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Trick of the Trade: Speed up ECG paper rate to differentiate tachycardias

Posted Dec 11 2012 12:00am

Undifferentiated tachycardias, especially when the rate is extremely fast, make it difficult to see anything other than the QRS complexes! Is there a P or flutter wave?

Trick of the Trade:
Double the ECG paper speed to 50 mm/sec

Standard ECG machines run at 25 mm/sec. If you double the paper output speed, subtle ECG findings hidden in the tracings become more evident. Imagine the ECG tracing as a string and that you are pulling on both ends. Everything, including the QRS complex and intervals, gets wider.

What are your experiences with this?

Atrial flutter at 150 bpm:
  • Standard rate 25 mm/sec 

  • Faster rate 50 mm/sec (red arrows are flutter waves)

Thanks to Dr. Amal Mattu for sharing his ECGs with me from his University of Maryland ECG archives . If you haven't heard of this amazing ECG video series, you should definitely check it out.

Below is the video teaching this point within the topic of narrow-complex regular tachycardias. This trick is seen at the 15:00 minute mark.

For another example, check out Dr. John Larkin's blog ECG of the Week post on a pediatric SVT rhythm at 300 bpm with no P waves seen at 50 mm/sec.

Accardi AJ, Miller R, Holmes JF. Enhanced diagnosis of narrow complex tachycardias with increased electrocardiograph speed. J Emerg Med. 2002 Feb;22(2):123-6. Pubmed

Gaspar JL, Body R. Best evidence topic report. Differential diagnosis of narrow complex tachycardias by increasing electrocardiograph speed. Emerg Med J. 2005 Oct;22(10):730-2. Pubmed Free PDF
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