Introduction to Cardiac Rhythm Analysis


ekg analysis illustration

This page provides an introduction to cardiac rhythm analysis with links to training materials on this website.

The EKG (ECG) Waveform

EKG waveforms are displayed on monitors or paper. These EKG tracings have important features which can be analyzed to reveal a normal or an abnormal rhythm (a dysrhythmia).

EKG can include various waveform components which are can be interpreted to understand if the EKG is a sinus rhythm or abnormal:

  • P Wave
  • PR Interval
  • PR Segment
  • QRS Complex
  • QT Interval
  • ST Segment

The P wave indicates atrial depolarization and it is normally an upward deflection in the EKG tracing. Next the QRS complex indicates ventricle repolarization. It typically starts with a negative deflection, then a large positive movement and then a negative movement, the S wave. A T wave normally follows the QRS complex. It is typically a upwards waveform, indicating repolarization of the ventricles. Intervals such as the PR interval, PR segment, QT interval and ST segment can also be analyzed to understand the heart's condition.

Training Resources

Cardiac Rhythm Analysis Training

A good starting point for learning cardiac rhythms analysis is our training module. It presents a five step analysis method for quickly learning to interpret EKG tracings.

Cardiac Rhythm Analysis »

EKG Rhythm Tests

Hundreds heart rhythms in this practice test. Test can be tailored for specific learning needs.

EKG Rhythm Tests

Cardiac Arrhythmia Information

For additional information about cardiac arrhythmia and many other EKG topics, visit

External References

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