"I had a big talk to the nurse. We'd got the medication. I'd paid for it. I'd just put my credit card back in my wallet and then I'm on the floor dead.
"My husband had rung me as I was putting in my Pin number for my credit card and I said to him, 'Look I'll ring you back in two minutes', and the next phone call he got was from the doctors to say, 'Your wife has collapsed'."
The 37-year-old has had to piece together the events of the day from her family. The last thing she remembers is making pancakes for Alex the night before for his birthday the next day.
She told Hawke's Bay Today she had no after-life experience.
"The next thing I remember is waking up 48 hours later in hospital wondering what the hell happened."
She said she was clinically dead for about five minutes and the event had been a traumatic experience, especially for Alex and Olivia who had witnessed the incident.
She credits the pharmacy staff and doctors for keeping her alive by performing cardio-pulmonary resuscitation (CPR) and using a defibrillator until an ambulance arrived.
"The medical profession, they are trained in CPR and all that sort of stuff ... to be having a conversation with someone so young and then I was dead on the floor.
Mum brought back to life after collapse drama
"You know everyone has gone through hell ... I was just lucky I was with medical professionals," Mrs Wrenn said.
"If I had been walking down the streets or anywhere else, it would have been a different story."
She said she had been diagnosed with a rare condition known as Long QT Syndrome, a heart rhythm disorder that can potentially cause fast, chaotic heartbeats and affects one in 7000 people.
"It means part of my heartbeat is too long and lands on the second part and the heart just goes 'stuff you' and stops. That's the easy way of explaining it."
The mother of three -- she also has an 18-year-old son George -- said she was unaware she suffered from the condition.
"With Long QT there is no warning. There is no 'you're not well' or anything like that. It is just 'stuff you, I'm not going to work any more'."
It means she now has a pacemaker and defibrillator implanted in her chest.
She said the condition could be inherited and her children were now being tested to see if they had it.
Although the incident nearly claimed her life Mrs Wrenn said she was using the experience to send a message to the public.
"The whole thing is, yes these people [who saved her] were trained in CPR. But they still had to deal with the shock and everything else.
"If [they] didn't know what to do I would have died. If it was a member of the public who had been there and didn't know what to do they'd be living with it for the rest of their life."
St John Hawke's Bay district operations manager Stephen Smith said Mrs Wrenn was lucky to survive her ordeal
"If this had been an unwitnessed arrest, if she'd only been at home with the children and no one had called an ambulance straight away, no one had started CPR and no one had used a defibrillator, then I would say it would have been a grim outcome. Certainly the fact she had been in a public area, and people had provided that life-saving support she needed, it has contributed undoubtedly to her still being alive."
Mr Smith said the incident highlighted the importance of members of the public learning CPR.
"For us [St John] the success of someone surviving cardiac arrest isn't just up to the ambulance officers. It's up to family members, work colleagues, people in the street who can provide that bridging support for people until and ambulance can arrive."
Mrs Wrenn said all those who helped her that day were "heroes".
For information on correct CPR, visit stjohn.org.nz.
