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Atrial Flutter With Variable Conduction

Dawn's picture
Sun, 06/21/2015 - 11:31 -- Dawn

This is a good example of atrial flutter with variable conduction in a 53-year-old man.  He had been treated for a fast rate, and now has a rate of approximately 90 per minute.  No other clinical information is available.  One of the good teaching points in this ECG is that some leads show P waves (or, in this case, flutter waves) better than others.  The diagnosis of atrial flutter can be missed by practitioners utilizing only one or two leads.

The typical flutter waves, at a rate close to 300 / min., can best be seen in Leads II, III, aVF, aVL, V1, and V3.   Leads II and aVF are especially good for teaching students to "march out" the flutter waves through the entire strip.  They can be seen in the QRS complexes and T waves in these leads.

Because atrial flutter often accompanies a diagnosis of congestive heart failure, this is a good ECG for teaching the contribution of rate - atrial and ventricular - in the workload and cardiac output of the patient.

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Comments's picture
     Interesting tracing by Dawn — which shows an irregularly irregular rhythm that is not AFib (Atrial Fibrillation). Looking closer — the QRS complex in this tracing is clearly narrow. There IS atrial activity. This is best seen in the inferior leads and in lead V1 — though it is also seen in other leads. The question arises as to whether the atrial activity we see is “organized enough” to constitute AFlutter (Atrial Flutter)?
  • In this case — I believe atrial activity IS regular enough (there is no more than very minimal P-P variation, seen for some cycles in V1) — at a typical enough rate close to 300/minute (~280/minute in this tracing) — that I’d diagnose this exactly as Dawn did = AFlutter with a Variable Ventricular Response.
  • Distinction between AFib vs AFlutter is not always clear-cut when the ventricular response is not regular. At times, AFib may “organize” (at least partially, usually within the right atrium) — such that waveforms resembling flutter are seen in lead V1, but not in other leads. Although superficially regular and sawtooth in pattern — such waveforms on closer inspection are not regular. Such rhythms are sometimes designated as, “AFib-Flutter” as a descriptive term to indicate that while the rhythm looks a lot like AFlutter on ECG — it “behaves” clinically as Fib.
  • Clinically, distinction between AFib vs AFlutter is important for several reasons. While both AFib and AFlutter are increasingly susceptible to ablation as an effective treatment modality — AFlutter clearly responds better than AFib to ablation. Similar medications are used for both rhythms for initial treatment — but it may be more difficult to control the ventricular response to AFlutter than to AFib. Longterm anticoagulation is advised for both rhythms — but the risk of thromboemblism appears to be much greater for chronic AFib, given the much more disorganized nature of that rhythm.
  • The most common ventricular response to untreated AFlutter is 2:1 AV conduction. At the typical AFlutter rate of ~300/minute — this results in a regular ventricular response that is often quite close to 150/minute. 4:1 AV conduction is the next-most-common ventricular response to AFlutter. 
  • Variable conduction ratios (usually alternating at fixed intervals, such as 2:1; 3:2, etc.) are not uncommon with AFlutter. This is thought to be due to Wenckebach conduction of flutter impulses out of two or more levels within the AV node.
  • Odd conduction ratios (1:1; 3:1, etc.) are rare with AFlutter (especially if the patient is not on medication and does not have WPW). 
  • On occasion — AFlutter may conduct with a truly variable ventricular response. Whether this is the result of multiple variable Wenckebach conduction ratios out of different AV nodal levels, or simply random conduction (from concealed conduction) of flutter impulses through the AV node is uncertain. 

In Summary — I favor designation of the rhythm seen here as, AFlutter with a controlled but Variable Ventricular Response.


Ken Grauer, MD   [email protected] 

Interesting topic and comment, as usual!

Do you suggest to mention the type of atrial flutter (typical vs atipical) when interpreting a given ECG?

Mario Parrinello

Dawn's picture
Submitted by Dawn on

Hi, Mario,

We apologize that we just now became aware of your question - somehow the notification process on our website broke down.

The answer to your question depends upon your role and your goals.  If you are a cardiologist teaching a group of medical students, you would want to mention whether you feel the atrial flutter is typical or atypical.  If you are a paramedic reporting the rhythm to the ER physician, it is probably not at all necessary.


Dawn Altman, Admin

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