界嵴心动过速与房室结折返性心动过速并存时心房激动的竞争夺获现象

目的　阐明右心房内界嵴心动过速 (CT AT)与房室结折返性心动过速 (AVNRT)并存时心房激动的竞争夺获现象 ,分析其可能的电生理机制及导管消融策略。方法　 3例患者中 ,女性 2例 ,男性 1例 ,年龄 4 9～ 5 7岁 ,心动过速病史 10～ 2 0年。 3例患者均无器质性心脏病。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水平。构建右心房构型后 ,经高位右心房程序刺激诱发心动过速 ,建立心动过速的心内膜等电势图 ,然后分析心动过速的起源、传导方向 ,由此确定消融的部位和方法。经导航系统引导消融导管至拟订靶点处 ,每点予以 6 0W、6 0s、6 0℃温控消融 ,直至心动过速不能诱发。结果　 3例患者均可诱发出CT AT和AVNRT。例 1CT AT和AVNRT同时被诱发 ,两种心动周期比较接近 ,分别为 2 83ms和 2 6 2ms ;心内膜电生理提示心动过速由CT AT逐渐移行成AVNRT。例 2首先诱发出CT AT ,随之又诱发出AVNRT ,且两者并存 ,两种心动周期基本相同 ,分别为 35 0ms和 35 9ms;心内膜电生理示右心房上部随CT激动 ,下部及间隔部随AVNRT激动。例 3AVNRT比CT更易诱发 ,两者不在同一时间段出现 ,前者心动过速周期为 2 73ms ,后者为 36 5ms。3例患者均先行常规方法消融慢径 ,使AVNRT不再诱发。CT AT经非接触球囊导管

Competitive atrium capture during cristal tachycardia coexisting with atrioventricular nodal reentrant tachycardia

Objective To demonstrate the mechanisms of competitive atrium capture during atrial tachycardia arising from crista terminalis (CT AT) coexisting with atrioventricular nodal reentrant tachycardia(AVNRT) and to introduce the mapping method and ablation strategy. Methods Three cases, 2 female, 1 male,aged from 49 to 57 years old, had the history of tachycardia for 10 to 20 years. All cases had no structural heart disease. A nine French balloon catheter was advanced via left femoral vein to the right atrium and deployed at the His level. After the geometry of the right atrium was made and the anatomic location of crista terminalis was marked, complete tachycardia mapping was performed in the right atrium with noncontact mapping system (EnSite 3000),followed by radiofrequency ablation at the earliest activation point. Results CT AT and AVNRT were induced simultaneously in case 1 by high right atrium programmed stimulation, with cycle lengths of 283 ms and 262 ms respectively. Endocardial ECG showed that the atrial activation had the characteristics of both tachycardias. In case 2, CT AT with the cycle length of 350 ms was first induced, which automatically induced AVNRT with the cycle length of 359 ms after a few seconds. During tachycardia, the upper part of the right atrium was captured by CT AT, while the lower and the septal parts were captured by AVNRT. In case 3 ,CT AT and AVNRT did not occur at the same time because of quite different cycle lengths(365 ms and 273 ms). After slow pathway modification was done, all AVNRTs could not be induced. The earliest activation of all CT ATs was at the upper part of the crista terminalis, with the distance from sinus breakout point of 2.0cm,1.8cm,1.7cm respectively. Radiofrequency energy was then delivered to the earliest activation points guided by the noncontact mapping system. All cases were free of symptoms during follow up of 3 6 months. Conclusions When CT AT is coexisting with AVNRT in similar cycle length, the atrium will be captured by both tachycardias competitively, and endocardial ECG will show the characteristics of both tachycardias. If there is a big difference of cycle length between the two tachycardias, the atrium will be fully captured by the faster type of tachycardia or the more easily induced tachycardia. Noncontact mapping system can help to identify crista terminalis, to map CT AT and to guide catheter ablation.