ECG Fundamentals
Master electrocardiogram interpretation
Step 1 of 5
Basic ECG Components
The ECG is a graphical representation of the heart's electrical activity. Let's explore each component systematically.
Interactive ECG Waveform
Educational ECG Components
25 mm/s, 10 mm/mV
Click on the components below to highlight them on the ECG waveform
P Wave
Represents atrial depolarization
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PR Interval
Time from start of P wave to start of QRS
QRS Complex
Represents ventricular depolarization
ST Segment
Time between ventricular depolarization and repolarization
T Wave
Represents ventricular repolarization
QT Interval
Total ventricular depolarization and repolarization time
P Wave Details
Normal Value
< 0.12 seconds, upright in leads I, II, aVF
Abnormal Findings
- Peaked: Right atrial enlargement
- Notched: Left atrial enlargement
- Absent: Atrial fibrillation
Clinical Significance
Shows atrial electrical activity and timing