A missed pop fly stopped a 6-year-old's heart. His mom helped restart it with CPR.

When the Barracudas baseball team found itself in need of several players, 6-year-old Oscar Stuebe was happy to fill in as a teammate with his 7-year-old brother, Connor.

The Stuebe brothers also played together on The Yankees, another team in Palm Beach County, Florida. During a recent Yankees game, they had pulled off a fun feat. Oscar caught a pop fly in right field and threw it to Connor at first base for a double play.

The day after the double play, the Barracudas played a doubleheader. During the fifth inning of the second game, Oscar stood waiting in center field. The boys' mother, Sarah, watched eagerly from the stands, snapping photos and cheering along. Their father, Riley, was in the dugout as an assistant coach.

The batter hit a pop fly. It was nothing out of the ordinary, the kind all players and parents had seen dozens of times during the season. But that day was different.

Oscar took off running, his small legs powering him across the dusty field, his mitt in the air. It looked like he caught the ball. The crowd erupted in a cheer. Then the ball dropped, Oscar bowed his head and he collapsed.

Riley thought his son had the wind knocked out of him. Once he realized there was more to it, he dropped the clipboard he was holding and ran toward his son.

Riley could tell something was seriously wrong. He screamed "Sarah!" in a shrill, panic-filled tone that prompted her to immediately call 911 and rush down from the bleachers to the field.

When Sarah reached Oscar, his limbs were stiff and his eyes had rolled into the back of his head. Sarah thought he was having a seizure, but he had no history of a seizure disorder. Then he went still. His face turned grayish and he gasped for air.

"Oscar, you're swimming, come back up for air," Riley pleaded.

More time passed in between gasps. Sarah, who is a nurse, started CPR and shouted for someone to get an AED, short for automated external defibrillator. Only, there was no AED at the facility.

Sarah knew how to deliver quality chest compressions. She went into "nurse mode," pushing hard and fast in the center of his chest. Oscar remained limp and unresponsive.

"Where's the ambulance?" Riley yelled.

Sarah's arms were tiring, her heart racing and tears welling up. The gravity of the situation struck her. She was doing something she never imagined she'd do: CPR on her own son.

Another mother – a physician's assistant – was watching her son play ball on an adjacent field and heard about what was happening. She ran to the scene and took over CPR from Sarah.

The ambulance arrived five minutes after Oscar collapsed.

First responders continued CPR and hooked him up to an AED. Oscar was in ventricular fibrillation, a life-threatening abnormal heart rhythm that happens when the heart's lower chambers (ventricles) quiver instead of contracting normally. This can prohibit the heart from pumping blood, cause a collapse, and lead to cardiac arrest. If not treated, it can be fatal within minutes.

As the ambulance sped to the hospital, Sarah and Riley sat up front. EMTs delivered a shock to Oscar's heart.

But his heart rate was a low 37 beats per minute. EMTs continued CPR and drew up a syringe of epinephrine to help correct his abnormally low rhythm.

Suddenly, his heart rate jumped to 150 beats per minute on its own.

When the ambulance arrived, Riley screamed, "Is my son alive?"

"We've got a pulse," a fireman confirmed. "But he needs help right now."

In the emergency room, Oscar had a brain scan, X-rays and an MRI. Sarah and Riley sat in a small waiting room in metal chairs surrounded by tissue boxes. They were convinced a doctor would come in and say Oscar hadn't made it. They kneeled and prayed.

A nurse approached. "He's alive and on a vent," she said. "You can see him."

The ventilator helped Oscar breathe. He was pale and sedated.

"This is a case like Damar Hamlin," Oscar's cardiologist told the Stuebes, referring to the NFL player and his sudden cardiac arrest on the football field. So rare that "it's like getting struck by lightning," he said.

The baseball had hit Oscar in the chest and threw his heart out of a normal rhythm and caused it to stop beating. Cardiac arrest caused by a blow to the chest is known as commotio cordis.

Oscar's prognosis depended on how long his brain had gone without oxygen. Yes, Sarah got to him quickly. But was it fast enough? Had her compressions helped push enough oxygenated blood to his brain and other vital organs?

The next 24 hours would be revealing.

Their priest came to the hospital to pray with them. So did Sarah's parents.

Family members held Oscar's hand. "We love you, we're here, you're safe" was the mantra they repeated to him.

Oscar coughed all night, which actually was a good sign; it meant his brain was responsive. On that Monday morning, doctors weaned him off the ventilator and he started breathing on his own.

But Oscar was agitated and talking nonsense. He thought animals were in the hospital room and asked for someone to pass him the ball. Maybe it was a side effect of the pain medication they gave him, Sarah thought. Or maybe her son had brain damage.

Sleep ended up being the best cure. Oscar hadn't slept much since Saturday night. Tuesday evening he finally fell into a long, deep sleep.

Wednesday morning, he woke up and rubbed his eyes. He looked at Sarah.

"Hi, mom," Oscar said.

Sarah turned to Riley. "He's back," she said through tears.

Oscar looked at the balloons and the other trinkets in his room that friends and family had sent. "What are these?" he asked.

"You're in the hospital," said Sarah.

"No, I'm not," he responded.

"You are, and you're safe here with me and dad."

Oscar thought he was there to have his tonsils out, a procedure the family had scheduled for a few weeks later. Sarah and Riley explained he'd had an accident on the baseball field.

For the next few days, Oscar did physical and speech therapy. Friday he was walking on his own holding hands with Sarah and Riley. Doctors discharged him.

Oscar had missed a full week of school. The following week was spring break. He and his three brothers, Connor, plus Sean, 9, and Cyril, 3, played video games on the console a local nonprofit gifted the family.

At home, Sarah thought about how easily things could've gone differently. She and Riley keep saying and thinking a particular sentiment: "We could have had one less kid at our table."

"We were so lucky," she said.

Three months later, Oscar is back to normal, tossing baseballs in the backyard with his brothers – with one small change. All of the boys now wear a shirt with built-in protection around their heart to blunt the impact of a direct hit from a ball.

"We made it a rule," Sarah said. "We told the boys, 'You're wearing the heart shirt now.'" The Stuebes approach it like a batting helmet, and they want to normalize kids wearing heart shirts as protective gear.

Every kid on Connor's baseball team now wears the shirt, especially after a 10-year-old in their county experienced commotio cordis shortly after Oscar. (The boy was revived by an AED and is OK.)

Oscar hasn't yet returned to playing on his own team. As for Sarah, she's put her career as a fertility nurse on hold. In addition to needing more time to process everything that happened, she and her family are in the early stages of starting the Oscar Strong Foundation, a nonprofit organization to increase awareness of sudden cardiac arrest during sports. They've made it their mission to talk to anyone who will listen about the importance of CPR, too.

"Call 911 and start CPR," Sarah said.

The foundation will help drive that message home. The Stuebes want to get more AEDs onto Florida sports fields and work with teams to establish emergency response plans that include heart events. An AED has been donated to the foundation for installation on the field where Oscar's event happened. The field is closed for the summer, so it'll be in place for the start of recreation league games in September.

Sarah likes to ask people to notice if the top five places they regularly visit in their community have an AED.

"In your community, they should really be as visible as an exit sign," she said. "AEDs need to be available and accessible. Time is life."

Adds Riley: "Know how and when to do CPR, and don't be afraid to use it. Hopefully you'll never have to, but if you do, you can save someone's life."

Stories From the Heart chronicles the inspiring journeys of heart disease and stroke survivors, caregivers and advocates.