There are tricky areas at the juncture of law, medicine and real world practice, but this doesn’t seem all that murky to me.
An “intern” doesn’t get to make that kind of choices about the course of medical care. It is not their degree that enables them to practice medicine legally, it’s the license (e.g. a license to practice medicine or surgery may be granted in the US for holders of non-doctorate foreign degrees we don’t grant in the US, such as the MBBS) Interns only practice under a “limited license” issued under the aegis of a teaching hospital, and only valid while they are under supervision. They don’t have a “real” license of their own, and can’t so much as write a prescription for shoe inserts outside of their hospital duties without breaking the law.
No hospital would sanction this “trick”. Medical risks aside, it would be a huge black mark that could (in theory) could get the program booted from a local or national donor organ networks. Further, barring some freak failure of the "off"switch, cutting an LVAD line is not the practice of medicine. Doing it without the authorization or knowledge of the attendings is the same criminal act whether it was done by an intern or a patient’s worried (TV-watching) girlfriend.
I’d think that there’d be a fair chance that the intern could be prosecuted, if some victim, relative or other involved party pushed for criminal sanctions – and there may be many ‘victims’: the person who would otherwise would have gotten that heart, the hospital, the donor organ network… and I know plenty of attendings who would want to see such an intern burned at the stake.
While IANAL, I think quite a few felony charges could be plausibly argued, and it is my understanding that when foreseeable injury/damage occurs as a result of a neglectful or reckless act (more so, a crime), the defendant “takes the victim as they are” – i.e. You didn’t know the guy had a heart condition when held a gun to his head during a bank robbery, but even if he’d just come from a meeting where a team of docs had given him a week to live, you can’t say “he’d have died anyway”. It was his week to live, and you stole it with an act you had no right to commit.
There’s a lot of “luck of the draw” in complicated medical cases. It would be pretty rare that one could say in hindsight that the patient would have died anyway if they got the next donor organ. IANA transplant surgeon, but they do disqualify patients with conditions that strongly decrease survival like severe pulmonary disease, severe osteopenic bone disease, and untreated chemical dependency – much less any “he’ll die anyway” condition like active or untreatable malignancy [cancer therapy and antirejection therapy usually work at cross purposes]
More often, if a transporter accident scattered 100 copies of the hospital patient and team across the planet, some of the identical patients would live and some wouldn’t. By changing the timing and donor organ with a criminal or reckless act outside the scope of their professional authority, the intern may have caused the patient to die when they might have lived.
(As an aside: that’s not just the limits of our knowledge, it may literally be true: chaos theory and advanced theories of heart conduction have a long history together. Two consecutive heartbeats are only superficially identical, so one copy could go into a fatal arrythmia, while another didn’t, based on the “butterfly effect” sequelae of light coming in the patient’s window at a different angle
But rather than manslaughter, I’d say that surreptitiously disconnecting the LVAD line (how did they do that without triggering the pump alarm?) makes them guilty of both malpractice and reckless endangerment even if no one were harmed in the making of this scenario, Medical mapractice is generally a civil offense, but at least some states have a “felony reckless endangerment”, and even misdemeanor reckless endangerment can carry substantial jail time.