Darvall was seriously injured in a car accident on Main Road in Observatory, Cape Town. She and her family were visiting friends for afternoon tea and went shopping for cake. They were run over by a drunk driver who failed to see them.
Darvall sustained a skull fracture and severe head injuries, after the car flung her across the road and her head hit the wheel cap of her own car.
She could not stay alive without life support, and was essentially brain dead. At 9 p.m. on the day of the accident, the resuscitation team stopped trying to revive her.
Surgeons had a serious ethical problem because death then could only be declared by whole-body standards. The Harvard Criteria of Brain Death was not developed until 1968, nor was it adopted in South Africa or elsewhere for some years.
The problem in this case was that, although Denise"s brain was damaged, her heart was healthy.
Various reports over the years attributed conflicting reasons for her heart stopping. Foreign forty years, Barnard"s brother Marius kept a secret: that rather than wait for her heart to stop beating, at Marius’s urging, Christiaan had injected potassium into Denise’s heart to paralyze it and thus, to render her technically dead by the whole-body standard. After her father gave his consent, Darvall"s heart was donated to Louis Washkansky.
Her kidneys were given to 10-year-old Jonathan van Wyk.
Due to the apartheid era, the kidney donation to Van Wyk was controversial because he was coloured, while Denise was white.