In 1952, doctors at the University of Minnesota completed the first successful open-heart surgery procedure as they operated on a young girl to repair a hole in her heart.

Years later, a physician in the Twin Cities named Kurt Amplatz developed technology for treating that same pediatric heart condition, but in a much less invasive way.

Amplatz created a medical device that could be scrunched to a size small enough to fit inside a specialized medical tube called a catheter. Doctors pass this tube through a small incision in a patient's leg all the way to the heart, and then pass the plug-shaped device through the catheter to fill the hole. The invention lets doctors repair serious heart defects in children without major surgery.

Amplatz, 95, died Nov. 6. Doctors say the "occlusion" devices exemplify the pioneering role Amplatz played in developing a new approach to treating heart ailments.

"He's a major reason that Minnesota is known for innovation in treatment of structural heart disease," said Dr. John Bass, a pediatric cardiologist at the University of Minnesota. "There are so many more children now who don't have to have surgery because they have a device that can be put in through a catheter."

Kurt Anton Amplatz was born in Austria in 1924. He attended medical school in his native country but believed he would have more opportunities to innovate in the U.S. medical system, said daughter Grace Amplatz.

Amplatz joined the radiology faculty at the University of Minnesota in 1957 and stayed there until he retired in 1999. The U was pioneering treatments in open-heart surgery at the time, and Amplatz contributed in the 1960s by developing imaging technology to outline the anatomy of the heart, said Dr. David Hunter, a longtime radiologist at university who retired this summer.

As time passed, Amplatz was among a select group of doctors who developed a new field called "interventional radiology," where doctors used imaging equipment to look inside the body while simultaneously deploying medical devices through catheters to provide treatments. Amplatz's genius was in devising the tools, Hunter said, that doctors would need for these procedures.

During his time at the U, Amplatz is credited with inventing lifesaving tools and procedures ranging from catheters and guide wires to snares and dilators that are still being used around the world. After he left the U, Amplatz created a company called AGA Medical that developed the devices to repair congenital heart defects in children.

The occlusion devices repair "septal" defects, meaning holes in the heart walls that divide the heart into four chambers. Left untreated, the holes lead to blood pressure problems that prove fatal over time.

"His greatest contribution to the health of this globe was his development of a safe, easily delivered, easy to monitor, accurate and safe technology for plugging up septal defects," Hunter said. "That's where really there are probably millions of people around the globe that owe their life or well-being to Kurt's inventions."

AGA Medical was acquired in 2010 by Little Canada-based St. Jude Medical, which has since been purchased by Abbott Laboratories. Amplatz went on to start another medical device company that continues to this day.

The U's pediatric hospital was named for Amplatz from 2009 to 2014 after a $50 million gift from his daughter Caroline. The name went away after she permitted the U to offer naming rights for the hospital to another benefactor.

In addition to Caroline and Grace, survivors include two other children, Curtis and Ria (Maria); three grandchildren and longtime partner Marianne Schulze. A celebration of his life will be held next summer.