From that point onward, everything had to be done in secret. Over the next few weeks, Forssmann planned the experiment down to the very last detail. With a bit of cunning, he obtained some sterile instruments, took advantage of the relative quiet of the lunch hour, and locked himself away in the hospital’s small operating room. In no time at all, he had opened the vein in his left arm in order to introduce a well-oiled ureteral catheter into his body. Once the tube was inserted into his arm, he ran to the X-ray room and used the fluoroscopic screen to check the position of the catheter, pushing it further and further until it reached the right chamber of the heart. “I asked for X-rays to be taken in order to serve as documentary evidence.”