When a teenager's heart stopped, his friends jumped into action and their CPR training saved his life.

May 10 started like any other day for Laura Machnik, who said goodbye to her son JJ, 18, before heading to work. He was supposed to work out at a friend's house that morning, and after arriving at work, Machnik confirmed he got there safely.

A few minutes later, his phone rang. It was the mother of the friend JJ was visiting and who was calling to bring him news that Machnik had been dreading for years.

At age 14, JJ was diagnosed with hypertrophic cardiomyopathy, a genetic heart disease that can cause sudden cardiac arrest. He was an active athlete and never experienced other symptoms of the disease, such as shortness of breath or chest pain. But shortly after he began training alongside friends Trevor Hodgins, 14, and Giovanni Scafidi, 18, his heart stopped.

“(She) called me and said 'You need to get to my house as quickly as possible, JJ passed out on the treadmill,'” Machnik told CBS News. “All I said was, 'Does he have a pulse?' as I was running out of work… knowing what was happening, I was like, “OK, this is for real, this is it.”

As Machnik arrived, Hodgins and Scafidi jumped into action, performing CPR and calling 911. When first responders arrived, Hodgins and Scafidi informed the paramedics of JJ's diagnosis so they could treat him immediately. His friends' quick response and quick thinking helped save JJ's life, his longtime cardiologist said.

“They gave him the best chance of surviving,” said Dr. Matthew Martinez, a sports cardiologist and hypertrophic cardiomyopathy expert at Morristown Medical Center in New Jersey. “They told me it was less than a minute before they started CPR. These are the phrases we really want to hear when we're trying to figure out how kids are going to behave after an event like this- this.”

What is hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy is a genetic heart disease that affects about 1 in 500 people, according to Martinez. The disease causes abnormal thickening of the heart muscle, making the heart ineffective at pumping blood.

There are two subgenres of the disease: obstructive and non-obstructive hypertrophic cardiomyopathy. JJ was diagnosed with non-obstructive hypertrophic cardiomyopathy, which affects approximately one-third of all patients. This version of the disease allows the left ventricle of the heart to stiffen, but does not stop blood from flowing like obstructive hypertrophic cardiomyopathy can.

Martinez said children are usually tested for the condition if a parent is known to have it — and JJ's father, Jeff, had been diagnosed with the condition a few years prior. JJ was tested at age 14 after a routine exam returned abnormal results.

Symptoms of hypertrophic cardiomyopathy include chest pain and difficulty breathing, according to the Cleveland Clinic website. Monitoring and treating the disease is largely about measuring these symptoms and their impact on the patient's life, Martinez said.

For JJ, an athlete and active teenager, this meant annual exams and careful consideration of which sports he would participate in. It also meant making sure the people around him I knew what to do if he suffered a sudden cardiac arrest.

“We would discuss how you can make sure that you and your coaches remember that low risk doesn't mean no risk,” Martinez said. “We prepared for it. We talked about it CPR with his mom and dad. We made sure the coaches and the school knew, and he went and purchased his own automated external defibrillator. »

JJ also made sure his peers and teammates knew how to perform CPR. This training helped him stay alive when he collapsed in May.

“JJ is alive because his friends acted quickly, because we were prepared for it,” Martinez said.

Treating sudden cardiac arrest

On the way to the hospital, JJ crashed twice in the ambulance and had to be resuscitated by the paramedics. Once stabilized, he was transferred to Morristown Medical Center. There he was greeted by cardiologist Dr. Amirali Masoumi and several days of intense treatment began.

The situation was “rather complicated,” Masoumi said. His heart, which normally pumps at about 70% of a standard person's functionwas only operating at about a 20% rate, Martinez said.

JJ was placed in an induced coma and his body was cooled to preserve as much brain function as possible. Over the next 24 hours, his kidney function also began to decline and his heart continued to have difficulty beating. This led Masoumi to put JJ under surveillance. ECMO, or heart-lung machine to let his organs rest. All this time, no one knew how much JJ's brain function would be affected, Masoumi said, which made care even more complicated.

“We got together, we had a very honest conversation with the family, a tough, tough conversation, telling them that if he doesn't wake up, if his brain doesn't show any signs of healing, it doesn't matter how much “We “We have the machines we have, it doesn't matter if we resuscitate the heart and lungs, unfortunately our options will be limited,” Masoumi said. Three days after her collapse, on Mother's Day, the family had a frank conversation about the possible need for a heart transplant if JJ woke up.

“JJ is an envelope pusher,” his mother said. “The night before, a heart transplant was on the table. That's how we went to bed. … Then we woke up and his heart started working. It just started working again. I said: “Could it be any other way than the JJ way, to hear the worst possible information and then say 'Oh wait, I'm just kidding, here I am?' It's our son.”

Early in the morning of May 14, there were still only limited signs of brain function, Masoumi said. But a few hours later, JJ's condition improved.

“I really didn't expect that between 6:30 in the morning and 9:00 a.m., he would pull himself together and start fighting,” Masoumi said. “It was extremely gratifying to hear that. The rest is easy, because now we are in a game that we know. We know the heart. The brain is intact. It was following commands. We knew we would have options to him. ”

On May 17, JJ celebrated her 19th birthday by walking and starting physical and occupational therapy. On May 23, he was released from the hospital, less than two weeks after his admission. Now he has an internal heart defibrillator implanted in his chest, which will hopefully prevent future sudden cardiac arrests, Martinez said.

He will continue to be monitored regularly, Martinez said. For now, athletics aren't on the agenda, but Machnik said JJ has gotten into some end-of-year activities like prom and his picnic for seniors. On June 20, he walked across the stage at his high school graduation.

Days before, he told CBS News that he was looking forward to this day and celebrating how far he had come since suffering a sudden cardiac arrest a month before.

“After what happened, which was devastating, this was the best it could be,” JJ told CBS News.