STORY / PUBLIC SOURCE RECORD
How Bjørn Angelsen’s innovation spearheaded a medical ultrasound industry
- Published 8 March 2023; updated 21 September 2026; estimated reading time 5 minutes. The article traces medical Doppler ultrasound in Norway to early-1970s collaboration in Trondheim among physician Alf Brubakk, engineering student Rune Aaslid and engineer/professor Bjørn Angelsen. Aaslid and Brubakk made “Jenny,” an analogue-electronics cardiovascular simulator; their need for experimental flow data led Angelsen to create the Pulsed Echo Doppler Flowmeter (PEDOF), which measured blood velocity in the aorta and heart using the Doppler effect.
- Cardiologist Jarle Holen and Aaslid applied Bernoulli’s principle to estimate pressure gradients across narrowed heart valves from PEDOF flow readings, allowing cardiac pressures to be assessed non-invasively. Angelsen improved Doppler sensitivity and developed pulsed-wave and continuous-wave approaches for spatial resolution and high-velocity measurements. His simplified relation, P = 4V², is described as a widely adopted clinical formula nicknamed the “E = mc² of cardiology.”
- In summer 1976, Angelsen hired five NTNU engineering students to assemble ten Doppler units; four were sold. Although early units lacked imaging and were difficult to use, Liv Hatle used one to develop cardiac diagnostics and Sturla Eik-Nes used another to study foetal blood flow. The group later partnered with Horten startup Vingmed to add imaging and commercialise the technology. Their CFM 700, described as the first annular-array colour-flow imaging system, was introduced at the American College of Cardiology meeting in Atlanta in March 1986 and ultimately sold 4,500 units.
- Alumni of the prototype team later included Kjell Kristoffersen (GE Ultrasound technology lead), Arne Grip (founder of Medistim), Sverre Horntvedt (CEO of Sensonor) and Veroslav Sedlak (business development at Goodtech). The article says GE Healthcare incorporated the research into its ultrasound business, citing USD 3 billion annual revenue from a 2019 investor-day source. Angelsen founded SURF Technology in 2010 as an NTNU spin-off.
- Written by Leah Anderson for EXACT-Therapeutics, Innovation Norway, Norway Health Tech and Investinor, as part of “The global reach of Norwegian ultrasound innovation.” Contact for story submissions: Masha Strømme, Masha@exact-tx.com. References listed include Aaslid’s 1974 thesis; Aaslid/Brubakk’s 1973 paper and “Jenny” history; Holen et al.’s 1976 study; an EFSUMB history by Knut Matre; and GE Healthcare’s 2019 investor statistics. Related industry: Health and life science.