Differentiating Between Right and Left Ventricular Outflow Tract Tachycardia

Right ventricular outflow tract (RVOT) tachycardia is associated with two conditions, idiopathic ventricular tachycardia and arrhythmogenic right ventricular dysplasia.  RVOT make up around 90% of the common form of idiopathic ventricular tachycardia. The mechanism of idiopathic VT is c-AMP mediated activity and hence usually responds to adenosine. Arrhythmogenic right ventricular dysplasia is an inherited disorder which involves fibro-fatty deposition within the myocardium. This disorder causes paroxysmal ventricular tachycardia and sudden cardiac death.  Triggers of RVOT include ….

ECG Findings

RVOT will demonstrate the following characteristics in an electrocardiogram:

  1. Broad Complex Tachycardia
  2. QRS widened >120sec
  3. LBBB- like morphology
  4. No R-wave seen in V1-V2

In RVOT, there can also be the presence of a septal or lateral wall involvement.

In lateral wall involvement there will be a wider and notched QRS complex whereas the opposite will be true of a septal wall RVOT tachycardia. Additionally, a positive QRS complex in aVL indicates lateral wall involvement whereas a negative QRS in aVL indicates septal wall involvement.

The opposite can be said about lateral wall and septal wall involvement in regards to polarity in aVL when discussing LVOT tachycardias. That is, a positive deflection in aVL indicates septal wall involvement whereas a negative deflection in aVL indicates lateral wall involvement.


In contrast, the left ventricular outflow tract tachycardia can demonstrate the following characteristics:

  1. Broad Complex Tachycardia
  2. QRS widened between 100-140sec
  3. RBBB- like morphology

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