On the day Rush was brought to the hospital, none were available. As the minutes passed, the situation became more and more critical.
‘The prospective recipient went into terminal shock at approximately 6 p.m., with a blood pressure of 70 and virtually without respiration except for the continued use of the mechanical ventilation through a tracheotomy tube’, Hardy later recalled in his memoirs. ‘Death was clearly imminent and it was obvious that if heart transplantation was to be performed, it had to be done at once’. 
Rush was wheeled into the operating theatre, where Hardy polled his surgical team about whether or not a transplant attempt should be made using a chimpanzee’s heart.
‘I polled each of the five primary members of the transplant team individually, and their votes were recorded. Four voted to proceed with transplantation… The fifth abstained’. 
The surgery went ahead even though everyone in the room was ‘well aware that any transplantation of a heart in man would be followed by public consternation’ and that ‘the use of a chimpanzee heart would augment the criticism immeasurably’. Hardy later described it as a ‘profoundly sober moment for all’. 
Several hours later, Hardy and his team made history by performing the first ever heart transplant. The chimp’s heart beat for 90 minutes inside Rush’s chest, but unfortunately proved too small to keep its new human body alive. Hardy’s patient died shortly after the operation was complete.
Hardy’s decision to use a chimpanzee’s heart fell under immediate attack from both the public, as well as those within the medical community. The operation ‘precipitated intense ethical, moral, social, religious, financial, governmental and even legal concerns’, Dr. Hardy wrote years later. ‘We had not transplanted merely a human heart, we had transplanted a subhuman heart’. 
Undeniably, the heart is one of the most vital organs in the human body. Without it, we would die. However, the controversy that arose in the 1960s when Hardy implanted a chimpanzee’s heart into Rush had less to do with physiology than it had to do with philosophy. For thousands of years, the heart was considered to be the seat of the human soul. Over time, the scientific community came to recognise the role the brain played in human consciousness. Nevertheless, people continued to equate emotions with the heart. Indeed, to some extent, we still do this today.
The ‘criticism from the media and our peers was vicious’, Hardy’s daughter remembered. ‘Many believed that if you transplanted the heart, you transplanted the soul. Even at school, we were aware that people were upset. As a child, it was difficult to understand why’. 
Hardy’s systematic murder of chimpanzees for use of their organs was also controversial. Invited to speak at a surgical conference in New York City several days after the historic operation, Hardy was shocked when the moderator introduced him by saying: ‘In Mississippi, they keep the chimpanzees in one cage and the Negroes in another cage, don’t they, Dr. Hardy?’ 
Over the next several months, some of the criticism within the medical community waned after Hardy published a paper in the Journal of the American Medical Association in which he described the strict ethical guidelines he and his team had followed when evaluating both donor and recipient. [Note: for more about the use of animals in medicine, click here].
It wasn’t until 1967 that the first human-to-human heart transplant took place at the Groote Schuur Hospital in Cape Town, South Africa, where a young surgeon named Christiaan Barnard was experimenting with pioneering surgical procedures. Barnard’s patient was 55-year-old Louis Washkansky, who was suffering from incurable heart disease. Washkansky could either wait for death, or risk undergoing surgery.
‘For a dying man it is not a difficult decision because he knows he is at the end’, Barnard later recalled. ‘If a lion chases you to the bank of a river filled with crocodiles, you will leap into the water convinced you have a chance to swim to the other side. But you would never accept such odds if there were no lion’. 
So the surgeon and his patient waited for the right moment. Then one day in early December, a woman named Denise Darvall was brought to Barnard’s hospital after incurring fatal injuries in a car accident. She and Washkansky shared the same blood type; her heart was still healthy. On the 3rd, Barnard prepped his patient for surgery. Over the next 5 hours, he would successfully replace Washkansky’s diseased heart with Darvall’s healthy one.
Washkansky’s new heart beat strongly and steadily. Unfortunately, due to a suppressed immune system, he contracted double pneumonia and died 18 days later. Nevertheless, his case would signal a turning point in the history of medicine.
Years later, Barnard recalled how the landmark surgery changed his life: ‘On Saturday, I was a surgeon in South Africa, very little known. On Monday, I was world-renowned’.  Barnard, more than Hardy, was celebrated for his accomplishments, appearing on the covers of magazines and touring the world with stories of his success.
Christiaan’s brother, Dr Mario S. Barnard, published a paper in the South African Medical Journal describing the historic operation. In it, he credited Hardy and the Mississippi team for paving the way, arguing that this earlier operation proved that ‘the feasibility of cardiac transplantation was now irrefutable’. 
Even after the first successful human-to-human heart transplant, surgeons continued to experiment with animal hearts. Between 1964 and 1977, sheep, baboon and chimpanzee hearts were transplanted into at least four adults, all of whom died within a few days of the operation. It wasn’t until 20 years after Hardy’s operation on Rush that surgeons were somewhat successful with a cross-species heart transplant.
On 14 October 1984, Stephanie Fae Beauclair was born prematurely with hypoplastic left heart syndrome, a rare congenital defect in which the left ventricle is severely underdeveloped. Baby Fae’s parents took her to Loma Linda University Medical Center in California, where they met with Dr Leonard Bailey.
‘In those days, the advice to parents was to leave the baby here to die or take it home to die’, Bailey recalled. 
Bailey, who had performed more than 150 heart transplants on various species over the past 6 years, offered the grief-stricken parents a second option. He proposed replacing their daughter’s defective heart with that of a baboon. On 26 October 1984, Bailey and his surgical team did just that.
Baby Fae lived for 21 days, two weeks longer than any previous baboon heart transplant recipient. At a news conference following the child’s death, Bailey told reporters: ‘Infants with heart disease yet to be born will some day soon have the opportunity to live, thanks to the courage of this infant and her parents’. 
Shortly after this feat, surgeons abandoned inter-species heart transplants due to the high risk of infection that followed such operations.
Today, approximately 3,500 human heart transplants are performed annually worldwide. The vast majority of these are done in the United States. Due to the development of powerful anti-rejection drugs, 85% of patients survive up to one year after surgery; 75% make it to their third year.
And it all began on 23 January 1964 with the heart of a chimpanzee.
1.James Hardy, According to The World of Surgery 1945-1985: Memoirs of One Participant.
5. Quoted in Lynne Jeter, ‘Having a Heart-to-Heart’, Mississipi Medical News (2008).
6. Quoted in Tony Stark, Knife to the Heart: The Story of Transplant Surgery (1996), p. 162.
7. Quoted in D. McRae, Every Second Counts: The Extraordinary Race to Transplant the First Human Heart (2007).
8. Quoted in Fred C. Pampel & Seth Pauley, Progress Against Heart Disease (2004), p. 78.
9. M. S. Barnard, ‘Heart Transplantation: An Experimental Review and Preliminary Research’, South African Medical Journal (30 December 1967), p. 12.
10. Quoted in Ansel Oliver, ‘Surgeon Bailey Reflects 25 Years After “Baby Fae”’, Adventist News Network.
11. Quoted in Claudia Wallis, ‘Medicine: Baby Fae Loses Her Battle’, Time Magazine (26 November 1984), p. 88.