It seems like a needle piercing the skin between two ribs to a distance of at least 2-3 cm could become lodged in tissue inside and be pulled in completely when the rib cage expands on the next breath. Once the needle is inside the body, anything goes. The heart is only approximately 3-4 cm from the skin. The heart's beating could grab the needle and pull it even farther in.

A web search brings up several instances. This one [1] at least seems to somewhat confirm my intuition.

[1]: https://timesofindia.indiatimes.com/india/Docs-use-magnet-to...