"That initial contact from the paramedics is really important and that can be a look of concern and reassurance, or it can be a smile saying 'don't worry, we've got this'."
Another time Heke was sent to a cardiac arrest on Kapiti Coast.
He said it was a busy scene with the fire brigade, police and paramedics but in the end they managed to save the patient.
"You get this appreciation of life when you see someone who just opened a car door to go to the supermarket and then fall out because their heart decided to stop."
Heke also spent time with call operators who work in high pressure and often emotional situations to dispatch medical teams to people in need.
He captured one of them in action.
"If you look deep into her eyes you can see the intensity.
"That photograph is just as powerful as any of the other ones that are a bit more action packed."
Heke said he could not always find it in himself to capture moments of intense sadness and defeat.
"A woman was in a real estate agent office, her husband had just left her and she had terminal breast cancer. She was there with her parents to sell the house and she fainted and fell back."
He said their eyes connected but he didn't lift the camera because it didn't feel right.
"There was a man, and his wife was having a miscarriage and he was looking at me and the look on his face was such of despair and worry and I thought this is going to be a really good photograph."
But Heke decided against photographing the desperate man who was almost crying.
"Because of the huge outpour of emotion and his wife lying down on the stretcher with paramedics working on her."
He said he questioned whether he needed to be less sensitive and toughen up but had decided to stand by his decision not to take the pictures.
Heke said he was surprised it was not the most violent situations he encountered that struck a chord with him.
"Injuries heal, you know they will get better. But it's when you look into people's eyes and only see sadness or defeat. That's what sticks to you."