Volkert Zeijlemaker received a bachelor degree in microwave technology in 1977 and an MSc degree in micro-electronics from the University of Twente in 1980. From 1980 to 2014 he worked at Medtronic Bakken Research Center, in Maastricht, the Netherlands. There, he was involved in the development of new pacemaker concepts to treat arrhythmia (fast heart rhythms) using shocks. The work resulted in the first commercial implantable defibrillator in 1990, an important step to treat sudden cardiac arrest. In 1992 he switched to clinical feasibility studies to prove new anti-arrhythmia pacing concept in patients, using an external cardiac stimulator controlled by a laptop. From 2000 onwards he was involved in the process to make the pacemakers MRI safe. He retired in 2014.