Idiopathic Left Ventricular Tachycardia Originating in the Left Posterior Fascicle

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Anatomy

Background:

• Idiopathic left ventricular tachycardia (ILVT) commonly arises from the Purkinje system.
• The reentrant circuit for ILVT is predominantly formed by Purkinje fibers of the left bundle branch, especially the left posterior fascicle.

Purpose of the Study:

• To elucidate the specific roles of slow (P1) and normal (P2) conducting Purkinje fibers in the reentrant circuit of left posterior fascicular VT.
• To identify critical ablation targets within the Purkinje system for successful treatment of ILVT.

Main Methods:

• Activation mapping to delineate the reentrant circuit during ventricular tachycardia.
• Analysis of His-ventricular intervals during sinus rhythm and tachycardia to pinpoint critical sites.

Main Results:

• Slowly conducting Purkinje fibers (P1) typically form the antegrade limb of the reentrant circuit.
• Normally conducting Purkinje fibers (P2) generally constitute the retrograde limb of the circuit.
• Differences in His-ventricular intervals effectively identify critical components of the reentrant pathway.

Conclusions:

• Successful ablation of left posterior fascicular VT requires elimination of critical Purkinje elements within the reentrant circuit.
• Activation mapping combined with His-ventricular interval analysis provides a roadmap for precise ablation targeting.