Electrophysiology Section, Division of Cardiology, Department of Medicine, University of Colorado, Denver, Colorado 80045, USA.
J Cardiovasc Electrophysiol. 2013 Mar;24(3):297-304. doi: 10.1111/jce.12020. Epub 2012 Oct 30.
Fascicular tachycardia (FT) is an uncommon cause of monomorphic sustained ventricular tachycardia (VT). We describe 6 cases of FT with multiform QRS morphologies.
Six of 823 consecutive VT cases were retrospectively analyzed and found attributable to FT with multiform QRS patterns, with 3 cases exhibiting narrow QRS VT as well. All underwent electrophysiology study including fascicular potential mapping, entrainment pacing, and electroanatomic mapping. The first 3 cases describe similar multiform VT patterns with successful ablation in the upper mid septum. Initially, a right bundle branch block (RBBB) VT with superior axis was induced. Radiofrequency catheter ablation (RFCA) targeting the left posterior fascicle (LPF) resulted in a second VT with RBBB inferior axis. RFCA in the upper septum just apical to the LBB potential abolished VT in all cases. Cases 4 and 5 showed RBBB VT with alternating fascicular block compatible with upper septal dependent VT, resulting in bundle branch reentrant VT (BBRT) after ablation of LPF and left anterior fascicle (LAF). Finally, Cases 5 and 6 demonstrated spontaneous shift in QRS morphology during VT, implicating participation of a third fascicle. In Case 6, successful ablation was achieved over the proximal LAF, likely representing insertion of the auxiliary fascicle near the proximal LAF.
Multiform FTs show a reentrant mechanism using multiple fascicular branches. We hypothesize that retrograde conduction over the septal fascicle produces alternate fascicular patterns as well as narrow VT forms. Ablation of the respective fascicle was successful in abolishing FT but does not preclude development of BBRT unless septal fascicle is targeted and ablated.
纤维性心动过速（FT）是一种少见的单形性持续性室性心动过速（VT）的原因。我们描述了 6 例伴有多形性 QRS 形态的 FT。
对 823 例连续 VT 病例进行回顾性分析，发现其中 6 例归因于伴有多形性 QRS 模式的 FT，其中 3 例表现为窄 QRS VT。所有患者均行电生理研究，包括纤维束电位标测、夺获起搏和电解剖标测。前 3 例描述了相似的多形性 VT 模式，在上中隔成功消融。最初，诱发了一个右束支传导阻滞（RBBB）VT，伴上腔轴。针对左后纤维（LPF）的射频导管消融（RFCA）导致第二个 RBBB 下腔轴的 VT。在上隔的近心尖部消融左后束电位上方的上隔，所有病例均消除了 VT。病例 4 和 5 显示 RBBB VT 伴有交替的纤维束阻滞，与上隔依赖的 VT 一致，导致 LPF 和左前纤维（LAF）消融后出现束支折返性 VT（BBRT）。最后，病例 5 和 6 在 VT 期间显示 QRS 形态的自发变化，提示第三纤维束的参与。在病例 6 中，在近端 LAF 上成功消融，可能代表辅助纤维束在近端 LAF 附近插入。
多形性 FT 显示使用多个纤维束分支的折返机制。我们假设，隔束的逆行传导产生交替的纤维束模式以及窄 VT 形式。消融相应的纤维束可成功消除 FT，但不能排除 BBRT 的发生，除非目标是隔束并进行消融。
