A-fib, as its called, is an irregular heart beat.
Millions of Americans have it, and because it can lead to stroke, most of them have to take a blood thinner.
But getting blood to the right balance is a big challenge. Too thin and bleeding is a big risk. Too thick, and blood clots are a danger.
Doctors with Penn Medicine are now using an FDA-approved device called LARIAT to close off a pocket of the heart called the appendage.
Blood clots can form there, then move to the brain, causing a stroke.
The lariat is threaded through blood vessels from the leg up to the heart.
And like the cowboys roping cattle in the westerns, the LARIAT encircles the appendage and closes it off.
With the LARIAT in place, patients no longer have to take blood thinners.Dr. Dan McCormick has implanted the device for several months, says that's so important for his patients.
"You can't believe how happy the patients are to be off anti-coagulant drugs. the drugs change their lives. they have to get blood tests on a weekly or bi-weekly basis. they have to change their diets," he told Action News.
Dr. McCormick says most A-fib patients should qualify for LARIAT, although it's not for anyone who's had open heart surgery.