Lisa Radogno, a congressional staffer on Capitol Hill, was talking on the phone with a friend from her Washington, D.C., home on Tuesday when she suddenly had difficulty breathing.
The friend called 911, but when rescuers arrived, Radogno was already unconscious and not breathing.
"Just seeing that and me being just down the hall, it's very alarming," her neighbor, Nakia Leggett, told ABC's Washington affiliate WJLA. "I had no idea something like this had happened."
Radogno died of a massive pulmonary embolism, a blood clot in her lung, on Wednesday, according to a statement from her mother, Illinois State Sen. Christine Radogno. She was 31.
About a month before her death, Radogno had been crossing the street when she was struck by a car in a hit-and-run accident, according to WJLA. She injured her arm and legs, and had been recovering in her home state of Illinois before recently returning to D.C.
Serena Williams suffered a pulmonary embolism in 2011.
Watch the anatomy of a pulmonary embolism.
An extreme gamer died of a pulmonary embolism.
Blood clots tend to form in the legs after trauma and then travel up to the lungs, where they prevent blood flow said Dr. Robert Schilz, the chief of pulmonary and critical care at UH Case Medical Center in Cleveland, Ohio. But other risk factors include things like smoking, taking oral contraceptives and being obese.
"We know that damage to an arm or a leg or so forth can lead to the body's attempt to heal that," Schilz said. "Our body tries to stop the bleeding and damage. ... That can also lead to the formation of blood clots."
But it's not uncommon to have a pulmonary embolism long after trauma, said Dr. Rashid Ahmad, a cardiac surgeon at Vanderbilt University Medical Center in Nashville, Tennessee. One of his patients was on a transatlantic flight three months before he needed medical attention.
"It can vary," Ahmad said. "It can be a week before, a month before or 3 months before."
Still, the clot could have formed during Radogno's recovery, especially if she was immobile for long stretches of time, Schilz said.
Radogno's travel history could have also played a role, too, Ahmad said. Though the hit-and-run may have been the inciting incident for her embolism, he said the clot could have grown during her immobile recovery, and trips to and from Illinois.
"So keep in mind that even if she had a small pulmonary embolism after the first one, that can then grow," Ahmad said. "These clots can be 20 centimeters long. ... When you see this, you're like, 'My god, how can that be in there?' The patient is walking around with a clot size of a thumb and 18 centimeters long inside the pulmonary artery."
In young patients like Rodogno, the heart will compensate for the clot, minimizing the effects, Ahmad said. Shortness of breath often gets ignored.
Things to look out for include unexplained pain or swelling in the legs, which can be a sign of a blood clot, Schilz said. Sharp pain in the chest or difficulty breathing are signs of a pulmonary embolism and require immediate medical attention.
Once caught, doctors may treat the clot with anticoagulants, clot-busting drugs or emergency surgery.
"The lag between symptoms and death can be very rapid sometimes," Schilz said.
Pulmonary Embolism After Hit-and-Run Kills Capitol Hill Staffer