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Ventricular Tachycardia

Sat, 11/24/2012 - 15:52 -- Dawn

This is a good example of ventricular tachycardia with PRECORDIAL CONCORDANCE.  The QRS complexes in the chest, or precordial, leads all point downward.  When the precordial leads are all  negative or all positive in a wide-complex tachycardia, there is virtually a 100% chance that the WCT is ventricular tachycardia.  This ECG shows many characteristics of VT, including the extreme "backwards" axis:  aVR is positive and II, III, and aVF are negative.  Lead I is almost equiphasic.  Also, the lack of a clear BBB pattern and a negative V6 are strongly suggestive of VT.  REMEMBER:  In the treatment of wide-complex tachycardia, the rhythm should be considered VT unless proven otherwise.  This is especially true in unstable patients, patients over 50 years old, and patients with known heart disease.

INSTRUCTORS' NOTE:  We purposely left the machine interpretation on this week's ECG of the Week.  How many errors did the machine make?  This might be a good teaching point for students of all levels.

 

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ekgpress's picture
Submitted by ekgpress on

GREAT illustrative tracing by Dawn. I love her point about the computer interpretation. There are Pros and Cons in using computerized ECG interpretations - but this tracing brings home the point that IF a computerized interpretation ever says anything but "sinus rhythm" - Do NOT believe it! I do not think there will ever be an adequate computerized program for rhythm interpretation (For anyone interested in brief Review on Computerized tracings plus a series of ECGs with answers on "computer mishaps" - GO TO: https://www.kg-ekgpress.com/computerized_ecg_interpretations/ ).

But the MAIN point about this wonderful example is HOW MANY WAYS YOU CAN DIAGNOSE VT on this tracing. Just count the ways:

  1. Dawn's reference to precordial concordance (in this case negative concordance - that tiny r that Marionurse points out notwithstanding the 'theme' of global negativity). Finding global concordance (all positive or all negative complexes in V1-thru-V6) is not a sensitive criterion (found in <10% of VT cases) - but when found is 100% specific for VT.
  2. Bizarre axis deviation as Dawn points out (all negative complex in the inferior leads).
  3. Lack of a clear BBB pattern as Dawn points out (and which I take journalistic liberty by saing the QRS complex is UGLY). An "ugly" QRS means you are unlikely to be conducting through the bundle branch system ...
  4. The QRS is very wide (looks to be at least 0.15 sec in some leads).
  5. Lead aVR is all positive! This is another insensitive but HIGHLY SPECIFIC criteria - that when found virtually ensures VT.
  6. No RS complex is seen in any precordial lead (even if that is a tiny r in V1 - there really isn't an RS = positive and negative deflection complex in any precordial lead) - which is virtually diagnostic of VT.
  7. Lead V6 is all negative (there is almost always at least some positive activity in V6 when there is supraventricular conduction ... ).
  8. This looks like VT ....

FINAL POINT - We can also say 100% that this is NOT WPW - because the QRS in leads V4,5,6 is all negative. This means the impulse arises near the apex - and no accessory pathways originate down there ...

GREAT teaching tracing Dawn!

P.S. For anyone interested - I review VT vs Aberrancy criteria at: https://www.kg-ekgpress.com/acls_comments-_issue_11/

Ken Grauer, MD  www.kg-ekgpress.com   ekgpress@mac.com