Wallsten and the Stent

His invention saves millions of lives

Do you ever watch Grey’s Anatomy or the Discovery Channel? Then you’ve probably heard about the stent, the tiny metal tube that is implanted in a few million people every year to alleviate sometimes life-threatening constrictions in above all the coronary artery. What few know is that a Chalmers graduate invented the prosthetic that revolutionised several areas of healthcare.
A few million a year? Does anyone ever thank you?

“Yes, fairly often,” says Hans Wallstén. “Just recently I got a letter from a woman in France, whose husband has had five stents put in. She expressed her sincere gratitude. That makes me very happy, it’s every inventor’s dream to get that kind of feedback.”

In the early 1980s, Wallstén was CEO of the Bonnier-owned development company Inventing. During a collaboration with the Zürich-based coronary surgeon Åke Senning, Wallstén became aware of a major problem in cardiology. Bypass surgery, which was the primary treatment for constrictions in the aortic artery, was traumatic and resource-demanding, and the world’s healthcare systems longed for alternative methods. Cardiologists thought they’d found the solution when the first balloon angioplasty of the coronary artery was done in 1977. However, it turned out that this simpler intervention led to major risks. It damaged the artery wall, leading to a risk that plaque could be released and cause an acute blockage. This meant that a bypass team had to be on standby in case the patient’s life was in danger. Another problem was that in 30–40% of cases the procedure had to be repeated because the vessel became constricted again. The problems were so serious that they inhibited development, and that was when Wallstén got the idea for the revolutionary treatment. The self-expanding metal stent is inserted using a catheter and guided to the constriction, where it expands to create a lasting support that prevents vascular blockage and recollapse. A new research company, Medinvent, spun off from Inventing to further develop the stent, and after six years’ R&D and many animal trials, the first stent implantation in a human patient was carried out in 1986. Naturally, this made medical history, but not even Hans Wallstén and his colleagues could have predicted the wide range of uses the stent would come to have in an array of treatment areas.

“The stent plays an important role in many areas of modern healthcare, not least cardiology. Opening up a blocked coronary artery and implanting a stent to keep it open is the first line of therapy when a patient is at risk of acute myocardial infarction. If it is done early enough, it can prevent or limit damage to the heart and therefore also the negative consequences of a heart attack, such as heart failure and dysrhythmia,” says Cecilia Rorsman, head of cardiology at Halland Hospital.

With about 100 patents to his name, Hans Wallstén has built up several successful companies in such widely disparate fields as the pulp and paper industry, the steel industry and medical technology. This makes him one of Sweden’s foremost inventors and entrepreneurs. Ever since he was a child, Wallstén has been inspired by Gustaf Dalén and spurred on by a constant desire to improve things.

His foray into the world of medical technology was partly coincidental. After receiving his degree in mechanics at Chalmers in 1950, Wallstén began working in the pulp and paper industry, where he advanced rapidly. For a while he was the site manager at Billingsfors Långed, a part of the Bonnier Group, and that was where he invented a new method of paper coating, which he called Billblade. Albert Bonnier Jr recognised his great potential as an innovator and invited Wallstén – then CEO of the Fengersfors paper mill – to start a new company to develop and commercialise his innovations, as Billblade became a huge export success. That company was called Inventing. After five years in Sweden, Wallstén and his wife Ingrid moved to Switzerland and started a new branch of the company, which led to several spin-offs. He still lives and works in Switzerland today.

“I’m never going to stop inventing things, it’s my greatest passion,” says the 93-year-old, whose latest patent was approved just a few years ago. Exactly what it is, he doesn’t want to say, but it’s in the field of medical technology and has the potential to become something great. “The future will tell what comes of it,” Wallstén says.

Text: Birgitta Rorsman Photo: Peter Ringström

Published: Mon 22 Jan 2018.