Ventricular fibrillation is one type of arrhythmia that can be deadly. It occurs when the heart beats with rapid, erratic electrical impulses. This causes pumping chambers in your heart (the ventricles) to quiver uselessly instead of pumping blood.
A VOLTAGE REGULATOR regulates the charging voltage that the alternator produces, keeping it between 13.5 and 14.5 volts to protect the electrical components throughout the vehicle. There is also a system to warn the driver if something is not right with the charging system.
What you are describing is indeed a voltage regulator, not current control. This will step down a variable input voltage to a fixed output voltage. For the above IC to work it will require at least 12.5V in, which you should have at pretty much all times, even when not running, with a healthy battery.