My Aunt died like that. She needed a pace maker was all but because she was on morphine and didn't "know" her kids when they came in, the kids determined she wouldn't have wanted to live like that and ordered her feeding tube removed.
My cousin had liver cancer, went to the hospital and was talking about getting her glasses fixed when she got out! Fully coherent, until the Dr told the family that she wouldn't get any better, so they told him to stop feeding her too.
It would be a rare doctor who would determine that a patient merely needed a pacemaker but would remove and kill a patient based on the wishes of the family. Why, he'd be subjected to a lawsuit and you should institute one right away.