Clinical Notes : Cardiology

ECG Basics

What do they mean?

  • P wave: the sequential activation (depolarization) of the right and left atria

  • QRS complex: right and left ventricular depolarization (normally the ventricles are activated simultaneously)

  • ST-T wave: ventricular repolarization

  • U wave: origin for this wave is not clear - but probably represents "afterdepolarizations" in the ventricles

  • PR interval: time interval from onset of atrial depolarization (P wave) to onset of ventricular depolarization (QRS complex)

  • QRS duration: duration of ventricular muscle depolarization

  • QT interval: duration of ventricular depolarization and repolarization

  • RR interval: duration of ventricular cardiac cycle (an indicator of ventricular rate)

  • PP interval: duration of atrial cycle (an indicator of atrial rate

These notes are of relevance to the following :


ECG - Hyperkalemia - 111

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