‘Heart in a Box’ a Big Step Forward for Organ Transplants

Medicine  

Until now, hearts used for transplants have usually been extracted from brain-dead patients, and once removed, the organs are also stored and transported in cold temperatures to avoid rapid deterioration. Now scientists have begun using the 'heart in a box' to keep the hearts warm and functioning. This device could increase the pool of donated hearts by between 15 and 30 percent.

Developed by Transmedics, the OCS Heart, often referred to as the “heart in a box,” is a machine that keeps a heart supplied with blood and oxygen for several hours. This allows it to be moved to another patient for transplant. Heart transplants aren’t exactly a new thing—the first one was performed in 1967—but the organ is usually kept on ice while being moved. So why bother keeping a heart beating at all? What does this device do that ice can’t? As it turns out, quite a bit.

Donated hearts almost exclusively come from brain-dead patients: Those whose brains have stopped functioning, but whose bodies can be maintained by a ventilator. In these circumstances the heart is still beating, and is cooled before being removed from the body. At temperatures just a few degrees above freezing, the metabolic rate of the cells is reduced by 90 percent. The organ deteriorates far more slowly, giving doctors time to transplant the heart.

By keeping organs warm and alive instead of putting them on ice, doctors have a much larger window of time in which to perform the transplant.

But not all patients who die in a hospital are brain dead. Sometimes the body gives out first. However, this usually makes things difficult for transplant. By the time the heart stops, the tissue is already starved of oxygen, and the cells are deteriorating quickly. In these cases, the heart is usually declared not suitable for transplant. The OCS Heart could change all that.

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With a fresh supply of oxygenated blood, hearts that have stopped can often start beating again, sometimes even on their own. The OCS Heart has already been used in at least 15 cases in Australia and the United Kingdom. In one case, 26-year-old Lee Hall had been surviving for six years by way of a mechanical pump installed in his body. The pump’s cables became infected, and Hall only had two days to live without a new heart. Fortunately, the OCS Heart was able to revive the heart of a dead donor, and Hall is now recovering at home with his family.

Despite its success abroad, the device is still pending approval in the U.S., where it could increase the number of donated hearts by as much as 30 percent. Currently, around 2,400 heart transplants are performed each year in the U.S., and that number has been the same for the last 20 years. The OCS heart could be the first real breakthrough in transplant technology in decades, which is a very good thing; 21 people die each year because they can’t get the organs they need. However, this breakthrough does come at a cost: namely, $250,000. With Transmedics receiving over $100 million in total funding to develop the OCS Heart, the price is not unjustified, but it still presents a barrier that could prevent many hospitals from acquiring the device.

Transmedics may not be able to maintain that price point for long, however, as a number of similar devices are in development. Organ Assist, OrganOx, and Organ Solution are all working on warm perfusion machines, although not all of them will be making machines for heart transplants. Organ Solution in particular is focused on livers. The U.S. liver transplant waiting list currently has more than 16,000 people on it. With less than 7,000 transplants performed each year, most patients on the list die before ever receiving a transplant.

By keeping organs warm and alive instead of putting them on ice, doctors have a much larger window of time in which to perform the transplant. However, this new technology is not without controversy. The question is whether the death of the patient is truly irreversible if the heart can function again outside the body. Currently the issue is being handled by obtaining informed consent from family members before removing the heart, but as medical technology continues to advance, questions about the line between life and death will only become more complex.

By Daniel Faris

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