Dawn's picture
Submitted by Dawn on Thu, 10/10/2013 - 21:02

This is a good teaching strip for showing your students how to "see" the atrial activity separately from the ventricular activity.  The P waves, also called flutter waves, march out regularly at a rate of around 300/minute, which is typical of atrial flutter.  The conduction ratio is variable, and the intervals between the conducted P waves and the QRS complexes vary, as well, reflecting changing refractoriness of the AV node.  It is easy with this strip to "march out" the flutter waves, through the QRS complexes, and to show your students how the flutter waves are either visible, or "hiding" behind a QRS complex.  We have featured several atrial flutter examples on the ECG Guru recently.  Remember, you can also obtain rhythm strips for your basic students by cropping out the rhythm strips often found at the bottom of 12-lead ECGs.

Related Terms: 
ECG Basics
Basic ECG
Atrial flutter
Atrial flutter with variable conduction
Rhythm strip
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ekgpress@mac.com's picture

Submitted by [email protected] on Sun, 10/13/2013 - 11:46

     As per Dawn - BASIC Level interpertation of this rhythm strip is AFlutter with variable conduction - atrial rate about 300/minute.

  • Note that the QRS complex is narrow - and that slight changes in QRS morphology (ie, deeper "q" waves in front of some QRS complexes) - are most likely the result of superposition of flutter waves on a part of the QRS.
  • This is NOT "3rd degree" AV block - as the ventricular response is irregularly irregular (whereas it would generally be fairly regular if there was 3rd degree AV block).
  • This is NOT "2nd degree" AV block - as the PR interval (really the flutter wave-to-QRS interval) constantly varies. That is why this is AFlutter with a variable ventricular response.

Key Clinical Concepts to Convey:

  • AFlutter with variable AV conduction is the 3rd most common ventricular response to AFlutter (next to 2:1 and then 4:1 AV conduction).
  • IF only a single rhythm strip lead is monitored - it would be easy to mistake this rhythm for AFib, given that it is irreguarly irregular (ergo the importance of always doing a 12-lead ECG when confronted with a new tachyarrhythmia in a hemodynamicaly stable patient).

More Advanced Concept - The rate is NOT 300/minute. It is a bit slower than this. Look at the spot where the R-R interval is longest (toward the end of the tracing). Estimating heart rate (either for atrial or ventricular rates) is more accurate when you look at more than a single beat R-R. Note that there are 3 flutter waves in between the 8th and 9th QRS complexes in this rhythm strip. The R-R interval for these 3 complexes is a bit over 3 large boxes. Thus, 1/3 of the actual rate is ~90/minute - which means that the flutter rate is closer to ~ 270/minute. While admittedly it does not matter much clinically whether the flutter rate is 270 vs 300/minute - being comfortable with this every-other- or every-third-beat method for estimating heart rate is INVALUABLE in certain instances of SVT or Wide Tachycardia of uncertain etiology.

Ken Grauer, MD  www.kg-ekgpress.com   [email protected] 

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