Right Ventricular Outflow Tract Ventricular Tachycardia

Figure 1 - Remote Monitoring

Figure 2 - 12 L lead ECG

Vignette: A 45 yo pt c/o of palpitations with normal EF

The strip shows regular wide QRS tachycardia (~214 bpm). in the 12 lead,  it shows left bundle branch (LBBB) morphology, inferior axis, late precordial R wave transition, positive QRS complexes in the inferior leads and wide notched R waves in I and aVL. Electrophysiological study showed right ventricular outflow tract VT and ablation was done.

Ventricular  tachycardia in patients with normal hearts is called idiopathic VT. There are 2 types - adenosine sensitive idiopathic VT and verapamil sensitive fascicular VT.

The most common form of idiopathic VT originates from the VT outflow tract. Seventy-five to eighty percent originate from the right ventricular outflow tract (RVOT) and the rest can originate anywhere in the ventricles.

RVOT VT have LBBB morphology with precordial R wave transition in lead V3 or V4 and positive QRS complexes in the inferior leads. RVOT can be divided into septal anterior, posterior and lateral walls (Figure 3). 

Figure 3 - Localization of Vt origin by QRS morphology

*Precordial transition - QRS transition in precordial leads with change where R wave becomes greater than S wave. Transition at or beyond lead V4 means late transition.

Reference:

Das and Zipes. 2012. Electrocardiography of arrhythmias : a comprehensive review. Elsevier PA

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