A vacuum cleaner for your brain? That's the innovation at Penumbra, a medical-device company that makes equipment to treat strokes and brain aneurysms. CEO Adam Elsesser co-founded the Alameda, California-based business in 2004 with his best friend from college, Arani Bose, a doctor and Penumbra's chief innovator and director. In September, the co-founders took Penumbra public, demonstrating that even in choppy markets, entrepreneurs who find scientific innovations can reap big rewards. 

-- As told to Victoria Finkle

We wanted to start a business that created products that would have a huge impact on patients and their families. Initially, we focused Penumbra on ischemic stroke. That's when there's a blood clot that gets lodged in an artery in your brain. The goal is to get the clot out as fast as possible. We developed a device to do that, with a treatment known as mechanical thrombectomy. We designed a special type of catheter for the brain. The device is like a vacuum cleaner--physicians use it to suck the clot out directly from the artery.

33 MillionThe number of strokes, of all kinds, suffered worldwide in 2010, according to the American Heart Association

Then we started looking at other areas within the neurovascular world, searching for ways to treat brain aneurysms and what's called the peripheral vasculature, which is the arteries and veins outside of the heart and the brain. We have a product that uses aspiration, or suction, to remove blood clots there. These clots can be limb- and life-threatening, and traditional treatment typically involves administering drugs to slowly dissolve them. That can take days, and may result in costly ICU stays.

In the beginning of 2015, there were some watershed trials published in The New England Journal of Medicine that showed that mechanical throm­bectomy provided patients with superior outcomes compared with drug treatment alone, which at the time was the standard of care. As a result, there is a transformation under way in treating the millions of people around the world who suffer strokes each year. When we went public in September, we had a stroke patient who had been treated with our device ring the bell on the floor of the New York Stock Exchange.

We didn't go public that early. And we did that very much on purpose, to ensure that the foundation that we had built at the company, not just financially, but culturally, was very strong. Medical issues aren't going away, and health care globally is not going away. The question is, what are we doing medically? And are the tools and devices we're working on not only helpful clinically--do they make patients better--but do they also help reduce the costs to the overall system?