I'm a signal that travels in waves

Across the heart, my pattern engraves.

In the body's theater, a rhythmic plot

Electrical impulses, a lively lot.

Nurses watch me on a monitor's trace

Deciphering patterns with skilled grace.

From atria to ventricles, I swiftly go

A cardiac dance, a rhythmic flow

In health and illness, I take the lead

A waveform mystery for those who read.

A cipher is used to crack the code

5 letters to translate what has been showed

Code: Letters (Capital) _ _ _ _ _