The Waiuku man, who will celebrate his 70th birthday in October, has returned to thank his rescuers, whose tenacity meant that he is likely to be the first person to have survived a cardiac arrest on the mountain.
Gadd revealed that he was walking the Tongariro Crossing in the remote slopes of Mt Ngauruhoe on February 18, when he suffered the attack, according to online reports.
"He was literally dead for 25 minutes. The truth is there have probably been heaps of people who have cardiac arrested on that mountain, but I''''ve never heard of any surviving," said More, who rescued Gadd.
Gadd has two friends of his accompanying him on the walk.
"We had actually stopped for a rest while my friend Colin, who has diabetes, checked his blood sugars."
"I suddenly felt dizzy and got sharp pains in my chest. I knew I couldn''''t go on and we called 111," Gadd said.
Gadd was rescued by St John paramedic, Tony More with pilot Nat Every and crewman Barry Shepherd.
More, a former outdoor pursuits instructor, was also chosen for the job because of his mountaineering experience.
"There was low cloud over the top of the mountain, so we knew we would have to be dropped in and walk in on foot. But we got diverted when the call came in about a man with chest pain.
"I gave him aspirin, but he said the pain was getting worse and just as I turned to get something from my drug roll, he arrested," More said.
"I had the shock box in the backpack and Darryl [Jones] started doing CPR while I defibbed and gave him drugs. After three shocks, we got a pulse back and he started breathing again."
More revealed that even the weather was getting dicier as the clouds started to roll down the mountain
"I was praying they would be able to land again. The weather can change so quickly up there," he said.
However having stabilised his patient, More and the rescue personnel carried Gadd to the waiting helicopter.
"But he arrested again as he went into the helicopter, so we did CPR all the way down to the [Mangatepopo] car park, where we got him into an ambulance and carried on for another 20 minutes and we finally got him back," said More.
After being stabilized at Taupo Hospital, Gadd was transferred by Westpac Waikato air ambulance to Waikato Hospital, where tests revealed minor damage to his heart.
Gadd revealed that it took more than two months to get over the damaged cartilage in his chest .
Last weekend, the retired New Zealand Steel systems specialist and his wife, Maxine, met his rescuers
"It was wonderful. I thank all of them. They all played their part and gave me a second chance. We are so grateful."