‘Machine perfusion is the future for more and better donor hearts and lungs’

How can you ensure more available donor hearts and lungs of good quality? Thoracic surgery resident at the UMCG Vincent van Suylen investigated this. ‘By joining forces and improving the perfusion strategy together’.

During his graduation research, resident Vincent van Suylen already discovered that, contrary to expectations, lungs from donors who died after circulatory death (DCD) work just as well in the long term as lungs from donors who died after brain death (DBD). That was obviously good news.

During his doctoral research, Van Suylen delved further into heart and lung transplants. For example, he investigated a technique to improve the quality of donor lungs. 'Normally, you store lungs on ice after removal until the transplant. If you have doubts about their quality, you can also connect them to a perfusion machine. They are then flushed with fluid and ventilated: ex vivo lung perfusion (EVLP). This allows you to ‘test’ the lungs to predict how they will function after the transplant. At the same time, you can also improve them, for example by removing excess fluid. In my research, I compared the outcomes of conventional lung transplants and transplants after EVLP. They turned out to be comparable. That means that the lungs that were only approved after EVLP perform just as well as lungs that were not in doubt from the start.'

More and better donor hearts

Van Suylen also looked at heart transplants. 'Since March 2021, we have been performing heart transplants in the Netherlands not only after DBD donation but also after DCD donation. In theory, this could make up to 40 extra donor hearts available per year.' In DCD heart donation, the heart is connected to a perfusion machine immediately after removal and flushed with oxygen-rich blood: ex situ heart perfusion (ESHP). 'This keeps the heart in good condition and, just like with the lungs, you can test it before the transplant.' That flushing is done as standard at body temperature (37°C). 'Together with my colleagues, I developed a perfusion method at 21°C. That has advantages: the heart does not beat, uses less energy, and is less damaged by inflammatory reactions. Before the transplant, we still test the heart at body temperature. For this, we developed a new evaluation machine. Just like with the current machine, we look at whether the heart is beating well and measure a substance that indicates whether there is damage. What is new is that we also measure how powerfully the heart squeezes. Together with UMC Utrecht and Erasmus MC, we already tested our techniques in donor hearts that had been rejected for transplant. In the future, we hope to further improve the quality of DCD and DBD donor hearts with these techniques.'

New group of donors

The final part of Van Suylen's research focused on heart transplantation after euthanasia. For lungs, livers, kidneys, and pancreases, this has been happening for longer. For hearts, it is new. With his perfusion and evaluation machine, Van Suylen tested two hearts that were removed after euthanasia. 'These euthanasia patients wanted to donate their organs after their death, but their heart was not suitable for transplant. They were pleased that it could be used for research. The initial results are promising: the hearts seem to function well. People who choose euthanasia form a new, valuable group of potential heart donors.'

Future

Van Suylen sees many possibilities for the future. 'If we join forces and work together on an optimal perfusion strategy, there is still much to be gained. Certainly in the field of DCD heart transplantation – there are only a few centers in the world that do this. In addition, heart donation after euthanasia also offers possibilities. It will take years before we have investigated everything precisely, but ultimately we hope to have more organs of better quality available.'