Posts Tagged ‘svt with aberrancy’

Scientific studies can be fun .In our spare time we often Indulge in rapid  fire sessions. We tested 30  wide qrs ECGs from our archives  (All proven VTs)  and  asked  our  cardiology fellows to apply Brugada criteria . They could   correctly  diagnose  VT  in 18* patients.The same ECGs were shown to the staff nurses of coronary care unit . 24  VTs were correctly identified  it.They did it by  their clinical sense and Instinct. (*12 vs 6  VTs missed)

wide qrs tachycardia svt with aberrancy and vt brugada verecki  griffith002

And now , four  clinical data was  provided. (Age , sex , Blood pressure , and  past H/o  MI were given )   The Nurses were able to predict it  28/30  VTs correctly.(97 % accuracy ) and the cardiologists  were able to equal the score now. So obviously clinical sense  was far superior .

Cardiology fellows were more likely to  mistake VT as SVT. This is far more common than SVT mistaken as VT. It is a strange academic  irony ,even the junior most nurses never missed a VT !


Simple sequence of history and clinical presentation is still far more powerful than ECG data in predicting wide qrs  arrhythmias . Nurses guess work is far superior than cardiologists  in predicting a wide QRS tachycardia as VT.

In fact , the  cardiology fellows are  preconditioned to   get confused   whenever they get a wide qrs tachycardia . Why  not aberrancy ?  In my  experience I have seen this question keeps  erupting inappropriately .Even  shrewd fellows suffer  from an  oscillatory  mind between VT and SVT .This is primarily because , every wide qrs ECG  is likely to  have at least two  criteria that fulfill both VT and SVT.

The implications are  genuine  and far reaching . While nurses  show a patient centric thinking  cardiology fellows  thought process revolves around ECG . Many modern-day cardiac physicians  are disconnected from clinical reality  and are obsessed with  complex EP concepts  and end up with a miserable face in the bed side !

This is not a new  revelation in 2013 . Masood Akthar told this  three decades ago.

Never try to glorify  guess-work . EP is a great science .The  pioneering concepts have made us understand how a VT emanates, travels , and exit from myocardium . We are able to localise it and ablate it .All credit goes to science . But , when it comes to bedside recognition of VT ,  clinical  sense  is a clear winner .With a  consistently > 90 % predictive value   it  can no longer be called as  a  guesswork   and becomes a hard scientific fact. Especially so , when the  intellectual  analysis of surface ECG   could predict  it  with paltry 70 %  accuracy (Read Reference 1)
This  analysis startlingly reveal  a fact .The over all accuracy  rate of predicting the wide qrs criteria  by  popular algorithms  is   between 66-77% ,  just 16 numerals   more than  gross   guess work  of 50 : 50 ( This  . . . or  . . . that )
Link to  Masood Akthar article

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Irregular  wide qrs tachycardia is a fairly common clinical entity in any cardiac emergency room. The moment you ask about  such tachycardia ,  9/10  fellows will  come out with a  prompt answer   ” AF with WPW syndrome” even before you complete the question !  It is not that common  as we perceive .The problem is with  our traditional teaching methods and the attraction of human brains to  rare and exotic disorders.

traditionally   SVT with aberrancy  is   diagnosed  mainly  in the setting of regular tachycardia .

We often  forget  “AF with aberrancy”  is equally common  , and  it presents   with a  irregular  wide qrs tachycardia . 

I  wonder whether  this phenomenon  can be termed as  orthodromic aberrancy .This can directly compete  in the differential diagnosis  of  antidromic AF  with  WPW !

It should also be mentioned antidromic  AF can run into very high rates  as accessory pathways do not check the incoming signals while orthodromic aberrancy the ventricular rates can not exceed 220 or so at least theoretically . (This simple clue can clinch the issue in favor of  WPW )

There is no proper  published data available for the true  incidence of AF with orthodromic aberrancy in general population

In fact , there are  many  electrical  environments for AF  to  become a  wide qrs AF

1. AF  with  Antidromic conduction through accessory WPW pathway.

2. AF with Orthodromic aberrancy ( Non WPW – Similar to  any SVT with aberrancy )

3. AF with pre existing LBBB

4. AF  with Amiodarone effect. (Especially with DCM and cumulative load of Amiodarone )

5. AF with electrolytic /  especially excess  intra-cellualr  potassium

6. Finally , even  Atrial based pacing (DDD)  can cause wide qrs irregular tachycardia when  mode switching  fails .Here the  ventricles  may track the  atrial irregularity  and respond with a  wide qrs  bizarre tachycardia .

Final message

There are many causes for  wide qrs tachycardias  in  Atrial fibrillation . WPW with anti-dromic conduction is just  one of them .We need to approach the issue with an open mind .Please  be reminded , once contemplated  WPW syndrome  can be a powerful thought blocker  !

Note : *We are not including   polymorphic ventricular tachycardia here .It is an  important subset of  wide qrs irregular  tachycardia.

** VT can co-exist with AF .This is not   surprising  as  many of the diffuse cardiomyopathies  involve  both atria and ventricle  with extensive scarring and fibrosis  a perfect trigger for  both atrial and ventricular arrhythmias .

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