Lol, reading this just brought back soooo many memories. I was such an adventurous child so I had every possible accident as a kid; from burns to falls and electric shock.

Secondly, it reminded me of my physics days. Man! I loved physics.

My contributions:
~That pacemaker in the heart is called the SA node, it controls the heart rate and stuff.
Medically speaking, the heart can beat on it's own even outside the body. That is a function of the SA node and other conducting fibres like the AV node, Bundle of His, etc.

Source

From the image above, you can see how the SA node "innervates" the entire heart so it stands to reason that over excitation of the pacemaker makes the heart beat faster; Atrial or Ventricular fibrillations.
It could also progress to a Flutter where the heart beats faster than flapping butterfly wings.

Thanks for your post @greenrun