Rick and Charity Arnold, who live in Apple Valley, learned during a check-up on Valentine's Day that their smiling and always happy Paisley Mae had a heart condition.
They later learned her situation was grave - the then-4-month-old had been born without a left coronary artery.
Paisley turned 5 months old on Sunday. Her family celebrated the milestone at Loma Linda University Children's Hospital - nearly a week after the baby girl was placed on a Berlin Heart, an external device that helps pump blood through the infant's body.
Paisley was placed on the Berlin Heart on Feb. 25 as a way to help give her more time for a suitable donor to be found, said Darrell Feuerhahn, a friend of the family and a fellow firefighter with Rick Arnold.
Arnold and Feuerhahn work for the San Bernardino County Fire Department out of Hesperia.
"Overall, the surgery went pretty smoothly," Arnold said Sunday, "however, there were a couple of complications unrelated to the Berlin Heart that she since has gotten through."
There are always complications when a child as young as Paisley undergoes surgery, said Feuerhahn, but everyone is encouraged by her progress.
"The doctors are very encouraged with how far she's come all this past week," said the hopeful and tired father.
Those who know the Arnolds and little Paisley Mae feel in their hearts the tiny tot will pull through.
"Paisley is a fighter," said Feuerhahn. "This is tough for Rick and Charity to go through, but I know Paisley will come through with flying colors."
On Sunday, Paisley was dealing with an infection and other complications that will not allow doctors to remove her from a ventilator just yet, Feuerhahn said, but he noted the swelling associated with the surgery had subsided.
The Arnolds have received a huge outpouring of support since they decided to share their story.
As of Sunday, Paisley's Facebook page had more than 4,000 followers and, through the donation site, more than three times the original goal amount of $4,000 was raised.
When High Desert business owners learned of Paisley, many stepped forward and offered to help anyway they could.
One woman, who crochets one-of-a-kind hats, created a Paisley Hat, which has a big, red heart on the side. All the proceeds from sales will be going to the Arnolds.
Another woman who has an online store through Etsy.com, called Our Amy's Attic, held an auction Saturday for the family. The amount raised was not available.
The owners of La Casita Mexican restaurant in Hesperia were so moved by Paisley's story, said Feuerhahn, they offered to hold a fundraiser on March 11. All the proceeds from that night's dinner service will benefit Paisley and her family.
"We ask that everyone continue to pray," Arnold said, "continue to keep us in their thoughts, and again we're very thankful for all the hope and support everyone's shown us."
Reach Beatriz via email, call her at 909-386-3921, or find her on Twitter @IEBeatriz.