The 16-year-old has surgery at the Royal Victoria Hospital for Sick Children when she just was 10 days old, then again at two-and-a-half and had her final operation aged six.
The budding singer-songwriter said that the new app, created by the Children's Heartbeat Trust and Belfast Trust, would be vital in preparing young people to take on the responsibility of taking care of themselves as they become an adult.
The program can help them manage their medication, find out more about their condition and keep in contact with their doctors and medical team, encouraging ownership and understanding of their own health needs.
Although having a congenital heart defect can be extremely difficult to deal with and can make life extremely tough, the new technology can help people make the transition.
"Apart from my operations, my appointments and my medication, I am and always have been generally very well for a great period of my life," said Hollie.
"I have always had some fears regarding hospital appointments - and especially needles - but I tend to live a very happy and fulfilling life, and I have just recently completed my GCSEs.
"I have also been extremely lucky to have had the best cardiologist, Dr Brian Craig.
"From being a tiny baby until the age of 16, he has always been a constant source of reassurance, guidance and support for both me and my mum. I have come to - and always will - trust him with my life, and I have always felt safe in his care.
"I really feel that teenagers need to gradually have information and control as they get older and begin to learn more about their heart and the impact that it has on their lives as individuals. Now at 16, I do feel empowered and therefore a lot less afraid, which is big coming from someone who is scared of almost everything. I no longer feel vulnerable and I now realise that, actually, it is my choice and my decision to determine what happens regarding my own physical health because, put very simply, it is my body.
"It also really helps that the medical staff now speak to me about everything rather than looking to my mum for answers on how I have been.
"But with this comes responsibility, which, as we all know can also seem frightening at first. The teens app, in my opinion, can help to prepare young adults for the transition.
"Things such as finding out who is part of the clinical team and the roles that they play can make a massive impact.
"Sometimes, it is the simplest things that can help a lot.
"The app can also help with a medication reminder - something I know I'll use as I take medication three times a day.
"In general I feel that the app will be a great tool for teenagers to access information that is correct and up-to-date, and it will make the process of transition much easier."
Hollie's mother, Claire (42), also said that the app would help reassure families and teenagers in the future.
"It can be daunting at that stage of life when you realise the seriousness of having a heart condition because you don't really understand it when you are eight or nine as your mother or father looks after you," she explained.
"But when you are a teenager, you have to start making decisions for yourself."
Claire said knowing Hollie had the medication reminder helped the two maintain a good relationship as she did not have to tell her what to do.
"You want them to make an informed choice based on correct information," she added.
"The app will tell them if they drink alcohol on certain medication what the affect would be. The reminder works by typing in the medication used, and it beeps like an alarm when it should be taken. It is another tool for them to get the right advice.
Thirty years ago the prognosis for children with heart conditions wasn't very good. This will help so many teenagers in the future."
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