Step 1 Rhythm Analysis ECG Interpretation #318


  • When analyzing cardiac rhythm strips it is important to recognize what the cardiac complex represents and what is considered normal versus abnormal.
  • The technique and interpretation of cardiac rhythms is a combination of science and art.
  • The more you practice rhythm analysis the more comfortable you will be with the process involved and the intuitive aspects of interpretation.


  • When a normal heart is beating this is the result of electrical impulses that spread through the atria and then the ventricles in an organized, sequential manner. Atria, then ventricles, atria, then ventricles over and over again.
  • When analyzing the tracing you will first check R wave to R wave across the strip. If the intervals vary by 1 ½ small boxes or less the rhythm is considered regular.
  • If you take your own pulse now and then again in 10 minutes it is unlikely that your heart rate will be exactly the same number. This is because of a number of factors all working together in an effort to maintain our body within a specific range of “normal”, often referred to as homeostasis.
  • R wave to R wave analysis refers to the rhythmicity of the ventricles.
  • Now measure the P wave to P wave intervals. This refers to the rhythmicity of the atria.

Practice 1

analysis ecg image 104

Analyze this tracing. Its is regular or irregular?

Regular Correct. Its is regular with constant intervals



Practice 2

analysis ecg image 105

Analyze this tracing. Its is regular or irregular?

Regular Incorrect.

Irregular Correct. It is irregular – changing intervals.

Authors and Sources

Authors and Reviewers


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