April 29, 2023
Mayo Clinic Children's Center heart transplant specialists have completed their first pediatric transplant with the "heart-in-a-box" perfusion system, noted for sustaining donor hearts while awaiting transplant.
"So, instead of the heart being cold and carried in solution during a transport, it was supported by an ex vivo system that kept the heart beating throughout the trip," says Jonathan N. Johnson, M.D., pediatric cardiology chair at Mayo Clinic Children's Center in Minnesota. "The system allowed us to use a heart from farther away than we otherwise would have. With this system, a donor heart can now travel up to six hours or 1,000 miles. It also allows us to use older hearts and hearts that previously would have been unusable because transplant specialists would consider them expanded-criteria donations."
This development is part of a larger Mayo Clinic-wide technology innovation effort to serve the needs of and offer significant benefits to patients requiring heart transplant. Though transplant specialists abroad have used this technology, few U.S. pediatric centers have used it for a pediatric heart transplant, says Dr. Johnson.
Benefits of heart-in-a-box system for pediatric transplant
Standard heart transplant procedures typically preserve a donor heart for 3 to 5 hours. Yet, the new heart-in-a-box system allows preservation for several additional hours, maintaining the heart in a beating status. In the case of the newly transplanted pediatric patient, the transport time was five hours and nine minutes, with an additional 30 minutes for placing the organ in the machine and then removing it. The ischemic time on the heart was just over an hour. Beyond extending preservation time, the heart-in-a-box system potentially will widen the donor pool. The technology allows the novel use of donation after circulatory death (DCD) hearts — the organs of patients who have experienced severe damage incompatible with life — through revival and support of nonbeating hearts.
When transplant specialists insert a donor heart in this machine, it perfuses the organ with warm, oxygenated blood. This process transitions the heart from nonbeating to beating status. It also measures the heart's function through analysis of the heart's hemodynamic parameters. The machine monitors the organ every 15 to 30 minutes, much as medical professionals monitor a patient in an ICU. The transplant team must resuscitate the heart until it meets strict transplant criteria. The heart-in-the-box technology allows transplant professionals certainty the organ meets these standards before final transplant acceptance.
This technology also offers better outcomes and fewer patient deaths while awaiting a heart, according to the Mayo Clinic transplant specialists.
Some medical centers hesitate to use expanded-criteria hearts and have concerns about ischemia time, say Mayo Clinic transplant specialists. However, Mayo Clinic professionals are enthusiastically pursuing the potential to make more donor hearts available via perfusion of expanded-criteria hearts, especially DCD organs.
Costs amidst benefits for use of heart-in-the-box technology
Using a heart perfusion system for transplant does present some costs, financial and otherwise. Use of the heart-in-a-box system requires considerable surgical skill and significant logistical support. The system also increases heart transplant costs, due to additional personnel required. Yet Mayo Clinic transplant specialists indicate that even if the system's use impacts a medical center's bottom line, it adds significant value. The perfusion system is critical to shorten patients' transplant wait times and reduce pretransplant hospital length of stay, thus decreasing costs.
Future for heart perfusion systems
Mayo Clinic Children's Center pediatric heart transplant specialists say they will not use the perfusion system in all heart transplants. The reason for this is that it is unnecessary for younger donors or in local surgery where organ transfer occurs more rapidly. However, they are excited about the potential to decrease wait times and increase donor utilization for recipients.
The FDA approved the heart-in-a-box system for DCD hearts in the fall of 2021. The Mayo Clinic Transplant Center performs more than 140 heart transplants yearly across its three campuses.
Although heart perfusion does not restore organs per se presently, that is the long-range goal, according to Mayo Clinic heart transplant specialists. They indicate heart perfusion provides pseudo-restoration, yet only with traditionally transplant-eligible hearts currently.
For more information
Organ Care System (OCS) Heart System — P180051. U.S. Food and Drug Administration.
Refer a patient to Mayo Clinic.