A device designed to close a common heart defect was implanted for the first time in humans Tuesday in several heart patients in Frankfurt, Germany.

The surgeries mark the launch of a European clinical study of the device, called the Coherex FlatStent PFO Closure System, the brainchild of Salt Lake-based Coherex Medical Inc. If all goes well, the device then will begin the long FDA approval process in the United States as well, according to CEO and president Richard Linder. But first, the company plans to complete a global randomized trial to see its impact on closing the heart defect, called Patent Foramen Ovale, or PFO.

Like fingerprints and snowflakes, each PFO heart defect is unique. And they are so common it is estimated that one-fourth of all mammals — people, pandas and pigs — have one.

PFOs have been linked to strokes and to migraine headaches. The foramen ovale is a tunnel-like opening between a fetus' upper heart chambers that lets blood bypass the lungs, a good thing in the womb but not after birth, when it's supposed to close. Those that don't are called "patent."

Because a PFO lets blood skip the lungs and shunt directly from the right side of the heart to the left, clots formed in the body can get into the arteries that feed the brain and result in a cryptogenic stroke.

A half-million cryptogenic strokes worldwide every year are directly attributed to PFOs. Even more often, researchers believe, PFOs are directly responsible for some migraine headaches, although the "how" and "how many" are unknown.

The typical method to try to repair a PFO is similar to that used for atrial septal defects. A disk is placed on each side of the defect and clamped together to form a solid wall. But it doesn't work particularly well with PFOs because the lengths, widths and dimensions of the defect are always different.

Various companies have tried different things, from one that focuses on sutures to a variety of implantable devices, but it hasn't been easy, Linder said. The FlatStent implanted this week is Coherex's third-generation device, although it's the first one the company has tried in humans. It was determined to devise something interventional cardiologists could use and tried a couple of different approaches, including radio-frequency-based technology. When that didn't work, the company opted to try something new.

The Coherex device is small and looks delicate, although it's not. One of its unique features is that it's deployed inside the tunnel of the PFO, so it closes the defect from within.