On Monday, Emma joined a friend with POTS, 19-year-old Aubrey Slack, to put the finishing touches on a tree for the Festival of Trees, one of Primary Children's Hospital's main fundraisers.
The tree has a dual purpose: to make money for the hospital where both girls are treated and to raise awareness for the affliction they share.
The festival runs from 10 a.m. to 10 p.m. Wednesday through Saturday at South Towne Exposition Center in Sandy.
The pair connected via social media this fall after news reports about Slack's illness and her photo shoot at Tiffany & Co. in City Creek, done in preparation for the tree festival.
Slack chose a "Breakfast at Tiffany's" theme for her tree because her parents, Julie and Brett Slack, have always told her she resembles Audrey Hepburn, the star of the 1961 movie. The photo being displayed near her tree shows the teen in front of the Tiffany's window, wearing a French twist in her hair, dark glasses and a dress similar to Hepburn's.
On Monday, the two girls helped their parents a bit with the decorating, but more often sat in fold-up chairs because it's taxing to stand for very long. They wore matching tee shirts with the words "Potsie Girl" on the front and the web address for the National Dysautonomia Research Foundation on the back. (POTS is a form of dysautonomia).
Designing and decorating the tree together has given them both a bit of joy, says Brett Slack, who watched his daughter's world change dramatically after she was diagnosed four years ago.
"She can hang on to things like this to help through the hard times," he says.
Emma, who fell ill on Oct. 1, says she's learning the true meaning of an aphorism that hangs on her bedroom wall. It says life isn't about waiting for storms to pass but learning to dance in the rain.
"Now when I read it, it means living through the bad times," she says.
'People don't believe them' • POTS was first recognized about 15 years ago and it is increasingly on the radar screen for pediatricians and other doctors, says Susan Etheridge, a pediatric cardiologist at Primary Children's.
She sees roughly two new patients every month; sometimes their primary doctors have mistaken POTS for chronic fatigue or thought they had a "whiny teenager" as a patient. (There is also an adult form of POTS).
There is no cure and little understanding of what causes the syndrome, she says. It sometimes occurs during puberty, and can be triggered by surgery or bouts of illness. It afflicts girls more often than boys.
But it isn't fatal and many grow out of the symptoms gradually as they become adults, Etheridge says.
POTS patients have to drink lots of water, take salt supplements and wear compression hosiery to keep blood from pooling in their lower extremities.
Physical exercise the very thing fatigued sufferers want to avoid is important for improving circulation, Etheridge says.
"Increasing the tone and strength of lower body muscles helps blood get back to the central body," she says.
Drugs to lower or raise blood pressure often help, she says. Beta blocking drugs to lower the heart rate also are often prescribed.
"Psychologically, one of the problems these kiddos have is people don't believe them," says the cardiologist. "They don't look sick. They look pale."
'Make a difference' • When Slack first became sick after a bout with mononucleosis at 15, doctor after doctor suggested the problem was in her head. On the day Etheridge diagnosed her with POTS, "My mom and I broke out in tears," relieved to finally know her illness had a name.
Her teachers' skepticism about her illness prompted her to put a big sticker on her binder: "You may not see it but I feel it," it read. She soon could attend only two classes each day.
"I lost all my friends," she says. "They couldn't understand and I don't think they wanted to."
Her graduation last spring from Jordan High School was "my biggest accomplishment in life," she says. She's now planning to attend Salt Lake Community College part-time next year.
Her Festival of Trees contribution stems from her desire to help others, says her mother, Julie Slack. "She doesn't want to be defined by her illness, but wants to make a difference."
Without Slack and her mother, the Heidelbergers "would be lost," says Emma's mother, Marcy Heidelberger.
They connected even before Emma was formally diagnosed and now the girls, though seven years apart, are close. Each has insomnia and they will text in the night, helping each other feel less alone.
Once a week, they go to physical therapy together.
Emma has stopped going to sixth grade at Indian Hills Middle School in Sandy; now a teacher comes to her home once a week to check her school work.
And she had to drop out of dance, including a part as an Arabian dancer in Mountain West Ballet's performances of The Nutcracker.
"Dance was her life," says her mother. "Now it's POTS."
Meeting Emma has been a big bonus of decorating a festival tree, says Slack. "She is the little sister I never had."
Emma, who has two younger sisters, knows how she feels. "She's the big sister I never got to have."
If you go
The Festival of Trees, now in its 43rd year, raised $1.8 million last year for Primary Children's Hospital.
Some 800 trees, as well as wreaths and quilts, will be on display at the South Towne Exposition Center, 9575 S. State St. in Sandy, from 10 a.m. to 10 p.m. Wednesday through Saturday.
Tickets are $5 for adults, $4 for seniors and $3 for children ages 2 to 11. Six immediate family members can enter for $15 on Wednesday and discount tickets are available at most Zions Bank branches.