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Junctional tachycardia

ECG Basics: Accelerated Junctional Rhythm Overriding Normal Sinus Rhythm

Wed, 05/17/2017 - 15:01 -- Dawn

This strip shows a junctional rhythm at a rate of 110 beats per minute. The QRS complexes are slightly wide at .10 seconds (100 ms), and they are within the parameters for supraventricular rhythm. The term, "junctional tachycardia" could be used, also, but this is not likely a "reentrant" junctional tachycardia, which would be fast, regular, and have a sudden onset. That type of junctional tachycardia is a PSVT.   In this strip, we can see the underlying sinus rhythm in P waves that appear to pop up randomly.  However, if you march out the P waves, you will find that they are regular, at a rate of about 90 per minute.  The junctional rhythm has overrun the sinus rhythm.  Most of the P waves cannot conduct due to where they have landed - in the refractory period of the QRS.  The exception might be the P wave after the fifth QRS.  The sixth QRS might be conducted from that P wave.

When accelerated junctional rhythm is encountered, you should suspect DIGITALIS TOXICITY - the classic dysrhythmia associated with digitalis toxicity is accelerated junctional rhythm. Other causes in adults could be beta-agonist drugs such as adrenalin, cardiac infection, ischemia, or surgery.
 

ECG Challenge: Grouped Beating - Double Tachycardia - ANSWER

Tue, 02/03/2015 - 19:06 -- Dawn

This series of strips was donated by Arnel Carmona, and was taken from a patient admitted to the hospital for a urinary tract infection.  No other history is known.   On close examination of this rhythm what do we see?

Strip 1:   Narrow-complex tachycardia with NO apparent P waves.

Strip 2:   Some irregularity, with long regular groups and still NO P waves.

Strips 3 & 4:  Grouped beating.

Strip 5:   A narrow-complex rhythm that is approximately ½ the rate of Strip 1. 

When grouped beating is seen, one should always suspect Wenckebach conduction.  Wenckebach conduction (progressively longer conduction times through the A-V conduction system) can occur in rhythyms other than sinus rhythm.  Without P waves and PR intervals, GROUPED BEATING is our major clue to Wenckebach conduction. 

This patient has an underlying atrial fibrillation – hence no P waves.  Fine fibrillatory waves can be seen, but artifact can cause the same appearance.  So, why is there no irregular irregularity?  There is another rhythm at work here along with the atrial fibrillation.  Junctional tachycardia is seen in Strip 1.  When two tachycardias coexist, one from above the AV junction, and one from below, the rhythm can be called a “double tachycardia”.  This particular combination often happens in patients with digitalis toxicity. 

In some cases, a complete heart block at the level of the atrial conduction fibers or the AV node causes  two rhythms to operate independently.  Any supraventricular rhythm, including atrial fib, can occur with a complete heart block, in which case we would see an “escape” rhythm.  Escape rhythms are usually slow, either idiojunctional (40-60 bpm) or idioventricular (< 40 bpm).  

 Let’s look at each of the strips in detail.  We will begin with the hypothesis that this is atrial fibrillation with concurrent junctional tachycardia at around 150 bpm.  I will include laddergrams to illustrate my view of what is happening. 

ECG Challenge: Grouped Beating - Double Tachycardia

Sun, 01/25/2015 - 17:42 -- Dawn

This very interesting set of strips was donated to the ECG Guru by Arnel Carmona, well-known to many of you as the Administrator of the blog, "ECG Rhythms" and the FB page by the same name.  He is a frequent contributer to the FB page, "EKG Club", and is an ECG Guru!  This set of strips was previously posted to his blog and to the EKG Club.  In case you haven't already seen it, we will withhold the interpretation for now to give everyone a chance to comment.  In one week, we will post the interpretation.

SEE THE INTERPRETATION AT THIS LINK

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