Depolarization — ECG/EKG Terminology

Definition: The electrical activation of heart cells that triggers contraction. Depolarization is the electrical signal; contraction is the mechanical result that follows.

Key Facts

• Begins at the SA node and spreads through the heart
• Happens very quickly (milliseconds)
• Each region that depolarizes triggers the next region
• Creates the electrical current we detect on the monitor

ECG Connection: Every waveform you see on the ECG (P wave, QRS complex) represents depolarization of heart tissue.

Why It Matters: Every waveform represents depolarization; understanding this unlocks rhythm interpretation.