A 15-year-old girl has become the first Canadian to have an artificial heart removed after her own heart healed itself.

Melissa Mills arrived at Edmonton's Stollery Children's Hospital last year after a sudden illness made her critically ill and a candidate for a heart transplant.

Doctors at the hospital implanted the Berlin Heart, a portable mechanical device that keeps blood pumping in an ailing heart, so she could survive until a transplant became available.

But over the next few months, Melissa's overall condition improved dramatically, and her heart muscle regained much of its strength. After 146 days on the Berlin Heart, Melissa underwent surgery to have the device removed.

"We thought the miracle was that the Berlin Heart would give us time to find the perfect donor heart for Melissa," said her mother, Sharon Mills, in a release. "We are overwhelmed that instead, the Berlin Heart gave her own heart time to rest and repair itself."

The Berlin Heart is the world's first mechanical heart designed for children. To date, five patients have received a Berlin Heart at the Stollery Children's Hospital.

Dr. Ivan Rebeyka, clinical leader of the Berlin Heart program, said he's encouraged by the device's role in human heart regeneration. "We are just beginning to understand all the applications for the Berlin Heart," he said.

With files from the Canadian Press