Clinical application of cardiac catheterization began with Werner Forssmann in the 1930s, who inserted a catheter into the brachial vein of his own forearm, guided it fluoroscopically into his right atrium, and took an X-ray picture of it. Forssmann did this procedure without permission. He obtained the assistance of a nurse by deceiving her that she was to be the subject of the experiment. He tied down her arms while inserting the catheter into his own arm, only releasing her at the point it was too late to change, and he needed her assistance. Forssmann was twice fired for carrying out these self-experiments, but shared the Nobel Prize in Physiology or Medicine in 1956 for this achievement. Cardiac catheterization is now a routine procedure in heart surgery.