Dr.S.Venkatesan MD

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

The greatness of  this  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 ?

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  are the  difficulties  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 !  .Even though 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 !