In 1984, at Loma Linda University Medical Center in California, Doctor Leonard L Bailey performed the world’s first baboon-to-human heart transplant – replacing a 14-day-old infant girl’s defective heart with the healthy, walnut-sized heart of a young baboon.

Stephanie Fae Beauclair, known as Baby Fae, was born with hypoplastic left-heart syndrome, a deformity found in newborns in which part or all of the left side of the heart is missing – and which can be fatal.

A few days after her birth, Dr Bailey convinced Baby Fae’s mother to allow him to try the experimental baboon heart transplant. Three other humans had received animal heart transplants, the last in 1977, but none survived longer than three days. Bailey argued that an infant, having an underdeveloped immune system, would be less likely to reject alien tissue than an adult.

Baby Fae survived the operation, and her subsequent struggle for life received international attention. "The technical features of it all went well," Dr Bailey later said. "She was waking up, a couple days later she was off the ventilator, eating."

As Baby Fae recovered, news spread around the world, bringing the media and protestors to the medical centre. “The media scrutinised Dr Bailey and everything he did,” said Marie Hodgkins, a nurse who managed the cardiothoracic unit Baby Fae was on.

Dr Bailey told The American Medical News: “In disorders like Baby Fae's, a baboon heart not only may be justifiable, it actually may be preferable to a human heart.” He added: “We're optimistic that within three months, she'll be able to go home.”

Sadly, that never happened. After living longer than any other human recipient of an animal heart, Baby Fae’s body made a concerted effort to reject the alien transplant. Doctors were forced to increase dosages of an immuno-suppressive drug, leading to kidney failure. Ultimately, they were defeated by the swift onset of heart failure – and on November 15, after holding on for 21 days, Baby Fae died.

Within a year, Dr Bailey had performed the first infant-to-infant heart transplant on Baby Moses, whose actual name is Eddie. Now 30 years old, Eddie holds the distinction of being the oldest living infant heart transplant recipient. “Much of what we learned from Baby Fae's operation we were able to apply to the first successful infant-to-infant heart transplant just over a year later in November 1985,” said Dr Bailey.

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The surgeon’s actions were criticised by many, however, on both ethical and medical grounds. The American Medical Association said that his assertion that Baby Fae’s death was not related to the species of her donor was “wishful thinking” – and that a newborn’s immune system “is intact, inexperienced and in some ways functionally deficient, but it is capable of the rejection response” in the same way that an adult’s is.

But, said Dr Bailey: “The bottom line is Baby Fae's legacy is a strong one – there have been several thousand babies salvaged now who would not (have made it) otherwise.

“I think she sent word around the world that people should think about newborns.”