A Connecticut man shared his story of survival after a seizure and cardiac arrest in the middle of an international scuba diving trip.

This avid athlete (diver, spartan racer, triathlete) Paul Shelley of Newtown, had an undetected cardiac condition called a patent foramen ovale (PFO) — a hole between his heart chambers that could have turned deadly. He wants others to know, especially those who are in excellent shape, that some warning signs of this heart condition are easy to dismiss — and he’s sharing his story, hoping it can save someone’s life and prevent a cardiac emergency.

PFOs have gained recent publicity after celebrities such as Hailey Bieber announced having this condition — 25 to 30 percent of the general population has PFOs and doesn’t even know it. Doctors want the public to know about the possible dangers and to not ignore possible PFO warning signs that often go undetected and ignored. Being aware of symptoms (such as shortness of breath — as this patient experienced) can save someone’s life.

Shelley, a husband, and father of two in his early 50s, was on a diving trip to see whale sharks in Belize in June. He did several dives and snorkeling in one day — and an hour later his situation turned dire. After resting on the boat, Shelley unexpectedly collapsed.

Shelley said it was fortunate that weather forced his boat to cancel the second half of its diving tour — he could have been further out to sea when he began to have medical difficulties, instead of on his way back to shore.

He was medevaced to a hospital, and while on the plane, he had a second medical emergency — his lips turned blue and he slumped in his seat, unresponsive to attempts to wake him. Fortunately, a doctor had come on the plane with him, and gave him an adrenal shot.

“He said, ‘don’t do that again,’” said Shelley, noting that the doctor had only one epipen.

At the hospital, Shelley spent five hours in a decompression chamber. Shelley had the bends — small air bubbles in his blood caused by decompression when surfacing from deep water. But at that point, the PFO was still undiagnosed. The next morning, Shelley spent two more hours in a decompression center, and then spent the rest of his vacation under strict rules for no drinking, no spicy foods, and no exercise, “everything you’d want to do while on holiday,” said Shelley.

Eleven days later while back in Newtown, Shelley again felt dizzy and woozy, and was sent to Danbury Hospital’s emergency room.

“All the tests showed I was in good health,” said Shelley.

Shelley was discharged, but the next morning he again felt dizzy and went back to the hospital.

They ran tests, including a cardio ultrasound and a bubble test, and put a tube down his esophagus — and found the PFO. He was recommended to a doctor at Mt Sinai Hospital, Dr Sahil Khera, who noted that this particular PFO was “especially flappy,” according to Shelley.

“It was flapping like wild, which would explain what happened,” said Shelley. “It caused my embolism on the boat.”

While Shelley said that he has had the PFO his whole life, he suspects that it “became flappy” following a dive two years ago when he was given a faulty air tank.

Khera performed surgery in September, and Shelley “felt better almost immediately.” Just this month, he was cleared to run again and he plans to resume his diving excursions in another few months once it’s safe to do so.

“I’m back to normal, and can do all the things I would normally do,” said Shelley.

Looking back on his health, Shelley said he now realizes he felt out of breath while running for the last year and a half, following a diving trip. He thought he was out of shape, but this was actually a symptom of PFO. He wants others to learn from his experience — and if you feel out of breath, see a doctor and be diligent about getting answers. Ignoring this simple symptom could have led to him losing his life.

Editor Jim Taylor can be reached at jim@thebee.com.