Like most physicians, Bolli was taught that heart cells don't regenerate, and that any cells which die from loss of oxygen during a heart attack are lost forever.

CNN: It's amazing what the human heart can do

Roughly 25, 000 Americans are stuck in a vegetative state as a result of suffering brain damage from a car accident or other trauma, or after their brain has been deprived of oxygen following a stroke or heart attack.

FORBES: Twilight Zone

Should the worst happen and the pope come under attack, his compartment has its own oxygen supply.

CNN: Holy rollers: Popemobiles from trucks to limos