伴右心室出口的左心室起源缺血性室性心动过速的标测和消融

Ischemic ventricular tachycardia with left ventricular origin in patients with old myocardial infarction

目的折返性的缺血性室性心动过速（VT）绝大多数发生于左心室并表现为右束支阻滞（RBBB）图形。本文报道1组VT折返环位于左心室但出口在右心室且表现为左束支阻滞（LBBB）的病例。方法32例因陈旧性心肌梗死伴VT而接受电生理检查和射频消融的患者，其中4例临床有LBBB形态的VT。使用非接触等电位和虚拟单极标测判断VT起源，结合舒张中期电位（MDP）和拖带标测确定折返关键通路和消融靶点。用盐水冲洗电极导管在折返环的关键峡部行线性消融。结果全部32例患者中，4例临床有LBBB型VT者均成功被诱发，其中1例有两种LBBB型VT，1例同时有RBBB型VT但周长与LBBB型相同；另有1例共有6种形态的VT，包括RBBB和LBBB型。在右心室内的非接触式等电位标测可迅速确定VT在右心室的传出部位，该处的虚拟单极标测显示rS型提示左心室起源。3例在左心室成功拖带并消融成功，靶点均紧邻左心室间隔，其中1例位于下壁，1例在前壁，1例两种LBBB型VT分别在前壁和下壁间隔旁消融成功。随访1～4．2年，未服抗心律失常药无VT发作。而1例诱发出6种单形（包括RBBB和LBBB型）VT患者因巨大室壁瘤及心功能障碍不能耐受而中途放弃消融。结论紧邻室间隔的前壁和下壁心肌梗死后的左心室起源VT可能因在右心室有出口而表现为LBBB型，需要在标测和消融时予以注意。

Objective Ischemic reentrant ventricular tachycardia （VT）usually exhibits right bundle branch block（RBBB） type with left ventricular（LV） origin. VT with left bundle branch block（LBBB） morphology may lead to a misjudgment of the origin. The objective of this study is to investigate VT originated from LV with exit in right ventricular（RV）. Methods Thirty-two patients with history of old myocardial infarction and VT were referred for electrophysiological study and catheter ablation. The reentrant circuits and the ablation tar- gets of VT were determined by isopotential mapping combined with dynamic substrate and successful entrain- ment. mapping Results LBBB type VT was successfully induced in 4 of 32 patients by endocardial stimulation. of them, 1 had two LBBB VT, 1 had both right bundle branch block（RBBB） and LBBB VT with same cycle length, and 1 had 6 VT（ including RBBB and LBBB types）. Isopotential mapping in RV identified break out site where virtual unipolar mapping showed rS. Ablation succeeded in LV in 3 patients just adjacent to septum either on anterior or inferior wall and there was no recurrence reported during 1-4. 2 years follow-up. Ablation was aborted in the patient with 6 VT due to cardiac dysfunction and epicardial origin. Conclusion The LV myocardial infarction at anterior and/or interior wall adjacent to septum may have reentrant VT with remote exit in RV which showed LBBB morphology.