The first anatomic description of patent foramen ovale was made by Leonardo da Vinci. He described it as a perforating channel from the left to the right chamber. Julius Friedrich Cohnheim first described the association between patent foramen ovale and stroke.

• In 1513, Leonardo da Vinci made the first anatomic description of patent foramen ovale. He wrote this in his notes: “I found from the left chamber to the right chamber a perforating channel, which I note here to see whether this occurs in other auricle (atria) of other hearts”.^[1]
• In 1564, the presence of foramen ovale at birth was first described by an Italian surgeon named Leonardi Botali.^[2]
• In 1877, Julius Friedrich Cohnheim, a German pathologist, first described the association between patent foramen ovale and stroke. This was based on a report he made from an autopsy he performed on a 35-year old woman who had a fatal stroke. He found a long thrombus in the lower extremity and a foramen ovale. He wrote in his report “I found a very large foramen ovale through which I could pass three fingers with ease. Now I could no longer ignore the fact that a torn-off piece of thrombus arising from the V. curalis, while traveling through the heart, passed out of the right atrium into the left atrium and to the A. Foss. Sylvii.”^[3][4]