Nancy Hammer waited a long time for a solution to a heart problem that leaves her susceptible to strokes — but not as long as the device's makers waited to provide it.

More than a decade after Minneapolis cardiologists conceived of a way to plug up a pouch where clots form in the hearts of people with irregular heartbeats, doctors in Minnesota are finally implanting the Watchman device in patients.

And all it took was one corporate takeover, one of the longest federal approval processes in medical device history, and a prolonged debate over which patients would receive Medicare coverage for the procedure.

The payoff is reducing strokes in patients who have irregular heartbeats, known as atrial fibrillations, but who struggle with the alternative solution — taking the blood-thinner drug Warfarin to prevent clots, said Dr. Stuart Adler, a cardiac electrophysiologist at HealthEast St. Joseph's Hospital in St. Paul.

"A lot of people would go untreated … They would have no blood thinners and just hope they were not going to have a stroke," he said.

Adler implanted the Watchman as part of research to prove its safety, but Hammer's procedure this April was a first in Minnesota following its 2015 approval by the U.S. Food and Drug Administration and a Medicare coverage decision this February.

A follow-up check on May 27 found Hammer's device was working — sealing off the left atrial appendage that assists with blood flow in a healthy heart, but serves as a breeding ground for clots in so-called AFib patients.

The plug is threaded into the right side of the heart, and then pushed to the left side through an incision made in the heart wall, and finally expanded to the proper size and shape to close off the pouch.

"Imagine if you shut off access to your attic," Adler said. "The stuff in the attic is still there but it can't get out."

Only hospitals involved in initial testing, such as St. Joseph's, received permission to implant it at first. Now St. Joseph's will train others.

Skeptics retain some doubts about the Watchman, which was produced by Boston Scientific after it took over the Plymouth, Minn., company that developed it. Inconsistent clinical trial results about its comparative effectiveness in preventing strokes are what gummed up the FDA process in the first place.

All recipients will be placed on a registry to monitor their health and build proof of whether the device helps.

Adler has followed his patients who received the implant when it was experimental, and said they have stayed off Warfarin and avoided "ischemic strokes" that are caused by blood clots.

Hammer, 79, is relieved. Her stroke risks became apparent two years ago when doctors removed a thumb-sized clot from her right arm.

But the White Bear Lake woman is among a subset of AFib patients whose blood becomes too diluted by Warfarin, putting them at risk if they suffer falls or bleeding or hemorrhagic strokes caused by blood vessels rupturing.

Hammer often suffered bruising and swelling while on the drug. She waited a year for the implant. "When I was told there was a possibility I could get off the Warfarin,'' she said, "you know, I took the chance."