Electricity was discovered in the mid-1700s, and its ability
to cause muscle tissue to contract was appreciated by Galvani
in 1791.38 The experiment of Abildgard cited above was not
appreciated to have affected the heart, and therefore early
application of electricity was designed to nonspecifically
stimulate unconscious victims or verify their unconscious
state. That electric current could cause irregular quivering of
the ventricles was appreciated in 1850 but was considered
only a curiosity (Figure 5).