Twenty years ago, Mavis McArdle desperately needed a liver transplant. Her medical team feared she was brain dead and needed to buy some time to make sure that didn’t happen.

They decided to take a pig's liver from a research lab at the Montreal General and hook it up outside of Mavis' body. To their surprise, it actually worked – the pig’s liver functioned as a stand-in for several hours until a human liver became available.

Soon after she got out of surgery, McArdle told reporters she intended to still be around in twenty years.

Friday morning, she was on hand at the Royal Victoria Hospital, where the transplant took place, to celebrate reaching that milestone.

“I believe very much in the power of prayer. I pray every day for my donor and my donor’s family. I also pray every day for the doctors and the nurses that their hands be guided to help other people,” she said.

The procedure was a Canadian first. It's been tried again without success; doctors say Mavis' case really was a miracle.

One of the residents back then went on to spearhead North American research on using animal organs for human transplantation.

“The tools for modifying pigs genetically are improving dramatically,” said transplant surgeon Joseph Tector.

Mavis is now 76 and in good health. She says the greatest gift she ever received is one we are all capable of giving.

“When we're at the end of our days, we no longer need those organs. Why not, pass them on and let someone else live. Maybe someone else could live twenty years like I have,” she said.