When Auckland mum Alison Whybro got a call to say her then 10-year-old daughter Isabella was having a cardiac arrest at school it was like déjà vu.
"I could hear the terror in the teacher's voice and I was just in shock," Whybro told the Weekend Herald.
Her eldest daughter Anna, 22, lives with a genetic heart disease called hypertrophic cardiomyopathy (HCM), which interferes with the blood flow out of the heart.
Shortly after that terrifying phone call three years ago, Whybro discovered her youngest daughter also had the condition.
Together, the sisters get each other through. Their mum credits the Heart Foundation for helping to keep her two precious daughters alive.
The family are speaking up to raise awareness about the "horrific disease" amid the Heart Foundation's Big Heart Appeal running yesterday and today.
Every year, more than 6500 New Zealanders die of heart disease - it's the country's biggest killer.
HCM is the most common heart-related cause of sudden death during intense exercise.
The condition is caused by abnormal growth of the muscle cells making the heart wall thicker and reducing the heart's ability to pump properly.
For Anna, her diagnosis came at the age of just 2 after undergoing open heart surgery for a heart murmur.
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Looking back, Anna says her childhood wasn't like most.
"There were days when I couldn't make it up the stairs and I couldn't play sports at school like other kids."
Now, Anna says her biggest challenge is tiredness and coming to terms with alternative fertility options as there was a high chance her offspring would also have the disease.
At the age of 9, Anna had a second round of heart surgery to repair the heart valve.
The operation was a success but, seven years later she collapsed at home.
She immediately underwent another operation to insert a special heart pacer device called an implantable cardioverter defibrillator (ICD).
An ICD is a battery-powered device placed under a person's skin to keep track of their heart rate.
Wires connect the ICD to the heart and, if a potentially life-threatening heart rhythm is detected, it will deliver an electric shock to restore a normal heartbeat.
For Isabella, the device saved her life.
After Isabella's first cardiac arrest, she was rushed to Starship children's hospital and underwent an operation a few days later to insert her own ICD.
Then in November last year, Isabella had a second cardiac arrest at school and fell unconscious.
"Fortunately, her ICD kicked in and restarted her heart. We are very grateful that both girls now have these devices as it gives us some peace of mind," Whybro said.
She said her eldest child Adam, 24, had also been monitored over the years.
"While he shows no symptoms, he too recently underwent genetic testing to find out if he has the HCM gene. He is currently awaiting the test results," Whybro said.
The girls' heart problems had taken a huge emotional toll on the family, Whybro said.
"The condition has caused us an incredibly significant amount of stress and worry, mainly because of its unpredictable nature and the constant underlying possibility of a further sudden cardiac arrest occurring," she said.
Whybro said just as important as the ICD implants was the emotional support provided by organisations such as the Heart Foundation.
"It's wonderful to know that there are dedicated and professional people who give their time to provide education and research to improve the heart health of all New Zealanders.
"With research and education, the next generations also benefit – it's a wonderful legacy that the Heart Foundation is a part of," Whybro said.
The Heart Foundation's medical director Gerry Devlin said not only do one in five New Zealanders die from heart disease, but more people than ever before are living with a heart condition.
"And it's not just the elderly who are at risk. One in five people admitted to hospital with heart disease are under 60," Devlin said.
The Heart Foundation is New Zealand's leading independent funder of heart research and, since 1968, has funded more than $70 million in research and specialist training for cardiologists.
"Funds raised during the Big Heart Appeal will be used to support this research and training programme," Devlin said.
• To learn more about the Heart Foundation or to make a donation visit: www.heartfoundation.org.nz
About heart disease in New Zealand:
• Heart disease is New Zealand's single biggest killer, claiming the lives of more than 6500 New Zealanders every year – that's one person every 90 minutes.
• About 186,000 New Zealanders are living with heart disease.
• The Heart Foundation has funded more than $70 million in research and specialist training for cardiologists since established in 1968.
About Hypertrophic Cardiomyopathy (HCM):
What is it?
It's a condition that interferes with the blood flow out of the heart, and is the most common heart-related cause of sudden death during intense exercise.
What causes it? It's a genetic disorder caused by abnormal growth of the muscle cells that make up the heart wall, which makes the heart wall thicker and reduces the heart's ability to pump properly.
How is it treated? Treatment options include implanted pacemakers to help the heart maintain a normal rhythm, and in some cases operations to reduce the obstruction to blood flow.