Why did Tony Stark keep the electromagnet in his chest?
The ARC reactor and electromagnet chest piece are originally there to prevent pieces of shrapnel from piercing his heart. That happens because he was fixed by a Chinese/Afghan doctor who doesn't have anything else to do it properly.
However, when he got back to the US during Iron Man and Iron Man 2, why didn't he have the shrapnel removed? Why not just immediately get rid of the electromagnet and live normally?
He later decides to have the electromagnet removed (at the end of Iron Man 3), so why didn't he do it before, especially when it was killing him in Iron Man 2? What changed during Iron Man 3 that suddenly made it possible? Or what prevented him from having it removed before?
I think this is a case where we have to suspend disbelief to be entertained.
The first thing we have to suspend disbelief for is that they were able to perform surgery on Tony Stark's open chest in a cave in the middle of a desert. No sterilized room here! Not to mention the size of the hole in Stark's chest! See how Pepper Potts can put her hand in his chest? No idea how they could have rearranged his organs to make room!
Second, the arc reactor created is also capable of great magnitudes of energy to power an Iron Man suit, something that is pure science fiction. The chest piece is also essential because it keeps the shrapnel, or fragments, from killing Tony by entering his heart. The shrapnels must be of such a small size that even the cave desert surgery could not remove all of it.
So maybe we really need to believe that the shrapnel can truly not be removed, else Tony will die.
Well, with all this sci-fy and technology stuff, why not also believe that they would have the technology to fix Tony Stark all up when he is back in the US? Say some kind way to diffuse his blood or some other fantastic surgery to remove all the shrapnel. Very true. To which I would answer:
The chest piece also serves a purpose for the story and character. It's part of the drama that if our hero doesn't have it in place, he will die. It's a physical weakness. And who's to say that Tony doesn't want someone operating on him, when he's unconscious and vulnerable, who could then simply steal his arc reactor technology? In the screenshot above, Tony is having Ms. Potts change out his chest piece in his own lab, not a doctor in a hospital.
Or even he's not the type that wants to be fixed or cured. He is a genius, superhero, playboy billionaire with narcissistic tendencies. He may not be like us in thinking of simply getting it fixed.
It also adds emphasis to when Tony Stark says, "I am Iron Man".
It's important to remember that when the Iron Man comic first came into being, something like a heart transplant was not possible, even experimentally. I believe this is a nod to keeping a part of the original storyline intact, and thus our suspension of disbelief as sunpech suggests.
Actually, there was a kid in my highschool who had a similar hole in his chest - it was covered with skin and smaller, but you could tell that at least some of the bone was missing (i.e. it was squishy). In his case I'm pretty sure it was a birth defect, but it's definitely possible to survive with something like that - on the surface he looked normal, he didn't have a respirator or anything.
Such surgeries (without advanced technology and without sterilization) were done in ancient and medieval times, and *some* people did survive them. (The emphasis is on *some*, because most didn't.)
I think I've pointed out on here before, that even with the most advanced medicine in existence currently *no reputable doctor would ever attempt that surgery on Tony.* There exists no technology capable of finding the type of microscopic shrapnel that would be lodged in his thoracic region. CAT scans cannot find them because they are too small. Same goes for x-ray's. A MRI could very well find the shards, but the magnets would pull the shrapnel out, destroying most of his lungs and heart in the process. *No doctor will just open him up and go poking around for tiny shards of metal.*
It is possible that Tony himself could apply his abilities to developing such a test, but I honestly think he has other priorities. If he's not *currently* dying from them, he'd rather devote his time to more interesting pursuits.
@GabeWillard Well, in the second movie, he _was_ dying from it. (Indirectly, at least. Removing the shrapnel would have solved his problem.)
@Izkata Clearly, inventing a new element to use as a catalyst for his handheld fusion reactor was a far easier choice than inventing a non-magnetic body scan that could detect microscopic shards of metal in his chest. :P Although, honestly, I'd argue by that point Tony had more fully "become" Iron Man. Fixing his heart would mean he could lose the reactor, but I think the reactor meant more to him than just something to keep him alive.
I'm sure he could keep the reactor just fine even without bits of shrapnel in his body.