Following the discussion on ectopy and aberrancy (view Ectopy or aberrancy? Google Ecg+ community comments on a clinical case.) Ken Grauer, EKG master and author of many EKG books, gave us the permission to share his “3 SIMPLE Rules” to recognize VT in a simple ad accurate way.
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Rule #1 Is there extreme axis deviation during WCT
Extreme axis deviation is easy to recognize. The QRS complex will be entirely negative in either lead I or lead aVF. The presence of extreme axis deviation during a WCT rhythm is virtually diagnostic of VT.
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Rule #2 Is lead V6 all (or almost all) negative?
IF ever the QRS in lead V6 is either all negative (or almost all negative) then VT is highly likely.
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Rule #3 Is the QRS during WCT “ugly”?
The “uglier” the QRS the more likely the rhythm is. VT originates from a ventricular focus outside of the conduction system. As a result VT is more likely to be wider and far less organized (therefore “uglier”) in its conduction pattern
The “3 simple rules” is an extract from ACLS 2013 Arrhythmias where you can find the complete explanation and much more on arrhythmias.
Visit Ken Grauer Amazon page to find out more and discover all the amzing EKG books he wrote. They are accurate and reliable for use in many emergency situation.
I’ll include Ken’s reply in the main script of the post cause it contains some very important adjuncts and expalnations. At the end of the replay you’ll find the link to download the full text of the section regarding the WCT topic. You’ll also appreciate the perfect Ken’s italian. I’m amazed….
“Molto grazie Mario per la pubblicazione del mio consiglio su le tre semplici regole per diagnosticare VT! I’ll make a few brief additions to what Mario wrote. RULE #1 – Remember that slight or even moderate axis deviation is of no help. The QRS complex must be ALL negative in either lead I or in lead aVF. If it is – then the rhythm is almost always VT. RULE #2 – Again, moderate negativity in lead V6 is common and means nothing. But if the QRS complex in lead V6 is either all negative or shows no more than a tiny r wave – then VT is likely. This is because such marked negativity in lead V6 implies that the impulse is moving away from the apex – and that almost always means VT. RULE #3 – Supraventricular rhythms with either preexisting bundle branch block or aberrant conduction typically resemble some form of conduction defect (ie, either RBBB, LBBB or RBBB with LAHB and/or LPHB). However, if the QRS complex is amorphous (ie, very “ugly” and formless) – then it is much more likely to be originating from the ventricles. Occasionally, patients may have unusual forms of IVCD – so this rule is not 100% accurate – but it is a helpful supportive point in the differential diagnosis. For those wanting more complete description of the 3 Rules (and other pointers in assessing wide tachycardias) – feel free to download these Sections from my ACLS-2013-ePub – GO TO – https://www.dropbox.com/s/8bc9h5cumo7e4vy/8.0%2C9.0%2C10.0-%20ACLS-2013-e-PUB-WCT-Criteria-%2810-13.11-2014%29-LOCK.pdf?dl=0 – Detailed description of the 3 Simple Rules begins in Section 08.17. Spero che questo vi aiuta.”
Ken Grauer
Le tue opinioni sono il nostro valore aggiunto!
MEDEST 
Molto grazie Mario per la pubblicazione del mio consiglio su le tre semplici regole per diagnosticare VT! I’ll make a few brief additions to what Mario wrote. RULE #1 – Remember that slight or even moderate axis deviation is of no help. The QRS complex must be ALL negative in either lead I or in lead aVF. If it is – then the rhythm is almost always VT. RULE #2 – Again, moderate negativity in lead V6 is common and means nothing. But if the QRS complex in lead V6 is either all negative or shows no more than a tiny r wave – then VT is likely. This is because such marked negativity in lead V6 implies that the impulse is moving away from the apex – and that almost always means VT. RULE #3 – Supraventricular rhythms with either preexisting bundle branch block or aberrant conduction typically resemble some form of conduction defect (ie, either RBBB, LBBB or RBBB with LAHB and/or LPHB). However, if the QRS complex is amorphous (ie, very “ugly” and formless) – then it is much more likely to be originating from the ventricles. Occasionally, patients may have unusual forms of IVCD – so this rule is not 100% accurate – but it is a helpful supportive point in the differential diagnosis. For those wanting more complete description of the 3 Rules (and other pointers in assessing wide tachycardias) – feel free to download these Sections from my ACLS-2013-ePub – GO TO – https://www.dropbox.com/s/8bc9h5cumo7e4vy/8.0%2C9.0%2C10.0-%20ACLS-2013-e-PUB-WCT-Criteria-%2810-13.11-2014%29-LOCK.pdf?dl=0 – Detailed description of the 3 Simple Rules begins in Section 08.17. Spero che questo vi aiuta.
Excellent (and easy to remember at the bedside) rule of thumb!