The time from when a heart is removed from a brain dead organ donor and transplanted into a recipient is known as the ischemic time. This is a critical period of time since the donor heart is not receiving any blood supply, oxygen or nutrition and if the ischemic time becomes prolonged (beyond approximately 4 to 6 hours), the heart may be damaged to the point that it does not work well in the recipient (known as primary graft dysfunction). For the last 50 years of heart transplantation, transportation of the heart during the ischemic time involves stopping the heart by paralysing it chemically and then putting it in ice slush to cool it down and reduce its energy requirements, a technique known as cold static storage (CSS). Recent advances in donor heart preservation have led to the development of a mechanical perfusion system called non-ischemic heart preservation (NIHP) or hypothermic ex-vivo perfusion (HEVP).

With this perfusion system, the heart can be continuously perfused with a solution containing hormones, oxygen and some nutrition during the ischemic time. Protecting the donor heart using NIHP substantially increases the ischemic time while minimizing the risk of primary graft dysfunction.

The aim of the current trial is to investigate the effectiveness of NIHP to increase the ischemic time of donor hearts to 6 to 8 hours. Findings from this study may demonstrate that NIHP is beneficial in preventing primary graft failure. Additionally, countries the size of Australia and New Zealand where donor hearts are often declined because the ischemic time is unacceptably long, NIHP of the donor heart may allow longer ischemic times and hence increase donor heart availability.