Plain language summaries of research

This is a plain language summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

Finding suitable hearts for children

There are currently more children with serious heart problems needing a heart transplant than ever before. However, the number of heart transplants happening each year has been going down, and many children are not able to receive a transplant in time.

The main challenge is finding hearts of the right size from donors, especially for babies and very young children. Even though there are children in the UK and Europe who donate their organs, many of these donated hearts cannot be used.

One reason for this is that the technology used to preserve adult donor hearts while waiting for transplantation is too large for very small children. The machines require the donor to weigh at least 50 kilograms, which rules out very small children.

The machines are needed to transport hearts long distances - the current storage techniques only allow 4-6 hours between removing the heart from the donor and starting the blood supply again in the recipient. They are also needed for donors who are declared dead after their heart stops beating (donation after circulatory death) as their hearts suffer some damage, which the machines can reverse.

 

HOPE: the new technology

HOPE stands for hypothermic oxygenated perfusion. This is a special way of keeping a donated heart in good condition between the time it is removed from the donor and the time it is transplanted into the new recipient.

It works by connecting the heart to a machine that pumps cold blood with oxygen and other nutrients through the heart. This process helps the heart to stay healthy and repair any damage it may have while it waits to be transplanted.

The technology has already been working well with adult hearts, but researchers wanted to find out if this method could be adapted to work with hearts from young children, babies, and even newborns.

 

How did researchers test this method?

Before testing the equipment with human hearts, researchers tried it on hearts from pigs that were a similar size to hearts from human newborns and infants. Because the blood vessels in these hearts are so small, the researchers needed to develop special surgical techniques to connect the heart to the HOPE machine. One of these techniques is called arch augmentation, which widens the donor's blood vessel (aorta) to allow a tube which supplies blood to the heart to fit comfortably.

The tests using pig hearts showed that hearts from donors as little as 3 kilograms could be successfully preserved using HOPE. The hearts continued to have good blood flow and showed no signs of damage after several hours of preservation.

 

What happened when children were transplanted using the new method?

As part of this study, 6 children between the ages of 22 months and 13 years received heart transplants using the HOPE machine. The donated hearts came from children aged between 16 months and 13 years.

Three of the donated hearts came from children whose hearts had stopped beating (called donation after circulatory death) and three came from children who were declared dead after tests that established brain death (called donation after brainstem death).

All six transplants were successful, and the hearts were preserved using the HOPE machine for about 4.5 hours on average. These transplants were the first in the world using this technique in small donors.

 

Why is this research important?

This research offers a solution to help more children receive life-saving heart transplants. Without the HOPE machine, many small hearts cannot be used, meaning that children have to wait longer for a transplant and may not receive one in time.

It showed that the method can be used safely with hearts from donors as small as 9 kilograms. The researchers believe that, based on their research so far, the method could eventually work with hearts from newborn babies. 

This new method is beneficial because:

• It gives surgeons more time to perform complex operations because the donated heart stays in good condition for longer
• It means that the donated hearts can be transported over greater distances, which increases the chances of finding a good match between the donor and recipient
• It allows small hearts from donors who have been declared dead after their heart stops beating (donation after circulatory death) to become possible

None of the children who received hearts with this method needed extra support machines after their transplant, which shows that the hearts were in good condition when transplanted.

 

What happens next?

The researchers acknowledge that this study only involved 6 children, and more research with more patients would be needed to confirm these encouraging results. The team has already expanded their acceptance of donor hearts to include hearts from newborns.

They have shared their methods and experiences in the hope that other transplant centres around the world will adopt this approach to help more children receive the heart transplants they need.

Read the full article 

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Funding

This study was funded by red Sky Foundation, CHUF, and Newcastle Hospitals Charity.

 

The original article

This is a summary of: Chilvers, N., Vandendriessche, K., Moeslund, N. et al. HOPE for children: successful pediatric DCD heart transplantation using hypothermic oxygenated perfusion. The Journal of Heart and Lung Transplantation (2025). Available at: https://www.jhltonline.org/article/S1053-2498(25)02308-3/fulltext 

This summary has been approved by a member of the research team.