He performed the world's first human heart transplant operation on 3 December 1967, in an operation assisted by his brother, Marius Barnard; the operation lasted nine hours and used a team of thirty people.[1] The patient, Louis Washkansky, was a 54-year-old grocer, suffering from diabetes and incurable heart disease.[1][5] Barnard later wrote, "For a dying man it is not a difficult decision because he knows he is at the end. 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." The donor heart came from a young woman, Denise Darvall, who had been rendered brain damaged in an accident on 2 December 1967, while crossing a street in Cape Town.[1] After securing permission from Darvall's father to use her heart, Barnard performed the transplant.