The medical community has long since moved on from the cardiovascular definition of death.

UpToDate.com is about the only source I can be bothered mustering up for an internet disagreement at this time of night:

Death is an irreversible, biologic event that consists of permanent cessation of the critical functions of the organism as a whole [1]. This concept allows for survival of tissues in isolation, but it requires the loss of integrated function of various organ systems. Death of the brain therefore qualifies as death, as the brain is essential for integrating critical functions of the body. The equivalence of brain death with death is largely, although not universally, accepted [2,3]. Brain death implies the permanent absence of cerebral and brainstem functions.

Also this video seems to explain what I'm trying to say, although I'm not going to watch the whole thing at this hour and I only skimmed through it: https://m.youtube.com/watch?v=5IhxRSaJ74E