Dawn's picture
Submitted by Dawn on Mon, 03/19/2012 - 19:40

The first ECG is from an active, otherwise healthy 66-year-old man who experienced a sudden onset of symptomatic tachycardia. He presented to the Emergency Dept. feeling (understandably) very anxious, with poor perfusion to his skin, chest discomfort, and palpitations. As the ED staff prepared to electrically cardiovert him, he spontaneously converted to normal sinus rhythm at a rate of 93 / min. and a QRS duration of 90 ms.

After a normal diagnostic cardiac cath, he was sent to the EP lab and the circuit responsible for this rhythm was successfully ablated. He was discharged in good condition the next day.

This is a good ECG for all levels of students. For beginners, it shows that atrial flutter is one of the rhythms we call "SVT", and it does not always conduct in a variable rate, or a rate that allows "sawtooth" P waves to show easily. You can show them that the "sawtooth" pattern, brought about by P waves that are 250 - 350 per minute, is still there if one ignores the QRS complexes for a moment. This is a great ECG for discussions of rate and cardiac output, and making decisions regarding treatment based on the patient's hemodynamic condition. For more advanced students, this ECG can lead to a discussion of the accessory pathways and re-entrant pathways that cause rapid rhythms. For RBBB criteria, click HERE.

The second ECG shows the same patient after spontaneous conversion to sinus rhythm.  The bundle branch block has disappeared, as it was rate-dependent.

Related Terms: 
Atrial flutter
Right bundle branch block
Rate-dependent RBBB
RBBB
Bundle branch block
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Dawn's picture

Submitted by Dawn on Mon, 03/19/2012 - 19:54

This patient presented with atrial flutter 1:1, and a rate-dependent right BBB.  He spontaneously converted to NSR.

For a print-quality image, click HERE.

 

 

.NSR after conversion from atrial flutter with 1:1 conduction

Dawn Altman, Admin

ekgpress@mac.com's picture

Submitted by [email protected] on Sun, 12/02/2012 - 07:07

GREAT post by Dawn of an uncommon occurrence (flutter at 300/minute) - but one that will on occasion be seen, so good to be aware of. I know of nothing other than atrial flutter that produces a regular rhythm at 300/minute. Untreated AFlutter most often conducts at 2:1 (atria = 300/min; ventricles = 150/min). The next 2 most common conduction ratios are 4:1 and AFlutter with a variable ventricular response.

  • IF ever you see AFlutter conducting at ~300/minute - this is highly unusual and should suggest the possibility of an AP (Accessory Pathway) - since by avoiding the AV node (via the bypass pathway) - it is easier to attain rates this fast.
  • These WPW patients who show capability of conducting 1:1 with AFlutter should be referred. As per the patient in Dawn's case - ablation of the AP can essentially "cure" these patients of their arrhythmia.
  • Of interest - there is bifascicular block aberrancy during 1:1 AFlutter in this case (note the decided negativity in lead II = LAHB in addition to RBBB). In the post conversion tracing - there was incomplete RBBB (rSr' in V1; narrow s waves in I,V6) - which widened to complete RBBB during the very rapid rate.
  • Another KEY instance in which the presence of WPW can be diagnosed without seeing delta waves - is very rapid AFib. Normally the AV node does not allow AFib to conduct more than ~ 180 impulses per minute. So - IF ever you see AFib conducting at rates >220/minute - that patient almost certainly has an AP (and WPW). This is very important to recognize - because treatment with calcium blockers such as Diltiazem may speed up antegrade conduction down the AP, leading to deterioration of the rhythm (to VFib).
  • For an additional example & further discussion - GO TO: ECG Interpretation Blogspot    - and also TO this LINK.

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

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