Innovation, influence and business in America's medical cities.

MINNEAPOLIS, Minn. — Marie Johnson helped create 2009′s top innovation and she didn’t even know it.

The director of the University of Minnesota’s Medical Device Center Fellows program developed algorithms and signal processing techniques used in detecting and analyzing abnormal heart beats. The resulting system, a juiced-up stethoscope made by Maplewood-based 3M Cos. and data-crunching software created by Zargis Medical Corp., was named Innovation of the Year by Popular Science magazine.

Johnson, who wasn’t aware of the honor until a family member called her, doesn’t get any credit from the magazine. But she says her post-doctoral work at 3M Littman Stethoscopes was crucial to the system. As proof, Johnson excitedly points to the large poster hanging outside her office in the university’s Medical Devices Center that summarizes her research.

Since the 19th century, doctors have relied on the stethoscope to listen to patients’ heart beats, relying on their own imperfect ears and subjective judgment to smoke out weird heart beats that could indicate a more serious problem: Leaky valves that restrict blood flow or structural defects like holes and tears.

The 3M Littmann Electronic Stethoscope 3200 amps up the sound of heart beats and transmits the data via Bluetooth to a desktop computer that uses advance software to analyze the signals.

“Early tests of the system suggest that it could eliminate more than 8 million unnecessary echocardiograms and cardiologist visits a year, saving some $9.4 billion and, even better, catch more of the dangerous murmurs,” the magazine said. “For doctors, and anyone with a heart, this stethoscope’s upgrades are well worth the two-century-long wait.”

Pretty impressive but let’s hope Johnson gets a bit more kudos for her current project: An egg-shaped diagnostic device that spots artery blockage by detecting and analyzing sound waves emanating from the heart. AUM Cardiovascular, which raised $1 million from angel investors, was recently named one of top three new companies by LifeScience Alley, an industry trade group.