Sydney Rippy heads off to kindergarten this fall. Big sister Madison starts third grade.

These teary-eyed family milestones are part of a greater survival story.

The Blaine sisters both received heart transplants around age 3.

Diagnosed with the same rare heart defect, Madison had her transplant in August 2009 and Sydney hers in April 2012, both performed by Mayo Clinic doctors. The Star Tribune previously told their story in May 2012 and July 2013.

"They are miracles, for sure. So far so good," said mom Linsey Rippy, as the girls played and chattered in the background last week.

During the past three years, Linsey, husband Noel and the girls have focused on staying well, relishing the simple joys of childhood and helping out other Mayo families. The highlight of the past two years has been two Make-A-Wish trips to Disney World. In Florida, the family stays at the Give Kids the World storybook resort for children with special needs, where Halloween, Christmas and birthdays are celebrated each week.

"It's amazing. It's the most magical place," Linsey Rippy said.

At home, the girls prefer to play with toy tools, trucks and their iPads vs. dolls. They enjoy swimming in grandpa's pool, trips to the playground, playing with their aunt and with each other.

"Some days they play together like angels and other days it's a royal rumble," Linsey Rippy said.

Sydney, 6, and Madison, 9, have a typical sibling dynamic but their childhoods are rife with unconventional challenges.

Doctors diagnosed the girls with dilated cardiomyopathy that impedes the heart's ability to pump blood efficiently. It can cause sudden cardiac arrest and required the transplants. The new hearts will extend their lives, but there is no such thing as "fixed," explains their mother.

The sisters must navigate a lifetime of expensive anti-rejection medicines that lower their immunity, doctor's appointments and limitations on their activities. Both girls might also need additional heart transplants as teenagers. The anti-rejection drugs are hard on kidneys, making kidney transplants a possibility, too.

In January, a bout of pneumonia resulted in a three-week hospital stay for Sydney.

Both girls cope with developmental delays resulting from brain damage related to their heart problem. They will spend most of their school day in special education classrooms.

Linsey Rippy said ongoing medical, educational and financial worries weigh heavily on her mind.

"Sometimes it's so … hard," she said. "We try not to play the pity party game."

Linsey Rippy stays home with the girls, managing their health care, while Noel is a carpenter.

The family travels to Mayo Clinic every three months for blood work and checkups. The 200-mile round trips are a strain but the reassurance that the girls are OK is worth it.

"[Doctors] just want to be sure if there is any little inkling of some problem, they are going to catch it. It's peace of mind for me. Doctors saying, 'Everything looks great.' It never gets old hearing that," Linsey Rippy said.

Doctors suspect the girl's heart problems are rooted in genetics, but so far have been unable to make that link.

"We have our own little research team that is pulling apart our entire genetic sequence," Linsey Rippy said.

With gratitude and awareness from her experiences, Linsey Rippy has organized eight blood drives. She also organizes a toy drive each Christmas. The gifts and gift cards are distributed at Mayo and the Ronald McDonald House, she said. She estimates collecting $5,000 last year.

"I want my kids to grow up thinking, 'This is what we do. We help people. We volunteer. We give back,' because we wouldn't be anywhere without help from others," she said.