When young people have a stroke, a small hole in the heart is a likely culprit.
The hole is known as a patent foramen ovale, or PFO.
It should close at birth, but, when it doesn't, a blood clot can pass from one side of the heart to the other and travel to the brain, where it causes a stroke, said doctors who are not involved in treating Penguins defenseman Kris Letang.
Simple actions -- coughing, sneezing or weightlifting, for example -- can be contributing factors.
The team said Friday that Letang, 26, had a stroke that could be related to a hole in the wall of his heart, but didn't provide other details. Jennifer Frontera, a neurologist at Cleveland Clinic who is board-certified in stroke and neurocritical care, said PFOs are one of the more common causes of stroke in young people.
About 25 percent of people have PFOs, but most never have a problem with them, Frontera said. Aspirin and blood thinners are the most common treatments for those who do, she said, adding that procedures for closing the hole are under study.
"The data have been real mixed on those," Frontera said.
During fetal development, when the lungs aren't used, the hole helps circulate oxygen-rich blood provided by the mother, said Kevin Cockroft, a neurosurgeon and co-director of the Penn State Hershey Stroke Center. After birth, Cockroft said, the hole isn't needed because the lungs oxygenate blood they receive from the right side of the heart and send back out through the left side.
If a change in blood pressure allows a flap over the hole to open, he said, a blot clot can pass from the right side of the heart to the left. It then can travel to the brain and cause a stroke -- an arterial blockage that is most often associated not with young athletes but elderly people and those with diabetes, high blood pressure and other chronic diseases.
Sneezing, coughing and bowel movements all can cause the flap to open, said May Kim-Tenser, a neurologist and assistant professor at the University of Southern California's Keck School of Medicine. Frontera said the "bearing down" action associated with weightlifting also can be a contributing factor.
Letang is known for his strenuous workouts, which include weightlifting.
Ordinarily, blood clots are caught in the lungs, said G. Alan Yeasted, chief medical officer at St. Clair Hospital.
"It just can't get through," he said.
There is some thought that some clots might form at the edge of PFOs, which commonly are a few millimeters in diameter, he said.
Cockroft said the warning signs for stroke -- such as facial asymmetry, arm weakness or speech irregularity -- are the same regardless of the victim's age. Too often, he said, they're ignored.
"That's particularly true in young people," he said.
Frontera said a propensity for blood clots and certain other conditions might increase the risk of stroke for patients with PFOs. While complicated migraines increase the risk of stroke, she said, migraines of all kinds are associated with PFOs.
Kim-Tenser said a number of tests must be performed to diagnose a PFO-related stroke. Some athletes, she said, have strokes from trauma-induced tears to arteries.
Joe Smydo: email@example.com and 412-263-1548.