My Spanish is pretty bad, but I believe this is the heart of a cow. A couple of years ago they had some of these strung up at the Heart Rhythm Scientific Sessions, demonstrating how new, thin leads could get into the coronary sinus.
Of course, your ‘thin’ leads look even thinner if you demonstrate them in a cow heart. That and I think having human hearts just hanging there would have been a health hazard. Among other things.
Happy Friday everyone! Have a good weekend.