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.
- 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 !