Approach to the Wide Complex Tachycardia

During wide complex tachycardia (heart rate > 100/min, QRS > 0.12 sec) the differentiation between supraventricular and ventricular origin of the arrhythmia is important to guide therapy. Several algorhythms have been developed to aid in this differentiation (below). It is important to keep in mind that a good estimate of VT versus SVT can be made based on the clinical vignette:

• 'Horizontal entrance' into the ER. Older patient with previous myocardial infarction = most likely VT
• Younger patient with known paroxysmal tachycardias and who is hemodynamically stable = most like SVT

The ACC algorhythm ACC

SVT vs VT algorhytm. Adapted from ACC

Brugada criteria

Brugada criteria to differentiate SVT from VT Brug1
Are there fusion or capture beats? (this is not an item from Brugada, it is however very specific	Yes? => VT	specificy=100%
RS complexen missing in the chest leads?	Yes? => VT	sensitivity=21% specificity=100%
RS-interval in one of the cheast leads > 100 msec (in the absence of anti-arrhythmics)?	Yes? => VT	sensitivity=66% specificity=98%
AV-dissociation?	Yes? => probably VT (Note AVNRT can also present with AV dissociation!)	sensitivity=82% specifity=98%
Morphological criteria (if the above criteria are inconclusive)
LBBB pattern
Initial R more than 40ms?	Yes => VT
Slurred or notched downwards leg of S wave in leads V1 or V2	Yes => VT
Beginning of Q to nadir QS >60 ms in V1 or V2?	Yes => VT	LR >50:1
Q or QS in V6?	Yes => VT	LR >50:1
RBBB pattern
Monofasic R or qR in V1?	Yes => VT
R taller than R' (rabbit-ear sign)?	Yes => VT	LR >50:1
rS in V6?	Yes => VT	LR >50:1

Vereckei algorithm Vereckei

If the distance traveled on the Y axis in the initial 40ms of the QRS complex is smaller than that traveled in the terminal 40ms of the QRS complex, a VT is much more likely

Examples

• 
  Wide complex tachycardia. No AV dissociation. RBBB. Resembles sinus rhythm from the same patient. Conclusio SVT with RBBB
• 
  ECG from the same patient in sinus rhythm. The QRS complex is very similiar.
• 
  Wide complex tachycardia. LBBB configuration. Absence of RS in the chest leads. AV dissociation is present. Conclusion: VT
• 
  Wide complex tachycardia. LBBB configuration. Absence of RS in the chest leads. AV dissociation is present. Conclusion: VT

Referenties

<biblio>

1. ACC pmid=14563598
2. Brug1 pmid=2022022
3. Vereckei pmid=17272358

</biblio>