She points to valves and lines and names them, along with how they affect one-year-old Josh's life.
They bring Josh into the kitchen in their Dundalk home. He has the biggest, bluest eyes ever. His twin sister Kim is watching carefully, as Josh tips his little hand in mine.
Josh is one of the luckier babies. He has survived two major heart operations -- cheating death moments after he was born. He smiles. Twins Josh and Kim recently celebrated their first birthday. Sister Alicia Hearty (12) is excited.
"When I was 10 weeks pregnant I was told in Our Lady of Lourdes, Drogheda, that I was carrying twins and it was a good shock," says Mags. "At the 16-week scan one of the nurses said there seemed to be a problem with one of the babies' hearts.
"It all happened so fast," says Mags. They were moved to Our Lady's Hospital for Sick Children in Crumlin.
"Dr Colin McMahon did a scan, then sat us down and told us that one of our twins had a major heart complaint. On a scale of one to 10, Josh was an eight. I couldn't stop crying. Niall was just numb with shock.
"The doctor said Josh's right ventricle was not developed. We were told one in every 100 children has the condition. The hospital said Josh was one of the worst cases.
"They said my son could have a life expectancy up to the age of 15 or 20. All these thoughts went through our heads: will he be able to go to school? Will he be able to play football? We were told Josh would only be able to play gentle games like golf."
At a regular check-up at 34 weeks, Mags was brought in to deliver the twins by C-section. "I was in shock," she says.
She's a diabetic on daily insulin shots. Mags had high blood pressure and Josh's heart beat had dropped. Josh and Kim were born six weeks premature on July 14, 2009. Josh weighed in at 4lbs 3 ounces, just five ounces below Kim.
"When the twins were born, I only got a glimpse of Josh and I didn't get to hold him. He was put into an incubator," says Mags.
"He had his first open-heart operation three days later. The doctors said they couldn't wait. Our only other choice was to take him home to let him pass on. The operation put a shunt into his heart so blood could flow better. We were told Josh was the first child to have such an operation."
The operation was a success and life got into a normal pattern for the family. "I went home with Kim, but we were still up and down to Crumlin to see Josh every day," says Mags.
She got sick with her diabetes. "The shock had hit us like a ton of bricks," she says.
"I got stressed," says dad Niall (33). "I went into a deep depression." Josh arrived home within the next month. "The first time Kim saw her brother, she put his hand on his little chest, his heart, and I just melted," adds Mags.
In June, Josh had his second operation to take out the shunt. "His breathing is better and so is his colour," says Mags.
"When Josh is around two or three years old, he will get the next operation on his heart to help blood flow. He might someday need a heart transplant, but we take one day at a time."
Mags praises the blood donors who helped her son and the new ICU unit in Crumlin. The local hospital in Dundalk is closed.
"It is a disgrace. These kids are our future," she says.