Some 11 years ago, Anna Bagenholme, a 29-year-old skier survived an accident despite her heart stopping and not being revived for three hours.

Her body temperature dropped to 13.7C (56.7F) making it the longest and coldest cardiac arrest on record.

This extreme cold enabled her miraculous recovery and is inspiring new surgical techniques explored in Horizon: Back From the Dead on BBC Two on Monday 27 September at 2100 BST, or watch again on the BBC iPlayer.