乌鸦传媒

Hearts donated after circulatory death (DCD) yielded comparable rejection episodes and survival outcomes as those from brain-dead donors, an Australian study showed.

Of the 45 eligible DCD donors, all 23 hearts transplanted were successfully implanted, reported Kumud Dhital, PhD, of the Heart Lung Clinic in Sydney, and colleagues in the .

At 4 years, mortality was 4.4% -- one death day 6 after the operation in one of the eight cases that required extracorporeal membrane oxygenation (ECMO).

All surviving patients maintained their status in New York Heart Association functional class I with normal biventricular function, and no evidence of acute rejection on discharge and normal cardiac function based on echocardiogram, the researchers added.

Nine patients needed post-transplant mechanical circulatory support for primary graft dysfunction (PGD), which called a high incidence among the otherwise "excellent" survival outcomes.

Nevertheless, it's a substantial advance toward expanding the heart donor supply beyond the current brain death criteria enacted in 1981, noted editorialist Francis Pagani, MD, PhD, of the University of Michigan in Ann Arbor.

"These data add to the growing experience of DCD heart donation that should provide a stimulus for such efforts in the United States," he wrote.

Warm ischemic time a key determinant outcome for DCD in the recovery of heart, Dhital's group noted. "The need for post-transplant mechanical circulatory support rises when the asystolic to cardioplegia (AP) time exceeds 12 min."

Although there has been significant experience with DCD transplantation of kidneys, livers, and lungs in the U.S., DCD heart transplantation remains clinically challenging. A substantial clinical and ethical framework for DCD heart donation in the U.S. has been developed by "groundbreaking" work in the U.K. and Australia, Pagani highlighted.

This particular experience in Australia demonstrates the feasibility of doing this, and it opens up the opportunity of doing it here in the U.S., noted Pagani in an interview. "Now if you add the DCD donor pool on top of the existing brain death donor pool, there's a possibility that it could increase the supply of donors," Pagani told 乌鸦传媒.

"Because of the dire need for donor hearts, it is clinically necessary to resolve these controversies and challenges to expand the current heart donor pool in the United States," Pagani said.

The researchers reported on their experience attending to 45 DCD heart retrievals, of which 33 were procured and 23 hearts were transplanted. Twelve donors were not used because they did not go on to circulatory arrest within the pre-determined time frame (30 minutes).

The transplant program for DCD hearts used direct procurement with the heart connected to an ex vivo perfusion system for reanimation and evaluation for transplantation using biochemical assessments of lactate metabolism.

Two hearts weren't used due to malfunction of that perfusion system machine malfunction. Eight hearts did not meet the viability criteria during normothermic machine perfusion.

There were six female and 17 male recipients with an average age of 52 years.

Pagani pointed out that the best conditions under which to take a DCD heart still aren't really known and that the technology isn't ideal.

"It doesn't allow us to assess how strong the heart is beating," he noted. "You have to measure metabolites of the heart to assess whether its functioning well or not, so that's an indirect measurement and not really as equivalent as measuring how strong the heart beats. So you are taking a chance on a heart that may look okay and all the biochemical tests say it's okay, but it may not be contracting very strong."

Other limitations Pagani noted that could hamper wider implementation include significantly higher cost and resource utilization, as the Australian experience required two surgeons, a perfusionist, an anesthesiologist, and a transplant coordinator to travel to the donor hospital, along with the perfusion machine.

"In the United States, such costs and utilization of resources will likely initially limit DCD heart donation to larger medical centers capable of absorbing such costs that may inadvertently lead to greater regional disparities in access to heart transplantation in the United States," he wrote.

Looking ahead, more research is needed "to improve the efficiency of donor heart harvesting and transport and to identify better methods to measure ventricular function in transplanted hearts," the study authors wrote.