This paper addresses a dichotomy in the attitudes of some clinicians and bioethicists regarding whether there is a moral difference between deactivating a cardiac pacemaker in a highly dependent patient at the end of life, as opposed to standard cases of withdrawal of treatment. Although many clinicians hold that there is a difference, some bioethicists maintain that the two sorts of cases are morally equivalent. The author explores one potential morally significant point of difference between pacemakers and certain other life-sustaining (...) treatments: specifically, that the former are biofixtures, which become part of the patient in a way that the latter do not. The concept of the pacemaker as biofixture grants pacemakers a unique moral status that gives reason to treat a pacemaker the same as other parts of the patient that are necessary to sustain life. The author employs this biofixture analysis to affirm the intuition that deactivating a pacemaker in a highly dependent patient at the end of life is, in moral terms, more analogous to active euthanasia than it is to standard cases of withdrawal of treatment. The paper concludes with consideration of potential implications for further implantable medical technologies, such as ventricular assist devices and total artificial hearts. (shrink)