By Kay Quinn, Healthbeat Reporter
KSDK -- It was seven years ago NBC reporter David Bloom died while covering the war in Iraq.
He didn't die in an enemy attack, but of the innocent act of being cramped in a small space for too long.
Here's a look at how easy it is to develop something called deep vein thrombosis or DVT.
"About halfway up the escalator I said boy am I out of shape," said Dr. James Fleshman, a colorectal surgeon at Barnes-Jewish Hospital.
But this doctor, who runs six miles, three times a week, knew he wasn't out of shape.
What he didn't know was that his breathlessness came from blood clots in his legs, called deep vein thrombosis.
They started during an airplane ride, and traveled to his lungs, creating another condition called pulmonary embolism. Sudden death occurs when those clots prevent blood from circulating to the heart.
It's what killed Bloom in the spring of 2003. He was just 39-years-old. He had spent the previous several days in a cramped tank, his movement limited; perhaps the number one risk factor for DVT.
"I tell people who are taking a trip to, every hundred miles or so if they're in a car or automobile to get up at 100 or 150 miles and to get up and walk around," said Dr. Gregorio Sicard, a vascular surgeon at Barnes-Jewish Hospital, who treats DVT.
600,000 cases of DVT are diagnosed every year, but many more go undiagnosed. The Centers for Disease Control calls it an important and growing public health issue.
Dr. Fleshman put off getting diagnosed for two months.
"Dr. Sicard got me off an elevator and said you need to go get your ultrasound now," said Dr. Fleshman.
An ultrasound or CT scan can find them. Blood thinning drugs can make them go away and stay away. But it's still no guarantee they won't come back.
"My first DVT and pulmonary embolism was in 2005," said Dr. Fleshman. "However in the fall of 2009 I found out I had a recurrence of my DVT."
Dr. Fleshman now limits his air travel, takes blood thinning drugs and is thankful for surviving what at least 60,000 people will die of this year.
"It made me realize how valuable the time is I spend with my kids, my family," said Dr. Fleshman.
Other risks include age, obesity, recent surgery, taking certain medicines, even smoking. But Dr. Fleshman's only risk factor was his frequent air travel.