Preserving Heart Function in Donors Declared Dead According to Hemodynamic Criteria Could Improve Access to Heart Transplant – ScienceDaily

New research has concluded that more donated hearts may be suitable for transplantation if they continue to function inside the body for a short time after the death of the donor.

Organ functioning is preserved by reactivating local circulation to the heart, lungs, and abdominal organs—but, crucially, not to the brain—for patients whose hearts have stopped beating for five minutes or more and are declared dead according to circulatory criteria (donation after circulatory death, or DCD).

It is hoped that this technology will increase the number of usable donated hearts by up to 30% in the future, helping to address the shortage of transplant organs. In 2021, 8,409 heart transplants were reported to the Global Observatory on Donation and Transplantation (GODT) by 54 countries. This activity contrasts with the 21,935 patients on the heart waiting list during 2021, of whom 1,511 were on hold and many became too ill to receive a transplant.

John Luca, a final year medical student at Gonville & Caius College, University of Cambridge, and first author of the study, said: “Heart transplants are the last bastion for patients with end-stage heart failure. And they are successful — patients who receive the transplant live on average. Another 13 to 16. And the biggest problem they have is actually access to a donor heart: many patients will die before the organ becomes available. That’s why we urgently need to find ways to increase the suitability of donor organs.”

Although the first heart transplant performed at the Grote Schuur Hospital in Cape Town (South Africa) in 1967 was obtained from a DCD donor, the technique was abandoned and replaced by heart transplants obtained from donors whose death was confirmed using neurological criteria ( Donation after brain death, or DBD) — in other words, their brain has completely stopped working.

Until recently, heart transplants worldwide were still only performed with organs obtained from DBD donors. However, in recent years, heart transplants from DCD donors have become a clinical reality around the world thanks to years of research conducted at Cambridge.

DCD is the donation of organs by patients who are tragically ill with an incurable disease. These patients are usually unconscious in hospital intensive care and dependent on ventilation. Detailed discussions take place between doctors, specialist nurses and the patient’s family and if the family agrees to donate the organs, the process begins.

After the treatment is withdrawn, the heart stops beating and begins to damage its tissues. After 30 minutes, this damage is believed to be irreparable and the core unusable. To prevent this damage, at the time of death, these non-beating hearts are moved to a portable machine known as an Organ Care System (OCS) where the organ is perfused with oxygenated blood and evaluated to see if it is suitable for transplantation.

The technology was pioneered by the Royal Papworth Hospital NHS Foundation Trust in Cambridge, where its transplant team performed the first DCD heart transplant in Europe in 2015. Since then, the Royal Papworth has become the largest and most experienced heart transplant center in the world.

DCD heart transplantation started simultaneously in Australia, followed by Belgium, the Netherlands, Spain and the USA. According to GODT, 295 DCD heart transplants were performed in these six countries in 2021.

Organ care systems are expensive, costing about $400,000 per device plus an additional $75,000 for consumables per organ filled. An alternative, and more cost-effective, approach is known as natural thoracic and abdominal thermoreperfusion (taNRP). This involves perfusion of the organ On site in the body of the donor and costs about $3,000. Its use was first reported in 2016 by a team at the Royal Papworth Hospital.

In a study published in Clinical medicine, an international team of clinical scientists and cardiologists from 15 major transplant centers around the world, including the UK, Spain, USA and Belgium, looked at the clinical outcomes of 157 DCD donor hearts healed and transplanted from donors undergoing taNRP. They compared these results to 673 DBD heart transplants, which represent the “gold standard”.

The team found that overall, using taNRP significantly increased the pool of donors, resulting in a 23% increase in the number of heart transplants performed.

Sir Stephen Large, Consultant Cardiothoracic Surgeon at the Royal Papworth Hospital and lead researcher, said: “Withdrawal of life support from a patient is a difficult decision for both the families and medical staff involved, and we have a duty to respect the donor’s wishes as best we can. For the time being, One in ten hearts recovered is rejected, but restoring heart function in situ can help us ensure that donor hearts find a recipient.”

The survival rates were comparable between DCD and DBD heart transplantation, with 97% of patients surviving for more than 30 days after DCD heart transplantation, 93% for more than a year and 84% of patients surviving after five years.

Professor Philippe Riga, Head of Clinic at the Department of Cardiac Surgery, UZ Leuven, Belgium, said: “This promising new approach will allow us to offer heart transplantation, the last resort, to many patients who need a new heart.”

Researchers say some of the benefits from TanRP are likely due to the reduced amount of time the heart does not receive oxygenated blood, known as its warm ischemia time, when compared to direct ischemia (that is, when the heart is removed immediately for transplantation, and perfused outside the body). . The average time was 16.7 minutes, which is far less than the 30 minutes associated with permanent damage to heart cells.

An added benefit of this approach is that it allows medical teams to preserve many organs simultaneously, such as the liver, pancreas, and kidneys, without the need for multiple organ-specific external perfusion devices. This reduces complexity and costs.

Professor Ashish Shah, Chief of Cardiac Surgery at Vanderbilt University Hospitals, Nashville, USA said: “Heart transplantation has been and always will be a unique international effort. The current study is another example of effective international collaboration and opens up new frontiers, not only in transplants, But in our basic understanding of how all hearts can be saved.”

Dr Beatriz Domínguez Gil, Director General of the National Transplant Organization of Spain, said: “The results of this collaborative study bring hope to the thousands of patients in need of a heart transplant every year around the world. Our findings reveal that heart DCD-based transplants can perform taNRP results in outcomes at least comparable to the gold standard and increases hearts available for transplantation in a way that contributes to the sustainability of healthcare systems.”

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