左后分支室速的机制

Mechanisms of left posterior fascicular tachycardia

左后分支室速的机制是心室肌参与的大折返,其折返环包括一部分左后分支、P1、连接心室肌和近端P1的缓慢传导区。对于能够记录到P1电位的左后分支室速,理想的消融靶点是P1电位（距P1和P2连接点略近端的位置）,消融终点是窦律下出现P1电位;对于不能记录到P1电位的左后分支室速,需要精确定位最早的P2电位进行消融。

The mechanism of left posterior fascicular ventricular tachycardia is macro-reentry involving the ventricular myocardium. The reentrant loop comprises of a part of the left posterior fascicle,a P1 fiber,a slow conduction zone connecting the ventricular myocardium and proximal P1. In the LPF-VT patients with a recorded P1,the optimal ablation target should be slightly proximal to the connection point between P1 and P2,and the endpoint of ablation is the appearance of P1 during sinus rhythm. In the cases without a recorded P1,the ablation target should be located carefully to the earliest portion of P2.