German surgeon who shared with André F. Cournand (Cournand, André F.) and Dickinson W. Richards (Richards, Dickinson Woodruff) the Nobel Prize for Physiology or Medicine in 1956. A pioneer in heart research, Forssmann contributed to the development of cardiac catheterization, a procedure in which a tube is inserted into a vein at the elbow and passed through the vein into the heart. While a surgical resident in Berlin (1929), Forssmann used himself as the first human subject, watching the progress of the catheter in a mirror held in front of a fluoroscope screen. Forssmann's daring experiment was condemned at the time as foolhardy and dangerous, and in the face of severe criticism he abandoned cardiology for urology.

Forssmann's procedure, with slight modifications, was put into practice in 1941 by Richards and Cournand, and has since become an extremely valuable tool in diagnosis and research. It has made possible, among other things, precise measurement of intracardiac pressure and blood flow, injection into the heart of drugs and of opaque material visible on X-ray photographs, and insertion of electrodes for the regulation of the heartbeat.

Forssmann graduated in medicine from the University of Berlin (1928) and then did postgraduate study in urology at Berlin and Mainz. He served as chief of surgery at the city hospital in Dresden-Friedrichstadt and in 1958 was named chief of the surgical division of the Evangelical Hospital in Düsseldorf.