心房内双环折返性心动过速的非接触球囊导管标测及射频消融

目的 阐明心房内双环折返性心动过速的电生理机制及导管射频消融的技术。方法 3例患，均为女性，年龄41-66岁，心动过速病史6个月-10年，例1为先天性心脏病房间隔缺损修补术后，例2为特发性心动过速，例3为扩张型心肌病，经左股静脉置入9F球囊电极至右心房中部并展开，球囊中心位于希氏束和冠状静脉窦口中间，进入球囊时，静脉注射肝素100U/kg，并保持手术过程中活化的血小板凝结时间（ACT）位于250s左右，以后经右股静脉进入8F消融导管构建右心房三维几何构型，构型构建完毕后，经高位右心房诱发心动过速，建立心动过速的腔内等电势图，然后分析心动过速的起源，折返激动的环路，传导方向，关键峡部，由此确定线性消融的部位和起止点，经导航系统引导消融导管至拟订靶点处，每点予以60W，60s,60℃温控消融，直至产生消融线径的双向阻滞。结果 3例患均有心房内双环折返性房性心动过速（房速），折返环分别围绕三尖瓣环和病变组织周围，于各自的峡部行线性消融产生双向阻滞后，心动过速不再诱发，随访分别为3、5和12个月，无心动过速复发，例2术后动态心电图记录有频繁房性早搏，部分房性早搏触发短阵心房颤动。结论 心房内存在病变组织如手术瘢痕，补片及梗死病灶时可产生心房内折返，若合并围绕三尖瓣环折返的典型心房扑动则形成心房内双环折返性房速。双环折返性房速也可发生在无器质性心脏病的患，不同的基础心脏病变决定着不同的折返环路和折返方式，双环折返性房速存在两个关键峡部，需要两次线性消融才可阻止心动过速的发生，非接触球囊导管标测系统（EnSite3000)不同可破译心房内双环折返性心动过速的电生理机制，也为其消融方法提供可靠的策略。

Noncontact mapping and radiofrequency catheter ablation of intra-atrial dual-loop reentrant tachycardia

Objective To illustrate the mechanisms of intra atrial dual loop tachycardia and its catheter radiofrequency ablation technique. Methods Three cases,all female,aged from 41 to 66 years, had the history of tachycardia for 6 months to 10 years. Case 1 had atrial septal defect repair 23 years ago, and Case 2 had no structural heart disease, and Case 3 had idiopathic dilated cardiomyopathy.9 French balloon catheter was advanced via left femoral vein to the right atrium and deployed at the level between His bundle and coronary sinus. Heparin was used to keep ACT(activative coagulation time) level around 250 s during the procedure.8 French deflectable catheter was inserted through right femoral vein to make geometry of right atrium.Complete tachycardia mapping was performed in the right atrium with noncontact mapping system (EnSite3000), followed by linear radiofrequency ablation of the narrowest part of each complete loop.Results Two different tachycardias could be induced in each of 3 cases.All cases had clockwise cavotricuspid isthmus dependent atrial flutter.In addition,Case 1 had atrial tachycardia going around atriotomy scar counter clockwisely,Case 2 around the upper part of crista terminalis clockwisely, and Case 3 around scar tissue clockwisely.Linear ablation was done in both cavotricuspid isthmus and critical isthmus of atrial tachycardia under the guidance of EnSite3000 guiding system.No tachycardia could be induced after the procedure.There was no recurrence after follow up of 3-12 months.Conclusions Dual loop atrial reentrant tachycardia can occur in both diseased atrium and nondiseased atrium. Noncontact mapping is a good way for such tachycardias not only for its mapping property but also for its guiding system.Linear ablation should be done in two isthmuses in these cases.