隐匿性束室纤维介导的心动过速(附一例报告)

目的 阐明隐匿性束室纤维介导的心动过速的电生理机制及其导管消融方法。方法 研究病例为男性、29岁，心动过速病史7年余。心动过速不能被腺苷三磷酸和维拉帕米终止，但可被普罗帕酮终止。曾在院外拟诊房室结折返性心动过速，两次行慢径改良术，但心动过速仍反复反作。在我院行电生理检查一次并在非接触球囊导管标测系统（即EnSite,3000）指导下标测和消融。结果 电生理检查示窦性心律时AH为75ms，HV 44ms，心房增频刺激及程序刺激未见心室预激现象。心室600ms起搏示室房分离，RS2程序刺激无逆传A波，提示室房逆传功能较弱。心房与心室均能诱发心动过速，但心室更易诱发。心动过速时室房分离。心动过速可呈窄QRS图形、左束支传导阻滞（LBBB）图形及右束支传导阻滞（RBBB）图形。LBBB和RBBB心动过速可自行转为窄QRS心动过速。窄QRS心动过速及RBBB图形时，心动周期为300ms；LBBB图形时，心动周期为316ms，明显长于前。三种心动过速时，希氏束激动均领先于右束支激动。维拉帕米和腺苷三磷酸不能终止心动过速。专房程序刺激及超速抑制不能终止心动过速，但可被心室程序刺激终止。EnSite 3000标测系统分析发现三种心动过速的最先激动点均位于心动过速的最先活动点均位于右室间隔上部，此处行环状消融后心动过速不再诱发。随访4个月，临床无心动过速发作。结论 该患的心动过速由隐匿性束室纤维介导，其折返环路包括正常的希－浦传导系统、心室和束室纤维，其消融方法与室性心动过速相似；EnSite3000标测系统指导此类心动过速的消融有极大的优越性。

Concealed fasciculoventricular fiber in the genesis of paroxysmal tachycardias (with one case report)

Objective　To illustrate the electrophysiologic mechanisms of tachycardia mediated by concealed fasciculoventricular fiber and its proper catheter ablation method. Methods　The studied case, male, 29 years old, had a history of tachycardia for more than 7 years. The tachycardia could be terminated by propanfenone, but could not by ATP and verapamil. Careful electrophysiological study was performed 3 times before catheter ablation. Mapping and ablation therapy for the tachycardia was guided by EnSite 3000 mapping system. Results　AH interval was 75 ms and HV 44 ms during sinus rhythm. No preexcitation phenomenon could be found during incremental atrial pacing. VA dissociation was present during ventricular pacing at a drive length of 600 ms. The tachycardia could be induced both by programmed atrial and ventricular stimulation, but more easily by ventricular stimulation. The QRS complex, during tachycardia could be in morphology of narrow,left bundle branch block (LBBB) and right bundle branch block(RBBB) with VA dissociation. Wide QRS complex could change to narrow one automatically during tachycardia. Right bundle branch activation was earlier than His in all three kinds of tachycardia. ATP and verapamil could not terminate the tachycardia. Atrial overdrive pacing and programmed stimulation failed to stop the tachycardia but ventricular stimulation did successfully. The cycle length was 300 ms in tachycardia with narrow QRS and RBBB, but prolonged to 316 ms in tachycardia with LBBB. The earliest activation spot was mapped in upper part of the right septum using EnSite 3000 mapping system and circular ablation was done here. The tachycardia could not be induced after ablation and no tachycardia occurred during follow-up of 4 months. Conclusions　The tachycardia was mediated by concealed fasciculoventricular fiber. The reentrant circuit incorporates normal His-Purkinje conduction system, the ventricle and the fasciculo-ventricular fiber. Radiofrequency catheter ablation guided by EnSite 3000 mapping system can successully eliminate the tachycardia.