[MHGinTN]

Um, your lack of education is showing. If the brain stem is dead, the heart is not beating without external stimulation.

[Scoutmaster]

According to the University of Miami Medical School's website on brain death:

The heart has its own pacemaker independent of the brain. As long as it has oxygen, it continues to beat. The heart could actually be removed from the body, placed in saline solution, given oxygen, and still continue to beat.

This is why although the brain is dead, the heart continues to beat.

[Drew68]

Um, your lack of education is showing. If the brain stem is dead, the heart is not beating without external stimulation.

Clearly it is you who does not understand basic human anatomy and physiology. The heart does not require a brain to function, only oxygen (provided from the lungs via machine). But eventually even fresh oxygen will not be enough to keep the heart pumping --as is being currently demonstrated by Jahi's falling blood pressure.