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LVOT Ventricular Tachycardia

Left Ventricular Outflow Tract (LVOT) Tachycardia, Adenosine Sensitive VT

Ventricular Tachycardias from the Outflow Tract

• VT in the context of arrhythmogenic right ventricular dysplasia in the outflow tract area
• It is not idiopathic VT because it involves a structurally altered right ventricle (including the outflow tract)
• Ventricular tachycardias from the outflow tract are mostly idiopathic
• We recognize 2 idiopathic VTs from the outflow tract:
• Ventricular tachycardia from the right ventricular outflow tract
• Ventricular tachycardia from the left ventricular outflow tract
• Mechanism is triggered activity
• They respond well to adenosine, so they are often referred to as adenosine-sensitive VTs
• VTs from the outflow tract in arrhythmogenic right ventricular dysplasia do not respond to adenosine
• Ventricular outflow tachycardias are
• 90% nondurable monomorphic VTs
• Sometimes only numerous ventricular extrasystoles are present without VT
• Extrasystoles occur at rest and disappear with physical exertion
• 10% durable monomorphic VTs
• Occur with physical exertion

ECG and Tachycardia from the Left Ventricular Outflow Tract

• Shape of left Tawar bundle branch block (rarely resembles right Tawar bundle branch block)
• Wide QRS complexes
• Deep S (V1)
• Dominant R (V6)
• Positive QRS in inferior leads (II, III, aVF)
• Transition zone ≤ V2
• VT from the right ventricular outflow tract has a transition zone > V2
• Features of ventricular tachycardia are present
  
  
• VT from the left ventricular outflow tract has compared to VT from the right tract:
• Wide R wave in V1-2 (more than 50% of the QRS width)
• Higher R wave in V1-2 (more than 30% of the S wave)
• Transition zone ≤ V2
• Notch on the ascending part of the R wave (V5-6)

Ventricular Extrasystole from the Left Ventricular Outflow Tract

• On the ECG, we see 1 QRS complex (ventricular extrasystole)
• Wide QRS complex (>0.12s)
• Pattern of right Tawar bundle branch block
• Dominant R (V1)
• Deep S (I, aVL)
• Vertical axis
• Positive QRS (II, III, aVF)
• Transition zone (V1)
• Transition zone ≤ V2 indicates left outflow tract
• Wide R wave in V1 (more than 50% of the QRS width)
• Higher R wave in V1 (more than 30% of the S wave)

Ventricular Tachycardia from the Right Ventricular Outflow Tract

• Heart rate: 150/min.
• Wide QRS complexes (>0.12s)
• Transition zone (V4)
• The location of the transition zone differentiates VT from the right and left outflow tracts
• Transition zone > V2 indicates right outflow tract
• Pattern of left Tawar bundle branch block
• Wide QRS complexes
• Deep S (V1)
• Dominant R (V6)
• Vertical axis (+ 120°)
• Positive QRS (II, III, aVF)
• Ectopic focus is located in the anterior wall of the right ventricle
• Negative QRS in lead I
• Transition zone V4