Walter Mercado, a native of the Philippines, remembers the day doctors told him that a heart defect could claim his infant son’s life before his first birthday.

Francis Steven was only 3 days old, but a hole in his heart was restricting blood flow to his lungs, causing his skin to turn blue and his body to be listless. Surgery would correct the problem, but at a steep cost: nearly 800,000 pesos, or $17,000 in U.S. dollars.

Desolate, the family began searching online for a solution.

They found one in the Heart Gift Foundation, a U.S. nonprofit that agreed to pay for Francis’ surgery at Children’s Hospital in New Orleans.

These days, the only signs of Francis’ life-or-death ordeal are the stitches on his chest, which the smiling, constantly squirming 8-month-old barely notices.

Walter does: He calls it the mark of a champion.

Heart Gift’s Louisiana chapter is one of more than 700 organizations that will be vying on Tuesday for donations as part of Give NOLA Day, a 24-hour online fundraising affair sponsored by the Greater New Orleans Foundation.

During the midnight-to-midnight event, donors may contribute no less than $10 to the nonprofit of their choice. Each nonprofit also receives a share from a “lagniappe fund” provided by the foundation, based on that nonprofit’s percentage of the total dollars raised.

Nonprofits received more than 34,000 donations totaling about $4 million on Give NOLA Day last year, $1 million above the foundation’s expectations, spokeswoman Blathrae Gillin said. This year’s goal is $4.5 million, and about $327,000 is available through the lagniappe fund.

Those interested can track organizations’ fundraising progress on an online “leaderboard,” a list of top organizations and donations that is updated throughout the day.

The organizations that netted the most money last year were the Ogden Museum of Southern Art and the Jewish Federation of Greater New Orleans, while Team Gleason and Healing Hearts for Community Development had the most individual donors.

Heart Gift didn’t do so badly, either, finishing in the top five for small organizations and walking away with $41,000. Leaders are hoping to raise even more this year, with help from New Orleans-based ED&F Man Liquid Products and Sunrise Exploration, which have pledged to match the first $12,500 and $5,000 in donations, respectively.

The organization relies entirely on private donations to pay for operations for children up to age 14 who live in areas of the world where access to such care is limited. Though doctors at Children’s Hospital donate their time, the total cost for surgery, travel and other expenses is about $25,000 per child, said Stephanie Berault, the Louisiana office’s executive director.

“Sometimes it takes them so long to find us that we’ve got kids coming here with a defect at 6 or 7 years old that we would have caught within their first year of life in the U.S.,” Berault said.

Also key to making the surgeries possible are the locals who agree to house the children and their parents while the kids recover from the operations. The families sometimes house their guests for several weeks before they are cleared to return home.

It’s been a gratifying experience for Antonio and Amy Barrios, who hosted Walter and his wife Ruby for nearly two months. The Mercados are the second family the couple has hosted through Heart Gift, which Amy signed up for after she read about the program in a magazine.

While in New Orleans, Walter tasted spicy crawfish and Popeyes chicken, and his hosts tried pancit, a popular Filipino noodle dish. They embraced each other’s differences but were surprised at how similar their lives are, Amy Barrios said.

“Walter and Ruby will be part of our family forever,” she said.

Last week, Walter and Francis returned home to rejoin Ruby and the couple’s other two children.

In an interview, Walter was in tears as he thanked Heart Gift, Children’s Hospital and the Barrios family.

“It’s really helped. It’s an answered prayer for us, especially to our son, because we know that he will be with us for a long time,” he said.

To contribute to Heart Gift or any other nonprofit, visit https://givenola.org/. Follow Jessica Williams on Twitter, @jwilliamsNOLA.