In a groundbreaking study published in Frontiers in Cardiovascular Medicine, researchers have made a significant advancement in heart transplant preservation, offering new hope for transplant patients worldwide. The study demonstrates the successful preservation of pig hearts for over 24 hours using a technique called normothermic ex-vivo heart perfusion (NEHP). This method, which keeps donor hearts in a near-physiological state, has the potential to revolutionize the field of transplantation by extending the viability period far beyond the current six-hour window.

The research team, led by Dr. Robert Bartlett from the Extracorporeal Life Support Laboratory at the University of Michigan Medical School, has been working for the past seven years to extend the shelf-life of donor hearts through improvements to NEHP. Previous experiments revealed that a critical step in the process is filtering the perfusate to remove molecules smaller than 26 kilodalton.

In their latest study, the team successfully preserved the hearts of 30 immature and 10 juvenile pigs for various durations using experimental variants of NEHP. They compared the effects of three different modifications to standard NEHP: hemofiltration to continuously purify the perfusate and remove toxins, plasma exchange to continuously exchange the plasma component in the perfusate, and intermittent left atrial perfusion (iLA) to test the heart's ability to eject blood.

Real-time monitoring of the preserved hearts' health was carried out by visually checking contractility, rhythm, color, and edema, as well as measuring lactate concentration every hour. The control group hearts, preserved without modifications, all died between 10 and 24 hours after removal from the donor. However, all hearts that underwent modifications to NEHP survived for the full 24 hours.

Dr. Bartlett noted that the impact of these modifications on heart preservation beyond 24 hours is yet to be determined. He suggested that plasma exchange may be more effective in removing larger toxins, while iLA could be beneficial for preserving hearts with injuries or borderline function in the donor.

The potential implications of this research are vast. By extending the preservation time, this method could increase the availability of donor hearts, overcoming logistical limitations. Additionally, it could provide an objective assessment of each potential donor heart's viability, reducing the number of unused hearts due to uncertainty about their functionality inside the donor.

The major hurdle for clinical application will be validating these methods in humans. The research team has already begun working with human hearts rejected for transplantation to further explore the potential of NEHP.

Heart transplantation is a critical medical procedure with thousands of people worldwide in need of a new heart. This breakthrough in heart preservation brings hope for a future where more hearts are available for those who need them the most, ultimately saving more lives.

The groundbreaking study opens up new possibilities in the field of transplantation and represents a major step forward in improving the outcomes for transplant patients. With further research and validation in human hearts, the NEHP technique could soon become a standard practice in heart transplantation, providing new opportunities for patients in need and bringing new hope to countless lives.