超高密度标测系统对周长交替变化的大折返性房性心动过速机制的探讨

Insight into the mechanism of macroreentrant atrial tachycardia with cycle length alternans using ultrahigh density mapping system

目的探讨周长交替变化的折返性房性心动过速(简称房速)的机制。方法应用超高密度标测系统对武汉亚洲心脏病医院的478例房速进行激动标测,标测发现7例房速存在周长交替现象。分别对该7例患者进行超高密度三维激动标测,长周长心动过速的周长(289±35)m,激动标测采点21520±11103,短周长心动过速的周长(251±18)ms,激动标测采点17594±8059。结果周长交替的房速存在2种类型:类型1:存在2个具有不同传导路径的潜在折返环路。周长交替是由小折返环路的传导通道内的间歇性2∶1传导阻滞导致的。类型2:周长交替是因为原存在的线性损伤病变中两个相邻缝隙的传导速度不同导致的。导管消融成功终止所有7例房速。结论超高密度标测可明确的阐述周长交替变化的房速的机制,传导通道或缝隙存在间歇性传导阻滞或传导延缓是该类心动过速维持的必要因素。

Objective To identify the characteristics and precise mechanism of this special category of atrial tachycardia(AT)by using an ultrahigh density mapping system.Methods Seven ATs with alternating cycle length(CL)were identified in a total of 478ATs from 2institutions mapped with an ultrahigh density mapping system.Activation maps were performed for long CL[(289±35)ms;mapping points,21520±11103]and short CL[(251±18)ms;mapping points,17594±8059]separately.Results We classified ATs with CL alternans into 2 types.Type 1:There existed 2potential loops with different routes.CL alternans resulted from an intermittently 2∶1conducting block within the channel of the smaller loop.Type 2:CL alternans resulted from different conduction velocity through 2closely spaced gaps within preexisting linear lesions.Catheter ablation successfully terminated all the 7ATs.Conclusion Ultrahigh density mapping provides an opportunity to delineate the precise mechanism of AT with CL alternans.Intermittent conduction block or slowing of a channel is essential for themaintenance of AT.[Chinese Journal of Cardiac Pacing and Electrophysiology,2020,34(5):471-476]