7. Werner Forssmann
In the late 1920’s, Dr. Werner Forssmann was medical intern obsessed with the human heart. During that time it had been considered taboo to touch a beating heart, although Forssmann believed it was the only way to advance science. One evening, he decided to insert a thin tube into a vein below his elbow and worked it into his heart. His fellow colleagues were shocked that he was walking around and able to function. This would be the beginning of the development of cardiac catheterization.
Over the course of the next 30 years, Dr. Forssmann would perform this procedure on himself nine times, even attempting to take x-rays of his own heart. He would eventually go on to win the Nobel Prize in 1956 for his work in advancing cardiac medicine.