They had one of these ages ago at the Rutgers College Agricultural Research Station when I was a kid.*
*We called it The Piggy Farm.
And also a temporary one. I think that were we to try and maintain an externally removable plug to the heart, the nurses would be placing bets on which would kill the patient first: infection or a clot.
Holes/plugs in stomachs and intestines are possible because those are parts of the body with immune defenses against pathogens. They’re “used to” germs getting in there, and they can fight them off very well. Holes in, say, the bladder, tend to be more troublesome, and often get infections, despite careful use of sterile technique to keep them as clean as possible. A hole through the heart with an externally accessible plug (which means we also need a hole through the skin, muscle, bone and pericardium) is putting holes in lots of body parts that are sterile by nature, and don’t deal well with bacterial invasion.
Also, clots. Clots form around stents and scar tissue and artificial valves. I shudder to think what sort of clotting could happen around an actual plug.
Smart mom, though. Also, if your kid is running around with a toothbrush and falls and impales herself through the back of the throat with the toothbrush, don’t pull it out. Get her to the ER first. Actually, pretty much any time anything larger than an *eyelash *is impaled in anyone, don’t pull it out. It can be very hard to estimate the size of what’s under the skin by what you see sticking out. And even an inch long bit of wood in a foot could be pinching off a or plugging up a torn blood vessel big enough to cause dangerous bleeding when the foreign object is removed. Best to do that in a nice clean ER room where they have sterile clamps and suture kits.