Doctors at Duke University made U.S. history by successfully transplanting a revived heart from a dead adult donor whose blood had stopped circulating, thereby saving another heart patient’s life.
A new technique keeps an organ removed from a lifeless donor healthy and viable for insertion into a recipient by mechanically pumping oxygenated blood and electrolytes through the excised organ while it is being transported to its new host.
Harvesting an organ after the patient has been pronounced deceased is called donation after cardiac death (DCD). The heart surgeons used a machine called the TransMedics Organ Care System (OCS) to bring the unbeating heart back to life for transplantation.
This is a game-changer because about 20 Americans on the transplant waiting list (which numbers more than 100,000 people) die every day before they can receive treatment. The ongoing shortage of donor hearts is caused by the high failure rate of sustaining a removed organ after it has been cut off from its vital blood supply.
Dr. Jacob Schroder, one of the lead physicians in the landmark case, said that, currently, donated transplant hearts come from patients declared brain dead whose hearts are still functioning. Normally, a donor heart must be taken from a donor whose brain is unresponsive but whose heart continues to pump life-sustaining nutrients into the tissues. This prevents the heart muscle from dying too quickly.
Cardiac tissue begins to die soon after the heart stops beating, making it unfit for transplant. When a heart stops beating naturally, it is typically receiving a reduced supply of oxygen. Consequently, the organ tissue has been starved or is actually dying before circulatory death is pronounced.
DCD transplants patients are not dead medically but do rely on life support to keep their blood circulating and vital organs working.
Such vegetative patients are not expected to rally, as Dr. Schroder explained:
“Although they are not technically brain-dead, their chance of recovery is zero.”
The U.S. Food and Drug Administration (FDA) has approved clinical trials of the TransMedics Organ Care System at Duke and four other national heart transplant surgeries. The technology solves the problem of how to protect a heart cut off from the donor’s blood supply and its cooling effect.
The transplant surgery begins after the donor patient’s life support is withdrawn and the patient dies. After a proscribed five-minute wait time, the patient is officially pronounced dead and the heart is removed.
Using a cutting-edge technology called warm perfusion, the doctors quickly connect the disembodied heart to a series of tubes that pump the donor’s blood back into the excised heart to keep it beating during transport. Pressure and rate of flow can be set to help the donor’s heart recover from being deprived of oxygen-rich blood.
Nurture restored, the heart muscle reanimates and continues expanding and contracting as blood keeps it alive. Schroder said the OCS keeps the donor heart “warm, it beats, and you transport it back and start the transplant process.”
One of the surgeons involved in the historic operation documented the groundbreaking procedure and posted the video on Twitter.
After its cooling blood supply stops, the heart is the bodily organ with the least tolerance for exposure to the relative warmth of a person’s natural body temperature. Even when kept very cold, hearts are typically only viable for 4-6 hours once removed from a donor’s body.
Dr. Schroder added that he and his team had used the OCS to transport hearts from lengthy distances, as well as less viable organs from aging or deceased donors.
With so many more hearts available for transplant, the Duke researcher estimated that the heart transplant waiting list could go down as much as 30 percent:
“At this time, a conservative estimate would be 250,000 people who have end-stage heart failure. Even if you said that only 10% of them could get a transplant, that’s still 25,000 people.”
The limited pool of viable donor hearts dictates how many operations can be performed. “We did 3,100 heart transplants last year due to lack of suitable donors,” stated Dr. Schroder.
Europe and Australia have approved using OCS for organ transplants. Doctors in Cambridge, England, and Sydney, Australia, have reported good results with the life-saving system.
The first successful human heart transplant was performed in 1967 in South Africa. The following year, doctors at Stanford University in Palo Alto, California, were credited with the first U.S. heart transplant operation.
By 2018, over 3,400 hearts had been transplanted in the U.S. We can expect this number to bloom thanks to warm perfusion that maintains organ life support conditions during transport.