help other transplant programs advance and adopt the technique, a dissemination effort that could determine how quickly the benefits reach the broader population of waiting children. If the early results hold up as the method spreads, a preservation strategy built on a simple idea, keeping a stopped heart cold and oxygenated rather than forcing it to beat, may become a standard tool in the effort to shorten wait times and save more young lives.

Subject of Research: Rapid recovery with extended ultraoxygenated preservation (REUP) of donor hearts donated after circulatory death for pediatric heart transplantation

Article Title: Monroe Carell Jr. Children’s Hospital at Vanderbilt leads breakthrough heart recovery method for pediatric transplants

Article References: Monroe Carell Jr. Children’s Hospital at Vanderbilt leads breakthrough heart recovery method for pediatric transplants. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: pediatric heart transplantation, REUP, donation after circulatory death, organ preservation, Vanderbilt, Monroe Carell Children's Hospital, New England Journal of Medicine, donor pool expansion, waitlist mortality, cardiac surgery, neonatal transplant, organ recovery