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Why is absent RS complex in precardial leads is very sacred to diagnose VT ?

Posted Sep 17 2009 10:21pm

The most popular criteria to differentiate VT from SVT aberrancy is  formulated by Brugada in 1991.

The greatness of that criteria is that  a single question asked  is able to confirm VT in vast majority of cases.

Is RS complex absent all  of the pericardial leads ?If  the answer is  yes  it is VT 100%

How is that,  we have been struggling for so long , a single question is able to solve the issue quite easily ?

wide qrs tachycardia vt svt aberrancy brugada

This is because , the term  “Absent RS complex ” actually means

Presence of  one of the  following three typical complexes Of VT.

  1. QS
  2. QR
  3. Monophasic R

Two of them  actually imply ,  q waves throughout   V 1-V6 .This  means a badly damaged ventricle and  with  little electrical activity coming towards the chest wall .This situation  almost always occur in VT.*

The third complex is Monophasic R .

A  monophasic , wide  QRS  complex  again indicate VT  as monophasic aberrancy is very rare as the supraventricular  impulse invariably conducts with  RSr’  ( The right bundle  refractory period sees to that  at least a small r’ is inscribed however fast the SVT is !  )

So if there is no RS complex  it must be VT !

What is the most important difficulty faced in applying this  first

step of Brugada criteria ?

It is funny to note , in medicine criterias  often work perfectly in  text books only !

Is there a RS complex seems to be a very easy question ? There lies the catch !  .Eventhough this criteria may be 100% specific , differentiating RS from QS complex even by an experienced cardiologist may be difficult in a significant number of VT tracings.This  realistically ,  reduces    supposedly  100% specificity  of this criteria !

In fact we expect Brugada to develop an  another limb  to his now famous algorithm

Is there  absence  RS complex in precardial leads  ?  Yes / No / May be ,  not sure!

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