I am looking for real-life high definition recordings of human heartbeat both fast (100-120BPM) and normal/slow (60BPM). I am aware that there is a happy abundance of royalty-free synthetic sounds and sound effects created to imitate heartbeat, and I am not interested in those. I am looking specifically for real-life recordings. Something that could be used to train cardiologists, say.
No need for those recordings to be long, something like 10 seconds would be enough, but longer recordings would be prefereable. Both mono and stereo tracks are fine.
I appreciate any and all help, and I will, of course credit appropriatelyany sources proposed if I use them.