Ventricular Tachycardia

Creado por team@ekgdx.com el 9 de Diciembre de 2023

Let’s talk about Ventricular Tachycardia (VT).

Ventricular tachycardia (VT) is characterized by a rapid succession of ≥3 premature ventricular complexes at a rate >100 bpm. It is commonly called V-tach.

Criteria

  • Wide QRS (can be with RBBB or LBBB morphology).
  • ≥3 consecutive PVCs with similar morphology at a rate >100 bpm.
  • Regular rhythm (except at the beginning).
  • AV dissociation is diagnostic but not always present, particularly when the rate is fast. 
  • Capture beats can be present and occur when the SA node transiently captures the ventricles producing a narrow QRS complex. 
  • Fusion beats can be present and occur when a sinus and ventricular beat coincide to produce a hybrid complex of intermediate morphology. 

VT can be classified according to duration, morphology or hemodynamic status:

  • Duration: Sustained >30 sec. and Non-sustained <30 sec. 
  • Morphology: Monomorphic when demonstrates identical QRS morphology from beat to beat, excluding fusion and capture beats. Polymorphic when demonstrates wide QRS complexes with different morphology coming from several foci.
  • Hemodynamic status: Unstable may include hypotension, altered mental status, chest pain, etc. Stable are relatively asymptomatic or very minimal symptoms despite the fast rate.

 

Sustained Monomorphic Ventricular Tachycardia

 

Nonsustained ventricular tachycardia (three PVCs in a row)

 

Polymorphic ventricular tachycardia

 

Several algorithms have been developed to differentiate VT from SVT:

1- Brugada criteria

  • Absence of RS complex in all precordial leads (suggests VT).
  • Longest R/S interval >0.10 sec. in any precordial lead (suggests VT). 
  • AV dissociation (suggests VT). 
  • Morphology criteria for VT present in both precordial leads V1-V2 and V6 (suggests VT). 

2- Pava criteria

  • The R wave peak time (RWPT ≥50 ms in lead II) is strongly suggests VT.

3- Wellens criteria

  • QRS width >0.14 sec. (suggests VT).
  • Left axis deviation (suggests VT). 
  • AV dissociation (suggests VT).   
  • If RBBB morphology, monophasic or biphasic QRS in V1 (suggests SVT).
  • If LBBB morphology (suggests VT).

4- Kindwall criteria

  • R duration in V1 or V2 >0.03 sec. (suggests VT).
  • Any Q in V6 (suggests VT). 
  • A duration of greater than 60 ms from the onset of the QRS to the nadir of the S wave in V1 or V2 (suggests VT).   
  • Notching on the downstroke of the S wave in V1 or V2 (suggests VT).

5- The new limb lead algorithm (VT is diagnosed in the presence of at least 1 of the following):

  • Monophasic R wave in lead aVR.
  • Predominantly negative QRS in leads I, II, and III.
  • Opposing QRS complex in the limb leads.

6- Other criteria include: Vereckei 2007, Griffith 1994.

NOTE: VT may present with relatively narrow QRS complex in the presence of idiopathic fascicular tachycardia.

There are three types of idiopathic fascicular ventricular tachycardia:

  • Posterior fascicle (most common): QRS <0.14 sec., RBBB morphology and left axis. Starts in upper septum near bundle of His/proximal LBBB in verapamil-sensitive slow zone, travels toward apex.
  • Anterior fascicle: QRS <0.14 sec., RBBB morphology and right axis. Starts in upper septum near bundle of His/proximal LBBB in verapamil-sensitive slow zone, travels toward anterior fascicle exit.
  • Upper septal fascicle: QRS <0.12 sec., RBBB or normal morphology and normal axis. Circuit likely to involve reverse path of others (namely the fascicle is the antegrade limb). Although not fully characterized, the reason for the narrow QRS may be because of near simultaneous antegrade activation of the left anterior and posterior fascicles with the septal fascicle serving as the retrograde limb.

Possible causes of VT: Myocardial ischemia, MI, coronary artery disease, valvular heart disease, heart failure, cardiomyopathy, hypoxia, acidosis, electrolyte imbalances, digitalis toxicity, abuse of (cocaine, amphetamines, alcohol, etc.), others.

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References

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Dr. Roig

Ventricular Tachycardia