This is fascinating and reminds me of one of my favorite medical stories.
The doctor that invented the "blood vessel path to the heart for a catheter" was German. He had the idea to try it out, grabbed a regular catheter, inserted it into a blood vessel in his own arm and pushed it in till he felt it in his heart.
He wanted evidence that he had actually done this so he walked to the X-Ray department (he worked at a hospital) and asked them to get him a chest x-ray.
The doctor that invented the "blood vessel path to the heart for a catheter" was German. He had the idea to try it out, grabbed a regular catheter, inserted it into a blood vessel in his own arm and pushed it in till he felt it in his heart.
He wanted evidence that he had actually done this so he walked to the X-Ray department (he worked at a hospital) and asked them to get him a chest x-ray.
Wild how medicine has progressed.
(This story is from The Body by Bill Bryson)