Department of Cardiology, Key Laboratory on Assisted Circulation, Ministry of Health, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China.
Department of Cardiology, The People's Hospital of Guangdong Province, Guangzhou, Guangdong, People's Republic of China.
Pacing Clin Electrophysiol. 2021 Mar;44(3):462-471. doi: 10.1111/pace.14164. Epub 2021 Jan 31.
Epicardial to endocardial breakthrough (EEB) exists widely in atrial arrhythmia and is a cause for intractable cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL). This study aimed to investigate the electrophysiological features of EEB in EEB-related CTI dependent AFL.
Six patients with EEB-related CTI-dependent AFL were identified among 142 consecutive patients who underwent CTI-dependent AFL catheter ablation with an ultra-high-density, high-resolution mapping system in three institutions. Activation maps and ablation procedure were analyzed.
A total of seven EEBs were found in six patients. Four EEBs (including three at the right atrial septum and one in paraseptal isthmus) were recorded in three patients during tachycardia. The other three EEBs were identified at the inferolateral right atrium (RA) during pacing from the coronary sinus. The conduction characteristics through the EEB-mediated structures were evaluated in three patients. Two patients only showed unidirectional conduction. Activation maps indicated that CTI-dependent AFL with EEB at the atrial septum was actually bi-atrial macro-reentrant atrial tachycardia (BiAT). Intensive ablation at the central isthmus could block CTI bidirectionally in four cases. However, ablation targeted at the inferolateral RA EEB was required in two cases. Meanwhile, local potentials at the EEB location gradually split into two components with a change in activation sequence.
EEB is an underlying cause for intractable CTI-dependent AFL. EEB-mediated structure might show unidirectional conduction. CTI-dependent AFL with EEB at the atrial septum may represent BiAT. Intensive ablation targeting the central isthmus or EEB at the inferolateral RA could block the CTI bidirectionally.
心外膜到心内膜的贯通（EEB）在心房性心律失常中广泛存在，是导致难以治疗的腔静脉峡部依赖的三尖瓣峡部（CTI）依赖性房扑（AFL）的原因。本研究旨在探讨 EEB 相关 CTI 依赖性 AFL 中 EEB 的电生理特征。
在三个机构中，使用超高密度、高分辨率标测系统对 142 例连续接受 CTI 依赖性 AFL 导管消融的患者中，确定了 6 例 EEB 相关 CTI 依赖性 AFL 患者。分析了激动图和消融过程。
在 6 例患者中发现了 7 个 EEB。在 3 例患者的心动过速期间记录到 4 个 EEB（包括右房间隔 3 个和间隔旁峡部 1 个）。在从冠状窦起搏时，在右下房的后外侧发现了另外 3 个 EEB。在 3 例患者中评估了通过 EEB 介导结构的传导特性。2 例患者仅表现为单向传导。激动图表明，在心房间隔有 EEB 的 CTI 依赖性 AFL 实际上是双心房大折返性房性心动过速（BiAT）。在 4 例中，在中心峡部进行密集消融可双向阻滞 CTI。但在 2 例中需要消融右下房的 EEB。同时，随着激活顺序的改变，在 EEB 部位的局部电位逐渐分裂成两个成分。
EEB 是难治性 CTI 依赖性 AFL 的一个潜在原因。EEB 介导的结构可能表现为单向传导。在心房间隔有 EEB 的 CTI 依赖性 AFL 可能代表 BiAT。密集消融中心峡部或右下房的 EEB 可双向阻滞 CTI。
