User:Bron766/ECG/Rate

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SVT Lead II.JPG
The ECG rate describes how often the heart is electrically activated, in beats per minute.

Skills:

  • Calculate the ECG rate using large squares, small squares or a longer interval.
  • Recognise an abnormal heart rate in adults.
  • Recognise an abnormal heart rate in children and infants.
  • Separately calculate the P wave rate and QRS rate and understand the clinical significance of the two rates.
  • Understand the term 'pulse deficit' and why the peripheral pulse rate may differ from the ECG rate.
  • Practise fast and accurate estimation of heart rate from the ECG.
  • Avoid the pitfalls of instantaneous vs. average heart rate calculation.
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How to use this page:

  • Explore the sections below by clicking on Process, Review, Apply or Contribute to find a variety of educational exercises. Click again to hide the same content.
  • Read the suggestions for each type of activity.
  • Choose your learning goals using the list of skills on the previous slide.
  • Make this page better by editing it or leaving comments on the talk page.

Medical disclaimer: This page is for educational and informational purposes only and may not be construed as medical advice. The information is not intended to replace medical advice offered by physicians. Please refer to the full text of the Wikiversity medical disclaimer.

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Output: (try these suggestions, or be creative!)


Exercises:

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Active learning exercise:
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Help: Learning by connectivism involves remixing information to create new connections and links. Start by choosing materials from the collection above that are most relevant to you. Keep a record of which materials you have accessed (suggested ways of doing this can be found here). Transform the information from one format to another. A traditional example of this learning exercise might be taking a lecture and processing it to make dot point notes, but also consider other formats like diagrams, mind maps, short movies and more. Revise your notes by transforming them again rather than just passively reading them. The theory is that this exercise helps you to engage elements of active learning and learning by teaching to increase the quality of your own learning while also creating something useful for others to learn with if you choose to share it.

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Active learning exercise:
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1

ECG rate can be estimated using the formula:

300 / number of large squares between two QRS complexes
60 x number of large squares between two QRS complexes
300 / number of small squares between two QRS complexes
60 x number of small squares between two QRS complexes

2

Which of the following ECG rates are likely to be in the normal range for that person?

HR 65 in a 45 year old male
HR 80 in a 26 year old female
HR 45 in an elite athlete
HR 46 in a 78 year old male with dizziness
HR 150 in a breathless 75 year old female with palpitations
HR 155 in a newborn infant
HR 68 in a 2 year old child

3

What is meant by the term pulse deficit?

There is a deficit when the ECG rate is less than the pulse rate (e.g. palpated radial pulse)
There is a deficit when the pulse rate (e.g. palpated radial pulse) is less than the ECG rate

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Active learning exercise:
Wikiman MD.png Can you apply this information to these clinical examples?

Icon Transparent Blue.png What is the approximate rate using large squares?

Case 1
E0003115 (CardioNetworks ECGpedia).jpg
Answer
There are 4 large squares between each QRS complex. Rate = 300/4. The rate is approximately 75 beats per minute.

You can also work this out by memorising the sequence 300, 150, 100, 75, 60, 50 and counting to the 4th number, which also works out at 75 beats per minute.

Case 2
Answer
There are 2 large squares between each QRS complex. Rate = 300/2. The rate is approximately 150 beats per minute.

You can also work this out by memorising the sequence 300, 150, 100, 75, 60, 50 and counting to the 2nd number, which also works out at 150 beats per minute.

Case 3
Sinus bradycardia lead2.svg
Answer
There are 6 large squares between each QRS complex. Rate = 300/6. The rate is approximately 50 beats per minute.

You can also work this out by memorising the sequence 300, 150, 100, 75, 60, 50 and counting to the 6th number, which also works out at 50 beats per minute.

Case 4
Answer
There are 8 large squares between each QRS complex. Rate = 300/8. The rate is approximately 38 beats per minute.

Icon Transparent Green.png What is the instantaneous (beat to beat) rate using small squares?

Case 1
ECGbasic.svg
Answer
There are 25 small squares between these two QRS complexes. Rate = 1500/25. The instantaneous rate is 60 beats per minute.
Case 2
Answer
There are 19 small squares between these two QRS complexes. Rate = 1500/19. The instantaneous rate is 79 beats per minute.

Icon Transparent Green.png What is the average rate using a larger interval?

Case 1
Nsr (CardioNetworks ECGpedia).jpg
Answer

This ECG is irregular. The rate will vary depending on which beats or intervals are used to calculate it.

In 6 seconds of the bottom rhythm strip recording (30 large squares), there are 7 QRS complexes. Rate=60/6 seconds x 7. The average rate is 70 beats per minute over this interval.

In 4 seconds of the lead 2 recording (20 large squares), there are 5 QRS complexes. Rate=60/4 seconds x 5. The average rate is 75 beats per minute over this interval.

Case 2
De-Afib detail (CardioNetworks ECGpedia).jpg
Answer

This ECG is irregular. The rate will vary depending on which beats or intervals are used to calculate it.

In 4 seconds of the lead V1 recording (20 large squares), there are 12 QRS complexes. Rate=60/4 seconds x 12. The average rate is 180 beats per minute over this interval.

Icon Transparent Yellow.png What is the rate? Is it normal or abnormal? (Extension: what's the diagnosis?)


Help: For each skill, here is a collection of relevant cases and clinical examples. You can practise these skills and exercises in any order, but the coloured icons (Icon Transparent Blue.pngIcon Transparent Green.pngIcon Transparent Yellow.pngNuvola filesystems services.png) should help you to find examples of a similar difficulty level. Planned future versions of this page should allow you to keep track of which exercises you have completed, for example by exporting the list to Learnist where you can mark each item as 'done'. You can also review the concepts, theory and background knowledge in the 'Review' section above.

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