An elephant's heart can weigh up to 27 kg, according to the International Elephant Foundation. So, if one stops, it's a big problem to get it going again.
Volunteers in Thailand's Khao Yai National Park were faced with the mammoth task of resuscitating an adult Asian Elephant. The mother and calf had become stuck in a drainage ditch in the park, north of Bangkok, during heavy rain last week.
"The mother elephant was so stressed that she was paralysed," said the Department.
The elephant had to be tranquilised and winched out of the sewer, with help from the local fire department, heavy machinery and volunteer veterinarians.
Footage from the scene shows it was a complex rescue process in heavy rain.
Having winched the drugged elephant out of the hole to their horror, she was no longer responsive. Quick thinking rescuers from Khao Yai jumped into action and began trying to revive the stunned pachyderm.
It took two rescuers climbing on top of the elephant and jumping to perform cardiopulmonary resuscitation (CPR) to bring her round. The dramatic giant medical emergency was captured on video by park volunteers.
"The elephant fell unconscious into the drain after being darted, hitting her head. First aid was needed to save her life," said the National Park.
Eventually the mother regained full consciousness and was reunite with her calf and the rest of the herd.
Dr Chananya Kanchanasarak, Khao Yai national park Department vet, told Sky News it was "one of the most memorable rescues we've done".
The Department of National Parks and Wildlife Conservation thanked the volunteer vets whose quick thinking saved the life of the animal.
"Thank you to the staff of the Conservation Department at Khao Yai National Park. We thank the volunteers, including the people's brothers and sisters, who provided assistance to the fullest extent and did not stop until the mission was successful," said a spokesperson of the Wildlife Conservation Division.