ALS algorithm

- Interpreting the ECG

A rhythm strip has already been recorded. You decide to interpret this as a guide to diagnosis and treatment:
Examine each image and select your responses. When you are ready, select confirm to receive your feedback.

Case 1

An ECG rhythm strip
  • 1. Is there any electrical activity?

Case 2

An ECG rhythm strip.
  • 2. Is the ventricular (QRS) rate normal?
  • 3. Is the QRS rhythm regular?
  • 4. Is the QRS complex width normal?

Case 3

An ECG rhythm strip.
  • 5. Is atrial activity present?
  • 6. Is atrial activity related to ventricular activity?

References

Chapter 8 of the Advanced Life Support (ALS) manual has further explanation and examples of how to analyse cardiac rhythm from the ECG.

Essentials: Components of a normal ECG rhythm strip

  • Depolarisation begins in the SA node and then spreads through the atrial myocardium
  • This depolarisation is recorded on the rhythm strip as the P wave. The heart responds to this electrical stimulus byatrial contraction
  • The small isoelectric segment between the P wave and QRS complex represents the delay in transmission through the AV node
  • Depolarisation of the bundle of His, bundle branches and ventricular myocardium is shown on the rhythm strip as the QRS complex
  • The T wave represents recovery of the resting potential (repolarisation) in the cells of the conducting system and ventricular myocardium

<p>Components of a normal ECG – close up of a rhythm strip.</p><p></p>

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