Gail Roper was fearful of making a scene.

Poised on the lip of a pool after swimming laps seven years ago, the former Olympic swimmer "knew something was wrong. It was like I was having an out-of-body experience. But it was scary." She crawled out of the pool, rattled. A month later she experienced a second episode -- her doctor later said her heart was beating irregularly. He suggested a pacemaker.

"I'm an athlete," she said. "They're for sick people."

By anyone's standards, the now-80-year-old Roper, one of the world's top female swimmers, seems an unlikely heart patient. The marine biologist from Healdsburg, Calif., swims at least three days a week and recently broke nine world swimming records. But it was the tiny device, the size of two quarters smooshed together, that enabled her to continue her lifelong love affair with water.

The petite mother of seven and grandmother, resplendent in a bejeweled Christmas sweater, spoke to several hundred Medtronic Inc. employees at the company's cardiac rhythm disease management headquarters in Mounds View on Tuesday. The 15-minute talk prompted a standing ovation and a few misty eyes as she greeted representatives of the Medtronic team that made her device.

If Roper represents a remarkable chapter in Medtronic's past, patients like her also represent a valuable chapter in the company's future.

Each year, close to 1 million people worldwide are implanted with a pacemaker -- a once-groundbreaking technology that doesn't get much attention these days. Medtronic co-founder Earl Bakken invented the first battery-powered pacemaker in 1957, establishing Minnesota as ground zero for the technology and helping create the state's highly coveted med-tech industry. Today, however, the $4 billion global industry is a mature business, said Tim Nelson, an analyst at FAF Advisors in Minneapolis. "It's a segment of the business that has been growing silently, but steadily."

Demographics may work in the device's favor -- as Gail Roper's example shows.

About 65 percent of pacemaker patients are ages 50 to 79, and 30 percent are 80 or older, while fewer than 5 percent are under 30.

As the nation's baby boomers age, demand for the device will likely remain constant, said Dr. Charles Gornick, director of cardiac electrophysiology at the Minneapolis Heart Institute-Abbott Northwestern Hospital. "Boomers are much healthier than anyone anticipated they'd be. The growth in pacing parallels the aging population."

Some interesting improvements to the core technology, which paces the heart, could give this mature technology a fresh look. Medtronic is now selling a pacemaker in Europe that is compatible with magnetic resonance imaging (MRI) technology -- most patients with the device are advised against getting MRIs. The company is working on gaining U.S. approval.

In addition, Medtronic is developing a thumbnail-sized pacemaker that is attached directly to the heart in a minimally invasive procedure.

But for patients like Roper, the current technology works just fine.

"The doctor said if I didn't get a pacemaker, I'd end up at the bottom of the pool," she said.

When girls weren't to exercise

Roper's mother taught her to swim at the age of 2 in her hometown of Trenton, N.J., which hugs the swift-flowing Delaware River. Fearful that her daughter would be swept away by the river's pull, she outfitted the toddler in a green-and-yellow bathing suit and taught her the basics.

Roper made the high school swimming team at a time when girls were not encouraged to exercise.

"We were told if we swam more than a lap we would develop heart disease and our ovaries would burst, so we couldn't have children," she said. No coach would take her on (until later), so she studied swimming technique by reading books in the local library. The Delaware River became her swimming pool and she ultimately became the state's champion swimmer between 1948 and 1951.

She moved to Washington, D.C., and began training with other women on the Walter Reed Hospital team, setting records in breaststroke, individual medley and 300-yard medley relays. In 1952, she became the U.S. national champion in the 100-yard and 200-yard breaststroke and the 200-yard individual medley.

Her talent attracted national attention: A 1952 Life magazine article described her as "scrawny" in a bathing suit and "anything but athletic" in her street clothes, "wearing glasses with a pink rim and rhinestones." In the water, though, "she looked wonderful," the article gushed.

She qualified for the 1952 Olympic team and went to Helsinki, Finland, but did not make the finals. By 1953, she was considered the top female breaststroke swimmer in the world. But then, she quit swimming to become a wife and mother, and didn't exercise (beyond chasing seven children) for 20 years.

"I was a housebound housewife," she said.

At 41, she resumed her passion, competing in contests sponsored by U.S. Masters Swimming. She now holds 103 world records, and has been inducted into the International Swimming Hall of Fame. She's traveled extensively, climbed 19,340-foot Mount Kilimanjaro in Africa, and has swum across the Nile and Lake Pepin. (The latter was "a highlight of my life.")

After eight decades, she's lost none of her competitive fire, and hopes to keep swimming and breaking records until she reaches the highest age bracket in Masters swimming, 105 to 109.

"I once read that the people most successful in sports are those who hate to lose," she said.

Janet Moore • 612-673-7752