Isaac Asimov published a small magazine in the 1980’s.
I think it was called Science Fiction Stories, and it was a monthly collection of ScFi stories from various writers, including Isaac Asimov.
One story was of a tiny robot named CORA whose only job in life was to travel the veins and arteries of her host, a man who had a cardiac condition.
The story ends with CORA working endlessly to save the mans life, but the inevitable heart attack comes and he passes away.
It was a very moving story, but somehow I lost my copy years ago, and I’ve looked long and hard to find it with no success.
Thanks for that heads up! Asimov is a fascinating writer. I read one of his Black Widowers Club collections, and couldn’t put it down. Great stuff!
Did you know Asimov was contracted to write the book to go along with Fantastic Voyage? Some author wrote a story with the germ of the idea, but never finished it. That effort was turned into a screenplay/movie, but the producers wanted an accompanying novel. Tapped Asimov for the job—what a guy!